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The Project Gutenberg eBook of Fossil plants, Vol. 2
This eBook is for the use of anyone anywhere in the United States and most
other parts of the world at no cost and with almost no restrictions
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the Project Gutenberg License included with this eBook or online at
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this eBook.
Title: Fossil plants, Vol. 2
A text-book for students of botany and geology
Author: A. C. Seward
Release date: July 7, 2022 [eBook #68470]
Most recently updated: October 18, 2024
Language: English
Original publication: United Kingdom: Cambridge University Press, 1910
Other information and formats: www.gutenberg.org/ebooks/68470
Credits: Peter Becker, Robert Tonsing, Utrecht University and the Online
Distributed Proofreading Team at https://www.pgdp.net
*** START OF THE PROJECT GUTENBERG EBOOK FOSSIL
PLANTS, VOL. 2 ***
This eBook is for the use of anyone anywhere in the United States and most
other parts of the world at no cost and with almost no restrictions
whatsoever. You may copy it, give it away or re-use it under the terms of
the Project Gutenberg License included with this eBook or online at
www.gutenberg.org. If you are not located in the United States, you will
have to check the laws of the country where you are located before using
this eBook.
Title: Fossil plants, Vol. 2
A text-book for students of botany and geology
Author: A. C. Seward
Release date: July 7, 2022 [eBook #68470]
Most recently updated: October 18, 2024
Language: English
Original publication: United Kingdom: Cambridge University Press, 1910
Other information and formats: www.gutenberg.org/ebooks/68470
Credits: Peter Becker, Robert Tonsing, Utrecht University and the Online
Distributed Proofreading Team at https://www.pgdp.net
*** START OF THE PROJECT GUTENBERG EBOOK FOSSIL
PLANTS, VOL. 2 ***
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FOSSIL PLANTS.
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CAMBRIDGE UNIVERSITY PRESS
London: FETTER LANE, E.C.
C. F. CLAY, Manager
Edinburgh: 100, PRINCES STREET
London: H. K. LEWIS, 136, GOWER STREET, W.C.
Berlin: A. ASHER AND CO.
Leipzig: F. A. BROCKHAUS
New York: G. P. PUTNAM’S SONS
Bombay and Calcutta: MACMILLAN AND CO., Ltd.
All Rights reserved
London: FETTER LANE, E.C.
C. F. CLAY, Manager
Edinburgh: 100, PRINCES STREET
London: H. K. LEWIS, 136, GOWER STREET, W.C.
Berlin: A. ASHER AND CO.
Leipzig: F. A. BROCKHAUS
New York: G. P. PUTNAM’S SONS
Bombay and Calcutta: MACMILLAN AND CO., Ltd.
All Rights reserved
Page 7
Part of a transverse section of a Permian Osmundaceous Fern stem, Thamnopteris
Schlechtendalii (Eichwald). a, outer xylem; b, inner xylem. For description, see
page 329. (After Kidston and Gwynne-Vaughan. Very slightly reduced.)
Schlechtendalii (Eichwald). a, outer xylem; b, inner xylem. For description, see
page 329. (After Kidston and Gwynne-Vaughan. Very slightly reduced.)
Page 8
Page 9
F OS S IL P L A N T S
A TEXT-BOOK FOR STUDENTS
OF BOTANY AND GEOLOGY
BY
A. C. SEWARD, M.A., F.RS.
PROFESSOR OF BOTANY IN THE UNIVERSITY; FELLOW OF ST JOHN’S
COLLEGE AND HONORARY FELLOW OF EMMANUEL COLLEGE, CAMBRIDGE
WITH 265 ILLUSTRATIONS
VOL. II
CAMBRIDGE:
AT THE UNIVERSITY PRESS
1910
A TEXT-BOOK FOR STUDENTS
OF BOTANY AND GEOLOGY
BY
A. C. SEWARD, M.A., F.RS.
PROFESSOR OF BOTANY IN THE UNIVERSITY; FELLOW OF ST JOHN’S
COLLEGE AND HONORARY FELLOW OF EMMANUEL COLLEGE, CAMBRIDGE
WITH 265 ILLUSTRATIONS
VOL. II
CAMBRIDGE:
AT THE UNIVERSITY PRESS
1910
Page 10
Page 11
Cambridge:
PRINTED BY JOHN CLAY, M.A.
AT THE UNIVERSITY PRESS.
PRINTED BY JOHN CLAY, M.A.
AT THE UNIVERSITY PRESS.
Page 12
Page 13
PREFACE
I REGRET that pressure of other work has prevented the completion of this
Volume within a reasonable time since the publication of Volume I. Had
Volume II been written ten years ago, the discoveries made in the course of
the last decade would have given an out-of-date character to much of the
subject-matter. It is more especially in regard to the Ferns and the extinct
members of the Gymnosperms that our outlook has been materially altered
by recent contributions to Palaeobotany. It is, however, some satisfaction to
be able to add that recent progress has been relatively slight in that part of
the subject dealt with in the first volume.
The original intention was to complete the whole work in two volumes.
Soon after the second volume was begun, it became evident that the
remaining divisions of the plant-kingdom could not be included within the
compass of a single volume. I decided, therefore, to take the consequences
of having embarked on too ambitious a plan of treatment, and to preserve
uniformity of proportion by reserving the seed-bearing plants for a third
volume. The third volume will include the Pteridosperms, other than those
briefly described in the final chapter of the present volume, and other
classes of Gymnosperms. I propose also to devote such space as is available
within the limits of a text-book to the neglected subject of the geographical
distribution of plants at different stages in the history of the earth. It is my
intention to complete Volume III with as little delay as possible. As I have
written elsewhere, the past history of the Flowering plants needs special
treatment, and anything more than a mere compilation can be adequately
attempted only after considerable research and with the assistance of
botanists possessing a special knowledge of different families of
Angiosperms. The need of a critical examination of available data in regard
to the geological history of this dominant group will not be lost sight of.
I am well aware that while certain genera have received an undue share
of attention in the present volume, others have been ignored or treated with
scant consideration. For this inconsistency I have no excuse to offer, beyond
I REGRET that pressure of other work has prevented the completion of this
Volume within a reasonable time since the publication of Volume I. Had
Volume II been written ten years ago, the discoveries made in the course of
the last decade would have given an out-of-date character to much of the
subject-matter. It is more especially in regard to the Ferns and the extinct
members of the Gymnosperms that our outlook has been materially altered
by recent contributions to Palaeobotany. It is, however, some satisfaction to
be able to add that recent progress has been relatively slight in that part of
the subject dealt with in the first volume.
The original intention was to complete the whole work in two volumes.
Soon after the second volume was begun, it became evident that the
remaining divisions of the plant-kingdom could not be included within the
compass of a single volume. I decided, therefore, to take the consequences
of having embarked on too ambitious a plan of treatment, and to preserve
uniformity of proportion by reserving the seed-bearing plants for a third
volume. The third volume will include the Pteridosperms, other than those
briefly described in the final chapter of the present volume, and other
classes of Gymnosperms. I propose also to devote such space as is available
within the limits of a text-book to the neglected subject of the geographical
distribution of plants at different stages in the history of the earth. It is my
intention to complete Volume III with as little delay as possible. As I have
written elsewhere, the past history of the Flowering plants needs special
treatment, and anything more than a mere compilation can be adequately
attempted only after considerable research and with the assistance of
botanists possessing a special knowledge of different families of
Angiosperms. The need of a critical examination of available data in regard
to the geological history of this dominant group will not be lost sight of.
I am well aware that while certain genera have received an undue share
of attention in the present volume, others have been ignored or treated with
scant consideration. For this inconsistency I have no excuse to offer, beyond
Page 14
the statement that the subject is a large one, and selection is necessary even
though the work consists of three volumes.
The publication in 1909 of a collection of excellent photographs of
Palaeozoic Plants, with brief descriptive notes, by Mr Newell Arber, as one
of a series of popular “Nature Books,” bears striking testimony to the
remarkable spread of interest in the study of the vegetation of the past,
which is one of the outstanding features in the recent history of botanical
science.
In the list of illustrations I have mentioned the source of all figures which
have been previously published. I would, however, supplement the
statement of fact with an expression of thanks to corporate bodies and to
individuals who have allowed me to make use of blocks, drawings, or
photographs.
I wish to thank my colleague, Mr A. G. Tansley, for placing at my
disposal several blocks originally published in the pages of the New
Phytologist. To Professor Bertrand of Lille and to his son Dr Paul Bertrand I
am indebted for several prints and descriptive notes of specimens in their
possession. My friends Dr Nathorst of Stockholm and Dr Zeiller of Paris
have generously responded to my requests for information on various
points. I wish especially to thank Dr Kidston for several excellent prints of
specimens in his collection and for the loan of sections. I have profited by
more than one examination of his splendid collection at Stirling. Professor
Weiss has generously allowed me to borrow sections from the Manchester
University collections, more especially several which have been reproduced
in the chapter devoted to the genus Lepidodendron. To Professor F. W.
Oliver my thanks are due for the loan of sections from the collection under
his charge at University College. I have pleasure also in thanking Dr Scott,
not only for lending me sections of a Lepidodendron and for allowing me to
use some drawings of Miadesmia originally made by Mrs Scott for
reproduction in his invaluable book, Studies in Fossil Botany, but for kindly
undertaking the laborious task of reading the proofs of this volume. It
would be unfair to express my gratitude to Dr Scott for many helpful
suggestions and criticisms, without explicitly stating that thanks to a friend
for reading proofs must not be interpreted as an attempt to claim his support
for all statements or views expressed. The General Editor of the Series, Mr
A. E. Shipley, has also kindly read the proofs. I am under obligations also
though the work consists of three volumes.
The publication in 1909 of a collection of excellent photographs of
Palaeozoic Plants, with brief descriptive notes, by Mr Newell Arber, as one
of a series of popular “Nature Books,” bears striking testimony to the
remarkable spread of interest in the study of the vegetation of the past,
which is one of the outstanding features in the recent history of botanical
science.
In the list of illustrations I have mentioned the source of all figures which
have been previously published. I would, however, supplement the
statement of fact with an expression of thanks to corporate bodies and to
individuals who have allowed me to make use of blocks, drawings, or
photographs.
I wish to thank my colleague, Mr A. G. Tansley, for placing at my
disposal several blocks originally published in the pages of the New
Phytologist. To Professor Bertrand of Lille and to his son Dr Paul Bertrand I
am indebted for several prints and descriptive notes of specimens in their
possession. My friends Dr Nathorst of Stockholm and Dr Zeiller of Paris
have generously responded to my requests for information on various
points. I wish especially to thank Dr Kidston for several excellent prints of
specimens in his collection and for the loan of sections. I have profited by
more than one examination of his splendid collection at Stirling. Professor
Weiss has generously allowed me to borrow sections from the Manchester
University collections, more especially several which have been reproduced
in the chapter devoted to the genus Lepidodendron. To Professor F. W.
Oliver my thanks are due for the loan of sections from the collection under
his charge at University College. I have pleasure also in thanking Dr Scott,
not only for lending me sections of a Lepidodendron and for allowing me to
use some drawings of Miadesmia originally made by Mrs Scott for
reproduction in his invaluable book, Studies in Fossil Botany, but for kindly
undertaking the laborious task of reading the proofs of this volume. It
would be unfair to express my gratitude to Dr Scott for many helpful
suggestions and criticisms, without explicitly stating that thanks to a friend
for reading proofs must not be interpreted as an attempt to claim his support
for all statements or views expressed. The General Editor of the Series, Mr
A. E. Shipley, has also kindly read the proofs. I am under obligations also
Page 15
for assistance of various kinds to Prof. Thomas of Auckland, New Zealand,
to Mr Boodle of Kew, to Mr D. M. S. Watson of Manchester, to Mr T. G.
Hill of University College, and to Mr Gordon of Emmanuel College,
Cambridge. I am indebted to the kind offices of Miss M. C. Knowles for the
photograph of the specimen of Archaeopteris hibernica in the Irish National
Museum, Dublin, reproduced on page 561.
Many of the illustrations are reproduced from drawings by my wife:
those made from the actual specimens are distinguished by the addition of
the initials M. S. I am grateful to her also for some improvements in the
letter-press. For the drawings made from sections and for some of the
outline sketches I am responsible. I have availed myself freely of the
facilities afforded by Professor McKenny Hughes in the Sedgwick Museum
of Geology for the examination of specimens under the charge of Mr
Newell Arber, the University Demonstrator in Palaeobotany. It is a pleasure
to add that, as on former occasions, I am indebted to the vigilance of the
Readers of the University Press for the detection of several errors which
escaped my notice in the revision of the proofs.
A. C. SEWARD.
Botany School, Cambridge.
March 12, 1910.
to Mr Boodle of Kew, to Mr D. M. S. Watson of Manchester, to Mr T. G.
Hill of University College, and to Mr Gordon of Emmanuel College,
Cambridge. I am indebted to the kind offices of Miss M. C. Knowles for the
photograph of the specimen of Archaeopteris hibernica in the Irish National
Museum, Dublin, reproduced on page 561.
Many of the illustrations are reproduced from drawings by my wife:
those made from the actual specimens are distinguished by the addition of
the initials M. S. I am grateful to her also for some improvements in the
letter-press. For the drawings made from sections and for some of the
outline sketches I am responsible. I have availed myself freely of the
facilities afforded by Professor McKenny Hughes in the Sedgwick Museum
of Geology for the examination of specimens under the charge of Mr
Newell Arber, the University Demonstrator in Palaeobotany. It is a pleasure
to add that, as on former occasions, I am indebted to the vigilance of the
Readers of the University Press for the detection of several errors which
escaped my notice in the revision of the proofs.
A. C. SEWARD.
Botany School, Cambridge.
March 12, 1910.
Page 16
Page 17
TABLE OF CONTENTS
———————
CHAPTER XII
SPHENOPHYLLALES (continued from Volume i.). Pp. 1–16.
PAGE
Sphenophyllum 1–7
Cheirostrobus 7–12
Sphenophyllales and Psilotaceae 12–16
CHAPTER XIII
PSILOTALES. Pp. 17–29.
Psilotum and Tmesipteris 17–24
Fossils described by authors as being closely allied to Psilotum 24–26
Psilophyton 26–29
CHAPTER XIV
LYCOPODIALES. Pp. 30–91.
Recent Lycopodiales (General) 30–33
Lycopodiaceae (Recent) 33–49
Selaginellaceae (Recent) 49–58
Isoetaceae (Recent) 58–66
Fossil Lycopodiales 66–91
Isoetaceae (Fossil) 66–68
Pleuromeia 68–73
Herbaceous fossil species of Lycopodiales 73–91
Lycopodites 76–84
Selaginellites 85–88
Lycostrobus 88–91
Poecilitostachys 91
———————
CHAPTER XII
SPHENOPHYLLALES (continued from Volume i.). Pp. 1–16.
PAGE
Sphenophyllum 1–7
Cheirostrobus 7–12
Sphenophyllales and Psilotaceae 12–16
CHAPTER XIII
PSILOTALES. Pp. 17–29.
Psilotum and Tmesipteris 17–24
Fossils described by authors as being closely allied to Psilotum 24–26
Psilophyton 26–29
CHAPTER XIV
LYCOPODIALES. Pp. 30–91.
Recent Lycopodiales (General) 30–33
Lycopodiaceae (Recent) 33–49
Selaginellaceae (Recent) 49–58
Isoetaceae (Recent) 58–66
Fossil Lycopodiales 66–91
Isoetaceae (Fossil) 66–68
Pleuromeia 68–73
Herbaceous fossil species of Lycopodiales 73–91
Lycopodites 76–84
Selaginellites 85–88
Lycostrobus 88–91
Poecilitostachys 91
Page 18
CHAPTER XV
ARBORESCENT LYCOPODIALES. Pp. 92–195.
Lepidodendron 93–181
i. General 93–97
ii. Leaves and Leaf-cushions 97–105
iii. Lepidophloios 105–109
iv. The anatomy of Lepidodendron vasculare 109–123
v. Lepidodendron stems as represented by casts and impressions of partially
decorticated specimens 123–128
a. Knorria 124–126; b. Bergeria 126, 127; c. Aspidiaria 127, 128.
vi. Lepidodendroid axes known as Ulodendron and Halonia 128–139
a. Ulodendron 128–135; b. Halonia 135–139.
vii. Anatomical characters of vegetative Lepidodendron shoots 139–181
1. Lepidodendron esnostense 139, 140; 2. L. rhodumnense 140; 3. L.
saalfeldense 141; 4. L. fuliginosum 141–160; 5. L. Harcourtii 160–163; 6.
L. Wünschianum 163–171; 7. L. macrophyllum 171; 8. L. Veltheimianum
171–177; 9. L. Pedroanum 177, 178; 10. L. australe 178–181.
viii. Fertile shoots of Lepidodendreae 181–195
A. Lepidostrobus 181–191. i. Lepidostrobus variabilis 187, 188; ii. L.
oldhamius 188–190; iii. L. Brownii, etc. 190, 191.
B. Spencerites 192–195.
CHAPTER XVI
SIGILLARIA. Pp. 196–226.
i. General 196–210; ii. Leaves 210–215; iii. Fertile shoots 215–218; iv. The structure
of Sigillarian stems 218–224; v. Sigillaria Brardi 224–226.
CHAPTER XVII
STIGMARIA. Pp. 227–247.
CHAPTER XVIII
BOTHRODENDREAE. Pp. 248–270.
Bothrodendron 248–264. a. B. minutifolium 251–253; b. B. punctatum 254, 255; c. B.
kiltorkense 255–259. Anatomy of vegetative shoots of Bothrodendron 260–262;
Cones of Bothrodendron 262–264.
ARBORESCENT LYCOPODIALES. Pp. 92–195.
Lepidodendron 93–181
i. General 93–97
ii. Leaves and Leaf-cushions 97–105
iii. Lepidophloios 105–109
iv. The anatomy of Lepidodendron vasculare 109–123
v. Lepidodendron stems as represented by casts and impressions of partially
decorticated specimens 123–128
a. Knorria 124–126; b. Bergeria 126, 127; c. Aspidiaria 127, 128.
vi. Lepidodendroid axes known as Ulodendron and Halonia 128–139
a. Ulodendron 128–135; b. Halonia 135–139.
vii. Anatomical characters of vegetative Lepidodendron shoots 139–181
1. Lepidodendron esnostense 139, 140; 2. L. rhodumnense 140; 3. L.
saalfeldense 141; 4. L. fuliginosum 141–160; 5. L. Harcourtii 160–163; 6.
L. Wünschianum 163–171; 7. L. macrophyllum 171; 8. L. Veltheimianum
171–177; 9. L. Pedroanum 177, 178; 10. L. australe 178–181.
viii. Fertile shoots of Lepidodendreae 181–195
A. Lepidostrobus 181–191. i. Lepidostrobus variabilis 187, 188; ii. L.
oldhamius 188–190; iii. L. Brownii, etc. 190, 191.
B. Spencerites 192–195.
CHAPTER XVI
SIGILLARIA. Pp. 196–226.
i. General 196–210; ii. Leaves 210–215; iii. Fertile shoots 215–218; iv. The structure
of Sigillarian stems 218–224; v. Sigillaria Brardi 224–226.
CHAPTER XVII
STIGMARIA. Pp. 227–247.
CHAPTER XVIII
BOTHRODENDREAE. Pp. 248–270.
Bothrodendron 248–264. a. B. minutifolium 251–253; b. B. punctatum 254, 255; c. B.
kiltorkense 255–259. Anatomy of vegetative shoots of Bothrodendron 260–262;
Cones of Bothrodendron 262–264.
Page 19
Pinakodendron 264
Omphalophloios 264–266
General considerations 266–270
CHAPTER XIX
SEED-BEARING PLANTS CLOSELY ALLIED TO
MEMBERS OF THE LYCOPODIALES. Pp. 271–279.
i. Lepidocarpon 271–275; ii. Miadesmia 275–279.
CHAPTER XX
FILICALES. Pp. 280–323.
I. Leptosporangiate Filicales 283–316
Eufilicineae 284–316. Osmundaceae 285, 286; Schizaeaceae 286–291;
Matonineae 291–293; Loxsomaceae 293; Hymenophyllaceae 294;
Cyatheaceae 294–296; Dennstaedtiinae 296; Polypodiaceae 296;
Parkeriaceae 297; Dipteridinae 298.
The habit, leaf-form, and distribution of ferns 300–309; The anatomy of
ferns 309–316.
II. Marattiales 316–321
III. Ophioglossales 321–323
CHAPTER XXI
FOSSIL FERNS. Pp. 324–394.
Osmundaceae 324–346; Schizaeaceae 346–351; Gleicheniaceae 351–355; Matonineae 355–363;
Hymenophyllaceae 363–365; Cyatheaceae 365–375; Polypodiaceae 375–380; Dipteridinae
380–394.
CHAPTER XXII
MARATTIALES (FOSSIL). Pp. 395–411.
Ptychocarpus 397; Danaeites 398; Parapecopteris 398; Asterotheca 398–400; Hawlea 400;
Scolecopteris 401, 402; Discopteris 402–404; Dactylotheca 404–406; Renaultia 406; Zeilleria
407; Urnatopteris 407; Marattiopsis 407–409; Danaeopsis 409; Nathorstia 410, 411.
CHAPTER XXIII
Omphalophloios 264–266
General considerations 266–270
CHAPTER XIX
SEED-BEARING PLANTS CLOSELY ALLIED TO
MEMBERS OF THE LYCOPODIALES. Pp. 271–279.
i. Lepidocarpon 271–275; ii. Miadesmia 275–279.
CHAPTER XX
FILICALES. Pp. 280–323.
I. Leptosporangiate Filicales 283–316
Eufilicineae 284–316. Osmundaceae 285, 286; Schizaeaceae 286–291;
Matonineae 291–293; Loxsomaceae 293; Hymenophyllaceae 294;
Cyatheaceae 294–296; Dennstaedtiinae 296; Polypodiaceae 296;
Parkeriaceae 297; Dipteridinae 298.
The habit, leaf-form, and distribution of ferns 300–309; The anatomy of
ferns 309–316.
II. Marattiales 316–321
III. Ophioglossales 321–323
CHAPTER XXI
FOSSIL FERNS. Pp. 324–394.
Osmundaceae 324–346; Schizaeaceae 346–351; Gleicheniaceae 351–355; Matonineae 355–363;
Hymenophyllaceae 363–365; Cyatheaceae 365–375; Polypodiaceae 375–380; Dipteridinae
380–394.
CHAPTER XXII
MARATTIALES (FOSSIL). Pp. 395–411.
Ptychocarpus 397; Danaeites 398; Parapecopteris 398; Asterotheca 398–400; Hawlea 400;
Scolecopteris 401, 402; Discopteris 402–404; Dactylotheca 404–406; Renaultia 406; Zeilleria
407; Urnatopteris 407; Marattiopsis 407–409; Danaeopsis 409; Nathorstia 410, 411.
CHAPTER XXIII
Page 20
PSARONIEAE. Pp. 412–426.
CHAPTER XXIV
OPHIOGLOSSALES (FOSSIL). Pp. 427–431.
CHAPTER XXV
COENOPTERIDEAE. Pp. 432–472.
I. Botryoptereae 434–443
II. Zygoptereae 443–470
CHAPTER XXVI
HYDROPTERIDEAE AND SAGENOPTERIS. Pp. 473–483.
Marsiliaceae 473–475; Salviniaceae 475–477; Sagenopteris 477–483.
CHAPTER XXVII
GENERA OF PTERIDOSPERMS, FERNS, AND PLANTAE INCERTAE SEDIS. Pp. 484–580.
Taeniopteris 485–494; Weichselia 494–496; Glossopteris 496–512; Gangamopteris 512–517;
Lesleya 517–519; Neuropteridium 519–523; Cardiopteris 523–525; Aphlebia 525–529;
Sphenopteris 529–532; Mariopteris, Diplotmema, Palmatopteris 532–537; Cephalotheca 537;
Thinnfeldia 537–544; Lomatopteris 544–546; Cycadopteris 546; Ptilozamites 546–548;
Ctenopteris 548–550; Dichopteris 550–552; Odontopteris 552–556; Callipteris 557–559;
Callipteridium 560; Archaeopteris 552–565; Neuropteris 565–571; Cyclopteris 571, 572;
Linopteris 572, 573; Alethopteris 573–576; Lonchopteris 576; Pecopteris 576–580.
Pp. 609–
INDEX 624
CHAPTER XXIV
OPHIOGLOSSALES (FOSSIL). Pp. 427–431.
CHAPTER XXV
COENOPTERIDEAE. Pp. 432–472.
I. Botryoptereae 434–443
II. Zygoptereae 443–470
CHAPTER XXVI
HYDROPTERIDEAE AND SAGENOPTERIS. Pp. 473–483.
Marsiliaceae 473–475; Salviniaceae 475–477; Sagenopteris 477–483.
CHAPTER XXVII
GENERA OF PTERIDOSPERMS, FERNS, AND PLANTAE INCERTAE SEDIS. Pp. 484–580.
Taeniopteris 485–494; Weichselia 494–496; Glossopteris 496–512; Gangamopteris 512–517;
Lesleya 517–519; Neuropteridium 519–523; Cardiopteris 523–525; Aphlebia 525–529;
Sphenopteris 529–532; Mariopteris, Diplotmema, Palmatopteris 532–537; Cephalotheca 537;
Thinnfeldia 537–544; Lomatopteris 544–546; Cycadopteris 546; Ptilozamites 546–548;
Ctenopteris 548–550; Dichopteris 550–552; Odontopteris 552–556; Callipteris 557–559;
Callipteridium 560; Archaeopteris 552–565; Neuropteris 565–571; Cyclopteris 571, 572;
Linopteris 572, 573; Alethopteris 573–576; Lonchopteris 576; Pecopteris 576–580.
Pp. 609–
INDEX 624
Page 21
Page 22
LIST OF ILLUSTRATIONS
Several of the illustrations are printed from blocks for which I am indebted to learned societies or to
individuals. The sources from which clichés were obtained are mentioned within square brackets.
Frontispiece. Thamnopteris Schlechtendalii (Eich.). From a photograph given to me by Dr Kidston
and Mr Gwynne-Vaughan. (page 329.)
Fig. Page
112. Sphenophyllostachys 2
113. Sphenophyllostachys Römeri 3
Sphenophyllum trichomatosum
S. majus
114, 115. Sphenophyllostachys fertilis 4, 5
[Council of the Royal Society of London.]
116. Sphenophyllostachys Dawsoni 6
[Mr A. G. Tansley, Editor of the New Phytologist.]
117. Cheirostrobus pettycurensis 8
Pseudobornia ursina
118. Psilotum triquetrum 18
119. Psilotum triquetrum (anatomy) 20
120. Tmesipteris tannensis 22
121. Lycopodium (seven species) 35
122. Lycopodium squarrosum 36
123. Lycopodium cernuum 37
124. Lycopodium obscurum 38
125. Lycopodium (anatomy of stem) 41
126. Lycopodium (anatomy of cones) 45
127–129. Lycopodium cernuum (cone) 47–49
[Council of the Royal Society of Edinburgh.]
130. Selaginella grandis 50
131. Selaginella (anatomy) 52
132. Isoetes echinospora 59
I. lacustris
133. Isoetes lacustris (anatomy) 62
134. Pleuromeia Sternbergi 70
135. Selaginellites and Lycopodites 80
136. Lycopodites lanceolatus 81
[Council of the Geological Society of London.]
Several of the illustrations are printed from blocks for which I am indebted to learned societies or to
individuals. The sources from which clichés were obtained are mentioned within square brackets.
Frontispiece. Thamnopteris Schlechtendalii (Eich.). From a photograph given to me by Dr Kidston
and Mr Gwynne-Vaughan. (page 329.)
Fig. Page
112. Sphenophyllostachys 2
113. Sphenophyllostachys Römeri 3
Sphenophyllum trichomatosum
S. majus
114, 115. Sphenophyllostachys fertilis 4, 5
[Council of the Royal Society of London.]
116. Sphenophyllostachys Dawsoni 6
[Mr A. G. Tansley, Editor of the New Phytologist.]
117. Cheirostrobus pettycurensis 8
Pseudobornia ursina
118. Psilotum triquetrum 18
119. Psilotum triquetrum (anatomy) 20
120. Tmesipteris tannensis 22
121. Lycopodium (seven species) 35
122. Lycopodium squarrosum 36
123. Lycopodium cernuum 37
124. Lycopodium obscurum 38
125. Lycopodium (anatomy of stem) 41
126. Lycopodium (anatomy of cones) 45
127–129. Lycopodium cernuum (cone) 47–49
[Council of the Royal Society of Edinburgh.]
130. Selaginella grandis 50
131. Selaginella (anatomy) 52
132. Isoetes echinospora 59
I. lacustris
133. Isoetes lacustris (anatomy) 62
134. Pleuromeia Sternbergi 70
135. Selaginellites and Lycopodites 80
136. Lycopodites lanceolatus 81
[Council of the Geological Society of London.]
Page 23
Fig. Page
137. Lycopodites falcatus 83
138. Selaginellites primaevus 86
139. Lycostrobus Scotti 89
140. Picea excelsa 94
141. Lepidodendron Sternbergii 97
142. Sigillaria (leaves) 98
143. Lepidodendron (leaves) 99
144. Lepidodendron Veltheimianum 101
145. Lepidodendron leaf-cushion 102
146. Lepidodendron and Lepidophloios leaf-cushions 104
147. Lepidophloios leaf-cushion 108
148–155. Lepidodendron vasculare 112–122
156. Knorria mirabilis 125
157. Lepidodendron Veltheimianum (Ulodendron) 129
158. Diagrammatic section illustrating the branch-theory of the 132
Ulodendroid scar
[Council of the Manchester Literary and Philosophical Society.]
159. Pinus clausa 134
160. Lepidophloios scoticus 135
161. Halonia tortuosa 136
162–167. Lepidodendron fuliginosum 143–147
[Council of the Cambridge Philosophical Society.]
168. Lepidodendron vasculare and L. fuliginosum 148
169. Lepidodendron fuliginosum 149
170–172. L. fuliginosum 150–152
173. Lepidodendron obovatum 154
174–176. Lepidodendron aculeatum 155, 156
[Oxford University Press: Annals of Botany.]
177. Stigmaria radiculosa 157
178. Stigmarian rootlet 158
179. Lepidodendron Harcourtii and L. fuliginosum 162
180. Lepidodendron Wünschianum 163
181, 182. L. Wünschianum 165, 166
183, 184. L. Wünschianum 168, 169
[Editor of the New Phytologist.]
185. Lepidodendron Veltheimianum 173
186. L. Veltheimianum and L. macrophyllum 176
187. Lepidodendron australe 179
[Dr H. Woodward, Editor of the Geological Magazine.]
188, 189. Lepidostrobus 183, 184
190. Lepidodendron and Lepidostrobi 186
137. Lycopodites falcatus 83
138. Selaginellites primaevus 86
139. Lycostrobus Scotti 89
140. Picea excelsa 94
141. Lepidodendron Sternbergii 97
142. Sigillaria (leaves) 98
143. Lepidodendron (leaves) 99
144. Lepidodendron Veltheimianum 101
145. Lepidodendron leaf-cushion 102
146. Lepidodendron and Lepidophloios leaf-cushions 104
147. Lepidophloios leaf-cushion 108
148–155. Lepidodendron vasculare 112–122
156. Knorria mirabilis 125
157. Lepidodendron Veltheimianum (Ulodendron) 129
158. Diagrammatic section illustrating the branch-theory of the 132
Ulodendroid scar
[Council of the Manchester Literary and Philosophical Society.]
159. Pinus clausa 134
160. Lepidophloios scoticus 135
161. Halonia tortuosa 136
162–167. Lepidodendron fuliginosum 143–147
[Council of the Cambridge Philosophical Society.]
168. Lepidodendron vasculare and L. fuliginosum 148
169. Lepidodendron fuliginosum 149
170–172. L. fuliginosum 150–152
173. Lepidodendron obovatum 154
174–176. Lepidodendron aculeatum 155, 156
[Oxford University Press: Annals of Botany.]
177. Stigmaria radiculosa 157
178. Stigmarian rootlet 158
179. Lepidodendron Harcourtii and L. fuliginosum 162
180. Lepidodendron Wünschianum 163
181, 182. L. Wünschianum 165, 166
183, 184. L. Wünschianum 168, 169
[Editor of the New Phytologist.]
185. Lepidodendron Veltheimianum 173
186. L. Veltheimianum and L. macrophyllum 176
187. Lepidodendron australe 179
[Dr H. Woodward, Editor of the Geological Magazine.]
188, 189. Lepidostrobus 183, 184
190. Lepidodendron and Lepidostrobi 186
Page 24
Fig. Page
191. Lepidostrobus 188
192. Spencerites insignis 193
[Oxford University Press: Annals of Botany.]
193. Sigillaria elegans, S. rugosa, S. tessellata, Omphalophloios anglicus 197
194. Sigillaria McMurtriei 199
195. Sigillaria mammillaris 199
196. Sigillaria Brardi, S. laevigata, and Lepidodendron Wortheni 200
197. Carica sp. 202
198, 199. Sigillaria 205, 206
200. Sigillaria Brardi 212
201. Sigillariostrobus 216
202. Sigillaria elegans and S. elongata 220
203. Sigillaria Brardi 225
204, 205. Stigmaria ficoides 227, 228
206. Cyperus papyrus 230
207, 208. Stages in the development of Sigillaria 236
209. Stigmariopsis 237
210. Stigmaria 241
211. Bothrodendron punctatum 250
212. Bothrodendron minutifolium, B. punctatum, B. kiltorkense and 252
Lepidostrobus Olryi
213. Bothrodendron minutifolium 254
214. Bothrodendron Leslei 258
[Trustees of the British Museum.]
215. Bothrodendron mundum 259
216. Bothrostrobus 263
[Council of the Manchester Literary and Philosophical Society.]
217. Omphalophloios 265
218. Lepidocarpon Lomaxi 273
219. Miadesmia and Bothrodendron 276
220. Angiopteris evecta and Cycas revoluta 283
221. Osmunda cinnamomea, O. regalis, and Todea barbara 286
222. Schizaea elegans 287
223. Aneimia rotundifolia 288
224. Aneimia flexuosa, A. phyllitidis, Hymenophyllum, Matonia 289
pectinata, Thyrsopteris elegans, Gleichenia
225. Gleichenia dicarpa 290
226. Gleichenites Rostafinskii, Gleichenia dicarpa, G. dichotoma 290
227. Matonia pectinata 292
[Council of the Royal Society.]
228. Matonia pectinata 293
191. Lepidostrobus 188
192. Spencerites insignis 193
[Oxford University Press: Annals of Botany.]
193. Sigillaria elegans, S. rugosa, S. tessellata, Omphalophloios anglicus 197
194. Sigillaria McMurtriei 199
195. Sigillaria mammillaris 199
196. Sigillaria Brardi, S. laevigata, and Lepidodendron Wortheni 200
197. Carica sp. 202
198, 199. Sigillaria 205, 206
200. Sigillaria Brardi 212
201. Sigillariostrobus 216
202. Sigillaria elegans and S. elongata 220
203. Sigillaria Brardi 225
204, 205. Stigmaria ficoides 227, 228
206. Cyperus papyrus 230
207, 208. Stages in the development of Sigillaria 236
209. Stigmariopsis 237
210. Stigmaria 241
211. Bothrodendron punctatum 250
212. Bothrodendron minutifolium, B. punctatum, B. kiltorkense and 252
Lepidostrobus Olryi
213. Bothrodendron minutifolium 254
214. Bothrodendron Leslei 258
[Trustees of the British Museum.]
215. Bothrodendron mundum 259
216. Bothrostrobus 263
[Council of the Manchester Literary and Philosophical Society.]
217. Omphalophloios 265
218. Lepidocarpon Lomaxi 273
219. Miadesmia and Bothrodendron 276
220. Angiopteris evecta and Cycas revoluta 283
221. Osmunda cinnamomea, O. regalis, and Todea barbara 286
222. Schizaea elegans 287
223. Aneimia rotundifolia 288
224. Aneimia flexuosa, A. phyllitidis, Hymenophyllum, Matonia 289
pectinata, Thyrsopteris elegans, Gleichenia
225. Gleichenia dicarpa 290
226. Gleichenites Rostafinskii, Gleichenia dicarpa, G. dichotoma 290
227. Matonia pectinata 292
[Council of the Royal Society.]
228. Matonia pectinata 293
Page 25
Fig. Page
229. Thyrsopteris elegans, Cyathea spinulosa, Dicksonia coniifolia, D. 294
culcita, Davallia concinna, Alsophila excelsa
230. Dicksonia Bertervana 295
[Trustees of the British Museum.]
231. Dipteris quinquefurcata, D. conjugata, D. Wallichii, and 297
Polypodium quercifolium
232. Davallia aculeata 299
233. Polypodium Billardieri 302
234. Polypodium quercifolium 303
235. Hemitelia capensis 304
236 a, 236 b. Pteris aquilina 305, 306
[Council of the Linnean Society of London.]
237. Matonia pectinata, Matonidium, Gleichenia dicarpa, and 310
Trichomanes reniforme (anatomy)
238. Trichomanes scandens 311
[Editor of the New Phytologist.]
239. Platyzoma microphylla 312
[Editor of the New Phytologist.]
240. Cyathea Imrayana 313
[Editor of the New Phytologist.].
241. Angiopteris evecta and Marattia fraxinea 317
242. Angiopteris evecta and Danaea 318
243, 244. Angiopteris evecta 319
245. Marattia fraxinea, M. Kaulfussii, Kaulfussia, and Marattiopsis 320
Münsteri
246. Ophioglossum vulgatum 322
247. Botrychium virginianum 322
248. Zalesskya gracilis 327
249. Zalesskya diploxylon 328
250. Thamnopteris Schlechtendalii 330
251. Lonchopteris virginiensis 331
252. Osmundites Dunlopi 333
253, 254. Osmundites Kolbei 334, 335
[Editor of the Geological Magazine.]
255. O. Kolbei 336
256. Cladophlebis denticulata, Todites Williamsoni, Discopteris Rallii, 340
Kidstonia heracleensis, and Todeopsis primaeva
257, 258. Cladophlebis denticulata 342, 345
259. Klukia exilis 348
[Council of the Cambridge Philosophical Society.]
260. Ruffordia Goepperti 349
261. Chrysodium lanzaeanum, Lygodium Kaulfussi, Marattia Hookeri 350
229. Thyrsopteris elegans, Cyathea spinulosa, Dicksonia coniifolia, D. 294
culcita, Davallia concinna, Alsophila excelsa
230. Dicksonia Bertervana 295
[Trustees of the British Museum.]
231. Dipteris quinquefurcata, D. conjugata, D. Wallichii, and 297
Polypodium quercifolium
232. Davallia aculeata 299
233. Polypodium Billardieri 302
234. Polypodium quercifolium 303
235. Hemitelia capensis 304
236 a, 236 b. Pteris aquilina 305, 306
[Council of the Linnean Society of London.]
237. Matonia pectinata, Matonidium, Gleichenia dicarpa, and 310
Trichomanes reniforme (anatomy)
238. Trichomanes scandens 311
[Editor of the New Phytologist.]
239. Platyzoma microphylla 312
[Editor of the New Phytologist.]
240. Cyathea Imrayana 313
[Editor of the New Phytologist.].
241. Angiopteris evecta and Marattia fraxinea 317
242. Angiopteris evecta and Danaea 318
243, 244. Angiopteris evecta 319
245. Marattia fraxinea, M. Kaulfussii, Kaulfussia, and Marattiopsis 320
Münsteri
246. Ophioglossum vulgatum 322
247. Botrychium virginianum 322
248. Zalesskya gracilis 327
249. Zalesskya diploxylon 328
250. Thamnopteris Schlechtendalii 330
251. Lonchopteris virginiensis 331
252. Osmundites Dunlopi 333
253, 254. Osmundites Kolbei 334, 335
[Editor of the Geological Magazine.]
255. O. Kolbei 336
256. Cladophlebis denticulata, Todites Williamsoni, Discopteris Rallii, 340
Kidstonia heracleensis, and Todeopsis primaeva
257, 258. Cladophlebis denticulata 342, 345
259. Klukia exilis 348
[Council of the Cambridge Philosophical Society.]
260. Ruffordia Goepperti 349
261. Chrysodium lanzaeanum, Lygodium Kaulfussi, Marattia Hookeri 350
Page 26
Fig. Page
262. Gleichenites longipennis, G. delicatula, G. Nordenskioldi and G. 354
Zippei
263. Gleichenites hantonensis 356
[Council of the Palaeontographical Society.]
264. Laccopteris elegans 357
[Council of the Royal Society.]
265. Matonidium Wiesneri, Marattiopsis marantacea, Gleichenites 358
gracilis, Laccopteris Goepperti, and L. Muensteri
266. Laccopteris polypodioides 359
[Trustees of the British Museum.]
267. Laccopteris 359
[Trustees of the British Museum.]
268. ? Laccopteris polypodioides 360
[Trustees of the British Museum.]
269. Matonidium Goepperti 362
[Editor of the Encyclopaedia Britannica.]
270. Senftenbergia elegans, Oligocarpia Brongniartii, Trichomanes sp., 364
Hymenophyllum tunbridgense, Sphenopteris (Hymenophyllites)
quadridactylites
271. Coniopteris hymenophylloides 368
[Council of the Manchester Literary and Philosophical Society.]
272. C. hymenophylloides 369
273. Coniopteris quinqueloba 370
274. Coniopteris arguta 371
275. Coniopteris arguta and C. hymenophylloides 372
276. Oncopteris Nettvalli 373
277. Protopteris punctata 373
278. Laccopteris polypodioides, L. Muensteri, Dicksonia, Onychiopsis 374
Mantelli, Hausmannia Sewardi, H. Kohlmanni, and Protopteris
Witteana
279. Adiantides antiquus and A. lindsayoides 376
280. Onychiopsis Mantelli 379
281. Dictyophyllum exile 381
282. Dictyophyllum Nilssoni, Rhizomopteris Schenki, Camptopteris 382
spiralis, and D. exile
283. Dictyophyllum rugosum 384
[Trustees of the British Museum.]
284. Thaumatopteris Münsteri 386
285. Clathropteris meniscoides 387
286. Clathropteris egyptiaca 388
[Editor of the Geological Magazine.]
287. Camptopteris spiralis 389
262. Gleichenites longipennis, G. delicatula, G. Nordenskioldi and G. 354
Zippei
263. Gleichenites hantonensis 356
[Council of the Palaeontographical Society.]
264. Laccopteris elegans 357
[Council of the Royal Society.]
265. Matonidium Wiesneri, Marattiopsis marantacea, Gleichenites 358
gracilis, Laccopteris Goepperti, and L. Muensteri
266. Laccopteris polypodioides 359
[Trustees of the British Museum.]
267. Laccopteris 359
[Trustees of the British Museum.]
268. ? Laccopteris polypodioides 360
[Trustees of the British Museum.]
269. Matonidium Goepperti 362
[Editor of the Encyclopaedia Britannica.]
270. Senftenbergia elegans, Oligocarpia Brongniartii, Trichomanes sp., 364
Hymenophyllum tunbridgense, Sphenopteris (Hymenophyllites)
quadridactylites
271. Coniopteris hymenophylloides 368
[Council of the Manchester Literary and Philosophical Society.]
272. C. hymenophylloides 369
273. Coniopteris quinqueloba 370
274. Coniopteris arguta 371
275. Coniopteris arguta and C. hymenophylloides 372
276. Oncopteris Nettvalli 373
277. Protopteris punctata 373
278. Laccopteris polypodioides, L. Muensteri, Dicksonia, Onychiopsis 374
Mantelli, Hausmannia Sewardi, H. Kohlmanni, and Protopteris
Witteana
279. Adiantides antiquus and A. lindsayoides 376
280. Onychiopsis Mantelli 379
281. Dictyophyllum exile 381
282. Dictyophyllum Nilssoni, Rhizomopteris Schenki, Camptopteris 382
spiralis, and D. exile
283. Dictyophyllum rugosum 384
[Trustees of the British Museum.]
284. Thaumatopteris Münsteri 386
285. Clathropteris meniscoides 387
286. Clathropteris egyptiaca 388
[Editor of the Geological Magazine.]
287. Camptopteris spiralis 389
Page 27
Fig. Page
288. Hausmannia dichotoma 391
289. Hausmannia sp. 393
290. Alethopteris lonchitica, Lonchopteris rugosa, Sphenopteris 399
Hoeninghausi, Parapecopteris neuropteroides,and Pecopteris
(Dactylotheca) plumosa
291. Ptychocarpus unita, Asterotheca Sternbergii, Danaeites 400
sarepontanus, Hawlea Miltoni, H. pulcherrima, Scolecopteris
elegans
292. Dactylotheca plumosa 405
293. D. plumosa 406
294. Nathorstia angustifolia and N. latifolia 410
295. Psaronius 414
296. Psaronius infarctus, P. coalescens, P. musaeformis, and P. 416
asterolithus
297. Pecopteris Sterzeli 419
298. Caulopteris peltigera and Megaphyton insigne 421
299. Ptychopteris 423
300. Dicksonia antarctica 424
301. Rhacopteris sp. 427
302. Noeggerathia foliosa 429
303. Chiropteris Zeilleri 430
[Annals of the South African Museum.]
304. Tubicaulis solenites 435
[Editor of the New Phytologist.]
305. Botryopteris cylindrica 439
306. Botryopteris ramosa 441
307. Botryopteris antiqua 442
308. Clepsydropsis antiqua, Etapteris Scotti, Diplolabis forensis, 444
Zygopteris primaria, Stauropteris oldhamia
309. Diplolabis forensis, Botryopteris forensis, Corynepteris coralloides, 445
Schizopteris pinnata
310. Metaclepsydropsis duplex, Stauropteris oldhamia, Ankyropteris 450
scandens
311. Ankyropteris Grayi 451
312. Thamnopteris Schlechtendalii, Ankyropteris corrugata, A. 453
bibractensis
313. Ankyropteris bibractensis 454
314. Ankyropteris corrugata 457
315. Ankyropteris corrugata 458
[Editor of the New Phytologist.]
316, 317. Ankyropteris corrugata 459, 460
288. Hausmannia dichotoma 391
289. Hausmannia sp. 393
290. Alethopteris lonchitica, Lonchopteris rugosa, Sphenopteris 399
Hoeninghausi, Parapecopteris neuropteroides,and Pecopteris
(Dactylotheca) plumosa
291. Ptychocarpus unita, Asterotheca Sternbergii, Danaeites 400
sarepontanus, Hawlea Miltoni, H. pulcherrima, Scolecopteris
elegans
292. Dactylotheca plumosa 405
293. D. plumosa 406
294. Nathorstia angustifolia and N. latifolia 410
295. Psaronius 414
296. Psaronius infarctus, P. coalescens, P. musaeformis, and P. 416
asterolithus
297. Pecopteris Sterzeli 419
298. Caulopteris peltigera and Megaphyton insigne 421
299. Ptychopteris 423
300. Dicksonia antarctica 424
301. Rhacopteris sp. 427
302. Noeggerathia foliosa 429
303. Chiropteris Zeilleri 430
[Annals of the South African Museum.]
304. Tubicaulis solenites 435
[Editor of the New Phytologist.]
305. Botryopteris cylindrica 439
306. Botryopteris ramosa 441
307. Botryopteris antiqua 442
308. Clepsydropsis antiqua, Etapteris Scotti, Diplolabis forensis, 444
Zygopteris primaria, Stauropteris oldhamia
309. Diplolabis forensis, Botryopteris forensis, Corynepteris coralloides, 445
Schizopteris pinnata
310. Metaclepsydropsis duplex, Stauropteris oldhamia, Ankyropteris 450
scandens
311. Ankyropteris Grayi 451
312. Thamnopteris Schlechtendalii, Ankyropteris corrugata, A. 453
bibractensis
313. Ankyropteris bibractensis 454
314. Ankyropteris corrugata 457
315. Ankyropteris corrugata 458
[Editor of the New Phytologist.]
316, 317. Ankyropteris corrugata 459, 460
Page 28
Fig. Page
318. Etapteris Scotti 462
[Editor of the New Phytologist.]
319. Etapteris, Botryopteris forensis 463
320. Stauropteris oldhamia 464
[Editor of the New Phytologist.]
321. Stauropteris oldhamia 467
322. Stauropteris oldhamia 468
[Editor of the New Phytologist.]
323. Stauropteris 469
[Editor of the New Phytologist.]
324. Asterochlaena laxa 472
[Editor of the New Phytologist.]
325. Sporocarp-like bodies (? Sagenopteris) 478
326. Regnellidium diphyllum, Sagenopteris rhoifolia 479
327. Sagenopteris Phillipsi 480
[Trustees of the British Museum.]
328. Sagenopteris Phillipsi 481
[Council of the Manchester Literary and Philosophical Society.]
329. Taeniopteris multinervis, Lesleya Delafondi 487
330. Taeniopteris Carnoti, T. spatulata, T. coriacea 490
331. Taeniopteris Carruthersi 491
[Annals of the South African Museum.]
332. Taeniopteris vittata 493
333. Weichselia Mantelli, W. erratica 495
334. Glossopteris Browniana 499
[Council of the Geological Society of London.]
335, 336. Glossopteris Browniana 500, 501
[Trustees of the British Museum.]
337. Vertebraria indica 502
338. Vertebraria indica, Onoclea struthiopteris 503
339. Glossopteris fronds attached to rhizome 504
340, 341. Glossopteris indica, G. angustifolia 506, 507
[Trustees of the British Museum.]
342. Glossopteris angustifolia var. taeniopteroides 508
[Council of the Geological Society.]
343. Blechnoxylon talbragarense 509
344. Glossopteris retifera 511
[Trustees of the British Museum.]
345. Gangamopteris cyclopteroides 515
[Trustees of the British Museum.]
346. Arberia sp. 517
347. Lesleya simplicinervis 518
318. Etapteris Scotti 462
[Editor of the New Phytologist.]
319. Etapteris, Botryopteris forensis 463
320. Stauropteris oldhamia 464
[Editor of the New Phytologist.]
321. Stauropteris oldhamia 467
322. Stauropteris oldhamia 468
[Editor of the New Phytologist.]
323. Stauropteris 469
[Editor of the New Phytologist.]
324. Asterochlaena laxa 472
[Editor of the New Phytologist.]
325. Sporocarp-like bodies (? Sagenopteris) 478
326. Regnellidium diphyllum, Sagenopteris rhoifolia 479
327. Sagenopteris Phillipsi 480
[Trustees of the British Museum.]
328. Sagenopteris Phillipsi 481
[Council of the Manchester Literary and Philosophical Society.]
329. Taeniopteris multinervis, Lesleya Delafondi 487
330. Taeniopteris Carnoti, T. spatulata, T. coriacea 490
331. Taeniopteris Carruthersi 491
[Annals of the South African Museum.]
332. Taeniopteris vittata 493
333. Weichselia Mantelli, W. erratica 495
334. Glossopteris Browniana 499
[Council of the Geological Society of London.]
335, 336. Glossopteris Browniana 500, 501
[Trustees of the British Museum.]
337. Vertebraria indica 502
338. Vertebraria indica, Onoclea struthiopteris 503
339. Glossopteris fronds attached to rhizome 504
340, 341. Glossopteris indica, G. angustifolia 506, 507
[Trustees of the British Museum.]
342. Glossopteris angustifolia var. taeniopteroides 508
[Council of the Geological Society.]
343. Blechnoxylon talbragarense 509
344. Glossopteris retifera 511
[Trustees of the British Museum.]
345. Gangamopteris cyclopteroides 515
[Trustees of the British Museum.]
346. Arberia sp. 517
347. Lesleya simplicinervis 518
Page 29
Fig. Page
348. Neuropteridium validum 520
[Trustees of the British Museum.]
349. Neuropteridium intermedium 522
350. Cardiopteris frondosa 524
351. Gunnera manicata 527
352. Sphenopteris obtusiloba, Pecopteris arborescens, Sphenopteris 529
furcata
353. Sphenopteris affinis 531
354. Palmatopteris, Mariopteris, Diplotmema Zeilleri, Neuropteris 535
macrophylla, N. heterophylla, N. Scheuchzeri, Alloiopteris
Essinghii
355. Cephalotheca mirabilis 536
356. Thinnfeldia odontopteroides, Ptilozamites 539
[Council of the Geological Society.]
357. Thinnfeldia odontopteroides 540
[Council of the Geological Society.]
358. Thinnfeldia odontopteroides 541
[Annals of the South African Museum.]
359. Thinnfeldia rhomboidalis 542
360. Lomatopteris jurensis, L. Schimperi, Thinnfeldia rhomboidalis 544
361. Ptilozamites Heeri 547
362. Ctenopteris cycadea 549
363. Dichopteris visianica 551
364. Alethopteris lonchitica, Mariopteris muricata, Odontopteris cf. 553
alpina
365. Odontopteris minor 554
366. Odontopteris genuina, Callipteridium gigas, Callipteris Pellati, C. 557
lyratifolia
367. Callipteris conferta 559
368. Archaeopteris hibernica 561
369. Archaeopteris hibernica, A. archetypus, A.fissilis, A. fimbriata 564
370. Neuropteris with Cyclopteris leaflets 566
[From a block received from Mr Carruthers.]
371. Neuropteris heterophylla 568
372. Neuropteris macrophylla 569
373. Neuropteris Scheuchzeri 570
374. Linopteris neuropteroides 573
375. Alethopteris Serlii 575
376. Pecopteris arborescens 578
348. Neuropteridium validum 520
[Trustees of the British Museum.]
349. Neuropteridium intermedium 522
350. Cardiopteris frondosa 524
351. Gunnera manicata 527
352. Sphenopteris obtusiloba, Pecopteris arborescens, Sphenopteris 529
furcata
353. Sphenopteris affinis 531
354. Palmatopteris, Mariopteris, Diplotmema Zeilleri, Neuropteris 535
macrophylla, N. heterophylla, N. Scheuchzeri, Alloiopteris
Essinghii
355. Cephalotheca mirabilis 536
356. Thinnfeldia odontopteroides, Ptilozamites 539
[Council of the Geological Society.]
357. Thinnfeldia odontopteroides 540
[Council of the Geological Society.]
358. Thinnfeldia odontopteroides 541
[Annals of the South African Museum.]
359. Thinnfeldia rhomboidalis 542
360. Lomatopteris jurensis, L. Schimperi, Thinnfeldia rhomboidalis 544
361. Ptilozamites Heeri 547
362. Ctenopteris cycadea 549
363. Dichopteris visianica 551
364. Alethopteris lonchitica, Mariopteris muricata, Odontopteris cf. 553
alpina
365. Odontopteris minor 554
366. Odontopteris genuina, Callipteridium gigas, Callipteris Pellati, C. 557
lyratifolia
367. Callipteris conferta 559
368. Archaeopteris hibernica 561
369. Archaeopteris hibernica, A. archetypus, A.fissilis, A. fimbriata 564
370. Neuropteris with Cyclopteris leaflets 566
[From a block received from Mr Carruthers.]
371. Neuropteris heterophylla 568
372. Neuropteris macrophylla 569
373. Neuropteris Scheuchzeri 570
374. Linopteris neuropteroides 573
375. Alethopteris Serlii 575
376. Pecopteris arborescens 578
Page 30
Page 31
ERRATA IN VOL. I
Page 16, line 4. For “The North American Tulip tree” read The Tulip
tree of North America and China.
„ 66, line 2 from the bottom. For “Browera” read Berowra.
„ 127, line 3 and 4 from bottom. For Achyla and Palaeachyla read
Achlya and Palaeachlya.
„ 145, lines 4 and 5. For “Upper Greensand” read Lower Eocene.
„ 162, line 3 from bottom. For “Corallina barbata” read
Cymopolia barbata.
„ 170, line 20. For “sporangiaphore” read sporangiophore.
„ 185, line 2. The genera Udotea and Halimeda, members of the
Siphoneae, are incorrectly included under the
Corallinaceae.
„ 191, line 11 from bottom. Omit Chondrus crispus, which is one
of the Florideae and not a Brown Alga.
„ 202, line 13. For “Halmeda” read Halimeda.
„ 250, line 11. For “three” read the.
„ 381, line 10. For “Calamopytus” read Calamopitys.
Page 16, line 4. For “The North American Tulip tree” read The Tulip
tree of North America and China.
„ 66, line 2 from the bottom. For “Browera” read Berowra.
„ 127, line 3 and 4 from bottom. For Achyla and Palaeachyla read
Achlya and Palaeachlya.
„ 145, lines 4 and 5. For “Upper Greensand” read Lower Eocene.
„ 162, line 3 from bottom. For “Corallina barbata” read
Cymopolia barbata.
„ 170, line 20. For “sporangiaphore” read sporangiophore.
„ 185, line 2. The genera Udotea and Halimeda, members of the
Siphoneae, are incorrectly included under the
Corallinaceae.
„ 191, line 11 from bottom. Omit Chondrus crispus, which is one
of the Florideae and not a Brown Alga.
„ 202, line 13. For “Halmeda” read Halimeda.
„ 250, line 11. For “three” read the.
„ 381, line 10. For “Calamopytus” read Calamopitys.
Page 32
Page 33
CHAPTER XII[1].
SPHENOPHYLLALES (concluded).
Sphenophyllum.
The account of the Sphenophyllales given in the first volume[2] of this
work must be extended and somewhat modified in the light of recent work
on the fertile shoots of Sphenophyllum.
Sphenophyllostachys Dawsoni (Will.) was described as consisting of an
axis bearing superposed whorls of bracts connate at the base in the form of
a shallow funnel-shaped collar giving off from the upper surface and close
to the axis of the cone two concentric series of sporangiophores.
Occasionally there are three series, as represented in fig. 112. In another
type of strobilus, Sphenophyllostachys Römeri[3] each sporangiophore
terminates in two pendulous sporangia (fig. 113, A; see also fig. 107, C, vol.
i.). It has already been pointed out that the common occurrence of detached
strobili necessitates their description under distinct specific names; it is only
by a rare accident that we can assign fossil cones to their vegetative shoots.
There are, however, reasons for believing that Sphenophyllostachys
Dawsoni is the strobilus of the plant originally described by Sternberg[4]
from impressions of foliage-shoots as Rotularia cuneifolia. Another
difficulty presented by petrified material is that of determining, with
certainty, whether two imperfect specimens, differing from one another in
features which do not appear to be of sufficient importance to warrant
specific separation, are forms of one species or portions of specifically
distinct cones. It has been pointed out by Scott[5] that the strobilus known as
Sphenophyllostachys Dawsoni probably includes two distinct species, one
being the cone of Sphenophyllum cuneifolium Sternb., and the other the
cone of S. myriophyllum Crép[6]. The stem of S. myriophyllum agrees
anatomically with the type known as Sphenophyllum plurifoliatum Will.
and Scott[7].
SPHENOPHYLLALES (concluded).
Sphenophyllum.
The account of the Sphenophyllales given in the first volume[2] of this
work must be extended and somewhat modified in the light of recent work
on the fertile shoots of Sphenophyllum.
Sphenophyllostachys Dawsoni (Will.) was described as consisting of an
axis bearing superposed whorls of bracts connate at the base in the form of
a shallow funnel-shaped collar giving off from the upper surface and close
to the axis of the cone two concentric series of sporangiophores.
Occasionally there are three series, as represented in fig. 112. In another
type of strobilus, Sphenophyllostachys Römeri[3] each sporangiophore
terminates in two pendulous sporangia (fig. 113, A; see also fig. 107, C, vol.
i.). It has already been pointed out that the common occurrence of detached
strobili necessitates their description under distinct specific names; it is only
by a rare accident that we can assign fossil cones to their vegetative shoots.
There are, however, reasons for believing that Sphenophyllostachys
Dawsoni is the strobilus of the plant originally described by Sternberg[4]
from impressions of foliage-shoots as Rotularia cuneifolia. Another
difficulty presented by petrified material is that of determining, with
certainty, whether two imperfect specimens, differing from one another in
features which do not appear to be of sufficient importance to warrant
specific separation, are forms of one species or portions of specifically
distinct cones. It has been pointed out by Scott[5] that the strobilus known as
Sphenophyllostachys Dawsoni probably includes two distinct species, one
being the cone of Sphenophyllum cuneifolium Sternb., and the other the
cone of S. myriophyllum Crép[6]. The stem of S. myriophyllum agrees
anatomically with the type known as Sphenophyllum plurifoliatum Will.
and Scott[7].
Page 34
Fig. 112. Sketch of a radial longitudinal section of Sphenophyllostachys. There are usually
two concentric series of sporangia on the sporophylls, not three as shown in the
figure. The upper figure (after Zeiller) shows the linear bracts in surface-view.
In addition to the two types of cone already mentioned,
Sphenophyllostachys Dawsoni and S. Römeri, others have been described
by Kidston from carbonised impressions. One of these is the fertile branch
of Sphenophyllum majus[8]. The basal portions of the bracts of each whorl
form a narrow collar round the axis of the cone; the free portion of each
bract consists of a lamina divided into two equal bifid lobes bearing on its
upper surface one group, or possibly two groups, of four sessile sporangia
between the narrow coherent bases of the laminae and the sinus between the
terminal lobes (fig. 113, C). Another characteristic feature is the greater
length of the internodes; this renders the cone less compact and less sharply
differentiated from the vegetative shoots than those of other species. A
specimen in Dr Kidston’s collection illustrates the peculiar character of the
fertile portion of this species; it consists of an axis bearing a succession of
lax sporophylls succeeded above and below by whorls of sterile leaves. In
this species, therefore, we cannot speak of a compact strobilus at the end of
a shoot of limited growth, but of axes in which sterile and fertile leaves are
two concentric series of sporangia on the sporophylls, not three as shown in the
figure. The upper figure (after Zeiller) shows the linear bracts in surface-view.
In addition to the two types of cone already mentioned,
Sphenophyllostachys Dawsoni and S. Römeri, others have been described
by Kidston from carbonised impressions. One of these is the fertile branch
of Sphenophyllum majus[8]. The basal portions of the bracts of each whorl
form a narrow collar round the axis of the cone; the free portion of each
bract consists of a lamina divided into two equal bifid lobes bearing on its
upper surface one group, or possibly two groups, of four sessile sporangia
between the narrow coherent bases of the laminae and the sinus between the
terminal lobes (fig. 113, C). Another characteristic feature is the greater
length of the internodes; this renders the cone less compact and less sharply
differentiated from the vegetative shoots than those of other species. A
specimen in Dr Kidston’s collection illustrates the peculiar character of the
fertile portion of this species; it consists of an axis bearing a succession of
lax sporophylls succeeded above and below by whorls of sterile leaves. In
this species, therefore, we cannot speak of a compact strobilus at the end of
a shoot of limited growth, but of axes in which sterile and fertile leaves are
Page 35
borne alternately[9], a condition recalling the alternation of foliage leaves
and sporophylls in Tmesipteris and in Lycopodium Selago.
Fig. 113.
A. Sphenophyllostachys Römeri. (Solms-Laubach.)
B. Sphenophyllum trichomatosum Stur.
C. Sphenophyllum majus. Bronn. (A–C. After Kidston.)
Another form of cone, also from the Middle Coal Measures, is referred
by Kidston to Sphenophyllum trichomatosum Stur[10] (fig. 113, B): this is
characterised by the more horizontal position of the bracts, which “do not
appear to be so much or so suddenly bent upwards in their distal portion as
in some other species of Sphenophyllum,” and by sessile sporangia borne
singly on the upper face of each bract.
and sporophylls in Tmesipteris and in Lycopodium Selago.
Fig. 113.
A. Sphenophyllostachys Römeri. (Solms-Laubach.)
B. Sphenophyllum trichomatosum Stur.
C. Sphenophyllum majus. Bronn. (A–C. After Kidston.)
Another form of cone, also from the Middle Coal Measures, is referred
by Kidston to Sphenophyllum trichomatosum Stur[10] (fig. 113, B): this is
characterised by the more horizontal position of the bracts, which “do not
appear to be so much or so suddenly bent upwards in their distal portion as
in some other species of Sphenophyllum,” and by sessile sporangia borne
singly on the upper face of each bract.
Page 36
Fig. 114. Sphenophyllostachys fertilis (Scott). (After Scott.) Diagram of a node in
longitudinal section, showing one sporophyll and the base of the opposite one. v.l.
ventral lobe of sporophyll; v.s. one of the segments into which it divides; v.s′.
stump of another segment; d.l. dorsal lobe; d.s., d.s′. segments of dorsal lobe.
A more recent addition to our knowledge of the fertile shoots of
Sphenophyllum is due to Scott who has described a new type of cone under
the name Sphenophyllum fertile[11]. The petrified specimen on which the
species was founded was discovered by Mr James Lomax in the Lower
Coal Measures of Lancashire; it represents a portion of a cone 6 cm. long
and approximately 12 mm. broad. The axis contains a single vascular
cylinder agreeing in essentials with the type of stem structure known as
Sphenophyllum plurifoliatum. The nodal regions, which exhibit the slight
swelling characteristic of the genus, bear several (probably twelve)
appendages connate at the base and forming a narrow flange encircling the
axis. Each bract, the base of which forms part of the narrow collar
surrounding the axis, consists of two lobes, ventral and dorsal, divided
palmately into several (sometimes four) segments or sporangiophores (fig.
115). Each sporangiophore terminates distally in an oblong or oval lamina
bearing two sporangia on its adaxial face (fig. 114). The space between the
axis and the periphery of the cone is thus occupied by crowded peltate
laminae, each with its pair of sporangia. A single vascular bundle supplies
each sporangiophore and bifurcates in the distal lamina into two branches
which extend to the bases of the sporangia. The sporangia agree in structure
with those of other species of Sphenophyllum: the spores are of one size and
elliptical, characterised by the presence of several sharp ridges or flanges
encircling the spore-wall in the direction of the major-axis.
Sphenophyllostachys fertilis differs from all previously recorded types in
the absence of sterile bracts. The appendages of the cone-axis are all fertile,
longitudinal section, showing one sporophyll and the base of the opposite one. v.l.
ventral lobe of sporophyll; v.s. one of the segments into which it divides; v.s′.
stump of another segment; d.l. dorsal lobe; d.s., d.s′. segments of dorsal lobe.
A more recent addition to our knowledge of the fertile shoots of
Sphenophyllum is due to Scott who has described a new type of cone under
the name Sphenophyllum fertile[11]. The petrified specimen on which the
species was founded was discovered by Mr James Lomax in the Lower
Coal Measures of Lancashire; it represents a portion of a cone 6 cm. long
and approximately 12 mm. broad. The axis contains a single vascular
cylinder agreeing in essentials with the type of stem structure known as
Sphenophyllum plurifoliatum. The nodal regions, which exhibit the slight
swelling characteristic of the genus, bear several (probably twelve)
appendages connate at the base and forming a narrow flange encircling the
axis. Each bract, the base of which forms part of the narrow collar
surrounding the axis, consists of two lobes, ventral and dorsal, divided
palmately into several (sometimes four) segments or sporangiophores (fig.
115). Each sporangiophore terminates distally in an oblong or oval lamina
bearing two sporangia on its adaxial face (fig. 114). The space between the
axis and the periphery of the cone is thus occupied by crowded peltate
laminae, each with its pair of sporangia. A single vascular bundle supplies
each sporangiophore and bifurcates in the distal lamina into two branches
which extend to the bases of the sporangia. The sporangia agree in structure
with those of other species of Sphenophyllum: the spores are of one size and
elliptical, characterised by the presence of several sharp ridges or flanges
encircling the spore-wall in the direction of the major-axis.
Sphenophyllostachys fertilis differs from all previously recorded types in
the absence of sterile bracts. The appendages of the cone-axis are all fertile,
Page 37
a striking contrast to the differentiation into protective and sporangia-
bearing bracts which constitutes a constant feature in the cones of
Sphenophyllum and Calamites. It is possible, as Scott suggests, that the
absence of sterile segments is the result of modification of the more usual
type of strobilus; instead of the dorsal and ventral lobes of the bracts
sharing between them the duties of protection and spore-production, the
whole of each bract is constructed on the plan of the maximum spore-
output, the laminar terminations of the sporangiophores serving the purpose
of protection. The cone may be described as more specialised than the
normal type of strobilus for reproductive purposes[12].
Fig. 115. Sphenophyllostachys fertilis (Scott). (After Scott.) Diagram of a single sporophyll
as it would appear in a transverse section of the cone; showing one lobe (dorsal or
ventral). ax, part of axis to which the sporophylls are attached.
bearing bracts which constitutes a constant feature in the cones of
Sphenophyllum and Calamites. It is possible, as Scott suggests, that the
absence of sterile segments is the result of modification of the more usual
type of strobilus; instead of the dorsal and ventral lobes of the bracts
sharing between them the duties of protection and spore-production, the
whole of each bract is constructed on the plan of the maximum spore-
output, the laminar terminations of the sporangiophores serving the purpose
of protection. The cone may be described as more specialised than the
normal type of strobilus for reproductive purposes[12].
Fig. 115. Sphenophyllostachys fertilis (Scott). (After Scott.) Diagram of a single sporophyll
as it would appear in a transverse section of the cone; showing one lobe (dorsal or
ventral). ax, part of axis to which the sporophylls are attached.
Page 38
Fig. 116. Sphenophyllostachys Dawsoni. (After Thoday.) A. Larger spores; B, abortive
spores; C, mature spores showing the characteristic spines.
It has been stated, on evidence which is unsatisfactory, that
Sphenophyllum possesses two kinds of spores. While regarding the genus as
homosporous on the evidence before us, it is interesting to find that cases
occur in which the spores in the same sporangium exhibit a marked
difference in size. Attention has been called by Williamson and Scott[13] to
variation in the dimensions of spores: a more pronounced difference in size
has been recorded by Mr Thoday[14] who gives 120μ as the maximum and
90μ as the minimum diameter of the spores in a cone of
Sphenophyllostachys Dawsoni. The presence of several abortive spores in
the sporangium (fig. 116) containing the larger spores favours the view that
this difference in size may be the first step towards the development of
heterospory.
It is clear that the types of strobilus designated Sphenophyllostachys
(figs. 112–114) present a divergence of characters too great to be comprised
under one genus; but in the absence of fuller information, we cannot do
otherwise than follow the only logical custom of grouping them together as
examples of strobili borne by plants which, in the present state of our
knowledge, are most conveniently referred to the genus Sphenophyllum.
Cheirostrobus.
spores; C, mature spores showing the characteristic spines.
It has been stated, on evidence which is unsatisfactory, that
Sphenophyllum possesses two kinds of spores. While regarding the genus as
homosporous on the evidence before us, it is interesting to find that cases
occur in which the spores in the same sporangium exhibit a marked
difference in size. Attention has been called by Williamson and Scott[13] to
variation in the dimensions of spores: a more pronounced difference in size
has been recorded by Mr Thoday[14] who gives 120μ as the maximum and
90μ as the minimum diameter of the spores in a cone of
Sphenophyllostachys Dawsoni. The presence of several abortive spores in
the sporangium (fig. 116) containing the larger spores favours the view that
this difference in size may be the first step towards the development of
heterospory.
It is clear that the types of strobilus designated Sphenophyllostachys
(figs. 112–114) present a divergence of characters too great to be comprised
under one genus; but in the absence of fuller information, we cannot do
otherwise than follow the only logical custom of grouping them together as
examples of strobili borne by plants which, in the present state of our
knowledge, are most conveniently referred to the genus Sphenophyllum.
Cheirostrobus.
Page 39
This generic name was applied by Dr Scott[15] to a calcified cone obtained
by Mr James Bennie in 1883 from the Lower Carboniferous plant-beds of
Pettycur near Burntisland on the Firth of Forth. Cheirostrobus is
distinguished from Sphenophyllostachys by its greater breadth (3.5 cm.);
externally it agrees more closely with the fertile shoots of Lepidodendron
than with those of Sphenophyllum. A single vascular cylinder having the
form of a fluted Doric column (fig. 117, B, x) occupies the axis of the cone:
it consists for the most part of reticulate tracheae which tend to assume a
short or isodiametric form in the central region; the smaller protoxylem
tracheids with the spiral form of pitting constitute the sharp and prominent
ridges at the periphery of the xylem-cylinder. In the outer part of the
cylinder the metaxylem[16] consists exclusively of tracheae, but towards the
centre of the axis these are associated with numerous parenchymatous cells.
The xylem is therefore centripetal in origin as in Sphenophyllum and in
nearly all recent and fossil members of the Lycopodiales. In the type-
specimen of Cheirostrobus the vascular cylinder of the cone consists
entirely of primary xylem, but secondary xylem has been found in a more
recently discovered specimen[17]. Secondary xylem occurs also in the
peduncle of the cone. No appreciable remains of phloem have been found.
The cortex consists of slightly elongated rather thick-walled tissue
containing secretory sacs. Crowded superposed whorls of bracts (or
sporophylls), usually twelve in each whorl, are borne on the axis and each
sporophyll receives a single vascular bundle from one of the vertical ridges
of the xylem column (fig. 117, A, lt). The members of each whorl are
connate at the base: from this narrow collar each sporophyll branches into
an upper or dorsal and a lower or ventral limb (fig. 117, A, f and s). Each
limb divides palmately at a short distance from its origin into three slender
segments, which extend in a horizontal direction and terminate in large
laminar expansions (fig. 117, B, s) to afford a protective covering to the
surface of the cone. The upper set of three segments, constituting
sporangiophores (fig. 117, A, B, f) or fertile divisions of the sporophyll,
expand distally into comparatively bulky laminae; each of these bears on its
adaxial face four diagonally placed outgrowths which form the short
pedicels of very long and narrow sporangia. The three lower segments—the
sterile divisions of the sporophylls—(fig. 117, A, B, s) are similar to the
upper set except in their greater length and in the kite-shaped form of their
distal laminae which are provided with lateral lobes. The single vascular
by Mr James Bennie in 1883 from the Lower Carboniferous plant-beds of
Pettycur near Burntisland on the Firth of Forth. Cheirostrobus is
distinguished from Sphenophyllostachys by its greater breadth (3.5 cm.);
externally it agrees more closely with the fertile shoots of Lepidodendron
than with those of Sphenophyllum. A single vascular cylinder having the
form of a fluted Doric column (fig. 117, B, x) occupies the axis of the cone:
it consists for the most part of reticulate tracheae which tend to assume a
short or isodiametric form in the central region; the smaller protoxylem
tracheids with the spiral form of pitting constitute the sharp and prominent
ridges at the periphery of the xylem-cylinder. In the outer part of the
cylinder the metaxylem[16] consists exclusively of tracheae, but towards the
centre of the axis these are associated with numerous parenchymatous cells.
The xylem is therefore centripetal in origin as in Sphenophyllum and in
nearly all recent and fossil members of the Lycopodiales. In the type-
specimen of Cheirostrobus the vascular cylinder of the cone consists
entirely of primary xylem, but secondary xylem has been found in a more
recently discovered specimen[17]. Secondary xylem occurs also in the
peduncle of the cone. No appreciable remains of phloem have been found.
The cortex consists of slightly elongated rather thick-walled tissue
containing secretory sacs. Crowded superposed whorls of bracts (or
sporophylls), usually twelve in each whorl, are borne on the axis and each
sporophyll receives a single vascular bundle from one of the vertical ridges
of the xylem column (fig. 117, A, lt). The members of each whorl are
connate at the base: from this narrow collar each sporophyll branches into
an upper or dorsal and a lower or ventral limb (fig. 117, A, f and s). Each
limb divides palmately at a short distance from its origin into three slender
segments, which extend in a horizontal direction and terminate in large
laminar expansions (fig. 117, B, s) to afford a protective covering to the
surface of the cone. The upper set of three segments, constituting
sporangiophores (fig. 117, A, B, f) or fertile divisions of the sporophyll,
expand distally into comparatively bulky laminae; each of these bears on its
adaxial face four diagonally placed outgrowths which form the short
pedicels of very long and narrow sporangia. The three lower segments—the
sterile divisions of the sporophylls—(fig. 117, A, B, s) are similar to the
upper set except in their greater length and in the kite-shaped form of their
distal laminae which are provided with lateral lobes. The single vascular
Page 40
strand which supplies each sporophyll is represented at lt in fig. 117, B; at
lt′ the strand has divided into four, the three upper bundles in the figure
supply the sterile segments and the single lower bundle ultimately divides
into three which supply the fertile segments. A pair of blunt processes (fig.
A, s) extend downwards over the ends of the underlying fertile lamina and
two slender prolongations extend upwards through several internodes.
Fig. 117. A, B. Cheirostrobus pettycurensis Scott. (After Scott.)
C, D. Pseudobornia ursina Nath. (After Nathorst.)
A. Diagrammatic radial longitudinal section of part of the cone-axis and two
sporophylls. lt, bundle passing out to sporophyll; f, fertile segment of sporophyll
showing two sporangia; s, sterile (lower) segment.
B. Part of transverse section. x, stele; lt, lt′, bundles on their way to sporophylls; a,
tips of sterile segments of lower sporophylls.
C. Palmately branched leaf (½ natural size).
D. Node of stem showing leaf-bases.
An economical arrangement of the long and narrow sporangia and of the
sporophyll-segments between the axis and the periphery of the cone is
rendered possible by the interlocking of the sterile and fertile segments by
lt′ the strand has divided into four, the three upper bundles in the figure
supply the sterile segments and the single lower bundle ultimately divides
into three which supply the fertile segments. A pair of blunt processes (fig.
A, s) extend downwards over the ends of the underlying fertile lamina and
two slender prolongations extend upwards through several internodes.
Fig. 117. A, B. Cheirostrobus pettycurensis Scott. (After Scott.)
C, D. Pseudobornia ursina Nath. (After Nathorst.)
A. Diagrammatic radial longitudinal section of part of the cone-axis and two
sporophylls. lt, bundle passing out to sporophyll; f, fertile segment of sporophyll
showing two sporangia; s, sterile (lower) segment.
B. Part of transverse section. x, stele; lt, lt′, bundles on their way to sporophylls; a,
tips of sterile segments of lower sporophylls.
C. Palmately branched leaf (½ natural size).
D. Node of stem showing leaf-bases.
An economical arrangement of the long and narrow sporangia and of the
sporophyll-segments between the axis and the periphery of the cone is
rendered possible by the interlocking of the sterile and fertile segments by
Page 41
means of a groove in the upper face of the latter for the accommodation of
the former. The sporangia are characterised by their unusually long and
narrow form: the length of a sporangium may reach 1 centimetre. In the
structure of the wall the sporangia of Cheirostrobus agree closely with those
of Calamostachys[18] and Sphenophyllostachys. The spores are of one size
only. The vascular cylinder of the peduncle, originally described by
Williamson[19] as the peduncle of a large Lepidostrobus (the cone of
Lepidodendron), is characterised by the presence of a short radially
disposed zone of secondary tracheids, a feature, as Scott points out, which
may extend into the axis of the cone. It is noteworthy that the protoxylem
elements are not always external, but occasionally occur internal to one or
two of the outermost metaxylem tracheae: the usual exarch[20] structure of
the central cylinder is not therefore absolutely constant, but may be
replaced by a mesarch arrangement.
The presence of a few sterile leaves on the peduncle below the fertile
portion of the cone, which agree in their lobed laminae with the
sporophylls, is the only fact which we possess as to the form of the
vegetative characters of the genus.
The above description is sufficient to indicate the extraordinary
complexity and high degree of specialisation of Cheirostrobus. The
sporophylls, with their trilobed segments, and the crowded sporangia of
exceptional length attached only by a narrow base constitute striking
peculiarities of the genus.
It is unfortunate that we are still without any satisfactory evidence as to
the nature of the plant the cones of which have been made the type of a new
genus and a new family. Cheirostrobus affords an interesting example of a
type of reproductive shoot constructed on a plan sui generis, and may be
classed with some other extinct genera as instances of the production in the
course of evolution of architectural schemes which appear to have been ill
adapted for competition with equally efficient though much simpler types.
But the discovery of these isolated forms of restricted geological range
among the relics of the Palaeozoic vegetation frequently supplies a key to
phylogenetic problems. Cheirostrobus by its complex combination of
features characteristic of the Equisetales, the Lycopodiales and the genus
Sphenophyllum throws a welcome light on the inter-relationships of groups
which represent divergent series. The combination of morphological
the former. The sporangia are characterised by their unusually long and
narrow form: the length of a sporangium may reach 1 centimetre. In the
structure of the wall the sporangia of Cheirostrobus agree closely with those
of Calamostachys[18] and Sphenophyllostachys. The spores are of one size
only. The vascular cylinder of the peduncle, originally described by
Williamson[19] as the peduncle of a large Lepidostrobus (the cone of
Lepidodendron), is characterised by the presence of a short radially
disposed zone of secondary tracheids, a feature, as Scott points out, which
may extend into the axis of the cone. It is noteworthy that the protoxylem
elements are not always external, but occasionally occur internal to one or
two of the outermost metaxylem tracheae: the usual exarch[20] structure of
the central cylinder is not therefore absolutely constant, but may be
replaced by a mesarch arrangement.
The presence of a few sterile leaves on the peduncle below the fertile
portion of the cone, which agree in their lobed laminae with the
sporophylls, is the only fact which we possess as to the form of the
vegetative characters of the genus.
The above description is sufficient to indicate the extraordinary
complexity and high degree of specialisation of Cheirostrobus. The
sporophylls, with their trilobed segments, and the crowded sporangia of
exceptional length attached only by a narrow base constitute striking
peculiarities of the genus.
It is unfortunate that we are still without any satisfactory evidence as to
the nature of the plant the cones of which have been made the type of a new
genus and a new family. Cheirostrobus affords an interesting example of a
type of reproductive shoot constructed on a plan sui generis, and may be
classed with some other extinct genera as instances of the production in the
course of evolution of architectural schemes which appear to have been ill
adapted for competition with equally efficient though much simpler types.
But the discovery of these isolated forms of restricted geological range
among the relics of the Palaeozoic vegetation frequently supplies a key to
phylogenetic problems. Cheirostrobus by its complex combination of
features characteristic of the Equisetales, the Lycopodiales and the genus
Sphenophyllum throws a welcome light on the inter-relationships of groups
which represent divergent series. The combination of morphological
Page 42
features in this generalised type led the author of the genus to describe it as
a descendant of an old stock which existed prior to the divergence of the
Equisetales and Lycopodiales.
The discovery of this new type of strobilus naturally led to a search
among Lower Carboniferous plants for vegetative shoots exhibiting
characters conformable with the whorled and branched leaves of
Cheirostrobus. In Sphenophyllum we have a genus obviously comparable
with Cheirostrobus as regards the form and disposition of the leaves, but the
differences between the cones and the striking similarity of the vascular
cylinder of the latter to that of Lepidodendron demonstrate conclusively that
we must look elsewhere for the vegetative members of the plant which
produced cones of the Cheirostrobus type.
PSEUDOBORNIA
In 1902 Professor Nathorst[21] instituted the generic name Pseudobornia
for plants of which imperfect examples had previously been referred by
Heer[22] to Calamites under the name C. radiatus. Heer’s plants were
obtained from Upper Devonian rocks of Bear Island in the Arctic seas and
additional specimens were brought from the same locality by the Swedish
Polar Expedition of 1898. Pseudobornia possesses jointed stems (fig. 117,
D) bearing whorled and shortly stalked leaves, often four in number, at each
node. The leaves are palmately branched with fine serrated edges (fig. 117,
C). Certain specimens, which are no doubt correctly described by Nathorst
as cones, are characterised by a thick axis bearing whorled leaves with
sporangia on their lower surfaces, but the material is not sufficiently well
preserved to render possible a recognition of structural details. It has been
suggested by Scott that Pseudobornia may possibly be referable to the
Sphenophyllales and that the stem of Cheirostrobus “may have had
something in common with” Nathorst’s genus[23]. The beds in which the
stems occur are of Upper Devonian age, while Cheirostrobus was found in
Lower Carboniferous rocks: this difference in age is not, however, a serious
objection to the validity of the comparison. We cannot do more than express
the view that Pseudobornia, so far as can be ascertained without an
examination of petrified material or of more perfect impressions of strobili,
exhibits vegetative features not inconsistent with the morphological
characters of the fertile shoots known as Cheirostrobus.
• • • • •
a descendant of an old stock which existed prior to the divergence of the
Equisetales and Lycopodiales.
The discovery of this new type of strobilus naturally led to a search
among Lower Carboniferous plants for vegetative shoots exhibiting
characters conformable with the whorled and branched leaves of
Cheirostrobus. In Sphenophyllum we have a genus obviously comparable
with Cheirostrobus as regards the form and disposition of the leaves, but the
differences between the cones and the striking similarity of the vascular
cylinder of the latter to that of Lepidodendron demonstrate conclusively that
we must look elsewhere for the vegetative members of the plant which
produced cones of the Cheirostrobus type.
PSEUDOBORNIA
In 1902 Professor Nathorst[21] instituted the generic name Pseudobornia
for plants of which imperfect examples had previously been referred by
Heer[22] to Calamites under the name C. radiatus. Heer’s plants were
obtained from Upper Devonian rocks of Bear Island in the Arctic seas and
additional specimens were brought from the same locality by the Swedish
Polar Expedition of 1898. Pseudobornia possesses jointed stems (fig. 117,
D) bearing whorled and shortly stalked leaves, often four in number, at each
node. The leaves are palmately branched with fine serrated edges (fig. 117,
C). Certain specimens, which are no doubt correctly described by Nathorst
as cones, are characterised by a thick axis bearing whorled leaves with
sporangia on their lower surfaces, but the material is not sufficiently well
preserved to render possible a recognition of structural details. It has been
suggested by Scott that Pseudobornia may possibly be referable to the
Sphenophyllales and that the stem of Cheirostrobus “may have had
something in common with” Nathorst’s genus[23]. The beds in which the
stems occur are of Upper Devonian age, while Cheirostrobus was found in
Lower Carboniferous rocks: this difference in age is not, however, a serious
objection to the validity of the comparison. We cannot do more than express
the view that Pseudobornia, so far as can be ascertained without an
examination of petrified material or of more perfect impressions of strobili,
exhibits vegetative features not inconsistent with the morphological
characters of the fertile shoots known as Cheirostrobus.
• • • • •
Page 43
The institution of a special group-name for the reception of
Sphenophyllum is justified by the sum of its morphological features, which
do not sufficiently conform to those of any existing group of Pteridophytes
to warrant its inclusion in a system of classification based on recent genera.
In the case of Cheirostrobus we are limited to the characters of the cone and
its peduncle. The suggestion that the Devonian fossils known as
Pseudobornia may represent the foliage shoots of a plant closely related to
Cheirostrobus has still to be proved correct. Although we may find
justification in the highly complex and peculiar structure of Cheirostrobus
for the recognition of the genus as a type of still another group of
Pteridophytes, it would be unwise to take this step without additional
knowledge.
The undoubted similarity between Cheirostrobus and Sphenophyllum
coupled with striking points of difference favours the inclusion of the two
genera in distinct families placed, for the present at least, in the group
Sphenophyllales.
Group SPHENOPHYLLALES.
Sphenophylleae: genus Sphenophyllum.
Cheirostrobeae: genus Cheirostrobus.
It has recently been proposed to include the family Psilotaceae,
comprising the two recent genera Psilotum and Tmesipteris, as another
subdivision of the Sphenophyllales. This proposal had been made by
Professor Thomas[24] primarily on the ground that the sporophylls of
Tmesipteris and Psilotum appear to afford the closest parallel among
existing plants to the peculiar form of sporophyll characteristic of the
Sphenophyllales. The morphological interpretation of the sporophylls of
both Sphenophyllum and Cheirostrobus has been the source of considerable
discussion[25]. If we regard each sporophyll as a leaf with two lobes, one
fertile and one sterile, except in the case of Sphenophyllostachys fertilis in
which both are fertile, an obvious comparison may be made with the fern
Ophioglossum; but the difference between a single fern frond, consisting of
a comparatively large sterile lamina bearing a fertile branch composed of a
Sphenophyllum is justified by the sum of its morphological features, which
do not sufficiently conform to those of any existing group of Pteridophytes
to warrant its inclusion in a system of classification based on recent genera.
In the case of Cheirostrobus we are limited to the characters of the cone and
its peduncle. The suggestion that the Devonian fossils known as
Pseudobornia may represent the foliage shoots of a plant closely related to
Cheirostrobus has still to be proved correct. Although we may find
justification in the highly complex and peculiar structure of Cheirostrobus
for the recognition of the genus as a type of still another group of
Pteridophytes, it would be unwise to take this step without additional
knowledge.
The undoubted similarity between Cheirostrobus and Sphenophyllum
coupled with striking points of difference favours the inclusion of the two
genera in distinct families placed, for the present at least, in the group
Sphenophyllales.
Group SPHENOPHYLLALES.
Sphenophylleae: genus Sphenophyllum.
Cheirostrobeae: genus Cheirostrobus.
It has recently been proposed to include the family Psilotaceae,
comprising the two recent genera Psilotum and Tmesipteris, as another
subdivision of the Sphenophyllales. This proposal had been made by
Professor Thomas[24] primarily on the ground that the sporophylls of
Tmesipteris and Psilotum appear to afford the closest parallel among
existing plants to the peculiar form of sporophyll characteristic of the
Sphenophyllales. The morphological interpretation of the sporophylls of
both Sphenophyllum and Cheirostrobus has been the source of considerable
discussion[25]. If we regard each sporophyll as a leaf with two lobes, one
fertile and one sterile, except in the case of Sphenophyllostachys fertilis in
which both are fertile, an obvious comparison may be made with the fern
Ophioglossum; but the difference between a single fern frond, consisting of
a comparatively large sterile lamina bearing a fertile branch composed of a
Page 44
long axis with two rows of sporangia embedded in its tissues, and the
whorled sporophylls of Sphenophyllum is considerable.
PSILOTACEAE
A brief reference may be made to the principal reasons which have led to
the suggestion that the Psilotaceae should be included in the
Sphenophyllales. The shoots of Tmesipteris bear simple foliage leaves
spirally disposed on a slender axis, and in association with these occur
sporophylls consisting of a short axis bearing a pair of small lobes and a
bilocular synangium[26] (fig. 120, B). The synangium is seated on a very
short stalk given off from its sporophyll at the base of the pair of laminae:
the synangium with its short stalk may be spoken of as the sporangiophore.
In most cases the synangium appears to be sessile on the sporophyll, but
occasionally the much reduced stalk is prolonged and forms an obvious
feature. Dr Scott[27] suggested that the Tmesipteris synangium with its axis
may correspond to the ventral lobe (or sporangiophore) of Sphenophyllum.
In the latter genus the whorled sporophylls consist in most species of a
dorsal and a ventral lobe, the latter serving as a sporangiophore bearing one
or more sporangia; in Tmesipteris the sporophylls are spirally disposed and
each consists of a bilobed sterile portion bearing a septate sporangium or
bilocular synangium on a very short ventral lobe. Professor Bower[28], in his
account of the development and structure of the sporophylls of Tmesipteris,
drew attention to the comparatively frequent occurrence of abnormal
sporophylls and spoke of the plant as unstable. More recently Professor
Thomas[29] of Auckland has carefully examined living plants, with the result
that variations of different kinds are proved to be exceedingly common. He
finds that sporophylls occur which exhibit repeated dichotomy of the axis
(fig. 120, D, F) and thus each may bear four instead of two leaf-lobes and
three synangia, one at the first fork and one at each of the forks of the
second order[30].
Other abnormalities occur in which the synangium is raised on a distinct
stalk instead of being more or less sessile at the point from which the leaf-
lobes diverge. A third form of departure from the normal is that in which
there is no synangium on the bilobed sporophyll, its place being taken by a
leaf-lobe. The deduction from the occurrence of these abnormalities is that
the synangium of Tmesipteris represents a ventral leaf-lobe, as Scott
suggested. Professor Thomas draws attention to the resemblance between
whorled sporophylls of Sphenophyllum is considerable.
PSILOTACEAE
A brief reference may be made to the principal reasons which have led to
the suggestion that the Psilotaceae should be included in the
Sphenophyllales. The shoots of Tmesipteris bear simple foliage leaves
spirally disposed on a slender axis, and in association with these occur
sporophylls consisting of a short axis bearing a pair of small lobes and a
bilocular synangium[26] (fig. 120, B). The synangium is seated on a very
short stalk given off from its sporophyll at the base of the pair of laminae:
the synangium with its short stalk may be spoken of as the sporangiophore.
In most cases the synangium appears to be sessile on the sporophyll, but
occasionally the much reduced stalk is prolonged and forms an obvious
feature. Dr Scott[27] suggested that the Tmesipteris synangium with its axis
may correspond to the ventral lobe (or sporangiophore) of Sphenophyllum.
In the latter genus the whorled sporophylls consist in most species of a
dorsal and a ventral lobe, the latter serving as a sporangiophore bearing one
or more sporangia; in Tmesipteris the sporophylls are spirally disposed and
each consists of a bilobed sterile portion bearing a septate sporangium or
bilocular synangium on a very short ventral lobe. Professor Bower[28], in his
account of the development and structure of the sporophylls of Tmesipteris,
drew attention to the comparatively frequent occurrence of abnormal
sporophylls and spoke of the plant as unstable. More recently Professor
Thomas[29] of Auckland has carefully examined living plants, with the result
that variations of different kinds are proved to be exceedingly common. He
finds that sporophylls occur which exhibit repeated dichotomy of the axis
(fig. 120, D, F) and thus each may bear four instead of two leaf-lobes and
three synangia, one at the first fork and one at each of the forks of the
second order[30].
Other abnormalities occur in which the synangium is raised on a distinct
stalk instead of being more or less sessile at the point from which the leaf-
lobes diverge. A third form of departure from the normal is that in which
there is no synangium on the bilobed sporophyll, its place being taken by a
leaf-lobe. The deduction from the occurrence of these abnormalities is that
the synangium of Tmesipteris represents a ventral leaf-lobe, as Scott
suggested. Professor Thomas draws attention to the resemblance between
Page 45
Tmesipteris sporophylls and the foliage-leaves of Sphenophyllum, which are
either simple with dichotomously branched veins or the lamina is deeply
divided into two or more segments. In some types of Sphenophyllostachys
the bracts are simple (S. Dawsoni), but in others (Sphenophyllum majus, fig.
113, C) they are forked like the foliage-leaves and bear a close resemblance
to the abnormal sporophylls of Tmesipteris. Moreover, in
Sphenophyllostachys Römeri (fig. 113, A) each ventral lobe of a sporophyll
bears two sporangia, a condition almost identical with that represented by
the occasional occurrence of a synangium on a comparatively long stalk in
Tmesipteris. Similarly the more elaborate sporophylls of Cheirostrobus may
be compared with the branched sporophylls of Tmesipteris (fig. 120). This
agreement between the sporophylls of the Palaeozoic and recent genera
acquires additional importance from the very close resemblance between
the exarch stele of Sphenophyllum and that of the genus Psilotum, which
conforms to the Palaeozoic type not only in the centripetal character of the
primary xylem and in its exarch structure, but also in the occasional
occurrence of secondary xylem[31], and in the stellate form of its transverse
section. The occasional mesarch structure of the stele of Cheirostrobus
finds a parallel in the mesarch xylem groups in the stem of Tmesipteris. It is
thus on the strength of these resemblances that Thomas and Bower would
remove the Psilotaceae from the group Lycopodiales and unite them with
Sphenophyllum and Cheirostrobus in the Sphenophyllales. While admitting
the validity of the comparison briefly referred to above, I prefer to retain the
Psilotaceae as a division of the Pteridophyta including only Psilotum and
Tmesipteris.
SPHENOPHYLLUM
In his recent book on The Origin of Land Flora, Prof. Bower raises
objection to the use of the term ventral lobe in speaking of the sporangium-
bearing stalk or sporangiophore borne on the sporophyll of Sphenophyllum.
He points out that the use of this term implies the derivation of the
sporangiophore by metamorphosis of part of a vegetative leaf, an opinion
untenable in the absence of proof. The designation sporangiophore is no
doubt preferable to that of ventral lobe as it carries with it no admission of
particular morphological value; as a further concession to a non-committal
attitude we may provisionally at least regard a sporangiophore as an organ
sui generis “and not the result of modification of any other part[32].”
either simple with dichotomously branched veins or the lamina is deeply
divided into two or more segments. In some types of Sphenophyllostachys
the bracts are simple (S. Dawsoni), but in others (Sphenophyllum majus, fig.
113, C) they are forked like the foliage-leaves and bear a close resemblance
to the abnormal sporophylls of Tmesipteris. Moreover, in
Sphenophyllostachys Römeri (fig. 113, A) each ventral lobe of a sporophyll
bears two sporangia, a condition almost identical with that represented by
the occasional occurrence of a synangium on a comparatively long stalk in
Tmesipteris. Similarly the more elaborate sporophylls of Cheirostrobus may
be compared with the branched sporophylls of Tmesipteris (fig. 120). This
agreement between the sporophylls of the Palaeozoic and recent genera
acquires additional importance from the very close resemblance between
the exarch stele of Sphenophyllum and that of the genus Psilotum, which
conforms to the Palaeozoic type not only in the centripetal character of the
primary xylem and in its exarch structure, but also in the occasional
occurrence of secondary xylem[31], and in the stellate form of its transverse
section. The occasional mesarch structure of the stele of Cheirostrobus
finds a parallel in the mesarch xylem groups in the stem of Tmesipteris. It is
thus on the strength of these resemblances that Thomas and Bower would
remove the Psilotaceae from the group Lycopodiales and unite them with
Sphenophyllum and Cheirostrobus in the Sphenophyllales. While admitting
the validity of the comparison briefly referred to above, I prefer to retain the
Psilotaceae as a division of the Pteridophyta including only Psilotum and
Tmesipteris.
SPHENOPHYLLUM
In his recent book on The Origin of Land Flora, Prof. Bower raises
objection to the use of the term ventral lobe in speaking of the sporangium-
bearing stalk or sporangiophore borne on the sporophyll of Sphenophyllum.
He points out that the use of this term implies the derivation of the
sporangiophore by metamorphosis of part of a vegetative leaf, an opinion
untenable in the absence of proof. The designation sporangiophore is no
doubt preferable to that of ventral lobe as it carries with it no admission of
particular morphological value; as a further concession to a non-committal
attitude we may provisionally at least regard a sporangiophore as an organ
sui generis “and not the result of modification of any other part[32].”
Page 46
The view put forward by Prof. Lignier[33] that the Sphenophyllales are
descendants of primitive ferns is not convincing, and his comparison of
Sphenophyllum with Archaeopteris lacks force in view of our ignorance as
to the nature of the reproductive organs of the latter genus. That the
Sphenophyllales are connected with the Equisetales and with the Psilotales
by important morphological features is clear; but the comparison between
the sporophylls of the extinct genera with those of the existing genus
Tmesipteris, though helpful and possibly based on true homology, cannot be
considered as settling the morphological value of the sporangiophores of
Sphenophyllum and Cheirostrobus.
I do not propose to discuss at length the different views in regard to the
morphological nature of the sporangiophore of Sphenophyllum. The
comparison, which we owe in the first instance to Scott, with the
synangium of the Psilotales with its short stalk, though not accepted by
Lignier as a comparison based on true homology, is one which appeals to
many botanists and is probably the best so far suggested. The further
question, whether these sporangiophores are to be called foliar or axial
structures is one which has been answered by several authors, but it is
improbable that we shall soon arrive at a decision likely to be accepted as
final. Discussions of this kind tend to assume an exaggerated importance
and frequently carry with them the implication that every appendage of the
nature of a sporangiophore can be labelled either shoot or leaf. We treat the
question from an academic standpoint and run a risk of ignoring the fact
that the conception of stem and leaf is based on morphological
characteristics, which have been evolved as the result of gradual
differentiation of parts of one originally homogeneous whole. There is
much that is attractive in the view recently propounded by Mr Tansley that
a leaf is not an appendicular organ differing ab initio from the axis on
which it is borne, but that it is in phylogenetic origin a “branch-system of a
primitive undifferentiated sporangium-bearing thallus[34].” Admitting the
probability that this view is correct, our faith in the importance of
discussions on the morphological nature of sporangiophores is shaken, and
we realise the possibility that our zeal for formality and classification may
lead to results inconsistent with an evolutionary standpoint[35].
descendants of primitive ferns is not convincing, and his comparison of
Sphenophyllum with Archaeopteris lacks force in view of our ignorance as
to the nature of the reproductive organs of the latter genus. That the
Sphenophyllales are connected with the Equisetales and with the Psilotales
by important morphological features is clear; but the comparison between
the sporophylls of the extinct genera with those of the existing genus
Tmesipteris, though helpful and possibly based on true homology, cannot be
considered as settling the morphological value of the sporangiophores of
Sphenophyllum and Cheirostrobus.
I do not propose to discuss at length the different views in regard to the
morphological nature of the sporangiophore of Sphenophyllum. The
comparison, which we owe in the first instance to Scott, with the
synangium of the Psilotales with its short stalk, though not accepted by
Lignier as a comparison based on true homology, is one which appeals to
many botanists and is probably the best so far suggested. The further
question, whether these sporangiophores are to be called foliar or axial
structures is one which has been answered by several authors, but it is
improbable that we shall soon arrive at a decision likely to be accepted as
final. Discussions of this kind tend to assume an exaggerated importance
and frequently carry with them the implication that every appendage of the
nature of a sporangiophore can be labelled either shoot or leaf. We treat the
question from an academic standpoint and run a risk of ignoring the fact
that the conception of stem and leaf is based on morphological
characteristics, which have been evolved as the result of gradual
differentiation of parts of one originally homogeneous whole. There is
much that is attractive in the view recently propounded by Mr Tansley that
a leaf is not an appendicular organ differing ab initio from the axis on
which it is borne, but that it is in phylogenetic origin a “branch-system of a
primitive undifferentiated sporangium-bearing thallus[34].” Admitting the
probability that this view is correct, our faith in the importance of
discussions on the morphological nature of sporangiophores is shaken, and
we realise the possibility that our zeal for formality and classification may
lead to results inconsistent with an evolutionary standpoint[35].
Page 47
Page 48
CHAPTER XIII.
PSILOTALES.
The two recent genera Psilotum and Tmesipteris are usually spoken of as
members of the family Psilotaceae which is included as one of the
subdivisions of the Lycopodiales. It is probable, as Scott[36] first suggested,
that these two plants are more nearly allied than are any other existing types
to the Palaeozoic genus Sphenophyllum.
We may give expression to the undoubted resemblances between
Tmesipteris and Psilotum and the Sphenophyllales by including the recent
genera as members of that group, originally founded on the extinct genus
Sphenophyllum; this is the course adopted by Thomas[37] and by Bower[38]:
or we may emphasise the fact that these two recent genera differ in certain
important respects from Lycopodium and Selaginella by removing them to a
separate group, the Psilotales. The latter course is preferred on the ground
that the inclusion of Psilotum and Tmesipteris in a group founded on an
extinct and necessarily imperfectly known type, is based on insufficient
evidence and carries with it an assumption of closer relationship than has
been satisfactorily established.
The genus Tmesipteris (fig. 120, A) is represented by a single species T.
tannensis Bertr.[39] which usually occurs as an epiphyte on the stems of tree-
ferns in Australia, New Zealand, and Polynesia. Psilotum, with two species
P. triquetrum Sw. (fig. 118) and P. complanatum Sw., flourishes in moist
tropical regions of both hemispheres, growing either on soil rich in organic
substances or as an epiphyte. Both genera are considered to be more or less
saprophytic.
PSILOTALES.
The two recent genera Psilotum and Tmesipteris are usually spoken of as
members of the family Psilotaceae which is included as one of the
subdivisions of the Lycopodiales. It is probable, as Scott[36] first suggested,
that these two plants are more nearly allied than are any other existing types
to the Palaeozoic genus Sphenophyllum.
We may give expression to the undoubted resemblances between
Tmesipteris and Psilotum and the Sphenophyllales by including the recent
genera as members of that group, originally founded on the extinct genus
Sphenophyllum; this is the course adopted by Thomas[37] and by Bower[38]:
or we may emphasise the fact that these two recent genera differ in certain
important respects from Lycopodium and Selaginella by removing them to a
separate group, the Psilotales. The latter course is preferred on the ground
that the inclusion of Psilotum and Tmesipteris in a group founded on an
extinct and necessarily imperfectly known type, is based on insufficient
evidence and carries with it an assumption of closer relationship than has
been satisfactorily established.
The genus Tmesipteris (fig. 120, A) is represented by a single species T.
tannensis Bertr.[39] which usually occurs as an epiphyte on the stems of tree-
ferns in Australia, New Zealand, and Polynesia. Psilotum, with two species
P. triquetrum Sw. (fig. 118) and P. complanatum Sw., flourishes in moist
tropical regions of both hemispheres, growing either on soil rich in organic
substances or as an epiphyte. Both genera are considered to be more or less
saprophytic.
Page 49
Fig. 118. Psilotum triquetrum (½ natural size).
A. Synangium.
B. Sporophyll after removal of the synangium. (M.S.)
Psilotum. The common tropical species P. triquetrum (fig. 118) is
characterised by an underground rhizome which forms a confused mass of
dark brown branches covered with filamentous hairs as substitutes for roots
and gives off erect repeatedly forked aerial shoots. In P. complanatum[40] the
habit is similar to that of the more abundant and better-known species, but
the pendulous shoots are characterised by their broader and flatter form. In
both species the function of carbon-assimilation is performed by the outer
A. Synangium.
B. Sporophyll after removal of the synangium. (M.S.)
Psilotum. The common tropical species P. triquetrum (fig. 118) is
characterised by an underground rhizome which forms a confused mass of
dark brown branches covered with filamentous hairs as substitutes for roots
and gives off erect repeatedly forked aerial shoots. In P. complanatum[40] the
habit is similar to that of the more abundant and better-known species, but
the pendulous shoots are characterised by their broader and flatter form. In
both species the function of carbon-assimilation is performed by the outer
Page 50
cortex of the green branches, as the small size of the widely-separated
foliage leaves renders them practically useless as assimilating organs.
The sporophylls consist of a short axis terminating in two small divergent
forks and bearing on its adaxial surface a trilocular or in rare cases a
bilocular synangium (fig. 118, A and B). The walls of the loculi are
composed of several layers of cells and dehiscence takes place along three
lines radiating from the centre of the synangium. Professor Thomas[41] has
recorded “fairly numerous instances in Psilotum of a second dichotomy of
one branch of the first fork, or, less frequently, of both branches”: instead of
one synangium subtended by the two slender leaflets of the forked
sporophyll-axis, there may be two synangia and three leaf-lobes or three
synangia and four leaf-lobes. The occurrence of both these abnormalities in
Psilotum and Tmesipteris shows a decided tendency in the Psilotales to a
repeated dichotomy of the sporophylls[42].
A single stele[43] with a fluted surface occupies the axis of an aerial shoot
(fig. 119, A); the axial region is occupied by a core of elongated mechanical
elements (s), which may occasionally extend to the periphery of the xylem
and break the continuity of the band of scalariform tracheae (fig. 119, A, a).
The tracheae form the arms of an irregularly stellate stele and each arm is
terminated by protoxylem elements (fig. 119, B, px). The rays of the xylem
cylinder, which may be as many as six or eight in the upper part of the
aerial shoots, become reduced in number as the rhizome is approached,
assuming a diarch structure near the junction. In the rhizome the xylem
forms an approximately triangular group of tracheae without any core of
mechanical elements. Three to four layers of parenchyma succeeded
externally by an ill-defined phloem (fig. 119, A, p) surround the xylem and
a fairly distinct endodermis (fig. 119, A and B, e) encloses the whole. To Mr
Boodle[44] is due the interesting discovery that in some parts of the rhizome
the parenchymatous zone surrounding the scalariform tracheae may become
the seat of meristematic activity which results in the production of
secondary tracheae often characterised by a sinuous longitudinal course.
There is no definite cambium, but the radially disposed tracheae and the
adjacent parenchymatous elements clearly demonstrate the secondary
nature of the tissue immediately external to the group of primary xylem.
Fig. 119, C, drawn from a section kindly supplied by Mr Boodle, shows the
secondary xylem elements at x2 associated with radially disposed thin-
foliage leaves renders them practically useless as assimilating organs.
The sporophylls consist of a short axis terminating in two small divergent
forks and bearing on its adaxial surface a trilocular or in rare cases a
bilocular synangium (fig. 118, A and B). The walls of the loculi are
composed of several layers of cells and dehiscence takes place along three
lines radiating from the centre of the synangium. Professor Thomas[41] has
recorded “fairly numerous instances in Psilotum of a second dichotomy of
one branch of the first fork, or, less frequently, of both branches”: instead of
one synangium subtended by the two slender leaflets of the forked
sporophyll-axis, there may be two synangia and three leaf-lobes or three
synangia and four leaf-lobes. The occurrence of both these abnormalities in
Psilotum and Tmesipteris shows a decided tendency in the Psilotales to a
repeated dichotomy of the sporophylls[42].
A single stele[43] with a fluted surface occupies the axis of an aerial shoot
(fig. 119, A); the axial region is occupied by a core of elongated mechanical
elements (s), which may occasionally extend to the periphery of the xylem
and break the continuity of the band of scalariform tracheae (fig. 119, A, a).
The tracheae form the arms of an irregularly stellate stele and each arm is
terminated by protoxylem elements (fig. 119, B, px). The rays of the xylem
cylinder, which may be as many as six or eight in the upper part of the
aerial shoots, become reduced in number as the rhizome is approached,
assuming a diarch structure near the junction. In the rhizome the xylem
forms an approximately triangular group of tracheae without any core of
mechanical elements. Three to four layers of parenchyma succeeded
externally by an ill-defined phloem (fig. 119, A, p) surround the xylem and
a fairly distinct endodermis (fig. 119, A and B, e) encloses the whole. To Mr
Boodle[44] is due the interesting discovery that in some parts of the rhizome
the parenchymatous zone surrounding the scalariform tracheae may become
the seat of meristematic activity which results in the production of
secondary tracheae often characterised by a sinuous longitudinal course.
There is no definite cambium, but the radially disposed tracheae and the
adjacent parenchymatous elements clearly demonstrate the secondary
nature of the tissue immediately external to the group of primary xylem.
Fig. 119, C, drawn from a section kindly supplied by Mr Boodle, shows the
secondary xylem elements at x2 associated with radially disposed thin-
Page 51
walled cells abutting on the primary xylem, x1. It is probable that this added
tissue may be a remnant of a more extensive secondary thickening
characteristic of the ancestors of the recent species. In their manner of
occurrence and sinuous course these secondary tracheids bear a
resemblance to the secondary xylem of Lepidodendron fuliginosum[45]. The
stele of the aerial shoot bears a fairly close resemblance to the vascular axis
of Cheirostrobus, and its three-rayed form in the lower portions of the green
branches recalls that of the Sphenophyllum stele, except that the axial xylem
elements of the Palaeozoic genus are usually represented in Psilotum by
mechanical tissue. The cortex consists of three regions (fig. 119, A), an
outer zone of chlorophyllous tissue (a) rich in intercellular spaces
succeeded by a band of mechanical tissue (b) which gradually passes into
an inner region of larger and thinner-walled cells (c).
tissue may be a remnant of a more extensive secondary thickening
characteristic of the ancestors of the recent species. In their manner of
occurrence and sinuous course these secondary tracheids bear a
resemblance to the secondary xylem of Lepidodendron fuliginosum[45]. The
stele of the aerial shoot bears a fairly close resemblance to the vascular axis
of Cheirostrobus, and its three-rayed form in the lower portions of the green
branches recalls that of the Sphenophyllum stele, except that the axial xylem
elements of the Palaeozoic genus are usually represented in Psilotum by
mechanical tissue. The cortex consists of three regions (fig. 119, A), an
outer zone of chlorophyllous tissue (a) rich in intercellular spaces
succeeded by a band of mechanical tissue (b) which gradually passes into
an inner region of larger and thinner-walled cells (c).
Page 52
Fig. 119.
A. Diagram of transverse section of aerial shoot of Psilotum triquetrum. a—c, cortex;
p, phloem; e, endodermis; s, stereome; x, xylem; a, gap in xylem.
B. Enlarged view of one of the angles of the xylem shown in A. px, protoxylem.
C. Part of transverse section of an approximately triangular rhizome stele showing a
portion of the metaxylem x1; px, protoxylem elements; x2, secondary xylem.
TMESIPTERIS
The genus Tmesipteris[46] agrees with Psilotum in general habit and in its
epiphytic and probably in some degree saprophytic mode of life. Its brown
rootless rhizome, which grows among the roots of tree-ferns or rarely in the
A. Diagram of transverse section of aerial shoot of Psilotum triquetrum. a—c, cortex;
p, phloem; e, endodermis; s, stereome; x, xylem; a, gap in xylem.
B. Enlarged view of one of the angles of the xylem shown in A. px, protoxylem.
C. Part of transverse section of an approximately triangular rhizome stele showing a
portion of the metaxylem x1; px, protoxylem elements; x2, secondary xylem.
TMESIPTERIS
The genus Tmesipteris[46] agrees with Psilotum in general habit and in its
epiphytic and probably in some degree saprophytic mode of life. Its brown
rootless rhizome, which grows among the roots of tree-ferns or rarely in the
Page 53
ground, gives off pendulous or erect shoots reaching a length of two feet
and bearing lanceolate mucronate leaves 2–3 cm. long (fig. 120, A) attached
by decurrent leaf-bases. The sporophylls, replacing the upper leaves or
occurring in more or less well-defined zones alternating with the foliage
leaves, consist of a short axis terminating in a pair of lanceolate lobes and
bearing on its adaxial surface an elongated bilocular synangium attached to
a very short stalk (fig. 120, B). Reference has already been made to the
divergent opinions as to the morphological nature of the sporophylls or
sporangiophores, but recent investigations distinctly favour the view that a
sporophyll is best interpreted as a stalked leaf with two sterile laminae and
an almost sessile, or in some cases a more obviously stalked, synangium;
the whole sporophyll is characterised by the possession of a ventral and a
dorsal lobe[47]. The drawings reproduced in fig. 120, D and F, illustrate some
of the frequent variations described by Thomas in plants which he observed
in the New Zealand forests. The sporophyll shown in fig. 120, D and F, has
branched twice and bears three synangia.
and bearing lanceolate mucronate leaves 2–3 cm. long (fig. 120, A) attached
by decurrent leaf-bases. The sporophylls, replacing the upper leaves or
occurring in more or less well-defined zones alternating with the foliage
leaves, consist of a short axis terminating in a pair of lanceolate lobes and
bearing on its adaxial surface an elongated bilocular synangium attached to
a very short stalk (fig. 120, B). Reference has already been made to the
divergent opinions as to the morphological nature of the sporophylls or
sporangiophores, but recent investigations distinctly favour the view that a
sporophyll is best interpreted as a stalked leaf with two sterile laminae and
an almost sessile, or in some cases a more obviously stalked, synangium;
the whole sporophyll is characterised by the possession of a ventral and a
dorsal lobe[47]. The drawings reproduced in fig. 120, D and F, illustrate some
of the frequent variations described by Thomas in plants which he observed
in the New Zealand forests. The sporophyll shown in fig. 120, D and F, has
branched twice and bears three synangia.
Page 54
Fig. 120. Tmesipteris.
A. Foliage leaves.
B. Sporophyll and bilocular synangium.
C. Diagram of transverse section of stele. px, protoxylem.
D, F. Abnormal sporophylls. (From drawings made by Prof. Thomas and generously
placed at my disposal. A.C.S.)
E. Portion of C enlarged.
The aerial branches of Tmesipteris possess a central cylinder of separate
xylem groups in which the protoxylem occupies an internal position (fig.
120, C and E, px) enclosing an axial parenchymatous region. The cells of a
few layers of the inner cortex immediately outside the endodermis are
A. Foliage leaves.
B. Sporophyll and bilocular synangium.
C. Diagram of transverse section of stele. px, protoxylem.
D, F. Abnormal sporophylls. (From drawings made by Prof. Thomas and generously
placed at my disposal. A.C.S.)
E. Portion of C enlarged.
The aerial branches of Tmesipteris possess a central cylinder of separate
xylem groups in which the protoxylem occupies an internal position (fig.
120, C and E, px) enclosing an axial parenchymatous region. The cells of a
few layers of the inner cortex immediately outside the endodermis are
Page 55
rendered conspicuous by a dark brown deposit. The cortex as a whole is
composed of uniform parenchymatous tissue. In the lower part of the aerial
shoots and in the rhizome the xylem forms a solid strand without
protoxylem elements and conforms more clearly to that of Psilotum.
In this short account of the anatomy of Tmesipteris no mention is made
of the effect produced on the stele by the departure of leaf-traces and of
vascular stands to supply branches. Miss Sykes[48] in a recently published
paper on the genus has shown that the exit of a leaf-trace does not break the
continuity of the xylem of the stele, while the exit of a sporophyll-trace is
marked by an obvious gap. Evidence is adduced in support of the
conclusion that this difference, which at first sight appears to be one of
morphological importance, is in reality merely a question of degree and “is
due to the earlier preparation for the formation of ‘sporophyll’ than leaf-
traces.” Miss Sykes gives her adherence to the view that the “sporophylls”
of Tmesipteris are branches and not leaves, but despite the arguments
advanced this interpretation seems to me less probable than that which
recognises the sporophyll as a foliar organ. Prof. Lignier[49] has pointed out
that if Miss Sykes’s conclusion as to the axial nature of the sporophyll in
Tmesipteris is accepted, it diminishes the force of the comparison between
the sporophylls of that genus and Sphenophyllum as those of the latter can
hardly be regarded as other than foliar organs.
Both members of the Psilotales may, as Boodle has suggested, be
regarded as descendants of a common parent in which the aerial stems
possessed a fluted or stellate cylinder of mesarch xylem. There can be no
doubt as to the significance of the morphological resemblances between the
Psilotales and the genera Sphenophyllum and Cheirostrobus, but the
position of Tmesipteris and Psilotum in the plant-kingdom may probably be
best expressed by adopting the group-name Psilotales rather than by
transferring the recent genera to the Sphenophyllales. One of the most
striking differences between the Psilotales and the genus Lycopodium is in
the form of the sporophylls and sporangia; in Lycopodium a single
sporophyll bears a unilocular sporangium, but in the Psilotales the
sporophyll may be described as a bilobed structure homologous with a
foliage-leaf, bearing a sporangiophore which consists of a short stalk
terminating in a bilocular or trilocular synangium; the short stalk receives a
composed of uniform parenchymatous tissue. In the lower part of the aerial
shoots and in the rhizome the xylem forms a solid strand without
protoxylem elements and conforms more clearly to that of Psilotum.
In this short account of the anatomy of Tmesipteris no mention is made
of the effect produced on the stele by the departure of leaf-traces and of
vascular stands to supply branches. Miss Sykes[48] in a recently published
paper on the genus has shown that the exit of a leaf-trace does not break the
continuity of the xylem of the stele, while the exit of a sporophyll-trace is
marked by an obvious gap. Evidence is adduced in support of the
conclusion that this difference, which at first sight appears to be one of
morphological importance, is in reality merely a question of degree and “is
due to the earlier preparation for the formation of ‘sporophyll’ than leaf-
traces.” Miss Sykes gives her adherence to the view that the “sporophylls”
of Tmesipteris are branches and not leaves, but despite the arguments
advanced this interpretation seems to me less probable than that which
recognises the sporophyll as a foliar organ. Prof. Lignier[49] has pointed out
that if Miss Sykes’s conclusion as to the axial nature of the sporophyll in
Tmesipteris is accepted, it diminishes the force of the comparison between
the sporophylls of that genus and Sphenophyllum as those of the latter can
hardly be regarded as other than foliar organs.
Both members of the Psilotales may, as Boodle has suggested, be
regarded as descendants of a common parent in which the aerial stems
possessed a fluted or stellate cylinder of mesarch xylem. There can be no
doubt as to the significance of the morphological resemblances between the
Psilotales and the genera Sphenophyllum and Cheirostrobus, but the
position of Tmesipteris and Psilotum in the plant-kingdom may probably be
best expressed by adopting the group-name Psilotales rather than by
transferring the recent genera to the Sphenophyllales. One of the most
striking differences between the Psilotales and the genus Lycopodium is in
the form of the sporophylls and sporangia; in Lycopodium a single
sporophyll bears a unilocular sporangium, but in the Psilotales the
sporophyll may be described as a bilobed structure homologous with a
foliage-leaf, bearing a sporangiophore which consists of a short stalk
terminating in a bilocular or trilocular synangium; the short stalk receives a
Page 56
special branch from the vascular bundle of the sterile portion of the
sporophyll[50].
Fossils described by authors as being closely allied to Psilotum.
A search through palaeobotanical literature reveals the existence of a
very small number of specimens which have been identified as
representatives of the Psilotales. An inspection of the material or published
drawings leads one to the conclusion that practically no information of a
satisfactory kind is available in regard to the past history of the two
southern genera Psilotum and Tmesipteris, which are regarded by some
botanists as relics of an ancient branch[51] of pteridophytes.
PSILOTITES, ETC.
In 1842 Münster[52] instituted the genus Psilotites for a small impression
of a slender branched axis from Jurassic rocks near Mannheim in Germany
which he named Psilotites filiformis; Schimper[53] spoke of the specimens as
too doubtful for determination, an opinion with which every botanist would
cordially agree. Goldenberg’s species Psilotites lithanthracis[54] from the
Saarbrücken coal-field is founded on impressions of axes: some of these are
dichotomously branched and bear small oval projections, which may be
rudimentary leaves or possibly leaf-scars. More recently Kidston[55]
described specimens of branched axes from the Lanarkshire coal-field
bearing a row of lateral thorn-like projections under the title Psilotites
unilateralis; but these fragments, as Dr Kidston himself admits, are of no
botanical value.
In a paper on fossil Salvinias, Hollick[56] mentions Salvinia reticulata,
originally described by Heer and by Ettingshausen and S. Alleni Lesq.[57] a
Tertiary species, and calls attention to their very close resemblance in form,
nervation, and apex to the leaves of the genus Tmesipteris: he refers both
species to that genus. The drawings reproduced by Hollick represent leaves
with a midrib and numerous anastomosing lateral veins, whereas in
Tmesipteris the lamina of the leaf has a midrib without lateral branches. An
enlarged drawing of the outlines of the epidermal cells would correspond
closely with the small reticulations in the fossil leaves and it may be that
there has been some confusion between veins and cell-outlines. In any case
there would seem to be no reason for the use of the recent generic name[58].
sporophyll[50].
Fossils described by authors as being closely allied to Psilotum.
A search through palaeobotanical literature reveals the existence of a
very small number of specimens which have been identified as
representatives of the Psilotales. An inspection of the material or published
drawings leads one to the conclusion that practically no information of a
satisfactory kind is available in regard to the past history of the two
southern genera Psilotum and Tmesipteris, which are regarded by some
botanists as relics of an ancient branch[51] of pteridophytes.
PSILOTITES, ETC.
In 1842 Münster[52] instituted the genus Psilotites for a small impression
of a slender branched axis from Jurassic rocks near Mannheim in Germany
which he named Psilotites filiformis; Schimper[53] spoke of the specimens as
too doubtful for determination, an opinion with which every botanist would
cordially agree. Goldenberg’s species Psilotites lithanthracis[54] from the
Saarbrücken coal-field is founded on impressions of axes: some of these are
dichotomously branched and bear small oval projections, which may be
rudimentary leaves or possibly leaf-scars. More recently Kidston[55]
described specimens of branched axes from the Lanarkshire coal-field
bearing a row of lateral thorn-like projections under the title Psilotites
unilateralis; but these fragments, as Dr Kidston himself admits, are of no
botanical value.
In a paper on fossil Salvinias, Hollick[56] mentions Salvinia reticulata,
originally described by Heer and by Ettingshausen and S. Alleni Lesq.[57] a
Tertiary species, and calls attention to their very close resemblance in form,
nervation, and apex to the leaves of the genus Tmesipteris: he refers both
species to that genus. The drawings reproduced by Hollick represent leaves
with a midrib and numerous anastomosing lateral veins, whereas in
Tmesipteris the lamina of the leaf has a midrib without lateral branches. An
enlarged drawing of the outlines of the epidermal cells would correspond
closely with the small reticulations in the fossil leaves and it may be that
there has been some confusion between veins and cell-outlines. In any case
there would seem to be no reason for the use of the recent generic name[58].
Page 57
Among other fossils assigned to the Psilotales we have Marion’s genus
Gomphostrobus from the Permian of France and Germany[59]. Marion
placed this plant in the Coniferales on the strength of its resemblance to
Walchia and Araucaria, but Potonié[60] is inclined to recognise in the leaves
and monospermic sporophylls characters suggestive of Lycopodiaceous
affinity.
The latter author in 1891[61], in ignorance of Marion’s proposal to adopt
the name Gomphostrobus, instituted a genus Psilotiphyllum for the
sporophylls of a species originally described by Geinitz[62] as
Sigillariostrobus bifidus, but he subsequently adopted Marion’s designation
and with some hesitation included the French and German specimens in the
Psilotales. As stated elsewhere[63], Potonié’s arguments in favour of his view
hardly carry conviction, and it is probably more in accordance with truth to
deal with Gomphostrobus in the chapter devoted to the Coniferales.
Psilophyton.
The generic title Psilophyton, instituted by the late Sir William
Dawson[64], has become familiar to geologists as that of a Pre-Carboniferous
plant characteristic of Devonian and Silurian rocks in Canada, the United
States of America, and Europe. From the botanist’s point of view the name
stands for miscellaneous remains of plants of different types and in many
cases unworthy of record. The genus was founded on impressions of
branched axes from the Devonian strata of New Brunswick resembling the
rachis and portions of lateral pinnae of ferns or the forked slender twigs of a
Lycopod. The type-species Psilophyton princeps Daws. as represented on
somewhat slender evidence in Dawson’s restoration, which accompanies
the original description of the genus and has since been copied by several
authors, is characterised by the possession of a horizontal rhizome bearing
numerous rootlets and giving off dichotomously branched aerial shoots with
spinous appendages, compared with rudimentary leaves, and terminating in
slender branchlets bearing pendulous oval “spore-cases” from their tips.
Some of the branchlets exhibit a fern-like vernation. The plant is spoken of
by Dawson as apparently a generalised type[65], resembling in habit and in
its rudimentary leaves the recent genus Psilotum and presenting points of
contact with ferns. Specimens were found in an imperfectly petrified state
Gomphostrobus from the Permian of France and Germany[59]. Marion
placed this plant in the Coniferales on the strength of its resemblance to
Walchia and Araucaria, but Potonié[60] is inclined to recognise in the leaves
and monospermic sporophylls characters suggestive of Lycopodiaceous
affinity.
The latter author in 1891[61], in ignorance of Marion’s proposal to adopt
the name Gomphostrobus, instituted a genus Psilotiphyllum for the
sporophylls of a species originally described by Geinitz[62] as
Sigillariostrobus bifidus, but he subsequently adopted Marion’s designation
and with some hesitation included the French and German specimens in the
Psilotales. As stated elsewhere[63], Potonié’s arguments in favour of his view
hardly carry conviction, and it is probably more in accordance with truth to
deal with Gomphostrobus in the chapter devoted to the Coniferales.
Psilophyton.
The generic title Psilophyton, instituted by the late Sir William
Dawson[64], has become familiar to geologists as that of a Pre-Carboniferous
plant characteristic of Devonian and Silurian rocks in Canada, the United
States of America, and Europe. From the botanist’s point of view the name
stands for miscellaneous remains of plants of different types and in many
cases unworthy of record. The genus was founded on impressions of
branched axes from the Devonian strata of New Brunswick resembling the
rachis and portions of lateral pinnae of ferns or the forked slender twigs of a
Lycopod. The type-species Psilophyton princeps Daws. as represented on
somewhat slender evidence in Dawson’s restoration, which accompanies
the original description of the genus and has since been copied by several
authors, is characterised by the possession of a horizontal rhizome bearing
numerous rootlets and giving off dichotomously branched aerial shoots with
spinous appendages, compared with rudimentary leaves, and terminating in
slender branchlets bearing pendulous oval “spore-cases” from their tips.
Some of the branchlets exhibit a fern-like vernation. The plant is spoken of
by Dawson as apparently a generalised type[65], resembling in habit and in
its rudimentary leaves the recent genus Psilotum and presenting points of
contact with ferns. Specimens were found in an imperfectly petrified state
Page 58
showing a central cylinder of scalariform tracheae surrounded by a broad
cortical zone of parenchyma and fibrous tissue.
Among other species described by the author of the genus we need only
mention Psilophyton robustius, characterised by vegetative shoots and
“spore-cases” similar to those of the type-species; but, as Solms-Laubach[66]
has pointed out, the petrified sections referred by Dawson to P. robustius
are of an entirely different anatomical type from that of P. princeps[67].
British fossils from the Old Red Sandstone from the north of Scotland,
Orkney and Caithness, originally figured by Hugh Miller and compared by
him with algae but more especially with recent Lycopods, were
subsequently placed by Carruthers[68] in the genus Psilophyton as P.
Dechianum, the specific designation being chosen on the ground that the
Scotch specimens are specifically identical with fossils described by
Goeppert[69] as Haliserites Dechianus.
Various opinions have been expressed in regard to the nature of the
Devonian species Haliserites Dechianus Goepp. with which Carruthers[70]
identified Miller’s Old Red Sandstone plant: reference may be made to a
paper by White[71] containing figures of dichotomously branched
impressions described as species of Thamnocladus which he includes
among the algae.
In describing some Belgian impressions of Devonian age as
Lepidodendron gaspianum Daws. Crépin[72] states that Carruthers has come
to regard the specimens named by him Psilophyton Dechianum as branches
of a Lepidodendron; he also quotes Carruthers as having expressed the
opinion that the name Psilophyton had been employed by Dawson for two
kinds of fossils, some being twigs of Lepidodendron while others, identified
by Dawson as the reproductive branches of species of Psilophyton,
represent the spore-cases of ferns comparable with Stur’s genus Rhodea[73].
One of the examples figured by Carruthers[74] as P. Dechianum from Thurso
(preserved in the British Museum, no. 52636), measuring 34 cm. in length
and 8 mm. broad, bears a close resemblance to a fern rhizome covered with
ramental scales such as that of a species of Davallia. Other Belgian
specimens described by Gilkinet[75] as Lepidodendron burnotense, like
Crépin’s species, are no doubt generically identical with some of the Scotch
and Canadian fossils placed in the genus Psilophyton, though Penhallow[76]
cortical zone of parenchyma and fibrous tissue.
Among other species described by the author of the genus we need only
mention Psilophyton robustius, characterised by vegetative shoots and
“spore-cases” similar to those of the type-species; but, as Solms-Laubach[66]
has pointed out, the petrified sections referred by Dawson to P. robustius
are of an entirely different anatomical type from that of P. princeps[67].
British fossils from the Old Red Sandstone from the north of Scotland,
Orkney and Caithness, originally figured by Hugh Miller and compared by
him with algae but more especially with recent Lycopods, were
subsequently placed by Carruthers[68] in the genus Psilophyton as P.
Dechianum, the specific designation being chosen on the ground that the
Scotch specimens are specifically identical with fossils described by
Goeppert[69] as Haliserites Dechianus.
Various opinions have been expressed in regard to the nature of the
Devonian species Haliserites Dechianus Goepp. with which Carruthers[70]
identified Miller’s Old Red Sandstone plant: reference may be made to a
paper by White[71] containing figures of dichotomously branched
impressions described as species of Thamnocladus which he includes
among the algae.
In describing some Belgian impressions of Devonian age as
Lepidodendron gaspianum Daws. Crépin[72] states that Carruthers has come
to regard the specimens named by him Psilophyton Dechianum as branches
of a Lepidodendron; he also quotes Carruthers as having expressed the
opinion that the name Psilophyton had been employed by Dawson for two
kinds of fossils, some being twigs of Lepidodendron while others, identified
by Dawson as the reproductive branches of species of Psilophyton,
represent the spore-cases of ferns comparable with Stur’s genus Rhodea[73].
One of the examples figured by Carruthers[74] as P. Dechianum from Thurso
(preserved in the British Museum, no. 52636), measuring 34 cm. in length
and 8 mm. broad, bears a close resemblance to a fern rhizome covered with
ramental scales such as that of a species of Davallia. Other Belgian
specimens described by Gilkinet[75] as Lepidodendron burnotense, like
Crépin’s species, are no doubt generically identical with some of the Scotch
and Canadian fossils placed in the genus Psilophyton, though Penhallow[76]
Page 59
considers that the species Lycopodites Milleri is more correctly referred to
Lycopodites than to Psilophyton.
A more recent paper on the Geology of the Perry basin in South-eastern
Maine by Smith and White[77] contains a critical summary of the literature
on Psilophyton and drawings of specimens. The latter afford good examples
of Pre-Carboniferous plant fragments, such as are often met with in various
parts of the world, which conform in habit to the New Brunswick
specimens made by Dawson the type of his genus.
An examination of material in the Montreal Museum and of Hugh
Miller’s specimens in the Edinburgh collection leads me to share the
opinion of Count Solms-Laubach that the name Psilophyton has been
applied to plants which should not be included under one generic title. As
Kidston[78] pointed out, the Canadian species Psilophyton robustius is not
generically distinct from British and Belgian specimens referred to
Lepidodendron; it may possibly be identical with the Bohemian plants on
which Stur founded his genus Hostinella[79]. The Devonian plants described
by Stur have since been examined by Jahn[80] who regards them as vascular
plants, and not as algae to which Stur referred them; he mentions two
species of Psilophyton but gives no figures.
The “spore-cases” of Dawson may be found to be the microsporangia or
perhaps the small seeds of some pteridosperm; the forked axes with a
smooth surface and others figured by Miller and by Dawson, with the
surface covered with scales suggesting the ramenta of a fern, may be the
rachises or rhizomes of filicinean plants. Other specimens may be
Lepidodendron twigs, as for example the petrified fragments figured by
Dawson as Psilophyton princeps; while the stem identified as P. robustius is
most probably that of a Gymnosperm. It is doubtful whether a useful
purpose is served by retaining the genus Psilophyton. It was in the first
instance instituted on the assumption, which cannot be upheld, that the
abundant material in the New Brunswick beds bore a sufficiently close
resemblance to the rhizome and aerial branches of Psilotum. Psilophyton
has served as a name for miscellaneous plant fragments, many of which are
indeterminable. Dr White concludes his account of the genus with the
following words[81]:
Lycopodites than to Psilophyton.
A more recent paper on the Geology of the Perry basin in South-eastern
Maine by Smith and White[77] contains a critical summary of the literature
on Psilophyton and drawings of specimens. The latter afford good examples
of Pre-Carboniferous plant fragments, such as are often met with in various
parts of the world, which conform in habit to the New Brunswick
specimens made by Dawson the type of his genus.
An examination of material in the Montreal Museum and of Hugh
Miller’s specimens in the Edinburgh collection leads me to share the
opinion of Count Solms-Laubach that the name Psilophyton has been
applied to plants which should not be included under one generic title. As
Kidston[78] pointed out, the Canadian species Psilophyton robustius is not
generically distinct from British and Belgian specimens referred to
Lepidodendron; it may possibly be identical with the Bohemian plants on
which Stur founded his genus Hostinella[79]. The Devonian plants described
by Stur have since been examined by Jahn[80] who regards them as vascular
plants, and not as algae to which Stur referred them; he mentions two
species of Psilophyton but gives no figures.
The “spore-cases” of Dawson may be found to be the microsporangia or
perhaps the small seeds of some pteridosperm; the forked axes with a
smooth surface and others figured by Miller and by Dawson, with the
surface covered with scales suggesting the ramenta of a fern, may be the
rachises or rhizomes of filicinean plants. Other specimens may be
Lepidodendron twigs, as for example the petrified fragments figured by
Dawson as Psilophyton princeps; while the stem identified as P. robustius is
most probably that of a Gymnosperm. It is doubtful whether a useful
purpose is served by retaining the genus Psilophyton. It was in the first
instance instituted on the assumption, which cannot be upheld, that the
abundant material in the New Brunswick beds bore a sufficiently close
resemblance to the rhizome and aerial branches of Psilotum. Psilophyton
has served as a name for miscellaneous plant fragments, many of which are
indeterminable. Dr White concludes his account of the genus with the
following words[81]:
Page 60
“The examination of such so-called Psilophyton material as I have seen
shows the existence in America of two or more groups, represented by
several fairly well-marked species which possess stratigraphical value, and
which should be carefully diagnosed and illustrated. It is probable also that
additional material throwing light on the structure and relationships of these
very remarkable early types of land-plants will be discovered at some
locality. The inspection of the material in hand emphasises the need, as was
pointed out by Solms-Laubach, for the revision of the material referred by
various authors to Psilophyton, together with a thorough re-examination
and re-publication of the types.”
Until a thorough re-examination has been made of the Canadian material,
with a view to determine whether there exist substantial reasons for the
retention of Dawson’s genus, it is undesirable to continue to make use of
this name for Pre-Carboniferous fossils which are too incomplete to be
assigned with certainty to a definite group of plants. Dr White draws
attention to the similarity of some of the Perry basin specimens to
Nathorst’s genus Cephalotheca[82] from Devonian rocks of Bear Island in
the Arctic regions, a comparison which might be extended to other genera
and which serves to illustrate the possibility that many of the specimens
labelled Psilophyton may eventually be recognised as examples of well
defined generic types belonging to more than one group of plants.
shows the existence in America of two or more groups, represented by
several fairly well-marked species which possess stratigraphical value, and
which should be carefully diagnosed and illustrated. It is probable also that
additional material throwing light on the structure and relationships of these
very remarkable early types of land-plants will be discovered at some
locality. The inspection of the material in hand emphasises the need, as was
pointed out by Solms-Laubach, for the revision of the material referred by
various authors to Psilophyton, together with a thorough re-examination
and re-publication of the types.”
Until a thorough re-examination has been made of the Canadian material,
with a view to determine whether there exist substantial reasons for the
retention of Dawson’s genus, it is undesirable to continue to make use of
this name for Pre-Carboniferous fossils which are too incomplete to be
assigned with certainty to a definite group of plants. Dr White draws
attention to the similarity of some of the Perry basin specimens to
Nathorst’s genus Cephalotheca[82] from Devonian rocks of Bear Island in
the Arctic regions, a comparison which might be extended to other genera
and which serves to illustrate the possibility that many of the specimens
labelled Psilophyton may eventually be recognised as examples of well
defined generic types belonging to more than one group of plants.
Page 61
Page 62
CHAPTER XIV.
LYCOPODIALES.
The recent members of the Lycopodiales are considered apart from the
extinct genera in order that our examination of the latter may be facilitated
by a knowledge of the salient characteristics of the surviving types of this
important section of the Pteridophyta. A general acquaintance with the
extinct as well as with the recent genera will enable us to appreciate the
contrasts between the living and the fossil forms and to realise the
prominent position occupied by this group in the Palaeozoic period, a
position in striking contrast to the part played by the diminutive survivors in
the vegetation of the present day. In the account of the recent genera special
attention is drawn to such features as afford a clue to the interpretation of
the fossils, and the point of view adopted, which at times may appear to
lead to an excessive attention to details, is necessarily somewhat different
from that represented in botanical text-books[83].
A. HOMOSPOREAE.
Lycopodiaceae: genera Phylloglossum, Lycopodium.
B. HETEROSPOREAE.
Selaginellaceae: genus Selaginella.
Isoetaceae: genus Isoetes.
The existing plants included in the Lycopodiales are in nearly all cases
perennial herbaceous pteridophytes, exhibiting in their life-histories a well
marked alternation of generations. The sporophyte (asexual generation) is
characterised by the relatively small size of the leaves except in the genus
Isoetes (fig. 132) and in the Australian and New Zealand genus
Phylloglossum. The stems are usually erect or trailing, pendulous in
epiphytic species or small and tuberous in Isoetes and Phylloglossum. The
repeated forking of the shoots (monopodial and dichotomous branching) is
LYCOPODIALES.
The recent members of the Lycopodiales are considered apart from the
extinct genera in order that our examination of the latter may be facilitated
by a knowledge of the salient characteristics of the surviving types of this
important section of the Pteridophyta. A general acquaintance with the
extinct as well as with the recent genera will enable us to appreciate the
contrasts between the living and the fossil forms and to realise the
prominent position occupied by this group in the Palaeozoic period, a
position in striking contrast to the part played by the diminutive survivors in
the vegetation of the present day. In the account of the recent genera special
attention is drawn to such features as afford a clue to the interpretation of
the fossils, and the point of view adopted, which at times may appear to
lead to an excessive attention to details, is necessarily somewhat different
from that represented in botanical text-books[83].
A. HOMOSPOREAE.
Lycopodiaceae: genera Phylloglossum, Lycopodium.
B. HETEROSPOREAE.
Selaginellaceae: genus Selaginella.
Isoetaceae: genus Isoetes.
The existing plants included in the Lycopodiales are in nearly all cases
perennial herbaceous pteridophytes, exhibiting in their life-histories a well
marked alternation of generations. The sporophyte (asexual generation) is
characterised by the relatively small size of the leaves except in the genus
Isoetes (fig. 132) and in the Australian and New Zealand genus
Phylloglossum. The stems are usually erect or trailing, pendulous in
epiphytic species or small and tuberous in Isoetes and Phylloglossum. The
repeated forking of the shoots (monopodial and dichotomous branching) is
Page 63
a prominent feature of the group. The vascular tissue of the stem usually
assumes the form of a single axial strand (stele) (fig. 125), but the shoots of
some species of Selaginella often contain two or more distinct steles (fig.
131). The group as a whole is characterised by the centripetal development
of the xylem composed almost entirely of scalariform tracheids: secondary
xylem and phloem of a peculiar type occur in Isoetes, and the production of
secondary xylem elements in a very slight degree has been noticed in one
species of Selaginella (S. spinosa)[84]. The roots are constructed on a simple
plan, having in most cases only one strand of spiral protoxylem elements
(monarch structure). In Lycopodium, in which stem and root anatomy are
more nearly of the same type than in the majority of plants, several
protoxylem strands may be present. The sporangia are axillary or, more
frequently, borne on the upper surface of sporophylls, which are either
identical with or more or less distinct from the foliage leaves; in the latter
case the sporophylls often occur in the form of a well defined strobilus
(cone) at the tips of branches.
The gametophyte (sexual generation) is represented by prothalli which,
in the homosporous genera, may live underground as saprophytes, or the
upper portion may develop chlorophyll and project above the surface of the
ground as an irregularly lobed green structure (e.g. Lycopodium cernuum)
[85]
. In the heterosporous forms the prothalli are much reduced and do not
lead an independent existence outside the spore by the membrane of which
they are always more or less enclosed. The sexual organs are represented by
antheridia and archegonia; the male cells are provided with two cilia except
in Isoetes which has multiciliate antherozoids like those of the ferns.
The existing Lycopods, though widely distributed, never grow in
sufficiently dense masses to the exclusion of other plants to form a
conspicuous feature in the vegetation of a country. The inconspicuous rôle
which they play among the plant-associations of the present era affords a
striking contrast to the abundance of the arborescent species in the
Palaeozoic forests of the northern hemisphere.
• • • • •
Lycopodiaceae. Lycopodium, represented by nearly 100 species, forms a
constituent of most floras: epiphytic species predominate in tropical
regions, while others flourish on the mountains and moorlands of Britain
assumes the form of a single axial strand (stele) (fig. 125), but the shoots of
some species of Selaginella often contain two or more distinct steles (fig.
131). The group as a whole is characterised by the centripetal development
of the xylem composed almost entirely of scalariform tracheids: secondary
xylem and phloem of a peculiar type occur in Isoetes, and the production of
secondary xylem elements in a very slight degree has been noticed in one
species of Selaginella (S. spinosa)[84]. The roots are constructed on a simple
plan, having in most cases only one strand of spiral protoxylem elements
(monarch structure). In Lycopodium, in which stem and root anatomy are
more nearly of the same type than in the majority of plants, several
protoxylem strands may be present. The sporangia are axillary or, more
frequently, borne on the upper surface of sporophylls, which are either
identical with or more or less distinct from the foliage leaves; in the latter
case the sporophylls often occur in the form of a well defined strobilus
(cone) at the tips of branches.
The gametophyte (sexual generation) is represented by prothalli which,
in the homosporous genera, may live underground as saprophytes, or the
upper portion may develop chlorophyll and project above the surface of the
ground as an irregularly lobed green structure (e.g. Lycopodium cernuum)
[85]
. In the heterosporous forms the prothalli are much reduced and do not
lead an independent existence outside the spore by the membrane of which
they are always more or less enclosed. The sexual organs are represented by
antheridia and archegonia; the male cells are provided with two cilia except
in Isoetes which has multiciliate antherozoids like those of the ferns.
The existing Lycopods, though widely distributed, never grow in
sufficiently dense masses to the exclusion of other plants to form a
conspicuous feature in the vegetation of a country. The inconspicuous rôle
which they play among the plant-associations of the present era affords a
striking contrast to the abundance of the arborescent species in the
Palaeozoic forests of the northern hemisphere.
• • • • •
Lycopodiaceae. Lycopodium, represented by nearly 100 species, forms a
constituent of most floras: epiphytic species predominate in tropical
regions, while others flourish on the mountains and moorlands of Britain
Page 64
and in other extra-tropical countries. For the most part Lycopodium exhibits
a preference for a moist climate and appears to be well adapted to habitats
where the amount of sunlight is relatively small and the conditions of life
unfavourable for dense vegetation. Mountains and islands constantly recur
as situations from which species have been recorded. Some species are
essentially swamp-plants, e.g. Lycopodium inundatum, a British species,
and L. cruentum from the marshes of Sierra Nevada. A variety of the
American species, L. alopecuroides (var. aquaticum) affords an instance of
a submerged form, which has been collected from an altitude of 12–14,000
ft. on the Andes and Himalayas. It is noteworthy that a considerable variety
of habitats is represented within the limits of the genus and that many
species are sufficiently hardy to exist in circumstances which would be
intolerable to the majority of flowering plants[86].
The British species frequently spoken of as Club Mosses, include
Lycopodium Selago, L. annotinum, L. clavatum, L. alpinum, and L.
inundatum.
• • • • •
Selaginellaceae. The species of Selaginella, over 300 in number, are
widely spread in tropical and subtropical forests, growing on the ground
with trailing, suberect or erect stems climbing over taller and stouter plants
or as pendulous epiphytes on forest trees.
Selaginella lepidophylla, a tropical American type, popularly known as
the Resurrection plant, and often erroneously spoken of as the Rose of
Jericho[87], possesses the power of rolling up its shoots during periods of
drought and furnishes an example of a species adapted to conditions in
marked contrast to those which are most favourable to the majority of
species.
The only British species is Selaginella spinosa named by Linnaeus
Lycopodium selaginoides and occasionally referred to as Selaginella
spinulosa A. Br. (not to be confounded with a Javan species S. spinulosa
Spring[88]).
• • • • •
Isoetaceae. Isoetes (fig. 132), of which Mr Baker in his Handbook of the
Fern-Allies enumerates 49 species, is a type apart, differing in habit as in
a preference for a moist climate and appears to be well adapted to habitats
where the amount of sunlight is relatively small and the conditions of life
unfavourable for dense vegetation. Mountains and islands constantly recur
as situations from which species have been recorded. Some species are
essentially swamp-plants, e.g. Lycopodium inundatum, a British species,
and L. cruentum from the marshes of Sierra Nevada. A variety of the
American species, L. alopecuroides (var. aquaticum) affords an instance of
a submerged form, which has been collected from an altitude of 12–14,000
ft. on the Andes and Himalayas. It is noteworthy that a considerable variety
of habitats is represented within the limits of the genus and that many
species are sufficiently hardy to exist in circumstances which would be
intolerable to the majority of flowering plants[86].
The British species frequently spoken of as Club Mosses, include
Lycopodium Selago, L. annotinum, L. clavatum, L. alpinum, and L.
inundatum.
• • • • •
Selaginellaceae. The species of Selaginella, over 300 in number, are
widely spread in tropical and subtropical forests, growing on the ground
with trailing, suberect or erect stems climbing over taller and stouter plants
or as pendulous epiphytes on forest trees.
Selaginella lepidophylla, a tropical American type, popularly known as
the Resurrection plant, and often erroneously spoken of as the Rose of
Jericho[87], possesses the power of rolling up its shoots during periods of
drought and furnishes an example of a species adapted to conditions in
marked contrast to those which are most favourable to the majority of
species.
The only British species is Selaginella spinosa named by Linnaeus
Lycopodium selaginoides and occasionally referred to as Selaginella
spinulosa A. Br. (not to be confounded with a Javan species S. spinulosa
Spring[88]).
• • • • •
Isoetaceae. Isoetes (fig. 132), of which Mr Baker in his Handbook of the
Fern-Allies enumerates 49 species, is a type apart, differing in habit as in
Page 65
certain other characters from the other members of the Lycopodiales. Some
botanists[89] prefer to include the genus among the Filicales, but the balance
of evidence, including resemblances between Isoetes and extinct
Lycopodiaceous plants, would seem to favour its retention as an aberrant
genus of the group Lycopodiales. Some species are permanently
submerged, others occur in situations intermittently covered with water, and
a few grow in damp soil. Isoetes lacustris is found in mountain tarns and
lakes of Britain and elsewhere in Central and Northern Europe and North
America. Isoetes hystrix[90], a land-form occurs in Guernsey, North-East
France, Spain and Asia Minor.
Lycopodiaceae.
The monotypic genus Phylloglossum, represented by P. Drummondii of
Australia and New Zealand, though interesting from the point of view of its
probable claim to be considered the most primitive type of existing
Lycopodiaceous plants, need not be dealt with in detail. A complete
individual, which does not exceed 4 or 5 cm. in length, consists of a very
small tubercle or protocorm bearing a rosette of slender subulate leaves and
prolonged distally as a simple naked axis which overtops the foliage leaves
and terminates in a compact cluster of small scale-like sporophylls, each
subtending a single sporangium[91].
Lycopodium. It would be out of place in a volume devoted mainly to
fossil plants to attempt a comprehensive account of the general morphology
of recent species, and indeed our knowledge of the anatomical characters of
the genus is still somewhat meagre. For purposes of comparison with
extinct types, it is essential that some of the more important morphological
features of existing species should be briefly considered. The additions
made to our knowledge of the gameophyte[92] of European and tropical
species during the last two decades have revealed a striking diversity in
habit.
In several species, grouped round the widely distributed type Lycopodium
Selago Linn., the comparatively short, erect or suberect, shoots form fairly
compact tufts; the ordinary foliage-leaves function as sporophylls, and the
sporangia are not localised on special portions of shoots. From this type, we
pass to others in which the fertile leaves tend to be confined to the tips of
botanists[89] prefer to include the genus among the Filicales, but the balance
of evidence, including resemblances between Isoetes and extinct
Lycopodiaceous plants, would seem to favour its retention as an aberrant
genus of the group Lycopodiales. Some species are permanently
submerged, others occur in situations intermittently covered with water, and
a few grow in damp soil. Isoetes lacustris is found in mountain tarns and
lakes of Britain and elsewhere in Central and Northern Europe and North
America. Isoetes hystrix[90], a land-form occurs in Guernsey, North-East
France, Spain and Asia Minor.
Lycopodiaceae.
The monotypic genus Phylloglossum, represented by P. Drummondii of
Australia and New Zealand, though interesting from the point of view of its
probable claim to be considered the most primitive type of existing
Lycopodiaceous plants, need not be dealt with in detail. A complete
individual, which does not exceed 4 or 5 cm. in length, consists of a very
small tubercle or protocorm bearing a rosette of slender subulate leaves and
prolonged distally as a simple naked axis which overtops the foliage leaves
and terminates in a compact cluster of small scale-like sporophylls, each
subtending a single sporangium[91].
Lycopodium. It would be out of place in a volume devoted mainly to
fossil plants to attempt a comprehensive account of the general morphology
of recent species, and indeed our knowledge of the anatomical characters of
the genus is still somewhat meagre. For purposes of comparison with
extinct types, it is essential that some of the more important morphological
features of existing species should be briefly considered. The additions
made to our knowledge of the gameophyte[92] of European and tropical
species during the last two decades have revealed a striking diversity in
habit.
In several species, grouped round the widely distributed type Lycopodium
Selago Linn., the comparatively short, erect or suberect, shoots form fairly
compact tufts; the ordinary foliage-leaves function as sporophylls, and the
sporangia are not localised on special portions of shoots. From this type, we
pass to others in which the fertile leaves tend to be confined to the tips of
Page 66
branches, but hardly differ in form from the sterile. A further degree of
specialisation is exhibited by species with well-defined cones composed of
leaves (or bracts), the primary function of which is to bear sporangia and to
afford a protective covering to the strobilus[93].
Lycopodium rufescens Hook. An Andian species with stout
dichotomously branched erect stems bears on the younger shoots crowded
leaves with their thick and broadly triangular laminae pointing upwards, but
on the older and thick shoots the laminae are strongly reflexed (fig. 121, A).
The lower part of the specimen represented in fig. 121, A, shows
tangentially elongated scars and persistent leaf-bases or cushions left on the
stem after the removal of the free portions of the leathery leaves, a surface-
feature which also characterises the Palaeozoic genus Lepidodendron. The
reflexed leaves and persistent leaf-cushions are clearly seen in the piece of
old stem of Lycopodium dichotomum Jacq., a tropical American species
reproduced in fig. 121, B. Such species as L. erythraeum Spring, and others
with stiff lanceolate leaves exhibit a striking resemblance to the more
slender shoots of some recent conifers, more especially Araucaria excelsa,
A. Balansae, Cryptomeria, Dacrydium and other genera.
specialisation is exhibited by species with well-defined cones composed of
leaves (or bracts), the primary function of which is to bear sporangia and to
afford a protective covering to the strobilus[93].
Lycopodium rufescens Hook. An Andian species with stout
dichotomously branched erect stems bears on the younger shoots crowded
leaves with their thick and broadly triangular laminae pointing upwards, but
on the older and thick shoots the laminae are strongly reflexed (fig. 121, A).
The lower part of the specimen represented in fig. 121, A, shows
tangentially elongated scars and persistent leaf-bases or cushions left on the
stem after the removal of the free portions of the leathery leaves, a surface-
feature which also characterises the Palaeozoic genus Lepidodendron. The
reflexed leaves and persistent leaf-cushions are clearly seen in the piece of
old stem of Lycopodium dichotomum Jacq., a tropical American species
reproduced in fig. 121, B. Such species as L. erythraeum Spring, and others
with stiff lanceolate leaves exhibit a striking resemblance to the more
slender shoots of some recent conifers, more especially Araucaria excelsa,
A. Balansae, Cryptomeria, Dacrydium and other genera.
Page 67
Fig. 121. Lycopodium.
A. Lycopodium rufescens.
B. L. dichotomum.
C. L. tetragonum.
D. L. nummularifolium.
E. L. Dalhousianum.
F. L. casuarinoides.
G. L. volubile.
(From specimens in the Cambridge Herbarium and Botanic Garden. M.S.)
A. Lycopodium rufescens.
B. L. dichotomum.
C. L. tetragonum.
D. L. nummularifolium.
E. L. Dalhousianum.
F. L. casuarinoides.
G. L. volubile.
(From specimens in the Cambridge Herbarium and Botanic Garden. M.S.)
Page 68
Fig. 122. Lycopodium squarrosum. The branches of the larger shoot terminate in cones.
(From a plant in the Cambridge Botanic Garden. Reduced.)
In Lycopodium tetragonum Hook., (fig. 121, C), a species from the
Alpine region of the Andes, the long, pendulous and repeatedly forked
branches bear four rows of fleshy ovate leaves and simulate the vegetative
characters of certain conifers.
(From a plant in the Cambridge Botanic Garden. Reduced.)
In Lycopodium tetragonum Hook., (fig. 121, C), a species from the
Alpine region of the Andes, the long, pendulous and repeatedly forked
branches bear four rows of fleshy ovate leaves and simulate the vegetative
characters of certain conifers.
Page 69
Fig. 123. Lycopodium cernuum.
(From a specimen in the Cambridge Herbarium. ½ nat. size.)
L. squarrosum Forst. (fig. 122) a tropical species from India, Polynesia,
and other regions, is characterised by its stout stems reaching a diameter of
2·5 cm., bearing long pendulous branches with large terminal cones
composed of sporophylls differing but slightly from the foliage leaves. The
plant represented in the photograph serves as a good illustration of the
practical identity in habit between Palaeozoic and recent genera.
(From a specimen in the Cambridge Herbarium. ½ nat. size.)
L. squarrosum Forst. (fig. 122) a tropical species from India, Polynesia,
and other regions, is characterised by its stout stems reaching a diameter of
2·5 cm., bearing long pendulous branches with large terminal cones
composed of sporophylls differing but slightly from the foliage leaves. The
plant represented in the photograph serves as a good illustration of the
practical identity in habit between Palaeozoic and recent genera.
Page 70
Fig. 124. Lycopodium obscurum.
L. Dalhousianum Spring, from the mountains of the Malay Peninsula and
Borneo, has larger leaves of finer texture with a distinct midrib reaching a
length of 2–3 cm. (fig. 121, E). Another type is illustrated by L.
nummularifolium Blume, also a Malayan species, in which the leaves are
shorter, broadly oblong or suborbicular, and the branches terminate in
narrow and often very long strobili (sometimes reaching a length of 30 cm.)
with small bracts in striking contrast to the foliage leaves (fig. 121, D). A
similar form of long and slender strobilus occurs in L. Phlegmaria Linn., a
common tropical Lycopod: the frequent forking of the strobili noticed in
this and other species is a character not unknown among fossil cones
(Lepidostrobi).
L. cernuum Linn. (fig. 123), another widely spread tropical type, offers
an even closer resemblance than L. squarrosum to the fossil Lepidodendra.
The stiff erect stem, reaching in some cases a length of several feet, bears
numerous repeatedly forked branches, with crowded linear leaves,
terminating in short cylindrical cones with broadly ovate sporophylls. A
similar habit characterises the North American species L. obscurum Linn.
(fig. 124) bearing cones several centimetres in length.
L. casuarinoides Spring (fig. 121, F) an eastern tropical species, is
worthy of notice as exhibiting a peculiar form of leaf consisting of a very
small lamina, 3 mm. in length, borne on the top of a long decurrent base,
which forms a narrow type of leaf-cushion, bearing some resemblance to
the long and rib-like cushions of certain species of Sigillaria, and recalling
L. Dalhousianum Spring, from the mountains of the Malay Peninsula and
Borneo, has larger leaves of finer texture with a distinct midrib reaching a
length of 2–3 cm. (fig. 121, E). Another type is illustrated by L.
nummularifolium Blume, also a Malayan species, in which the leaves are
shorter, broadly oblong or suborbicular, and the branches terminate in
narrow and often very long strobili (sometimes reaching a length of 30 cm.)
with small bracts in striking contrast to the foliage leaves (fig. 121, D). A
similar form of long and slender strobilus occurs in L. Phlegmaria Linn., a
common tropical Lycopod: the frequent forking of the strobili noticed in
this and other species is a character not unknown among fossil cones
(Lepidostrobi).
L. cernuum Linn. (fig. 123), another widely spread tropical type, offers
an even closer resemblance than L. squarrosum to the fossil Lepidodendra.
The stiff erect stem, reaching in some cases a length of several feet, bears
numerous repeatedly forked branches, with crowded linear leaves,
terminating in short cylindrical cones with broadly ovate sporophylls. A
similar habit characterises the North American species L. obscurum Linn.
(fig. 124) bearing cones several centimetres in length.
L. casuarinoides Spring (fig. 121, F) an eastern tropical species, is
worthy of notice as exhibiting a peculiar form of leaf consisting of a very
small lamina, 3 mm. in length, borne on the top of a long decurrent base,
which forms a narrow type of leaf-cushion, bearing some resemblance to
the long and rib-like cushions of certain species of Sigillaria, and recalling
Page 71
the habit of slender fossil twigs referred to the Coniferae under such names
as Widdringtonites, Cyparissidium, Sphenolepidium.
L. volubile Forst. (fig. 121, G) a New Zealand species, in habit and leaf-
form bears a close resemblance to the Jurassic Lycopodites falcatus Lind.
and Hutt. (fig. 137): it is also a representative of a few species of
Lycopodium which agree with the majority of species of Selaginella in
having two kinds of sterile leaves, comparatively long falcate leaves
forming two lateral rows and smaller appressed leaves on the upper surface
of the branches.
These examples suffice to illustrate the general appearance presented by
the vegetative shoots of recent species of which the foliage leaves vary
considerably—from the small scale-leaves of Lycopodium tetragonum, to
the very slender linear subulate leaves of such a species as L. verticillatum
Linn. or the long and broader lamina of L. Dalhousianum (fig. 121, E). It is
obvious that fragments of the various types preserved as fossils might well
be mistaken either for some of the larger mosses or for twigs of conifers. As
Dr Bommer[94] has pointed out in his interesting paper on “Les causes
d’erreur dans l’étude des empreintes végétales” some dicotyledonous plants
may also simulate the habit of Lycopods: he cites Phyllachne clavigera
Hook (Candolleaceae), Tafalla graveolens Wedd (Compositae) and
Lavoisiera lycopodioides Gard. (Melastomataceae). Another point
illustrated by fig. 121 is the close agreement in habit and in the form of the
leaves and leaf-cushions between the recent plants and the Palaeozoic
Lepidodendreae.
In his masterly essay “On the vegetation of the Carboniferous Period, as
compared with that of the present day” Sir Joseph Hooker called attention
to the variation in the shape and arrangement of the leaves in the same
species of Lycopodium. The three woodcuts which he publishes of
Lycopodium densum, a New Zealand species, afford striking examples of
the diversity in habit and leaf-form and justify his warning “that if the
species of Lepidodendron were as prone to vary in the foliage as are those
of Lycopodium, our available means for distinguishing them are wholly
insufficient[95].”
As we have already noticed, there is a considerable diversity among
recent species, both as regards habitat and habit; in the anatomy of the stem
as Widdringtonites, Cyparissidium, Sphenolepidium.
L. volubile Forst. (fig. 121, G) a New Zealand species, in habit and leaf-
form bears a close resemblance to the Jurassic Lycopodites falcatus Lind.
and Hutt. (fig. 137): it is also a representative of a few species of
Lycopodium which agree with the majority of species of Selaginella in
having two kinds of sterile leaves, comparatively long falcate leaves
forming two lateral rows and smaller appressed leaves on the upper surface
of the branches.
These examples suffice to illustrate the general appearance presented by
the vegetative shoots of recent species of which the foliage leaves vary
considerably—from the small scale-leaves of Lycopodium tetragonum, to
the very slender linear subulate leaves of such a species as L. verticillatum
Linn. or the long and broader lamina of L. Dalhousianum (fig. 121, E). It is
obvious that fragments of the various types preserved as fossils might well
be mistaken either for some of the larger mosses or for twigs of conifers. As
Dr Bommer[94] has pointed out in his interesting paper on “Les causes
d’erreur dans l’étude des empreintes végétales” some dicotyledonous plants
may also simulate the habit of Lycopods: he cites Phyllachne clavigera
Hook (Candolleaceae), Tafalla graveolens Wedd (Compositae) and
Lavoisiera lycopodioides Gard. (Melastomataceae). Another point
illustrated by fig. 121 is the close agreement in habit and in the form of the
leaves and leaf-cushions between the recent plants and the Palaeozoic
Lepidodendreae.
In his masterly essay “On the vegetation of the Carboniferous Period, as
compared with that of the present day” Sir Joseph Hooker called attention
to the variation in the shape and arrangement of the leaves in the same
species of Lycopodium. The three woodcuts which he publishes of
Lycopodium densum, a New Zealand species, afford striking examples of
the diversity in habit and leaf-form and justify his warning “that if the
species of Lepidodendron were as prone to vary in the foliage as are those
of Lycopodium, our available means for distinguishing them are wholly
insufficient[95].”
As we have already noticed, there is a considerable diversity among
recent species, both as regards habitat and habit; in the anatomy of the stem
Page 72
also corresponding variations occur within the limits of a well-defined
generic type of stele. In species with creeping stems, such as L. clavatum[96],
the stele exhibits an arrangement of vascular tissue characteristic of the
plagiotropic forms. The xylem consists of more or less horizontal plates of
scalariform tracheae, each surrounded by small-celled parenchyma,
alternating with bands or groups of somewhat ill-defined phloem. The
protoxylem and protophloem elements occupy an external position
(exarch), pointing to a centripetal development of the metaxylem. This
centripetal or root-like character of the primary xylem is an important
feature in recent as in fossil Lycopods. The close agreement between the
roots and stems of recent species in the disposition of the vascular elements
also denotes a simpler type of anatomy than occurs in the majority of
vascular plants in which stem and root have more pronounced structural
peculiarities. A pericycle, 2–6 cells in breadth, encloses the xylem and
phloem bands and this is succeeded by an endodermis, 2–3 cells broad, with
vaguely defined limits. In L. clavatum, as in L. alpinum, another British
species, the broad cortex is differentiated into three fairly distinct regions;
abutting on the endodermis is a zone several layers broad of thick-walled
cells constituting an inner cortex modified for protection and support; the
central region consists of larger and thinner-walled cells adapted for water-
storage and aeration; beyond this is an outer cortical zone of firmer and
thicker elements. The prominent leaf-bases or leaf-cushions (fig. 125, A, lc)
give to the surface of a transverse section a characteristic appearance which
presents the closest agreement with that of the younger shoots of
Lepidodendron. From the peripheral protoxylem groups small strands of
xylem are given off, which follow a steeply ascending course through the
cortex to the single-veined leaves. The leaf-traces, in several species at
least, are characterised by a mesarch structure (fig. 125, F, G), the spiral
protoxylem elements occupying an approximately central position. The
mesophyll of the leaves varies in regard to the extent of differentiation into
a palisade and spongy parenchyma; in all cases there is a single vascular
bundle occasionally accompanied by a secretory duct.
generic type of stele. In species with creeping stems, such as L. clavatum[96],
the stele exhibits an arrangement of vascular tissue characteristic of the
plagiotropic forms. The xylem consists of more or less horizontal plates of
scalariform tracheae, each surrounded by small-celled parenchyma,
alternating with bands or groups of somewhat ill-defined phloem. The
protoxylem and protophloem elements occupy an external position
(exarch), pointing to a centripetal development of the metaxylem. This
centripetal or root-like character of the primary xylem is an important
feature in recent as in fossil Lycopods. The close agreement between the
roots and stems of recent species in the disposition of the vascular elements
also denotes a simpler type of anatomy than occurs in the majority of
vascular plants in which stem and root have more pronounced structural
peculiarities. A pericycle, 2–6 cells in breadth, encloses the xylem and
phloem bands and this is succeeded by an endodermis, 2–3 cells broad, with
vaguely defined limits. In L. clavatum, as in L. alpinum, another British
species, the broad cortex is differentiated into three fairly distinct regions;
abutting on the endodermis is a zone several layers broad of thick-walled
cells constituting an inner cortex modified for protection and support; the
central region consists of larger and thinner-walled cells adapted for water-
storage and aeration; beyond this is an outer cortical zone of firmer and
thicker elements. The prominent leaf-bases or leaf-cushions (fig. 125, A, lc)
give to the surface of a transverse section a characteristic appearance which
presents the closest agreement with that of the younger shoots of
Lepidodendron. From the peripheral protoxylem groups small strands of
xylem are given off, which follow a steeply ascending course through the
cortex to the single-veined leaves. The leaf-traces, in several species at
least, are characterised by a mesarch structure (fig. 125, F, G), the spiral
protoxylem elements occupying an approximately central position. The
mesophyll of the leaves varies in regard to the extent of differentiation into
a palisade and spongy parenchyma; in all cases there is a single vascular
bundle occasionally accompanied by a secretory duct.
Page 73
Fig. 125.
A. Lycopodium dichotomum. Transverse section of stem: lc, leaf-cushion; lt, leaf-
trace; R, roots.
B. L. cernuum, portion of cortex of fig. H, enlarged.
C. L. saururus. Cortex: lt, leaf-trace; a, thin-walled tissue; b, thick-walled tissue; lc,
lacuna.
D. L. saururus. Stele: x, xylem; p, phloem.
E. Portion of fig. D, enlarged: px, protoxylem; p, phloem.
F. Transverse section of leaf of Lycopodium.
G. Vascular bundle of leaf: px, protoxylem.
H. L. cernuum: b, branch of stele; c–c″, cortex; s, space in cortex; lt, leaf-trace.
I. Stele of fig. H, enlarged (phloem omitted).
A. Lycopodium dichotomum. Transverse section of stem: lc, leaf-cushion; lt, leaf-
trace; R, roots.
B. L. cernuum, portion of cortex of fig. H, enlarged.
C. L. saururus. Cortex: lt, leaf-trace; a, thin-walled tissue; b, thick-walled tissue; lc,
lacuna.
D. L. saururus. Stele: x, xylem; p, phloem.
E. Portion of fig. D, enlarged: px, protoxylem; p, phloem.
F. Transverse section of leaf of Lycopodium.
G. Vascular bundle of leaf: px, protoxylem.
H. L. cernuum: b, branch of stele; c–c″, cortex; s, space in cortex; lt, leaf-trace.
I. Stele of fig. H, enlarged (phloem omitted).
Page 74
In erect stems of Lycopodium, as represented by L. cernuum (figs. 123,
125, H, I), L. Dalhousianum, L. squarrosum (fig. 122) and many others, the
stele presents a characteristic appearance due to the xylem plates being
broken up into detached groups or short uniseriate bands with the
interspaces occupied by phloem islands. This type of structure bears a
superficial resemblance to that in the single stele of certain species of the
fern Lygodium[97], but it is distinguished by the islands of phloem scattered
through the stele. In other species the xylem tends to assume the form of a
Maltese cross (e.g. L. serratum Thbg.) or it may be disposed as V-shaped
and sinuous bands terminating in broad truncate ends composed of
protoxylem elements. This form of the xylem and the distribution of the
phloem groups are shown in fig. 125, D, E, drawn from a section of a plant
of Lycopodium saururus Lam.[98] collected by Mr A. W. Hill at an altitude of
15,000 feet on the Andes of Peru. The position of the protoxylem is shown
fig. 125, E, px.
While several species possess a cortex of three distinct zones (fig. 125,
H, c, c′, c″), in others the extra-stelar tissue is much more homogeneous,
consisting of thin-walled parenchyma or in some cases of thick-walled
elements; as a general rule, however, there is a tendency towards a more
compact arrangement in the inner and outer portions of the cortex as
contrasted with the larger and more loosely connected cells of the middle
region. In certain types the middle cortex contains fairly large spaces, as in
the swamp-species L. inundatum, which with L. alopecuroides exhibits
another feature of some interest first described by Hegelmaier[99]. If a
transverse section of the stem of L. inundatum be examined the leaf-traces
are seen to be accompanied by a circular canal containing mucilage which
extends into the lamina of the leaf. In a specimen of L. cernuum[100] obtained
at a height of 2500 ft. by Professor Stanley Gardiner in the Fiji Islands, the
leaf-traces (fig. 125, B lt) were found to be accompanied for part of their
course by a well-marked secretory space (fig. 125, B, s). There is little
doubt that the presence of these mucilage canals is directly connected with
a certain type of habitat[101] and attention is called to them in view of a
resemblance which they offer to a characteristic strand of tissue, known as
the parichnos, which is associated with the leaf-traces of Lepidodendreae
and Sigillarieae. In the section shown in fig. 125, H, the xylem of the stele
forms more continuous bands than is often the case in L. cernuum which
has already been described as having its xylem in small detached groups.
125, H, I), L. Dalhousianum, L. squarrosum (fig. 122) and many others, the
stele presents a characteristic appearance due to the xylem plates being
broken up into detached groups or short uniseriate bands with the
interspaces occupied by phloem islands. This type of structure bears a
superficial resemblance to that in the single stele of certain species of the
fern Lygodium[97], but it is distinguished by the islands of phloem scattered
through the stele. In other species the xylem tends to assume the form of a
Maltese cross (e.g. L. serratum Thbg.) or it may be disposed as V-shaped
and sinuous bands terminating in broad truncate ends composed of
protoxylem elements. This form of the xylem and the distribution of the
phloem groups are shown in fig. 125, D, E, drawn from a section of a plant
of Lycopodium saururus Lam.[98] collected by Mr A. W. Hill at an altitude of
15,000 feet on the Andes of Peru. The position of the protoxylem is shown
fig. 125, E, px.
While several species possess a cortex of three distinct zones (fig. 125,
H, c, c′, c″), in others the extra-stelar tissue is much more homogeneous,
consisting of thin-walled parenchyma or in some cases of thick-walled
elements; as a general rule, however, there is a tendency towards a more
compact arrangement in the inner and outer portions of the cortex as
contrasted with the larger and more loosely connected cells of the middle
region. In certain types the middle cortex contains fairly large spaces, as in
the swamp-species L. inundatum, which with L. alopecuroides exhibits
another feature of some interest first described by Hegelmaier[99]. If a
transverse section of the stem of L. inundatum be examined the leaf-traces
are seen to be accompanied by a circular canal containing mucilage which
extends into the lamina of the leaf. In a specimen of L. cernuum[100] obtained
at a height of 2500 ft. by Professor Stanley Gardiner in the Fiji Islands, the
leaf-traces (fig. 125, B lt) were found to be accompanied for part of their
course by a well-marked secretory space (fig. 125, B, s). There is little
doubt that the presence of these mucilage canals is directly connected with
a certain type of habitat[101] and attention is called to them in view of a
resemblance which they offer to a characteristic strand of tissue, known as
the parichnos, which is associated with the leaf-traces of Lepidodendreae
and Sigillarieae. In the section shown in fig. 125, H, the xylem of the stele
forms more continuous bands than is often the case in L. cernuum which
has already been described as having its xylem in small detached groups.
Page 75
The presence of the smaller branch-stele (fig. 125, H, b) affords an example
of monopodial branching. The outer cortex of L. saururus (fig. 125, C)
exhibits a somewhat unusual feature in the distribution of the thicker-walled
tissue (b) which encloses a patch of more delicate parenchyma (a) with
large lacunae (lc) in the region of the leaf-bases, and presents the
appearance of an irregular reticulum. This arrangement of the mechanical
tissue in the outer cortex is comparable with that in stems of some species
of Sigillaria.
In certain species of Lycopodium the roots[102], which arise endogenously
from the axial vascular cylinder, instead of passing through the cortex of the
stem by the shortest route, bend downwards and bore their way in a more or
less vertical direction before emerging at or near the base of the aerial
shoot. The transverse section of L. dichotomum represented in fig. 125, A,
shows several roots (R) in the cortex; they consist of a xylem strand of
circular or crescentric form accompanied by phloem and enclosed by
several layers of root-cortex. The roots of Lycopodium do not always
present so simple a structure as those of L. dichotomum; the xylem may
have an irregularly stellate form with as many as ten protoxylem groups.
Reproductive Shoots[103]. In Lycopodium Selago the foliage leaves serve
also as sporophylls and, as Professor Bower[104] has pointed out, the
branches exhibit to some extent a zonal alternation of sterile and fertile
leaves; in other species, in which foliage leaves and sporophylls are
practically identical, the sporangia occur sporadically on the ordinary
leaves. In species with well-defined terminal cones the lower sporophylls
may bear arrested sporangia and thus form transitional stages between
sterile and fertile leaves, a feature which occurs also in the male and female
flowers of many recent Araucarieae[105]. The sporangia[106] (fig. 126, D, F)
are usually reniform and compressed in a direction parallel to the surface of
the cone-scales; they are developed from the upper surface and close to the
base of the fertile leaf to which they are attached by a short and thick stalk
(e.g. L. inundatum) or by a longer and more slender pedicel (L. Phlegmaria,
fig. 126, E). On maturity the sporangia open as two valves in the plane of
compression and the line of dehiscence is determined in some species at
least by the occurrence of smaller cells in the wall. In transverse sections of
cones in which the sporangia are strongly saddle-shaped, the sporophylls
may appear to bear two sporangia. This is well shown in the section of a
of monopodial branching. The outer cortex of L. saururus (fig. 125, C)
exhibits a somewhat unusual feature in the distribution of the thicker-walled
tissue (b) which encloses a patch of more delicate parenchyma (a) with
large lacunae (lc) in the region of the leaf-bases, and presents the
appearance of an irregular reticulum. This arrangement of the mechanical
tissue in the outer cortex is comparable with that in stems of some species
of Sigillaria.
In certain species of Lycopodium the roots[102], which arise endogenously
from the axial vascular cylinder, instead of passing through the cortex of the
stem by the shortest route, bend downwards and bore their way in a more or
less vertical direction before emerging at or near the base of the aerial
shoot. The transverse section of L. dichotomum represented in fig. 125, A,
shows several roots (R) in the cortex; they consist of a xylem strand of
circular or crescentric form accompanied by phloem and enclosed by
several layers of root-cortex. The roots of Lycopodium do not always
present so simple a structure as those of L. dichotomum; the xylem may
have an irregularly stellate form with as many as ten protoxylem groups.
Reproductive Shoots[103]. In Lycopodium Selago the foliage leaves serve
also as sporophylls and, as Professor Bower[104] has pointed out, the
branches exhibit to some extent a zonal alternation of sterile and fertile
leaves; in other species, in which foliage leaves and sporophylls are
practically identical, the sporangia occur sporadically on the ordinary
leaves. In species with well-defined terminal cones the lower sporophylls
may bear arrested sporangia and thus form transitional stages between
sterile and fertile leaves, a feature which occurs also in the male and female
flowers of many recent Araucarieae[105]. The sporangia[106] (fig. 126, D, F)
are usually reniform and compressed in a direction parallel to the surface of
the cone-scales; they are developed from the upper surface and close to the
base of the fertile leaf to which they are attached by a short and thick stalk
(e.g. L. inundatum) or by a longer and more slender pedicel (L. Phlegmaria,
fig. 126, E). On maturity the sporangia open as two valves in the plane of
compression and the line of dehiscence is determined in some species at
least by the occurrence of smaller cells in the wall. In transverse sections of
cones in which the sporangia are strongly saddle-shaped, the sporophylls
may appear to bear two sporangia. This is well shown in the section of a
Page 76
cone of L. clavatum shown in fig. 126, F. The sporangia a and b are cut
through in an approximately median plane showing the irregular outline of
the sterile pad (p) of tissue in the sporogenous cavity. Those at c and d have
been traversed at a lower level and the two lobes of the saddle-shaped
sporangia are cut below the attachment to the sporophyll. The distal laminae
of the sporophylls, cut at different levels, are seen at the periphery of the
cone.
through in an approximately median plane showing the irregular outline of
the sterile pad (p) of tissue in the sporogenous cavity. Those at c and d have
been traversed at a lower level and the two lobes of the saddle-shaped
sporangia are cut below the attachment to the sporophyll. The distal laminae
of the sporophylls, cut at different levels, are seen at the periphery of the
cone.
Page 77
Fig. 126.
A. Lycopodium cernuum, longitudinal section of strobilus; a, band of lignified cells.
B. L. cernuum. Cell from sporangium wall.
C. L. cernuum. Sporophyll and sporangium; lt, vascular bundle.
D. L. clavatum. Part of radial longitudinal section of strobilus; p, sterile tissue.
E. L. Phlegmaria. Sporophyll and stalked sporangium.
F. L. clavatum. Transverse section of strobilus; p, sterile pad.
In longitudinal radial section of some cones the sporangia appear to
occupy an axillary position, but in others (e.g. L. clavatum) they are
attached to the horizontal portion of the sporophyll almost midway between
the axis of the cone and the upturned distal end of the sporophyll (fig. 126,
A. Lycopodium cernuum, longitudinal section of strobilus; a, band of lignified cells.
B. L. cernuum. Cell from sporangium wall.
C. L. cernuum. Sporophyll and sporangium; lt, vascular bundle.
D. L. clavatum. Part of radial longitudinal section of strobilus; p, sterile tissue.
E. L. Phlegmaria. Sporophyll and stalked sporangium.
F. L. clavatum. Transverse section of strobilus; p, sterile pad.
In longitudinal radial section of some cones the sporangia appear to
occupy an axillary position, but in others (e.g. L. clavatum) they are
attached to the horizontal portion of the sporophyll almost midway between
the axis of the cone and the upturned distal end of the sporophyll (fig. 126,
Page 78
D). The wall of a sporangium frequently consists of 2–3 cell-layers and in
some cases (e.g. L. dichotomum), it may reach a thickness of seven layers,
resembling in this respect the more bulky sporangia of a certain type of
Lepidodendroid cone. The sporogenous tissue is separated from the stalk of
the sporangium by a mass of parenchymatous tissue which may project as a
prominent pad (fig. 126, D, F, p) into the interior of the sporogenous cavity.
This basal tissue (the subarchesporial pad of Bower[107]) has been observed
in L. clavatum to send up irregular processes of sterile cells among the
developing spores, suggesting a comparison with the trabeculae which form
a characteristic feature of the sporangia of Isoetes and with similar sterile
strands noticed by Bower[108] in Lepidostrobus (cone of Lepidodendron).
Each sporophyll is supplied by a single vascular bundle which according
to published statements never sends a branch to the sporangium base. The
fertile tips of the foliage shoots of L. cernuum (figs. 126, A–C) afford good
examples of specialised cones. The surface of the cone is covered by the
broadly triangular laminae of sporophylls (fig. 126, C) which in their
fimbriate margins resemble the Palaeozoic cone-scales described by Dr
Kidston[109] as Lepidostrobus fimbriatus. The distal portions of the
sporophylls are prolonged downwards (fig. 126, A) to afford protection to
the lower sporangia, their efficiency being increased by the lignified and
thicker walls (A, a) of the cells in the lower portion of the laminar
expansion. The cells of the sporangial wall are provided with strengthening
bands which in surface-view (fig. 126, B) present the appearance of
prominent pegs. Since the appearance of Miss Sykes’s paper on the
sporangium-bearing organs of the Lycopodiaceae, Dr Lang[110] has
published a more complete account of the structure of the strobilus of
Lycopodium cernuum in which he records certain features of special
interest. The importance of these morphological characters is increased by
their agreement, as shown by Lang, with those of the Palaeozoic cone
Spencerites[111]. The sporophylls of a cone (12 mm. long by 3 mm. in
diameter) of Lycopodium cernuum show an abrupt transition from the
foliage leaves, but like these they occur in alternate whorls of five. A large
sporangium is attached to the upper face of each sporophyll close to the
base of the obliquely vertical distal lamina (fig. 127); each sporophyll,
which is supplied with a single vascular bundle, has a large mucilage-cavity
(m) in its lower region. “The mucilaginous change” in the sub-sporangial
portion of a sporophyll “extends to the surface involving the epidermis, so
some cases (e.g. L. dichotomum), it may reach a thickness of seven layers,
resembling in this respect the more bulky sporangia of a certain type of
Lepidodendroid cone. The sporogenous tissue is separated from the stalk of
the sporangium by a mass of parenchymatous tissue which may project as a
prominent pad (fig. 126, D, F, p) into the interior of the sporogenous cavity.
This basal tissue (the subarchesporial pad of Bower[107]) has been observed
in L. clavatum to send up irregular processes of sterile cells among the
developing spores, suggesting a comparison with the trabeculae which form
a characteristic feature of the sporangia of Isoetes and with similar sterile
strands noticed by Bower[108] in Lepidostrobus (cone of Lepidodendron).
Each sporophyll is supplied by a single vascular bundle which according
to published statements never sends a branch to the sporangium base. The
fertile tips of the foliage shoots of L. cernuum (figs. 126, A–C) afford good
examples of specialised cones. The surface of the cone is covered by the
broadly triangular laminae of sporophylls (fig. 126, C) which in their
fimbriate margins resemble the Palaeozoic cone-scales described by Dr
Kidston[109] as Lepidostrobus fimbriatus. The distal portions of the
sporophylls are prolonged downwards (fig. 126, A) to afford protection to
the lower sporangia, their efficiency being increased by the lignified and
thicker walls (A, a) of the cells in the lower portion of the laminar
expansion. The cells of the sporangial wall are provided with strengthening
bands which in surface-view (fig. 126, B) present the appearance of
prominent pegs. Since the appearance of Miss Sykes’s paper on the
sporangium-bearing organs of the Lycopodiaceae, Dr Lang[110] has
published a more complete account of the structure of the strobilus of
Lycopodium cernuum in which he records certain features of special
interest. The importance of these morphological characters is increased by
their agreement, as shown by Lang, with those of the Palaeozoic cone
Spencerites[111]. The sporophylls of a cone (12 mm. long by 3 mm. in
diameter) of Lycopodium cernuum show an abrupt transition from the
foliage leaves, but like these they occur in alternate whorls of five. A large
sporangium is attached to the upper face of each sporophyll close to the
base of the obliquely vertical distal lamina (fig. 127); each sporophyll,
which is supplied with a single vascular bundle, has a large mucilage-cavity
(m) in its lower region. “The mucilaginous change” in the sub-sporangial
portion of a sporophyll “extends to the surface involving the epidermis, so
Page 79
that this portion of the sporophyll-base may be described as consisting of a
mass of mucilage bounded below by a structureless membrane[112].”
Dehiscence of the sporangia occurs at the middle of the distal face (fig. 127,
x). As seen in the radial section (fig. 127, ma) the outer margin of the base
of the sporophyll bears a short outgrowth. The leaf-bases of each whorl
hang down between the sporangia of the alternating whorl below, and the
base of each sporophyll is coherent with the margins of the two sporophylls
of the next lower whorl between which it lies, the sporangia being thus
closely packed and lying in a pocket “open only on the outer surface of the
cone.” Fig. 128 represents a transverse section through a cone in the plane
AA of fig. 127; this traverses the sporangia and their subtending bracts (b)
of one whorl and the dependent bases of the sporophylls of the next higher
whorl in the region of the mucilage-sacs (m), which are bounded at the
periphery by the outer tissue of the sporophylls (a). A transverse section in
the plane BB of fig. 127 is shown in fig. 129: the pedicels and a part of each
vascular strand are seen at b radiating from the axis of the cone; one
sporophyll (sp, a) is cut through in the region of the pad of tracheal tissue
that characterises the short sporangial stalks. The upper portions of the
sporangia of the next lower whorl, which project upwards against the
mucilaginous bases of the sporophylls above (cf. fig. 127, BB) are shown at
c and external to them, at a, the section has cut through the outer persistent
portions of these sporophyll bases.
mass of mucilage bounded below by a structureless membrane[112].”
Dehiscence of the sporangia occurs at the middle of the distal face (fig. 127,
x). As seen in the radial section (fig. 127, ma) the outer margin of the base
of the sporophyll bears a short outgrowth. The leaf-bases of each whorl
hang down between the sporangia of the alternating whorl below, and the
base of each sporophyll is coherent with the margins of the two sporophylls
of the next lower whorl between which it lies, the sporangia being thus
closely packed and lying in a pocket “open only on the outer surface of the
cone.” Fig. 128 represents a transverse section through a cone in the plane
AA of fig. 127; this traverses the sporangia and their subtending bracts (b)
of one whorl and the dependent bases of the sporophylls of the next higher
whorl in the region of the mucilage-sacs (m), which are bounded at the
periphery by the outer tissue of the sporophylls (a). A transverse section in
the plane BB of fig. 127 is shown in fig. 129: the pedicels and a part of each
vascular strand are seen at b radiating from the axis of the cone; one
sporophyll (sp, a) is cut through in the region of the pad of tracheal tissue
that characterises the short sporangial stalks. The upper portions of the
sporangia of the next lower whorl, which project upwards against the
mucilaginous bases of the sporophylls above (cf. fig. 127, BB) are shown at
c and external to them, at a, the section has cut through the outer persistent
portions of these sporophyll bases.
Page 80
Fig. 127. Radial longitudinal section of the cone of Lycopodium cernuum. (After Lang.)
Fig. 128. Transverse section of the cone of Lycopodium cernuum, in its plane AA of fig. 127.
(After Lang.)
Fig. 128. Transverse section of the cone of Lycopodium cernuum, in its plane AA of fig. 127.
(After Lang.)
Page 81
Fig. 129. Transverse section of the cone of Lycopodium cernuum in the plane BB of fig. 127.
(After Lang.)
As Lang points out, this highly complex structure is an expression of the
complete protection afforded to the sporangia of a plant met with in
exposed situations in the tropics; it is also of importance from a
morphological standpoint as exhibiting an agreement with the extinct type
of Lycopod cone represented by Spencerites.
Selaginellaceae.
Selaginella differs from Lycopodium in the production of two kinds of
spores, megaspores and microspores, and, in the great majority of species,
in the dimorphic character of the foliage leaves, which are usually arranged
in four rows, the laminae of the upper rows being very much smaller than
those of the lower (fig. 130, 1–3). The smaller leaves are shown more
clearly in fig. 130, 1a. It is obvious from an examination of a Selaginella
shoot, such as is shown in fig. 130, that in fossil specimens it would often
be almost impossible to recognise the existence of two kinds of leaves.
Some species, e.g. Selaginella spinosa[113], the sole British representative of
the genus, are homophyllous and agree in this respect with most species of
Lycopodium. Another feature characteristic of Selaginella, as contrasted
with Lycopodium, is the presence of a ligule in both foliage leaves and
(After Lang.)
As Lang points out, this highly complex structure is an expression of the
complete protection afforded to the sporangia of a plant met with in
exposed situations in the tropics; it is also of importance from a
morphological standpoint as exhibiting an agreement with the extinct type
of Lycopod cone represented by Spencerites.
Selaginellaceae.
Selaginella differs from Lycopodium in the production of two kinds of
spores, megaspores and microspores, and, in the great majority of species,
in the dimorphic character of the foliage leaves, which are usually arranged
in four rows, the laminae of the upper rows being very much smaller than
those of the lower (fig. 130, 1–3). The smaller leaves are shown more
clearly in fig. 130, 1a. It is obvious from an examination of a Selaginella
shoot, such as is shown in fig. 130, that in fossil specimens it would often
be almost impossible to recognise the existence of two kinds of leaves.
Some species, e.g. Selaginella spinosa[113], the sole British representative of
the genus, are homophyllous and agree in this respect with most species of
Lycopodium. Another feature characteristic of Selaginella, as contrasted
with Lycopodium, is the presence of a ligule in both foliage leaves and
Page 82
sporophylls. This is a colourless thin lamina attached by a comparatively
stout foot to the base of a pit on the upper surface and close to the lower
edge of the leaf (fig. 130, 4, l; fig. 131, E, F, l).
Fig. 130. Selaginella grandis. (1–3, nat. size.)
In an erect species, such as S. grandis Moore[114] (fig. 130 and fig. 131,
G) from Borneo, the main shoots, which may attain a height of 2–3 feet,
bear small and inconspicuous leaves of one kind, but the lateral and
repeatedly forked shoots are heterophyllous. The passage from the
homophyllous to the heterophyllous arrangement is shown in the transition
from the erect to the dorsiventral habit of the lateral shoots (fig. 130, 2).
stout foot to the base of a pit on the upper surface and close to the lower
edge of the leaf (fig. 130, 4, l; fig. 131, E, F, l).
Fig. 130. Selaginella grandis. (1–3, nat. size.)
In an erect species, such as S. grandis Moore[114] (fig. 130 and fig. 131,
G) from Borneo, the main shoots, which may attain a height of 2–3 feet,
bear small and inconspicuous leaves of one kind, but the lateral and
repeatedly forked shoots are heterophyllous. The passage from the
homophyllous to the heterophyllous arrangement is shown in the transition
from the erect to the dorsiventral habit of the lateral shoots (fig. 130, 2).
Page 83
The monopodially or dichotomously branched shoots produce long naked
axes at the forks; these grow downwards to the ground where they develop
numerous dichotomously forked branches. For certain reasons these naked
aerial axes were named rhizophores and have always been styled shoots, the
term root being restricted to repeatedly forked branches which the
rhizophores produce in the soil. It has, however, been shown by Professor
Harvey-Gibson[115] that there is no sufficient reason for drawing any
morphological distinction between rhizophores and roots, the term root
being applicable to both.
Our knowledge of the anatomy of Selaginella, thanks chiefly to the
researches of Harvey-Gibson[116], is much more complete than in the case of
Lycopodium. The stems, which may be either trailing or erect, are usually
dorsiventral, and it is noteworthy that different shoots of the same plant or
even the same axis in different regions may exhibit considerable variation
in the structure and arrangement of the vascular tissue. In the well-known
species, Selaginella Martensii, the stem, which is partly trailing, partly
ascending, possesses a single ribbon-shaped stele composed of scalariform
tracheids with two marginal protoxylems formed by the fusion of the leaf-
traces of the dorsal and ventral leaves respectively. As in Lycopodium the
metaxylem tracheae are as a rule scalariform, but reticulate xylem elements
are by no means unknown. The tracheal band, surrounded by
parenchymatous elements, is enclosed by phloem with external
protophloem elements. The characteristic features of the stele are shown in
the diagrammatic drawing of a section of another species—S. Willdenowii
—represented in fig. 131, A.
axes at the forks; these grow downwards to the ground where they develop
numerous dichotomously forked branches. For certain reasons these naked
aerial axes were named rhizophores and have always been styled shoots, the
term root being restricted to repeatedly forked branches which the
rhizophores produce in the soil. It has, however, been shown by Professor
Harvey-Gibson[115] that there is no sufficient reason for drawing any
morphological distinction between rhizophores and roots, the term root
being applicable to both.
Our knowledge of the anatomy of Selaginella, thanks chiefly to the
researches of Harvey-Gibson[116], is much more complete than in the case of
Lycopodium. The stems, which may be either trailing or erect, are usually
dorsiventral, and it is noteworthy that different shoots of the same plant or
even the same axis in different regions may exhibit considerable variation
in the structure and arrangement of the vascular tissue. In the well-known
species, Selaginella Martensii, the stem, which is partly trailing, partly
ascending, possesses a single ribbon-shaped stele composed of scalariform
tracheids with two marginal protoxylems formed by the fusion of the leaf-
traces of the dorsal and ventral leaves respectively. As in Lycopodium the
metaxylem tracheae are as a rule scalariform, but reticulate xylem elements
are by no means unknown. The tracheal band, surrounded by
parenchymatous elements, is enclosed by phloem with external
protophloem elements. The characteristic features of the stele are shown in
the diagrammatic drawing of a section of another species—S. Willdenowii
—represented in fig. 131, A.
Page 84
Fig. 131.
A. Selaginella Willdenowii. Transverse section of stem: a, outer cortex; p, phloem; t,
trabeculae.
B. S. spinosa, stem: px, protoxylem.
C. S. laevigata var. Lyallii, section of stele: t, ridge of xylem cylinder; e, endodermis.
D. S. rupestris, seedlings with cotyledons (c) protruding beyond the sporophylls (b).
E. Transverse section of Selaginella leaf-base: l, ligule; lt, leaf-trace.
F. Portion of G. enlarged.
G. S. grandis. Longitudinal section of strobilus: bb, sporophyll-trace; l, ligule.
(A, B, C, E, F, after Harvey-Gibson; D, after Miss Lyon.)
A pericycle composed of one or two layers of chlorophyll-containing
cells encircles the whole stele which is suspended in a lacuna by trabeculae
A. Selaginella Willdenowii. Transverse section of stem: a, outer cortex; p, phloem; t,
trabeculae.
B. S. spinosa, stem: px, protoxylem.
C. S. laevigata var. Lyallii, section of stele: t, ridge of xylem cylinder; e, endodermis.
D. S. rupestris, seedlings with cotyledons (c) protruding beyond the sporophylls (b).
E. Transverse section of Selaginella leaf-base: l, ligule; lt, leaf-trace.
F. Portion of G. enlarged.
G. S. grandis. Longitudinal section of strobilus: bb, sporophyll-trace; l, ligule.
(A, B, C, E, F, after Harvey-Gibson; D, after Miss Lyon.)
A pericycle composed of one or two layers of chlorophyll-containing
cells encircles the whole stele which is suspended in a lacuna by trabeculae
Page 85
(fig. 131, A, B, t) connecting the pericycle with the inner edge of the broad
cortex. The trabeculae consist in part of endodermal cells characterised by
cuticular bands. The cortex is usually differentiated into three fairly distinct
regions. Mechanical tissue of thick-walled fibres constitutes the outer
region (a); the middle cortex consists of thinner-walled parenchyma, the
elements of which become smaller and rather more compactly arranged in
the inner zone. The middle cortex is frequently characterised by the
presence of spaces and by the hyphal or trabecular structure of the tissue, a
feature which, as Bower[117] pointed out, is common to many recent and
fossil members of the Lycopodiales. In some cases, e.g. S. erythropus, from
tropical America, the cortex of the creeping stem consists entirely of thick-
walled cells. Selaginella grandis (fig. 130) has “a short decumbent stem
rooted at close intervals[118],” from which thick erect aerial shoots rise to a
height of one foot or more. In the apical region these erect axes give off
repeatedly forked foliage shoots on which the spiral phyllotaxis of the
homophyllous axis is gradually replaced by four rows of two kinds of
leaves (fig. 130, 2). The anatomy of this species agrees with that of S.
Martensii. The trailing or semi-erect and homophyllous shoots of
Selaginella spinosa[119] present a distinct type of vascular anatomy. The
upper part of the ascending stem has an axial strand of xylem with seven
peripheral groups of spiral protoxylem tracheae (fig. 131, B); in the trailing
portion of the shoot the protoxylem elements occur as one central group in
the solid rod of metaxylem through which the leaf-traces pass on their way
to the axial protoxylem. This type is important as affording an exception, in
the endarch structure of the xylem, to the usual exarch plan of the stelar
tissues. This species is the only one in which any indication of the
production of secondary xylem elements has so far been recorded.
Bruchmann[120] has shown that, in the small tuberous swelling which occurs
at the base of the young shoot (hypocotyl), a meristematic zone is formed
round the axial vascular strand and by its activity a few secondary tracheids
are added to the primary xylem. With this exception Selaginella appears to
have lost the power of secondary thickening, the possession of which
constitutes so striking a feature of the Palaeozoic Lycopods. Another type is
represented by S. inaequalifolia, an Indian species, the shoots of which may
have either a single stele or as many as five, each in its separate lacuna. The
homophyllous S. laevigata var. Lyallii Spr., a Madagascan species, affords a
further illustration of the variation in plan of the vascular tissues within the
cortex. The trabeculae consist in part of endodermal cells characterised by
cuticular bands. The cortex is usually differentiated into three fairly distinct
regions. Mechanical tissue of thick-walled fibres constitutes the outer
region (a); the middle cortex consists of thinner-walled parenchyma, the
elements of which become smaller and rather more compactly arranged in
the inner zone. The middle cortex is frequently characterised by the
presence of spaces and by the hyphal or trabecular structure of the tissue, a
feature which, as Bower[117] pointed out, is common to many recent and
fossil members of the Lycopodiales. In some cases, e.g. S. erythropus, from
tropical America, the cortex of the creeping stem consists entirely of thick-
walled cells. Selaginella grandis (fig. 130) has “a short decumbent stem
rooted at close intervals[118],” from which thick erect aerial shoots rise to a
height of one foot or more. In the apical region these erect axes give off
repeatedly forked foliage shoots on which the spiral phyllotaxis of the
homophyllous axis is gradually replaced by four rows of two kinds of
leaves (fig. 130, 2). The anatomy of this species agrees with that of S.
Martensii. The trailing or semi-erect and homophyllous shoots of
Selaginella spinosa[119] present a distinct type of vascular anatomy. The
upper part of the ascending stem has an axial strand of xylem with seven
peripheral groups of spiral protoxylem tracheae (fig. 131, B); in the trailing
portion of the shoot the protoxylem elements occur as one central group in
the solid rod of metaxylem through which the leaf-traces pass on their way
to the axial protoxylem. This type is important as affording an exception, in
the endarch structure of the xylem, to the usual exarch plan of the stelar
tissues. This species is the only one in which any indication of the
production of secondary xylem elements has so far been recorded.
Bruchmann[120] has shown that, in the small tuberous swelling which occurs
at the base of the young shoot (hypocotyl), a meristematic zone is formed
round the axial vascular strand and by its activity a few secondary tracheids
are added to the primary xylem. With this exception Selaginella appears to
have lost the power of secondary thickening, the possession of which
constitutes so striking a feature of the Palaeozoic Lycopods. Another type is
represented by S. inaequalifolia, an Indian species, the shoots of which may
have either a single stele or as many as five, each in its separate lacuna. The
homophyllous S. laevigata var. Lyallii Spr., a Madagascan species, affords a
further illustration of the variation in plan of the vascular tissues within the
Page 86
genus. There is a considerable difference in structure between the erect and
creeping shoots; in the former there may be as many as 12–13 steles, which
gradually coalesce before the vertical axis joins the creeping rhizome to
form one central and four peripheral steles. In the rhizome there is usually a
distinct axial stele without protoxylem, surrounded by an ill-defined lacuna
and enclosed by a cylindrical stele (solenostele)[121] usually two tracheae in
width with four protoxylem strands on its outer edge. The continuity of the
tubular stele is broken and, in transverse section, it assumes the form of a
horse-shoe close to the base of an erect shoot to which a crescentic vascular
strand is given off. Harvey-Gibson[122] has figured a section of the rhizome
of this type in which the axial vascular strand is represented by a slight
ridge of tracheae (fig. 131, C, t) projecting towards the centre of the axis of
the tubular stele. The cylindrical stele consists of xylem with external and
internal phloem (p): cuticularised endodermal cells occur at e and e.
Reference has already been made to the descending naked branches
given off from the points of ramification of the foliage shoots of
Selaginella. It has been shown by Harvey-Gibson[123] that these branches,
originally designated rhizophores by Nägeli and Leitgeb, as well as the
dichotomously branched roots which they produce below the level of the
ground, possess a single vascular strand of monarch type. It is interesting to
find that in some species the aerial portion of the rhizophore has a xylem
strand with a central protoxylem, an instance of endarch structure like that
in certain portions of the shoot-system of S. spinosa. The root-anatomy of
Selaginella and the dichotomous habit of branching afford points of
agreement with the subterranean organs of Lepidodendron and Sigillaria.
Leaves. The leaves of Selaginella[124] usually consist of a reticulum of
loosely arranged cells, but in some cases part of the mesophyll assumes the
palisade form. The single vascular bundle consists of a few small annular or
spiral tracheae and at the apex of the lamina the protoxylem elements are
accompanied by several short reticulated pitted elements. Both foliage
leaves and sporophylls are characterised by the possession of a ligule, a
structure which may present the appearance of a somewhat rectangular
plate (fig. 130, 4, l, and fig. 131, E–G, l) or assume a fan-shaped form with
a lobed or papillate margin. The base, composed of large cells, is sunk in
the tissue of the leaf close to its insertion on the stem (fig. 131, E, l) and
enclosed by a well-marked parenchymatous sheath. The sheath is separated
creeping shoots; in the former there may be as many as 12–13 steles, which
gradually coalesce before the vertical axis joins the creeping rhizome to
form one central and four peripheral steles. In the rhizome there is usually a
distinct axial stele without protoxylem, surrounded by an ill-defined lacuna
and enclosed by a cylindrical stele (solenostele)[121] usually two tracheae in
width with four protoxylem strands on its outer edge. The continuity of the
tubular stele is broken and, in transverse section, it assumes the form of a
horse-shoe close to the base of an erect shoot to which a crescentic vascular
strand is given off. Harvey-Gibson[122] has figured a section of the rhizome
of this type in which the axial vascular strand is represented by a slight
ridge of tracheae (fig. 131, C, t) projecting towards the centre of the axis of
the tubular stele. The cylindrical stele consists of xylem with external and
internal phloem (p): cuticularised endodermal cells occur at e and e.
Reference has already been made to the descending naked branches
given off from the points of ramification of the foliage shoots of
Selaginella. It has been shown by Harvey-Gibson[123] that these branches,
originally designated rhizophores by Nägeli and Leitgeb, as well as the
dichotomously branched roots which they produce below the level of the
ground, possess a single vascular strand of monarch type. It is interesting to
find that in some species the aerial portion of the rhizophore has a xylem
strand with a central protoxylem, an instance of endarch structure like that
in certain portions of the shoot-system of S. spinosa. The root-anatomy of
Selaginella and the dichotomous habit of branching afford points of
agreement with the subterranean organs of Lepidodendron and Sigillaria.
Leaves. The leaves of Selaginella[124] usually consist of a reticulum of
loosely arranged cells, but in some cases part of the mesophyll assumes the
palisade form. The single vascular bundle consists of a few small annular or
spiral tracheae and at the apex of the lamina the protoxylem elements are
accompanied by several short reticulated pitted elements. Both foliage
leaves and sporophylls are characterised by the possession of a ligule, a
structure which may present the appearance of a somewhat rectangular
plate (fig. 130, 4, l, and fig. 131, E–G, l) or assume a fan-shaped form with
a lobed or papillate margin. The base, composed of large cells, is sunk in
the tissue of the leaf close to its insertion on the stem (fig. 131, E, l) and
enclosed by a well-marked parenchymatous sheath. The sheath is separated
Page 87
from the vascular bundle of the leaf by one or more layers of cells, and in
some species these become transformed into short tracheids. The ligule is
regarded by Harvey-Gibson[125] as a specialised ramentum which serves the
temporary function of keeping moist the growing-point and young leaves.
Cones. The terminal portions of the branches of Selaginella usually bear
smaller leaves of uniform size which function as sporophylls, but in this
genus the fertile shoots do not generally form such distinct cones as in
many species of Lycopodium. In S. grandis (figs. 130, 3; 131, G) the long
and narrow strobili consist of a slender axis bearing imbricate sporophylls
in four rows: each sporophyll subtends a sporangium situated between the
ligule and the axis of the shoot. The sporangium may be developed from the
axis of the cone or, as in Lycopodium, from the cells of the sporophyll[126].
In some species the lower sporophylls bear only megasporangia, each
normally containing four megaspores, the microsporangia being confined to
the upper part of the cone. This distribution of the two kinds of sporangia is,
however, by no means constant[127]: in some cases, e.g. S. rupestris, cones
may bear megasporangia only, and in the cone of S. grandis, of which a
small piece is represented in fig. 131, G, all the sporangia were found to
contain microspores.
The occurrence of two kinds of spores in Selaginella constitutes a feature
of special importance from the point of view of the relationship between the
Phanerogams, in which heterospory is a constant character, and the
heterosporous Pteridophytes. One of the most striking distinctions between
the Phanerogams and the rest of the vegetable kingdom lies in the
production of seeds. Recent work has, however, shown that seed-production
can no longer be regarded as a distinguishing feature of the Gymnosperms
and Angiosperms. Palaeozoic plants which combined filicinean and
cycadean features resembled the existing Phanerogams in the possession of
highly specialised seeds. This discovery adds point to the comparison of the
true seed with structures concerned with reproduction in seedless plants,
which in the course of evolution gave rise to the more efficient arrangement
for the nursing, protection, and ultimate dispersal of the embryo. In the
megaspore of Selaginella we have, as Hofmeister was the first to recognise
in 1851, a structure homologous with the embryo-sac of the Phanerogam.
The embryo-sac consists of a large cell produced in a mass of
parenchymatous tissue known as the nucellus which is almost completely
some species these become transformed into short tracheids. The ligule is
regarded by Harvey-Gibson[125] as a specialised ramentum which serves the
temporary function of keeping moist the growing-point and young leaves.
Cones. The terminal portions of the branches of Selaginella usually bear
smaller leaves of uniform size which function as sporophylls, but in this
genus the fertile shoots do not generally form such distinct cones as in
many species of Lycopodium. In S. grandis (figs. 130, 3; 131, G) the long
and narrow strobili consist of a slender axis bearing imbricate sporophylls
in four rows: each sporophyll subtends a sporangium situated between the
ligule and the axis of the shoot. The sporangium may be developed from the
axis of the cone or, as in Lycopodium, from the cells of the sporophyll[126].
In some species the lower sporophylls bear only megasporangia, each
normally containing four megaspores, the microsporangia being confined to
the upper part of the cone. This distribution of the two kinds of sporangia is,
however, by no means constant[127]: in some cases, e.g. S. rupestris, cones
may bear megasporangia only, and in the cone of S. grandis, of which a
small piece is represented in fig. 131, G, all the sporangia were found to
contain microspores.
The occurrence of two kinds of spores in Selaginella constitutes a feature
of special importance from the point of view of the relationship between the
Phanerogams, in which heterospory is a constant character, and the
heterosporous Pteridophytes. One of the most striking distinctions between
the Phanerogams and the rest of the vegetable kingdom lies in the
production of seeds. Recent work has, however, shown that seed-production
can no longer be regarded as a distinguishing feature of the Gymnosperms
and Angiosperms. Palaeozoic plants which combined filicinean and
cycadean features resembled the existing Phanerogams in the possession of
highly specialised seeds. This discovery adds point to the comparison of the
true seed with structures concerned with reproduction in seedless plants,
which in the course of evolution gave rise to the more efficient arrangement
for the nursing, protection, and ultimate dispersal of the embryo. In the
megaspore of Selaginella we have, as Hofmeister was the first to recognise
in 1851, a structure homologous with the embryo-sac of the Phanerogam.
The embryo-sac consists of a large cell produced in a mass of
parenchymatous tissue known as the nucellus which is almost completely
Page 88
enclosed by one or more integuments. Fertilisation of the egg-cell within
the embryo-sac takes place as a rule while the female reproductive organ is
still attached to the parent-plant and separation does not occur until the
ovule has become the seed.
In a few cases, notably in certain plants characteristic of Mangrove
swamps, continuity between the seed and its parent is retained until after
germination. The megasporangium of Selaginella dehisces[128] along a line
marked out by the occurrence of smaller cells over the crest of the wall. It
has been customary to describe the megaspores as being fertilised after
ejection from the sporangia. This earlier separation from the parent and the
absence of any protective covering external to the spore-wall constitute two
distinguishing features between seeds and megaspores. In Selaginella apus,
a Californian species, Miss Lyon has shown that fertilisation of the egg-cell
usually takes place while the megaspore is still in the strobilus. On
examining withered decayed strobili of this species which had been
partially covered with the soil for some months after fertilisation of the
megaspores, several young plants were found with cotyledons and roots
projecting through the crevices of the megasporangia[129]. From this, adds
Miss Lyon, “it seems safe to assume that an embryo may have two periods
of growth separated by one of quiescence quite comparable to those of seed
plants with marked xerophilous features.”
In another Western American species S. rupestris described by the same
writer the cotyledons of young plants were found protruding from the
imbricate sporophylls of a withered cone (fig. 131, D). This species is
interesting also from the occasional occurrence of one instead of four
megasporangia in a sporangium; a condition which affords another
connecting link between the heterosporous Pteridophytes, on the one hand,
and the seed-bearing Phanerogams in which the occurrence of a single
embryo-sac (megaspore) in each ovule is the rule. The cones of Selaginella
rupestris retain connexion with the plant through the winter and fertilisation
occurs in the following spring. After the embryo has been formed the
megasporangium “becomes sunken in a shallow pit formed by the cushion-
like outgrowth of the sporophyll around the pedicel.” It is suggested that
this outgrowth may be comparable with the integument which grows up
from the sporophyll in the fossil genus Lepidocarpon[130] and almost
completely encloses the sporangium. In the drawings given by Miss Lyon
the embryo-sac takes place as a rule while the female reproductive organ is
still attached to the parent-plant and separation does not occur until the
ovule has become the seed.
In a few cases, notably in certain plants characteristic of Mangrove
swamps, continuity between the seed and its parent is retained until after
germination. The megasporangium of Selaginella dehisces[128] along a line
marked out by the occurrence of smaller cells over the crest of the wall. It
has been customary to describe the megaspores as being fertilised after
ejection from the sporangia. This earlier separation from the parent and the
absence of any protective covering external to the spore-wall constitute two
distinguishing features between seeds and megaspores. In Selaginella apus,
a Californian species, Miss Lyon has shown that fertilisation of the egg-cell
usually takes place while the megaspore is still in the strobilus. On
examining withered decayed strobili of this species which had been
partially covered with the soil for some months after fertilisation of the
megaspores, several young plants were found with cotyledons and roots
projecting through the crevices of the megasporangia[129]. From this, adds
Miss Lyon, “it seems safe to assume that an embryo may have two periods
of growth separated by one of quiescence quite comparable to those of seed
plants with marked xerophilous features.”
In another Western American species S. rupestris described by the same
writer the cotyledons of young plants were found protruding from the
imbricate sporophylls of a withered cone (fig. 131, D). This species is
interesting also from the occasional occurrence of one instead of four
megasporangia in a sporangium; a condition which affords another
connecting link between the heterosporous Pteridophytes, on the one hand,
and the seed-bearing Phanerogams in which the occurrence of a single
embryo-sac (megaspore) in each ovule is the rule. The cones of Selaginella
rupestris retain connexion with the plant through the winter and fertilisation
occurs in the following spring. After the embryo has been formed the
megasporangium “becomes sunken in a shallow pit formed by the cushion-
like outgrowth of the sporophyll around the pedicel.” It is suggested that
this outgrowth may be comparable with the integument which grows up
from the sporophyll in the fossil genus Lepidocarpon[130] and almost
completely encloses the sporangium. In the drawings given by Miss Lyon
Page 89
no features are recognisable which afford a parallel to the integument of
Lepidocarpon. I have, however, endeavoured to show, by a brief reference
to this author’s interesting account of the two Californian species, that the
physiological and morphological resemblances between the megasporangia
of Selaginella and the integumented ovules of the seed-bearing plants are
sufficiently close to enable us to recognise possible lines of advance
towards the development of the true seed.
Professor Campbell[131] records an additional example of a Selaginella—
probably S. Bigelovii—from the dry region of Southern California in which
the spores become completely dried up after the embryo has attained some
size, remaining in that state until the more favourable conditions succeeding
the dry season induce renewed activity.
Isoetaceae.
The genus Isoetes is peculiar among Pteridophytes both in habit and in
anatomical features. In its short and relatively thick tuberous stem,
terminating in a crowded rosette of subulate leaves like those of Juncus and
bearing numerous adventitious roots, Isoetes presents an appearance similar
to that of many monocotyledonous plants. The habit of the genus is well
represented by such species as Isoetes lacustris and I. echinospora[132] (fig.
132) both of which grow in freshwater lakes in Britain and in other north
European countries. The latter species bears leaves reaching a length of 18
cm. The resemblance in habit between this isolated member of the
Pteridophytes and certain Flowering plants, although in itself of no
morphological significance, is consistent with the view expressed by
Campbell that Isoetes may be directly related to the Monocotyledons[133].
Lepidocarpon. I have, however, endeavoured to show, by a brief reference
to this author’s interesting account of the two Californian species, that the
physiological and morphological resemblances between the megasporangia
of Selaginella and the integumented ovules of the seed-bearing plants are
sufficiently close to enable us to recognise possible lines of advance
towards the development of the true seed.
Professor Campbell[131] records an additional example of a Selaginella—
probably S. Bigelovii—from the dry region of Southern California in which
the spores become completely dried up after the embryo has attained some
size, remaining in that state until the more favourable conditions succeeding
the dry season induce renewed activity.
Isoetaceae.
The genus Isoetes is peculiar among Pteridophytes both in habit and in
anatomical features. In its short and relatively thick tuberous stem,
terminating in a crowded rosette of subulate leaves like those of Juncus and
bearing numerous adventitious roots, Isoetes presents an appearance similar
to that of many monocotyledonous plants. The habit of the genus is well
represented by such species as Isoetes lacustris and I. echinospora[132] (fig.
132) both of which grow in freshwater lakes in Britain and in other north
European countries. The latter species bears leaves reaching a length of 18
cm. The resemblance in habit between this isolated member of the
Pteridophytes and certain Flowering plants, although in itself of no
morphological significance, is consistent with the view expressed by
Campbell that Isoetes may be directly related to the Monocotyledons[133].
Page 90
Fig. 132. Isoetes echinospora (After Motelay and Vendryès).
A. Stem of I. lacustris.
B. Base of sporophyll: l, ligule; spg, sporangium partially covered by velum.
There is as a rule little or no difference between the foliage leaves and
sporophylls; in I. lacustris the latter are rather larger and in the terrestrial
species I. hystrix[134] the sterile leaves are represented by the expanded basal
portions only, which persist like the leaf-bases of Lepidodendron as dark
brown scales to form a protective investment to the older part of the stem.
The innermost leaves are usually sterile; next to these are sporophylls
bearing megasporangia, and on the outside are the older sporophylls with
A. Stem of I. lacustris.
B. Base of sporophyll: l, ligule; spg, sporangium partially covered by velum.
There is as a rule little or no difference between the foliage leaves and
sporophylls; in I. lacustris the latter are rather larger and in the terrestrial
species I. hystrix[134] the sterile leaves are represented by the expanded basal
portions only, which persist like the leaf-bases of Lepidodendron as dark
brown scales to form a protective investment to the older part of the stem.
The innermost leaves are usually sterile; next to these are sporophylls
bearing megasporangia, and on the outside are the older sporophylls with
Page 91
microsporangia. The long and slender portion of the leaf becomes suddenly
expanded close to its attachment to the stem into a broad base of crescentic
section which bears a fairly conspicuous ligule (figs. 132, B, l, 133, E, l)
inserted by a foot or glossopodium in a pit near the upper part of the
concave inner face. The ligule is usually larger than that of Selaginella,
though of the same type. The free awl-like lamina contains four large canals
bridged across at intervals by transverse diaphragms, and in the axial region
a single vascular bundle of collateral structure. Other vascular elements, in
the form of numerous short tracheids occur below the base of the
transversely elongated ligule.
Stomata are found on the leaves of I. hystrix, I. Boryana[135], and in other
species which are not permanently submerged. Both microsporangia and
megasporangia are characterised by their large size and by the presence of
trabeculae or strands of sterile tissue (fig. 133, E, H, t) completely bridging
across the sporangial cavity or extending as irregular ingrowths among the
spore-producing tissue. Similar sterile bands, though less abundant and
smaller, are occasionally met with in the still larger sporangia of
Lepidostrobus; these may be regarded as a further development of the
prominent pad of cells which projects into the sporangial cavity in recent
species of Lycopodium (fig. 126, D, p). The sporangia are attached by a
very short stalk to the base of a large depression in the leaf-base below the
ligule, from the pit of which they are separated by a ridge of tissue known
as the saddle, and from this ridge a veil of tissue (the velum) extends as a
roof over the sporangial chamber (fig. 133, E, v). In most species there is a
large gap between the lower edge of the velum and that of the sporangial
pit, but in I. hystrix this protective membrane is separated from the base of
the leaf by a narrow opening, the resemblance of which to the micropyle of
an ovule suggested to one of the older botanists the employment of the
same term[136]. Mr T. G. Hill[137] has called attention to the presence of
mucilage canals in the base of the sporophylls of I. hystrix, which he
compares with the strands of tissue known as the parichnos accompanying
the leaf-traces of Lepidodendron and Sigillaria in the outer cortex of the
stem. The transverse section shown in fig. 133, H and I, shows two of these
mucilage canals in an early stage of development; a strand of
parenchymatous elements distinguished by their partially disorganised
condition and more deeply stained membranes (fig. 133, I) runs through the
spandrels of the sporophyll tissue close to the upper surface. There is a
expanded close to its attachment to the stem into a broad base of crescentic
section which bears a fairly conspicuous ligule (figs. 132, B, l, 133, E, l)
inserted by a foot or glossopodium in a pit near the upper part of the
concave inner face. The ligule is usually larger than that of Selaginella,
though of the same type. The free awl-like lamina contains four large canals
bridged across at intervals by transverse diaphragms, and in the axial region
a single vascular bundle of collateral structure. Other vascular elements, in
the form of numerous short tracheids occur below the base of the
transversely elongated ligule.
Stomata are found on the leaves of I. hystrix, I. Boryana[135], and in other
species which are not permanently submerged. Both microsporangia and
megasporangia are characterised by their large size and by the presence of
trabeculae or strands of sterile tissue (fig. 133, E, H, t) completely bridging
across the sporangial cavity or extending as irregular ingrowths among the
spore-producing tissue. Similar sterile bands, though less abundant and
smaller, are occasionally met with in the still larger sporangia of
Lepidostrobus; these may be regarded as a further development of the
prominent pad of cells which projects into the sporangial cavity in recent
species of Lycopodium (fig. 126, D, p). The sporangia are attached by a
very short stalk to the base of a large depression in the leaf-base below the
ligule, from the pit of which they are separated by a ridge of tissue known
as the saddle, and from this ridge a veil of tissue (the velum) extends as a
roof over the sporangial chamber (fig. 133, E, v). In most species there is a
large gap between the lower edge of the velum and that of the sporangial
pit, but in I. hystrix this protective membrane is separated from the base of
the leaf by a narrow opening, the resemblance of which to the micropyle of
an ovule suggested to one of the older botanists the employment of the
same term[136]. Mr T. G. Hill[137] has called attention to the presence of
mucilage canals in the base of the sporophylls of I. hystrix, which he
compares with the strands of tissue known as the parichnos accompanying
the leaf-traces of Lepidodendron and Sigillaria in the outer cortex of the
stem. The transverse section shown in fig. 133, H and I, shows two of these
mucilage canals in an early stage of development; a strand of
parenchymatous elements distinguished by their partially disorganised
condition and more deeply stained membranes (fig. 133, I) runs through the
spandrels of the sporophyll tissue close to the upper surface. There is a
Page 92
close resemblance between the structure of these partially formed mucilage-
canals and the tissue which has been called the secretory zone in
Lepidodendron stems. Fig. 133, H, also shows a large microsporangium
with prominent trabeculae (t) lying below the velum. A longitudinal section
(fig. 133, E) through a sporophyll-base presents an appearance comparable
with that of an Araucarian cone-scale with its integumented ovule and
micropyle. The megaspores are characterised by ridges, spines, and other
surface-ornamentation[138]. Though usually unbranched, the perennial stem
of Isoetes (fig. 132) has in rare cases been found to exhibit dichotomous
branching, a feature, as Solms-Laubach[139] points out, consistent with a
Lycopodiaceous affinity. The apex is situated at the base of a funnel-shaped
depression. The stem is always grooved; in some species two and in others
three deep furrows extend from the base up the sides of the short and thick
axis towards the leaves: from the sides of these furrows numerous slender
roots are given off in acropetal succession. A stele of peculiar structure
occupies the centre of the stem; cylindrical in the upper part (fig. 133, A), it
assumes a narrow elliptical or, in species in which there are three furrows, a
triangular form in the lower portion of the tuberous stem.
ISOETES
The stem of I. lacustris represented in fig. 132, A, from which the
laminae of the leaves have been removed from the summit affords an
example of a species with two furrows. The drawing shows the widely
gaping sides of the broad furrow with circular root-scars and a few simple
and dichotomously branched roots. A short thick column of
parenchymatous tissue projects from a slightly eccentric position on the
base of the stem.
canals and the tissue which has been called the secretory zone in
Lepidodendron stems. Fig. 133, H, also shows a large microsporangium
with prominent trabeculae (t) lying below the velum. A longitudinal section
(fig. 133, E) through a sporophyll-base presents an appearance comparable
with that of an Araucarian cone-scale with its integumented ovule and
micropyle. The megaspores are characterised by ridges, spines, and other
surface-ornamentation[138]. Though usually unbranched, the perennial stem
of Isoetes (fig. 132) has in rare cases been found to exhibit dichotomous
branching, a feature, as Solms-Laubach[139] points out, consistent with a
Lycopodiaceous affinity. The apex is situated at the base of a funnel-shaped
depression. The stem is always grooved; in some species two and in others
three deep furrows extend from the base up the sides of the short and thick
axis towards the leaves: from the sides of these furrows numerous slender
roots are given off in acropetal succession. A stele of peculiar structure
occupies the centre of the stem; cylindrical in the upper part (fig. 133, A), it
assumes a narrow elliptical or, in species in which there are three furrows, a
triangular form in the lower portion of the tuberous stem.
ISOETES
The stem of I. lacustris represented in fig. 132, A, from which the
laminae of the leaves have been removed from the summit affords an
example of a species with two furrows. The drawing shows the widely
gaping sides of the broad furrow with circular root-scars and a few simple
and dichotomously branched roots. A short thick column of
parenchymatous tissue projects from a slightly eccentric position on the
base of the stem.
Page 93
Fig. 133. Isoetes lacustris.
A. Transverse section of stem: cr, cortex; x, x2 xylem; c, cambium; a, thin-walled
tissue; lt, leaf-traces; b, dead tissue.
B, C, D. Portions of A enlarged.
E. Longitudinal radial section of sporophyll-base: v, velum; l, ligule; bb; vascular
bundle; m, megaspores; t, sterile tissue.
F. Longitudinal section through the base of a root.
G. Transverse section of root.
H. Transverse section of sporophyll, showing sporangium with trabeculae, t; leaf-
trace, (lt), and two groups of secretory cells.
I. A group of secretory cells enlarged.
A. Transverse section of stem: cr, cortex; x, x2 xylem; c, cambium; a, thin-walled
tissue; lt, leaf-traces; b, dead tissue.
B, C, D. Portions of A enlarged.
E. Longitudinal radial section of sporophyll-base: v, velum; l, ligule; bb; vascular
bundle; m, megaspores; t, sterile tissue.
F. Longitudinal section through the base of a root.
G. Transverse section of root.
H. Transverse section of sporophyll, showing sporangium with trabeculae, t; leaf-
trace, (lt), and two groups of secretory cells.
I. A group of secretory cells enlarged.
Page 94
The primary vascular cylinder[140] consists of numerous spiral, annular or
reticulate tracheids (fig. 133, A, x) which are either isodiametric or longer in
a horizontal than in a vertical direction, associated with parenchyma. Lower
in the stem crushed and disorganised xylem elements are scattered through
a still living trabecular network of parenchymatous tissue. From the axial
cylinder numerous leaf-traces (fig. 133, A, lt) radiate outwards, at first in a
horizontal direction and then gradually ascending towards the leaves. The
vascular cylinder is of the type known as cauline; that is, some of the xylem
is distinct in origin from that which consists solely of the lower ends of
leaf-traces. As in Lycopodium the development of the metaxylem is
centripetal.
Von Mohl[141], and a few years later Hofmeister[142], were the first
botanists to give a satisfactory account of the anatomy of Isoetes but it is
only recently[143] that fresh light has been thrown upon the structural
features of the genus the interest of which is enhanced by the many points
of resemblance between the recent type and the Palaeozoic Lepidodendreae.
A striking anatomical feature is the power of the stem to produce secondary
vascular and non-vascular tissue; the genus is also characterised by the
early appearance of secondary meristematic activity which renders it
practically impossible to draw any distinct line between primary and
secondary growth. A cylinder of thin-walled tissue (fig. 133, A, a)
surrounds the primary central cylinder and in this a cambial zone, c, is
recognised even close to the stem-apex; this zone of dividing cells is
separated from the xylem by a few layers of rectangular cells to which the
term prismatic zone has been applied. The early appearance of the cambial
activity on the edge of the vascular cylinder is shown in fig. 133, C, which
represents part of a transverse section of a young stem. A leaf-trace, lt, is in
connexion with the primary xylem, x′, which consists of short tracheids,
often represented only by their spiral or reticulately thickened bands of
lignified wall, and scattered parenchyma. Some of the radially elongated
cells on the sides of the leaf-trace are seen to be in continuity on the outer
edge of the stele, at st, with flattened elements, some of which are sieve-
tubes. The position of a second leaf-trace is shown at lt′. External to the
sieve-tubes the tissue consists of radially arranged series of rectangular
cells, some of which have already assumed the function of a cambium (c).
The tissue produced by the cambium on its inner edge consists of a varying
reticulate tracheids (fig. 133, A, x) which are either isodiametric or longer in
a horizontal than in a vertical direction, associated with parenchyma. Lower
in the stem crushed and disorganised xylem elements are scattered through
a still living trabecular network of parenchymatous tissue. From the axial
cylinder numerous leaf-traces (fig. 133, A, lt) radiate outwards, at first in a
horizontal direction and then gradually ascending towards the leaves. The
vascular cylinder is of the type known as cauline; that is, some of the xylem
is distinct in origin from that which consists solely of the lower ends of
leaf-traces. As in Lycopodium the development of the metaxylem is
centripetal.
Von Mohl[141], and a few years later Hofmeister[142], were the first
botanists to give a satisfactory account of the anatomy of Isoetes but it is
only recently[143] that fresh light has been thrown upon the structural
features of the genus the interest of which is enhanced by the many points
of resemblance between the recent type and the Palaeozoic Lepidodendreae.
A striking anatomical feature is the power of the stem to produce secondary
vascular and non-vascular tissue; the genus is also characterised by the
early appearance of secondary meristematic activity which renders it
practically impossible to draw any distinct line between primary and
secondary growth. A cylinder of thin-walled tissue (fig. 133, A, a)
surrounds the primary central cylinder and in this a cambial zone, c, is
recognised even close to the stem-apex; this zone of dividing cells is
separated from the xylem by a few layers of rectangular cells to which the
term prismatic zone has been applied. The early appearance of the cambial
activity on the edge of the vascular cylinder is shown in fig. 133, C, which
represents part of a transverse section of a young stem. A leaf-trace, lt, is in
connexion with the primary xylem, x′, which consists of short tracheids,
often represented only by their spiral or reticulately thickened bands of
lignified wall, and scattered parenchyma. Some of the radially elongated
cells on the sides of the leaf-trace are seen to be in continuity on the outer
edge of the stele, at st, with flattened elements, some of which are sieve-
tubes. The position of a second leaf-trace is shown at lt′. External to the
sieve-tubes the tissue consists of radially arranged series of rectangular
cells, some of which have already assumed the function of a cambium (c).
The tissue produced by the cambium on its inner edge consists of a varying
Page 95
amount of secondary xylem composed of very short spiral tracheids; a few
of these may be lignified (fig. 133, A, x2) while others remain thin.
Phloem elements, recognisable by the presence of a thickened reticulum
enclosing small sieve-areas (fig 133, B, s) are fairly abundant, and for the
rest this intracambial region is composed of thin-walled parenchyma. In
longitudinal section these tissues present an appearance almost identical
with that observed in a transverse section. Fig. 133, B represents a
longitudinal section, through the intracambial zone and the edge of the
stele, of a younger stem than that shown in fig. 133, A. Most of the radially
disposed cells internal to the meristematic region are parenchymatous
without any distinctive features; a few scattered sieve-tubes (s) are
recognised by their elliptical sieve-areas and an occasional tracheid can be
detected. The cambium cuts off externally a succession of segments which
constitute additional cortical tissue (fig. 133, A, cr) of homogeneous
structure, composed of parenchymatous cells containing starch and rich in
intercellular spaces. As the stem grows in thickness the secondary cortex
reaches a considerable breadth and the superficial layers are from time to
time exfoliated as strips of dead and crushed tissue (fig. 133, A, b). The
diagrammatic sketch reproduced in fig. 133, A, serves to illustrate the
arrangement and relative size of the tissue-regions in an Isoetes stem. In the
centre occur numerous spirally or reticulate tracheae scattered in
parenchymatous tissue which has been considerably stretched and torn in
the peripheral region of the stele; the radiating lines mark the position of the
leaf-traces (lt) in the more horizontal part of their course. The zone between
the cambium (c) and the edge of the central cylinder consists of radially
disposed secondary tissue of short, and for the most part unlignified,
elements including sieve-tubes and parenchyma; the secondary xylem
elements consist largely of thin-walled rectangular cells with delicate spiral
bands, but discontinuous rows of lignified tracheae (x2) occur in certain
regions of the intracambial zone. The rest of the stem consists of secondary
cortex (cr) with patches of dead tissue (b) still adhering to the irregularly
furrowed surface. The structure of the cambium and its products is shown in
the detailed drawing reproduced in fig. 133, D. Many of the elements cut
off on the inner side of the cambium exhibit the characters of tracheids:
most of these are unlignified, but others have thicker and lignified walls
(tr).
of these may be lignified (fig. 133, A, x2) while others remain thin.
Phloem elements, recognisable by the presence of a thickened reticulum
enclosing small sieve-areas (fig 133, B, s) are fairly abundant, and for the
rest this intracambial region is composed of thin-walled parenchyma. In
longitudinal section these tissues present an appearance almost identical
with that observed in a transverse section. Fig. 133, B represents a
longitudinal section, through the intracambial zone and the edge of the
stele, of a younger stem than that shown in fig. 133, A. Most of the radially
disposed cells internal to the meristematic region are parenchymatous
without any distinctive features; a few scattered sieve-tubes (s) are
recognised by their elliptical sieve-areas and an occasional tracheid can be
detected. The cambium cuts off externally a succession of segments which
constitute additional cortical tissue (fig. 133, A, cr) of homogeneous
structure, composed of parenchymatous cells containing starch and rich in
intercellular spaces. As the stem grows in thickness the secondary cortex
reaches a considerable breadth and the superficial layers are from time to
time exfoliated as strips of dead and crushed tissue (fig. 133, A, b). The
diagrammatic sketch reproduced in fig. 133, A, serves to illustrate the
arrangement and relative size of the tissue-regions in an Isoetes stem. In the
centre occur numerous spirally or reticulate tracheae scattered in
parenchymatous tissue which has been considerably stretched and torn in
the peripheral region of the stele; the radiating lines mark the position of the
leaf-traces (lt) in the more horizontal part of their course. The zone between
the cambium (c) and the edge of the central cylinder consists of radially
disposed secondary tissue of short, and for the most part unlignified,
elements including sieve-tubes and parenchyma; the secondary xylem
elements consist largely of thin-walled rectangular cells with delicate spiral
bands, but discontinuous rows of lignified tracheae (x2) occur in certain
regions of the intracambial zone. The rest of the stem consists of secondary
cortex (cr) with patches of dead tissue (b) still adhering to the irregularly
furrowed surface. The structure of the cambium and its products is shown in
the detailed drawing reproduced in fig. 133, D. Many of the elements cut
off on the inner side of the cambium exhibit the characters of tracheids:
most of these are unlignified, but others have thicker and lignified walls
(tr).
Page 96
I. hystrix appears to be exceptional in retaining its leaf-bases, which form
a complete protective investment and prevent the exfoliation of dead cortex.
Each leaf-trace consists of a few spiral tracheids accompanied by narrow
phloem elements directly continuous with the secondary phloem of the
intracambial zone. Dr Scott and Mr Hill have pointed out that a normal
cambium is occasionally present in the stem of I. hystrix during the early
stages of growth; this gives rise to xylem internally. The few phloem
elements observed external to the cambium may be regarded as primary
phloem, a tissue not usually represented in an Isoetes stem[144]. The
occasional occurrence of this normal cambium, may, as Scott and Hill
suggest, be a survival from a former condition in which the secondary
thickening followed a less peculiar course. The lower leaf-traces become
more or less obliterated as the result of the constant increase in thickness of
the broad zone of secondary tissues through which they pass.
The adventitious roots are developed acropetally and arranged in parallel
series on each side of the median line of the two or three furrows. The three
arms of the triangular stele of I. hystrix and the two narrow ends of the long
axis of the stele of I. lacustris, which in transverse section has the form of a
flattened ellipse, are built up of successive root-bases. A root of Isoetes (fig.
133, G) possesses one vascular bundle, x, with a single strand of
protoxylem, px, thus agreeing in its monarch structure with the root-bundle
in Selaginella and many species of Lycopodium. The cortical region of the
root consists of a few layers of outer cortex succeeded by a large space,
formed by the breaking down of the inner cortical tissue, into which the
vascular bundle projects (fig. 133, F). The peculiarity of the roots in having
a hollow cortex and an eccentric vascular bundle was noticed by Von
Mohl[145]. In the monarch bundles, as in the fistular cortex and dichotomous
branching, the roots of Isoetes present a striking resemblance to the slender
rootlets of the Palaeozoic Stigmaria (see page 246). The longitudinal
section through the base of a root of Isoetes lacustris shown in fig. 133, F,
affords a further illustration of certain features common to the fossil and
recent types.
FOSSIL LYCOPODIALES.
Isoetaceae
a complete protective investment and prevent the exfoliation of dead cortex.
Each leaf-trace consists of a few spiral tracheids accompanied by narrow
phloem elements directly continuous with the secondary phloem of the
intracambial zone. Dr Scott and Mr Hill have pointed out that a normal
cambium is occasionally present in the stem of I. hystrix during the early
stages of growth; this gives rise to xylem internally. The few phloem
elements observed external to the cambium may be regarded as primary
phloem, a tissue not usually represented in an Isoetes stem[144]. The
occasional occurrence of this normal cambium, may, as Scott and Hill
suggest, be a survival from a former condition in which the secondary
thickening followed a less peculiar course. The lower leaf-traces become
more or less obliterated as the result of the constant increase in thickness of
the broad zone of secondary tissues through which they pass.
The adventitious roots are developed acropetally and arranged in parallel
series on each side of the median line of the two or three furrows. The three
arms of the triangular stele of I. hystrix and the two narrow ends of the long
axis of the stele of I. lacustris, which in transverse section has the form of a
flattened ellipse, are built up of successive root-bases. A root of Isoetes (fig.
133, G) possesses one vascular bundle, x, with a single strand of
protoxylem, px, thus agreeing in its monarch structure with the root-bundle
in Selaginella and many species of Lycopodium. The cortical region of the
root consists of a few layers of outer cortex succeeded by a large space,
formed by the breaking down of the inner cortical tissue, into which the
vascular bundle projects (fig. 133, F). The peculiarity of the roots in having
a hollow cortex and an eccentric vascular bundle was noticed by Von
Mohl[145]. In the monarch bundles, as in the fistular cortex and dichotomous
branching, the roots of Isoetes present a striking resemblance to the slender
rootlets of the Palaeozoic Stigmaria (see page 246). The longitudinal
section through the base of a root of Isoetes lacustris shown in fig. 133, F,
affords a further illustration of certain features common to the fossil and
recent types.
FOSSIL LYCOPODIALES.
Isoetaceae
Page 97
The geological history of this division of the Pteridophyta is exceedingly
meagre, a fact all the more regrettable as it is by no means improbable that
in the surviving genus Isoetes we have an isolated type possibly of
considerable antiquity and closely akin to such extinct genera as
Pleuromeia and Sigillaria. If Saporta’s Lower Cretaceous species Isoetes
Choffati[146], or more appropriately Isoetites Choffati, is correctly
determined, it is the oldest fossil member of the family and indeed the most
satisfactory among the more than doubtful species described as extinct
forms of Isoetes.
Isoetites.
The generic name Isoetites was first used by Münster[147] in the
description of a specimen, from the Jurassic lithographic slates of
Solenhofen in Bavaria, which he named Isoetites crociformis. The specific
name was chosen to express a resemblance of the tuberous appearance of
the lower part of the imperfectly preserved and indeterminable fossil to a
Crocus corm.
Impressions of Isoetes-like leaves from the Inferior Oolite of Yorkshire
figured by Phillips[148] and afterwards by Lindley[149] as Solenites Murrayana
were compared by the latter author with Isoetes and Pilularia, but these
leaves are now generally assigned to Heer’s gymnospermous genus
Czekanowskia. An examination of the structure of the epidermal cells of
these Jurassic impressions convinced me that they resemble recent
coniferous needles more closely than the leaves of any Pteridophyte. The
genus Czekanowskia[150] is recognised by several authors as a probable
member of the Ginkgoales.
Isoetites Choffati. Saporta.
The late Marquis of Saporta founded this species on two sets of
impressions from the Urgonian (Lower Cretaceous) of Portugal which,
though not found in actual organic connexion, may possibly be portions of
the same plant. Small relatively broad tuberous bodies reaching a breadth of
1 cm. are compared with the short and broad stem of Isoetes, which they
resemble in bearing numerous appendages radiating from the surface like
the roots of the recent species; on the exposed face of the stem occur
meagre, a fact all the more regrettable as it is by no means improbable that
in the surviving genus Isoetes we have an isolated type possibly of
considerable antiquity and closely akin to such extinct genera as
Pleuromeia and Sigillaria. If Saporta’s Lower Cretaceous species Isoetes
Choffati[146], or more appropriately Isoetites Choffati, is correctly
determined, it is the oldest fossil member of the family and indeed the most
satisfactory among the more than doubtful species described as extinct
forms of Isoetes.
Isoetites.
The generic name Isoetites was first used by Münster[147] in the
description of a specimen, from the Jurassic lithographic slates of
Solenhofen in Bavaria, which he named Isoetites crociformis. The specific
name was chosen to express a resemblance of the tuberous appearance of
the lower part of the imperfectly preserved and indeterminable fossil to a
Crocus corm.
Impressions of Isoetes-like leaves from the Inferior Oolite of Yorkshire
figured by Phillips[148] and afterwards by Lindley[149] as Solenites Murrayana
were compared by the latter author with Isoetes and Pilularia, but these
leaves are now generally assigned to Heer’s gymnospermous genus
Czekanowskia. An examination of the structure of the epidermal cells of
these Jurassic impressions convinced me that they resemble recent
coniferous needles more closely than the leaves of any Pteridophyte. The
genus Czekanowskia[150] is recognised by several authors as a probable
member of the Ginkgoales.
Isoetites Choffati. Saporta.
The late Marquis of Saporta founded this species on two sets of
impressions from the Urgonian (Lower Cretaceous) of Portugal which,
though not found in actual organic connexion, may possibly be portions of
the same plant. Small relatively broad tuberous bodies reaching a breadth of
1 cm. are compared with the short and broad stem of Isoetes, which they
resemble in bearing numerous appendages radiating from the surface like
the roots of the recent species; on the exposed face of the stem occur
Page 98
scattered circular scars representing the position of roots which were
detached before fossilisation. Other impressions are identified as the basal
portions of sporophylls bearing sporangia: these suggest the expanded base
of the fertile leaves of Isoetes with vertically elongated sporangia, some of
which have a smooth surface while in others traces of internal structure are
exposed; the interior consists of an irregular network with depressions
containing carbonised remains of spores.
While recognising a general resemblance to the sporophylls of Isoetes,
certain differences are obvious: there is no ligule in the fossil leaves nor are
there any distinct traces of vascular strands such as occur in the leaves of
recent species. The form of the sporangium, more elongated than in the
majority of recent forms, is compared by Saporta with that in a south
European species Isoetes setacea Spr.
Such evidence as we have lends support to the inclusion of these
Portuguese fossils in the genus Isoetites, but apart from the fact that we
have no proof of any connexion between the stems and supposed
sporophylls, the resemblance of the latter to those of Isoetes is, perhaps,
hardly sufficient to satisfy all reasonable scepticism.
The generic name Isoetopsis was used by Saporta as more appropriate
than Isoetes for some Eocene fossils from Aix-en-Provence which are too
doubtful to rank as trustworthy evidence of the existence of the recent
genus. The species, Isoetopsis subaphylla[151] is founded on impressions of
small scales, 4 mm. long, bearing circular bodies which are compared with
sporangia or spores.
Other records of fossils referred to Isoetes need not be described as they
have no claim to be regarded as contributions towards the past history of the
genus. Heer’s Miocene species Isoetites Scheuzeri and I. Braunii Unger[152]
from Switzerland are based on unsatisfactory material and are of no
importance.
Pleuromeia.
The generic name Pleuromeia, was suggested by Corda[153] for a fossil
from the Bunter Sandstone, the original description of which was based by
detached before fossilisation. Other impressions are identified as the basal
portions of sporophylls bearing sporangia: these suggest the expanded base
of the fertile leaves of Isoetes with vertically elongated sporangia, some of
which have a smooth surface while in others traces of internal structure are
exposed; the interior consists of an irregular network with depressions
containing carbonised remains of spores.
While recognising a general resemblance to the sporophylls of Isoetes,
certain differences are obvious: there is no ligule in the fossil leaves nor are
there any distinct traces of vascular strands such as occur in the leaves of
recent species. The form of the sporangium, more elongated than in the
majority of recent forms, is compared by Saporta with that in a south
European species Isoetes setacea Spr.
Such evidence as we have lends support to the inclusion of these
Portuguese fossils in the genus Isoetites, but apart from the fact that we
have no proof of any connexion between the stems and supposed
sporophylls, the resemblance of the latter to those of Isoetes is, perhaps,
hardly sufficient to satisfy all reasonable scepticism.
The generic name Isoetopsis was used by Saporta as more appropriate
than Isoetes for some Eocene fossils from Aix-en-Provence which are too
doubtful to rank as trustworthy evidence of the existence of the recent
genus. The species, Isoetopsis subaphylla[151] is founded on impressions of
small scales, 4 mm. long, bearing circular bodies which are compared with
sporangia or spores.
Other records of fossils referred to Isoetes need not be described as they
have no claim to be regarded as contributions towards the past history of the
genus. Heer’s Miocene species Isoetites Scheuzeri and I. Braunii Unger[152]
from Switzerland are based on unsatisfactory material and are of no
importance.
Pleuromeia.
The generic name Pleuromeia, was suggested by Corda[153] for a fossil
from the Bunter Sandstone, the original description of which was based by
Page 99
Münster[154] on a specimen discovered in a split stone from the tower of
Magdeburg Cathedral.
The majority of the specimens have been obtained from the
neighbourhood of Bernburg, but a few examples are recorded from
Commern and other German localities: all are now included under the name
Pleuromeia Sternbergi. Germar, who published one of the earlier accounts
of the species, states that Corda dissented from Münster’s choice of the
name Sigillaria and proposed the new generic title Pleuromeia. One of the
best descriptions of the genus we owe to Solms-Laubach[155] whose paper
contains references to earlier writers. Illustrations have been published by
Münster, Germar[156], Bischof[157], Solms-Laubach and Potonié[158].
Pleuromeia Sternbergi. (Münster.)
Fig. 134.
1842. Sigillaria Sternbergii, Münster.
1854. Sagenaria Bischofii, Goeppert[159].
1885. Sigillaria oculina, Blanckenhorn.
1904. Pleuromeia oculina, Potonié.
Pleuromeia Sternbergi is represented by casts of vegetative and fertile
axes, but the preservation of the latter is not sufficiently good to enable us
to draw any very definite conclusions as to the nature of the reproductive
organs. Casts of the stems reach a length of about 1 metre and a diameter of
5–6 cm., or in some cases 10 cm.; all of them are in a more or less
decorticated state, the degree of decortication being responsible for
differences in the external features which led Spieker[160] to adopt more than
one specific name.
Fig. 134, A, represents a sketch, made some years ago, of a specimen in
the Breslau Museum which contains several examples of this species,
among others those described by Germar in 1852. The cylindrical cast (38
cm. long by 12 cm. in circumference), which has been slightly squeezed
towards the upper end, bears spirally arranged imperfectly preserved leaf-
scars and the lower end shows the truncated base of one of the short
Stigmaria-like arms characteristic of the plant. As shown clearly in a
specimen originally figured by Bischof and more recently by Potonié[161],
Magdeburg Cathedral.
The majority of the specimens have been obtained from the
neighbourhood of Bernburg, but a few examples are recorded from
Commern and other German localities: all are now included under the name
Pleuromeia Sternbergi. Germar, who published one of the earlier accounts
of the species, states that Corda dissented from Münster’s choice of the
name Sigillaria and proposed the new generic title Pleuromeia. One of the
best descriptions of the genus we owe to Solms-Laubach[155] whose paper
contains references to earlier writers. Illustrations have been published by
Münster, Germar[156], Bischof[157], Solms-Laubach and Potonié[158].
Pleuromeia Sternbergi. (Münster.)
Fig. 134.
1842. Sigillaria Sternbergii, Münster.
1854. Sagenaria Bischofii, Goeppert[159].
1885. Sigillaria oculina, Blanckenhorn.
1904. Pleuromeia oculina, Potonié.
Pleuromeia Sternbergi is represented by casts of vegetative and fertile
axes, but the preservation of the latter is not sufficiently good to enable us
to draw any very definite conclusions as to the nature of the reproductive
organs. Casts of the stems reach a length of about 1 metre and a diameter of
5–6 cm., or in some cases 10 cm.; all of them are in a more or less
decorticated state, the degree of decortication being responsible for
differences in the external features which led Spieker[160] to adopt more than
one specific name.
Fig. 134, A, represents a sketch, made some years ago, of a specimen in
the Breslau Museum which contains several examples of this species,
among others those described by Germar in 1852. The cylindrical cast (38
cm. long by 12 cm. in circumference), which has been slightly squeezed
towards the upper end, bears spirally arranged imperfectly preserved leaf-
scars and the lower end shows the truncated base of one of the short
Stigmaria-like arms characteristic of the plant. As shown clearly in a
specimen originally figured by Bischof and more recently by Potonié[161],
Page 100
the stem-base is divided by a double dichotomy into four short and broad
lobes with blunt apices and bent upwards like the arms of a grappling iron
(fig. 134, D). The surface of this basal region is characterised by numerous
circular scars (fig. 134, D; 4 scars enlarged) in the form of slightly
projecting areas with a depression in the centre of each. These are
undoubtedly the scars of rootlets, remains of which are occasionally seen
radiating through the surrounding rock. As seen in fig. 134, D, a, the
fractured surface of a basal area may reveal the existence of an axial
vascular cylinder giving off slender branches to the rootlets.
lobes with blunt apices and bent upwards like the arms of a grappling iron
(fig. 134, D). The surface of this basal region is characterised by numerous
circular scars (fig. 134, D; 4 scars enlarged) in the form of slightly
projecting areas with a depression in the centre of each. These are
undoubtedly the scars of rootlets, remains of which are occasionally seen
radiating through the surrounding rock. As seen in fig. 134, D, a, the
fractured surface of a basal area may reveal the existence of an axial
vascular cylinder giving off slender branches to the rootlets.
Page 101
Fig. 134. Pleuromeia Sternbergi.
A. Cast of stem in the Breslau Museum (⅓ nat. size). (A.C.S.)
B. “Sigillaria oculina” Blanckenhorn. (After Weiss).
C, D. Leaf-scars and base of stem: a, vascular tissue. (After Solms-Laubach.)
The bulbous enlargement at the base of the Brown seaweed Laminaria
bulbosa Lam.[162] simulates the swollen base of Pleuromeia; but a confusion
between these two plants is hardly likely to occur. Above the Stigmaria-like
base the gradually tapered axis, in the less decorticated specimens, bears
spirally disposed transversely elongated areas consisting of two triangular
scars between which is the point of exit of a leaf-trace. The form of the leaf-
A. Cast of stem in the Breslau Museum (⅓ nat. size). (A.C.S.)
B. “Sigillaria oculina” Blanckenhorn. (After Weiss).
C, D. Leaf-scars and base of stem: a, vascular tissue. (After Solms-Laubach.)
The bulbous enlargement at the base of the Brown seaweed Laminaria
bulbosa Lam.[162] simulates the swollen base of Pleuromeia; but a confusion
between these two plants is hardly likely to occur. Above the Stigmaria-like
base the gradually tapered axis, in the less decorticated specimens, bears
spirally disposed transversely elongated areas consisting of two triangular
scars between which is the point of exit of a leaf-trace. The form of the leaf-
Page 102
scars is best seen on the face of a mould figured by Solms-Laubach (fig.
134, C): in this case the two triangular areas appear as slight projections
separated by a narrow groove marking the position of the vascular bundle
of the leaf. The curved lines above and below the leaf-scar probably mark
the boundary of the leaf-base. The two triangular scars are compared by
Solms-Laubach and by Potonié with the parichnos-scars of Sigillaria and
Lepidodendron (cf. fig. 146, C), but the large size of the Pleuromeia scars
constitutes an obvious difference though possibly not a distinction of
importance.
The occurrence of a vertical canal filled with carbonaceous material in
some of the stems throws light on the internal structure: the canal, which is
described by Solms-Laubach as having a stellate outline in transverse
section recalls the narrow central cylinder of a Lepidodendron stem, and
this comparison is strengthened by the presence of obliquely ascending
grooves which represent leaf-traces passing through the cortex. In
specimens which have lost more of the cortical tissues the surface is
characterised by spirally disposed, discontinuous vertical grooves
representing portions of leaf-traces precisely as they appear in similar casts
of Lepidodendron. There is no direct evidence of the existence of secondary
wood in the stem, but, as Potonié has pointed out, the greater transverse
elongation of the leaf-scars in the lower part of a cast (fig. 134, A) points to
the production of some secondary tissue either in the vascular cylinder or
cortex, or possibly in both regions.
In some specimens of Pleuromeia the upper portion is clothed with
crowded and imbricate sporophylls which reach a length of 2·5 cm., a
maximum breadth of 2·7 cm., and a thickness of 1 mm. Each sporophyll
has a thin wing-like border, and on the lower face are several parallel lines.
Solms-Laubach describes the sporangium or ovule as attached to the lower
surface of the sporophyll and this opinion has been confirmed by Fitting[163]
who has also brought forward satisfactory evidence in favour of the
sporangial nature of the reproductive organs. Fitting found numerous spores
in the Bunter Sandstone near Halle; these are flattened circular bodies 0·5–
0·7 mm. in diameter with a granulated surface and the three converging
lines characteristic of spores produced in tetrads. The comparison made by
this author between the sporophylls of Pleuromeia, which bore the
sporangia on the lower surface instead of on the upper as in other
134, C): in this case the two triangular areas appear as slight projections
separated by a narrow groove marking the position of the vascular bundle
of the leaf. The curved lines above and below the leaf-scar probably mark
the boundary of the leaf-base. The two triangular scars are compared by
Solms-Laubach and by Potonié with the parichnos-scars of Sigillaria and
Lepidodendron (cf. fig. 146, C), but the large size of the Pleuromeia scars
constitutes an obvious difference though possibly not a distinction of
importance.
The occurrence of a vertical canal filled with carbonaceous material in
some of the stems throws light on the internal structure: the canal, which is
described by Solms-Laubach as having a stellate outline in transverse
section recalls the narrow central cylinder of a Lepidodendron stem, and
this comparison is strengthened by the presence of obliquely ascending
grooves which represent leaf-traces passing through the cortex. In
specimens which have lost more of the cortical tissues the surface is
characterised by spirally disposed, discontinuous vertical grooves
representing portions of leaf-traces precisely as they appear in similar casts
of Lepidodendron. There is no direct evidence of the existence of secondary
wood in the stem, but, as Potonié has pointed out, the greater transverse
elongation of the leaf-scars in the lower part of a cast (fig. 134, A) points to
the production of some secondary tissue either in the vascular cylinder or
cortex, or possibly in both regions.
In some specimens of Pleuromeia the upper portion is clothed with
crowded and imbricate sporophylls which reach a length of 2·5 cm., a
maximum breadth of 2·7 cm., and a thickness of 1 mm. Each sporophyll
has a thin wing-like border, and on the lower face are several parallel lines.
Solms-Laubach describes the sporangium or ovule as attached to the lower
surface of the sporophyll and this opinion has been confirmed by Fitting[163]
who has also brought forward satisfactory evidence in favour of the
sporangial nature of the reproductive organs. Fitting found numerous spores
in the Bunter Sandstone near Halle; these are flattened circular bodies 0·5–
0·7 mm. in diameter with a granulated surface and the three converging
lines characteristic of spores produced in tetrads. The comparison made by
this author between the sporophylls of Pleuromeia, which bore the
sporangia on the lower surface instead of on the upper as in other
Page 103
lycopodiaceous plants, and the pollen-sacs of Conifers, is worthy of note in
reference to the possible relationship between Conifers and Lycopods.
A comparison of the Isoetes stem represented in fig. 132, A, with the base
of a Pleuromeia shows a striking similarity, but, as Fitting points out, the
Stigmaria-like arms of the fossil contained a vascular cylinder whereas the
blunt lobes of Isoetes consist exclusively of cortical tissue, the roots being
given off from the grooves between the lobes of the tuberous stem.
The position of Pleuromeia must for the present be left an open question;
it is, however, clear that the plant bears a close resemblance in the form of
its base to the Stigmarian branches of Lepidodendron and Sigillaria. The
vegetative shoot appears to be constructed on a plan similar to that of these
two Palaeozoic genera, but the strobilus is of a different type. It would seem
probable that Pleuromeia may be closely allied to Isoetes and to the
arborescent Lycopods of Palaeozoic floras. It is not improbably a link in a
chain of types which includes Sigillaria on the one hand and Isoetes on the
other.
It is not improbable that a specimen from the Lower Bunter of Commern
which Blanckenhorn made the type of a new species, Sigillaria oculina (fig.
134, B) is specifically identical with Pleuromeia Sternbergi. An
examination of a cast of the type-specimen in the Berlin Bergakademie led
me to regard the fossil with some hesitation as a true Sigillaria, but a more
extended knowledge of Pleuromeia lends support to the view adopted by
Potonié[164] that Blanckenhorn’s plant is not genetically distinct from
Pleuromeia Sternbergi. The resemblance between Sigillaria oculina and
some of the Palaeozoic species of Sigillaria emphasised by Weiss[165] has
given rise to the belief that the genus Sigillaria persisted into the Triassic
era; it is, however, highly probable that the Bunter specimen has no claim to
the generic name under which it has hither to been known.
The Bunter Sandstone in which Pleuromeia is the sole representative of
plant-life, at least in certain localities, is usually considered to be a desert
formation. We may not be far wrong in accepting Fitting’s suggestion that
in this isolated species we have a relic of the sparse vegetation which was
able to exist where the presence of lakes added a touch of life to the
deadness of the Triassic desert.
reference to the possible relationship between Conifers and Lycopods.
A comparison of the Isoetes stem represented in fig. 132, A, with the base
of a Pleuromeia shows a striking similarity, but, as Fitting points out, the
Stigmaria-like arms of the fossil contained a vascular cylinder whereas the
blunt lobes of Isoetes consist exclusively of cortical tissue, the roots being
given off from the grooves between the lobes of the tuberous stem.
The position of Pleuromeia must for the present be left an open question;
it is, however, clear that the plant bears a close resemblance in the form of
its base to the Stigmarian branches of Lepidodendron and Sigillaria. The
vegetative shoot appears to be constructed on a plan similar to that of these
two Palaeozoic genera, but the strobilus is of a different type. It would seem
probable that Pleuromeia may be closely allied to Isoetes and to the
arborescent Lycopods of Palaeozoic floras. It is not improbably a link in a
chain of types which includes Sigillaria on the one hand and Isoetes on the
other.
It is not improbable that a specimen from the Lower Bunter of Commern
which Blanckenhorn made the type of a new species, Sigillaria oculina (fig.
134, B) is specifically identical with Pleuromeia Sternbergi. An
examination of a cast of the type-specimen in the Berlin Bergakademie led
me to regard the fossil with some hesitation as a true Sigillaria, but a more
extended knowledge of Pleuromeia lends support to the view adopted by
Potonié[164] that Blanckenhorn’s plant is not genetically distinct from
Pleuromeia Sternbergi. The resemblance between Sigillaria oculina and
some of the Palaeozoic species of Sigillaria emphasised by Weiss[165] has
given rise to the belief that the genus Sigillaria persisted into the Triassic
era; it is, however, highly probable that the Bunter specimen has no claim to
the generic name under which it has hither to been known.
The Bunter Sandstone in which Pleuromeia is the sole representative of
plant-life, at least in certain localities, is usually considered to be a desert
formation. We may not be far wrong in accepting Fitting’s suggestion that
in this isolated species we have a relic of the sparse vegetation which was
able to exist where the presence of lakes added a touch of life to the
deadness of the Triassic desert.
Page 104
Pleuromeia is recorded by Fliche as a rare fossil in the Middle Trias of
France in the neighbourhood of Lunéville[166].
Herbaceous fossil species of Lycopodiales.
The history of our knowledge of fossil representatives of the
Lycopodiales, as also of the Equisetales, affords a striking illustration of the
danger of attempting to found a classification on such differences as are
expressed by the terms herbaceous and arborescent in the sense in which
they are usually employed. As we have seen[167], the presence of secondary
wood in stems of the Palaeozoic plant now known as Calamites led so
competent a botanist as Adolphe Brongniart to recognise a distinct generic
type Calamodendron, which he placed in the Gymnosperms, reserving the
designation Calamities for species in which no indication of secondary
thickening had been found.
Similarly, the genus Sigillaria was regarded as a Gymnosperm because it
was believed to be distinguished from Lepidodendron by the power of
forming secondary vascular tissues; the latter genus, originally thought to
be always herbaceous, was classed with the Pteridophytes. At the time when
this unnatural separation was made between stems with secondary wood
and those in which no secondary wood was known to exist, botanists were
not aware of the occurrence of any recent Pteridophyte which shared with
the higher plants the power of secondary growth in thickness provided by
means of a meristematic zone. It is true that the presence or absence of a
cambium does not in practice always coincide with the division into
herbaceous and arborescent plants: no one would speak of a Date-Palm as a
herbaceous plant despite the absence of secondary wood.
The danger which should be borne in mind, in adopting as a matter of
convenience the term herbaceous as a sectional heading, is that it should not
be taken to imply a complete inability of the so-called herbaceous types to
make secondary additions to their conducting tissues. The specimens on
which the species of Lycopodites and Selaginellites, (genera which may be
designated herbaceous,) are founded are preserved as impressions and not
as petrifications; we can, therefore, base definitions only on habit and on
such features as are shown by fertile leaves and sporangia. We are fully
justified in concluding from evidence adduced by Goldenberg more than
France in the neighbourhood of Lunéville[166].
Herbaceous fossil species of Lycopodiales.
The history of our knowledge of fossil representatives of the
Lycopodiales, as also of the Equisetales, affords a striking illustration of the
danger of attempting to found a classification on such differences as are
expressed by the terms herbaceous and arborescent in the sense in which
they are usually employed. As we have seen[167], the presence of secondary
wood in stems of the Palaeozoic plant now known as Calamites led so
competent a botanist as Adolphe Brongniart to recognise a distinct generic
type Calamodendron, which he placed in the Gymnosperms, reserving the
designation Calamities for species in which no indication of secondary
thickening had been found.
Similarly, the genus Sigillaria was regarded as a Gymnosperm because it
was believed to be distinguished from Lepidodendron by the power of
forming secondary vascular tissues; the latter genus, originally thought to
be always herbaceous, was classed with the Pteridophytes. At the time when
this unnatural separation was made between stems with secondary wood
and those in which no secondary wood was known to exist, botanists were
not aware of the occurrence of any recent Pteridophyte which shared with
the higher plants the power of secondary growth in thickness provided by
means of a meristematic zone. It is true that the presence or absence of a
cambium does not in practice always coincide with the division into
herbaceous and arborescent plants: no one would speak of a Date-Palm as a
herbaceous plant despite the absence of secondary wood.
The danger which should be borne in mind, in adopting as a matter of
convenience the term herbaceous as a sectional heading, is that it should not
be taken to imply a complete inability of the so-called herbaceous types to
make secondary additions to their conducting tissues. The specimens on
which the species of Lycopodites and Selaginellites, (genera which may be
designated herbaceous,) are founded are preserved as impressions and not
as petrifications; we can, therefore, base definitions only on habit and on
such features as are shown by fertile leaves and sporangia. We are fully
justified in concluding from evidence adduced by Goldenberg more than
Page 105
fifty years ago and from similar evidence brought to light by more recent
researches, that there existed in the Palaeozoic era lycopodiaceous species
in close agreement in their herbaceous habit with the lycopods of present-
day floras. It has been suggested[168] that the direct ancestors of the genera
Lycopodium and Selaginella are represented by the species of Lycopodites
and Selaginellites rather than by Lepidodendron and Sigillaria, the
arborescent habit of which has been rendered familiar by the numerous
attempts to furnish pictorial reproductions of a Palaeozoic forest. Until we
are able to subject the species classed as herbaceous to microscopical
examination we cannot make any positive statement as to the correctness of
this view, but such facts as we possess lead us to regard the suggestion as
resting on a sound basis.
Palaeobotanical literature abounds in records of species of Lycopodites,
Lycopodium, Selaginella and Selaginites, which have been so named in the
belief that their vegetative shoots bear a greater resemblance to those of
recent lycopodiaceous plants than to the foliage shoots of Lepidodendron.
Many of these records are valueless: Lepidodendra, twigs of
Bothrodendron[169] species of conifers, fern rhizomes, and Aphlebiae[170]
have masqueraded as herbaceous lycopods. It is obvious that an attempt to
identify fossils presenting a general agreement in habit and leaf-form with
recent species of lycopods must be attended with considerable risk of error.
Recent Conifers include several species the smaller branches of which
simulate the leafy shoots of certain species of Lycopodium and Selaginella,
and it is not surprising to find that this similarity has been responsible for
many false determinations. Among Mosses and the larger foliose
Liverworts there are species which in the condition of imperfectly
preserved impressions, might easily be mistaken for lycopodiaceous shoots:
an equally close resemblance is apparent in the case of some flowering
plants, such as New Zealand species of Veronica, Tafalla graveolens (a
Composite), Lavoisiera lycopodiodes Gard.[171] (a species of
Melastomaceae), all of which have the habit of Cupressineae among the
conifers as well as of certain lycopodiaceous plants. It may be impossible to
decide whether fossil impressions of branches, which are presumably
lycopodiaceous, bear two kinds of leaves[172] like the great majority of
recent species of Selaginella. Selaginella grandis, if seen from the under
surface, would appear to have two rows of leaves only and might be
researches, that there existed in the Palaeozoic era lycopodiaceous species
in close agreement in their herbaceous habit with the lycopods of present-
day floras. It has been suggested[168] that the direct ancestors of the genera
Lycopodium and Selaginella are represented by the species of Lycopodites
and Selaginellites rather than by Lepidodendron and Sigillaria, the
arborescent habit of which has been rendered familiar by the numerous
attempts to furnish pictorial reproductions of a Palaeozoic forest. Until we
are able to subject the species classed as herbaceous to microscopical
examination we cannot make any positive statement as to the correctness of
this view, but such facts as we possess lead us to regard the suggestion as
resting on a sound basis.
Palaeobotanical literature abounds in records of species of Lycopodites,
Lycopodium, Selaginella and Selaginites, which have been so named in the
belief that their vegetative shoots bear a greater resemblance to those of
recent lycopodiaceous plants than to the foliage shoots of Lepidodendron.
Many of these records are valueless: Lepidodendra, twigs of
Bothrodendron[169] species of conifers, fern rhizomes, and Aphlebiae[170]
have masqueraded as herbaceous lycopods. It is obvious that an attempt to
identify fossils presenting a general agreement in habit and leaf-form with
recent species of lycopods must be attended with considerable risk of error.
Recent Conifers include several species the smaller branches of which
simulate the leafy shoots of certain species of Lycopodium and Selaginella,
and it is not surprising to find that this similarity has been responsible for
many false determinations. Among Mosses and the larger foliose
Liverworts there are species which in the condition of imperfectly
preserved impressions, might easily be mistaken for lycopodiaceous shoots:
an equally close resemblance is apparent in the case of some flowering
plants, such as New Zealand species of Veronica, Tafalla graveolens (a
Composite), Lavoisiera lycopodiodes Gard.[171] (a species of
Melastomaceae), all of which have the habit of Cupressineae among the
conifers as well as of certain lycopodiaceous plants. It may be impossible to
decide whether fossil impressions of branches, which are presumably
lycopodiaceous, bear two kinds of leaves[172] like the great majority of
recent species of Selaginella. Selaginella grandis, if seen from the under
surface, would appear to have two rows of leaves only and might be
Page 106
confused with a small twig of such a conifer as Dacrydium Kirkii, a New
Zealand species.
The New Zealand conifers Dacrydium cupressinum Soland. and
Podocarpus dacrydioides Rich. closely simulate species of Selaginellites
and Lycopodites: in the British Museum a specimen of the latter species
bears a label describing it as Lycopodium arboreum (Sir Joseph Hooker and
Dr Solander; 1769). The twigs of the Tasmanian conifer Microcachyrs
tetragona Hook. f. are very similar in habit to shoots of the recent
Lycopodium tetragonum (fig. 121, C).
In the description of examples of Lycopodites and Selaginellites I have
confined myself to such as appear to be above suspicion either because of
the presence of spore-bearing organs or, in a few cases, because the
specimens of sterile shoots are sufficiently large to show the form of
branching in addition to the texture of the leaves. The two generic names
Lycopodites and Selaginellites are employed for fossil species which there
are substantial grounds for regarding as representatives of Lycopodium and
Selaginella. The designation Selaginellites is adopted only for species
which afford evidence of heterospory; the name Lycopodites, on the other
hand, is used in a comprehensive sense to include all forms—whether
homophyllous or heterophyllous—which are not known to be
heterosporous. This restricted use of the generic name Selaginellites is
advocated by Zeiller[173], who instituted the genus, and by Halle[174] in his
recent paper on herbaceous lycopods.
Lycopodites.
The generic term Lycopodites was used by Brongniart in 1822[175] in
describing some Tertiary examples of slender axes clothed with small scale-
like leaves which he named Lycopodites squamatus. These are fragments of
coniferous shoots. In the Prodrome d’une histoire des végétaux fossiles[176]
Brongniart included several Palaeozoic and Jurassic species in Lycopodites
and instituted a new genus Selaginites, expressing a doubt as to the wisdom
of attempting to draw a generic distinction between the two sets of species.
In a later work[177] he recognised only one undoubted species, Lycopodites
falcatus. The first satisfactory account of fossils referred to Lycopodites is
by Goldenberg[178] who gave the following definition of the genus:
Zealand species.
The New Zealand conifers Dacrydium cupressinum Soland. and
Podocarpus dacrydioides Rich. closely simulate species of Selaginellites
and Lycopodites: in the British Museum a specimen of the latter species
bears a label describing it as Lycopodium arboreum (Sir Joseph Hooker and
Dr Solander; 1769). The twigs of the Tasmanian conifer Microcachyrs
tetragona Hook. f. are very similar in habit to shoots of the recent
Lycopodium tetragonum (fig. 121, C).
In the description of examples of Lycopodites and Selaginellites I have
confined myself to such as appear to be above suspicion either because of
the presence of spore-bearing organs or, in a few cases, because the
specimens of sterile shoots are sufficiently large to show the form of
branching in addition to the texture of the leaves. The two generic names
Lycopodites and Selaginellites are employed for fossil species which there
are substantial grounds for regarding as representatives of Lycopodium and
Selaginella. The designation Selaginellites is adopted only for species
which afford evidence of heterospory; the name Lycopodites, on the other
hand, is used in a comprehensive sense to include all forms—whether
homophyllous or heterophyllous—which are not known to be
heterosporous. This restricted use of the generic name Selaginellites is
advocated by Zeiller[173], who instituted the genus, and by Halle[174] in his
recent paper on herbaceous lycopods.
Lycopodites.
The generic term Lycopodites was used by Brongniart in 1822[175] in
describing some Tertiary examples of slender axes clothed with small scale-
like leaves which he named Lycopodites squamatus. These are fragments of
coniferous shoots. In the Prodrome d’une histoire des végétaux fossiles[176]
Brongniart included several Palaeozoic and Jurassic species in Lycopodites
and instituted a new genus Selaginites, expressing a doubt as to the wisdom
of attempting to draw a generic distinction between the two sets of species.
In a later work[177] he recognised only one undoubted species, Lycopodites
falcatus. The first satisfactory account of fossils referred to Lycopodites is
by Goldenberg[178] who gave the following definition of the genus:
Page 107
—“Branches with leaves spirally disposed or in whorls. Sporangia in the
axil of foliage leaves or borne in terminal strobili.”
It was suggested by Lesquereux[179] that Goldenberg’s definition, which
was intended to apply to herbaceous species, should be extended so as to
include forms with woody stems but which do not in all respects agree with
Lepidodendron. Kidston[180] subsequently adopted Lesquereux’s
modification of Goldenberg’s definition. We cannot draw any well-defined
line between impressions of herbaceous forms and those of small
arborescent species. We use the name Lycopodites for such plants as appear
to agree in habit with recent species of Lycopodium and Selaginella and
which, so far as we know, were not heterosporous: it is highly probable that
some of the species so named had the power of producing secondary wood,
a power possessed by some recent Pteridophytes which never attain the
dimensions of arborescent plants.
It has been shown by Halle[181], who has re-examined several of
Goldenberg’s specimens which have been acquired by the Stockholm
Palaeobotanical Museum, that some of his species of Lycopodites are
heterosporous and therefore referable to Zeiller’s genus Selaginellites.
In 1869 Renault described two species of supposed Palaeozoic Lycopods
as Lycopodium punctatum and L. Renaultii[182], the latter name having been
suggested by Brongniart to whom specimens were submitted. These species
were afterwards recognised by their author as wrongly named and were
transferred to the genus Heterangium[183], a determination which is probably
correct; it is at least certain that the use of the name Lycopodium cannot be
upheld.
We have unfortunately to rely on specimens without petrified tissues for
our information in regard to the history of Lycopodites and Selaginellites.
Among the older fossils referred to Lycopodites are specimens from Lower
Carboniferous rocks at Shap in Westmoreland which Kidston originally
described as Lycopodites Vanuxemi[184], identifying them with Goeppert’s
Sigillaria Vanuxemi[185] founded on German material. In a later paper
Kidston transferred the British specimens of vegetative shoots to a new
genus Archaeosigillaria[186].
Lycopodites Stockii Kidston[187].
axil of foliage leaves or borne in terminal strobili.”
It was suggested by Lesquereux[179] that Goldenberg’s definition, which
was intended to apply to herbaceous species, should be extended so as to
include forms with woody stems but which do not in all respects agree with
Lepidodendron. Kidston[180] subsequently adopted Lesquereux’s
modification of Goldenberg’s definition. We cannot draw any well-defined
line between impressions of herbaceous forms and those of small
arborescent species. We use the name Lycopodites for such plants as appear
to agree in habit with recent species of Lycopodium and Selaginella and
which, so far as we know, were not heterosporous: it is highly probable that
some of the species so named had the power of producing secondary wood,
a power possessed by some recent Pteridophytes which never attain the
dimensions of arborescent plants.
It has been shown by Halle[181], who has re-examined several of
Goldenberg’s specimens which have been acquired by the Stockholm
Palaeobotanical Museum, that some of his species of Lycopodites are
heterosporous and therefore referable to Zeiller’s genus Selaginellites.
In 1869 Renault described two species of supposed Palaeozoic Lycopods
as Lycopodium punctatum and L. Renaultii[182], the latter name having been
suggested by Brongniart to whom specimens were submitted. These species
were afterwards recognised by their author as wrongly named and were
transferred to the genus Heterangium[183], a determination which is probably
correct; it is at least certain that the use of the name Lycopodium cannot be
upheld.
We have unfortunately to rely on specimens without petrified tissues for
our information in regard to the history of Lycopodites and Selaginellites.
Among the older fossils referred to Lycopodites are specimens from Lower
Carboniferous rocks at Shap in Westmoreland which Kidston originally
described as Lycopodites Vanuxemi[184], identifying them with Goeppert’s
Sigillaria Vanuxemi[185] founded on German material. In a later paper
Kidston transferred the British specimens of vegetative shoots to a new
genus Archaeosigillaria[186].
Lycopodites Stockii Kidston[187].
Page 108
The plant so named was discovered in Lower Carboniferous strata of
Eskdale, Dumfries, Scotland; it is represented by imperfectly preserved
shoots bearing a terminal strobilus and was originally described by Kidston
as apparently possessing two kinds of foliage leaves borne in whorls. The
larger leaves have an ovate cordate lamina with an acuminate apex, while
the smaller leaves, which are less distinct, are transversely elongated, and
simulate sporangia in appearance. Dr Kidston’s figure of this species has
recently been reproduced by Professor Bower[188] who speaks of the
supposed smaller leaves as sporangia, a view with which the author of the
species agrees. It would appear that this identification is, however, based
solely on external resemblance and has not been confirmed by the discovery
of any spores. Assuming the sporangial nature of these structures, this
Palaeozoic type represents, as Bower points out, a condition similar to that
in some recent species of Lycopodium in which sporangia are not confined
to a terminal strobilus but occur also in association with ordinary foliage
leaves. The strobilus consists of crowded sporophylls which are too
imperfect to afford any definite evidence as to their homosporous or
heterosporous nature. As Solms-Laubach[189] points out, this type recalls
Lycopodium Phlegmaria among recent species.
Lycopodites Reidii Penhallow.
Professor Penhallow[190] instituted this name for a specimen measuring 8
cm. long by 6 mm. in breadth, collected by Mr Reid from the Old Red
Sandstone of Caithness, consisting of an axis bearing narrow lanceolate
leaves some of which bear sporangia at the base.
Lycopodites Gutbieri Goeppert[191].
1894, Lycopodites elongatus Kidston[192] (not Goldenberg).
The species, figured by Geinitz as Lycopodites Gutbieri[193], from the
Coal-Measures of Saxony is probably a true representative of the genus.
The Saxon specimens are heterophyllous; the larger lanceolate and slightly
falcate leaves arranged in two rows, are 4–5 mm. long while the smaller
leaves are one half or one third this size; some of the dichotomously
branched shoots terminate in long and narrow strobili not unlike those of
Zeiller’s species Selaginellites Suissei[194]. Kidston[195] has included under
this specific name some fragments collected by Hemingway from the Upper
Eskdale, Dumfries, Scotland; it is represented by imperfectly preserved
shoots bearing a terminal strobilus and was originally described by Kidston
as apparently possessing two kinds of foliage leaves borne in whorls. The
larger leaves have an ovate cordate lamina with an acuminate apex, while
the smaller leaves, which are less distinct, are transversely elongated, and
simulate sporangia in appearance. Dr Kidston’s figure of this species has
recently been reproduced by Professor Bower[188] who speaks of the
supposed smaller leaves as sporangia, a view with which the author of the
species agrees. It would appear that this identification is, however, based
solely on external resemblance and has not been confirmed by the discovery
of any spores. Assuming the sporangial nature of these structures, this
Palaeozoic type represents, as Bower points out, a condition similar to that
in some recent species of Lycopodium in which sporangia are not confined
to a terminal strobilus but occur also in association with ordinary foliage
leaves. The strobilus consists of crowded sporophylls which are too
imperfect to afford any definite evidence as to their homosporous or
heterosporous nature. As Solms-Laubach[189] points out, this type recalls
Lycopodium Phlegmaria among recent species.
Lycopodites Reidii Penhallow.
Professor Penhallow[190] instituted this name for a specimen measuring 8
cm. long by 6 mm. in breadth, collected by Mr Reid from the Old Red
Sandstone of Caithness, consisting of an axis bearing narrow lanceolate
leaves some of which bear sporangia at the base.
Lycopodites Gutbieri Goeppert[191].
1894, Lycopodites elongatus Kidston[192] (not Goldenberg).
The species, figured by Geinitz as Lycopodites Gutbieri[193], from the
Coal-Measures of Saxony is probably a true representative of the genus.
The Saxon specimens are heterophyllous; the larger lanceolate and slightly
falcate leaves arranged in two rows, are 4–5 mm. long while the smaller
leaves are one half or one third this size; some of the dichotomously
branched shoots terminate in long and narrow strobili not unlike those of
Zeiller’s species Selaginellites Suissei[194]. Kidston[195] has included under
this specific name some fragments collected by Hemingway from the Upper
Page 109
Coal-Measures of Radstock, Somersetshire, but as only one form of leaf is
seen the reasons for adopting Goeppert’s designation are perhaps hardly
adequate.
Lycopodites ciliatus Kidston[196].
Under this name Kidston describes a small specimen, obtained by
Hemingway from the Middle Coal-Measures of Barnsley in Yorkshire,
consisting of a slender forked axis bearing oval-acuminate leaves
approximately 5 mm. long with a finely ciliate margin. Associated with the
leaves were found spores which Kidston regards as megaspores.
Lycopodites macrophyllus Goldenberg[197].
This species, originally described by Goldenberg from the Coal-
Measures of Saarbrücken has been re-examined by Halle[198] who is unable
to confirm Goldenberg’s statement as to heterophylly. The shoots closely
resemble Selaginellites primaevus[199] (Gold).
seen the reasons for adopting Goeppert’s designation are perhaps hardly
adequate.
Lycopodites ciliatus Kidston[196].
Under this name Kidston describes a small specimen, obtained by
Hemingway from the Middle Coal-Measures of Barnsley in Yorkshire,
consisting of a slender forked axis bearing oval-acuminate leaves
approximately 5 mm. long with a finely ciliate margin. Associated with the
leaves were found spores which Kidston regards as megaspores.
Lycopodites macrophyllus Goldenberg[197].
This species, originally described by Goldenberg from the Coal-
Measures of Saarbrücken has been re-examined by Halle[198] who is unable
to confirm Goldenberg’s statement as to heterophylly. The shoots closely
resemble Selaginellites primaevus[199] (Gold).
Page 110
Fig. 135. Selaginellites and Lycopodites. (After Halle.)
A. Selaginellites primaevus (Gold.). × 10.
B. Megaspore of Selaginellites elongatus (Gold.). × 50.
C. Lycopodites Zeilleri Halle. (Nat. size.)
D. Selaginellites elongatus (Gold.). × 2.
Lycopodites Zeilleri Halle[200]. Fig. 135, C.
Halle has founded this species on specimens, from the Coal-Measures of
Zwickau in Saxony, characterised by dimorphic lanceolate leaves in four
rows, the larger being 4–6 mm. long: the smaller leaves have a ciliate edge.
A comparison is made with the recent species Selaginella arabica Baker, S.
revoluta Bak., and S. armata Bak. in which the leaves are described as
ciliate. In the absence of sporangia and spores the species is placed in the
genus Lycopodites.
A. Selaginellites primaevus (Gold.). × 10.
B. Megaspore of Selaginellites elongatus (Gold.). × 50.
C. Lycopodites Zeilleri Halle. (Nat. size.)
D. Selaginellites elongatus (Gold.). × 2.
Lycopodites Zeilleri Halle[200]. Fig. 135, C.
Halle has founded this species on specimens, from the Coal-Measures of
Zwickau in Saxony, characterised by dimorphic lanceolate leaves in four
rows, the larger being 4–6 mm. long: the smaller leaves have a ciliate edge.
A comparison is made with the recent species Selaginella arabica Baker, S.
revoluta Bak., and S. armata Bak. in which the leaves are described as
ciliate. In the absence of sporangia and spores the species is placed in the
genus Lycopodites.
Page 111
Lycopodites lanceolatus (Brodie). Fig. 136.
1845 Naiadita lanceolata, Brodie[201].
Naiadea acuminata, Buckman[202].
1850 Naiadea lanceolata, Buckman[203].
Naiadea petiolata, Buckman[204].
1900 Naiadites acuminatus, Wickes[205].
1901 Naiadita lanceolata, Sollas[206] (figures showing habit of the
plant).
1904 Lycopodites lanceolatus, Seward[207] (figure showing habit of
the
plant).
1845 Naiadita lanceolata, Brodie[201].
Naiadea acuminata, Buckman[202].
1850 Naiadea lanceolata, Buckman[203].
Naiadea petiolata, Buckman[204].
1900 Naiadites acuminatus, Wickes[205].
1901 Naiadita lanceolata, Sollas[206] (figures showing habit of the
plant).
1904 Lycopodites lanceolatus, Seward[207] (figure showing habit of
the
plant).
Page 112
Fig. 136. Lycopodites lanceolatus (Brodie). (After Miss Sollas. × 40.)
a, Sporangium wall; b, leaf.
c, remains of tubular elements in stem.
Specimens referred to this species were originally recorded by Brodie
from Rhaetic rocks in the Severn valley, the name Naiadita being chosen as
the result of Lindley’s comparison of the small and delicate leaves with
those of recent species of the Monocotyledonous family Naiadaceae. The
species may be described as follows:
Plant slender and moss-like in habit. The axis, which is delicate and
thread-like, bears numerous linear acuminate or narrow ovate leaves
a, Sporangium wall; b, leaf.
c, remains of tubular elements in stem.
Specimens referred to this species were originally recorded by Brodie
from Rhaetic rocks in the Severn valley, the name Naiadita being chosen as
the result of Lindley’s comparison of the small and delicate leaves with
those of recent species of the Monocotyledonous family Naiadaceae. The
species may be described as follows:
Plant slender and moss-like in habit. The axis, which is delicate and
thread-like, bears numerous linear acuminate or narrow ovate leaves
Page 113
reaching a length of approximately 5 mm. Under a low magnifying power
the thin lamina of the leaves is seen to have a superficial layer of polygonal
or rectangular cells arranged in parallel series (fig. 136 b). There is no trace
of midrib or stomata. The sporangia are more or less spherical and short-
stalked, situated at the base of the foliage leaves and containing numerous
tetrads of spores. The spores have a diameter of 0·08 mm.
Buckman founded additional species on differences in the shape of the
leaves but, as Miss Sollas has pointed out, such differences as he noticed
may be detected on the same axis. It was stated in an earlier chapter[208] that
Starkie Gardner, on insufficient evidence, proposed to place Brodie’s plant
among the Mosses. The discovery by Mr Wickes of new material at Pylle
hill near Bristol afforded an opportunity for a re-examination of the species:
this was successfully undertaken by Miss Sollas who was able to dissolve
out spores from the matrix by dilute hydrochloric acid, and to recognise the
remains of internal structure in the slender axes by exposing successive
surfaces with the aid of a hone. It was found that sporangia occurred at the
base of some of the leaves containing numerous tetrads of spores, the
individual spores having a diameter of 0·08 mm., apparently twice as large
as those of any recent species of Lycopodium. Fig. 136 shows a
sporangium, a, at the base of a leaf, b. Indications of tubular elements were
recognised in the stem and it is noteworthy that although the outlines of
epidermal cells on the leaves are well preserved no stomata were found.
The leaves of the recent American species Lycopodium alopecuroides Linn.
var. aquaticum Spring[209], which lives under water, possess stomata. It is
probable that in Lycopodites lanceolatus the leaves had a very thin lamina
and may have been similar in structure to those of recent Mosses; the plant
possibly lived in very humid situations or grew submerged. Miss Sollas’s
investigations afford a satisfactory demonstration of the lycopodiaceous
nature of this small Rhaetic species: as I have elsewhere suggested[210], the
generic name Lycopodites should be substituted for that of Naiadita.
Examples of this species may be seen in the British Museum.
The Rhaetic species from Scania, Lycopodites scanicus Nath.[211] (in litt.),
recently re-described by Halle and originally referred by Nathorst to
Gleichenia affords another example of the occurrence of a small herbaceous
lycopod of Rhaetic age.
the thin lamina of the leaves is seen to have a superficial layer of polygonal
or rectangular cells arranged in parallel series (fig. 136 b). There is no trace
of midrib or stomata. The sporangia are more or less spherical and short-
stalked, situated at the base of the foliage leaves and containing numerous
tetrads of spores. The spores have a diameter of 0·08 mm.
Buckman founded additional species on differences in the shape of the
leaves but, as Miss Sollas has pointed out, such differences as he noticed
may be detected on the same axis. It was stated in an earlier chapter[208] that
Starkie Gardner, on insufficient evidence, proposed to place Brodie’s plant
among the Mosses. The discovery by Mr Wickes of new material at Pylle
hill near Bristol afforded an opportunity for a re-examination of the species:
this was successfully undertaken by Miss Sollas who was able to dissolve
out spores from the matrix by dilute hydrochloric acid, and to recognise the
remains of internal structure in the slender axes by exposing successive
surfaces with the aid of a hone. It was found that sporangia occurred at the
base of some of the leaves containing numerous tetrads of spores, the
individual spores having a diameter of 0·08 mm., apparently twice as large
as those of any recent species of Lycopodium. Fig. 136 shows a
sporangium, a, at the base of a leaf, b. Indications of tubular elements were
recognised in the stem and it is noteworthy that although the outlines of
epidermal cells on the leaves are well preserved no stomata were found.
The leaves of the recent American species Lycopodium alopecuroides Linn.
var. aquaticum Spring[209], which lives under water, possess stomata. It is
probable that in Lycopodites lanceolatus the leaves had a very thin lamina
and may have been similar in structure to those of recent Mosses; the plant
possibly lived in very humid situations or grew submerged. Miss Sollas’s
investigations afford a satisfactory demonstration of the lycopodiaceous
nature of this small Rhaetic species: as I have elsewhere suggested[210], the
generic name Lycopodites should be substituted for that of Naiadita.
Examples of this species may be seen in the British Museum.
The Rhaetic species from Scania, Lycopodites scanicus Nath.[211] (in litt.),
recently re-described by Halle and originally referred by Nathorst to
Gleichenia affords another example of the occurrence of a small herbaceous
lycopod of Rhaetic age.
Page 114
Fig. 137. Lycopodites falcatus L. and H. From the Inferior Oolite of Yorkshire. (Nat. size.
M.S.)
Lycopodites falcatus Lind. and Hutt. Fig. 137.
1831 Lycopodites falcatus, Lindley and Hutton[212].
1838 Muscites falcatus, Sternberg[213].
1870 Lycopodium falcatum, Schimper[214].
In 1822 Young and Bird[215] figured a specimen from the Inferior Oolite
rocks of the Yorkshire coast bearing “small round crowded leaves,” which
was afterwards described by Lindley from additional material obtained
from Cloughton near Scarborough as Lycopodites falcatus. The example
represented in fig. 137 shows the dichotomously branched shoots bearing
two rows of broadly falcate leaves. A careful examination of the type-
specimen[216] revealed traces of what appeared to be smaller leaves, but
there is no satisfactory proof of heterophylly. No sporangia or spores have
been found. This British species has been recorded from Lower Jurassic or
Rhaetic rocks of Bornholm[217] and a similar though probably not identical
type, Lycopodites Victoriae[218], has been recognised in Jurassic strata of
Australia (South Gippsland, Victoria). An Indian plant described by Oldham
and Morris[219] from the Jurassic flora of the Rajmahal hills as Araucarites
M.S.)
Lycopodites falcatus Lind. and Hutt. Fig. 137.
1831 Lycopodites falcatus, Lindley and Hutton[212].
1838 Muscites falcatus, Sternberg[213].
1870 Lycopodium falcatum, Schimper[214].
In 1822 Young and Bird[215] figured a specimen from the Inferior Oolite
rocks of the Yorkshire coast bearing “small round crowded leaves,” which
was afterwards described by Lindley from additional material obtained
from Cloughton near Scarborough as Lycopodites falcatus. The example
represented in fig. 137 shows the dichotomously branched shoots bearing
two rows of broadly falcate leaves. A careful examination of the type-
specimen[216] revealed traces of what appeared to be smaller leaves, but
there is no satisfactory proof of heterophylly. No sporangia or spores have
been found. This British species has been recorded from Lower Jurassic or
Rhaetic rocks of Bornholm[217] and a similar though probably not identical
type, Lycopodites Victoriae[218], has been recognised in Jurassic strata of
Australia (South Gippsland, Victoria). An Indian plant described by Oldham
and Morris[219] from the Jurassic flora of the Rajmahal hills as Araucarites
Page 115
(?) gracilis and subsequently transferred by Feistmantel to Schimper’s
genus Cheirolepis[220] may be identical with the Yorkshire species. The
Jurassic fragments described by Heer from Siberia as Lycopodites
tenerrimus[221] may be lycopodiaceous, but they are of no botanical interest.
Other examples of Mesozoic Lycopods have been recorded, but in the
absence of well-preserved shoots and sporangia they are noteworthy only as
pointing to a wide distribution of Lycopodites in Jurassic and Cretaceous
floras[222].
From Tertiary strata species of supposed herbaceous lycopods have been
figured by several authors, one of the best of which is Selaginella Berthoudi
Lesq.[223] from Tertiary beds in Colorado. This species agrees very closely in
the two forms of leaf with Selaginella grandis, but as the specimens are
sterile we have not sufficient justification for the employment of the generic
name Selaginellites.
Selaginellites.
This generic name has been instituted by Zeiller[224] for specimens from
the coal basis of Blanzy (France). It is applied to heterosporous species with
the habit of Selaginella: Zeiller preferred the designation Selaginellites to
Selaginella on the ground that the type species differs from recent forms in
having more than four megaspores in each megasporangium. It is, however,
convenient to extend the term to all heterosporous fossil species irrespective
of the spore-output.
Selaginellites Suissei Zeiller.
This species was described in Zeiller’s preliminary note[225] as
Lycopodites Suissei, but he afterwards transferred it to the genus
Selaginellites. In habit the plant bears a close resemblance to Lycopodites
macrophyllus of Goldenberg; the shoots, 1–3 mm. thick, are branched in a
more or less dichotomous fashion and bear tetrastichous leaves. The larger
leaves reach a length of 4–6 mm. and a breadth of 2–3 mm.; the smaller
leaves are described as almost invisible, closely applied to the axis, oval-
lanceolate and 1–2 mm. long with a breadth of 0·5–0·75 mm. Long and
narrow strobili (15 cm. by 8–10 mm.) terminate the fertile branches; these
bear crowded sporophylls with a triangular lamina and finely denticulate
genus Cheirolepis[220] may be identical with the Yorkshire species. The
Jurassic fragments described by Heer from Siberia as Lycopodites
tenerrimus[221] may be lycopodiaceous, but they are of no botanical interest.
Other examples of Mesozoic Lycopods have been recorded, but in the
absence of well-preserved shoots and sporangia they are noteworthy only as
pointing to a wide distribution of Lycopodites in Jurassic and Cretaceous
floras[222].
From Tertiary strata species of supposed herbaceous lycopods have been
figured by several authors, one of the best of which is Selaginella Berthoudi
Lesq.[223] from Tertiary beds in Colorado. This species agrees very closely in
the two forms of leaf with Selaginella grandis, but as the specimens are
sterile we have not sufficient justification for the employment of the generic
name Selaginellites.
Selaginellites.
This generic name has been instituted by Zeiller[224] for specimens from
the coal basis of Blanzy (France). It is applied to heterosporous species with
the habit of Selaginella: Zeiller preferred the designation Selaginellites to
Selaginella on the ground that the type species differs from recent forms in
having more than four megaspores in each megasporangium. It is, however,
convenient to extend the term to all heterosporous fossil species irrespective
of the spore-output.
Selaginellites Suissei Zeiller.
This species was described in Zeiller’s preliminary note[225] as
Lycopodites Suissei, but he afterwards transferred it to the genus
Selaginellites. In habit the plant bears a close resemblance to Lycopodites
macrophyllus of Goldenberg; the shoots, 1–3 mm. thick, are branched in a
more or less dichotomous fashion and bear tetrastichous leaves. The larger
leaves reach a length of 4–6 mm. and a breadth of 2–3 mm.; the smaller
leaves are described as almost invisible, closely applied to the axis, oval-
lanceolate and 1–2 mm. long with a breadth of 0·5–0·75 mm. Long and
narrow strobili (15 cm. by 8–10 mm.) terminate the fertile branches; these
bear crowded sporophylls with a triangular lamina and finely denticulate
Page 116
margin. Oval sporangia were found on the lower sporophylls containing
16–24 spherical megaspores 0·6–0·65 mm. in diameter. The outer
membrane of the spore is characterised by fine anastomosing ridges and
thin plates radiating from the apex and forming an equatorial collarette. The
microspores have a diameter of 40–60μ and the same type of outer
membrane as in the megaspores. The megaspores of the recent species
Selaginella caulescens, as figured by Bennie and Kidston[226], resemble
those of the Palaeozoic type in the presence of an equatorial flange. It is
interesting to find that, in spite of the occurrence of 16–24 megaspores in a
single sporangium the size of the fossil spores exceeds that of the recent
species.
Selaginellites primaevus (Gold.). Fig. 135, A, fig. 138.
1855 Lycopodites primaevus, Goldenberg[227].
1870 Lycopodium primaevum, Schimper[228].
1907 Selaginellites primaevus, Halle[229].
16–24 spherical megaspores 0·6–0·65 mm. in diameter. The outer
membrane of the spore is characterised by fine anastomosing ridges and
thin plates radiating from the apex and forming an equatorial collarette. The
microspores have a diameter of 40–60μ and the same type of outer
membrane as in the megaspores. The megaspores of the recent species
Selaginella caulescens, as figured by Bennie and Kidston[226], resemble
those of the Palaeozoic type in the presence of an equatorial flange. It is
interesting to find that, in spite of the occurrence of 16–24 megaspores in a
single sporangium the size of the fossil spores exceeds that of the recent
species.
Selaginellites primaevus (Gold.). Fig. 135, A, fig. 138.
1855 Lycopodites primaevus, Goldenberg[227].
1870 Lycopodium primaevum, Schimper[228].
1907 Selaginellites primaevus, Halle[229].
Page 117
Fig. 138. Selaginellites primaevus (Gold.). (After Goldenberg.)
In habit this species, first recorded by Goldenberg from the Coal-
Measures of Saarbrücken, is similar to S. Suissei Zeill.
The drawing reproduced in fig. 138 is a copy of that of the type-
specimen: another specimen, named by Goldenberg, is figured by Halle in
his recently published paper. The leaves appear to be distichous: no smaller
leaves have been detected, though Halle is inclined to regard the plant as
heterophyllous. The sporophylls, borne in slender terminal strobili, are
smaller than the foliage leaves and spirally disposed (fig. 138; smaller
In habit this species, first recorded by Goldenberg from the Coal-
Measures of Saarbrücken, is similar to S. Suissei Zeill.
The drawing reproduced in fig. 138 is a copy of that of the type-
specimen: another specimen, named by Goldenberg, is figured by Halle in
his recently published paper. The leaves appear to be distichous: no smaller
leaves have been detected, though Halle is inclined to regard the plant as
heterophyllous. The sporophylls, borne in slender terminal strobili, are
smaller than the foliage leaves and spirally disposed (fig. 138; smaller
Page 118
specimen). Halle succeeded in demonstrating that some of the sporangia
contained a single tetrad of spores, each spore having a diameter of 0·4–0·5
mm. No microspores were found, but it is clear that the species was
heterosporous and that it agrees with recent species in having only four
spores in the megasporangium.
Selaginellites elongatus (Gold.). Fig. 135, B, D.
contained a single tetrad of spores, each spore having a diameter of 0·4–0·5
mm. No microspores were found, but it is clear that the species was
heterosporous and that it agrees with recent species in having only four
spores in the megasporangium.
Selaginellites elongatus (Gold.). Fig. 135, B, D.
Page 119
1855 Lycopodites elongatus, Goldenberg[230].
1870 Lycopodium elongatum, Schimper[231].
The shoots of this species resemble the recent Lycopodium complanatum;
they differ from those of Selaginellites primaevus in their long and narrow
branches which bear two forms of leaf. The longer leaves, arranged in
opposite pairs, are slightly falcate; the smaller leaves are appressed to the
axis and have a triangular cordate lamina. Another peculiarity of this
species is the occurrence of sporangia in the axil of the foliage leaves, a
feature characteristic of the recent Lycopodium Selago. In recent species of
Selaginella the sporophylls are always in strobili. No microspores have
been found nor the walls of megasporangia, but tetrads of megaspores were
isolated by Halle: the spores have three radiating ridges (fig. 135, B)
connected by an equatorial ridge. Halle estimates the number of spores
(0·45 mm. in diameter) in a sporangium at 20 to 30. In size as in number
the spores exceed those of recent species and agree more nearly with the
megaspores of S. Suissei.
It would seem to be a general rule that the spores (megaspores) of the
fossil herbaceous species exceeded considerably in dimensions those of
recent forms and on the other hand were smaller than those of the
Palaeozoic arborescent species.
There can be little doubt that some of the Mesozoic and Tertiary species
included under Lycopodites agree more closely with the recent genus
Selaginella than with Lycopodium, but this does not constitute an argument
of any importance against the restricted use of the designation Selaginellites
which we have adopted. From a botanical point of view the various records
of Lycopodites and Selaginellites have but a minor importance; they are not
sufficiently numerous to throw any light on questions of distribution in
former periods, nor is the preservation of the material such as to enable us
to compare the fossil with recent types either as regards their anatomy or,
except in a few cases, their sporangia and spores. The Palaeozoic species
are interesting as revealing less reduction in the number of spores produced
in the megasporangia. Among existing Pteridophytes the genus Isoetes
agrees more closely than Selaginella, as regards the number of megaspores
in each sporangium, with such fossils as Selaginellites Suissei and S.
elongatus.
1870 Lycopodium elongatum, Schimper[231].
The shoots of this species resemble the recent Lycopodium complanatum;
they differ from those of Selaginellites primaevus in their long and narrow
branches which bear two forms of leaf. The longer leaves, arranged in
opposite pairs, are slightly falcate; the smaller leaves are appressed to the
axis and have a triangular cordate lamina. Another peculiarity of this
species is the occurrence of sporangia in the axil of the foliage leaves, a
feature characteristic of the recent Lycopodium Selago. In recent species of
Selaginella the sporophylls are always in strobili. No microspores have
been found nor the walls of megasporangia, but tetrads of megaspores were
isolated by Halle: the spores have three radiating ridges (fig. 135, B)
connected by an equatorial ridge. Halle estimates the number of spores
(0·45 mm. in diameter) in a sporangium at 20 to 30. In size as in number
the spores exceed those of recent species and agree more nearly with the
megaspores of S. Suissei.
It would seem to be a general rule that the spores (megaspores) of the
fossil herbaceous species exceeded considerably in dimensions those of
recent forms and on the other hand were smaller than those of the
Palaeozoic arborescent species.
There can be little doubt that some of the Mesozoic and Tertiary species
included under Lycopodites agree more closely with the recent genus
Selaginella than with Lycopodium, but this does not constitute an argument
of any importance against the restricted use of the designation Selaginellites
which we have adopted. From a botanical point of view the various records
of Lycopodites and Selaginellites have but a minor importance; they are not
sufficiently numerous to throw any light on questions of distribution in
former periods, nor is the preservation of the material such as to enable us
to compare the fossil with recent types either as regards their anatomy or,
except in a few cases, their sporangia and spores. The Palaeozoic species
are interesting as revealing less reduction in the number of spores produced
in the megasporangia. Among existing Pteridophytes the genus Isoetes
agrees more closely than Selaginella, as regards the number of megaspores
in each sporangium, with such fossils as Selaginellites Suissei and S.
elongatus.
Page 120
It would seem that in most Palaeozoic species heterospory had not
reached the same stage of development as in the recent genus Selaginella in
which the megaspores do not exceed four in each sporangium. In
Selaginellites primaevus, however, the heterospory appears to be precisely
of the same type as in existing species.
Lycostrobus.
The generic name Lycostrobus has recently been instituted by
Nathorst[232] for certain specimens of a lycopodiaceous strobilus, from the
Rhaetic strata of Scania, which he formerly referred to the genus
Androstrobus[233].
Lycostrobus Scotti Nathorst. Fig. 139.
The fossil described under this name is of special interest as affording an
example of a Mesozoic lycopodiaceous cone comparable in habit and in
size with some of the largest examples of Palaeozoic Lepidostrobi, the
cones of Lepidodendron. The Swedish fossil from Upper Rhaetic strata of
Helsingborg (Scania) was originally designated Androstrobus Scotti, the
generic name being adopted in view of the close resemblance of the form of
the strobilus to the male flower of a Cycad. A more complete examination
has shown that the bodies, which were thought to be pollen-sacs—though
Nathorst recognised certain differences between them and the pollen-sacs of
lycopods—are the megaspores of a lycopod. Microspores have also been
identified. The axis of the cone has a breadth of 2 cm. with a peduncle
which may be naked or provided with a few small scales; the sporophyll
region of the axis reached a length of at least 12 cm. The spirally disposed
sporophylls terminate in a rhombic distal end which may represent the
original termination or they may have been prolonged upwards as free
laminae. Each sporophyll bears on its upper face a single large sporangium
containing either megaspores or microspores: the megaspores, 0·55–0·60
mm. in diameter, are finely granulate and bear small warty thorns or more
slender pointed appendages. The microspores, after treatment with eau de
Javelle, were found to measure 36–44μ while others which had been treated
with ammonia reached 54μ in diameter. Nathorst describes the microspores
as occurring in spherical groups or balls, which it is suggested may be
compared with the groups of spores separated by strands of sterile tissue
reached the same stage of development as in the recent genus Selaginella in
which the megaspores do not exceed four in each sporangium. In
Selaginellites primaevus, however, the heterospory appears to be precisely
of the same type as in existing species.
Lycostrobus.
The generic name Lycostrobus has recently been instituted by
Nathorst[232] for certain specimens of a lycopodiaceous strobilus, from the
Rhaetic strata of Scania, which he formerly referred to the genus
Androstrobus[233].
Lycostrobus Scotti Nathorst. Fig. 139.
The fossil described under this name is of special interest as affording an
example of a Mesozoic lycopodiaceous cone comparable in habit and in
size with some of the largest examples of Palaeozoic Lepidostrobi, the
cones of Lepidodendron. The Swedish fossil from Upper Rhaetic strata of
Helsingborg (Scania) was originally designated Androstrobus Scotti, the
generic name being adopted in view of the close resemblance of the form of
the strobilus to the male flower of a Cycad. A more complete examination
has shown that the bodies, which were thought to be pollen-sacs—though
Nathorst recognised certain differences between them and the pollen-sacs of
lycopods—are the megaspores of a lycopod. Microspores have also been
identified. The axis of the cone has a breadth of 2 cm. with a peduncle
which may be naked or provided with a few small scales; the sporophyll
region of the axis reached a length of at least 12 cm. The spirally disposed
sporophylls terminate in a rhombic distal end which may represent the
original termination or they may have been prolonged upwards as free
laminae. Each sporophyll bears on its upper face a single large sporangium
containing either megaspores or microspores: the megaspores, 0·55–0·60
mm. in diameter, are finely granulate and bear small warty thorns or more
slender pointed appendages. The microspores, after treatment with eau de
Javelle, were found to measure 36–44μ while others which had been treated
with ammonia reached 54μ in diameter. Nathorst describes the microspores
as occurring in spherical groups or balls, which it is suggested may be
compared with the groups of spores separated by strands of sterile tissue
Page 121
(trabeculae) in the large sporangia of Isoetes (cf. fig. 133, H). If this
comparison is sound it would point to a more complete septation of the
sporangium in Lycostrobus than in any recent species of Isoetes. The size of
the strobilus would seem to indicate the persistence into the Rhaetic era of
an arborescent lycopodiaceous type; but the appearance and manner of
preservation of the axis is interpreted by Nathorst as evidence of a
herbaceous rather than a woody structure. He is disposed to regard Isoetes
as the most nearly allied existing genus.
Fig. 139. Lycostrobus Scotti, Nath. (After Nathorst; ⅘ nat. size.)
comparison is sound it would point to a more complete septation of the
sporangium in Lycostrobus than in any recent species of Isoetes. The size of
the strobilus would seem to indicate the persistence into the Rhaetic era of
an arborescent lycopodiaceous type; but the appearance and manner of
preservation of the axis is interpreted by Nathorst as evidence of a
herbaceous rather than a woody structure. He is disposed to regard Isoetes
as the most nearly allied existing genus.
Fig. 139. Lycostrobus Scotti, Nath. (After Nathorst; ⅘ nat. size.)
Page 122
The comparison made by Nathorst with Isoetes is based on a resemblance
between the spores of the two genera and on the evidence, which is not
decisive, of the existence of sterile strands of tissue in the sporangia of
Lycostrobus. This similarity is however hardly of sufficient importance to
justify the inclusion of the Rhaetic strobilus in the Isoetaceae. In size and in
the arrangement and form of the sporophylls the cone presents a much
closer resemblance to Lepidodendron than to Isoetes. It is probably
advisable to regard this Rhaetic type simply as a lycopodiaceous genus
which we are unable, without additional information, to assign to a
particular position.
The opinion expressed by Professor Fliche[234] that the plant described by
Schimper and Mougeot as Caulopteris tessellata, a supposed tree-fern stem,
from Triassic rocks of Lorraine, is more probably a large lycopodiaceous
stem, either a Lepidodendron or a new genus, is worthy of note in reference
to Nathorst’s account of Lycostrobus.
In habit the fossil strobilus may be compared with the Triassic genus
Pleuromeia, but the position of the sporangia on the sporophylls constitutes
a well-marked difference. The most important result of Nathorst’s skillful
treatment of this interesting fossil by chemical microscopic methods is the
demonstration of the existence of a large heterosporous type of
lycopodiaceous cone in a Rhaetic flora.
Poecilitostachys.
Under this generic name M. Fliche[235] has briefly described a fertile
lycopodiaceous shoot from the Triassic rocks of Epinal in France: the type
species Poecilitostachys Hangi consists of a cylindrical axis, 10 cm. × 5
mm., deprived of leaves and terminating in a rounded receptacle bearing a
capitulum of bracts or fertile leaves. Detached megasporangia containing
small globular bodies found in association with the capitulum are compared
with the megasporangia of Isoetes.
between the spores of the two genera and on the evidence, which is not
decisive, of the existence of sterile strands of tissue in the sporangia of
Lycostrobus. This similarity is however hardly of sufficient importance to
justify the inclusion of the Rhaetic strobilus in the Isoetaceae. In size and in
the arrangement and form of the sporophylls the cone presents a much
closer resemblance to Lepidodendron than to Isoetes. It is probably
advisable to regard this Rhaetic type simply as a lycopodiaceous genus
which we are unable, without additional information, to assign to a
particular position.
The opinion expressed by Professor Fliche[234] that the plant described by
Schimper and Mougeot as Caulopteris tessellata, a supposed tree-fern stem,
from Triassic rocks of Lorraine, is more probably a large lycopodiaceous
stem, either a Lepidodendron or a new genus, is worthy of note in reference
to Nathorst’s account of Lycostrobus.
In habit the fossil strobilus may be compared with the Triassic genus
Pleuromeia, but the position of the sporangia on the sporophylls constitutes
a well-marked difference. The most important result of Nathorst’s skillful
treatment of this interesting fossil by chemical microscopic methods is the
demonstration of the existence of a large heterosporous type of
lycopodiaceous cone in a Rhaetic flora.
Poecilitostachys.
Under this generic name M. Fliche[235] has briefly described a fertile
lycopodiaceous shoot from the Triassic rocks of Epinal in France: the type
species Poecilitostachys Hangi consists of a cylindrical axis, 10 cm. × 5
mm., deprived of leaves and terminating in a rounded receptacle bearing a
capitulum of bracts or fertile leaves. Detached megasporangia containing
small globular bodies found in association with the capitulum are compared
with the megasporangia of Isoetes.
Page 123
Page 124
CHAPTER XV.
Arborescent Lycopodiales.
Among the best known plants in the Palaeozoic floras are the genera
Lepidodendron and Sigillaria, types which are often spoken of as Giant
Club-Mosses or as ancestors of existing species of Lycopodium and
Selaginella. Of these genera, but more particularly of Lepidodendron, we
possess abundant records in a condition which have made it possible to
obtain fairly complete information not only in regard to habit and external
features but as to the anatomical characters of both vegetative and
reproductive shoots. The structure of Lepidodendron differs too widely
from that of recent Club-Mosses (species of Lycopodium) to justify the
statement that this prominent member of the Palaeozoic vegetation may be
regarded as a direct ancestor of any living plant. There is at least no doubt
that Lepidodendron and Sigillaria must be included in the Pteridophyta. The
description by Dr Scott[236] of the genus Lepidocarpon, founded on petrified
specimens of strobili, demonstrated the existence of a type of
lycopodiaceous plant in the Carboniferous period distinguished from all
living representatives of the group by the possession of integumented
megaspores, which may fairly be styled seeds. Lepidocarpon and another
seed-bearing plant Miadesmia are described under a separate heading as
lycopodiaceous types characterised by an important morphological feature,
which among recent plants constitutes a differentiating character between
the Pteridophytes and the Phanerogams.
Lepidodendron.
i. General.
The genus Lepidodendron included species comparable in size with
existing forest trees. A tapered trunk rose vertically to a height of 100 feet
or upwards from a dichotomously branched subterranean axis of which the
Arborescent Lycopodiales.
Among the best known plants in the Palaeozoic floras are the genera
Lepidodendron and Sigillaria, types which are often spoken of as Giant
Club-Mosses or as ancestors of existing species of Lycopodium and
Selaginella. Of these genera, but more particularly of Lepidodendron, we
possess abundant records in a condition which have made it possible to
obtain fairly complete information not only in regard to habit and external
features but as to the anatomical characters of both vegetative and
reproductive shoots. The structure of Lepidodendron differs too widely
from that of recent Club-Mosses (species of Lycopodium) to justify the
statement that this prominent member of the Palaeozoic vegetation may be
regarded as a direct ancestor of any living plant. There is at least no doubt
that Lepidodendron and Sigillaria must be included in the Pteridophyta. The
description by Dr Scott[236] of the genus Lepidocarpon, founded on petrified
specimens of strobili, demonstrated the existence of a type of
lycopodiaceous plant in the Carboniferous period distinguished from all
living representatives of the group by the possession of integumented
megaspores, which may fairly be styled seeds. Lepidocarpon and another
seed-bearing plant Miadesmia are described under a separate heading as
lycopodiaceous types characterised by an important morphological feature,
which among recent plants constitutes a differentiating character between
the Pteridophytes and the Phanerogams.
Lepidodendron.
i. General.
The genus Lepidodendron included species comparable in size with
existing forest trees. A tapered trunk rose vertically to a height of 100 feet
or upwards from a dichotomously branched subterranean axis of which the
Page 125
spreading branches, clothed with numerous rootlets, grew in a horizontal
direction probably in a swampy soil or possibly under water. A description
by Mr Rodway[237] of Lycopods on the border of a savannah in Guiana
forming a miniature forest of Pine-like Lycopodiums might, with the
omission of the qualifying adjective, be applied with equal force to a grove
of Lepidodendra. The equal dichotomy of many of the branches gave to the
tree a habit in striking contrast to that of our modern forest trees, but, on the
other hand, in close agreement with that of such recent species of
Lycopodium as L. cernuum (fig. 123), L. obscurum (fig. 124) and other
types. Linear or oval cones terminated some of the more slender branches
(fig. 188) agreeing in size and form with the cones of the Spruce Fir and
other conifers or with the male flowers of species of Araucaria, e.g. A.
imbricata. Needle-like leaves, varying considerably in length in different
species, covered the surface of young shoots in crowded spirals and their
decurrent bases or leaf-cushions formed an encasing cylinder continuous
with the outer cortex. The fact that leaves are usually found attached only to
branches of comparatively small diameter would seem to show that
Lepidodendron, though an evergreen, did not retain its foliage even for so
long a period as do some recent conifers.
By the activity of a zone of growing tissue encircling the cylinder of
wood the main trunk and branches grew in thickness year by year: the
general uniformity in size of the secondary conducting elements affords no
indication of changing seasons. As the branches grew stouter and shed their
leaves the surface of the bark resembled in some degree that of a Spruce Fir
and other species of Picea, in which the leaf-scars form the upper limit of
prominent peg-like projections, which, at first contiguous and regular in
contour, afterwards become less regular and separated by grooves (fig. 140)
and at a later stage lose their outline as the bark is stretched to the tearing
point (fig. 140, C). The leafless branches of Lepidodendron were covered
with spirally disposed oval cushions less peg-like and larger than the
decurrent leaf-bases of Picea, which show in the upper third of their length
a clean-cut triangular area and swell out below into two prominent cheeks
separated by a median groove and tapering with decreasing thickness to a
pointed base, which in some forms (e.g. Lepidodendron Veltheimianum, fig.
185, C, D), is prolonged as a curved ridge to the summit of a lower leaf-
cushion.
direction probably in a swampy soil or possibly under water. A description
by Mr Rodway[237] of Lycopods on the border of a savannah in Guiana
forming a miniature forest of Pine-like Lycopodiums might, with the
omission of the qualifying adjective, be applied with equal force to a grove
of Lepidodendra. The equal dichotomy of many of the branches gave to the
tree a habit in striking contrast to that of our modern forest trees, but, on the
other hand, in close agreement with that of such recent species of
Lycopodium as L. cernuum (fig. 123), L. obscurum (fig. 124) and other
types. Linear or oval cones terminated some of the more slender branches
(fig. 188) agreeing in size and form with the cones of the Spruce Fir and
other conifers or with the male flowers of species of Araucaria, e.g. A.
imbricata. Needle-like leaves, varying considerably in length in different
species, covered the surface of young shoots in crowded spirals and their
decurrent bases or leaf-cushions formed an encasing cylinder continuous
with the outer cortex. The fact that leaves are usually found attached only to
branches of comparatively small diameter would seem to show that
Lepidodendron, though an evergreen, did not retain its foliage even for so
long a period as do some recent conifers.
By the activity of a zone of growing tissue encircling the cylinder of
wood the main trunk and branches grew in thickness year by year: the
general uniformity in size of the secondary conducting elements affords no
indication of changing seasons. As the branches grew stouter and shed their
leaves the surface of the bark resembled in some degree that of a Spruce Fir
and other species of Picea, in which the leaf-scars form the upper limit of
prominent peg-like projections, which, at first contiguous and regular in
contour, afterwards become less regular and separated by grooves (fig. 140)
and at a later stage lose their outline as the bark is stretched to the tearing
point (fig. 140, C). The leafless branches of Lepidodendron were covered
with spirally disposed oval cushions less peg-like and larger than the
decurrent leaf-bases of Picea, which show in the upper third of their length
a clean-cut triangular area and swell out below into two prominent cheeks
separated by a median groove and tapering with decreasing thickness to a
pointed base, which in some forms (e.g. Lepidodendron Veltheimianum, fig.
185, C, D), is prolonged as a curved ridge to the summit of a lower leaf-
cushion.
Page 126
Fig. 140. Picea excelsa. Shoots of different ages showing changes in the appearance of the
leaf-cushions: a leaf attached to a cushion in fig. A. (Slightly enlarged.)
A portion of the cushion below the triangular leaf-scar often shows
transverse gaping cracks or depressions (fig. 185, C) such as occur on a
smaller scale on the older cushions of a Fir twig (fig. 140). Secondary
thickening, as in recent trees, is not confined to the vascular cylinder but at
an early stage, frequently before there are any signs of secondary wood, the
outer region of the broad cortex becomes the seat of active cell-formation
which results in the addition of a considerable thickness to the bark. At a
later stage of increase in girth, the leaf-cushions are stretched apart and the
original surface-features become obliterated by vertical cracks and by the
exfoliation of the superficial tissues[238].
Some species of Lepidodendron produced branches characterised by
spiral or vertical series of scars; these in older shoots were replaced by
depressions having a diameter of several inches and comparable in
appearance, as also perhaps in manner of formation, with the scars left on
the stem of a Kauri Pine (Agathis australis)[239] on the abscission of lateral
branches by a natural process. These shoots, known as Ulodendron, are
described in a subsequent section. (page 128.)
A fully-grown Lepidodendron must have been an impressive tree,
probably of sombre colour, relieved by the encircling felt of green needles
on the young pendulous twigs. The leaves of some species were similar to
those of a fir while in others they resembled the filiform needles of the
leaf-cushions: a leaf attached to a cushion in fig. A. (Slightly enlarged.)
A portion of the cushion below the triangular leaf-scar often shows
transverse gaping cracks or depressions (fig. 185, C) such as occur on a
smaller scale on the older cushions of a Fir twig (fig. 140). Secondary
thickening, as in recent trees, is not confined to the vascular cylinder but at
an early stage, frequently before there are any signs of secondary wood, the
outer region of the broad cortex becomes the seat of active cell-formation
which results in the addition of a considerable thickness to the bark. At a
later stage of increase in girth, the leaf-cushions are stretched apart and the
original surface-features become obliterated by vertical cracks and by the
exfoliation of the superficial tissues[238].
Some species of Lepidodendron produced branches characterised by
spiral or vertical series of scars; these in older shoots were replaced by
depressions having a diameter of several inches and comparable in
appearance, as also perhaps in manner of formation, with the scars left on
the stem of a Kauri Pine (Agathis australis)[239] on the abscission of lateral
branches by a natural process. These shoots, known as Ulodendron, are
described in a subsequent section. (page 128.)
A fully-grown Lepidodendron must have been an impressive tree,
probably of sombre colour, relieved by the encircling felt of green needles
on the young pendulous twigs. The leaves of some species were similar to
those of a fir while in others they resembled the filiform needles of the
Page 127
Himalayan Pine (Pinus longifolia). The occasional presence of delicate
hyphae in the tissues of Lepidodendron demonstrates susceptibility to
fungal pests.
Architecturally, if one may use the term, Lepidodendron owed its power
of resistance to the bending force of the wind to its stout outer bark formed
of thick-walled elements produced by the activity of a cylinder of cortical
meristem (figs. 148, 172, etc.). The vascular axis, of insignificant diameter
in proportion to the size of the stem (figs. 152, 153, 172, 181, A), must have
played a subordinate part, from a mechanical point of view, as compared
with the solid mass of wood of a Pine or an Oak.
• • • • •
Within the compass of a text-book it is impossible, even if it were
desirable, to include an account of the majority of the species of the widely
distributed Palaeozoic genus Lepidodendron. In spite of the great number of
known species of this common member of Carboniferous floras, our
knowledge of the type as a whole is deficient in many points, and such
information as we possess needs systematising and extending by
comparative treatment based on a re-examination of available data.
In order to appreciate the meaning of certain external features
characteristic of Lepidodendron stems it is essential to have some
knowledge of the internal structure.
A dual system of terminology has been unavoidably adopted for species
of Lepidodendron: the majority of specific names have been assigned to
fossils known only in the form of casts or impressions, while petrified
fragments, which unfortunately seldom show the surface-features, have
received another set of names. A glance at the older palaeobotanical
literature reveals the existence of several generic designations, which fuller
information has shown to have been applied to lepidodendroid shoots
deprived of some of their superficial tissues before fossilisation and
differing considerably in appearance from the more complete branches of
the same species[240]. It has in some instances been possible to correlate the
two sets of specimens, casts or impressions, showing external features, and
petrified fragments. We may reasonably expect that future discoveries will
enable us to piece together as definite specific types specimens at present
labelled with different names.
hyphae in the tissues of Lepidodendron demonstrates susceptibility to
fungal pests.
Architecturally, if one may use the term, Lepidodendron owed its power
of resistance to the bending force of the wind to its stout outer bark formed
of thick-walled elements produced by the activity of a cylinder of cortical
meristem (figs. 148, 172, etc.). The vascular axis, of insignificant diameter
in proportion to the size of the stem (figs. 152, 153, 172, 181, A), must have
played a subordinate part, from a mechanical point of view, as compared
with the solid mass of wood of a Pine or an Oak.
• • • • •
Within the compass of a text-book it is impossible, even if it were
desirable, to include an account of the majority of the species of the widely
distributed Palaeozoic genus Lepidodendron. In spite of the great number of
known species of this common member of Carboniferous floras, our
knowledge of the type as a whole is deficient in many points, and such
information as we possess needs systematising and extending by
comparative treatment based on a re-examination of available data.
In order to appreciate the meaning of certain external features
characteristic of Lepidodendron stems it is essential to have some
knowledge of the internal structure.
A dual system of terminology has been unavoidably adopted for species
of Lepidodendron: the majority of specific names have been assigned to
fossils known only in the form of casts or impressions, while petrified
fragments, which unfortunately seldom show the surface-features, have
received another set of names. A glance at the older palaeobotanical
literature reveals the existence of several generic designations, which fuller
information has shown to have been applied to lepidodendroid shoots
deprived of some of their superficial tissues before fossilisation and
differing considerably in appearance from the more complete branches of
the same species[240]. It has in some instances been possible to correlate the
two sets of specimens, casts or impressions, showing external features, and
petrified fragments. We may reasonably expect that future discoveries will
enable us to piece together as definite specific types specimens at present
labelled with different names.
Page 128
A well-preserved leaf-cushion of a Lepidodendron—the most obvious
distinguishing feature of the genus—is rhomboidal or fusiform and
vertically elongated (fig. 146, C, E; fig. 185, C, D): in exceptional cases it
may reach a length of 8 cm. and a breadth of 2 cm. The cushion as a whole
represents a prominent portion of the stem or branch comparable with the
elevation on the twig of a Spruce Fir and the leaf-base of a Lycopodium (cf.
fig. 121, A, lower portion) which appears in a transverse section of a branch
as a rounded prominence (cf. Lycopodium, fig. 125, A and H). Disregarding
differences in detail, a typical Lepidodendron leaf-cushion is characterised
by a clearly defined smooth area often situated in the middle region (fig.
146, C, s). This is the leaf-scar or place of attachment of the base of the leaf
which was cut off by an absciss-layer while the branch was comparatively
young, as in recent forest trees and in some species of Ferns. On the leaf-
scar are three smaller scars or cicatricules, the central one is circular or
more or less triangular in outline, the two lateral scars being usually oval or
circular. The central pit marks the position of the single vascular bundle
which constituted the conducting tissue connecting the leaf with the main
vascular system of the stem. The two lateral scars (figs. 145, A, p; 146, C, s;
147, p) represent the exposed ends of two strands of tissue, the forked
branches of a strand which pass from the middle cortex of the stem into the
leaf; this is known as the parichnos, a name proposed by Professor Bertrand
in 1891[241].
The specimen shown in fig. 141 shows the linear leaves attached to their
respective cushions.
distinguishing feature of the genus—is rhomboidal or fusiform and
vertically elongated (fig. 146, C, E; fig. 185, C, D): in exceptional cases it
may reach a length of 8 cm. and a breadth of 2 cm. The cushion as a whole
represents a prominent portion of the stem or branch comparable with the
elevation on the twig of a Spruce Fir and the leaf-base of a Lycopodium (cf.
fig. 121, A, lower portion) which appears in a transverse section of a branch
as a rounded prominence (cf. Lycopodium, fig. 125, A and H). Disregarding
differences in detail, a typical Lepidodendron leaf-cushion is characterised
by a clearly defined smooth area often situated in the middle region (fig.
146, C, s). This is the leaf-scar or place of attachment of the base of the leaf
which was cut off by an absciss-layer while the branch was comparatively
young, as in recent forest trees and in some species of Ferns. On the leaf-
scar are three smaller scars or cicatricules, the central one is circular or
more or less triangular in outline, the two lateral scars being usually oval or
circular. The central pit marks the position of the single vascular bundle
which constituted the conducting tissue connecting the leaf with the main
vascular system of the stem. The two lateral scars (figs. 145, A, p; 146, C, s;
147, p) represent the exposed ends of two strands of tissue, the forked
branches of a strand which pass from the middle cortex of the stem into the
leaf; this is known as the parichnos, a name proposed by Professor Bertrand
in 1891[241].
The specimen shown in fig. 141 shows the linear leaves attached to their
respective cushions.
Page 129
Fig. 141. Lepidodendron Sternbergii. From a specimen in the British Museum (No. v. 1235)
from the Coal-Measures of Shropshire. (Nat. size.)
The lamina has a well-defined median keel on the lower surface and on
either side a groove in which sections of petrified leaves have demonstrated
the occurrence of stomata (cf. fig. 142).
ii. Leaves and Leaf-cushions.
All Lepidodendron leaves, so far as we know, possessed a single median
vein only. In some species, as for example in Lepidodendron longifolium
Brongn., they have the form of long and slender acicular needles very
similar to those of Pinus longifolium; in L. Sternbergii (fig. 141) they are
much broader and shorter. In external form as in internal structure it is often
impossible to distinguish between the leaves of Lepidodendron and
Sigillaria. The distinguishing features enumerated by the late M. Renault
cannot be employed, with any great degree of confidence, as diagnostic
characters. In transverse section the lamina of a Lepidodendron leaf
presents the same appearance as that of the Sigillarian leaves represented in
fig. 142. Near the base the free part of the leaf is usually sub-rhomboidal in
section with short lateral wings, a ventral keel and two stomatal grooves
from the Coal-Measures of Shropshire. (Nat. size.)
The lamina has a well-defined median keel on the lower surface and on
either side a groove in which sections of petrified leaves have demonstrated
the occurrence of stomata (cf. fig. 142).
ii. Leaves and Leaf-cushions.
All Lepidodendron leaves, so far as we know, possessed a single median
vein only. In some species, as for example in Lepidodendron longifolium
Brongn., they have the form of long and slender acicular needles very
similar to those of Pinus longifolium; in L. Sternbergii (fig. 141) they are
much broader and shorter. In external form as in internal structure it is often
impossible to distinguish between the leaves of Lepidodendron and
Sigillaria. The distinguishing features enumerated by the late M. Renault
cannot be employed, with any great degree of confidence, as diagnostic
characters. In transverse section the lamina of a Lepidodendron leaf
presents the same appearance as that of the Sigillarian leaves represented in
fig. 142. Near the base the free part of the leaf is usually sub-rhomboidal in
section with short lateral wings, a ventral keel and two stomatal grooves
Page 130
(fig. 142, A, B, g). The form and arrangement of stomata are shown in fig.
143, A, which was drawn from a piece of a leaf shown in surface-view in a
section lent to me by Professor Weiss. It should, however, be pointed out
that the leaf cannot be certainly identified with Lepidodendron rather than
with Sigillaria, but as the leaves of these two genera are constructed on the
same plan the identification is of secondary importance.
Fig. 142. Leaves of Sigillaria in transverse section.
A, A′. Section in the Manchester University Museum (Q. 631).
B, C. Sections in Dr Kidston’s Collection.
The single xylem bundle consists of primary tracheae only, at least in
such laminae as have been identified as Lepidodendroid. Surrounding the
xylem strand occur delicate parenchymatous cells in some cases
accompanied by darker and thicker-walled elements. As in Sigillaria, the
leaves of which are more fully described on page 210, a fairly broad sheath
of wider and shorter scalariform or spiral transfusion tracheids surrounds
143, A, which was drawn from a piece of a leaf shown in surface-view in a
section lent to me by Professor Weiss. It should, however, be pointed out
that the leaf cannot be certainly identified with Lepidodendron rather than
with Sigillaria, but as the leaves of these two genera are constructed on the
same plan the identification is of secondary importance.
Fig. 142. Leaves of Sigillaria in transverse section.
A, A′. Section in the Manchester University Museum (Q. 631).
B, C. Sections in Dr Kidston’s Collection.
The single xylem bundle consists of primary tracheae only, at least in
such laminae as have been identified as Lepidodendroid. Surrounding the
xylem strand occur delicate parenchymatous cells in some cases
accompanied by darker and thicker-walled elements. As in Sigillaria, the
leaves of which are more fully described on page 210, a fairly broad sheath
of wider and shorter scalariform or spiral transfusion tracheids surrounds
Page 131
the conducting strand (figs. 142, t; 143, B, C, t). As Renault shows in the
case of Lepidodendron esnostense[242], the small leaves of which are 1·5–2
mm. broad at the base and several centimetres long, the stomatal grooves
and keel die out towards the apex when the lamina assumes a more nearly
circular form (fig. 143, C).
Fig. 143.
A. Stomata in surface-view (Lepidodendron?). a, parenchyma; t, transfusion
tracheae; x, xylem. (Manchester University Collection R. 723).
B, C. Lepidodendron esnostense Ren. (After Renault.)
The area of the cushion excluding the leaf-scar is spoken of by some
writers as the field. Below the leaf-scar the kite-shaped cushion tapers to a
gradually narrowing basal position: in Lepidodendron Veltheimianum, a
species characteristic of Lower Carboniferous strata, it is seen to be
continuous, as a ridge with sloping sides, with a lower cushion (fig. 185).
Below a leaf-scar the cushion frequently shows a pair of oval areas on
which a fine pitting may be detected in well-preserved impressions, these
oval scars, as seen in fig. 185, D, are practically continuous at the upper end
with the parichnos scars on the leaf-scar area; this is explained by the fact
that these infra-foliar scars also owe their existence to patches of lacunar,
aerenchymatous tissue in close connexion with the parichnos[243].
case of Lepidodendron esnostense[242], the small leaves of which are 1·5–2
mm. broad at the base and several centimetres long, the stomatal grooves
and keel die out towards the apex when the lamina assumes a more nearly
circular form (fig. 143, C).
Fig. 143.
A. Stomata in surface-view (Lepidodendron?). a, parenchyma; t, transfusion
tracheae; x, xylem. (Manchester University Collection R. 723).
B, C. Lepidodendron esnostense Ren. (After Renault.)
The area of the cushion excluding the leaf-scar is spoken of by some
writers as the field. Below the leaf-scar the kite-shaped cushion tapers to a
gradually narrowing basal position: in Lepidodendron Veltheimianum, a
species characteristic of Lower Carboniferous strata, it is seen to be
continuous, as a ridge with sloping sides, with a lower cushion (fig. 185).
Below a leaf-scar the cushion frequently shows a pair of oval areas on
which a fine pitting may be detected in well-preserved impressions, these
oval scars, as seen in fig. 185, D, are practically continuous at the upper end
with the parichnos scars on the leaf-scar area; this is explained by the fact
that these infra-foliar scars also owe their existence to patches of lacunar,
aerenchymatous tissue in close connexion with the parichnos[243].
Page 132
Shortly before entering the base of the leaf-lamina the parichnos divides
into two arms which diverge in the outer cortical region right and left of the
vascular bundle, and passing obliquely upwards they come close to the
surface of the leaf-cushion just below the leaf-scar. The diagram—fig. 144,
B—shows a leaf-trace, lt, in the leaf-cushion, as seen in a diagrammatic
drawing of a vertical radial section of a stem, the dotted lines, p, p′, show
the two parichnos arms which are represented as impinging on the surface
of the leaf-cushion at p′, and then bending upwards to pass into the leaf-
base right and left of the vascular bundle or leaf-trace. For convenience the
arms of the parichnos are represented in one plane though actually in
different vertical planes.
Fig. 144, A, shows the difference between a view of the original surface
of a Lepidodendron, as at a, where a leaf-cushion with a leaf-scar is seen,
and a view of an impression representing the outer cortex, b, a short
distance below the surface. The surface b, in fig. 144, A, corresponds to the
face d-e in the diagrammatic longitudinal section fig. 144, B: the outline of
each cushion is clearly visible and in the centre is seen the leaf-trace, lt,
with its parichnos.
The surface-features, a (fig. 144, A), have been impressed on the rock, c,
(fig. 144, B) in which the specimen was entombed and by the removal of
the cast of the stem, that is the thickness b to e in fig. 144, B, the form of
the leaf-cushion is revealed. The presence of the two infra-foliar parichnos
scars at p′ (fig. 144, A) is explained by the diagram, fig. 144, B, p′.
The relation of the parichnos to the oval scars below a Lepidodendron
leaf-cushion has been worked out in detail by Weiss who shows that, at
least in some species, the two arms do not bend downwards as shown in the
diagram, fig. 144, B, but pursue a straight gradually ascending course as
seen in fig. 145, A. Just below the leaf-scar region of the cushion each arm
comes into association with a group of lacunar, aerenchymatous tissue, such
as occurs in the roots of certain Mangrove plants, and it is this aerenchyma
which is exposed on the two oval depressions below the leaf-scar. The
structure of this aerenchyma is shown in fig. 145, B; it consists in this
species (L. Hickii Wats.) of stellate cells which would constitute an efficient
aerating system. Probably, as Weiss suggests, these patches of aerenchyma
were originally covered by an epidermis provided with stomata, and it is
owing to the destruction of this superficial layer that the two oval scars
into two arms which diverge in the outer cortical region right and left of the
vascular bundle, and passing obliquely upwards they come close to the
surface of the leaf-cushion just below the leaf-scar. The diagram—fig. 144,
B—shows a leaf-trace, lt, in the leaf-cushion, as seen in a diagrammatic
drawing of a vertical radial section of a stem, the dotted lines, p, p′, show
the two parichnos arms which are represented as impinging on the surface
of the leaf-cushion at p′, and then bending upwards to pass into the leaf-
base right and left of the vascular bundle or leaf-trace. For convenience the
arms of the parichnos are represented in one plane though actually in
different vertical planes.
Fig. 144, A, shows the difference between a view of the original surface
of a Lepidodendron, as at a, where a leaf-cushion with a leaf-scar is seen,
and a view of an impression representing the outer cortex, b, a short
distance below the surface. The surface b, in fig. 144, A, corresponds to the
face d-e in the diagrammatic longitudinal section fig. 144, B: the outline of
each cushion is clearly visible and in the centre is seen the leaf-trace, lt,
with its parichnos.
The surface-features, a (fig. 144, A), have been impressed on the rock, c,
(fig. 144, B) in which the specimen was entombed and by the removal of
the cast of the stem, that is the thickness b to e in fig. 144, B, the form of
the leaf-cushion is revealed. The presence of the two infra-foliar parichnos
scars at p′ (fig. 144, A) is explained by the diagram, fig. 144, B, p′.
The relation of the parichnos to the oval scars below a Lepidodendron
leaf-cushion has been worked out in detail by Weiss who shows that, at
least in some species, the two arms do not bend downwards as shown in the
diagram, fig. 144, B, but pursue a straight gradually ascending course as
seen in fig. 145, A. Just below the leaf-scar region of the cushion each arm
comes into association with a group of lacunar, aerenchymatous tissue, such
as occurs in the roots of certain Mangrove plants, and it is this aerenchyma
which is exposed on the two oval depressions below the leaf-scar. The
structure of this aerenchyma is shown in fig. 145, B; it consists in this
species (L. Hickii Wats.) of stellate cells which would constitute an efficient
aerating system. Probably, as Weiss suggests, these patches of aerenchyma
were originally covered by an epidermis provided with stomata, and it is
owing to the destruction of this superficial layer that the two oval scars
Page 133
often form a prominent feature on Lepidodendron leaf-bases[244]. The
diagram reproduced in fig. 144, B, may be taken as practically correct, as
the patches of aerenchyma described by Weiss do not differ essentially from
the parichnos tissue.
Fig. 144. Lepidodendron Veltheimianum Sternb.
A. Leaf-cushion and leaf-scar seen in surface-view at a; on the rest of the specimen a
slightly lower surface is exposed. (After Stur.)
B. Diagrammatic longitudinal section to explain the differences between its two
surfaces a and b shown in fig. A.
The shaded portion c represents the rock matrix, the surfaces ab, ed, mark the
outer and inner edge of the outer portion of the bark of the Lepidodendron stem.
lt, leaf-trace; p, p′, parichnos.
diagram reproduced in fig. 144, B, may be taken as practically correct, as
the patches of aerenchyma described by Weiss do not differ essentially from
the parichnos tissue.
Fig. 144. Lepidodendron Veltheimianum Sternb.
A. Leaf-cushion and leaf-scar seen in surface-view at a; on the rest of the specimen a
slightly lower surface is exposed. (After Stur.)
B. Diagrammatic longitudinal section to explain the differences between its two
surfaces a and b shown in fig. A.
The shaded portion c represents the rock matrix, the surfaces ab, ed, mark the
outer and inner edge of the outer portion of the bark of the Lepidodendron stem.
lt, leaf-trace; p, p′, parichnos.
Page 134
Fig. 145.
A. Diagrammatic surface-view and longitudinal section of a Lepidodendron leaf-
cushion.
B. Aerenchyma below the leaf-scar. (After F. E. Weiss.)
The parichnos scars are shown on the leaf-scar and cushion in fig. 146,
C. In the lower leaf-cushion shown in fig. 146, E, the infra-foliar parichnos
scars, p, are clearly seen, but the preservation of the leaf-scar is not
sufficiently good to show them on that part of the fossil. In the upper
cushion (fig. 146, E) the position of the parichnos arms is shown on the
leaf-scar, but the infra-foliar parichnos scars are hidden by two small spiral
shells. The genus Spirorbis, to which these shells are referred, appears to
have persisted from the Silurian epoch to the present day. The
comparatively frequent occurrence of Spirorbis shells on the leaves and
other parts of Palaeozoic plants, has recently been dealt with in a paper by
Barrois[245] who discusses in detail the habitats of these small animals from
the point of view of the conditions under which the plants were preserved.
A. Diagrammatic surface-view and longitudinal section of a Lepidodendron leaf-
cushion.
B. Aerenchyma below the leaf-scar. (After F. E. Weiss.)
The parichnos scars are shown on the leaf-scar and cushion in fig. 146,
C. In the lower leaf-cushion shown in fig. 146, E, the infra-foliar parichnos
scars, p, are clearly seen, but the preservation of the leaf-scar is not
sufficiently good to show them on that part of the fossil. In the upper
cushion (fig. 146, E) the position of the parichnos arms is shown on the
leaf-scar, but the infra-foliar parichnos scars are hidden by two small spiral
shells. The genus Spirorbis, to which these shells are referred, appears to
have persisted from the Silurian epoch to the present day. The
comparatively frequent occurrence of Spirorbis shells on the leaves and
other parts of Palaeozoic plants, has recently been dealt with in a paper by
Barrois[245] who discusses in detail the habitats of these small animals from
the point of view of the conditions under which the plants were preserved.
Page 135
In a note by Malaquin appended to Barrois’ paper the belief is expressed
that Spirorbis lived on pieces of Palaeozoic plants which lay under water.
The fact that with one exception all the Spirorbis shells on the specimen
of Lepidodendron, of which two leaf-cushions are shown in fig. 146, E,
occur on the large parichnos scars on the cheeks of the cushions, suggests
the possibility that the escape of gases from the parichnos tissue may have
rendered the position attractive to the Spirorbis. It can hardly be accidental
that the shells occur on the parichnos strands. This fact recalls the view held
by Binney[246] and accepted with favour by Darwin[247] that Lepidodendron
and other coal-forest trees may have lived with the lower parts of the stems
in sea water.
Above the leaf-scar is a fairly deep triangular or crescentic pit (fig. 146,
C, l) known as the ligular pit from the occurrence on younger shoots of a
delicate organ like the ligule of Isoetes (fig. 132) embedded in a depression
in the upper part of the leaf-cushion. The ligule was first figured in
Lepidodendron by Solms-Laubach[248] and described in English material by
Williamson under the name of the adenoid organ[249].
In some Lepidodendron stems a second triangular depression may occur
above the ligular pit, the meaning of which is not clear: this has been called
the triangulum by Potonié[250]. Stur[251] suggested that it may represent the
position occupied by a sporangium in Lepidodendron cones.
It is important to remember that as a branch increases in girth the leaf-
cushions are capable of only a certain amount of growth: when the limit is
reached they are stretched farther apart and thus the narrow groove which
separates them is converted in older stems into a comparatively broad and
flat channel, thus altering the surface characters.
that Spirorbis lived on pieces of Palaeozoic plants which lay under water.
The fact that with one exception all the Spirorbis shells on the specimen
of Lepidodendron, of which two leaf-cushions are shown in fig. 146, E,
occur on the large parichnos scars on the cheeks of the cushions, suggests
the possibility that the escape of gases from the parichnos tissue may have
rendered the position attractive to the Spirorbis. It can hardly be accidental
that the shells occur on the parichnos strands. This fact recalls the view held
by Binney[246] and accepted with favour by Darwin[247] that Lepidodendron
and other coal-forest trees may have lived with the lower parts of the stems
in sea water.
Above the leaf-scar is a fairly deep triangular or crescentic pit (fig. 146,
C, l) known as the ligular pit from the occurrence on younger shoots of a
delicate organ like the ligule of Isoetes (fig. 132) embedded in a depression
in the upper part of the leaf-cushion. The ligule was first figured in
Lepidodendron by Solms-Laubach[248] and described in English material by
Williamson under the name of the adenoid organ[249].
In some Lepidodendron stems a second triangular depression may occur
above the ligular pit, the meaning of which is not clear: this has been called
the triangulum by Potonié[250]. Stur[251] suggested that it may represent the
position occupied by a sporangium in Lepidodendron cones.
It is important to remember that as a branch increases in girth the leaf-
cushions are capable of only a certain amount of growth: when the limit is
reached they are stretched farther apart and thus the narrow groove which
separates them is converted in older stems into a comparatively broad and
flat channel, thus altering the surface characters.
Page 136
Fig. 146. Lepidophloios and Lepidodendron leaf-cushions.
A, B, D, F, G, H, I. Lepidophloios. (Fig. A should be reversed.)
C, E. Lepidodendron aculeatum.
A, B. From a specimen in the Sedgwick Museum, Cambridge (leaf-cushion 3 cm. broad).
C. From a specimen in the Sedgwick Museum, Cambridge (leaf-cushion 4 cm. long).
D. From a section in the Cambridge Botany School Collection.
E. From a specimen in the Bunbury Collection, Cambridge Botany School, showing
Spirorbis shells (leaf-cushion 2 cm. long).
F. From a section in the Williamson Collection, British Museum No. 1, 973.
G, H, I. From sections in the Cambridge Botany School Collection.
Another feature worthy of notice in reference to the leaf-cushions of
Lepidodendron is the occurrence in rare instances of alternate zones of
A, B, D, F, G, H, I. Lepidophloios. (Fig. A should be reversed.)
C, E. Lepidodendron aculeatum.
A, B. From a specimen in the Sedgwick Museum, Cambridge (leaf-cushion 3 cm. broad).
C. From a specimen in the Sedgwick Museum, Cambridge (leaf-cushion 4 cm. long).
D. From a section in the Cambridge Botany School Collection.
E. From a specimen in the Bunbury Collection, Cambridge Botany School, showing
Spirorbis shells (leaf-cushion 2 cm. long).
F. From a section in the Williamson Collection, British Museum No. 1, 973.
G, H, I. From sections in the Cambridge Botany School Collection.
Another feature worthy of notice in reference to the leaf-cushions of
Lepidodendron is the occurrence in rare instances of alternate zones of
Page 137
larger and smaller cushions. This variation in the size of the leaf-cushions is
by no means uncommon in the closely allied genus Sigillaria; in
Lepidodendron it has been described by Potonié[252] in L. volkmannianum
and more recently by Mr Leslie and myself[253] in a South African species L.
vereenigense.
Owing to the natural exfoliation of the superficial layers of the outer bark
at a certain stage in the growth of the plant, or in some instances no doubt
as the result of post-mortem decay, which destroys the delicate cells of the
meristematic zone in the outer cortex, isolated leaf-cushions and strips of
the external surface are occasionally met with as carbonised impressions.
The appearance presented by a Lepidodendron stem which has been
deprived of its superficial tissues may be dealt with more intelligibly after
we have become familiar with the anatomical characters.
iii. Lepidophloios.
Before proceeding further with the genus Lepidodendron a short account
may be intercalated of the external features of a lepidodendroid type of
stem which it is customary to describe under a distinct generic title
Lepidophloios. This name is convenient for diagnostic purposes though it
seems clear that apart from the form of the leaf-cushion (fig. 146, A) we are
at present unable to recognise any well-defined differences between the two
forms Lepidodendron and Lepidophloios. For general purposes the name
Lepidodendron will be used as including plants possessing leaf-cushions of
the type already described as well as those with the Lepidophloios form of
cushion.
The generic name Lepidophloios was first used by Sternberg[254] for a
Carboniferous species which he had previously described as Lepidodendron
laricinum. In 1845 Corda[255] instituted the name Lomatophloios for
specimens possessing the same external characters as those for which
Sternberg had chosen the name Lepidophloios. The leaf-cushions of
Lepidophloios differ from those of the true Lepidodendron in their
relatively greater lateral extension (cf. fig. 146, A and C), in their imbricate
arrangement and in bearing the leaf, or leaf-scar, at the summit. In some
species referred to Lepidophloios the cushions are however vertically
elongated and in this respect similar to those of Lepidodendron: an example
by no means uncommon in the closely allied genus Sigillaria; in
Lepidodendron it has been described by Potonié[252] in L. volkmannianum
and more recently by Mr Leslie and myself[253] in a South African species L.
vereenigense.
Owing to the natural exfoliation of the superficial layers of the outer bark
at a certain stage in the growth of the plant, or in some instances no doubt
as the result of post-mortem decay, which destroys the delicate cells of the
meristematic zone in the outer cortex, isolated leaf-cushions and strips of
the external surface are occasionally met with as carbonised impressions.
The appearance presented by a Lepidodendron stem which has been
deprived of its superficial tissues may be dealt with more intelligibly after
we have become familiar with the anatomical characters.
iii. Lepidophloios.
Before proceeding further with the genus Lepidodendron a short account
may be intercalated of the external features of a lepidodendroid type of
stem which it is customary to describe under a distinct generic title
Lepidophloios. This name is convenient for diagnostic purposes though it
seems clear that apart from the form of the leaf-cushion (fig. 146, A) we are
at present unable to recognise any well-defined differences between the two
forms Lepidodendron and Lepidophloios. For general purposes the name
Lepidodendron will be used as including plants possessing leaf-cushions of
the type already described as well as those with the Lepidophloios form of
cushion.
The generic name Lepidophloios was first used by Sternberg[254] for a
Carboniferous species which he had previously described as Lepidodendron
laricinum. In 1845 Corda[255] instituted the name Lomatophloios for
specimens possessing the same external characters as those for which
Sternberg had chosen the name Lepidophloios. The leaf-cushions of
Lepidophloios differ from those of the true Lepidodendron in their
relatively greater lateral extension (cf. fig. 146, A and C), in their imbricate
arrangement and in bearing the leaf, or leaf-scar, at the summit. In some
species referred to Lepidophloios the cushions are however vertically
elongated and in this respect similar to those of Lepidodendron: an example
Page 138
of this type is afforded by Lepidophloios Dessorti a French species
described by Zeiller[256]. In younger branches the cushions may be directed
upwards having the leaf-scar at the top; but in the majority of specimens the
cushions are deflexed as in figs. 146, D; 160, A. The shoot of Lycopodium
dichotomum shown in fig. 121, B, with the leaves in the reversed position
bears a close resemblance to a branch of Lepidophloios.
The photograph of Lepidophloios scoticus Kidst.[257] reproduced in fig.
160, A, illustrates the dichotomous branching of the stem and the form of
the cushions with the leaf-scars pointing downwards. In the fertile branch of
the same species shown in fig. 160, B, the leaf-scars face upwards.
In most species the cushions are simply convex without a median keel,
but in some cases a median ridge divides the cushion into two cheeks as in
the genus Lepidodendron. The leaf-scar bears three small scars, the larger
median scar marking the position of the leaf-trace, while the lateral scars
are formed by the two arms of the parichnos: in some examples of deflexed
cushions, though not in all, a ligular pit occurs on the cushion a short
distance above the leaf-scar.
The drawing reproduced in fig. 146, A, showing the leaf-scar on the
upper edge of the cushion should have been reversed with the leaf-scars
pointing downwards. This figure represents part of the surface of a
specimen consisting of the outer cortex of a stem with leaf-cushions 3 cm.
broad. The thickness of this specimen is 4 cm.: a section through the line ab
is represented in fig. 146, D (reproduced in the correct position, with the
leaf-scars, sc, pointing downwards): internal to the cushions is a band of
secondary cortex (the shaded strip on the outer edge of the section) which
was formed on the outside of the phellogen. The phellogen is a cylinder of
actively dividing cells in the outer part of the cortex of the stem, often
spoken of as the cork-cambium or cortical meristem, which produces a
considerable amount of secondary cortical tissue on its inner face and a
much smaller amount towards the stem surface. This delicate cylinder
frequently forms a natural line of separation between the outer shell of bark
and the rest of the stem. In the specimen before us, the thin-walled cells of
the phellogen were ruptured before petrification and the outer shell of bark
was thus separated as a hollow cylinder from the rest of the stem: this
cylinder was then flattened, the two inner surfaces coming into contact. Fig.
described by Zeiller[256]. In younger branches the cushions may be directed
upwards having the leaf-scar at the top; but in the majority of specimens the
cushions are deflexed as in figs. 146, D; 160, A. The shoot of Lycopodium
dichotomum shown in fig. 121, B, with the leaves in the reversed position
bears a close resemblance to a branch of Lepidophloios.
The photograph of Lepidophloios scoticus Kidst.[257] reproduced in fig.
160, A, illustrates the dichotomous branching of the stem and the form of
the cushions with the leaf-scars pointing downwards. In the fertile branch of
the same species shown in fig. 160, B, the leaf-scars face upwards.
In most species the cushions are simply convex without a median keel,
but in some cases a median ridge divides the cushion into two cheeks as in
the genus Lepidodendron. The leaf-scar bears three small scars, the larger
median scar marking the position of the leaf-trace, while the lateral scars
are formed by the two arms of the parichnos: in some examples of deflexed
cushions, though not in all, a ligular pit occurs on the cushion a short
distance above the leaf-scar.
The drawing reproduced in fig. 146, A, showing the leaf-scar on the
upper edge of the cushion should have been reversed with the leaf-scars
pointing downwards. This figure represents part of the surface of a
specimen consisting of the outer cortex of a stem with leaf-cushions 3 cm.
broad. The thickness of this specimen is 4 cm.: a section through the line ab
is represented in fig. 146, D (reproduced in the correct position, with the
leaf-scars, sc, pointing downwards): internal to the cushions is a band of
secondary cortex (the shaded strip on the outer edge of the section) which
was formed on the outside of the phellogen. The phellogen is a cylinder of
actively dividing cells in the outer part of the cortex of the stem, often
spoken of as the cork-cambium or cortical meristem, which produces a
considerable amount of secondary cortical tissue on its inner face and a
much smaller amount towards the stem surface. This delicate cylinder
frequently forms a natural line of separation between the outer shell of bark
and the rest of the stem. In the specimen before us, the thin-walled cells of
the phellogen were ruptured before petrification and the outer shell of bark
was thus separated as a hollow cylinder from the rest of the stem: this
cylinder was then flattened, the two inner surfaces coming into contact. Fig.
Page 139
146, D, represents a section of one half of the thickness of the flattened
shell.
This separation of the outer cortex, and its preservation apart from the
rest of the stem, is of frequent occurrence in fossil lycopodiaceous stems.
The flattened outer cortical shell of a Lepidophloios, specifically identical
with that shown in fig. 146, A and D, was erroneously described by Dr C. E.
Weiss in 1881 as a large lepidodendroid cone[258].
Fig. 146, B, affords a view of the inner face of the specimen of which the
outer surface is seen in fig. 146, A: the surface shown in the lower part of
the drawing, on which the boundaries of the cushions are represented by a
reticulum, corresponds to the inner edge of the strip of secondary cortical
tissue represented by the vertically shaded band in fig. 146, D.
The shaded surface in fig. 146, B, represents a slightly deeper level in the
stem which corresponds to the outer edge of the vertically shaded band of
fig. 146, D: the narrow tapered ridges (fig. 146, B) represent the leaf-traces
passing through the secondary cortex, and the fine vertical shading indicates
the elongated elements of which this strip of secondary cortex is composed.
In the longitudinal section diagrammatically reproduced in fig. 146, D,
cut along the line ab of fig. 146, A, the parenchymatous tissue of the stout
cushions has been partially destroyed, as at a; at s is seen the section of a
Stigmarian rootlet which has found its way into the interior of a cushion.
Each leaf-trace is accompanied by a parichnos strand as in the true
Lepidodendron; at the base of the leaf-cushion the parichnos branches into
two arms which diverge slightly right and left of the leaf-trace, finally
entering the base of the leaf lamina as two lateral strands (fig. 147, p). At
one point in fig. 146, D the section has shaved a leaf-trace represented by a
black patch resting on the parichnos just above the line ef, but it passes
through one of the parichnos arms p′ which debouches on to the leaf-scar sc
at p. Had the section been cut along the line cd of fig. 146, A the leaf-trace
would have been seen in a position similar to that occupied by the parichnos
p′ in fig. 146, D.
shell.
This separation of the outer cortex, and its preservation apart from the
rest of the stem, is of frequent occurrence in fossil lycopodiaceous stems.
The flattened outer cortical shell of a Lepidophloios, specifically identical
with that shown in fig. 146, A and D, was erroneously described by Dr C. E.
Weiss in 1881 as a large lepidodendroid cone[258].
Fig. 146, B, affords a view of the inner face of the specimen of which the
outer surface is seen in fig. 146, A: the surface shown in the lower part of
the drawing, on which the boundaries of the cushions are represented by a
reticulum, corresponds to the inner edge of the strip of secondary cortical
tissue represented by the vertically shaded band in fig. 146, D.
The shaded surface in fig. 146, B, represents a slightly deeper level in the
stem which corresponds to the outer edge of the vertically shaded band of
fig. 146, D: the narrow tapered ridges (fig. 146, B) represent the leaf-traces
passing through the secondary cortex, and the fine vertical shading indicates
the elongated elements of which this strip of secondary cortex is composed.
In the longitudinal section diagrammatically reproduced in fig. 146, D,
cut along the line ab of fig. 146, A, the parenchymatous tissue of the stout
cushions has been partially destroyed, as at a; at s is seen the section of a
Stigmarian rootlet which has found its way into the interior of a cushion.
Each leaf-trace is accompanied by a parichnos strand as in the true
Lepidodendron; at the base of the leaf-cushion the parichnos branches into
two arms which diverge slightly right and left of the leaf-trace, finally
entering the base of the leaf lamina as two lateral strands (fig. 147, p). At
one point in fig. 146, D the section has shaved a leaf-trace represented by a
black patch resting on the parichnos just above the line ef, but it passes
through one of the parichnos arms p′ which debouches on to the leaf-scar sc
at p. Had the section been cut along the line cd of fig. 146, A the leaf-trace
would have been seen in a position similar to that occupied by the parichnos
p′ in fig. 146, D.
Page 140
Fig. 147. Lepidophloios leaf-cushion in tangential section. (From a section in the Williamson
Collection, British Museum, No. 1973.)
Fig. 147, A, affords a good example of a tangential section through a
Lepidophloios leaf-cushion, 1 cm. broad, like that represented in fig. 146,
A, showing the vascular bundle lt, the two parichnos strands, p, composed
of large thin-walled cells (cf. Isoetes, fig. 133, H, I), and the ligular pit near
the upper edge of the section enclosing the shrunken remains of the ligule
(fig. 147, B, l).
LEPIDODENDRON
Fig. 147, B, shows the form of the tangentially elongated leaf-cushions of
Lepidophloios and their spiral disposition.
Collection, British Museum, No. 1973.)
Fig. 147, A, affords a good example of a tangential section through a
Lepidophloios leaf-cushion, 1 cm. broad, like that represented in fig. 146,
A, showing the vascular bundle lt, the two parichnos strands, p, composed
of large thin-walled cells (cf. Isoetes, fig. 133, H, I), and the ligular pit near
the upper edge of the section enclosing the shrunken remains of the ligule
(fig. 147, B, l).
LEPIDODENDRON
Fig. 147, B, shows the form of the tangentially elongated leaf-cushions of
Lepidophloios and their spiral disposition.
Page 141
Fig. 146, F, represents a section similar to that shown in figs. 147, A and
B, but in this case the leaf-trace, lt, and the parichnos strands, p, lie in a
cavity formed by the destruction of some of the leaf-cushion tissue. It is
worthy of notice that the parichnos cells have resisted decay more
successfully than the adjacent tissue of the cushion.
The diagrammatic sketches reproduced in fig. 146, H and I, were made
from a transverse section similar to one originally figured by
Williamson[259]: fig. 146, H, corresponding in position to the line gh in fig.
146, A, passes through the ligular pit, l, and cuts across the parichnos in the
act of branching; the leaf-trace passes outwards beyond the Y-shaped
parichnos strand. In the other section, fig. 146, I, the parichnos is shown in
a horizontal plane and the leaf-trace, lt, appears in oblique transverse
section. In both sections and in fig. 146, G the shaded band at the base
represents the secondary cortical tissue external to the phellogen.
The transverse section represented in fig. 146, G, shows in the left-hand
cushion, a, the exit of the two parichnos arms and the leaf-trace between
them: it illustrates also the various forms assumed by lepidodendroid leaf-
cushions when cut across at different levels.
iv. The Anatomy of Lepidodendron vasculare Binney[260].
Figs. 148–155, 168, A.
In the earlier literature dealing with the anatomy of Lepidodendron and
Sigillaria the presence or absence of secondary vascular tissue was made
the criterion of generic distinction and the distinguishing feature between
the classes Pteridophytes and Gymnosperms, Lepidodendron being
relegated to the former class because it was supposed to have no power of
forming secondary wood, while Sigillaria, characterised by a considerable
development of such tissue, was classed by Brongniart and afterwards by
Renault as a Gymnosperm. Binney[261] in 1865 recognised that the two types
of stem pass into one another, but it was Williamson[262] who provided
complete demonstration of the fallacy of the Brongniartian view.
These two undoubted Pteridophytes agree very closely in anatomical
structure and both are now recognised as arborescent genera of
Lycopodiaceous plants. In a paper published by Lomax and Weiss in
1905[263] a specimen is described from the Coal-Measures of Huddersfield,
B, but in this case the leaf-trace, lt, and the parichnos strands, p, lie in a
cavity formed by the destruction of some of the leaf-cushion tissue. It is
worthy of notice that the parichnos cells have resisted decay more
successfully than the adjacent tissue of the cushion.
The diagrammatic sketches reproduced in fig. 146, H and I, were made
from a transverse section similar to one originally figured by
Williamson[259]: fig. 146, H, corresponding in position to the line gh in fig.
146, A, passes through the ligular pit, l, and cuts across the parichnos in the
act of branching; the leaf-trace passes outwards beyond the Y-shaped
parichnos strand. In the other section, fig. 146, I, the parichnos is shown in
a horizontal plane and the leaf-trace, lt, appears in oblique transverse
section. In both sections and in fig. 146, G the shaded band at the base
represents the secondary cortical tissue external to the phellogen.
The transverse section represented in fig. 146, G, shows in the left-hand
cushion, a, the exit of the two parichnos arms and the leaf-trace between
them: it illustrates also the various forms assumed by lepidodendroid leaf-
cushions when cut across at different levels.
iv. The Anatomy of Lepidodendron vasculare Binney[260].
Figs. 148–155, 168, A.
In the earlier literature dealing with the anatomy of Lepidodendron and
Sigillaria the presence or absence of secondary vascular tissue was made
the criterion of generic distinction and the distinguishing feature between
the classes Pteridophytes and Gymnosperms, Lepidodendron being
relegated to the former class because it was supposed to have no power of
forming secondary wood, while Sigillaria, characterised by a considerable
development of such tissue, was classed by Brongniart and afterwards by
Renault as a Gymnosperm. Binney[261] in 1865 recognised that the two types
of stem pass into one another, but it was Williamson[262] who provided
complete demonstration of the fallacy of the Brongniartian view.
These two undoubted Pteridophytes agree very closely in anatomical
structure and both are now recognised as arborescent genera of
Lycopodiaceous plants. In a paper published by Lomax and Weiss in
1905[263] a specimen is described from the Coal-Measures of Huddersfield,
Page 142
in which a decorticated stem with the anatomical characters of Binney’s
Sigillaria vascularis gives off a branch having the anatomical structure
which it has been customary to associate with the species Lepidodendron
selaginoides, so-called by Sternberg and founded by him on impressions
showing well-preserved external characters.
In 1862 Binney[264] described petrified specimens of vegetative shoots
from the Lower Coal-Measures of Lancashire under the names Sigillaria
vascularis and Lepidodendron vasculare. These were afterwards recognised
as different states of the same species. A few years after the publication of
Binney’s paper Carruthers[265] identified Binney’s species Lepidodendron
vasculare with Sternberg’s L. selaginoides. The evidence on which this
identification rests has not been stated, but many writers have retained this
specific designation for the well-defined type of anatomical structure first
described by Binney as L. vasculare. The use of the specific name
selaginoides is, however, open to objection. The species Lepidodendron
selaginoides, as pointed out by Kidston[266], is probably identical with the
plant which Brongniart had named L. Sternbergii before the institution of
Sternberg’s species, and we are not in possession of convincing evidence as
to the connection of L. Sternbergii (= L. selaginoides) with specimens
possessing the anatomy of Binney’s type. Binney’s designation is therefore
retained for the anatomical type described in the following pages[267].
The most detailed account hitherto published of the anatomy of
Lepidodendron vasculare is that by the late M. Hovelacque[268], based on
material from the Lower Coal-Measures of England.
Sigillaria vascularis gives off a branch having the anatomical structure
which it has been customary to associate with the species Lepidodendron
selaginoides, so-called by Sternberg and founded by him on impressions
showing well-preserved external characters.
In 1862 Binney[264] described petrified specimens of vegetative shoots
from the Lower Coal-Measures of Lancashire under the names Sigillaria
vascularis and Lepidodendron vasculare. These were afterwards recognised
as different states of the same species. A few years after the publication of
Binney’s paper Carruthers[265] identified Binney’s species Lepidodendron
vasculare with Sternberg’s L. selaginoides. The evidence on which this
identification rests has not been stated, but many writers have retained this
specific designation for the well-defined type of anatomical structure first
described by Binney as L. vasculare. The use of the specific name
selaginoides is, however, open to objection. The species Lepidodendron
selaginoides, as pointed out by Kidston[266], is probably identical with the
plant which Brongniart had named L. Sternbergii before the institution of
Sternberg’s species, and we are not in possession of convincing evidence as
to the connection of L. Sternbergii (= L. selaginoides) with specimens
possessing the anatomy of Binney’s type. Binney’s designation is therefore
retained for the anatomical type described in the following pages[267].
The most detailed account hitherto published of the anatomy of
Lepidodendron vasculare is that by the late M. Hovelacque[268], based on
material from the Lower Coal-Measures of England.
Page 143
Fig. 148. Lepidodendron vasculare Binney.
A. Transverse section. (Based on a section 2·5 cm. in diameter, in the Cambridge
Botany School Collection.)
B. Longitudinal section. (Drawn from a section in Dr Kidston’s Collection.)
The small shoot, represented somewhat diagrammatically in fig. 148, A,
illustrates the anatomical features of a typical example of the species: the
shoot has a diameter of 2·5 cm. and its central cylinder (x-sc) is 2·5 mm. in
width.
Noticeable features are (i) the small size of the central cylinder (or stele)
in proportion to the diameter of the branch, (ii) the production at a
comparatively early stage of growth of a zone of secondary wood, x2, which
A. Transverse section. (Based on a section 2·5 cm. in diameter, in the Cambridge
Botany School Collection.)
B. Longitudinal section. (Drawn from a section in Dr Kidston’s Collection.)
The small shoot, represented somewhat diagrammatically in fig. 148, A,
illustrates the anatomical features of a typical example of the species: the
shoot has a diameter of 2·5 cm. and its central cylinder (x-sc) is 2·5 mm. in
width.
Noticeable features are (i) the small size of the central cylinder (or stele)
in proportion to the diameter of the branch, (ii) the production at a
comparatively early stage of growth of a zone of secondary wood, x2, which
Page 144
gradually assumes the form of a complete cylinder of unequal breadth,
surrounding the primary xylem, x, (iii) the formation of a secondary cortical
tissue by a meristematic cylinder (phellogen, pl) situated close to the leaf-
cushion region of the outer cortex. On the outer edge the stele consists of
narrow tracheae some of which show in longitudinal section the spiral form
of thickening characteristic of most protoxylem elements: towards the
centre of the stele the diameter of the tracheae gradually increases and
parenchymatous cells become associated with the elongated scalariform
elements. In the central region the stele is composed of parenchymatous
tissue arranged in vertical series of short cells, interspersed with short
tracheae distinguished by the greater thickness of their walls and by their
scalariform and reticulate thickening bands. Some of these short tracheae
are shown in vertical section in fig. 149, B: the fine and broken lines
connecting adjacent thickening bands probably represent the remains of the
original wall. These delicate bands, which have been figured in various
species of lepidodendroid plants[269], are worthy of notice in connexion with
the recent work of Mr Gwynne-Vaughan[270] who has shown that in many
recent ferns the scalariform bands in the xylem elements are not connected
by a thin pit-closing membrane, but are separated from one another by open
spaces. In the Lepidodendron tracheae we seem to have a stage in which the
intervening membrane is in process of absorption. It is, however, possible
that the threads may be the result of contraction and splitting of the
membrane during drying or decay.
surrounding the primary xylem, x, (iii) the formation of a secondary cortical
tissue by a meristematic cylinder (phellogen, pl) situated close to the leaf-
cushion region of the outer cortex. On the outer edge the stele consists of
narrow tracheae some of which show in longitudinal section the spiral form
of thickening characteristic of most protoxylem elements: towards the
centre of the stele the diameter of the tracheae gradually increases and
parenchymatous cells become associated with the elongated scalariform
elements. In the central region the stele is composed of parenchymatous
tissue arranged in vertical series of short cells, interspersed with short
tracheae distinguished by the greater thickness of their walls and by their
scalariform and reticulate thickening bands. Some of these short tracheae
are shown in vertical section in fig. 149, B: the fine and broken lines
connecting adjacent thickening bands probably represent the remains of the
original wall. These delicate bands, which have been figured in various
species of lepidodendroid plants[269], are worthy of notice in connexion with
the recent work of Mr Gwynne-Vaughan[270] who has shown that in many
recent ferns the scalariform bands in the xylem elements are not connected
by a thin pit-closing membrane, but are separated from one another by open
spaces. In the Lepidodendron tracheae we seem to have a stage in which the
intervening membrane is in process of absorption. It is, however, possible
that the threads may be the result of contraction and splitting of the
membrane during drying or decay.
Page 145
Fig. 149. Lepidodendron vasculare. a, immature tracheae; m, meristem; mr, medullary ray;
x, xylem.
A. Longitudinal section through the edge of the secondary wood.
B. Short tracheae in the centre of the stele. (From a specimen from the Halifax Hard
bed in Dr Kidston’s Collection.)
The stele of Lepidodendron vasculare, before the addition of any
secondary xylem, may be described as a protostele, a term originally
proposed by Professor Jeffrey[271], in which the central part of the
conducting strand of xylem elements has been converted into rows of
parenchyma and short tracheids, the latter being better adapted to storage
than to conduction. It is probable that this type of stelar anatomy, which
distinguishes L. vasculare from other species, represents a comparatively
primitive arrangement forming a transition between the stele of L.
esnostense, which consists of a solid rod of tracheids, and the stele of L.
Harcourtii (fig. 179, A) and other species in which the xylem forms a
cylinder enclosing a large parenchymatous pith.
Parenchymatous cells occur in contact with the outer edge of the xylem-
cylinder some of which are distinguished by an irregular reticulate pitting.
The tangential section represented in fig. 148, B, illustrates the appearance
of a shoot of L. vasculare in which no secondary xylem is present: the
central strand of tissue consists of the parenchyma abutting on the xylem
with several leaf-traces (lt) passing upwards in an almost vertical course
from the outer edge of the stele.
x, xylem.
A. Longitudinal section through the edge of the secondary wood.
B. Short tracheae in the centre of the stele. (From a specimen from the Halifax Hard
bed in Dr Kidston’s Collection.)
The stele of Lepidodendron vasculare, before the addition of any
secondary xylem, may be described as a protostele, a term originally
proposed by Professor Jeffrey[271], in which the central part of the
conducting strand of xylem elements has been converted into rows of
parenchyma and short tracheids, the latter being better adapted to storage
than to conduction. It is probable that this type of stelar anatomy, which
distinguishes L. vasculare from other species, represents a comparatively
primitive arrangement forming a transition between the stele of L.
esnostense, which consists of a solid rod of tracheids, and the stele of L.
Harcourtii (fig. 179, A) and other species in which the xylem forms a
cylinder enclosing a large parenchymatous pith.
Parenchymatous cells occur in contact with the outer edge of the xylem-
cylinder some of which are distinguished by an irregular reticulate pitting.
The tangential section represented in fig. 148, B, illustrates the appearance
of a shoot of L. vasculare in which no secondary xylem is present: the
central strand of tissue consists of the parenchyma abutting on the xylem
with several leaf-traces (lt) passing upwards in an almost vertical course
from the outer edge of the stele.
Page 146
The secondary xylem (fig. 148, A, x2) consists of radially arranged
scalariform tracheae with associated rows of parenchymatous cells which
form medullary rays (fig. 149, mr). Leaf-traces pass through the medullary
rays in the secondary xylem cylinder in a direction at right angles to the
primary xylem stele from which they are given off, but at the outer edge of
the secondary xylem they bend suddenly upwards and for a time follow a
steep and almost vertical course.
In well-preserved longitudinal sections the outermost secondary xylem
tracheae are seen to be succeeded by a few narrow and vertically elongated
elements (fig. 149, A, a), which represent young unlignified tracheae: these
are followed by shorter parenchymatous cells (m) forming part of a
meristematic zone from which the secondary xylem receives additions.
Returning to fig. 148, A; the zone of secondary wood, x2, composed of
scalariform tracheids and medullary rays, is succeeded by a few layers of
parenchymatous cells and beyond this is a broader zone, sc, to which the
term secretory zone has been applied[272]; this is made up of small
parenchymatous cells varying in size and of larger spaces which appear to
have been formed by the disorganisation of thin-walled elements. The
whole zone presents a characteristic appearance due to the association of
small cells, large clear spaces, and a certain amount of dark-coloured
material suggestive of tissue disorganisation and secreted products. The
anatomical characters of the secretory zone are shown in the photograph,
fig. 168, A, sc. Several leaf-traces are seen in transverse section in the
secretory zone (black dots in fig. 148, A, sc; fig. 154, C, lt): each trace
consists of a strand of narrow tracheae accompanied by a few encircling
layers of small parenchymatous cells. As a trace continues its steeply
ascending course through the secretory zone, it becomes associated with a
strand of that tissue and assumes the form of a collateral vascular bundle,
the outer part of which does not consist of typical phloem but of shorter
elements derived from the secretory zone. Beyond the secretory zone we
find a more homogeneous tissue composed of parenchymatous elements
slightly extended tangentially (figs. 148, A, c1; fig. 168, A, c); this is spoken
of as the inner cortical region. In the great majority of sections of L.
vasculare as of other species of the genus, the broader middle cortex (fig.
148, c2) is occupied by mineral matter, introduced subsequent to decay of
the tissue; or it is represented by patches of delicate tissue composed of
scalariform tracheae with associated rows of parenchymatous cells which
form medullary rays (fig. 149, mr). Leaf-traces pass through the medullary
rays in the secondary xylem cylinder in a direction at right angles to the
primary xylem stele from which they are given off, but at the outer edge of
the secondary xylem they bend suddenly upwards and for a time follow a
steep and almost vertical course.
In well-preserved longitudinal sections the outermost secondary xylem
tracheae are seen to be succeeded by a few narrow and vertically elongated
elements (fig. 149, A, a), which represent young unlignified tracheae: these
are followed by shorter parenchymatous cells (m) forming part of a
meristematic zone from which the secondary xylem receives additions.
Returning to fig. 148, A; the zone of secondary wood, x2, composed of
scalariform tracheids and medullary rays, is succeeded by a few layers of
parenchymatous cells and beyond this is a broader zone, sc, to which the
term secretory zone has been applied[272]; this is made up of small
parenchymatous cells varying in size and of larger spaces which appear to
have been formed by the disorganisation of thin-walled elements. The
whole zone presents a characteristic appearance due to the association of
small cells, large clear spaces, and a certain amount of dark-coloured
material suggestive of tissue disorganisation and secreted products. The
anatomical characters of the secretory zone are shown in the photograph,
fig. 168, A, sc. Several leaf-traces are seen in transverse section in the
secretory zone (black dots in fig. 148, A, sc; fig. 154, C, lt): each trace
consists of a strand of narrow tracheae accompanied by a few encircling
layers of small parenchymatous cells. As a trace continues its steeply
ascending course through the secretory zone, it becomes associated with a
strand of that tissue and assumes the form of a collateral vascular bundle,
the outer part of which does not consist of typical phloem but of shorter
elements derived from the secretory zone. Beyond the secretory zone we
find a more homogeneous tissue composed of parenchymatous elements
slightly extended tangentially (figs. 148, A, c1; fig. 168, A, c); this is spoken
of as the inner cortical region. In the great majority of sections of L.
vasculare as of other species of the genus, the broader middle cortex (fig.
148, c2) is occupied by mineral matter, introduced subsequent to decay of
the tissue; or it is represented by patches of delicate tissue composed of
Page 147
loosely arranged parenchymatous cells varying considerably in size and
shape, some being small, oval or polygonal elements while others have the
form of sinuous hypha-like tubes.
In this middle cortical region may be seen leaf-traces passing outwards in
an almost horizontal course (fig. 148, A, lt): after leaving the inner cortex
the leaf-traces bend somewhat abruptly outwards to follow a more direct
path through the middle and outer cortex. The ring of tissue, s, seen in the
middle cortex of fig. 148, A, belongs to a Stigmarian rootlet.
The outer cortex (fig. 148, A and B, c3) consists of homogeneous
parenchyma which is stronger and more resistant to decay than the looser
middle cortex. The leaf-traces, as shown in fig. 148, B, pass through this
region in a rather steeply ascending direction: each is seen to be enclosed by
a space originally occupied by a strand of middle cortical tissue which
accompanies lepidodendroid leaf-traces on their under side and has already
been described as the parichnos, (pp. 97, 100–103; figs. 146, 147).
The surface of the stem shown in section in fig. 148, A, is composed of
broad leaf-cushions. A single leaf-trace with its parichnos passes into each
cushion, but in the neighbourhood of the base of a cushion the parichnos
bifurcates (cf. fig. 146, H, I) and the arms diverge slightly to the right and
left finally passing beyond the cushion into the lamina of the leaf, their
position being shown, as already explained, by the two small lateral scars
on the leaf-scar area.
The diagrammatic sketch of a radial longitudinal section through a leaf-
cushion represented in fig. 150 illustrates the relation of the leaf-trace to the
leaf-cushion. The trace consists of xylem, x, above and a strand of the
secretory zone, st, below; the parichnos tissue was originally present on the
under side of the leaf-trace at a. The external surface, bc, marks the limit of
the leaf-scar through the middle of which passes the vascular strand lt.
The lower gap a has been formed by the tearing of thin-walled cells of
the phellogen, the meristematic tissue from which a considerable amount of
secondary cortical tissue or phelloderm has been produced at pd. On the
outside of the cushion, c, the cells are somewhat crushed and distinguished
by their darker colour from the bulk of the parenchymatous tissue d.
shape, some being small, oval or polygonal elements while others have the
form of sinuous hypha-like tubes.
In this middle cortical region may be seen leaf-traces passing outwards in
an almost horizontal course (fig. 148, A, lt): after leaving the inner cortex
the leaf-traces bend somewhat abruptly outwards to follow a more direct
path through the middle and outer cortex. The ring of tissue, s, seen in the
middle cortex of fig. 148, A, belongs to a Stigmarian rootlet.
The outer cortex (fig. 148, A and B, c3) consists of homogeneous
parenchyma which is stronger and more resistant to decay than the looser
middle cortex. The leaf-traces, as shown in fig. 148, B, pass through this
region in a rather steeply ascending direction: each is seen to be enclosed by
a space originally occupied by a strand of middle cortical tissue which
accompanies lepidodendroid leaf-traces on their under side and has already
been described as the parichnos, (pp. 97, 100–103; figs. 146, 147).
The surface of the stem shown in section in fig. 148, A, is composed of
broad leaf-cushions. A single leaf-trace with its parichnos passes into each
cushion, but in the neighbourhood of the base of a cushion the parichnos
bifurcates (cf. fig. 146, H, I) and the arms diverge slightly to the right and
left finally passing beyond the cushion into the lamina of the leaf, their
position being shown, as already explained, by the two small lateral scars
on the leaf-scar area.
The diagrammatic sketch of a radial longitudinal section through a leaf-
cushion represented in fig. 150 illustrates the relation of the leaf-trace to the
leaf-cushion. The trace consists of xylem, x, above and a strand of the
secretory zone, st, below; the parichnos tissue was originally present on the
under side of the leaf-trace at a. The external surface, bc, marks the limit of
the leaf-scar through the middle of which passes the vascular strand lt.
The lower gap a has been formed by the tearing of thin-walled cells of
the phellogen, the meristematic tissue from which a considerable amount of
secondary cortical tissue or phelloderm has been produced at pd. On the
outside of the cushion, c, the cells are somewhat crushed and distinguished
by their darker colour from the bulk of the parenchymatous tissue d.
Page 148
This section also illustrates another characteristic feature of
Lepidodendron, namely the presence of a ligule and a ligular pit: the former
is represented by a carbonised patch of tissue and the latter extends from the
surface of the cushion at b, just above the leaf-scar, almost to the level of
the leaf-trace, lt. A comparison of this section with figs. 146 and 147 will
make clear the relation of the several parts of the cushion and leaf-scar.
The gaps gg, seen in fig. 148, A and B, mark the position of the delicate
meristematic zone or phellogen which arises close to the bases of the leaf-
cushions; the phellogen has already produced a few rows of radially
disposed elements, represented by short radial lines in the drawing, which
constitute secondary cortical tissue.
Fig. 150. Lepidodendron vasculare. Leaf-cushions in longitudinal section. (From a specimen
in Dr Kidston’s Collection.)
In older shoots the amount of the secondary cortical tissue developed on
the inner side of the phellogen is considerable (cf. figs. 152, 153).
Lepidodendron, namely the presence of a ligule and a ligular pit: the former
is represented by a carbonised patch of tissue and the latter extends from the
surface of the cushion at b, just above the leaf-scar, almost to the level of
the leaf-trace, lt. A comparison of this section with figs. 146 and 147 will
make clear the relation of the several parts of the cushion and leaf-scar.
The gaps gg, seen in fig. 148, A and B, mark the position of the delicate
meristematic zone or phellogen which arises close to the bases of the leaf-
cushions; the phellogen has already produced a few rows of radially
disposed elements, represented by short radial lines in the drawing, which
constitute secondary cortical tissue.
Fig. 150. Lepidodendron vasculare. Leaf-cushions in longitudinal section. (From a specimen
in Dr Kidston’s Collection.)
In older shoots the amount of the secondary cortical tissue developed on
the inner side of the phellogen is considerable (cf. figs. 152, 153).
Page 149
The structure of the cortex of a shoot in which secondary growth, both in
the stele and in the outer cortex, has progressed further than in the specimen
shown in fig. 148 is represented in fig. 151.
Fig. 151. Lepidodendron vasculare. An older stem than that shown in fig. 148. (From a
section in the Manchester Museum. No. 351.)
The section (fig. 151, A) measures 7 × 3·8 cm. in diameter; the primary
xylem is surrounded by a fairly broad cylinder of secondary wood (fig. 151,
E, x and x2). The almost smooth surface of the primary wood (fig. 151, E, x)
is succeeded by the secondary xylem, x2, characterised at its inner edge by
the tapered ends of the radial rows of scalariform tracheids between which
occur several delicate parenchymatous cells (fig. 151, E, a). The occurrence
of such isodiametric elements, often exhibiting a delicate spiral thickening
band, is a characteristic feature of the boundary between primary and
secondary wood in lepidodendroid stems. The secondary wood is penetrated
by numerous medullary rays and in some of them are seen strands of
narrow spirally thickened tracheae—the leaf-traces—which are in organic
continuity with the exarch protoxylem of the primary wood. The leaf-traces
are oval and mesarch. The space, c2, (fig. 151, A) originally occupied by the
delicate middle cortex, is succeeded by a shell of outer cortex composed
chiefly of secondary tissue (phelloderm, pd) passing towards the inner
the stele and in the outer cortex, has progressed further than in the specimen
shown in fig. 148 is represented in fig. 151.
Fig. 151. Lepidodendron vasculare. An older stem than that shown in fig. 148. (From a
section in the Manchester Museum. No. 351.)
The section (fig. 151, A) measures 7 × 3·8 cm. in diameter; the primary
xylem is surrounded by a fairly broad cylinder of secondary wood (fig. 151,
E, x and x2). The almost smooth surface of the primary wood (fig. 151, E, x)
is succeeded by the secondary xylem, x2, characterised at its inner edge by
the tapered ends of the radial rows of scalariform tracheids between which
occur several delicate parenchymatous cells (fig. 151, E, a). The occurrence
of such isodiametric elements, often exhibiting a delicate spiral thickening
band, is a characteristic feature of the boundary between primary and
secondary wood in lepidodendroid stems. The secondary wood is penetrated
by numerous medullary rays and in some of them are seen strands of
narrow spirally thickened tracheae—the leaf-traces—which are in organic
continuity with the exarch protoxylem of the primary wood. The leaf-traces
are oval and mesarch. The space, c2, (fig. 151, A) originally occupied by the
delicate middle cortex, is succeeded by a shell of outer cortex composed
chiefly of secondary tissue (phelloderm, pd) passing towards the inner
Page 150
boundary of this region into the primary outer cortex g (fig. 151, A and C).
The radially disposed elements which make up the bulk of the phelloderm
are associated with concentric rows of secretory strands, represented by
tangentially arranged dots in fig. 151, A: on the outer edge of the
phelloderm a few patches of primary cortex are still preserved, as at c, fig.
A. One of these is shown on a larger scale in fig. B; at m the phelloderm is
interrupted by a gap beyond which the cells have thinner walls and show
signs of recent division; this is probably the position of the phellogen. The
tissue b, fig. 151, B, consists of secondary cortex succeeded beyond d by
the parenchymatous tissue of the leaf-cushion, in which the remains of a
ligule, l, are seen in the ligular pit. This section corresponds in position to a
line drawn across fig. 150 at the level of b. In this specimen we have two
kinds of secondary cortical tissue: that formed external to the phellogen,
from m to d in fig. 151, B, is less in amount than that produced internal to
the phellogen. We cannot make any satisfactory statement as to the nature
of this secondary tissue, whether or not any of it agreed in composition with
the cork which is usually formed external to the phellogen in recent plants.
As the stem of a Lepidodendron grew in girth the leaf-cushions became
separated by intervening depressions composed of the secondary cortex
formed external to the phellogen, but at a later stage the cushions were
thrown off, leaving the outer edge of the phelloderm as the superficial
tissue. This exposed tissue became fissured as growth and consequent
stretching continued, producing the appearance seen on the surface of the
still older stem represented in fig. 153.
The inner edge of the phelloderm seen at e in fig. 151, C, passes suddenly
into the inner primary region of the outer cortex (fig. 151, A and C, g)
which comprises two types of parenchymatous tissue, patches of
isodiametric cells, g, g, alternating with radially arranged areas consisting
of tangentially elongated elements (fig. C, f, f; fig. D) which extend as
wedges into the phelloderm.
The longitudinal section represented in fig. 152, B, shows an equal
bifurcation of a stem in which no secondary xylem is present; in the lower
part of the section the xylem and the outgoing leaf-traces are seen in radial
section and at the upper end of each arm the leaf-traces alone, lt, are
exposed, as in fig. 148, B. It is interesting to notice the large amount of
The radially disposed elements which make up the bulk of the phelloderm
are associated with concentric rows of secretory strands, represented by
tangentially arranged dots in fig. 151, A: on the outer edge of the
phelloderm a few patches of primary cortex are still preserved, as at c, fig.
A. One of these is shown on a larger scale in fig. B; at m the phelloderm is
interrupted by a gap beyond which the cells have thinner walls and show
signs of recent division; this is probably the position of the phellogen. The
tissue b, fig. 151, B, consists of secondary cortex succeeded beyond d by
the parenchymatous tissue of the leaf-cushion, in which the remains of a
ligule, l, are seen in the ligular pit. This section corresponds in position to a
line drawn across fig. 150 at the level of b. In this specimen we have two
kinds of secondary cortical tissue: that formed external to the phellogen,
from m to d in fig. 151, B, is less in amount than that produced internal to
the phellogen. We cannot make any satisfactory statement as to the nature
of this secondary tissue, whether or not any of it agreed in composition with
the cork which is usually formed external to the phellogen in recent plants.
As the stem of a Lepidodendron grew in girth the leaf-cushions became
separated by intervening depressions composed of the secondary cortex
formed external to the phellogen, but at a later stage the cushions were
thrown off, leaving the outer edge of the phelloderm as the superficial
tissue. This exposed tissue became fissured as growth and consequent
stretching continued, producing the appearance seen on the surface of the
still older stem represented in fig. 153.
The inner edge of the phelloderm seen at e in fig. 151, C, passes suddenly
into the inner primary region of the outer cortex (fig. 151, A and C, g)
which comprises two types of parenchymatous tissue, patches of
isodiametric cells, g, g, alternating with radially arranged areas consisting
of tangentially elongated elements (fig. C, f, f; fig. D) which extend as
wedges into the phelloderm.
The longitudinal section represented in fig. 152, B, shows an equal
bifurcation of a stem in which no secondary xylem is present; in the lower
part of the section the xylem and the outgoing leaf-traces are seen in radial
section and at the upper end of each arm the leaf-traces alone, lt, are
exposed, as in fig. 148, B. It is interesting to notice the large amount of
Page 151
phelloderm which has been produced in the fork of the branch, at pd, where
greater strength is required.
Fig. 152. Lepidodendron vasculare. Sections of dichotomously branched shoot.
A. From a section (10·5 × 9 cm.) in the Cambridge Botany School Collection.
B. From a section (8 cm. long) in the Cambridge Collection.
The section represented diagrammatically in fig. 152, A, has lost the
outermost part of the cortex together with the leaf-cushions; it consists
largely of secondary cortex composed of radially disposed phelloderm cells
and tangentially placed secretory strands (represented by the discontinuous
greater strength is required.
Fig. 152. Lepidodendron vasculare. Sections of dichotomously branched shoot.
A. From a section (10·5 × 9 cm.) in the Cambridge Botany School Collection.
B. From a section (8 cm. long) in the Cambridge Collection.
The section represented diagrammatically in fig. 152, A, has lost the
outermost part of the cortex together with the leaf-cushions; it consists
largely of secondary cortex composed of radially disposed phelloderm cells
and tangentially placed secretory strands (represented by the discontinuous
Page 152
black lines in the drawing): the dotted region in the central part of the axis
is composed of primary cortical parenchyma, and the two spaces
surrounding the steles contain portions of the lacunar middle cortex. Each
stele possesses a narrow crescentic zone of secondary xylem; the amount is
greater in the case of the right-hand stele, of which a small piece is shown
on a larger scale; the striking contrast in size between the outer and more
internal secondary tracheae is no doubt the expression of some
unfavourable condition of growth. The position of the secretory zone
beyond the secondary xylem is shown at sc, fig. 152, A.
Fig. 153. Lepidodendron vasculare.
(From a specimen (16 × 7·5 cm.) in the Manchester Museum.)
An example of a large and partially decorticated stem is afforded by the
specimen (16 × 7·5 cm.) shown in fig. 153. The irregularly ribbed surface is
formed of rather thick-walled phelloderm, in which occur tangentially
is composed of primary cortical parenchyma, and the two spaces
surrounding the steles contain portions of the lacunar middle cortex. Each
stele possesses a narrow crescentic zone of secondary xylem; the amount is
greater in the case of the right-hand stele, of which a small piece is shown
on a larger scale; the striking contrast in size between the outer and more
internal secondary tracheae is no doubt the expression of some
unfavourable condition of growth. The position of the secretory zone
beyond the secondary xylem is shown at sc, fig. 152, A.
Fig. 153. Lepidodendron vasculare.
(From a specimen (16 × 7·5 cm.) in the Manchester Museum.)
An example of a large and partially decorticated stem is afforded by the
specimen (16 × 7·5 cm.) shown in fig. 153. The irregularly ribbed surface is
formed of rather thick-walled phelloderm, in which occur tangentially
Page 153
arranged rows of secretory strands. The tapered form of the secondary
cortex as it abuts internally on the primary cortex is shown very clearly in
the drawing (cf. fig. 151, C). The stele in this much older stem consists
mainly of secondary wood.
Fig. 154. Lepidodendron vasculare. Shoot (2·8 cm. diam.) with two steles. (From a specimen
from Halifax in the Williamson Collection, British Museum, No. 340.)
An interesting example of a small shoot, the largest diameter of which is
2·8 cm., is shown in fig. 154, A: the section was cut a short distance above
the bifurcation of the stele into two approximately equal branches. The
outer part of the cortex consists of phelloderm, pd, with the usual rows of
secretory tracts, and primary outer cortex g; the middle cortex is
represented by patches of parenchyma with a few leaf-traces. To one of the
steles, s′ (fig. 154, A), a crescent-shaped band of secondary xylem has been
added; the other stele, S, possesses no fully developed secondary elements.
Fig. 154, B and C, illustrates the anatomical features immediately
external to the primary xylem of the smaller stele, s. The comparatively
cortex as it abuts internally on the primary cortex is shown very clearly in
the drawing (cf. fig. 151, C). The stele in this much older stem consists
mainly of secondary wood.
Fig. 154. Lepidodendron vasculare. Shoot (2·8 cm. diam.) with two steles. (From a specimen
from Halifax in the Williamson Collection, British Museum, No. 340.)
An interesting example of a small shoot, the largest diameter of which is
2·8 cm., is shown in fig. 154, A: the section was cut a short distance above
the bifurcation of the stele into two approximately equal branches. The
outer part of the cortex consists of phelloderm, pd, with the usual rows of
secretory tracts, and primary outer cortex g; the middle cortex is
represented by patches of parenchyma with a few leaf-traces. To one of the
steles, s′ (fig. 154, A), a crescent-shaped band of secondary xylem has been
added; the other stele, S, possesses no fully developed secondary elements.
Fig. 154, B and C, illustrates the anatomical features immediately
external to the primary xylem of the smaller stele, s. The comparatively
Page 154
broad band of radially disposed parenchyma, m, is connected with the
outermost elements of the xylem by a few rather dark and small crushed
parenchymatous cells. The band m, which we may speak of as the
meristematic zone, clearly consists of cells in a state of division; it is in this
region that the secondary xylem is produced. Beyond the leaf-trace, (fig.
154, C, lt), occurs a portion of the secretory zone, some of the smaller cells
of which show signs of disorganisation; but most of this tissue has been
destroyed (fig. 154, B, sc). The outer edge of the secretory zone is shown in
fig. 154, D abutting on the cells of the inner cortex, c′. The leaf-trace shown
in the inner cortex in fig. 154, B illustrates the more oval or tangentially
extended form of the xylem in this region, in contrast to the more circular
outline which it exhibits on the inner side of the secretory zone.
Fig. 155. Lepidodendron vasculare. Outer edge of secondary xylem: m, meristematic zone;
mr, medullary ray. (Drawn from the section shown in fig. 168, A).
The transverse section, part of which is reproduced in fig. 168, A,
illustrates a characteristic feature, namely the juxtaposition of the outermost
tracheae of the secondary xylem and much smaller cells of the meristematic
zone. This is seen in fig. 155, which shows a small piece of fig. 168, A, on a
larger scale. In plants with a normal cambium the segments cut off from the
initial layer fit on to the elements of the xylem or phloem to which they are
to form additions, but in Lepidodendron it seems to be a general rule to find
each of the most external lignified elements abutting on a group of two or
outermost elements of the xylem by a few rather dark and small crushed
parenchymatous cells. The band m, which we may speak of as the
meristematic zone, clearly consists of cells in a state of division; it is in this
region that the secondary xylem is produced. Beyond the leaf-trace, (fig.
154, C, lt), occurs a portion of the secretory zone, some of the smaller cells
of which show signs of disorganisation; but most of this tissue has been
destroyed (fig. 154, B, sc). The outer edge of the secretory zone is shown in
fig. 154, D abutting on the cells of the inner cortex, c′. The leaf-trace shown
in the inner cortex in fig. 154, B illustrates the more oval or tangentially
extended form of the xylem in this region, in contrast to the more circular
outline which it exhibits on the inner side of the secretory zone.
Fig. 155. Lepidodendron vasculare. Outer edge of secondary xylem: m, meristematic zone;
mr, medullary ray. (Drawn from the section shown in fig. 168, A).
The transverse section, part of which is reproduced in fig. 168, A,
illustrates a characteristic feature, namely the juxtaposition of the outermost
tracheae of the secondary xylem and much smaller cells of the meristematic
zone. This is seen in fig. 155, which shows a small piece of fig. 168, A, on a
larger scale. In plants with a normal cambium the segments cut off from the
initial layer fit on to the elements of the xylem or phloem to which they are
to form additions, but in Lepidodendron it seems to be a general rule to find
each of the most external lignified elements abutting on a group of two or
Page 155
three much smaller cells. It is difficult to believe that the meristem shown in
fig. 155, m, could produce secondary xylem elements equal in size to those
already formed: in all probability had growth continued there would have
been a marked difference between the size of the secondary tracheids, as in
fig. 152, A, x2, where there was no doubt some cause which interfered with
normal cambial activity. This disparity in size between the secondary xylem
elements and the adjacent parenchymatous tissue of the meristematic zone
is by no means exceptional and may be described as the general rule. It is at
least certain that in Lepidodendron vasculare, as in other species, the
secondary xylem was succeeded by a broad band of parenchymatous tissue,
from which new tracheae and medullary-ray elements were produced, and
not by a narrow cambium such as occurs in recent plants.
v. Lepidodendron stems as represented by casts and impressions
of partially decorticated specimens.
The differentiation of the outer cortex of a Lepidodendron into
comparatively thin-walled and more resistant tissue has been the cause of
unequal decay and the consequent formation of shrinkage cavities. In
addition to the unequal resisting power of contiguous tissues, another
important factor in determining the nature of casts and impressions is the
existence of the cylinder of delicate cells in the outer cortex of stems and
branches. As already pointed out, this meristematic cylinder or phellogen
constitutes a natural line of separation, as in the case of the cambium layer
between the wood and the external tissues in a fresh Sycamore twig. The
result of the separation of an outer shell of bark from the rest of the stem
and the results of unequal decay in the more superficial tissues, have
necessarily led to the preservation of the same specific type under a variety
of forms.
Our knowledge of the anatomy of Lepidodendron stems enables us to
recognise in fossils of very different appearance specimens in various
conditions of preservation of one and the same type. Such names as
Knorria, Bergeria and Aspidiaria are examples of generic titles instituted
before any adequate knowledge of Lepidodendron anatomy was available.
Differences in age as well as different degrees of decortication have
contributed in no small measure to the institution of generic and specific
fig. 155, m, could produce secondary xylem elements equal in size to those
already formed: in all probability had growth continued there would have
been a marked difference between the size of the secondary tracheids, as in
fig. 152, A, x2, where there was no doubt some cause which interfered with
normal cambial activity. This disparity in size between the secondary xylem
elements and the adjacent parenchymatous tissue of the meristematic zone
is by no means exceptional and may be described as the general rule. It is at
least certain that in Lepidodendron vasculare, as in other species, the
secondary xylem was succeeded by a broad band of parenchymatous tissue,
from which new tracheae and medullary-ray elements were produced, and
not by a narrow cambium such as occurs in recent plants.
v. Lepidodendron stems as represented by casts and impressions
of partially decorticated specimens.
The differentiation of the outer cortex of a Lepidodendron into
comparatively thin-walled and more resistant tissue has been the cause of
unequal decay and the consequent formation of shrinkage cavities. In
addition to the unequal resisting power of contiguous tissues, another
important factor in determining the nature of casts and impressions is the
existence of the cylinder of delicate cells in the outer cortex of stems and
branches. As already pointed out, this meristematic cylinder or phellogen
constitutes a natural line of separation, as in the case of the cambium layer
between the wood and the external tissues in a fresh Sycamore twig. The
result of the separation of an outer shell of bark from the rest of the stem
and the results of unequal decay in the more superficial tissues, have
necessarily led to the preservation of the same specific type under a variety
of forms.
Our knowledge of the anatomy of Lepidodendron stems enables us to
recognise in fossils of very different appearance specimens in various
conditions of preservation of one and the same type. Such names as
Knorria, Bergeria and Aspidiaria are examples of generic titles instituted
before any adequate knowledge of Lepidodendron anatomy was available.
Differences in age as well as different degrees of decortication have
contributed in no small measure to the institution of generic and specific
Page 156
names which more recently acquired knowledge has shown to be
superfluous.
a. Knorria.
The designation Knorria, after a certain G. W. Knorr of Nürnberg, was
proposed by Sternberg in 1826[273] for casts of Palaeozoic stems of a type
figured more than a century earlier by Volkmann[274]. Goeppert, in his earlier
works, published drawings of fossil stems which he referred to Sternberg’s
genus: one species he at first called Didymophyllum Schollini. He
afterwards[275] described some specimens which showed that the features
characteristic of Knorria may occur on partially decorticated stems with
leaf-cushions of the true Lepidodendron type. His specimens, preserved in
the Breslau Museum, demonstrate the accuracy of his drawings and
conclusions. Goeppert, and after him Balfour[276], drew attention to the
different appearances presented by branches of Araucaria imbricata when
preserved with the surface intact and after partial decortication, as
illustrating possible sources of error in the determination of fossil stems.
Although it is now a well-established fact that fossils bearing the name
Knorria are imperfect lepidodendroid stems, the use of the term may be
conveniently retained for descriptive purposes. The specimen from the
Commentry coal-field of France, shown in fig. 156, affords some excuse for
the institution of several generic names for different states of preservation
or decortication of one species. The cortical level exposed at e is
characterised by spirally disposed peg-like ridges with truncated apices: it is
this form of cast which is usually designated Knorria. The ridges vary in
size and shape in different types of stem; they may be narrow as shown at e,
fig. 156, or short and broad with rounded distal ends. In some cases they are
forked at the apex, as in the partially decorticated specimen of
Lepidodendron Veltheimianum represented in fig. 185, A.
superfluous.
a. Knorria.
The designation Knorria, after a certain G. W. Knorr of Nürnberg, was
proposed by Sternberg in 1826[273] for casts of Palaeozoic stems of a type
figured more than a century earlier by Volkmann[274]. Goeppert, in his earlier
works, published drawings of fossil stems which he referred to Sternberg’s
genus: one species he at first called Didymophyllum Schollini. He
afterwards[275] described some specimens which showed that the features
characteristic of Knorria may occur on partially decorticated stems with
leaf-cushions of the true Lepidodendron type. His specimens, preserved in
the Breslau Museum, demonstrate the accuracy of his drawings and
conclusions. Goeppert, and after him Balfour[276], drew attention to the
different appearances presented by branches of Araucaria imbricata when
preserved with the surface intact and after partial decortication, as
illustrating possible sources of error in the determination of fossil stems.
Although it is now a well-established fact that fossils bearing the name
Knorria are imperfect lepidodendroid stems, the use of the term may be
conveniently retained for descriptive purposes. The specimen from the
Commentry coal-field of France, shown in fig. 156, affords some excuse for
the institution of several generic names for different states of preservation
or decortication of one species. The cortical level exposed at e is
characterised by spirally disposed peg-like ridges with truncated apices: it is
this form of cast which is usually designated Knorria. The ridges vary in
size and shape in different types of stem; they may be narrow as shown at e,
fig. 156, or short and broad with rounded distal ends. In some cases they are
forked at the apex, as in the partially decorticated specimen of
Lepidodendron Veltheimianum represented in fig. 185, A.
Page 157
Fig. 156. A dichotomously branched Lepidodendroid stem (Knorria mirabilis Ren. and
Zeill.). (After Renault and Zeiller.) (¼ nat. size.) The original specimen is in the
Natural History Museum, Paris.
a–g, surface features exposed as the result of different degrees of decortication.
(See vol. i. p. 102, fig. 23).
The Knorria state represents the impression or cast of the outer cortical
region too deep below the leaf-cushion region to retain any indications of
the cushion-form; the ridges are the casts of the spaces produced in the
cortex by the decay of the sheath of delicate cells surrounding each leaf-
trace and by the decay of the thin-walled cells of the parichnos. The
occasional forked apex of a ridge is the expression of the fact that the cast
was made at the region where the parichnos divides into two arms (cf. p.
100). In certain specimens it is possible to connect the Knorria casts with
associated lepidodendroid stems which may be determined specifically; but
Zeill.). (After Renault and Zeiller.) (¼ nat. size.) The original specimen is in the
Natural History Museum, Paris.
a–g, surface features exposed as the result of different degrees of decortication.
(See vol. i. p. 102, fig. 23).
The Knorria state represents the impression or cast of the outer cortical
region too deep below the leaf-cushion region to retain any indications of
the cushion-form; the ridges are the casts of the spaces produced in the
cortex by the decay of the sheath of delicate cells surrounding each leaf-
trace and by the decay of the thin-walled cells of the parichnos. The
occasional forked apex of a ridge is the expression of the fact that the cast
was made at the region where the parichnos divides into two arms (cf. p.
100). In certain specimens it is possible to connect the Knorria casts with
associated lepidodendroid stems which may be determined specifically; but
Page 158
when we have no evidence as to surface-features the fossils may be
designated casts of lepidodendroid stems in the Knorria condition. Such
casts are illustrated by numerous drawings in palaeobotanical literature[277].
b. Bergeria.
This is another name first used by Sternberg in his classic work, Die
Flora der Vorwelt, for casts of lepidodendroid plants such as Steinhauer[278]
had previously figured as Phytolithus cancellatus. Brongniart[279] recognised
that the application of the generic title Lepidodendron should be extended
to include specimens referred by Sternberg to Bergeria, and a few years
later Goldenberg[280] realised that this name does not stand for well-defined
generic characters. The correctness of these views was, however, first
satisfactorily demonstrated by Carruthers[281] and by Feistmantel[282].
If a Lepidodendron stem loses its superficial layers of outer cortex and in
this condition is embedded in sand or mud, the cast is distinguished from
that of a perfect stem by the absence of the leaf-scars and by other features.
It may, however, still show spirally disposed areas, corresponding
approximately to the original leaf-cushions, which are characterised by a
small depression or pit either at the apex or near the centre of each oval
area: the pit marks the position of the leaf-trace and its parichnos strand. In
some cases the exposed surface may be smooth without any indication of
leaf-cushions, while narrow spirally arranged grooves represent the
obliquely ascending vascular bundles passing through the cortex to the
leaves.
Fig. 185, B, shows the Bergeria state of Lepidodendron Veltheimianum,
which differs from the Knorria condition in the fact that decortication had
not extended below the level at which the form of the leaf-cushions could
be recognised. It is clear that no sharp line can be drawn in all cases
between the different degrees of decortication as expressed by the terms
Knorria and Bergeria.
A list of synonyms of Knorria, Bergeria, and Aspidiaria forms of stem
and a detailed treatment of their characteristic features may be found in a
recent work by Potonié[283].
c. Aspidiaria.
designated casts of lepidodendroid stems in the Knorria condition. Such
casts are illustrated by numerous drawings in palaeobotanical literature[277].
b. Bergeria.
This is another name first used by Sternberg in his classic work, Die
Flora der Vorwelt, for casts of lepidodendroid plants such as Steinhauer[278]
had previously figured as Phytolithus cancellatus. Brongniart[279] recognised
that the application of the generic title Lepidodendron should be extended
to include specimens referred by Sternberg to Bergeria, and a few years
later Goldenberg[280] realised that this name does not stand for well-defined
generic characters. The correctness of these views was, however, first
satisfactorily demonstrated by Carruthers[281] and by Feistmantel[282].
If a Lepidodendron stem loses its superficial layers of outer cortex and in
this condition is embedded in sand or mud, the cast is distinguished from
that of a perfect stem by the absence of the leaf-scars and by other features.
It may, however, still show spirally disposed areas, corresponding
approximately to the original leaf-cushions, which are characterised by a
small depression or pit either at the apex or near the centre of each oval
area: the pit marks the position of the leaf-trace and its parichnos strand. In
some cases the exposed surface may be smooth without any indication of
leaf-cushions, while narrow spirally arranged grooves represent the
obliquely ascending vascular bundles passing through the cortex to the
leaves.
Fig. 185, B, shows the Bergeria state of Lepidodendron Veltheimianum,
which differs from the Knorria condition in the fact that decortication had
not extended below the level at which the form of the leaf-cushions could
be recognised. It is clear that no sharp line can be drawn in all cases
between the different degrees of decortication as expressed by the terms
Knorria and Bergeria.
A list of synonyms of Knorria, Bergeria, and Aspidiaria forms of stem
and a detailed treatment of their characteristic features may be found in a
recent work by Potonié[283].
c. Aspidiaria.
Page 159
In one of the earliest English books on fossil plants, the Antediluvian
Phytology by Artis[284], a specimen from the Carboniferous sandstone of
Yorkshire is figured as Aphyllum cristatum, and a similar fossil is described
as A. asperum. These are impressions of Lepidodendron stems in which the
characteristic leaf-cushions are replaced by smooth and slightly convex
areas with a narrow central ridge. To this type of specimen Presl gave the
name Aspidiaria[285], under the impression, shared by subsequent writers,
that the supposed external features were entitled to generic recognition.
It is to Stur[286] that we owe the first satisfactory interpretation of fossils
included under the name Aspidiaria: he showed that on the removal of the
projecting convex areas from some of his specimens a typical
Lepidodendron leaf-cushion was exposed (fig. 144, A, a). The Aspidiaria
condition (fig. 144, A, b) represents the inner face of the detached shell of
outer bark of a Lepidodendron stem, while in the Bergeria casts we have a
view of the external face of a stem deprived of its superficial tissues.
In a Lepidodendron stem embedded in sediment the more delicate
portions of the leaf-cushions would tend to shrink away from the internal
and more resistant tissues of the outer cortex, thus producing spaces
between each cushion; further decay would cause rupture of the leaf-traces
and the superficial tissues would thus be separated from the rest of the stem.
The tendency of Lepidodendron stems to split along the line of phellogen in
the outer cortex is seen in fig. 148, A, g. The deposition of sediment on the
exposed inner face of this cortical shell would result in the production of a
specimen of the Aspidiaria type: the reticulum enclosing the spirally
disposed convex areas is formed by the impression of the firmer tissue
between the leaf-cushions.
vi. Lepidodendroid axes known as Ulodendron and Halonia.
a. Ulodendron.
This generic name was suggested by Lindley and Hutton[287] for two
specimens from the English Coal-measures characterised by leaf-cushions
like those of a Lepidodendron, but distinguished by the presence of two
vertical rows of large and more or less circular cup-shaped scars. These
authors, while recognising the possibility that the fossils might be identical
Phytology by Artis[284], a specimen from the Carboniferous sandstone of
Yorkshire is figured as Aphyllum cristatum, and a similar fossil is described
as A. asperum. These are impressions of Lepidodendron stems in which the
characteristic leaf-cushions are replaced by smooth and slightly convex
areas with a narrow central ridge. To this type of specimen Presl gave the
name Aspidiaria[285], under the impression, shared by subsequent writers,
that the supposed external features were entitled to generic recognition.
It is to Stur[286] that we owe the first satisfactory interpretation of fossils
included under the name Aspidiaria: he showed that on the removal of the
projecting convex areas from some of his specimens a typical
Lepidodendron leaf-cushion was exposed (fig. 144, A, a). The Aspidiaria
condition (fig. 144, A, b) represents the inner face of the detached shell of
outer bark of a Lepidodendron stem, while in the Bergeria casts we have a
view of the external face of a stem deprived of its superficial tissues.
In a Lepidodendron stem embedded in sediment the more delicate
portions of the leaf-cushions would tend to shrink away from the internal
and more resistant tissues of the outer cortex, thus producing spaces
between each cushion; further decay would cause rupture of the leaf-traces
and the superficial tissues would thus be separated from the rest of the stem.
The tendency of Lepidodendron stems to split along the line of phellogen in
the outer cortex is seen in fig. 148, A, g. The deposition of sediment on the
exposed inner face of this cortical shell would result in the production of a
specimen of the Aspidiaria type: the reticulum enclosing the spirally
disposed convex areas is formed by the impression of the firmer tissue
between the leaf-cushions.
vi. Lepidodendroid axes known as Ulodendron and Halonia.
a. Ulodendron.
This generic name was suggested by Lindley and Hutton[287] for two
specimens from the English Coal-measures characterised by leaf-cushions
like those of a Lepidodendron, but distinguished by the presence of two
vertical rows of large and more or less circular cup-shaped scars. These
authors, while recognising the possibility that the fossils might be identical
Page 160
with Lepidodendron, regarded them as generically distinct. The generic title
Ulodendron, though no longer denoting generic rank, is still applied to
certain shoots of lycopodiaceous plants which may belong to the genera
Lepidodendron, Bothrodendron, and according to some authors[288], also to
Sigillaria.
The large specimen from the Belgian coal-measures, represented in fig.
211, affords a good example of the Ulodendron form of shoot of the genus
Bothrodendron, which is described on page 249. The specimen shown in
fig. 157 shows the Ulodendron shoot of Lepidodendron Veltheimianum.
Casts of large Ulodendron scars are occasionally met with as separate
fossils bearing a resemblance to an oval shell.
In Steinhauer’s paper on Fossil Reliquiae[289] a drawing is given of a
Ulodendron stem under the name Phytolithus parmatus and a similar stem
specifically identical with that shown in fig. 157 was figured by Rhode[290],
one of the earliest writers on fossil plants, under the comprehensive
designation “Schuppenpflanze.”
Ulodendron, though no longer denoting generic rank, is still applied to
certain shoots of lycopodiaceous plants which may belong to the genera
Lepidodendron, Bothrodendron, and according to some authors[288], also to
Sigillaria.
The large specimen from the Belgian coal-measures, represented in fig.
211, affords a good example of the Ulodendron form of shoot of the genus
Bothrodendron, which is described on page 249. The specimen shown in
fig. 157 shows the Ulodendron shoot of Lepidodendron Veltheimianum.
Casts of large Ulodendron scars are occasionally met with as separate
fossils bearing a resemblance to an oval shell.
In Steinhauer’s paper on Fossil Reliquiae[289] a drawing is given of a
Ulodendron stem under the name Phytolithus parmatus and a similar stem
specifically identical with that shown in fig. 157 was figured by Rhode[290],
one of the earliest writers on fossil plants, under the comprehensive
designation “Schuppenpflanze.”
Page 161
Fig. 157. Lepidodendron Veltheimianum. Ulodendron condition. (From a photograph by Dr
Kidston of a specimen from the Calciferous Sandstone series, Midlothian; ⅖ nat.
size.) [Kidston (02) Pl. lvii.
There has been no lack of ingenuity on the part of authors in offering
suggestions as to the meaning of these large cup-like depressions, and there
is still difference of opinion as to their significance. Lindley and Hutton[291]
described them as the scars of branches or masses of inflorescence. Sir
Joseph Hooker[292] speaks of a specimen of Ulodendron, shown to him by
Mr Dawes, on which a large organ, supposed to be a cone, was inserted in
one of the depressions, but he was unable to arrive at any conclusion as to
the real nature of the fossil. While most authors have seen in the scars
Kidston of a specimen from the Calciferous Sandstone series, Midlothian; ⅖ nat.
size.) [Kidston (02) Pl. lvii.
There has been no lack of ingenuity on the part of authors in offering
suggestions as to the meaning of these large cup-like depressions, and there
is still difference of opinion as to their significance. Lindley and Hutton[291]
described them as the scars of branches or masses of inflorescence. Sir
Joseph Hooker[292] speaks of a specimen of Ulodendron, shown to him by
Mr Dawes, on which a large organ, supposed to be a cone, was inserted in
one of the depressions, but he was unable to arrive at any conclusion as to
the real nature of the fossil. While most authors have seen in the scars
Page 162
pressure-areas formed by the pressure of sessile cones against the surface of
a growing branch, others, as for example Geinitz[293], have described the
depressions as branch-scars. Carruthers[294] regarded the scars as those of
adventitious roots and Williamson referred to them as the scars of
reproductive shoots. The depressions vary considerably in size. The Belgian
example shown in fig. 211 possesses scars 9 cm. in diameter. A specimen of
Bothrodendron in the Manchester Museum from the Lancashire Coal-
Measures, to which Williamson[295] has referred, bears two rows of scars 11–
12 cm. in diameter on a stem 112 cm. in girth and 233 cm. long. The scars
occur in two alternate series, on opposite faces of the axis, the distance
between the successive scars in the same row being 29 cm. The surface-
features of this large stem are not preserved.
Before considering the nature and origin of the scars it is important to
remember the considerable size to which they may attain; other points of
importance are the occurrence, either in the centre of each depression or in
an excentric position, of an umbilicus or slightly projecting boss, in the
centre of which is a pit formed by the decay of an outgoing vascular strand.
The sloping sides of the scars sometimes bear elevations resembling leaf-
cushions like those on the rest of the stem surface. In the specimen shown
in fig. 157 the lower margin of each cup shows indistinctly the outlines of
what appear to be leaf-cushions, while the rest of the sloping face is
characterised by radial ridges, which may be due to bracts or leaves.
It is obvious that in these cups we have the scars of some lateral organ,
but the evidence afforded by specimens of which the depressions contain
the remains of such organs is by no means conclusive. A Ulodendron has
been figured by D’Arcy Thompson[296], in which the lower part of a lateral
organ is attached by a narrow base to one of the scars, but the preservation
is not sufficiently good to enable us to decide whether the organ is a cone or
a vegetative shoot. Kidston[297] has described other examples showing
portions of organs in connexion with the scars, but an examination of the
specimens in his collection failed to convince me that his interpretation of
them as strobili is correct.
The phenomenon known as cladoptosis, as shown on a stem of the
Conifer Agathis[298] and certain Dicotyledonous trees such as Castilloa,
suggests a possible explanation of the Ulodendron scars. This comparison
was made by Shattock[299] in 1888, but he did not accept the resemblance as
a growing branch, others, as for example Geinitz[293], have described the
depressions as branch-scars. Carruthers[294] regarded the scars as those of
adventitious roots and Williamson referred to them as the scars of
reproductive shoots. The depressions vary considerably in size. The Belgian
example shown in fig. 211 possesses scars 9 cm. in diameter. A specimen of
Bothrodendron in the Manchester Museum from the Lancashire Coal-
Measures, to which Williamson[295] has referred, bears two rows of scars 11–
12 cm. in diameter on a stem 112 cm. in girth and 233 cm. long. The scars
occur in two alternate series, on opposite faces of the axis, the distance
between the successive scars in the same row being 29 cm. The surface-
features of this large stem are not preserved.
Before considering the nature and origin of the scars it is important to
remember the considerable size to which they may attain; other points of
importance are the occurrence, either in the centre of each depression or in
an excentric position, of an umbilicus or slightly projecting boss, in the
centre of which is a pit formed by the decay of an outgoing vascular strand.
The sloping sides of the scars sometimes bear elevations resembling leaf-
cushions like those on the rest of the stem surface. In the specimen shown
in fig. 157 the lower margin of each cup shows indistinctly the outlines of
what appear to be leaf-cushions, while the rest of the sloping face is
characterised by radial ridges, which may be due to bracts or leaves.
It is obvious that in these cups we have the scars of some lateral organ,
but the evidence afforded by specimens of which the depressions contain
the remains of such organs is by no means conclusive. A Ulodendron has
been figured by D’Arcy Thompson[296], in which the lower part of a lateral
organ is attached by a narrow base to one of the scars, but the preservation
is not sufficiently good to enable us to decide whether the organ is a cone or
a vegetative shoot. Kidston[297] has described other examples showing
portions of organs in connexion with the scars, but an examination of the
specimens in his collection failed to convince me that his interpretation of
them as strobili is correct.
The phenomenon known as cladoptosis, as shown on a stem of the
Conifer Agathis[298] and certain Dicotyledonous trees such as Castilloa,
suggests a possible explanation of the Ulodendron scars. This comparison
was made by Shattock[299] in 1888, but he did not accept the resemblance as
Page 163
a real one. An objection may be urged to the cladoptosis hypothesis that in
Ulodendron the branch, whether vegetative or reproductive, was not
attached to the whole of the depressed area. On the other hand, a lateral
branch originally attached by a narrow base may have continued to increase
in diameter until its base became slightly sunk in the bark of the stem, thus
producing a cup-like depression which, on the fall of the branch, would
retain traces of the original surface-features of the stem.
Mr Watson[300] of Manchester recently published a paper on Ulodendron
scars, in which he adduces fresh and, as it seems to me, satisfactory
arguments in favour of the branch-scar hypothesis. Fig. 158, from one of
Mr Watson’s blocks, illustrates the nature of his evidence. He points out that
in the obverse half of a large specimen of Bothrodendron in the Manchester
Museum, the umbilicus consists of a cylindrical hole, 18 mm. deep and 8
mm. in diameter, surrounded by a projecting ring of mineral material which
doubtless represents some portion of the original plant: on the reverse half
of the specimen the continuation of the ring is seen as a prominent cone
fitting into the cup-like depression in the obverse half: the conical cast
shows that numerous small vascular strands were given off from this ring of
tissue, and these strands have the same arrangement and size as the dots
which are found on typical Ulodendron scars. He interprets the ring
surrounding the umbilicus as the remains of the primary wood and the small
strands as leaf-traces supplying the branch.
Ulodendron the branch, whether vegetative or reproductive, was not
attached to the whole of the depressed area. On the other hand, a lateral
branch originally attached by a narrow base may have continued to increase
in diameter until its base became slightly sunk in the bark of the stem, thus
producing a cup-like depression which, on the fall of the branch, would
retain traces of the original surface-features of the stem.
Mr Watson[300] of Manchester recently published a paper on Ulodendron
scars, in which he adduces fresh and, as it seems to me, satisfactory
arguments in favour of the branch-scar hypothesis. Fig. 158, from one of
Mr Watson’s blocks, illustrates the nature of his evidence. He points out that
in the obverse half of a large specimen of Bothrodendron in the Manchester
Museum, the umbilicus consists of a cylindrical hole, 18 mm. deep and 8
mm. in diameter, surrounded by a projecting ring of mineral material which
doubtless represents some portion of the original plant: on the reverse half
of the specimen the continuation of the ring is seen as a prominent cone
fitting into the cup-like depression in the obverse half: the conical cast
shows that numerous small vascular strands were given off from this ring of
tissue, and these strands have the same arrangement and size as the dots
which are found on typical Ulodendron scars. He interprets the ring
surrounding the umbilicus as the remains of the primary wood and the small
strands as leaf-traces supplying the branch.
Page 164
Fig. 158. Diagrammatic section through the base of a branch to illustrate the Branch theory
of the Ulodendroid scar. (After Watson.)
In the diagrammatic section shown in fig. 158 the outer cortex of the
main stem is represented by oc 1; this consists of secondary tissue. The
corresponding tissue in the branch is seen at oc 2. The stele of the stem is
shown at Tr. St. and that of the branch at Br. St.; lt, lt, mark the position of
the leaf-traces. If we assume the branch to be detached along the line LS,
the depression would show numerous spirally arranged dots representing
the points of exit of leaf-traces and the vascular axis would be exposed in
the umbilicus. This explanation appears to me to be in harmony with the
of the Ulodendroid scar. (After Watson.)
In the diagrammatic section shown in fig. 158 the outer cortex of the
main stem is represented by oc 1; this consists of secondary tissue. The
corresponding tissue in the branch is seen at oc 2. The stele of the stem is
shown at Tr. St. and that of the branch at Br. St.; lt, lt, mark the position of
the leaf-traces. If we assume the branch to be detached along the line LS,
the depression would show numerous spirally arranged dots representing
the points of exit of leaf-traces and the vascular axis would be exposed in
the umbilicus. This explanation appears to me to be in harmony with the
Page 165
surface-features of Ulodendron scars on both Bothrodendron and
Lepidodendron stems. The occasional occurrence of leaf-cushions on a
portion of a Ulodendron scar is a difficulty on the cladoptosis hypothesis.
Assuming that true leaf-cushions occur, their presence may, as Watson
suggests, be due to the folding back of a piece of the outer cortex of the
branch which has been “crushed down on to the area of the scar[301].”
Since this account was written a note has been published by M. Renier[302]
in which he describes a specimen of Bothrodendron from Liège, one face of
which shows a projecting Ulodendroid scar with an excentric umbilicus. On
the other face is a dichotomously branched shoot with surface-features
corresponding to those on the scar; the evidence that the scar represents the
base of the branch is described as indisputable.
Stur[303] held the view that the depressions on Ulodendron stems represent
the places of attachment of special shoots comparable with the bulbils of
Lycopodium Selago, or, it may be added, with the short branches
occasionally produced on Cycas stems. If the depressions were formed by
the pressure of the bases of cones, it is clear that the size of the cavity must
be an index of the diameter of the cone. The larger Ulodendron scars exceed
in diameter the base of any known lepidodendroid strobilus. Another
obvious difficulty, which has not been overlooked by Kidston who holds
that the scars were produced by sessile cones, is that in Lepidodendron
Veltheimianum strobili were borne at the tips of slender branches; the same
difficulty is presented by Bothrodendron (Fig. 213). It is unlikely that two
types of strobili were produced on the same plant, particularly as the cone
of L. Veltheimianum was heterosporous.
The cones of certain species of Pinus remain attached to the tree for
many years and their bases become embedded in the stem; this is
particularly well shown in the drawing of a cone of Pinus clausa (fig. 159),
for which I am indebted to Mr Sudworth, Dendrologist in the United States
Forest Service. Mr Sudworth has drawn my attention to P. attenuata and P.
muricata in illustration of the same phenomenon[304]. The example shown in
fig. 159 cannot, however, be matched by any known specimen of
Ulodendron; in the case of the depressions on the stem of a Pine the cone-
base fits the circular scar, but in the fossil stems it is practically certain that
this was not the case.
Lepidodendron stems. The occasional occurrence of leaf-cushions on a
portion of a Ulodendron scar is a difficulty on the cladoptosis hypothesis.
Assuming that true leaf-cushions occur, their presence may, as Watson
suggests, be due to the folding back of a piece of the outer cortex of the
branch which has been “crushed down on to the area of the scar[301].”
Since this account was written a note has been published by M. Renier[302]
in which he describes a specimen of Bothrodendron from Liège, one face of
which shows a projecting Ulodendroid scar with an excentric umbilicus. On
the other face is a dichotomously branched shoot with surface-features
corresponding to those on the scar; the evidence that the scar represents the
base of the branch is described as indisputable.
Stur[303] held the view that the depressions on Ulodendron stems represent
the places of attachment of special shoots comparable with the bulbils of
Lycopodium Selago, or, it may be added, with the short branches
occasionally produced on Cycas stems. If the depressions were formed by
the pressure of the bases of cones, it is clear that the size of the cavity must
be an index of the diameter of the cone. The larger Ulodendron scars exceed
in diameter the base of any known lepidodendroid strobilus. Another
obvious difficulty, which has not been overlooked by Kidston who holds
that the scars were produced by sessile cones, is that in Lepidodendron
Veltheimianum strobili were borne at the tips of slender branches; the same
difficulty is presented by Bothrodendron (Fig. 213). It is unlikely that two
types of strobili were produced on the same plant, particularly as the cone
of L. Veltheimianum was heterosporous.
The cones of certain species of Pinus remain attached to the tree for
many years and their bases become embedded in the stem; this is
particularly well shown in the drawing of a cone of Pinus clausa (fig. 159),
for which I am indebted to Mr Sudworth, Dendrologist in the United States
Forest Service. Mr Sudworth has drawn my attention to P. attenuata and P.
muricata in illustration of the same phenomenon[304]. The example shown in
fig. 159 cannot, however, be matched by any known specimen of
Ulodendron; in the case of the depressions on the stem of a Pine the cone-
base fits the circular scar, but in the fossil stems it is practically certain that
this was not the case.
Page 166
Fig. 159. Pinus clausa. ½ nat. size.
There can be little doubt that certain Palaeozoic Lycopods shed their
branches by a method similar to that employed by the Kauri Pine of New
Zealand and by some species of Dicotyledons. The evidence adduced in the
case of Bothrodendron punctatum is a strong argument in favour of
extending the same explanation to other Ulodendron shoots.
There can be little doubt that certain Palaeozoic Lycopods shed their
branches by a method similar to that employed by the Kauri Pine of New
Zealand and by some species of Dicotyledons. The evidence adduced in the
case of Bothrodendron punctatum is a strong argument in favour of
extending the same explanation to other Ulodendron shoots.
Page 167
Fig. 160.
A. Lepidophloios scoticus Kidst. From a specimen from the Calciferous Sandstone,
Midlothian, in Dr Kidston’s Collection; rather less than ⅓ nat. size.
B. L. scoticus cone. From a specimen from the Calciferous Sandstone of Midlothian
in Dr Kidston’s Collection; slightly reduced.
b. Halonia.
The branched axis with Lepidophloios leaf-cushions, represented in fig.
160, A, illustrates a special form of shoot described by Lindley and
Hutton[305] under the generic name Halonia. The original specimens referred
to this genus are decorticated axes showing remains of Lepidodendroid
leaf-cushions. The spirally disposed circular scars in the specimen of
Halonia (Lepidophloios scoticus[306]) shown in fig. 160 constitute the
characteristic feature of the genus; they may have the form, as in fig. 160,
A, of circular discs with a central umbilicus marking the position of a
A. Lepidophloios scoticus Kidst. From a specimen from the Calciferous Sandstone,
Midlothian, in Dr Kidston’s Collection; rather less than ⅓ nat. size.
B. L. scoticus cone. From a specimen from the Calciferous Sandstone of Midlothian
in Dr Kidston’s Collection; slightly reduced.
b. Halonia.
The branched axis with Lepidophloios leaf-cushions, represented in fig.
160, A, illustrates a special form of shoot described by Lindley and
Hutton[305] under the generic name Halonia. The original specimens referred
to this genus are decorticated axes showing remains of Lepidodendroid
leaf-cushions. The spirally disposed circular scars in the specimen of
Halonia (Lepidophloios scoticus[306]) shown in fig. 160 constitute the
characteristic feature of the genus; they may have the form, as in fig. 160,
A, of circular discs with a central umbilicus marking the position of a
Page 168
vascular strand, or, as in the sandstone cast of Halonia tortuosa shown in
fig. 161[307], they may appear as prominent tubercles. The latter example
illustrates the condition characteristic of partially decorticated stems.
Fig. 161. Halonia tortuosa L. and H. From a specimen in Dr Kidston’s Collection, from the
Lower Coal-measures of Ayrshire (No. 1561); ⅔ nat. size.
In 1883 Williamson[308] described a specimen, now in the Leeds Museum,
which convinced him that Halonia is merely a special form of
Lepidodendron concerned with the production of fertile shoots or strobili.
Feistmantel[309] also recognised that Halonia regularis is identical in the
form of the cushions with the type known as Lepidophloios laricinus. It is
worthy of note that under the name Halonia, Feistmantel[310] figured a piece
of decorticated axis characterised by two rows instead of the usual spiral
series of large cup-shaped scars. Recent researches have, however, tended
to break down the distinction between Ulodendron and Halonia founded
fig. 161[307], they may appear as prominent tubercles. The latter example
illustrates the condition characteristic of partially decorticated stems.
Fig. 161. Halonia tortuosa L. and H. From a specimen in Dr Kidston’s Collection, from the
Lower Coal-measures of Ayrshire (No. 1561); ⅔ nat. size.
In 1883 Williamson[308] described a specimen, now in the Leeds Museum,
which convinced him that Halonia is merely a special form of
Lepidodendron concerned with the production of fertile shoots or strobili.
Feistmantel[309] also recognised that Halonia regularis is identical in the
form of the cushions with the type known as Lepidophloios laricinus. It is
worthy of note that under the name Halonia, Feistmantel[310] figured a piece
of decorticated axis characterised by two rows instead of the usual spiral
series of large cup-shaped scars. Recent researches have, however, tended
to break down the distinction between Ulodendron and Halonia founded
Page 169
respectively on the biseriate and spiral arrangement of the scars or
tubercles.
The interpretation of Halonial branches as cone-bearing members of
Lepidodendroid plants has passed into a generally accepted statement of
fact, but, so far as I know, only one specimen has been figured in which
strobili are seen attached to an Halonia axis. This specimen, described by
Grand’Eury[311] from the coal-field of Gard, is hardly sufficiently well-
preserved to constitute a demonstration of the correctness of the generally
received view, which, as is not unusual, has been repeated by one writer
after another without due regard being paid to the nature of the evidence on
which the statement is based. It may, indeed, be correct to describe Halonial
branches as cone-bearing, but there are certain considerations which make
one pause before unhesitatingly accepting this explanation. The vascular
strand which passes from the central cylinder of the shoot to the tubercle or
scar is composed of a solid rod of xylem distinguished from the main stele
by the absence of a pith. In such petrified peduncles as have been
discovered the stele is of the medullated type. The common occurrence of
strobili terminating slender branches of lepidodendroid plants, though not a
fatal objection to their attachment to Halonial shoots, shows that in many
cases the cones were borne at the tip of leafy shoots. It may be that some of
the Halonial scars are in origin like those of the Ulodendron axes of
Bothrodendron and mark the position of deciduous vegetative branches.
The first account of the anatomy of Halonia we owe to Dawes[312]; this
was followed by a fuller description by Binney[313]. The history of our
knowledge of this type of branch has been given by Carruthers[314], who
expressed the opinion that Halonia is merely a fertile condition of
Lepidophloios and possibly of other lepidodendroid plants. He was also
inclined to regard the Halonial tubercles as younger stages of the larger
scars characteristic of the genus Ulodendron. Williamson’s contributions to
our knowledge of Halonia are of primary importance; he supplied further
proof of the Lepidodendroid nature of these branches and advanced our
knowledge of their anatomy. In an early paper[315] he expressed the view that
the differences on which Halonia and Ulodendron are separated are such as
result from a difference in age and are not of generic importance. In the last
memoir, of which he was sole author, published by the Royal Society[316],
tubercles.
The interpretation of Halonial branches as cone-bearing members of
Lepidodendroid plants has passed into a generally accepted statement of
fact, but, so far as I know, only one specimen has been figured in which
strobili are seen attached to an Halonia axis. This specimen, described by
Grand’Eury[311] from the coal-field of Gard, is hardly sufficiently well-
preserved to constitute a demonstration of the correctness of the generally
received view, which, as is not unusual, has been repeated by one writer
after another without due regard being paid to the nature of the evidence on
which the statement is based. It may, indeed, be correct to describe Halonial
branches as cone-bearing, but there are certain considerations which make
one pause before unhesitatingly accepting this explanation. The vascular
strand which passes from the central cylinder of the shoot to the tubercle or
scar is composed of a solid rod of xylem distinguished from the main stele
by the absence of a pith. In such petrified peduncles as have been
discovered the stele is of the medullated type. The common occurrence of
strobili terminating slender branches of lepidodendroid plants, though not a
fatal objection to their attachment to Halonial shoots, shows that in many
cases the cones were borne at the tip of leafy shoots. It may be that some of
the Halonial scars are in origin like those of the Ulodendron axes of
Bothrodendron and mark the position of deciduous vegetative branches.
The first account of the anatomy of Halonia we owe to Dawes[312]; this
was followed by a fuller description by Binney[313]. The history of our
knowledge of this type of branch has been given by Carruthers[314], who
expressed the opinion that Halonia is merely a fertile condition of
Lepidophloios and possibly of other lepidodendroid plants. He was also
inclined to regard the Halonial tubercles as younger stages of the larger
scars characteristic of the genus Ulodendron. Williamson’s contributions to
our knowledge of Halonia are of primary importance; he supplied further
proof of the Lepidodendroid nature of these branches and advanced our
knowledge of their anatomy. In an early paper[315] he expressed the view that
the differences on which Halonia and Ulodendron are separated are such as
result from a difference in age and are not of generic importance. In the last
memoir, of which he was sole author, published by the Royal Society[316],
Page 170
Williamson brought forward further evidence in support of this well-
founded opinion.
That the fossils known as Halonia are branches of a lepidodendroid plant
is at least certain, and it is probable that the lateral branches which they
bore were fertile, though satisfactory proof of this is lacking. We know also
that Halonia branches are characterised by the Lepidophloios form of leaf-
cushion; there is, however, no sufficient reason to assume that such
branches were never attached to stems with the cushions of the
Lepidodendron form. The further question, namely whether Williamson was
correct in his contention as to the absence of any essential distinction
between Ulodendron and Halonia, does not admit of an unchallenged
answer. In 1903 Weiss[317] described the anatomy of a specimen of a
biseriate Halonia branch of Lepidophloios. The form of the leaf-cushions is
unfortunately not very well preserved, but Weiss figures other specimens
with two rows of tubercles on which the leaf-cushions are sufficiently
distinct to justify a comparison with those of Lepidophloios. He believes
with Williamson that it is the presence of tubercles in place of scars which
distinguishes Halonia from Ulodendron, and that the arrangement of the
tubercles or scars is a matter of little importance. He expresses the opinion
justified by the evidence available that the absence or presence of tubercles
is merely due to accidents of preservation or, one may add, to difference in
age. Kidston[318] dissents from Weiss’s description of his specimen as a
biseriate Halonia; he regards it as a Ulodendron branch of Sigillaria
discophora (König). Until specimens with more clearly preserved external
features are forthcoming it is impossible to settle the point in dispute, but on
the facts before us there would seem to be a prima facie case in favour of
Weiss’s contention.
The designation Halonia may be retained as a descriptive term for
Lepidodendroid shoots characterised by spirally disposed scars or tubercles
and bearing leaf-cushions of the Lepidophloios type. In the case of
specimens showing prominent tubercles, the superficial tissues are usually
absent and, as in the fossil represented in fig. 161, the name Halonia does
not necessarily imply the presence of leaf-cushions of a particular type.
vii. Anatomical characters of Vegetative Lepidodendron shoots
(Lepidodendron and Lepidophloios).
founded opinion.
That the fossils known as Halonia are branches of a lepidodendroid plant
is at least certain, and it is probable that the lateral branches which they
bore were fertile, though satisfactory proof of this is lacking. We know also
that Halonia branches are characterised by the Lepidophloios form of leaf-
cushion; there is, however, no sufficient reason to assume that such
branches were never attached to stems with the cushions of the
Lepidodendron form. The further question, namely whether Williamson was
correct in his contention as to the absence of any essential distinction
between Ulodendron and Halonia, does not admit of an unchallenged
answer. In 1903 Weiss[317] described the anatomy of a specimen of a
biseriate Halonia branch of Lepidophloios. The form of the leaf-cushions is
unfortunately not very well preserved, but Weiss figures other specimens
with two rows of tubercles on which the leaf-cushions are sufficiently
distinct to justify a comparison with those of Lepidophloios. He believes
with Williamson that it is the presence of tubercles in place of scars which
distinguishes Halonia from Ulodendron, and that the arrangement of the
tubercles or scars is a matter of little importance. He expresses the opinion
justified by the evidence available that the absence or presence of tubercles
is merely due to accidents of preservation or, one may add, to difference in
age. Kidston[318] dissents from Weiss’s description of his specimen as a
biseriate Halonia; he regards it as a Ulodendron branch of Sigillaria
discophora (König). Until specimens with more clearly preserved external
features are forthcoming it is impossible to settle the point in dispute, but on
the facts before us there would seem to be a prima facie case in favour of
Weiss’s contention.
The designation Halonia may be retained as a descriptive term for
Lepidodendroid shoots characterised by spirally disposed scars or tubercles
and bearing leaf-cushions of the Lepidophloios type. In the case of
specimens showing prominent tubercles, the superficial tissues are usually
absent and, as in the fossil represented in fig. 161, the name Halonia does
not necessarily imply the presence of leaf-cushions of a particular type.
vii. Anatomical characters of Vegetative Lepidodendron shoots
(Lepidodendron and Lepidophloios).
Page 171
The type already described under the name Lepidodendron vasculare
differs from those dealt with in the following pages chiefly in the anatomy
of the stele. The simplest and probably most primitive type of
Lepidodendron stem is that in which the xylem forms a solid rod; the type
of stele most frequently represented is that of L. Harcourtii, L. fuliginosum,
and other species in which the diameter of the stele is greater and a cylinder
of primary xylem encloses a comparatively large parenchymatous pith.
1. Lepidodendron esnostense, Renault[319].
This species was founded by Renault on petrified specimens from the
Culm beds of Esnost in France. The surface of a young twig bears
prominent leaf-cushions of elongated rhomboidal form similar to those of
Lepidodendron obovatum (fig. 173) and other species. In older branches the
primary cortex is replaced by a considerable thickness of radially disposed
secondary cortical tissue which, as shown in tangential section, consists of a
reticulum of elongated pointed elements with comparatively thick walls
enclosing meshes filled with large-celled parenchyma. It is worthy of note
that if such a branch were exposed to decay, the earlier destruction of the
more delicate tissue in the meshes of the secondary cortex would produce a
series of oval depressions, corresponding to the parenchymatous areas,
separated by a projecting reticulum of the more resistant elements: a cast of
this partially decayed surface would be indistinguishable from that of some
types of Sigillaria or of a Lyginodendron. The inner regions of the cortex of
the type-specimens have not been preserved. The xylem, which is the only
part of the stele represented, has the form of a protostele or solid cylinder of
scalariform tracheids with peripheral groups of narrower protoxylem
elements which mark the points of exit of the leaf-traces: in a branch 1–2
cm. wide the xylem column has a diameter of 3 mm. The small leaves (fig.
143, B, C), similar to those of a Sigillaria, are sub-rhomboidal in section
near the base and approximately circular near the apex[320]. The mesophyll
consists of palisade cells having the appearance of typical chlorophyll-
tissue. The heterosporous strobili attributed to this species bore
microsporangia on the upper and megasporangia on the lower sporophylls;
the megaspores, of which a considerable number occur in each
megasporangium, are identical in size with those of another Culm form,
Lepidodendron rhodumnense. Some of these have retained traces of
differs from those dealt with in the following pages chiefly in the anatomy
of the stele. The simplest and probably most primitive type of
Lepidodendron stem is that in which the xylem forms a solid rod; the type
of stele most frequently represented is that of L. Harcourtii, L. fuliginosum,
and other species in which the diameter of the stele is greater and a cylinder
of primary xylem encloses a comparatively large parenchymatous pith.
1. Lepidodendron esnostense, Renault[319].
This species was founded by Renault on petrified specimens from the
Culm beds of Esnost in France. The surface of a young twig bears
prominent leaf-cushions of elongated rhomboidal form similar to those of
Lepidodendron obovatum (fig. 173) and other species. In older branches the
primary cortex is replaced by a considerable thickness of radially disposed
secondary cortical tissue which, as shown in tangential section, consists of a
reticulum of elongated pointed elements with comparatively thick walls
enclosing meshes filled with large-celled parenchyma. It is worthy of note
that if such a branch were exposed to decay, the earlier destruction of the
more delicate tissue in the meshes of the secondary cortex would produce a
series of oval depressions, corresponding to the parenchymatous areas,
separated by a projecting reticulum of the more resistant elements: a cast of
this partially decayed surface would be indistinguishable from that of some
types of Sigillaria or of a Lyginodendron. The inner regions of the cortex of
the type-specimens have not been preserved. The xylem, which is the only
part of the stele represented, has the form of a protostele or solid cylinder of
scalariform tracheids with peripheral groups of narrower protoxylem
elements which mark the points of exit of the leaf-traces: in a branch 1–2
cm. wide the xylem column has a diameter of 3 mm. The small leaves (fig.
143, B, C), similar to those of a Sigillaria, are sub-rhomboidal in section
near the base and approximately circular near the apex[320]. The mesophyll
consists of palisade cells having the appearance of typical chlorophyll-
tissue. The heterosporous strobili attributed to this species bore
microsporangia on the upper and megasporangia on the lower sporophylls;
the megaspores, of which a considerable number occur in each
megasporangium, are identical in size with those of another Culm form,
Lepidodendron rhodumnense. Some of these have retained traces of
Page 172
prothallus tissue, and in one spore Renault figures what he regards as an
archegonium: the drawing is by no means convincing.
2. Lepidodendron rhodumnense, Renault[321].
The species from the Culm of Combres (Loire) agrees in its solid xylem
cylinder and in the differentiation of the secondary cortex, as also in the
association of two kinds of spore, with Lepidodendron esnostense. A
comparison of the leaves of the two types reveals certain differences which
may be of specific rank, but, apart from minor differences, these Culm
species may be classed under one anatomical type.
3. Lepidodendron saalfeldense, Solms-Laubach[322].
This Devonian species was founded on a specimen 3 × 2·5 cm. broad at
the base, which shows the stumps of four branches recalling the
dichotomously branched arms of Stigmaria and Pleuromeia. If these are in
reality the remains of Stigmaria-like horizontal branches the species affords
an interesting example of a Lepidodendron axis with a subterranean
rhizome of the type which has been found in several Sigillarian stems. In
the upper end of the axis the stele consists of a solid strand of xylem which
is not sufficiently well preserved to show the position of the protoxylem
groups. A transverse section taken near the base reveals a type of stele
differing from that at the upper end in being composed of radially disposed
tracheids and in its resemblance to the stele of Stigmaria.
4. Lepidodendron fuliginosum, Williamson. Figs. 162–172, 179, E.
archegonium: the drawing is by no means convincing.
2. Lepidodendron rhodumnense, Renault[321].
The species from the Culm of Combres (Loire) agrees in its solid xylem
cylinder and in the differentiation of the secondary cortex, as also in the
association of two kinds of spore, with Lepidodendron esnostense. A
comparison of the leaves of the two types reveals certain differences which
may be of specific rank, but, apart from minor differences, these Culm
species may be classed under one anatomical type.
3. Lepidodendron saalfeldense, Solms-Laubach[322].
This Devonian species was founded on a specimen 3 × 2·5 cm. broad at
the base, which shows the stumps of four branches recalling the
dichotomously branched arms of Stigmaria and Pleuromeia. If these are in
reality the remains of Stigmaria-like horizontal branches the species affords
an interesting example of a Lepidodendron axis with a subterranean
rhizome of the type which has been found in several Sigillarian stems. In
the upper end of the axis the stele consists of a solid strand of xylem which
is not sufficiently well preserved to show the position of the protoxylem
groups. A transverse section taken near the base reveals a type of stele
differing from that at the upper end in being composed of radially disposed
tracheids and in its resemblance to the stele of Stigmaria.
4. Lepidodendron fuliginosum, Williamson. Figs. 162–172, 179, E.
Page 173
1871. Lepidodendron Harcourtii, Binney, Palæont. Soc., p. 48, Pl.
vii. fig. 6.
1872. Halonia regularis, Binney, Palæont. Soc., p. 89, Pl. xv.
1881. Lepidodendron Harcourtii, Williamson, Phil. Trans. Roy.
Soc., Vol. 172, p. 288, Pls. xlix–lii.
1887. Lepidodendron fuliginosum, Williamson, Proc. Roy. Soc., Vol.
xlii. p. 6.
1891. Lepidodendron Williamsoni, Solms-Laubach, Fossil Botany,
p. 226.
1893. Lepidophloios fuliginosus, Kidston, Trans. Roy. Soc.
Edinburgh, Vol. xxxviii. p. 548.
The name Lepidodendron fuliginosum was proposed by Williamson in
1887 for petrified stems previously included by him in Witham’s species L.
Harcourtii, but subsequently recognised as a distinct type characterised by
“the greater uniformity in the composition of the entire cortex” and by other
features some of which do not constitute distinctive characters. The species
agrees with L. Harcourtii and with L. Veltheimianum in having a medullated
stele; it is distinguished not only by the more frequent preservation of the
middle cortex, a fact due to a difference in minute structure, but chiefly by
the peculiar structure of the secondary tissue added to the stele; this is in
part composed of radial series of parenchymatous cells and of a varying
amount of tracheal tissue the elements of which are narrower than in other
species and are characterised also by their sinuous vertical course. As is
pointed out in the sequel, the anatomical features of L. fuliginosum, as at
present understood, are not confined to one type of Lepidodendron stem.
Specimens have been described with leaf-cushions of the form
characteristic of L. aculeatum, L. obovatum and Lepidophloios combined
with the anatomical features of Williamson’s species: it is possible that the
two species L. obovatum and L. aculeatum are not really distinct[323], but it
is certain that shoots with both the Lepidodendron and Lepidophloios
cushions may have the same type of anatomical structure.
A more detailed knowledge of the structural features of Lepidodendron
shoots may enable us to define anatomical species with more exactness than
is possible at present. There can, however, be little doubt that well-marked
vii. fig. 6.
1872. Halonia regularis, Binney, Palæont. Soc., p. 89, Pl. xv.
1881. Lepidodendron Harcourtii, Williamson, Phil. Trans. Roy.
Soc., Vol. 172, p. 288, Pls. xlix–lii.
1887. Lepidodendron fuliginosum, Williamson, Proc. Roy. Soc., Vol.
xlii. p. 6.
1891. Lepidodendron Williamsoni, Solms-Laubach, Fossil Botany,
p. 226.
1893. Lepidophloios fuliginosus, Kidston, Trans. Roy. Soc.
Edinburgh, Vol. xxxviii. p. 548.
The name Lepidodendron fuliginosum was proposed by Williamson in
1887 for petrified stems previously included by him in Witham’s species L.
Harcourtii, but subsequently recognised as a distinct type characterised by
“the greater uniformity in the composition of the entire cortex” and by other
features some of which do not constitute distinctive characters. The species
agrees with L. Harcourtii and with L. Veltheimianum in having a medullated
stele; it is distinguished not only by the more frequent preservation of the
middle cortex, a fact due to a difference in minute structure, but chiefly by
the peculiar structure of the secondary tissue added to the stele; this is in
part composed of radial series of parenchymatous cells and of a varying
amount of tracheal tissue the elements of which are narrower than in other
species and are characterised also by their sinuous vertical course. As is
pointed out in the sequel, the anatomical features of L. fuliginosum, as at
present understood, are not confined to one type of Lepidodendron stem.
Specimens have been described with leaf-cushions of the form
characteristic of L. aculeatum, L. obovatum and Lepidophloios combined
with the anatomical features of Williamson’s species: it is possible that the
two species L. obovatum and L. aculeatum are not really distinct[323], but it
is certain that shoots with both the Lepidodendron and Lepidophloios
cushions may have the same type of anatomical structure.
A more detailed knowledge of the structural features of Lepidodendron
shoots may enable us to define anatomical species with more exactness than
is possible at present. There can, however, be little doubt that well-marked
Page 174
anatomical features may be associated with more than one specific form of
shoot as defined by the form of the leaf-cushions.
Solms-Laubach proposed the name Lepidodendron Williamsoni for the
anatomical type L. fuliginosum of Williamson, but the latter name has been
generally adopted.
In the following account special attention is directed to the nature and
origin of the secondary stelar tissue and to the secretory zone, as difference
of opinion exists as to the interpretation of these features. Among the best
examples of shoots of Lepidodendron fuliginosum without secondary tissue
or in which it is feebly developed are those originally described by Binney.
The stele includes a large parenchymatous pith, the cells of which
frequently show signs of recent division, a feature observed also in the pith
of the large stem of L. Wünschianum, represented in figs. 181, 182. The
primary xylem cylinder has an irregularly crenulate outer edge like that of
L. Wünschianum and L. Harcourtii and the protoxylem elements occupy an
exarch position. Isodiametric reticulately-pitted elements are met with both
on the inner and outer edge of the xylem.
Fig. 162. Lepidodendron fuliginosum. Part of the stele in transverse section. (Binney
Collection, Sedgwick Museum, Cambridge.)
shoot as defined by the form of the leaf-cushions.
Solms-Laubach proposed the name Lepidodendron Williamsoni for the
anatomical type L. fuliginosum of Williamson, but the latter name has been
generally adopted.
In the following account special attention is directed to the nature and
origin of the secondary stelar tissue and to the secretory zone, as difference
of opinion exists as to the interpretation of these features. Among the best
examples of shoots of Lepidodendron fuliginosum without secondary tissue
or in which it is feebly developed are those originally described by Binney.
The stele includes a large parenchymatous pith, the cells of which
frequently show signs of recent division, a feature observed also in the pith
of the large stem of L. Wünschianum, represented in figs. 181, 182. The
primary xylem cylinder has an irregularly crenulate outer edge like that of
L. Wünschianum and L. Harcourtii and the protoxylem elements occupy an
exarch position. Isodiametric reticulately-pitted elements are met with both
on the inner and outer edge of the xylem.
Fig. 162. Lepidodendron fuliginosum. Part of the stele in transverse section. (Binney
Collection, Sedgwick Museum, Cambridge.)
Page 175
Fig. 163. Lepidodendron fuliginosum. Longitudinal section. (Binney Collection, Cambridge.)
Figs. 162 and 163 illustrate the structure of the outer portion of the xylem
and adjacent tissues in a section of a shoot 3·8 cm. × 2·5 cm. in diameter,
which is in the act of branching, as shown by the occurrence of two steles
of equal size. A figure of the complete section will be found in Binney’s
memoir[324], and additional illustrations were published in 1899[325].
Figs. 162 and 163 illustrate the structure of the outer portion of the xylem
and adjacent tissues in a section of a shoot 3·8 cm. × 2·5 cm. in diameter,
which is in the act of branching, as shown by the occurrence of two steles
of equal size. A figure of the complete section will be found in Binney’s
memoir[324], and additional illustrations were published in 1899[325].
Page 176
Fig. 164. Lepidodendron fuliginosum. Leaf-trace. (Binney Collection, Cambridge.)
The primary xylem (figs. 162, 163, x) is succeeded by 2–3 rows of
polygonal cells with dark contents and associated with isodiametric
tracheae: these pass into clearer parenchymatous tissue, a, characterised by
the arrangement of the cells in vertical series, to which the term
meristematic zone has been applied. The secretory zone, s, abutting on the
meristematic zone, consists of more or less disorganised parenchymatous
cells and broader and more elongated spaces; it is interrupted here and there
by an outgoing leaf-trace, as at lt 1 and lt 2 in fig. 162. The secretory zone is
succeeded by a homogeneous inner cortex like that described in L.
vasculare; part of this region is seen at the upper edge of fig. 162. The
broad middle cortex, which is separated from the inner cortex by a sharply
The primary xylem (figs. 162, 163, x) is succeeded by 2–3 rows of
polygonal cells with dark contents and associated with isodiametric
tracheae: these pass into clearer parenchymatous tissue, a, characterised by
the arrangement of the cells in vertical series, to which the term
meristematic zone has been applied. The secretory zone, s, abutting on the
meristematic zone, consists of more or less disorganised parenchymatous
cells and broader and more elongated spaces; it is interrupted here and there
by an outgoing leaf-trace, as at lt 1 and lt 2 in fig. 162. The secretory zone is
succeeded by a homogeneous inner cortex like that described in L.
vasculare; part of this region is seen at the upper edge of fig. 162. The
broad middle cortex, which is separated from the inner cortex by a sharply
Page 177
defined boundary, is composed of rather small lacunar parenchymatous
tissue consisting of sinuous tubular elements interspersed among
isodiametric cells of various sizes (fig. 166, p). In the middle cortical region
the leaf-traces pursue an almost horizontal course; one is shown in fig. 164,
in oblique longitudinal section, in a reversed position; the xylem, x, should
be on the inner side of the secretory tissue, s. The clear space between the
two parts of the vascular bundle was originally occupied by a few layers of
parenchymatous cells, as seen in the transverse sections, figs. 165 and 166.
In some specimens the leaf-traces pass through the middle cortex in a much
more vertical course, as shown by the section represented in fig. 165. This
section illustrates the structure of a typical leaf-trace with unusual
clearness; it shows the tangentially elongated group of xylem, the strand of
tissue which occupies the position of phloem, s (to which the term secretory
zone is applied), the compact parenchyma between the two parts of the
bundle, and surrounding the whole a narrow sheath sharply contrasted by
the smaller and more uniform size of the cells from the middle cortex, a few
cells of which are seen in the photograph. The middle cortex shows a well-
defined junction with the more compact outer cortical region, which
consists of primary parenchyma passing externally into a zone of
phelloderm composed of thick-walled and more elongated cells. A
noticeable feature in many Lepidodendron shoots is the occurrence of a
circle of strands of secretory cells often surrounding fairly large ducts just
internal to the edge of phelloderm: similar strands form irregularly
concentric circles, as was pointed out in the case of L. vasculare, in the
phelloderm itself.
tissue consisting of sinuous tubular elements interspersed among
isodiametric cells of various sizes (fig. 166, p). In the middle cortical region
the leaf-traces pursue an almost horizontal course; one is shown in fig. 164,
in oblique longitudinal section, in a reversed position; the xylem, x, should
be on the inner side of the secretory tissue, s. The clear space between the
two parts of the vascular bundle was originally occupied by a few layers of
parenchymatous cells, as seen in the transverse sections, figs. 165 and 166.
In some specimens the leaf-traces pass through the middle cortex in a much
more vertical course, as shown by the section represented in fig. 165. This
section illustrates the structure of a typical leaf-trace with unusual
clearness; it shows the tangentially elongated group of xylem, the strand of
tissue which occupies the position of phloem, s (to which the term secretory
zone is applied), the compact parenchyma between the two parts of the
bundle, and surrounding the whole a narrow sheath sharply contrasted by
the smaller and more uniform size of the cells from the middle cortex, a few
cells of which are seen in the photograph. The middle cortex shows a well-
defined junction with the more compact outer cortical region, which
consists of primary parenchyma passing externally into a zone of
phelloderm composed of thick-walled and more elongated cells. A
noticeable feature in many Lepidodendron shoots is the occurrence of a
circle of strands of secretory cells often surrounding fairly large ducts just
internal to the edge of phelloderm: similar strands form irregularly
concentric circles, as was pointed out in the case of L. vasculare, in the
phelloderm itself.
Page 178
Fig. 165. Lepidodendron fuliginosum. Leaf-trace: x, xylem; s, secretory zone. (Binney
Collection, Cambridge.)
Collection, Cambridge.)
Page 179
Fig. 166. Lepidodendron fuliginosum. Leaf-trace: p, parichnos. (Binney Collection,
Cambridge.)
Fig. 166 shows a leaf-trace in the outer cortex accompanied by its
crescent-shaped parichnos, p, derived from the middle cortex and by means
of which the outer cortex and the lamina of the leaves are connected with
the inner region of the shoot. This lacunar middle cortex and parichnos
doubtless constitute an aerating tissue-system which after leaf-fall is
exposed directly to the air at the ends of the parichnos arms on the leaf-
scars.
Some of the sections in the Binney Collection (Sedgwick Museum,
Cambridge) show early stages in the production of secondary xylem: in the
section represented in fig. 167 the secretory zone is succeeded on its inner
face by a zone of radially elongated cells, m, which are clearly in a
meristematic condition. The same section shows also the more radially
extended form of the xylem of a leaf-trace with its internal protoxylem, px,
in contrast to the tangentially elongated form which is assumed during its
passage through the cortex (cf. figs. 165, 166).
Cambridge.)
Fig. 166 shows a leaf-trace in the outer cortex accompanied by its
crescent-shaped parichnos, p, derived from the middle cortex and by means
of which the outer cortex and the lamina of the leaves are connected with
the inner region of the shoot. This lacunar middle cortex and parichnos
doubtless constitute an aerating tissue-system which after leaf-fall is
exposed directly to the air at the ends of the parichnos arms on the leaf-
scars.
Some of the sections in the Binney Collection (Sedgwick Museum,
Cambridge) show early stages in the production of secondary xylem: in the
section represented in fig. 167 the secretory zone is succeeded on its inner
face by a zone of radially elongated cells, m, which are clearly in a
meristematic condition. The same section shows also the more radially
extended form of the xylem of a leaf-trace with its internal protoxylem, px,
in contrast to the tangentially elongated form which is assumed during its
passage through the cortex (cf. figs. 165, 166).
Page 180
Fig. 167. Lepidodendron fuliginosum. (Binney Collection, Cambridge.)
Some sections of Lepidodendron fuliginosum in the Manchester
University Collection are of special interest from the point of view of the
method of secondary thickening. In the section reproduced in fig. 168, B,
the meristematic zone is seen to consist in part of radially elongated
elements, m, with parallel cross-walls evidently of recent origin. The same
tissue is shown also in fig. 168, C, a, D, a, and in fig. 169, A, a This band of
meristem, which we may speak of as the cambium, occurs in the outer
region of the meristematic zone immediately internal to the secretory zone,
sc.
Some sections of Lepidodendron fuliginosum in the Manchester
University Collection are of special interest from the point of view of the
method of secondary thickening. In the section reproduced in fig. 168, B,
the meristematic zone is seen to consist in part of radially elongated
elements, m, with parallel cross-walls evidently of recent origin. The same
tissue is shown also in fig. 168, C, a, D, a, and in fig. 169, A, a This band of
meristem, which we may speak of as the cambium, occurs in the outer
region of the meristematic zone immediately internal to the secretory zone,
sc.
Page 181
Fig. 168.
A. Lepidodendron vasculare. (Botany School, Cambridge.)
B. Lepidodendron fuliginosum. (From a specimen from Shore, Lancashire, in the
Cambridge Botany School Collection).
C. L. fuliginosum. (“Biseriate Halonia” of Weiss No. 257, Manchester University
Museum.)
D. L. fuliginosum. (Manchester Univ. Museum.)
The result of the activity of this cambium band is the production of
secondary parenchyma and tracheal tissue. In fig. 179, E, drawn from a
portion of the section represented in fig. 168, B, a projecting arm of primary
xylem is seen at x; this is followed by 2–3 layers of parenchymatous cells,
some of which have dark contents, and beyond this is seen a group of
secondary elements, tr, cut across somewhat obliquely, which are evidently
products of the cambial cells on the inner margin of the secretory zone, sc.
The longitudinal section (fig. 169, D) shows the cambial cells, a, next the
A. Lepidodendron vasculare. (Botany School, Cambridge.)
B. Lepidodendron fuliginosum. (From a specimen from Shore, Lancashire, in the
Cambridge Botany School Collection).
C. L. fuliginosum. (“Biseriate Halonia” of Weiss No. 257, Manchester University
Museum.)
D. L. fuliginosum. (Manchester Univ. Museum.)
The result of the activity of this cambium band is the production of
secondary parenchyma and tracheal tissue. In fig. 179, E, drawn from a
portion of the section represented in fig. 168, B, a projecting arm of primary
xylem is seen at x; this is followed by 2–3 layers of parenchymatous cells,
some of which have dark contents, and beyond this is seen a group of
secondary elements, tr, cut across somewhat obliquely, which are evidently
products of the cambial cells on the inner margin of the secretory zone, sc.
The longitudinal section (fig. 169, D) shows the cambial cells, a, next the
Page 182
secretory zone, sc, passing internally into crushed and imperfectly
preserved elongated elements which are presumably miniature tracheae, and
these are succeeded by older and more completely lignified xylem
elements, x. In larger shoots the amount of secondary tissue is considerably
greater; it may consist almost entirely of short-celled parenchyma (fig. 168,
C, from x to sc), or it may include a large proportion of radially disposed
and vertically elongated tracheae (fig. 168, D, x2, and fig. 170, A, x2), or it
may consist of parenchyma containing scattered groups of tracheae (fig.
169, A, x2)[326].
preserved elongated elements which are presumably miniature tracheae, and
these are succeeded by older and more completely lignified xylem
elements, x. In larger shoots the amount of secondary tissue is considerably
greater; it may consist almost entirely of short-celled parenchyma (fig. 168,
C, from x to sc), or it may include a large proportion of radially disposed
and vertically elongated tracheae (fig. 168, D, x2, and fig. 170, A, x2), or it
may consist of parenchyma containing scattered groups of tracheae (fig.
169, A, x2)[326].
Page 183
Fig. 169. Lepidodendron fuliginosum.
A, B. (Manchester University Collection. No. Q. 645 A.)
B, C. (Manchester. No. 257.)
D. (Manchester. No. 6.)
Fig. 169, A, is a diagrammatic sketch of the tissues—1 mm. wide—
between the primary xylem, x, and the inner cortex. The primary xylem is
succeeded by short parenchymatous cells followed by a zone of radially
elongated elements passing occasionally into rows of narrow scalariform
tracheae, some of which, owing to their sinuous longitudinal course (fig.
A, B. (Manchester University Collection. No. Q. 645 A.)
B, C. (Manchester. No. 257.)
D. (Manchester. No. 6.)
Fig. 169, A, is a diagrammatic sketch of the tissues—1 mm. wide—
between the primary xylem, x, and the inner cortex. The primary xylem is
succeeded by short parenchymatous cells followed by a zone of radially
elongated elements passing occasionally into rows of narrow scalariform
tracheae, some of which, owing to their sinuous longitudinal course (fig.
Page 184
171, C), are seen in oblique section, as at C, fig. 169, A. At its outer edge
this secondary tissue, x2, consisting of parenchyma and tracheae, passes into
the cambial band (fig. 169, B, a).
Fig. 170. Lepidodendron fuliginosum. (From sections in the Manchester Museum.)
The radial longitudinal section represented in fig. 168, C, is taken from
the fossil described by Weiss as a biseriate Halonia; it agrees sufficiently
closely in structure with others referred to Lepidodendron fuliginosum to be
classed as an example of this anatomical type. A complete transverse
section of the stem measures 9 × 6·3 cm.; the breadth of the tissues between
the edge of the primary xylem and the outer edge of the secretory zone is
2·5 mm. The middle cortical region, characterised by the sooty appearance,
which led Williamson to choose the specific name fuliginosum, is traversed
by the leaf-traces and is sharply differentiated from both the inner and outer
cortex. The longitudinal section (fig. 168, C) shows the outer edge of the
primary xylem, x, abutting on a band of dark and small-celled parenchyma
which passes into the broad zone of secondary tissue, m, the inner region of
which consists of fairly thick-walled elements in radial series passing
externally into the thin-walled cells of the cambial region, a, on the inner
edge of the secretory zone, sc. This section shows also the interruption of
the secretory zone by an outgoing leaf-trace, lt, the lower part of which, sc,
is continued downwards into the secretory zone. The exit of a leaf-trace
produces a gap in the secretory zone of the stem, but not in the xylem. If we
applied the term phloem to the secretory zone—a course adopted by Prof. F.
E. Weiss and some other authors, but which I do not propose to follow—we
this secondary tissue, x2, consisting of parenchyma and tracheae, passes into
the cambial band (fig. 169, B, a).
Fig. 170. Lepidodendron fuliginosum. (From sections in the Manchester Museum.)
The radial longitudinal section represented in fig. 168, C, is taken from
the fossil described by Weiss as a biseriate Halonia; it agrees sufficiently
closely in structure with others referred to Lepidodendron fuliginosum to be
classed as an example of this anatomical type. A complete transverse
section of the stem measures 9 × 6·3 cm.; the breadth of the tissues between
the edge of the primary xylem and the outer edge of the secretory zone is
2·5 mm. The middle cortical region, characterised by the sooty appearance,
which led Williamson to choose the specific name fuliginosum, is traversed
by the leaf-traces and is sharply differentiated from both the inner and outer
cortex. The longitudinal section (fig. 168, C) shows the outer edge of the
primary xylem, x, abutting on a band of dark and small-celled parenchyma
which passes into the broad zone of secondary tissue, m, the inner region of
which consists of fairly thick-walled elements in radial series passing
externally into the thin-walled cells of the cambial region, a, on the inner
edge of the secretory zone, sc. This section shows also the interruption of
the secretory zone by an outgoing leaf-trace, lt, the lower part of which, sc,
is continued downwards into the secretory zone. The exit of a leaf-trace
produces a gap in the secretory zone of the stem, but not in the xylem. If we
applied the term phloem to the secretory zone—a course adopted by Prof. F.
E. Weiss and some other authors, but which I do not propose to follow—we
Page 185
should speak of a phloem foliar-gap as a characteristic feature of a
Lepidodendron shoot. This applies to other species of the genus as well as
to L. fuliginosum.
Fig. 171. Lepidodendron fuliginosum. (From sections in the Manchester Museum.)
Fig. 171, A, shows more clearly the broad zone of secondary parenchyma
with the thinner-walled cambial region, a; the latter is represented on a
larger scale in fig. 171, B. The section shown in fig. 168, D, and in fig. 170,
A, affords an example of a stem in which the secondary tissue consists
largely of narrow scalariform tracheae, x2; the primary stele has a diameter
of 1 cm.; the secondary xylem, x2, forms a fairly broad zone of parenchyma
and tracheal elements through which leaf-traces pass vertically, a fact of
Lepidodendron shoot. This applies to other species of the genus as well as
to L. fuliginosum.
Fig. 171. Lepidodendron fuliginosum. (From sections in the Manchester Museum.)
Fig. 171, A, shows more clearly the broad zone of secondary parenchyma
with the thinner-walled cambial region, a; the latter is represented on a
larger scale in fig. 171, B. The section shown in fig. 168, D, and in fig. 170,
A, affords an example of a stem in which the secondary tissue consists
largely of narrow scalariform tracheae, x2; the primary stele has a diameter
of 1 cm.; the secondary xylem, x2, forms a fairly broad zone of parenchyma
and tracheal elements through which leaf-traces pass vertically, a fact of
Page 186
some interest in comparison with the horizontal course which they pursue
through the medullary rays in the normal secondary wood of L. vasculare
and L. Wünschianum. The secondary tracheae pass gradually into thin-
walled cambial cells (a, fig. 168, D; 170, A) with parallel tangential walls.
Fig. 171, C, shows the sinuous course of the secondary tracheae as seen in
longitudinal section, and a few small groups of parenchymatous cells, mr,
which may be of the nature of medullary rays, enclosed between the
winding scalariform tracheae.
Fig. 172. Lepidodendron fuliginosum. From a section (4 × 3·4 cm.) in the Williamson
Collection, British Museum (No. 379), figured by Williamson, Phil. Trans. R. Soc.
1881, Pl. 52.
The secretory zone of Lepidodendron fuliginosum agrees essentially with
that of other species; it usually presents the appearance shown in fig. 168,
B, sc; fig. 169, B and C; fig. 170, B (longitudinal section); fig. 171, D, sc.
The comparatively large clear spaces which characterise this tissue, as seen
in fig. 168, B, appear to owe their origin to groups of small cells which
gradually break down and give rise to spaces containing remnants of the
disorganised elements, as in fig. 171, D, and fig. 169, B, b. The secretory
tissue seen in fig. 170, B, consists of large and small parenchymatous cells
without any of the broad sacs or spaces such as are shown in fig. 169, C.
Fig. 172 represents a diagrammatic sketch of a transverse section (4 × 3·4
cm. in diameter) of a young shoot from the Lower Coal-Measures of
through the medullary rays in the normal secondary wood of L. vasculare
and L. Wünschianum. The secondary tracheae pass gradually into thin-
walled cambial cells (a, fig. 168, D; 170, A) with parallel tangential walls.
Fig. 171, C, shows the sinuous course of the secondary tracheae as seen in
longitudinal section, and a few small groups of parenchymatous cells, mr,
which may be of the nature of medullary rays, enclosed between the
winding scalariform tracheae.
Fig. 172. Lepidodendron fuliginosum. From a section (4 × 3·4 cm.) in the Williamson
Collection, British Museum (No. 379), figured by Williamson, Phil. Trans. R. Soc.
1881, Pl. 52.
The secretory zone of Lepidodendron fuliginosum agrees essentially with
that of other species; it usually presents the appearance shown in fig. 168,
B, sc; fig. 169, B and C; fig. 170, B (longitudinal section); fig. 171, D, sc.
The comparatively large clear spaces which characterise this tissue, as seen
in fig. 168, B, appear to owe their origin to groups of small cells which
gradually break down and give rise to spaces containing remnants of the
disorganised elements, as in fig. 171, D, and fig. 169, B, b. The secretory
tissue seen in fig. 170, B, consists of large and small parenchymatous cells
without any of the broad sacs or spaces such as are shown in fig. 169, C.
Fig. 172 represents a diagrammatic sketch of a transverse section (4 × 3·4
cm. in diameter) of a young shoot from the Lower Coal-Measures of
Page 187
Lancashire figured by Williamson[327] in 1881 as Lepidodendron Harcourtii.
It shows the features characteristic of L. fuliginosum and is of importance as
affording an example of a shoot giving off a branch from the stele to supply
a lateral axis of the type characteristic of Halonia. The exit of the branch-
stele forms a gap in the main stele; a ramular gap as distinguished from a
foliar gap. The outgoing vascular strand is at first crescentic, but becomes
gradually converted into a solid stele. The primary xylem of the main stele
(black in the figure) consists of a ring six tracheae in breadth; this is
succeeded by a few layers of dark parenchymatous cells and a band of
radially elongated elements, a, which abuts on the secretory zone. The
middle lacunar cortex, c2, with Stigmaria rootlets, s, is fairly well preserved.
In the outer cortex occur several leaf-traces, lt, accompanied by spaces
originally occupied by the parichnos strand, p. A band of secondary cortex,
consisting chiefly of phelloderm, is seen at pd. The prominent leaf-
cushions, some of which show the parichnos, p, appear to be of the
Lepidophloios type.
• • • • •
It remains to consider the external characters of Lepidodendroid shoots
possessing the anatomical features represented by the comprehensive
species Lepidodendron fuliginosum.
Certain sections exhibiting this type of structure were described by
Binney in 1872 as Halonia regularis[328] on evidence supplied by Mr
Dawes, who stated that they were cut from a specimen bearing Halonia
tubercles. The section represented in fig. 172 is no doubt from an Halonia
axis. In 1890 Cash and Lomax[329] stated that they had in their possession a
stem of the L. fuliginosum type with the external features of Lepidophloios;
this identification has been confirmed by Kidston[330] and Weiss[331]. It is,
however, equally clear that certain species with the elongated leaf-cushions
of Lepidodendron must be included among examples of shoots with the
anatomical characters of L. fuliginosum.
It shows the features characteristic of L. fuliginosum and is of importance as
affording an example of a shoot giving off a branch from the stele to supply
a lateral axis of the type characteristic of Halonia. The exit of the branch-
stele forms a gap in the main stele; a ramular gap as distinguished from a
foliar gap. The outgoing vascular strand is at first crescentic, but becomes
gradually converted into a solid stele. The primary xylem of the main stele
(black in the figure) consists of a ring six tracheae in breadth; this is
succeeded by a few layers of dark parenchymatous cells and a band of
radially elongated elements, a, which abuts on the secretory zone. The
middle lacunar cortex, c2, with Stigmaria rootlets, s, is fairly well preserved.
In the outer cortex occur several leaf-traces, lt, accompanied by spaces
originally occupied by the parichnos strand, p. A band of secondary cortex,
consisting chiefly of phelloderm, is seen at pd. The prominent leaf-
cushions, some of which show the parichnos, p, appear to be of the
Lepidophloios type.
• • • • •
It remains to consider the external characters of Lepidodendroid shoots
possessing the anatomical features represented by the comprehensive
species Lepidodendron fuliginosum.
Certain sections exhibiting this type of structure were described by
Binney in 1872 as Halonia regularis[328] on evidence supplied by Mr
Dawes, who stated that they were cut from a specimen bearing Halonia
tubercles. The section represented in fig. 172 is no doubt from an Halonia
axis. In 1890 Cash and Lomax[329] stated that they had in their possession a
stem of the L. fuliginosum type with the external features of Lepidophloios;
this identification has been confirmed by Kidston[330] and Weiss[331]. It is,
however, equally clear that certain species with the elongated leaf-cushions
of Lepidodendron must be included among examples of shoots with the
anatomical characters of L. fuliginosum.
Page 188
Fig. 173. Lepidodendron obovatum. (From a specimen lent by Dr D. H. Scott.)
Dr Scott[332] published in 1906 a short account of the structure of a
specimen from the Lower Coal-Measures of Lancashire, the external
features of which were identified by Kidston with those of Lepidodendron
obovatum Sternb. Dr Scott generously allowed me to have drawings made
from his specimen; these are reproduced in fig. 173. The form of the leaf-
cushion is by no means perfect; there is a well-marked median ridge, and
the small circular scar near the upper end of some of the cushions may
represent the ligular cavity. At the base of the leaf-cushions a cortical
meristem has produced a zone of secondary cortex; at c a second meristem
is seen in the outer cortex: the dark dots in the cortex mark the positions of
leaf-trace bundles. The inner cortex, d, is a more compact tissue
surrounding the imperfectly preserved secretory zone. From the medullated
stele a lateral branch, b, is being given off; its crescentic form becoming
changed to circular as it passes nearer to the surface.
Dr Scott[332] published in 1906 a short account of the structure of a
specimen from the Lower Coal-Measures of Lancashire, the external
features of which were identified by Kidston with those of Lepidodendron
obovatum Sternb. Dr Scott generously allowed me to have drawings made
from his specimen; these are reproduced in fig. 173. The form of the leaf-
cushion is by no means perfect; there is a well-marked median ridge, and
the small circular scar near the upper end of some of the cushions may
represent the ligular cavity. At the base of the leaf-cushions a cortical
meristem has produced a zone of secondary cortex; at c a second meristem
is seen in the outer cortex: the dark dots in the cortex mark the positions of
leaf-trace bundles. The inner cortex, d, is a more compact tissue
surrounding the imperfectly preserved secretory zone. From the medullated
stele a lateral branch, b, is being given off; its crescentic form becoming
changed to circular as it passes nearer to the surface.
Page 189
Fig. 174. Lepidodendron aculeatum. (Cambridge Botany School.)
Fig. 175. Lepidodendron aculeatum. (Cambridge Botany School.)
A type of Lepidodendron, L. Hickii, founded on anatomical characters by
Mr Watson[333], is believed by him to possess leaf-cushions like those of L.
obovatum; if this is so, it is interesting, as he points out, to find two distinct
Fig. 175. Lepidodendron aculeatum. (Cambridge Botany School.)
A type of Lepidodendron, L. Hickii, founded on anatomical characters by
Mr Watson[333], is believed by him to possess leaf-cushions like those of L.
obovatum; if this is so, it is interesting, as he points out, to find two distinct
Page 190
anatomical types associated with one species. Watson thinks it probable that
the “species” L. obovatum includes at least two widely different species.
This merely emphasizes the importance of correlating structure and external
characters as far as available data permit.
Fig. 176. Lepidodendron aculeatum. (Cambridge Botany School.)
The specimen, of which part of the surface is shown in fig. 174, is in all
probability L. aculeatum Sternb. This was described by me in detail in The
Annals of Botany (1906) as another example of the co-existence of the
Lepidodendron fuliginosum type of anatomy with a true Lepidodendron.
The locality of the specimen is not known. The leaf-cushions are 1·5 cm.
long with tapered upper and lower ends; a ligular cavity may be recognised
on some parts of the fossil, also faint indications of leaf-trace scars. The
tubercles (fig. 174, A–C, t) probably represent leaf-traces which the
shrinkage of the superficial tissues has rendered visible in the lower part of
their course. The circular scar, s (fig. B), on the partially decorticated
surface is apparently a wound. The stele is sufficiently well preserved to
justify its reference to L. fuliginosum. The irregularly crenulated edge of the
primary xylem, x (fig. 175), is succeeded by a broad band of parenchyma
(the meristematic zone), m, and beyond this are remnants of the secretory
zone, s. The structure of the leaf-traces corresponds with that of other
specimens of the type, but the much steeper course of these vascular
strands, lt, lt′ (fig. 176), is a feature in which this example differs from most
of those referred to L. fuliginosum. Such evidence as is available would
seem to point to the absence of trustworthy criteria enabling us to separate,
on anatomical grounds, Lepidophloios and Lepidodendron[334].
the “species” L. obovatum includes at least two widely different species.
This merely emphasizes the importance of correlating structure and external
characters as far as available data permit.
Fig. 176. Lepidodendron aculeatum. (Cambridge Botany School.)
The specimen, of which part of the surface is shown in fig. 174, is in all
probability L. aculeatum Sternb. This was described by me in detail in The
Annals of Botany (1906) as another example of the co-existence of the
Lepidodendron fuliginosum type of anatomy with a true Lepidodendron.
The locality of the specimen is not known. The leaf-cushions are 1·5 cm.
long with tapered upper and lower ends; a ligular cavity may be recognised
on some parts of the fossil, also faint indications of leaf-trace scars. The
tubercles (fig. 174, A–C, t) probably represent leaf-traces which the
shrinkage of the superficial tissues has rendered visible in the lower part of
their course. The circular scar, s (fig. B), on the partially decorticated
surface is apparently a wound. The stele is sufficiently well preserved to
justify its reference to L. fuliginosum. The irregularly crenulated edge of the
primary xylem, x (fig. 175), is succeeded by a broad band of parenchyma
(the meristematic zone), m, and beyond this are remnants of the secretory
zone, s. The structure of the leaf-traces corresponds with that of other
specimens of the type, but the much steeper course of these vascular
strands, lt, lt′ (fig. 176), is a feature in which this example differs from most
of those referred to L. fuliginosum. Such evidence as is available would
seem to point to the absence of trustworthy criteria enabling us to separate,
on anatomical grounds, Lepidophloios and Lepidodendron[334].
Page 191
Fig. 177. Stigmaria radiculosa (Hick). (From sections in the Manchester University
Collection.)
Stigmaria radiculosa (Hick).
We have no proof of the nature of the subterranean organs of
Lepidodendron fuliginosum, though it is not improbable that the specimens
described below may be correctly assigned by Weiss to that species. Prof.
Weiss[335] has made an interesting contribution to our knowledge of a type
first described by Hick[336] under the name Tylophora radiculosa, a
designation which he afterwards altered to Xenophyton radiculosum[337] and
for which we may now substitute Stigmaria radiculosa (Hick). Prof.
Williamson expressed the opinion that Xenophyton exhibited considerable
affinity with Stigmaria ficoides and Weiss’s further study of the species
leads him to regard Hick’s plant as probably the Stigmarian organ of
Lepidodendron fuliginosum. The diagrammatic transverse section
represented in fig. 177, A (4·5 cm. in diameter), shows an outer cortex of
parenchyma, c3, consisting in part of radial rows of secondary tissue and of
a band of compact parenchyma bounded by the wavy line a; at sc is a series
of secretory strands exactly like those in a corresponding position in
Lepidodendron fuliginosum and other species of the genus. The greater part
of the organ is occupied by a lacunar and hyphal middle cortex identical in
Collection.)
Stigmaria radiculosa (Hick).
We have no proof of the nature of the subterranean organs of
Lepidodendron fuliginosum, though it is not improbable that the specimens
described below may be correctly assigned by Weiss to that species. Prof.
Weiss[335] has made an interesting contribution to our knowledge of a type
first described by Hick[336] under the name Tylophora radiculosa, a
designation which he afterwards altered to Xenophyton radiculosum[337] and
for which we may now substitute Stigmaria radiculosa (Hick). Prof.
Williamson expressed the opinion that Xenophyton exhibited considerable
affinity with Stigmaria ficoides and Weiss’s further study of the species
leads him to regard Hick’s plant as probably the Stigmarian organ of
Lepidodendron fuliginosum. The diagrammatic transverse section
represented in fig. 177, A (4·5 cm. in diameter), shows an outer cortex of
parenchyma, c3, consisting in part of radial rows of secondary tissue and of
a band of compact parenchyma bounded by the wavy line a; at sc is a series
of secretory strands exactly like those in a corresponding position in
Lepidodendron fuliginosum and other species of the genus. The greater part
of the organ is occupied by a lacunar and hyphal middle cortex identical in
Page 192
structure with that shown in fig. 178, B, drawn from a rootlet. At d, fig. 177,
A, the middle cortex has been invaded by a narrow tongue of outer cortical
tissue. The stele is characterised by a large pith filled with parenchyma; in
Stigmaria ficoides[338] the general absence of pith-tissue has led to the
inference that the stele was hollow. The xylem is represented by a ring of
bundles separated by broad medullary rays; each bundle contains a few
small, apparently primary, elements on its inner edge but is mainly
composed of radial rows of secondary tracheae x2, fig. 177, B. On the outer
face of the secondary xylem occur a few smaller and thinner walled cells, c,
having the appearance of meristematic tissue; from these additional
tracheae were added to the xylem. This meristematic zone occurs, as in the
stems of Lepidodendron, immediately internal to the secretory tissue, sc; at
c1, fig. 177, B, is seen the inner cortical tissue.
Fig. 178. Rootlet of Stigmaria. (From a section in the Manchester Collection.)
A, the middle cortex has been invaded by a narrow tongue of outer cortical
tissue. The stele is characterised by a large pith filled with parenchyma; in
Stigmaria ficoides[338] the general absence of pith-tissue has led to the
inference that the stele was hollow. The xylem is represented by a ring of
bundles separated by broad medullary rays; each bundle contains a few
small, apparently primary, elements on its inner edge but is mainly
composed of radial rows of secondary tracheae x2, fig. 177, B. On the outer
face of the secondary xylem occur a few smaller and thinner walled cells, c,
having the appearance of meristematic tissue; from these additional
tracheae were added to the xylem. This meristematic zone occurs, as in the
stems of Lepidodendron, immediately internal to the secretory tissue, sc; at
c1, fig. 177, B, is seen the inner cortical tissue.
Fig. 178. Rootlet of Stigmaria. (From a section in the Manchester Collection.)
Page 193
In surface-view a specimen figured by Hick[339] shows a number of
circular scars agreeing in shape and arrangement with the rootlet scars of
Stigmaria ficoides. At b in fig. 177, A, the basal portion of a rootlet is
shown in organic connexion with the outer cortex. The rootlet-bundles are
given off from the stele as in other examples of Stigmaria; each bundle
consists of a triangular strand of xylem with an endarch protoxylem at the
narrow end accompanied by a portion of the secretory tissue as in the leaf-
traces. As in Stigmaria ficoides the rootlets are attached to the outer cortex
above a cushion of small cells. It is interesting to find that rootlet-bundles,
as seen in tangential section of the main axis, are associated with a
parichnos strand, but this is on the xylem side of the vascular strand,
whereas in the case of leaf-traces the parichnos is on the other side of the
bundle.
Fig. 178, A, represents a transverse section of a rootlet (6 mm. in
diameter) associated with Stigmaria radiculosa and probably belonging to
this species. The xylem strand x is composed of a group of tracheae with a
single protoxylem strand, px, at the pointed end and with small metaxylem
elements at the broad end next the space originally occupied by the so-
called phloem. A parenchymatous sheath, c′, surrounds the bundle, and
beyond this is the broad middle cortex, a small portion of which is shown
on a larger scale in fig. 178, B; as Weiss points out, some of the outermost
cells of the lacunar cortex (m) are clearly in a state of meristematic activity.
The preservation of the middle cortex and the small quantity of
secondary xylem are characters which this Stigmaria shares with
Lepidodendron fuliginosum, and although decisive evidence is still to seek,
we may express the opinion that Weiss’s surmise of a connexion between
Stigmaria radiculosa and Lepidodendron fuliginosum is probably correct.
5. Lepidodendron Harcourtii. Fig. 179, A–D.
In 1831 Mr Witham[340] published an anatomical description of a fragment
of a Lepidodendron which he named Lepidodendron Harcourtii after Mr C.
G. V. Vernon Harcourt from whom the specimen was originally obtained.
The fossil was found in rocks belonging to the Calciferous series in
Northumberland. Witham reproduced the account of this species in his
classic work on Fossil Vegetables[341], and Lindley and Hutton[342], who
examined Mr Harcourt’s material, published a description of it in their
circular scars agreeing in shape and arrangement with the rootlet scars of
Stigmaria ficoides. At b in fig. 177, A, the basal portion of a rootlet is
shown in organic connexion with the outer cortex. The rootlet-bundles are
given off from the stele as in other examples of Stigmaria; each bundle
consists of a triangular strand of xylem with an endarch protoxylem at the
narrow end accompanied by a portion of the secretory tissue as in the leaf-
traces. As in Stigmaria ficoides the rootlets are attached to the outer cortex
above a cushion of small cells. It is interesting to find that rootlet-bundles,
as seen in tangential section of the main axis, are associated with a
parichnos strand, but this is on the xylem side of the vascular strand,
whereas in the case of leaf-traces the parichnos is on the other side of the
bundle.
Fig. 178, A, represents a transverse section of a rootlet (6 mm. in
diameter) associated with Stigmaria radiculosa and probably belonging to
this species. The xylem strand x is composed of a group of tracheae with a
single protoxylem strand, px, at the pointed end and with small metaxylem
elements at the broad end next the space originally occupied by the so-
called phloem. A parenchymatous sheath, c′, surrounds the bundle, and
beyond this is the broad middle cortex, a small portion of which is shown
on a larger scale in fig. 178, B; as Weiss points out, some of the outermost
cells of the lacunar cortex (m) are clearly in a state of meristematic activity.
The preservation of the middle cortex and the small quantity of
secondary xylem are characters which this Stigmaria shares with
Lepidodendron fuliginosum, and although decisive evidence is still to seek,
we may express the opinion that Weiss’s surmise of a connexion between
Stigmaria radiculosa and Lepidodendron fuliginosum is probably correct.
5. Lepidodendron Harcourtii. Fig. 179, A–D.
In 1831 Mr Witham[340] published an anatomical description of a fragment
of a Lepidodendron which he named Lepidodendron Harcourtii after Mr C.
G. V. Vernon Harcourt from whom the specimen was originally obtained.
The fossil was found in rocks belonging to the Calciferous series in
Northumberland. Witham reproduced the account of this species in his
classic work on Fossil Vegetables[341], and Lindley and Hutton[342], who
examined Mr Harcourt’s material, published a description of it in their
Page 194
Fossil Flora in which they expressed the view that Lepidodendron is
intermediate between Conifers and Lycopods. Adolphe Brongniart[343]
included in his memoir on Sigillaria elegans an account of Witham’s
species based on material presented to the Paris Museum by Mr Hutton and
Robert Brown. Dr Kidston[344] has shown that the actual transverse section
figured by Witham is now in the York Museum; a piece of stem in the same
Museum, which is not the specimen from which Witham’s section was cut,
supplied the transverse section figured by Brongniart. The figures given by
Lindley and Hutton do not appear to have been made from the York
specimens. In 1887 Williamson[345] published a note in which he pointed out
that some of the specimens described by him as L. Harcourtii should be
transferred to a distinct species, which he named L. fuliginosum.
Subsequently in 1893 he gave a fuller account of Witham’s species; it has,
however, been shown by Dr Kidston and by Mr Watson[346] that certain
specimens identified by Williamson as L. Harcourtii differ sufficiently from
that type to be placed in another species, for which Watson proposes the
name L. Hickii.
A paper on L. Harcourtii published by Bertrand[347] in 1891 extends our
knowledge of this type in regard to several anatomical details. It was
recognised by Williamson that the absence of secondary wood in shoots
possessing the anatomical characters of L. Harcourtii is a feature to which
no great importance should be attached. It is possible that the large stems
from the Isle of Arran described by Williamson[348] as Lepidodendron
Wünschianum, in which the secondary wood is well developed, may be
specifically identical with the smaller specimens from Northumberland and
elsewhere which are recognised as examples of Witham’s type.
The diagrammatic sketch shown in fig. 179, A, was made from a section
figured by Williamson in 1893[349]; it has a diameter of 9 × 8·5 cm. The stele
is of the medullated type like that of L. Wünschianum, and the outer edge of
the primary xylem is characterised by sharp and prominent projecting
ridges similar to those of L. fuliginosum but rather more prominent.
Parenchymatous cells succeed the xylem, as in other species, but in this
case there is no indication of meristematic activity; beyond this region
occur occasional patches of a partially destroyed secretory zone. Remains
of a lacunar tissue are seen in the middle cortical region; also numerous
leaf-traces, lt, consisting of a tangentially elongated xylem strand
intermediate between Conifers and Lycopods. Adolphe Brongniart[343]
included in his memoir on Sigillaria elegans an account of Witham’s
species based on material presented to the Paris Museum by Mr Hutton and
Robert Brown. Dr Kidston[344] has shown that the actual transverse section
figured by Witham is now in the York Museum; a piece of stem in the same
Museum, which is not the specimen from which Witham’s section was cut,
supplied the transverse section figured by Brongniart. The figures given by
Lindley and Hutton do not appear to have been made from the York
specimens. In 1887 Williamson[345] published a note in which he pointed out
that some of the specimens described by him as L. Harcourtii should be
transferred to a distinct species, which he named L. fuliginosum.
Subsequently in 1893 he gave a fuller account of Witham’s species; it has,
however, been shown by Dr Kidston and by Mr Watson[346] that certain
specimens identified by Williamson as L. Harcourtii differ sufficiently from
that type to be placed in another species, for which Watson proposes the
name L. Hickii.
A paper on L. Harcourtii published by Bertrand[347] in 1891 extends our
knowledge of this type in regard to several anatomical details. It was
recognised by Williamson that the absence of secondary wood in shoots
possessing the anatomical characters of L. Harcourtii is a feature to which
no great importance should be attached. It is possible that the large stems
from the Isle of Arran described by Williamson[348] as Lepidodendron
Wünschianum, in which the secondary wood is well developed, may be
specifically identical with the smaller specimens from Northumberland and
elsewhere which are recognised as examples of Witham’s type.
The diagrammatic sketch shown in fig. 179, A, was made from a section
figured by Williamson in 1893[349]; it has a diameter of 9 × 8·5 cm. The stele
is of the medullated type like that of L. Wünschianum, and the outer edge of
the primary xylem is characterised by sharp and prominent projecting
ridges similar to those of L. fuliginosum but rather more prominent.
Parenchymatous cells succeed the xylem, as in other species, but in this
case there is no indication of meristematic activity; beyond this region
occur occasional patches of a partially destroyed secretory zone. Remains
of a lacunar tissue are seen in the middle cortical region; also numerous
leaf-traces, lt, consisting of a tangentially elongated xylem strand
Page 195
accompanied by a strand of secretory zone tissue enclosed in a sheath of
delicate parenchyma. In the inner part of the outer cortex, c3, the leaf-traces
lie in a space originally occupied by the parichnos; in the outer portion of
the same region a band of secondary cortex, pd, has been formed;
immediately internal to this occur numerous patches of secretory tissue,
represented by small dots in the drawing close to pd; one is shown on a
larger scale in fig. B.
The position of the phellogen is seen at a; external to this are radial rows
of rather large cells with dark contents.
Fig. 179.
A–D. Lepidodendron Harcourtii, Witham.
E. Lepidodendron fuliginosum, Shore, Lancashire.
A, B. From a specimen in the Williamson Collection, British Museum (No. 380), from
Airdrie, Scotland.
C, D. From sections in the Collection of Dr Kidston, from Shore, Lancashire.
delicate parenchyma. In the inner part of the outer cortex, c3, the leaf-traces
lie in a space originally occupied by the parichnos; in the outer portion of
the same region a band of secondary cortex, pd, has been formed;
immediately internal to this occur numerous patches of secretory tissue,
represented by small dots in the drawing close to pd; one is shown on a
larger scale in fig. B.
The position of the phellogen is seen at a; external to this are radial rows
of rather large cells with dark contents.
Fig. 179.
A–D. Lepidodendron Harcourtii, Witham.
E. Lepidodendron fuliginosum, Shore, Lancashire.
A, B. From a specimen in the Williamson Collection, British Museum (No. 380), from
Airdrie, Scotland.
C, D. From sections in the Collection of Dr Kidston, from Shore, Lancashire.
Page 196
Fig. 179, C, x, shows the characteristic form of the primary xylem edge,
beyond which are seen oval or circular leaf-traces with a mesarch
protoxylem, lt, px. It is possible that this specimen may not be specifically
identical with Witham’s species, but it represents a very similar if not
identical type; it may on the other hand be referable to L. fuliginosum. The
importance of the specimen, apart from its precise specific position, is that
it serves to illustrate the general appearance of the xylem surface met with
in both species, L. Harcourtii and L. fuliginosum. A tangential longitudinal
section, taken through the line ab in fig. C, is represented in fig. 179, D.
The xylem of the leaf-traces lt, consisting chiefly of scalariform tracheae,
alternates with patches of crushed and delicate parenchyma which
immediately abut on the primary xylem; at p, p, the section passes through
some of the projecting arms of the xylem cylinder; at m is seen a patch of
meristematic zone tissue. This section together with the similar section of
Lepidodendron vasculare described on a previous page demonstrates that
the projecting ridges of the primary xylem form apparently vertical bands:
they are not characterised by a lattice-work arrangement as described by
Bertrand and by other authors who have accepted his conclusions. If a
reticulum of intersecting ridges were present on the face of the xylem
cylinder its existence would be revealed by such a section as that
represented in fig. 179, D.
beyond which are seen oval or circular leaf-traces with a mesarch
protoxylem, lt, px. It is possible that this specimen may not be specifically
identical with Witham’s species, but it represents a very similar if not
identical type; it may on the other hand be referable to L. fuliginosum. The
importance of the specimen, apart from its precise specific position, is that
it serves to illustrate the general appearance of the xylem surface met with
in both species, L. Harcourtii and L. fuliginosum. A tangential longitudinal
section, taken through the line ab in fig. C, is represented in fig. 179, D.
The xylem of the leaf-traces lt, consisting chiefly of scalariform tracheae,
alternates with patches of crushed and delicate parenchyma which
immediately abut on the primary xylem; at p, p, the section passes through
some of the projecting arms of the xylem cylinder; at m is seen a patch of
meristematic zone tissue. This section together with the similar section of
Lepidodendron vasculare described on a previous page demonstrates that
the projecting ridges of the primary xylem form apparently vertical bands:
they are not characterised by a lattice-work arrangement as described by
Bertrand and by other authors who have accepted his conclusions. If a
reticulum of intersecting ridges were present on the face of the xylem
cylinder its existence would be revealed by such a section as that
represented in fig. 179, D.
Page 197
Fig. 180. Lepidodendron Wünschianum. From Arran. (⅕ nat. size.) (Sedgwick Museum,
Cambridge.)
6. Lepidodendron Wünschianum (Williamson). Figs. 180–184.
Reference was made in Volume I. to the occurrence of large stems of a
Lepidodendron in volcanic beds of Calciferous sandstone age in the island
of Arran[350]. These were discovered and briefly described by Mr Wünsch in
1867[351] and afterwards named by Carruthers Lomatophloyos
Wünschianus[352]. Mr Carruthers visited the locality and published an
account of the peculiar method of preservation of the plant remains[353]. It is,
however, to Williamson[354] that we owe the more complete description of
these Arran stems. Portions of large stems from the Arran beds are
preserved in the British Museum, the Sedgwick Museum, Cambridge, and
in the Manchester Museum. The section of one of these is shown in fig.
180; an outer shell of bark encloses a mass of volcanic ash in which are
embedded several woody cylinders originally described as “internal
piths[355],” and by Carruthers as young stems produced from spores which
had germinated in the hollow trunk of a large tree. The true interpretation
was supplied by Williamson who showed that a stem of the dimensions of
that represented by the outer cortex, e, fig. 180, must have possessed a
single stele of the size of those seen in the interior of the hollow trunk. The
Cambridge.)
6. Lepidodendron Wünschianum (Williamson). Figs. 180–184.
Reference was made in Volume I. to the occurrence of large stems of a
Lepidodendron in volcanic beds of Calciferous sandstone age in the island
of Arran[350]. These were discovered and briefly described by Mr Wünsch in
1867[351] and afterwards named by Carruthers Lomatophloyos
Wünschianus[352]. Mr Carruthers visited the locality and published an
account of the peculiar method of preservation of the plant remains[353]. It is,
however, to Williamson[354] that we owe the more complete description of
these Arran stems. Portions of large stems from the Arran beds are
preserved in the British Museum, the Sedgwick Museum, Cambridge, and
in the Manchester Museum. The section of one of these is shown in fig.
180; an outer shell of bark encloses a mass of volcanic ash in which are
embedded several woody cylinders originally described as “internal
piths[355],” and by Carruthers as young stems produced from spores which
had germinated in the hollow trunk of a large tree. The true interpretation
was supplied by Williamson who showed that a stem of the dimensions of
that represented by the outer cortex, e, fig. 180, must have possessed a
single stele of the size of those seen in the interior of the hollow trunk. The
Page 198
additional woody cylinders, or steles, were derived from other stems, and
carried, probably by water, into the partially decayed trunk. In addition to
large Lepidodendron stems Williamson described smaller shoots as well as
an Halonial branch and made brief reference to some cones described by
Binney[356] in 1871 from the same locality.
The following account of Lepidodendron Wünschianum is based on an
exceptionally fine specimen discovered by Mr T. Kerr of Edinburgh in
Calciferous sandstone volcanic ashes at Dalmeny in Linlithgowshire. The
material from this locality described by Mr Hill and myself[357] was
generously placed in my hands by Dr Kidston of Stirling. Fig. 181, A,
shows a transverse section, 33 cm. in diameter, consisting of a shell of outer
cortical tissue enclosing a core of light-coloured volcanic ash; on the decay
of the more delicate middle cortex the cylindrical stele dropped to one side
of the hollow trunk. The stele, fig. 182, has a diameter of 6·5 cm.; the centre
is occupied by concentric layers of silica, s, surrounded externally by the
remains of a parenchymatous pith, p, made up of isodiametric and sinuous
hypha-like elements like those in the middle cortex of Lepidodendron
shoots. On the inner edge of the primary xylem, x′, occur several
isodiametric tracheae with fine scalariform and reticulate thickening bands
like those in the central region of the stele of Lepidodendron vasculare: it is
probable that these elements are vestiges of conducting tissue which in
ancestral forms formed a solid and not a medullated stele.
carried, probably by water, into the partially decayed trunk. In addition to
large Lepidodendron stems Williamson described smaller shoots as well as
an Halonial branch and made brief reference to some cones described by
Binney[356] in 1871 from the same locality.
The following account of Lepidodendron Wünschianum is based on an
exceptionally fine specimen discovered by Mr T. Kerr of Edinburgh in
Calciferous sandstone volcanic ashes at Dalmeny in Linlithgowshire. The
material from this locality described by Mr Hill and myself[357] was
generously placed in my hands by Dr Kidston of Stirling. Fig. 181, A,
shows a transverse section, 33 cm. in diameter, consisting of a shell of outer
cortical tissue enclosing a core of light-coloured volcanic ash; on the decay
of the more delicate middle cortex the cylindrical stele dropped to one side
of the hollow trunk. The stele, fig. 182, has a diameter of 6·5 cm.; the centre
is occupied by concentric layers of silica, s, surrounded externally by the
remains of a parenchymatous pith, p, made up of isodiametric and sinuous
hypha-like elements like those in the middle cortex of Lepidodendron
shoots. On the inner edge of the primary xylem, x′, occur several
isodiametric tracheae with fine scalariform and reticulate thickening bands
like those in the central region of the stele of Lepidodendron vasculare: it is
probable that these elements are vestiges of conducting tissue which in
ancestral forms formed a solid and not a medullated stele.
Page 199
Fig. 181. Lepidodendron Wünschianum. Calciferous Sandstone, Dalmeny. (A, Sedgwick
Museum, Cambridge. B–F, Botany School, Cambridge.)
Museum, Cambridge. B–F, Botany School, Cambridge.)
Page 200
Fig. 182. Lepidodendron Wünschianum. The stele of the stem shown in fig. 181, A.
(Cambridge Botany School.)
The primary xylem is limited externally by an unequally fluted surface
with exarch protoxylem elements; it is, however, noteworthy that there is
not always a very clearly defined difference between the small protoxylem
and the large centripetally developed tracheae. Immediately beyond the
primary xylem occur numerous thin-walled parenchymatous cells with
spiral and reticulate pitting; beyond these is the broad zone of secondary
xylem, x2, composed of scalariform tracheae and numerous medullary rays
consisting of one, two, or several rows of radially elongated elements with
(Cambridge Botany School.)
The primary xylem is limited externally by an unequally fluted surface
with exarch protoxylem elements; it is, however, noteworthy that there is
not always a very clearly defined difference between the small protoxylem
and the large centripetally developed tracheae. Immediately beyond the
primary xylem occur numerous thin-walled parenchymatous cells with
spiral and reticulate pitting; beyond these is the broad zone of secondary
xylem, x2, composed of scalariform tracheae and numerous medullary rays
consisting of one, two, or several rows of radially elongated elements with
Page 201
spiral and reticulate pitting. In tangential sections the rays are seen to vary
considerably in size, some being made up of a single row of cells while
others are longer and broader; through the latter leaf-traces pass
horizontally. Portions of medullary rays are seen at mr in fig. 181, C and E.
The leaf-traces given off from projecting ridges on the outer edge of the
primary xylem pass upwards for a short distance and then bend outwards
through a broad medullary ray; on reaching the limit of the secondary
xylem they again bend sharply upwards, appearing in transverse section at
lt fig. 181, B. Each leaf-trace consists at first of long tracheae accompanied
by numerous thin-walled spiral and reticulate parenchymatous cells derived
from the tissue in contact with the outer edge of the primary wood. Fig.
181, B, shows a leaf-trace near the edge of the secondary xylem; it consists
of a group of primary tracheae, with narrower protoxylem elements, px,
near the outer margin, almost completely enclosed by radially disposed
series of smaller and more delicate tracheae. These secondary elements of
the leaf-trace are apparently added during its passage through the medullary
ray, but additions are also made to this tissue by the meristematic zone, m,
fig. 181, B and E. In contact with the outermost tracheae of normal size at
the edge of the secondary xylem there are some smaller lignified elements,
as at a, fig. 181, E, and at T, fig. 183; this juxtaposition of large and small
tracheae has been referred to in the description of L. vasculare.
Prof. Williamson[358], in his account of the Arran specimens of this
species, expressed the opinion that the trees probably perished “in
consequence of the mephitic vapours which filled the atmosphere”; it
maybe that in the striking difference in the diameter of the conducting
elements on the margin of the wood we have evidence of approaching
death.
Beyond the most recently formed tracheae we have a band of delicate
parenchymatous cells (m, figs. B and E, 181; C, figs. 183, 184) forming the
meristematic zone[359]. The longitudinal section represented in fig. 184
shows some recently formed narrow tracheae, T, and beyond these the
meristematic zone composed of thin-walled short cells, C, arranged in
horizontal rows. It is this small-celled tissue to which the name phloem has
been applied by some authors[360], a term which seems to me to be
misleading and inappropriate. In passing through this zone of dividing cells
the leaf-traces become surrounded by an arc of meristem from which
considerably in size, some being made up of a single row of cells while
others are longer and broader; through the latter leaf-traces pass
horizontally. Portions of medullary rays are seen at mr in fig. 181, C and E.
The leaf-traces given off from projecting ridges on the outer edge of the
primary xylem pass upwards for a short distance and then bend outwards
through a broad medullary ray; on reaching the limit of the secondary
xylem they again bend sharply upwards, appearing in transverse section at
lt fig. 181, B. Each leaf-trace consists at first of long tracheae accompanied
by numerous thin-walled spiral and reticulate parenchymatous cells derived
from the tissue in contact with the outer edge of the primary wood. Fig.
181, B, shows a leaf-trace near the edge of the secondary xylem; it consists
of a group of primary tracheae, with narrower protoxylem elements, px,
near the outer margin, almost completely enclosed by radially disposed
series of smaller and more delicate tracheae. These secondary elements of
the leaf-trace are apparently added during its passage through the medullary
ray, but additions are also made to this tissue by the meristematic zone, m,
fig. 181, B and E. In contact with the outermost tracheae of normal size at
the edge of the secondary xylem there are some smaller lignified elements,
as at a, fig. 181, E, and at T, fig. 183; this juxtaposition of large and small
tracheae has been referred to in the description of L. vasculare.
Prof. Williamson[358], in his account of the Arran specimens of this
species, expressed the opinion that the trees probably perished “in
consequence of the mephitic vapours which filled the atmosphere”; it
maybe that in the striking difference in the diameter of the conducting
elements on the margin of the wood we have evidence of approaching
death.
Beyond the most recently formed tracheae we have a band of delicate
parenchymatous cells (m, figs. B and E, 181; C, figs. 183, 184) forming the
meristematic zone[359]. The longitudinal section represented in fig. 184
shows some recently formed narrow tracheae, T, and beyond these the
meristematic zone composed of thin-walled short cells, C, arranged in
horizontal rows. It is this small-celled tissue to which the name phloem has
been applied by some authors[360], a term which seems to me to be
misleading and inappropriate. In passing through this zone of dividing cells
the leaf-traces become surrounded by an arc of meristem from which
Page 202
elements are added to the radially placed rows of secondary tracheae.
Beyond the meristematic region portions of the secretory zone are
preserved, consisting of large sacs or spaces and small dark cells as seen in
figs. 181, B, E, sc, F; 183, 184. This tissue has the same structure as in L.
vasculare and in L. fuliginosum: it is a striking fact that there are no
indications of any additions to the secretory zone even in stems with such a
large amount of secondary xylem as in the Dalmeny specimen (fig. 182, x2).
If the secretory zone were of the nature of phloem we should expect to see
signs of additions made to it in the course of growth. In this connexion it is
worth mentioning that in the recent fern Botrychium (Ophioglossaceae)
secondary xylem is formed in the stem, but apparently no additions are
made to the phloem. The structure of the secretory zone tissue as seen in the
longitudinal section fig. 184, S, is also a serious difficulty in the way of
accepting the designation phloem as employed by Scott and Weiss. Between
the secretory zone and the outer cortical region, no tissues have been
preserved. The shell of bark consists chiefly of radial rows of elongated
cells with rather thick walls characterised by the occurrence of small
intercellular spaces and by tangentially placed bands of secretory cells and
sacs (fig. 181, D, s). Immediately internal to the secondary cortex or
phelloderm occur groups of secretory tissue as shown in the section of L.
Harcourtii (fig. 179, B).
Beyond the meristematic region portions of the secretory zone are
preserved, consisting of large sacs or spaces and small dark cells as seen in
figs. 181, B, E, sc, F; 183, 184. This tissue has the same structure as in L.
vasculare and in L. fuliginosum: it is a striking fact that there are no
indications of any additions to the secretory zone even in stems with such a
large amount of secondary xylem as in the Dalmeny specimen (fig. 182, x2).
If the secretory zone were of the nature of phloem we should expect to see
signs of additions made to it in the course of growth. In this connexion it is
worth mentioning that in the recent fern Botrychium (Ophioglossaceae)
secondary xylem is formed in the stem, but apparently no additions are
made to the phloem. The structure of the secretory zone tissue as seen in the
longitudinal section fig. 184, S, is also a serious difficulty in the way of
accepting the designation phloem as employed by Scott and Weiss. Between
the secretory zone and the outer cortical region, no tissues have been
preserved. The shell of bark consists chiefly of radial rows of elongated
cells with rather thick walls characterised by the occurrence of small
intercellular spaces and by tangentially placed bands of secretory cells and
sacs (fig. 181, D, s). Immediately internal to the secondary cortex or
phelloderm occur groups of secretory tissue as shown in the section of L.
Harcourtii (fig. 179, B).
Page 203
Fig. 183. Lepidodendron Wünschianum. From the specimen shown in fig. 181, S, secretory
zone; C, meristem; T, immature tracheae.
zone; C, meristem; T, immature tracheae.
Page 204
Fig. 184. Lepidodendron Wünschianum. Longitudinal section of the specimen represented in
transverse section in fig. 183.
The large tree shown in transverse section in fig. 181, A, has lost its leaf-
cushions; the bark, as seen in the lower part of the photograph, presents a
fissured appearance like that with which we are familiar on an old Oak or
Elm stem. A radial longitudinal section through the phelloderm revealed the
existence of a crushed leaf-trace passing outwards in an approximately
horizontal course accompanied by a strand of parenchymatous tissue[361]
having the characteristic structure of a parichnos. It is probable that the
surface of this partially decorticated stem differed in appearance from that
transverse section in fig. 183.
The large tree shown in transverse section in fig. 181, A, has lost its leaf-
cushions; the bark, as seen in the lower part of the photograph, presents a
fissured appearance like that with which we are familiar on an old Oak or
Elm stem. A radial longitudinal section through the phelloderm revealed the
existence of a crushed leaf-trace passing outwards in an approximately
horizontal course accompanied by a strand of parenchymatous tissue[361]
having the characteristic structure of a parichnos. It is probable that the
surface of this partially decorticated stem differed in appearance from that
Page 205
of an old Sigillaria (cf. fig. 198) in the much smaller and less conspicuous
parichnos strands.
In addition to the large stems of L. Wünschianum from Arran and
Dalmeny numerous examples of smaller axes from the former locality are
represented in the Williamson collection (British Museum). Some of the
twigs are characterised by a solid stele (protostele) giving off numerous
leaf-traces accompanied by short spirally thickened tracheids like those
which occur at the outer edge of the primary xylem in the larger stem: these
extend into the leaf where they are arranged round the vascular bundle like
the transfusion tracheids[362] in many recent conifers. The surface of these
smaller shoots bears large leaf-cushions which are seen in longitudinal
section to have the form characteristic of Lepidophloios. It is worthy of note
that a section of a bifurcating axis of this species from the Calciferous
Sandstone of Craigleith (British Museum Collection[363]), although its
diameter is 19 × 14 cm., shows no signs of secondary wood. This late
appearance of secondary xylem and other anatomical features suggest the
possibility of the specific identity of L. Wünschianum and L. Harcourtii[364].
In 1871 Binney[365] described a specimen of a heterosporous cone,
Lepidostrobus Wünschianus, from Arran exhibiting the ordinary features of
lepidodendroid strobili; this was probably borne by Lepidodendron
Wünschianum.
7. Lepidodendron macrophyllum (Williamson). Fig. 186, C.
The diagrammatic sketch reproduced in fig. 186, C, was made from the
transverse section of a small twig, slightly less than 2 cm. in its longest
diameter, originally figured by Williamson[366] in 1872. Earlier in the same
year Carruthers[367] published a short account of the same form based on
specimens collected by Mr Butterworth from the Coal-Measures of
Lancashire near Oldham, but both authors refrained from instituting a new
specific name. In a later publication Williamson spoke of the type as
Lepidodendron macrophyllum[368]. Williamson’s species has nothing to do
with Lycopodites macrophyllus of Goldenberg[369]. The most striking feature
of this rare form is the large size of the leaf-cushions, which are of the
Lepidophloios type, in proportion to the diameter of the shoot. The stele
consists of a ring of xylem, all of which is primary in the sections so far
parichnos strands.
In addition to the large stems of L. Wünschianum from Arran and
Dalmeny numerous examples of smaller axes from the former locality are
represented in the Williamson collection (British Museum). Some of the
twigs are characterised by a solid stele (protostele) giving off numerous
leaf-traces accompanied by short spirally thickened tracheids like those
which occur at the outer edge of the primary xylem in the larger stem: these
extend into the leaf where they are arranged round the vascular bundle like
the transfusion tracheids[362] in many recent conifers. The surface of these
smaller shoots bears large leaf-cushions which are seen in longitudinal
section to have the form characteristic of Lepidophloios. It is worthy of note
that a section of a bifurcating axis of this species from the Calciferous
Sandstone of Craigleith (British Museum Collection[363]), although its
diameter is 19 × 14 cm., shows no signs of secondary wood. This late
appearance of secondary xylem and other anatomical features suggest the
possibility of the specific identity of L. Wünschianum and L. Harcourtii[364].
In 1871 Binney[365] described a specimen of a heterosporous cone,
Lepidostrobus Wünschianus, from Arran exhibiting the ordinary features of
lepidodendroid strobili; this was probably borne by Lepidodendron
Wünschianum.
7. Lepidodendron macrophyllum (Williamson). Fig. 186, C.
The diagrammatic sketch reproduced in fig. 186, C, was made from the
transverse section of a small twig, slightly less than 2 cm. in its longest
diameter, originally figured by Williamson[366] in 1872. Earlier in the same
year Carruthers[367] published a short account of the same form based on
specimens collected by Mr Butterworth from the Coal-Measures of
Lancashire near Oldham, but both authors refrained from instituting a new
specific name. In a later publication Williamson spoke of the type as
Lepidodendron macrophyllum[368]. Williamson’s species has nothing to do
with Lycopodites macrophyllus of Goldenberg[369]. The most striking feature
of this rare form is the large size of the leaf-cushions, which are of the
Lepidophloios type, in proportion to the diameter of the shoot. The stele
consists of a ring of xylem, all of which is primary in the sections so far
Page 206
described, enclosing a parenchymatous pith: a Stigmarian rootlet is shown
at s.
8. Lepidodendron Veltheimianum Sternb. (General account). Figs. 157,
185, 186, A, B.
1820. “Schuppenpflanze,” Rhode, Beit. zur Pflanzenkunde der
Vorwelt, Pl. iii. fig. 1.
1825. Lepidodendron Veltheimianum, Sternberg, Flora der Vorwelt,
Pl. lii. fig. 5.
1836. Pachyphloeus tetragonus, Goeppert, Die fossilen Farnkräuter,
Pl. xliii. fig. 5.
1852. Sagenaria Veltheimiana, Goeppert, Foss. Flora des
Übergangsgebirges, Pls. xvii–xxiv.
1875. Lepidodendron Veltheimianum, Stur, Culm Flora, p. 269, Pls.
xviii–xxii.
1886. Lepidodendron Veltheimianum, Kidston, Catalogue of
Palaeozoic plants, British Museum, p. 160.
1901. Lepidodendron Veltheimianum, Potonié, Silur und Culm
Flora, p. 116, figs. 72–76.
1904. Lepidodendron Veltheimianum, Zalessky, Mém. Com. Géol.
Russie, Pl. iv. figs. 4, 5.
1906. Lepidodendron Veltheimi, Potonié, Königl. Preuss. geol.
Landesanstalt, Lief. iii.
The above list may serve to call attention to a few synonyms[370] of this
plant, and to a selection of sources from which full information may be
obtained as to the history of our knowledge of this characteristic and widely
spread Lower Carboniferous type.
Lepidodendron Veltheimianum is represented by casts of stems, the
largest of which hitherto described reaches a length of 5·22 metres with a
maximum diameter of 63 cm.; this specimen, figured by Stur[371], consists of
a tapered main axis giving off smaller lateral shoots, some of which exhibit
dichotomous branching. Fig. 185, C and D, represent the external features
of a well-preserved cast and impression respectively. Oblique rows of
prominent cushions wind round the surface of the stem and branches: each
cushion is prolonged upwards and downwards in the form of a narrow ridge
at s.
8. Lepidodendron Veltheimianum Sternb. (General account). Figs. 157,
185, 186, A, B.
1820. “Schuppenpflanze,” Rhode, Beit. zur Pflanzenkunde der
Vorwelt, Pl. iii. fig. 1.
1825. Lepidodendron Veltheimianum, Sternberg, Flora der Vorwelt,
Pl. lii. fig. 5.
1836. Pachyphloeus tetragonus, Goeppert, Die fossilen Farnkräuter,
Pl. xliii. fig. 5.
1852. Sagenaria Veltheimiana, Goeppert, Foss. Flora des
Übergangsgebirges, Pls. xvii–xxiv.
1875. Lepidodendron Veltheimianum, Stur, Culm Flora, p. 269, Pls.
xviii–xxii.
1886. Lepidodendron Veltheimianum, Kidston, Catalogue of
Palaeozoic plants, British Museum, p. 160.
1901. Lepidodendron Veltheimianum, Potonié, Silur und Culm
Flora, p. 116, figs. 72–76.
1904. Lepidodendron Veltheimianum, Zalessky, Mém. Com. Géol.
Russie, Pl. iv. figs. 4, 5.
1906. Lepidodendron Veltheimi, Potonié, Königl. Preuss. geol.
Landesanstalt, Lief. iii.
The above list may serve to call attention to a few synonyms[370] of this
plant, and to a selection of sources from which full information may be
obtained as to the history of our knowledge of this characteristic and widely
spread Lower Carboniferous type.
Lepidodendron Veltheimianum is represented by casts of stems, the
largest of which hitherto described reaches a length of 5·22 metres with a
maximum diameter of 63 cm.; this specimen, figured by Stur[371], consists of
a tapered main axis giving off smaller lateral shoots, some of which exhibit
dichotomous branching. Fig. 185, C and D, represent the external features
of a well-preserved cast and impression respectively. Oblique rows of
prominent cushions wind round the surface of the stem and branches: each
cushion is prolonged upwards and downwards in the form of a narrow ridge
Page 207
with sloping sides which connects adjacent cushions by an ogee curve. At
the upper limit of the broader kite-shaped portion of the cushion the ligular
pit forms a conspicuous feature; immediately below this is the leaf-scar
with its three small scars,—the lateral parichnos strands and the central
leaf-trace. The two oval areas shown in fig. 185, D, just below the lower
edge of the leaf-scars, represent the parichnos arms which impinge on the
surface of the cushions on their way to the leaves, as explained on a
previous page. It is possible that these areas were visible on the living stem
as strands of loose parenchyma comparable with the lenticel-like pits on the
stipules of Angiopteris[372] and the leaf-bases of Cyatheaceous ferns, or it
may be that their prominence in the specimen before us is the result of the
decay of a thin layer of superficial cortex which hid them on the living tree.
Fig. 185, B, illustrates the appearance of a stem in a partially decorticated
condition (Bergeria state). A further degree of decortication is seen in fig.
185, A, which represents the Knorria condition.
Fig. 185. Lepidodendron Veltheimianum. From specimens in Dr Kidston’s Collection.
(Approximately nat. size.)
Fig. 157 shows a Ulodendron axis of this species; in the lower part the
specimen illustrates the partial obliteration of the surface features as the
the upper limit of the broader kite-shaped portion of the cushion the ligular
pit forms a conspicuous feature; immediately below this is the leaf-scar
with its three small scars,—the lateral parichnos strands and the central
leaf-trace. The two oval areas shown in fig. 185, D, just below the lower
edge of the leaf-scars, represent the parichnos arms which impinge on the
surface of the cushions on their way to the leaves, as explained on a
previous page. It is possible that these areas were visible on the living stem
as strands of loose parenchyma comparable with the lenticel-like pits on the
stipules of Angiopteris[372] and the leaf-bases of Cyatheaceous ferns, or it
may be that their prominence in the specimen before us is the result of the
decay of a thin layer of superficial cortex which hid them on the living tree.
Fig. 185, B, illustrates the appearance of a stem in a partially decorticated
condition (Bergeria state). A further degree of decortication is seen in fig.
185, A, which represents the Knorria condition.
Fig. 185. Lepidodendron Veltheimianum. From specimens in Dr Kidston’s Collection.
(Approximately nat. size.)
Fig. 157 shows a Ulodendron axis of this species; in the lower part the
specimen illustrates the partial obliteration of the surface features as the
Page 208
result of the splitting of the outer bark consequent on growth in thickness of
the tree. By an extension of the cracks, shown in an early stage in fig. 157,
the leaf-cushions would be entirely destroyed and the surface of the bark
would be characterised by longitudinal fissures simulating the vertical
grooves and ridges of a Sigillarian stem. The large stumps of trees shown in
the frontispiece to Volume I. are probably, as Kidston[373] suggests, trunks of
L. Veltheimianum in which the leaf-cushions have been replaced by
irregular longitudinal fissures. In old stems of Sigillaria the enlarged
parichnos areas constitute a characteristic feature (p. 205), but it does not
follow that the absence of large parichnos scars is a distinguishing feature
of all Lepidodendra.
In this species, as in others, the form of the leaf-cushion exhibits a
considerable range of variation dependent on the thickness of the shoot; the
contiguous cushions of young branches become stretched apart as the result
of increasing girth of the whole organ, and casts of still older branches may
exhibit very different surface-features[374]. The leaves as seen on
impressions of slender branches are comparatively short, reaching a length
of 1–2 cm. It is important to notice that leafy twigs of this species may bear
terminal cones[375] resembling in form those of Picea excelsa and other
recent conifers, though differing essentially in their morphological features.
The fossil stumps of trees represented in the frontispiece to Volume I.
bear horizontally spreading and dichotomously branched root-like organs
having the characters of Stigmaria ficoides[376]. Geinitz has suggested that
Stigmaria inaequalis Göpp. may be the underground portion of
Lepidodendron Veltheimianum.
It is unfortunately seldom possible to connect petrified Lepidodendron
cones with particular species of the genus based on purely vegetative
characters, but it is practically certain that we are justified in recognising
certain strobili described by Williamson[377] from the Calciferous Sandstone
series of Burntisland on the Firth of Forth as those of Lepidodendron
Veltheimianum. Williamson believed that the cone which he described
belonged to the plant with shoots characterised by the anatomical features
of his species Lepidodendron brevifolium (= L. Veltheimianum), a
conclusion which is confirmed by Kidston[378]. The cone of L.
Veltheimianum, which reached a diameter of at least 1 cm. and a length of 4
cm., agrees in essentials with other species of Lepidostrobus; the axis has a
the tree. By an extension of the cracks, shown in an early stage in fig. 157,
the leaf-cushions would be entirely destroyed and the surface of the bark
would be characterised by longitudinal fissures simulating the vertical
grooves and ridges of a Sigillarian stem. The large stumps of trees shown in
the frontispiece to Volume I. are probably, as Kidston[373] suggests, trunks of
L. Veltheimianum in which the leaf-cushions have been replaced by
irregular longitudinal fissures. In old stems of Sigillaria the enlarged
parichnos areas constitute a characteristic feature (p. 205), but it does not
follow that the absence of large parichnos scars is a distinguishing feature
of all Lepidodendra.
In this species, as in others, the form of the leaf-cushion exhibits a
considerable range of variation dependent on the thickness of the shoot; the
contiguous cushions of young branches become stretched apart as the result
of increasing girth of the whole organ, and casts of still older branches may
exhibit very different surface-features[374]. The leaves as seen on
impressions of slender branches are comparatively short, reaching a length
of 1–2 cm. It is important to notice that leafy twigs of this species may bear
terminal cones[375] resembling in form those of Picea excelsa and other
recent conifers, though differing essentially in their morphological features.
The fossil stumps of trees represented in the frontispiece to Volume I.
bear horizontally spreading and dichotomously branched root-like organs
having the characters of Stigmaria ficoides[376]. Geinitz has suggested that
Stigmaria inaequalis Göpp. may be the underground portion of
Lepidodendron Veltheimianum.
It is unfortunately seldom possible to connect petrified Lepidodendron
cones with particular species of the genus based on purely vegetative
characters, but it is practically certain that we are justified in recognising
certain strobili described by Williamson[377] from the Calciferous Sandstone
series of Burntisland on the Firth of Forth as those of Lepidodendron
Veltheimianum. Williamson believed that the cone which he described
belonged to the plant with shoots characterised by the anatomical features
of his species Lepidodendron brevifolium (= L. Veltheimianum), a
conclusion which is confirmed by Kidston[378]. The cone of L.
Veltheimianum, which reached a diameter of at least 1 cm. and a length of 4
cm., agrees in essentials with other species of Lepidostrobus; the axis has a
Page 209
single medullated stele of the same general type as that of the vegetative
shoots of Lepidodendron fuliginosum and L. Harcourtii. The sporophylls
are described by Williamson as spirally disposed, and Scott notices that in
some specimens they are arranged in alternate whorls; as in recent
Lycopods both forms of phyllotaxis may occur in the same species. The
heterosporous nature of this strobilus, to which Scott first applied the name
Lepidostrobus Veltheimianus, is clearly demonstrated by the two
longitudinal sections contributed by Mr Carruthers and figured by
Williamson in 1893[379].
Each sporophyll, attached almost at right angles to the cone-axis, bears a
radially elongated sporangium seated on the median line of its upper face;
its margins are laterally expanded as a thin lamina; from the middle of the
lower face a narrow keel extends downwards between two sporangia
belonging to a lower series. From the base of a sporangium a mass of sterile
tissue penetrates into the spore-producing region as in the large sporangia of
Isoetes (cf. fig. 191, H, a, and fig. 133, H). The distal and free portion of the
sporophylls is bent upwards as a protecting bract. Some of the sporangia in
the upper part of the cone produced numerous microspores, while 8–16
megaspores occur in the lower sporangia. The megaspores, having a mean
diameter of 0·8 mm. “quite 40 times the size of the microspores[380],” are
characterised by tubular capitate appendages, and by a conspicuous three-
lobed projection (fig. 191, E)[381] which, as Scott suggests, may represent the
outer spore-wall which has split as the result of germination. It is not
improbable, as shown in fig. 191, I, that this cap was present before
germination. The megaspores represented in fig. 191, I, illustrate their
characteristic form as seen in a section of a megasporangium, Sm; the open
beak-like portion of the larger spore is probably the apical region which has
split along the three-rayed lines. These lines form a characteristic feature of
both recent and extinct spores and denote their origin in tetrads. The spore
shown in fig. 191, E[382], illustrates the external features. The apical region
of the prothallus of a megaspore of Lepidodendron Veltheimianum
described by Mr Gordon[383] consists of smaller cells than those occupying
the greater part of the spore-cavity, a differentiation which he compares
with that of the prothallus of Selaginella.
shoots of Lepidodendron fuliginosum and L. Harcourtii. The sporophylls
are described by Williamson as spirally disposed, and Scott notices that in
some specimens they are arranged in alternate whorls; as in recent
Lycopods both forms of phyllotaxis may occur in the same species. The
heterosporous nature of this strobilus, to which Scott first applied the name
Lepidostrobus Veltheimianus, is clearly demonstrated by the two
longitudinal sections contributed by Mr Carruthers and figured by
Williamson in 1893[379].
Each sporophyll, attached almost at right angles to the cone-axis, bears a
radially elongated sporangium seated on the median line of its upper face;
its margins are laterally expanded as a thin lamina; from the middle of the
lower face a narrow keel extends downwards between two sporangia
belonging to a lower series. From the base of a sporangium a mass of sterile
tissue penetrates into the spore-producing region as in the large sporangia of
Isoetes (cf. fig. 191, H, a, and fig. 133, H). The distal and free portion of the
sporophylls is bent upwards as a protecting bract. Some of the sporangia in
the upper part of the cone produced numerous microspores, while 8–16
megaspores occur in the lower sporangia. The megaspores, having a mean
diameter of 0·8 mm. “quite 40 times the size of the microspores[380],” are
characterised by tubular capitate appendages, and by a conspicuous three-
lobed projection (fig. 191, E)[381] which, as Scott suggests, may represent the
outer spore-wall which has split as the result of germination. It is not
improbable, as shown in fig. 191, I, that this cap was present before
germination. The megaspores represented in fig. 191, I, illustrate their
characteristic form as seen in a section of a megasporangium, Sm; the open
beak-like portion of the larger spore is probably the apical region which has
split along the three-rayed lines. These lines form a characteristic feature of
both recent and extinct spores and denote their origin in tetrads. The spore
shown in fig. 191, E[382], illustrates the external features. The apical region
of the prothallus of a megaspore of Lepidodendron Veltheimianum
described by Mr Gordon[383] consists of smaller cells than those occupying
the greater part of the spore-cavity, a differentiation which he compares
with that of the prothallus of Selaginella.
Page 210
Fig. 186.
A, B. Lepidodendron Veltheimianum. (Botany School, Cambridge.)
C. Lepidodendron macrophyllum. (British Museum. No. 377.)
x, Primary xylem; x2, secondary xylem; s, Stigmarian rootlet.
There can be little doubt that the petrified shoots described by
Williamson[384] from the Calciferous Sandstone beds of Burntisland as
Lepidodendron brevifolium are identical with specimens possessing the
external features of L. Veltheimianum. In 1872 Dawson expressed the
opinion that Williamson’s species should be referred to L. Veltheimianum,
and evidence subsequently obtained confirms this view. The stele of this
species is of the medullated type, differing from that of L. fuliginosum and
L. Harcourtii in the absence of prominent ridges on the external surface of
the primary xylem, and from L. vasculare in the possession of a
A, B. Lepidodendron Veltheimianum. (Botany School, Cambridge.)
C. Lepidodendron macrophyllum. (British Museum. No. 377.)
x, Primary xylem; x2, secondary xylem; s, Stigmarian rootlet.
There can be little doubt that the petrified shoots described by
Williamson[384] from the Calciferous Sandstone beds of Burntisland as
Lepidodendron brevifolium are identical with specimens possessing the
external features of L. Veltheimianum. In 1872 Dawson expressed the
opinion that Williamson’s species should be referred to L. Veltheimianum,
and evidence subsequently obtained confirms this view. The stele of this
species is of the medullated type, differing from that of L. fuliginosum and
L. Harcourtii in the absence of prominent ridges on the external surface of
the primary xylem, and from L. vasculare in the possession of a
Page 211
parenchymatous pith. In younger twigs the cortex consists of fairly
homogeneous tissue, but in older branches there is a greater distinction
between a delicate middle cortex and a stronger outer cortex. Fig. 186, A,
represents a stem in which the vascular cylinder is composed of a primary
xylem ring, x, 1·5 mm. broad, succeeded by a zone of secondary wood 1·2
cm. in breadth. The junction between the primary and secondary xylem is
shown on a larger scale in fig. 186, B. The tissues abutting on the secondary
xylem have not been preserved; the outer cortex, which consists chiefly of
secondary elements, is divided superficially into unequal ridges
corresponding to the leaf-cushions which have been more or less obliterated
as the result of growth in thickness of the stem.
9. Lepidodendron Pedroanum (Carruthers).
In 1869 Mr Carruthers described some specimens of vegetative stems
and isolated sporangia, collected by Mr Plant in Brazil, as Flemingites
Pedroanus[385]. From a more recent account published by Zeiller[386] it is
clear that Carruthers’ species is a true Lepidodendron; an examination of the
type-specimens in the British Museum confirms this determination. The
contiguous leaf-cushions have rounded angles similar in form to those of
Lepidodendron Veltheimianum and L. dichotomum, but it is not unlikely that
the Brazilian plant is specifically distinct from European species. A figure
of one of the specimens on which Carruthers founded the species is given
by Arber[387] in his Glossopteris Flora. The Brazilian plant is chiefly
interesting as affording proof of the existence of Lepidodendron in the
southern hemisphere; the species has also been recognised in South Africa
from material collected by Mr Leslie at Vereeniging[388].
As Zeiller[389] has suggested, it is not improbable that the fossils described
by Renault[390] from Brazil as Lycopodiopsis Derbyi may be the petrified
stems of Lepidodendron Pedroanum. The structure of the central cylinder of
Renault’s species is of the type represented by L. Harcourtii; the xylem
forms a continuous ring and does not consist of separate strands of tracheae
as Renault believed.
10. Lepidodendron australe (M’Coy). Figs. 187, A–C.
Specimens described under this name are interesting rather on account of
their extended geographical range and geological antiquity than on
homogeneous tissue, but in older branches there is a greater distinction
between a delicate middle cortex and a stronger outer cortex. Fig. 186, A,
represents a stem in which the vascular cylinder is composed of a primary
xylem ring, x, 1·5 mm. broad, succeeded by a zone of secondary wood 1·2
cm. in breadth. The junction between the primary and secondary xylem is
shown on a larger scale in fig. 186, B. The tissues abutting on the secondary
xylem have not been preserved; the outer cortex, which consists chiefly of
secondary elements, is divided superficially into unequal ridges
corresponding to the leaf-cushions which have been more or less obliterated
as the result of growth in thickness of the stem.
9. Lepidodendron Pedroanum (Carruthers).
In 1869 Mr Carruthers described some specimens of vegetative stems
and isolated sporangia, collected by Mr Plant in Brazil, as Flemingites
Pedroanus[385]. From a more recent account published by Zeiller[386] it is
clear that Carruthers’ species is a true Lepidodendron; an examination of the
type-specimens in the British Museum confirms this determination. The
contiguous leaf-cushions have rounded angles similar in form to those of
Lepidodendron Veltheimianum and L. dichotomum, but it is not unlikely that
the Brazilian plant is specifically distinct from European species. A figure
of one of the specimens on which Carruthers founded the species is given
by Arber[387] in his Glossopteris Flora. The Brazilian plant is chiefly
interesting as affording proof of the existence of Lepidodendron in the
southern hemisphere; the species has also been recognised in South Africa
from material collected by Mr Leslie at Vereeniging[388].
As Zeiller[389] has suggested, it is not improbable that the fossils described
by Renault[390] from Brazil as Lycopodiopsis Derbyi may be the petrified
stems of Lepidodendron Pedroanum. The structure of the central cylinder of
Renault’s species is of the type represented by L. Harcourtii; the xylem
forms a continuous ring and does not consist of separate strands of tracheae
as Renault believed.
10. Lepidodendron australe (M’Coy). Figs. 187, A–C.
Specimens described under this name are interesting rather on account of
their extended geographical range and geological antiquity than on
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botanical grounds. The drawings reproduced in fig. 187 illustrate the
characteristic appearance of this Lower Carboniferous and Upper Devonian
type, as represented by a specimen recently described[391] from the Lower
Karroo (Dwyka) series, which is probably of Carboniferous age, near
Orange River Station, South Africa. The surface is divided into polygonal
or rhomboidal areas (figs. A and B) 8–9 mm. long and 7–8 mm. broad,
arranged in regular series and representing leaf-scars, comparable with
those of Sigillaria Brardi and other species, or possibly partially
decorticated leaf-cushions. A short distance below the apex of each area
there is a more or less circular prominence or depression (fig. 187, B) and
on a few of the areas there are indications of a groove (fig. A, g) extending
from the raised scar to the pointed base, as at g, g.
Fig. 187. Lepidodendron australe. Fig. A, nat. size.
characteristic appearance of this Lower Carboniferous and Upper Devonian
type, as represented by a specimen recently described[391] from the Lower
Karroo (Dwyka) series, which is probably of Carboniferous age, near
Orange River Station, South Africa. The surface is divided into polygonal
or rhomboidal areas (figs. A and B) 8–9 mm. long and 7–8 mm. broad,
arranged in regular series and representing leaf-scars, comparable with
those of Sigillaria Brardi and other species, or possibly partially
decorticated leaf-cushions. A short distance below the apex of each area
there is a more or less circular prominence or depression (fig. 187, B) and
on a few of the areas there are indications of a groove (fig. A, g) extending
from the raised scar to the pointed base, as at g, g.
Fig. 187. Lepidodendron australe. Fig. A, nat. size.
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In examining the graphitic layer on the surface of the South African
specimen shown in fig. 187, A, use was made of a method recently
described by Professor Nathorst[392]. A few drops of collodion were placed
on the surface, and after a short interval the film was removed and mounted
on a slide. The addition of a stain facilitated the microscopic examination
and the drawing of the collodion film. The cell-outlines (fig. 187, C) on the
surface of the polygonal areas may be those of the epidermis, but they were
more probably formed by a subepidermal tissue; the scar, which interrupts
the continuity of the flat surface, may mark the position of a leaf-base, or,
assuming a partial decortication to have occurred prior to fossilisation, it
may represent a gap in the cortical tissue caused by the decay of delicate
tissue which surrounded the vascular bundle of each leaf in its course
through the cortex of the stem. If the impression were that of the actual
surface of a Lepidodendron or a Sigillaria, we should expect to find traces
of the parichnos appearing on the leaf-scar as two small scars, one on each
side of the leaf-bundle. In specimens from Vereeniging described in
1897[393] as Sigillaria Brardi, which bear a superficial resemblance to that
shown in fig. A, the parichnos is clearly shown. On the other hand, an
impression of a partially decorticated Lepidodendroid stem need not
necessarily show the parichnos as a distinct feature: owing to its close
association with the leaf-trace in the outer cortex, before its separation in
the form of two diverging arms, it would not appear as a distinct gap apart
from that representing the leaf-bundle. The absence of the parichnos may be
regarded as a point in favour of the view that the impression is that of a
partially decorticated stem. Similarly, the absence of any demarcation
between a leaf-cushion and a true leaf-scar such as characterises the stems
of Lepidodendra and many Sigillariae is also favourable to the same
interpretation.
In 1872 Mr Carruthers[394] described some fossils from Queensland, some
of which appear to be identical with that shown in fig. 187 under the name
Lepidodendron nothum, Unger[395], a species founded on Upper Devonian
specimens from Thuringia. The Queensland plant is probably identical with
Dawson’s Canadian species, Leptophloeum rhombicum[396]. In 1874
M’Coy[397] instituted the name Lepidodendron australe for some Lower
Carboniferous specimens from Victoria, Australia: these are in all
probability identical with the Queensland fossils referred by Carruthers to
specimen shown in fig. 187, A, use was made of a method recently
described by Professor Nathorst[392]. A few drops of collodion were placed
on the surface, and after a short interval the film was removed and mounted
on a slide. The addition of a stain facilitated the microscopic examination
and the drawing of the collodion film. The cell-outlines (fig. 187, C) on the
surface of the polygonal areas may be those of the epidermis, but they were
more probably formed by a subepidermal tissue; the scar, which interrupts
the continuity of the flat surface, may mark the position of a leaf-base, or,
assuming a partial decortication to have occurred prior to fossilisation, it
may represent a gap in the cortical tissue caused by the decay of delicate
tissue which surrounded the vascular bundle of each leaf in its course
through the cortex of the stem. If the impression were that of the actual
surface of a Lepidodendron or a Sigillaria, we should expect to find traces
of the parichnos appearing on the leaf-scar as two small scars, one on each
side of the leaf-bundle. In specimens from Vereeniging described in
1897[393] as Sigillaria Brardi, which bear a superficial resemblance to that
shown in fig. A, the parichnos is clearly shown. On the other hand, an
impression of a partially decorticated Lepidodendroid stem need not
necessarily show the parichnos as a distinct feature: owing to its close
association with the leaf-trace in the outer cortex, before its separation in
the form of two diverging arms, it would not appear as a distinct gap apart
from that representing the leaf-bundle. The absence of the parichnos may be
regarded as a point in favour of the view that the impression is that of a
partially decorticated stem. Similarly, the absence of any demarcation
between a leaf-cushion and a true leaf-scar such as characterises the stems
of Lepidodendra and many Sigillariae is also favourable to the same
interpretation.
In 1872 Mr Carruthers[394] described some fossils from Queensland, some
of which appear to be identical with that shown in fig. 187 under the name
Lepidodendron nothum, Unger[395], a species founded on Upper Devonian
specimens from Thuringia. The Queensland plant is probably identical with
Dawson’s Canadian species, Leptophloeum rhombicum[396]. In 1874
M’Coy[397] instituted the name Lepidodendron australe for some Lower
Carboniferous specimens from Victoria, Australia: these are in all
probability identical with the Queensland fossils referred by Carruthers to
Page 214
Unger’s species, but as the identity of the German and Australian plants is
very doubtful[398] it is better to adopt M’Coy’s specific designation.
Krasser[399] has described a similar, but probably not specifically
identical, type from China; from Devonian rocks of Spitzbergen
Nathorst[400] has figured, under the name Bergeria, an example of this form
of stem, and Szajnocha[401] has described other specimens from Lower
Carboniferous strata in the Argentine.
Lepidodendron australe has been recorded from several Australian
localities[402] from strata below those containing the genus Glossopteris and
other members of the Glossopteris, or, as it has recently been re-christened,
the Gangamopteris[403] Flora.
viii. Fertile shoots of Lepidodendron.
A. Lepidostrobus.
The generic name Lepidostrobus was first used by Brongniart[404] for the
cones of Lepidodendron, the type-species of the genus being Lepidostrobus
ornatus, the designation given by the author of the genus to a Lepidostrobus
previously figured by Parkinson[405] in his Organic Remains of a Former
World. The generic name Flemingites proposed by Carruthers[406] in 1865,
under a misapprehension as to the nature of spores which he identified as
sporangia, was applied to specimens of true Lepidostrobi. Brongniart also
instituted the generic name Lepidophyllum for detached leaves of
Lepidodendron, both vegetative and fertile; the specimen figured by him in
1822 as Filicites (Glossopteris) dubius[407], and which was afterwards made
the type-species of the genus, was recognised as being a portion of the
lanceolate limb of a large single-veined sporophyll belonging to a species of
Lepidostrobus.
In an unusually large Lepidophyllum, or detached sporophyll of
Lepidostrobus, in the Manchester University Museum, the free laminar
portion reaches a length of 8 cm.
It is not uncommon to find Lepidodendron preserved in the form of a
shell of outer cortex, which has become separated along the phellogen from
the rest of the stem; as the result of compression the cylinder of bark may
very doubtful[398] it is better to adopt M’Coy’s specific designation.
Krasser[399] has described a similar, but probably not specifically
identical, type from China; from Devonian rocks of Spitzbergen
Nathorst[400] has figured, under the name Bergeria, an example of this form
of stem, and Szajnocha[401] has described other specimens from Lower
Carboniferous strata in the Argentine.
Lepidodendron australe has been recorded from several Australian
localities[402] from strata below those containing the genus Glossopteris and
other members of the Glossopteris, or, as it has recently been re-christened,
the Gangamopteris[403] Flora.
viii. Fertile shoots of Lepidodendron.
A. Lepidostrobus.
The generic name Lepidostrobus was first used by Brongniart[404] for the
cones of Lepidodendron, the type-species of the genus being Lepidostrobus
ornatus, the designation given by the author of the genus to a Lepidostrobus
previously figured by Parkinson[405] in his Organic Remains of a Former
World. The generic name Flemingites proposed by Carruthers[406] in 1865,
under a misapprehension as to the nature of spores which he identified as
sporangia, was applied to specimens of true Lepidostrobi. Brongniart also
instituted the generic name Lepidophyllum for detached leaves of
Lepidodendron, both vegetative and fertile; the specimen figured by him in
1822 as Filicites (Glossopteris) dubius[407], and which was afterwards made
the type-species of the genus, was recognised as being a portion of the
lanceolate limb of a large single-veined sporophyll belonging to a species of
Lepidostrobus.
In an unusually large Lepidophyllum, or detached sporophyll of
Lepidostrobus, in the Manchester University Museum, the free laminar
portion reaches a length of 8 cm.
It is not uncommon to find Lepidodendron preserved in the form of a
shell of outer cortex, which has become separated along the phellogen from
the rest of the stem; as the result of compression the cylinder of bark may
Page 215
assume the appearance of a flattened stem covered with leaf-cushions. A
specimen preserved in this way was described by E. Weiss as a cone of
Lomatophloios macrolepidotus Gold., and is quoted by Solms-Laubach and
other authors[408] as an example of an unusually large Lepidostrobus. An
examination of the type-specimen in the Bergakademie of Berlin convinced
me that Weiss had mistaken the partially destroyed leaf-cushions for
sporophylls, and Stigmarian rootlets, which had invaded the empty space,
for sporangia[409].
In external appearance some species of Lepidostrobus bear a superficial
resemblance to the cone of a Spruce Fir (Picea excelsa), but the surface of a
lycopodiaceous strobilus is usually covered by the overlapping and
upturned laminae which terminate the more or less horizontal sporangium-
bearing portion of the sporophyll.
Fig. 188 affords a good example of a long and narrow Lepidostrobus.
This specimen from the Middle Coal-Measures of Lancashire has a length
of 23 cm.; like other Lepidostrobi it is borne at the tip of a slender shoot.
The fossil is sufficiently well preserved to show the characteristic radially
elongated form of the large sporangia and the long and upturned distal
portions of the sporophylls.
We may briefly describe Lepidostrobus as follows:—Cylindrical strobili
consisting of an axis containing a single cylindrical stele which agrees
generally with that of the vegetative shoots of L. Harcourtii and other
species. The amount of parenchymatous pith varies in different forms; in
some the primary xylem is almost solid. The middle cortical region, which
has usually been destroyed before fossilisation, possesses the loose lacunar
structure characteristic of this region in the vegetative branches. The thicker
walled outer cortex is continued at the periphery into crowded, usually
spirally disposed sporophylls, each of which consists of a more or less
horizontal pedicel, which may be characterised by a keel-like median ridge
on its lower surface, while to the central region of the upper face is attached
a large radially elongated sporangium. One of the chief differences between
a Lepidodendron cone and those of the recent genus Lycopodium is the
greater radial elongation of the sporangia in the former. Some species of
Lepidostrobus may have been homosporous; some are known to be
heterosporous. In the latter the megasporangia borne on the lower
sporophylls usually contain several megaspores as in Isoetes (cf. fig. 133,
specimen preserved in this way was described by E. Weiss as a cone of
Lomatophloios macrolepidotus Gold., and is quoted by Solms-Laubach and
other authors[408] as an example of an unusually large Lepidostrobus. An
examination of the type-specimen in the Bergakademie of Berlin convinced
me that Weiss had mistaken the partially destroyed leaf-cushions for
sporophylls, and Stigmarian rootlets, which had invaded the empty space,
for sporangia[409].
In external appearance some species of Lepidostrobus bear a superficial
resemblance to the cone of a Spruce Fir (Picea excelsa), but the surface of a
lycopodiaceous strobilus is usually covered by the overlapping and
upturned laminae which terminate the more or less horizontal sporangium-
bearing portion of the sporophyll.
Fig. 188 affords a good example of a long and narrow Lepidostrobus.
This specimen from the Middle Coal-Measures of Lancashire has a length
of 23 cm.; like other Lepidostrobi it is borne at the tip of a slender shoot.
The fossil is sufficiently well preserved to show the characteristic radially
elongated form of the large sporangia and the long and upturned distal
portions of the sporophylls.
We may briefly describe Lepidostrobus as follows:—Cylindrical strobili
consisting of an axis containing a single cylindrical stele which agrees
generally with that of the vegetative shoots of L. Harcourtii and other
species. The amount of parenchymatous pith varies in different forms; in
some the primary xylem is almost solid. The middle cortical region, which
has usually been destroyed before fossilisation, possesses the loose lacunar
structure characteristic of this region in the vegetative branches. The thicker
walled outer cortex is continued at the periphery into crowded, usually
spirally disposed sporophylls, each of which consists of a more or less
horizontal pedicel, which may be characterised by a keel-like median ridge
on its lower surface, while to the central region of the upper face is attached
a large radially elongated sporangium. One of the chief differences between
a Lepidodendron cone and those of the recent genus Lycopodium is the
greater radial elongation of the sporangia in the former. Some species of
Lepidostrobus may have been homosporous; some are known to be
heterosporous. In the latter the megasporangia borne on the lower
sporophylls usually contain several megaspores as in Isoetes (cf. fig. 133,
Page 216
E). Beyond the distal end of the sporangium the sporophyll becomes
broader in a horizontal plane and is bent upwards as a lanceolate limb; it
may also be prolonged a short distance downwards as a bluntly triangular
expansion.
Fig. 188. Lepidostrobus. Middle Coal-Measures, Bardsley, Lancashire. From a specimen in
the Manchester Museum. (½ nat. size.)
There can be little doubt that the Palaeozoic Lepidodendra, like
Lycopodium cernuum (fig. 123) and other recent Lycopods, usually bore
their cones at the tips of slender shoots. The fertile shoot of Lepidophloios
scoticus shown in fig. 160, B, affords one of several instances supporting
broader in a horizontal plane and is bent upwards as a lanceolate limb; it
may also be prolonged a short distance downwards as a bluntly triangular
expansion.
Fig. 188. Lepidostrobus. Middle Coal-Measures, Bardsley, Lancashire. From a specimen in
the Manchester Museum. (½ nat. size.)
There can be little doubt that the Palaeozoic Lepidodendra, like
Lycopodium cernuum (fig. 123) and other recent Lycopods, usually bore
their cones at the tips of slender shoots. The fertile shoot of Lepidophloios
scoticus shown in fig. 160, B, affords one of several instances supporting
Page 217
this statement; similar examples are figured by Brongniart[410], Morris[411],
and by more recent writers. The apparently sessile cone figured by
Williamson[412] from a specimen in the Manchester Museum is certainly not
in situ, but is accidentally associated with the stem.
The general absence of secondary wood in the steles of Lepidostrobi is,
as Dr Kidston[413] points out, consistent with the view that the cones were
shed on maturity and that fertilisation probably took place on the ground, or
perhaps on the surface of the water where the slender hairs of the
megaspores (fig. 191, F, I) may have served to catch the microspores.
Fig. 189. Lepidostrobus. Section through the apical region of a cone above the axis.
(Manchester University Collection.)
Fig. 189 is an accurate representation of a transverse section, 6 mm. in
diameter, of what is no doubt the apical portion of a Lepidostrobus from the
Coal-Measures of Shore, Lancashire. The section cuts across the upturned
free laminae above the level of the apex of the cone-axis. Each lamina
and by more recent writers. The apparently sessile cone figured by
Williamson[412] from a specimen in the Manchester Museum is certainly not
in situ, but is accidentally associated with the stem.
The general absence of secondary wood in the steles of Lepidostrobi is,
as Dr Kidston[413] points out, consistent with the view that the cones were
shed on maturity and that fertilisation probably took place on the ground, or
perhaps on the surface of the water where the slender hairs of the
megaspores (fig. 191, F, I) may have served to catch the microspores.
Fig. 189. Lepidostrobus. Section through the apical region of a cone above the axis.
(Manchester University Collection.)
Fig. 189 is an accurate representation of a transverse section, 6 mm. in
diameter, of what is no doubt the apical portion of a Lepidostrobus from the
Coal-Measures of Shore, Lancashire. The section cuts across the upturned
free laminae above the level of the apex of the cone-axis. Each lamina
Page 218
contains a small vascular bundle composed of a few tracheae and some
thin-walled cells surrounded by delicate mesophyll tissue. Immediately in
front of the distal end of a sporangium a small ligule is borne on the upper
face of the sporophyll (fig. 191, A, B, l) occupying the same position as in
Selaginella (cf. fig. 131, F). Strands of vascular tissue pass in a steeply
ascending course from the xylem to the pedicels of sporophylls, finally
curving upwards and ending in the upper limb. Each vascular bundle
consists of a strand of xylem, apparently of mesarch structure, accompanied
by a few layers of parenchyma on its outer face and by a group of
cambiform elements, the whole being enclosed in a sheath of parenchyma
continuous with the inner cortex of the cone axis. The vascular bundle is
accompanied by a parichnos in the outer cortex and in the sporophyll.
Reference has already been made to the belief on the part of some
palaeobotanists that the large scars of Ulodendron represent attachment-
surfaces of sessile cones, and reasons have been given against the
acceptance of this view.
There is considerable range in the size of Lepidostrobi. An incomplete
specimen, 33 cm. long and 6 cm. broad, which may have been 50 cm. in
length, is described by Renault and Zeiller[414] from the Commentry Coal-
field. The larger cones afford a striking demonstration of the enormous
spore-output of some species of Lepidodendron.
Among the earliest accounts of the anatomy of Lepidostrobus are those
by Hooker[415] and Binney[416]. One of the specimens described by the former
author (fig. 190) affords an interesting example of an unusual manner of
fossilisation; a hollow stem or Lepidodendron is filled with sedimentary
material containing several pieces of Lepidostrobi in an approximately
vertical position.
thin-walled cells surrounded by delicate mesophyll tissue. Immediately in
front of the distal end of a sporangium a small ligule is borne on the upper
face of the sporophyll (fig. 191, A, B, l) occupying the same position as in
Selaginella (cf. fig. 131, F). Strands of vascular tissue pass in a steeply
ascending course from the xylem to the pedicels of sporophylls, finally
curving upwards and ending in the upper limb. Each vascular bundle
consists of a strand of xylem, apparently of mesarch structure, accompanied
by a few layers of parenchyma on its outer face and by a group of
cambiform elements, the whole being enclosed in a sheath of parenchyma
continuous with the inner cortex of the cone axis. The vascular bundle is
accompanied by a parichnos in the outer cortex and in the sporophyll.
Reference has already been made to the belief on the part of some
palaeobotanists that the large scars of Ulodendron represent attachment-
surfaces of sessile cones, and reasons have been given against the
acceptance of this view.
There is considerable range in the size of Lepidostrobi. An incomplete
specimen, 33 cm. long and 6 cm. broad, which may have been 50 cm. in
length, is described by Renault and Zeiller[414] from the Commentry Coal-
field. The larger cones afford a striking demonstration of the enormous
spore-output of some species of Lepidodendron.
Among the earliest accounts of the anatomy of Lepidostrobus are those
by Hooker[415] and Binney[416]. One of the specimens described by the former
author (fig. 190) affords an interesting example of an unusual manner of
fossilisation; a hollow stem or Lepidodendron is filled with sedimentary
material containing several pieces of Lepidostrobi in an approximately
vertical position.
Page 219
Fig. 190. Lepidodendron stem with Lepidostrobi. (After Hooker.)
A. Side-view showing leaf-cushions on the left-hand side and the Knorria condition
on the right.
B. View of transverse section; s, sections of Lepidostrobi.
The fact that Lepidostrobi usually occur as isolated specimens renders it
impossible in most cases to refer them to particular species of
Lepidodendron. Neither external features nor anatomical characters afford
satisfactory criteria by which to correlate vegetative and fertile shoots; in
some measure this is due to the imperfection of our knowledge as regards
the range of structure within the limits of species; it is also due to lack of
information as to the extent to which the transition from sterile to fertile
portions of a shoot is accompanied by anatomical differences. Prof.
A. Side-view showing leaf-cushions on the left-hand side and the Knorria condition
on the right.
B. View of transverse section; s, sections of Lepidostrobi.
The fact that Lepidostrobi usually occur as isolated specimens renders it
impossible in most cases to refer them to particular species of
Lepidodendron. Neither external features nor anatomical characters afford
satisfactory criteria by which to correlate vegetative and fertile shoots; in
some measure this is due to the imperfection of our knowledge as regards
the range of structure within the limits of species; it is also due to lack of
information as to the extent to which the transition from sterile to fertile
portions of a shoot is accompanied by anatomical differences. Prof.
Page 220
Williamson wrote: “I have for many years endeavoured to discover some
specific characters by which different Lepidostrobi can be distinguished and
identified, but thus far my efforts have been unsuccessful[417].” In a few
cases, such as those mentioned in the description of Lepidodendron
Veltheimianum and L. Wünschianum, it has been possible to correlate cones
and vegetative shoots.
The most complete account we possess of the anatomy of Lepidodendron
cones is that by Mr Maslen[418], who first demonstrated the occurrence of a
ligule on the sporophylls, and thus supplied a missing piece of evidence in
support of the generally accepted view as to the homology of the
sporangium-bearing members and foliage leaves.
i. Lepidostrobus variabilis (Lindley and Hutton).
1811. “Strobilus,” Parkinson, Organic Remains, Vol. i. p. 428, Pl. ix.
fig. 1.
1828. Lepidostrobus ornatus, Brongniart, Prodrome, p. 87.
1831. L. variabilis, Lindley and Hutton, Foss. Flora, Pls. x. xi.
1831. L. ornatus, Lindley and Hutton, Foss. Flora, Pl. xxvi.
1837. L. ornatus var. didymus, Ibid. Pl. clxiii.
1850. Arancarites Cordai, Unger, Genera et Spec. Plant. foss. p.
382.
1875. Lepidostrobus variabilis, Feistmantel, Palaeontographica, Vol.
lxiii. Pl. xliv.
1886. L. variabilis, Kidston, Cat. Palaeozoic Plants, p. 197.
1890. L. ornatus, Zeiller, Flor. Valenciennes, p. 497, Pl. lxxvi. figs.
5, 6.
—— L. variabilis, Zeiller, Flor. Valenciennes, p. 499, Pl. lxxvi. figs.
3, 4.
Under this specific name are included strobili from Upper Carboniferous
rocks which, in spite of minor differences, may be considered as one type.
The cylindrical cones vary considerably in size, some reaching a length of
50 cm. or more. The sporophylls are attached by a pedicel, 4–8 mm. long, at
right angles to the axis, while the distal portion forms an oval lanceolate
limb 10–20 mm. in length. The sporangia are 4–8 mm. long.
specific characters by which different Lepidostrobi can be distinguished and
identified, but thus far my efforts have been unsuccessful[417].” In a few
cases, such as those mentioned in the description of Lepidodendron
Veltheimianum and L. Wünschianum, it has been possible to correlate cones
and vegetative shoots.
The most complete account we possess of the anatomy of Lepidodendron
cones is that by Mr Maslen[418], who first demonstrated the occurrence of a
ligule on the sporophylls, and thus supplied a missing piece of evidence in
support of the generally accepted view as to the homology of the
sporangium-bearing members and foliage leaves.
i. Lepidostrobus variabilis (Lindley and Hutton).
1811. “Strobilus,” Parkinson, Organic Remains, Vol. i. p. 428, Pl. ix.
fig. 1.
1828. Lepidostrobus ornatus, Brongniart, Prodrome, p. 87.
1831. L. variabilis, Lindley and Hutton, Foss. Flora, Pls. x. xi.
1831. L. ornatus, Lindley and Hutton, Foss. Flora, Pl. xxvi.
1837. L. ornatus var. didymus, Ibid. Pl. clxiii.
1850. Arancarites Cordai, Unger, Genera et Spec. Plant. foss. p.
382.
1875. Lepidostrobus variabilis, Feistmantel, Palaeontographica, Vol.
lxiii. Pl. xliv.
1886. L. variabilis, Kidston, Cat. Palaeozoic Plants, p. 197.
1890. L. ornatus, Zeiller, Flor. Valenciennes, p. 497, Pl. lxxvi. figs.
5, 6.
—— L. variabilis, Zeiller, Flor. Valenciennes, p. 499, Pl. lxxvi. figs.
3, 4.
Under this specific name are included strobili from Upper Carboniferous
rocks which, in spite of minor differences, may be considered as one type.
The cylindrical cones vary considerably in size, some reaching a length of
50 cm. or more. The sporophylls are attached by a pedicel, 4–8 mm. long, at
right angles to the axis, while the distal portion forms an oval lanceolate
limb 10–20 mm. in length. The sporangia are 4–8 mm. long.
Page 221
The branched example figured by Lindley and Hutton[419] as a variety (L.
ornatus var. didymus) illustrates a phenomenon not uncommon in both
Palaeozoic and recent lycopodiaceous strobili.
Fig. 191. Lepidostrobus.
A–D. L. oldhamius.
B, C, D. From sections in the Binney Collection, Cambridge.
E. Megaspore. (After Kidston.)
F. Megaspore (Coal-Measures, Halifax). (After Williamson.)
G. Megaspore of Lepidostrobus foliaceus. (After Mrs Scott.)
H. Tangential section of sporangium. (After Bower.)
I. Part of sporangium wall, Sm, of the cone of Lepidodendron Veltheimianum,
enclosing two megaspores. (Cambridge Botany School.)
ii. Lepidostrobus oldhamius Williamson[420]. Fig. 191, A–D.
Williamson[421] instituted this term for strobili previously described by
Binney[422], without adequate evidence, as the cones of Lepidodendron
Harcourtii. In shape and in the main morphological features this type
resembles L. variabilis, which is however known only in the form of casts
ornatus var. didymus) illustrates a phenomenon not uncommon in both
Palaeozoic and recent lycopodiaceous strobili.
Fig. 191. Lepidostrobus.
A–D. L. oldhamius.
B, C, D. From sections in the Binney Collection, Cambridge.
E. Megaspore. (After Kidston.)
F. Megaspore (Coal-Measures, Halifax). (After Williamson.)
G. Megaspore of Lepidostrobus foliaceus. (After Mrs Scott.)
H. Tangential section of sporangium. (After Bower.)
I. Part of sporangium wall, Sm, of the cone of Lepidodendron Veltheimianum,
enclosing two megaspores. (Cambridge Botany School.)
ii. Lepidostrobus oldhamius Williamson[420]. Fig. 191, A–D.
Williamson[421] instituted this term for strobili previously described by
Binney[422], without adequate evidence, as the cones of Lepidodendron
Harcourtii. In shape and in the main morphological features this type
resembles L. variabilis, which is however known only in the form of casts
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and impressions. A cone of L. oldhamius, 2–3 cm. in diameter, possesses a
medullated stele consisting of a ring of primary xylem (fig. 191, D, x) with
exarch protoxylem and no secondary elements. Maslen found several short
tracheae at the periphery of the xylem and states that these led him to
compare the cone with the vegetative shoots of Lepidodendron vasculare,
but the common occurrence of such elements in different types of shoot
renders them of little or no specific value. The inner cortex is like that of
vegetative shoots of Lepidodendron and the middle cortex, which was no
doubt of the type described in Lepidostrobus Brownii, is represented by a
gap in the sections, beyond which is the stronger outer cortex (fig. 191, D)
passing into the horizontal pedicels of the sporophylls. The section of the
axis reproduced in fig. 191, D, was figured by Binney[423] as Lepidodendron
vasculare. The leaf-traces, several of which are seen in the middle cortical
region in fig. D, lt, consist of a strand of scalariform tracheae, with a
mesarch protoxylem, succeeded by a few parenchymatous cells; beyond
these there is usually a small gap which was originally occupied by a strand
of thin-walled cells. It is important to note that in one sporophyll-trace
figured by Maslen[424] there is a strand of thin-walled elongated elements
abutting on the xylem, which he describes as phloem. This tissue is
certainly more like true phloem than any which has hitherto been described
in the leaf-traces of vegetative shoots. The state of preservation is not,
however, sufficiently good to enable us to recognise undoubted phloem
features.
In such cones as I have examined no tissue has been seen which shows
the histological features characteristic of the secretory zone of vegetative
shoots: the “phloem” (Maslen) occupies the position in the sporophyll
bundle which in the vascular bundles of foliage leaves is occupied by a
dark-celled and partially disorganised tissue in continuity with the secretory
zone of the main stele. It may be that in the strobili this tissue occurred in a
modified form, but even assuming that the section figured by Maslen shows
true phloem, an assumption based on slender evidence, this is not sufficient
justification for the application of the term phloem to a tissue occupying a
corresponding position in vegetative shoots and distinguished by well-
marked histological features.
The sporophyll-traces, as seen in the outer cortex in fig. 191, D, are
partially surrounded by a large crescentic space, p, which was originally
medullated stele consisting of a ring of primary xylem (fig. 191, D, x) with
exarch protoxylem and no secondary elements. Maslen found several short
tracheae at the periphery of the xylem and states that these led him to
compare the cone with the vegetative shoots of Lepidodendron vasculare,
but the common occurrence of such elements in different types of shoot
renders them of little or no specific value. The inner cortex is like that of
vegetative shoots of Lepidodendron and the middle cortex, which was no
doubt of the type described in Lepidostrobus Brownii, is represented by a
gap in the sections, beyond which is the stronger outer cortex (fig. 191, D)
passing into the horizontal pedicels of the sporophylls. The section of the
axis reproduced in fig. 191, D, was figured by Binney[423] as Lepidodendron
vasculare. The leaf-traces, several of which are seen in the middle cortical
region in fig. D, lt, consist of a strand of scalariform tracheae, with a
mesarch protoxylem, succeeded by a few parenchymatous cells; beyond
these there is usually a small gap which was originally occupied by a strand
of thin-walled cells. It is important to note that in one sporophyll-trace
figured by Maslen[424] there is a strand of thin-walled elongated elements
abutting on the xylem, which he describes as phloem. This tissue is
certainly more like true phloem than any which has hitherto been described
in the leaf-traces of vegetative shoots. The state of preservation is not,
however, sufficiently good to enable us to recognise undoubted phloem
features.
In such cones as I have examined no tissue has been seen which shows
the histological features characteristic of the secretory zone of vegetative
shoots: the “phloem” (Maslen) occupies the position in the sporophyll
bundle which in the vascular bundles of foliage leaves is occupied by a
dark-celled and partially disorganised tissue in continuity with the secretory
zone of the main stele. It may be that in the strobili this tissue occurred in a
modified form, but even assuming that the section figured by Maslen shows
true phloem, an assumption based on slender evidence, this is not sufficient
justification for the application of the term phloem to a tissue occupying a
corresponding position in vegetative shoots and distinguished by well-
marked histological features.
The sporophyll-traces, as seen in the outer cortex in fig. 191, D, are
partially surrounded by a large crescentic space, p, which was originally
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occupied by the parichnos. The sporangia are attached along the middle line
of the sporophyll and, as in Lepidostrobus Brownii, a cushion of
parenchyma projects into the lower part of the sporangial cavity (fig. 191,
A, a; C, a).
The diagrammatic sketch of part of a section in the Binney Collection
reproduced in fig. 191, B, shows the position of the ligule, l. No
megaspores have been discovered in any specimens of this type; the
microspores, which occur both singly and in tetrads, have a length of 0·02–
0·03 mm.
The drawing shown in fig. 191, A, based on a section in the Binney
Collection, illustrates the general arrangement of the parts of a typical
Lepidostrobus. I have made use of this sketch instead of that given by
Maslen, as his figure conveys the idea that the sporophylls are superposed,
whereas, whether they are verticillate or spiral, a radial longitudinal section
would not cut successive sporangia in the same plane.
iii. Lepidostrobus Brownii (Brongn.).
In 1843 a specimen of a portion of a petrified cone was purchased by the
British Museum, assisted by the Marquis of Northampton and Robert
Brown, for £30 from a French dealer. This fossil, from an unknown locality,
was briefly described by Brown in 1851[425] and named by him
Triplosporites, but in a note added to his paper he expressed the opinion
that the generic designation Lepidostrobus would be more appropriate.
Brongniart afterwards named the cone Triplosporites Brownii[426], and
Schimper[427] described it in his Traité as Lepidostrobus Brownii. The type-
specimen is preserved in the British Museum and the Paris Museum
possesses a piece of the same fossil.
The central axis of the cone has a stele of the type characteristic of
Lepidodendron fuliginosum and L. Harcourtii, and the xylem is surrounded
by a thin-walled tissue described by Bower[428] as possibly phloem; but in
the absence of longitudinal sections it is impossible to say how far the tissue
external to the xylem agrees with that in Lepidodendron stems. The
sporophylls consist of a horizontal portion, to the upper face of which the
radially elongated sporangia are attached, one to each sporophyll; beyond
the distal end of the sporangium the sporophyll bends sharply upwards as a
of the sporophyll and, as in Lepidostrobus Brownii, a cushion of
parenchyma projects into the lower part of the sporangial cavity (fig. 191,
A, a; C, a).
The diagrammatic sketch of part of a section in the Binney Collection
reproduced in fig. 191, B, shows the position of the ligule, l. No
megaspores have been discovered in any specimens of this type; the
microspores, which occur both singly and in tetrads, have a length of 0·02–
0·03 mm.
The drawing shown in fig. 191, A, based on a section in the Binney
Collection, illustrates the general arrangement of the parts of a typical
Lepidostrobus. I have made use of this sketch instead of that given by
Maslen, as his figure conveys the idea that the sporophylls are superposed,
whereas, whether they are verticillate or spiral, a radial longitudinal section
would not cut successive sporangia in the same plane.
iii. Lepidostrobus Brownii (Brongn.).
In 1843 a specimen of a portion of a petrified cone was purchased by the
British Museum, assisted by the Marquis of Northampton and Robert
Brown, for £30 from a French dealer. This fossil, from an unknown locality,
was briefly described by Brown in 1851[425] and named by him
Triplosporites, but in a note added to his paper he expressed the opinion
that the generic designation Lepidostrobus would be more appropriate.
Brongniart afterwards named the cone Triplosporites Brownii[426], and
Schimper[427] described it in his Traité as Lepidostrobus Brownii. The type-
specimen is preserved in the British Museum and the Paris Museum
possesses a piece of the same fossil.
The central axis of the cone has a stele of the type characteristic of
Lepidodendron fuliginosum and L. Harcourtii, and the xylem is surrounded
by a thin-walled tissue described by Bower[428] as possibly phloem; but in
the absence of longitudinal sections it is impossible to say how far the tissue
external to the xylem agrees with that in Lepidodendron stems. The
sporophylls consist of a horizontal portion, to the upper face of which the
radially elongated sporangia are attached, one to each sporophyll; beyond
the distal end of the sporangium the sporophyll bends sharply upwards as a
Page 224
fairly stout lamina. The wall of the sporangium is composed of several
layers of cells, as shown in a drawing published by Bower[429]; in the interior
occur groups of microspores, and from a ridge of tissue which extends
along the whole length of the sporangium irregular trabeculae of sterile
tissue project into the sporangial cavity, as in Isoetes (fig. 191, H: cf. fig.
133, H).
Further information in regard to Lepidostrobus Brownii has recently been
supplied by Prof. Zeiller[430], who recognises the existence of a ligule, and
draws attention to some interesting histological features in the tissue of the
sporophylls[431].
Spores of Palaeozoic Lycopodiales.
The calcareous nodules from the Coal seams of Yorkshire and Lancashire
are rich in isolated spores, many of which are undoubtedly those of
Lepidostrobi. Examples of spores were figured by Morris[432] in 1840, and
their occurrence in coal has been described by several authors, one of the
earliest accounts being by Balfour[433]. The drawings of Palaeozoic and
recent spores published by Kidston and Bennie[434] demonstrate a striking
similarity between the megaspores of existing and extinct Lycopods, the
chief difference being the larger size of the fossils.
The general generic name Triletes, originally used by Reinsch[435], is a
convenient term by which to designate Pteridophytic spores which cannot
be referred to definite types.
It is usual to find more than four megaspores in each megasporangium in
Palaeozoic and not infrequently, as we have seen, in Mesozoic
lycopodiaceous strobili, but in some Palaeozoic cones, e.g. Bothrostrobus
(fig. 216) and Lepidostrobus foliaceus[436], a single tetrad only appears to
have reached maturity.
The occurrence of long simple or branched and sometimes capitate hairs
is a common feature of Carboniferous megaspores (fig. 191, E, F, I). It is
possible that these appendages served to catch the microspores, thus
facilitating fertilisation. A peculiar form of megaspore has been described
by Mrs Scott[437], and assigned by her to Lepidostrobus foliaceus, the
megasporangium of which apparently contained only four spores. As shown
in fig. 191, G, a large bladder-like appendage characterised by radiating
layers of cells, as shown in a drawing published by Bower[429]; in the interior
occur groups of microspores, and from a ridge of tissue which extends
along the whole length of the sporangium irregular trabeculae of sterile
tissue project into the sporangial cavity, as in Isoetes (fig. 191, H: cf. fig.
133, H).
Further information in regard to Lepidostrobus Brownii has recently been
supplied by Prof. Zeiller[430], who recognises the existence of a ligule, and
draws attention to some interesting histological features in the tissue of the
sporophylls[431].
Spores of Palaeozoic Lycopodiales.
The calcareous nodules from the Coal seams of Yorkshire and Lancashire
are rich in isolated spores, many of which are undoubtedly those of
Lepidostrobi. Examples of spores were figured by Morris[432] in 1840, and
their occurrence in coal has been described by several authors, one of the
earliest accounts being by Balfour[433]. The drawings of Palaeozoic and
recent spores published by Kidston and Bennie[434] demonstrate a striking
similarity between the megaspores of existing and extinct Lycopods, the
chief difference being the larger size of the fossils.
The general generic name Triletes, originally used by Reinsch[435], is a
convenient term by which to designate Pteridophytic spores which cannot
be referred to definite types.
It is usual to find more than four megaspores in each megasporangium in
Palaeozoic and not infrequently, as we have seen, in Mesozoic
lycopodiaceous strobili, but in some Palaeozoic cones, e.g. Bothrostrobus
(fig. 216) and Lepidostrobus foliaceus[436], a single tetrad only appears to
have reached maturity.
The occurrence of long simple or branched and sometimes capitate hairs
is a common feature of Carboniferous megaspores (fig. 191, E, F, I). It is
possible that these appendages served to catch the microspores, thus
facilitating fertilisation. A peculiar form of megaspore has been described
by Mrs Scott[437], and assigned by her to Lepidostrobus foliaceus, the
megasporangium of which apparently contained only four spores. As shown
in fig. 191, G, a large bladder-like appendage characterised by radiating
Page 225
veins is attached to the thick spore-coat; it is suggested that this excrescence
may be compared with the “swimming” apparatus of the recent water-fern
Azolla. The epithet swimming which it is customary to apply to the
appendages of Azolla megaspores would seem to be inappropriate if
Campbell[438] is correct in stating that spores of Azolla are incapable of
floating.
B. Spencerites.
Spencerites insignis (Williamson). Fig. 192.
1878. Lepidostrobus sp., Williamson, Phil. Trans. R. Soc., p. 340,
Pl. xxii.
1880. Lepidostrobus insignis, Williamson, Phil. Trans. R. Soc., p.
502, Pl. XV. figs. 8–12.
1889. Lepidodendron Spenceri, Williamson, Phil. Trans. R. Soc., p.
199, Pl. vii. figs. 20–22; Pl. viii. fig. 19.
1897. Spencerites insignis, Scott, Phil. Trans. p. 83, Pls. xii–xv.
Another type of lycopodiaceous strobilus, differing sufficiently from
Lepidostrobus to deserve a special generic designation, is that originally
described by Williamson[439], from the Lower Coal-Measures of Yorkshire,
as a type of Lepidostrobus, L. insignis, but afterwards[440] more fully
investigated and assigned to a new genus by Scott[441]. It should be pointed
out that in a later publication Williamson spoke of the lycopodiaceous axis,
which he suspected might belong to his L. insignis, as possibly worthy of
recognition as a distinct generic type.
may be compared with the “swimming” apparatus of the recent water-fern
Azolla. The epithet swimming which it is customary to apply to the
appendages of Azolla megaspores would seem to be inappropriate if
Campbell[438] is correct in stating that spores of Azolla are incapable of
floating.
B. Spencerites.
Spencerites insignis (Williamson). Fig. 192.
1878. Lepidostrobus sp., Williamson, Phil. Trans. R. Soc., p. 340,
Pl. xxii.
1880. Lepidostrobus insignis, Williamson, Phil. Trans. R. Soc., p.
502, Pl. XV. figs. 8–12.
1889. Lepidodendron Spenceri, Williamson, Phil. Trans. R. Soc., p.
199, Pl. vii. figs. 20–22; Pl. viii. fig. 19.
1897. Spencerites insignis, Scott, Phil. Trans. p. 83, Pls. xii–xv.
Another type of lycopodiaceous strobilus, differing sufficiently from
Lepidostrobus to deserve a special generic designation, is that originally
described by Williamson[439], from the Lower Coal-Measures of Yorkshire,
as a type of Lepidostrobus, L. insignis, but afterwards[440] more fully
investigated and assigned to a new genus by Scott[441]. It should be pointed
out that in a later publication Williamson spoke of the lycopodiaceous axis,
which he suspected might belong to his L. insignis, as possibly worthy of
recognition as a distinct generic type.
Page 226
Fig. 192. Spencerites insignis (Williamson). (After Miss Berridge.)
Of the two species included by Scott in his genus Spencerites only one, S.
insignis, need be considered. Since the publication of Scott’s paper our
knowledge of this type has been extended by Miss Berridge[442] and by Prof.
Lang[443].
The axis of the strobilus has a stele characterised by a pith of elongated
elements, most of which have thin walls; the xylem cylinder possesses
about twenty protoxylem strands forming more or less prominent exarch
ridges. The cortex exhibits a differentiation comparable with that in the
shoots of Lepidodendron. The sporophylls are arranged in alternating
Of the two species included by Scott in his genus Spencerites only one, S.
insignis, need be considered. Since the publication of Scott’s paper our
knowledge of this type has been extended by Miss Berridge[442] and by Prof.
Lang[443].
The axis of the strobilus has a stele characterised by a pith of elongated
elements, most of which have thin walls; the xylem cylinder possesses
about twenty protoxylem strands forming more or less prominent exarch
ridges. The cortex exhibits a differentiation comparable with that in the
shoots of Lepidodendron. The sporophylls are arranged in alternating
Page 227
verticils, each whorl consisting of ten members: the narrow horizontal
pedicel of a sporophyll, containing a single vascular bundle, as shown in
fig. 192, is expanded distally into a prominent upper lobe bearing a cushion
of small and delicate cells, to which the sporangium is attached, and
prolonged obliquely upwards as a free leaf-like lamina. The lower blunt
prolongation of the sporophylls appears to form a thick dorsal lobe, but, as
Lang has pointed out, it is highly probable that the present form of the
dorsal lobe is of secondary origin, and is “due to the disappearance of a
mucilage cavity from a large sporophyll base[444].” As Miss Berridge
remarks, the vascular bundle of the sporophyll does not give off a branch to
the ventral lobe and sporangium. In attachment, in shape, and in the
structure of the wall the sporangia differ markedly from those of
Lepidostrobi. The spores, which also constitute a characteristic feature of
the genus, have a maximum diameter of 0·14 mm.; they are described as
oblate spheroids with a broad hollow wing running round the equator (fig.
192) comparable with the air-sacs of the pollen of Pinus. Scott points out
that the spores of Spencerites are intermediate in size between the
microspores of Lepidodendron and the megaspores of Lycopodium; it is
difficult therefore to decide to which category they should be referred.
Spencerites is clearly distinct from Lepidostrobus; the absence of a ligule,
the manner of attachment of the sporangia, and the form and size of the
spores, are characteristic features.
A comparison of Spencerites with the strobili of Lycopodium cernuum
(figs. 123, 126–129) has recently been made by Lang, who draws attention
to the striking agreement as regards general plan and even detailed
structural features between the Palaeozoic and the recent type of strobilus.
It is interesting to find, as Lang points out, that in the original account of the
fossil cone by Williamson, the view is expressed that the sporangiophores
were confluent. An examination of the section figured by Williamson[445] led
Lang to confirm this opinion. It would be out of place to enter here into a
detailed comparison of Spencerites insignis and the cone of Lycopodium,
but the resemblances are considered by Lang to be sufficiently close to
suggest that the striking similarity may be indicative of relationship[446].
It is worthy of notice that the radial section of Spencerites (fig. 192)
presents a fairly close resemblance to a corresponding section through a
cone-scale of Agathis (Kauri Pine)[447]. In each case the megasporangium is
pedicel of a sporophyll, containing a single vascular bundle, as shown in
fig. 192, is expanded distally into a prominent upper lobe bearing a cushion
of small and delicate cells, to which the sporangium is attached, and
prolonged obliquely upwards as a free leaf-like lamina. The lower blunt
prolongation of the sporophylls appears to form a thick dorsal lobe, but, as
Lang has pointed out, it is highly probable that the present form of the
dorsal lobe is of secondary origin, and is “due to the disappearance of a
mucilage cavity from a large sporophyll base[444].” As Miss Berridge
remarks, the vascular bundle of the sporophyll does not give off a branch to
the ventral lobe and sporangium. In attachment, in shape, and in the
structure of the wall the sporangia differ markedly from those of
Lepidostrobi. The spores, which also constitute a characteristic feature of
the genus, have a maximum diameter of 0·14 mm.; they are described as
oblate spheroids with a broad hollow wing running round the equator (fig.
192) comparable with the air-sacs of the pollen of Pinus. Scott points out
that the spores of Spencerites are intermediate in size between the
microspores of Lepidodendron and the megaspores of Lycopodium; it is
difficult therefore to decide to which category they should be referred.
Spencerites is clearly distinct from Lepidostrobus; the absence of a ligule,
the manner of attachment of the sporangia, and the form and size of the
spores, are characteristic features.
A comparison of Spencerites with the strobili of Lycopodium cernuum
(figs. 123, 126–129) has recently been made by Lang, who draws attention
to the striking agreement as regards general plan and even detailed
structural features between the Palaeozoic and the recent type of strobilus.
It is interesting to find, as Lang points out, that in the original account of the
fossil cone by Williamson, the view is expressed that the sporangiophores
were confluent. An examination of the section figured by Williamson[445] led
Lang to confirm this opinion. It would be out of place to enter here into a
detailed comparison of Spencerites insignis and the cone of Lycopodium,
but the resemblances are considered by Lang to be sufficiently close to
suggest that the striking similarity may be indicative of relationship[446].
It is worthy of notice that the radial section of Spencerites (fig. 192)
presents a fairly close resemblance to a corresponding section through a
cone-scale of Agathis (Kauri Pine)[447]. In each case the megasporangium is
Page 228
attached by a narrow pedicel to the sporophyll and the latter has a similar
form in the two plants, though the extent of the resemblance is somewhat
lessened by Lang’s more complete account of the Palaeozoic type. If the
Spencerites sporangia possessed an integument the similarity with the
Agathis ovule would of course be much closer: recent palaeobotanical
investigations have shown that ovules and sporangia are not separated by
impassable barriers.
[Since this Chapter was set up in type a paper has appeared by Dr Bruno
Kubart on a new species of Spencerites spore, S. membranaceus, from the
Ostrau-Karwiner Coal-basin (Austria). The spores are larger than those of S.
insignis and in some the cells of a prothallus are preserved. Kubart figures a
section of a spore containing a group of seven cells, a central cell, which he
regards as an antheridial mother-cell, surrounded by six wall-cells. Kubart
(90).]
form in the two plants, though the extent of the resemblance is somewhat
lessened by Lang’s more complete account of the Palaeozoic type. If the
Spencerites sporangia possessed an integument the similarity with the
Agathis ovule would of course be much closer: recent palaeobotanical
investigations have shown that ovules and sporangia are not separated by
impassable barriers.
[Since this Chapter was set up in type a paper has appeared by Dr Bruno
Kubart on a new species of Spencerites spore, S. membranaceus, from the
Ostrau-Karwiner Coal-basin (Austria). The spores are larger than those of S.
insignis and in some the cells of a prothallus are preserved. Kubart figures a
section of a spore containing a group of seven cells, a central cell, which he
regards as an antheridial mother-cell, surrounded by six wall-cells. Kubart
(90).]
Page 229
Page 230
CHAPTER XVI.
Sigillaria.
i. General.
In view of the close resemblance between Lepidodendron and Sigillaria,
another lycopodiaceous plant characteristic of Carboniferous and Permian
floras, a comparatively brief description of the latter genus must suffice,
more particularly as Lepidodendron has received rather an undue share of
attention. Sigillaria, though abundantly represented among the relics of
Palaeozoic floras, especially those preserved in the Coal-Measures, is rare
in a petrified state, and our knowledge of its anatomy is far from complete.
In external form as in internal structure the difference between the two
genera are not such as enable us to draw in all cases a clearly defined line of
separation.
In the Antediluvian Phytology, Artis[448] figured a fossil from the
Carboniferous sandstones of Yorkshire which he called Euphorbites
vulgaris on account of a superficial resemblance to the stems of existing
succulent Euphorbias. Rhode[449] also compared Sigillarian stems with those
of recent Cacti. The specimen described by Artis is characterised by regular
vertical and slightly convex ribs bearing rows of leaf-scars in spiral series,
like those on the cushions of Lepidodendron. A few years earlier
Brongniart[450] had instituted the genus Sigillaria[451] for plants with ribbed
but not jointed stems bearing “disc-like impressions” (leaf-scars) disposed
in quincunx; the type-species named by the author of the genus Sigillaria
scutellata is identical, as Kidston[452] points out, with Euphorbites vulgaris
of Artis and with the plant afterwards figured by Brongniart as S.
pachyderma[453]. Brongniart in 1822 figured another type of stem
characterised by the absence of ribs and by prominent spirally arranged
cushions bearing relatively large leaf-scars like the upper part of the
specimen shown in fig. 203; this he named Clathraria Brardii, a well-
Sigillaria.
i. General.
In view of the close resemblance between Lepidodendron and Sigillaria,
another lycopodiaceous plant characteristic of Carboniferous and Permian
floras, a comparatively brief description of the latter genus must suffice,
more particularly as Lepidodendron has received rather an undue share of
attention. Sigillaria, though abundantly represented among the relics of
Palaeozoic floras, especially those preserved in the Coal-Measures, is rare
in a petrified state, and our knowledge of its anatomy is far from complete.
In external form as in internal structure the difference between the two
genera are not such as enable us to draw in all cases a clearly defined line of
separation.
In the Antediluvian Phytology, Artis[448] figured a fossil from the
Carboniferous sandstones of Yorkshire which he called Euphorbites
vulgaris on account of a superficial resemblance to the stems of existing
succulent Euphorbias. Rhode[449] also compared Sigillarian stems with those
of recent Cacti. The specimen described by Artis is characterised by regular
vertical and slightly convex ribs bearing rows of leaf-scars in spiral series,
like those on the cushions of Lepidodendron. A few years earlier
Brongniart[450] had instituted the genus Sigillaria[451] for plants with ribbed
but not jointed stems bearing “disc-like impressions” (leaf-scars) disposed
in quincunx; the type-species named by the author of the genus Sigillaria
scutellata is identical, as Kidston[452] points out, with Euphorbites vulgaris
of Artis and with the plant afterwards figured by Brongniart as S.
pachyderma[453]. Brongniart in 1822 figured another type of stem
characterised by the absence of ribs and by prominent spirally arranged
cushions bearing relatively large leaf-scars like the upper part of the
specimen shown in fig. 203; this he named Clathraria Brardii, a well-
Page 231
known and widely distributed Carboniferous and Permian species now
spoken of as Sigillaria Brardi (figs. 196, A–C; 203). A third type of stem
figured by Brongniart as Syringodendron striatum[454] agrees with Sigillaria
scutellata in having ribs, but differs in the substitution of narrow oval ridges
or depressions for leaf-scars; this is now recognised as a partially
decorticated Sigillaria, in which the vascular bundle of each leaf is
represented by a narrow ridge or depression. The name Syringodendron,
originally used by Sternberg, is conveniently applied to certain forms of
Sigillarian stems which have lost their superficial tissues. A fourth generic
name, Favularia, was instituted by Sternberg[455] for Sigillarian stems with
ribs covered with contiguous leaf-scars of hexagonal form and prominent
lateral angles (fig. 193, A; fig. 200, G).
spoken of as Sigillaria Brardi (figs. 196, A–C; 203). A third type of stem
figured by Brongniart as Syringodendron striatum[454] agrees with Sigillaria
scutellata in having ribs, but differs in the substitution of narrow oval ridges
or depressions for leaf-scars; this is now recognised as a partially
decorticated Sigillaria, in which the vascular bundle of each leaf is
represented by a narrow ridge or depression. The name Syringodendron,
originally used by Sternberg, is conveniently applied to certain forms of
Sigillarian stems which have lost their superficial tissues. A fourth generic
name, Favularia, was instituted by Sternberg[455] for Sigillarian stems with
ribs covered with contiguous leaf-scars of hexagonal form and prominent
lateral angles (fig. 193, A; fig. 200, G).
Page 232
Fig. 193.
A. Sigillaria elegans Brongn.
B. Sigillaria rugosa Brongn. Middle Coal-Measures.
C. Omphalophloios anglicus Kidst. Barnsley.
D. Sigillaria elegans Brongn.
E. Sigillaria tessellata Brongn.
(A, B, C, E, about ¾ nat. size. Dr Kidston’s Collection.)
The generic or sub-generic title Rhytidolepis, also instituted by Sternberg,
is applied to ribbed Sigillarian stems such as S. scutellata, S. rugosa (fig.
193, B), S. mammillaris (fig. 195), or S. laevigata (fig. 196, D).
A. Sigillaria elegans Brongn.
B. Sigillaria rugosa Brongn. Middle Coal-Measures.
C. Omphalophloios anglicus Kidst. Barnsley.
D. Sigillaria elegans Brongn.
E. Sigillaria tessellata Brongn.
(A, B, C, E, about ¾ nat. size. Dr Kidston’s Collection.)
The generic or sub-generic title Rhytidolepis, also instituted by Sternberg,
is applied to ribbed Sigillarian stems such as S. scutellata, S. rugosa (fig.
193, B), S. mammillaris (fig. 195), or S. laevigata (fig. 196, D).
Page 233
Goldenberg[456] proposed the name Leiodermaria for smooth Sigillarian
stems with leaf-scars not in contact with one another (fig. 196, C).
The shoot system of Sigillaria consisted of a stout stem tapering upwards
to a height of 100 feet[457] or more as an unbranched column, with its dome-
shaped apex[458] covered with linear grass-like leaves or, in some species,
such as Sigillaria Brardi[459], S. Eugenii[460], etc., the main trunk was
occasionally divided by apparently equal dichotomy. The younger portions
of the stem or branches were in some species clothed with leaves separated
by a narrow zigzag groove surrounding their hexagonal bases, while in
other forms each leaf was seated on a more or less prominent cushion
having the form illustrated by Sigillaria McMurtriei (fig. 194) or by the
example represented in fig. 200, H; or as in the ribbed species shown in
figs. 193, B, and 195, the leaves in vertical series were separated from one
another by longer portions of the ribs. As in Lepidodendron the cushions are
frequently characterised by irregular transverse wrinklings and other[461]
surface-ornamentation which in some instances at least may have been
produced as the result of post-mortem shrinkage of superficial tissue. From
the rarity of shoots with the foliage attached, it would seem that the leaves
persisted for a comparatively short time and were cut off by an absciss-layer
leaving behind a well-marked leaf-scar area. The linear leaves, reaching in
rare cases a length of one metre (e.g. S. lepidodendrifolia) but usually much
shorter, possessed a single median bundle, and the lower face was
characterised by two stomatal grooves and a median keel. It is not
uncommon to find leaf-bases of Sigillaria detached from the stem and
preserved as separate impressions. The term Sigillariophyllum used by
Grand’Eury[462] may be applied to detached leaves, though it is by no means
easy to distinguish between the foliage of Sigillaria and Lepidodendron. A
comparison of a typical species of Sigillaria, such as S. rugosa (fig. 193, B)
or S. Brardi (fig. 196, A–C) with a typical Lepidodendron reveals obvious
differences in the form of the leaf-cushion, but in some cases the distinction
becomes purely arbitrary.
stems with leaf-scars not in contact with one another (fig. 196, C).
The shoot system of Sigillaria consisted of a stout stem tapering upwards
to a height of 100 feet[457] or more as an unbranched column, with its dome-
shaped apex[458] covered with linear grass-like leaves or, in some species,
such as Sigillaria Brardi[459], S. Eugenii[460], etc., the main trunk was
occasionally divided by apparently equal dichotomy. The younger portions
of the stem or branches were in some species clothed with leaves separated
by a narrow zigzag groove surrounding their hexagonal bases, while in
other forms each leaf was seated on a more or less prominent cushion
having the form illustrated by Sigillaria McMurtriei (fig. 194) or by the
example represented in fig. 200, H; or as in the ribbed species shown in
figs. 193, B, and 195, the leaves in vertical series were separated from one
another by longer portions of the ribs. As in Lepidodendron the cushions are
frequently characterised by irregular transverse wrinklings and other[461]
surface-ornamentation which in some instances at least may have been
produced as the result of post-mortem shrinkage of superficial tissue. From
the rarity of shoots with the foliage attached, it would seem that the leaves
persisted for a comparatively short time and were cut off by an absciss-layer
leaving behind a well-marked leaf-scar area. The linear leaves, reaching in
rare cases a length of one metre (e.g. S. lepidodendrifolia) but usually much
shorter, possessed a single median bundle, and the lower face was
characterised by two stomatal grooves and a median keel. It is not
uncommon to find leaf-bases of Sigillaria detached from the stem and
preserved as separate impressions. The term Sigillariophyllum used by
Grand’Eury[462] may be applied to detached leaves, though it is by no means
easy to distinguish between the foliage of Sigillaria and Lepidodendron. A
comparison of a typical species of Sigillaria, such as S. rugosa (fig. 193, B)
or S. Brardi (fig. 196, A–C) with a typical Lepidodendron reveals obvious
differences in the form of the leaf-cushion, but in some cases the distinction
becomes purely arbitrary.
Page 234
Fig. 194. Sigillaria McMurtriei Kidst. From a specimen from the Upper Coal-Measures of
Radstock, in the British Museum (V. 952). Nat. size.
Fig. 195. Sigillaria mammillaris. (Rhytidolepis form.) From a specimen in the Manchester
Museum. p, parichnos; l, ligule-pit; t, leaf-trace; c, cushion; s, leaf-scar.
Radstock, in the British Museum (V. 952). Nat. size.
Fig. 195. Sigillaria mammillaris. (Rhytidolepis form.) From a specimen in the Manchester
Museum. p, parichnos; l, ligule-pit; t, leaf-trace; c, cushion; s, leaf-scar.
Page 235
Fig. 196.
A–C. Sigillaria Brardi. (A after Germar; B, C after Zeiller.)
D. Sigillaria laevigata.
E. Lepidodendron Wortheni (D and E after Zeiller).
Immediately above the centre of the upper boundary of a Sigillarian leaf-
scar a ligule pit may often be detected, as shown in fig. 195, l, and in some
cases, e.g. a specimen figured by Germar[463] (fig. 196, A) as Sigillaria
spinulosa (identical with S. Brardi), some circular scars with a central pit
surrounded by a raised rim occur on the surface of the stem, either singly or
in pairs, near the leaf-scars; these, it is suggested, may represent the
position of adventitious roots or, as Germar thought, of some deciduous
spinous processes. The leaf-scars are frequently hexagonal in shape, with
the lateral angles either rounded (fig. 200, F) or sharply pointed (fig. 200,
A–C. Sigillaria Brardi. (A after Germar; B, C after Zeiller.)
D. Sigillaria laevigata.
E. Lepidodendron Wortheni (D and E after Zeiller).
Immediately above the centre of the upper boundary of a Sigillarian leaf-
scar a ligule pit may often be detected, as shown in fig. 195, l, and in some
cases, e.g. a specimen figured by Germar[463] (fig. 196, A) as Sigillaria
spinulosa (identical with S. Brardi), some circular scars with a central pit
surrounded by a raised rim occur on the surface of the stem, either singly or
in pairs, near the leaf-scars; these, it is suggested, may represent the
position of adventitious roots or, as Germar thought, of some deciduous
spinous processes. The leaf-scars are frequently hexagonal in shape, with
the lateral angles either rounded (fig. 200, F) or sharply pointed (fig. 200,
Page 236
G, H); each scar bears three smaller scars as in Lepidodendron, a central
circular, oval or crescentic leaf-trace scar and larger oval or slightly curved
scars formed by the two parichnos arms (fig. 195, p). The larger size of the
parichnos arms, the individual cells of which may often be detected as a
fine punctation, is a distinguishing feature of the genus, but otherwise the
structure is very similar to that in Lepidodendron. As shown in figs. 195,
200, F, G, the three scars may occur nearer the upper than the lower margin
of the leaf-base area.
Lepidodendron Wortheni[464] (fig. 196, E), described from North America
by Lesquereux[465], by Zeiller[466] from France, and by Kidston[467] from the
Upper and Middle Coal-Measures of England, may be quoted as a
Lepidodendron bearing a close resemblance to Sigillaria. The shoots bear
cushions two or three times as long as broad and without the usual median
division, but with numerous irregular and discontinuous transverse
wrinklings. Lepidodendron Peachii Kidston[468] affords another example of
a form agreeing both with Sigillaria and with Lepidodendron. An Upper
Devonian type described by White[469] as Archaeosigillaria primaeva
affords a striking instance of the combination on one stem of Sigillarian and
Lepidodendroid leaf-cushions.
The difference between the original surface of a Sigillaria stem and that
of partially decorticated specimens is seen in figs. 196, C and D; in fig. C
the bark of Sigillaria Brardi shows the characteristic wrinklings of the
superficial tissue, while at a slightly lower level the leaf-scars are replaced
by the parichnos casts, a, and fine longitudinal striations represent the
elongated phelloderm cells laid bare by the exfoliation of the surface-layers.
Similarly, in the rib of Sigillaria laevigata (fig. 196, D) the parichnos arms,
p, and the longitudinal striations are exposed at the lower level, while the
surface is smooth and bears rows of widely separated leaf-scars.
circular, oval or crescentic leaf-trace scar and larger oval or slightly curved
scars formed by the two parichnos arms (fig. 195, p). The larger size of the
parichnos arms, the individual cells of which may often be detected as a
fine punctation, is a distinguishing feature of the genus, but otherwise the
structure is very similar to that in Lepidodendron. As shown in figs. 195,
200, F, G, the three scars may occur nearer the upper than the lower margin
of the leaf-base area.
Lepidodendron Wortheni[464] (fig. 196, E), described from North America
by Lesquereux[465], by Zeiller[466] from France, and by Kidston[467] from the
Upper and Middle Coal-Measures of England, may be quoted as a
Lepidodendron bearing a close resemblance to Sigillaria. The shoots bear
cushions two or three times as long as broad and without the usual median
division, but with numerous irregular and discontinuous transverse
wrinklings. Lepidodendron Peachii Kidston[468] affords another example of
a form agreeing both with Sigillaria and with Lepidodendron. An Upper
Devonian type described by White[469] as Archaeosigillaria primaeva
affords a striking instance of the combination on one stem of Sigillarian and
Lepidodendroid leaf-cushions.
The difference between the original surface of a Sigillaria stem and that
of partially decorticated specimens is seen in figs. 196, C and D; in fig. C
the bark of Sigillaria Brardi shows the characteristic wrinklings of the
superficial tissue, while at a slightly lower level the leaf-scars are replaced
by the parichnos casts, a, and fine longitudinal striations represent the
elongated phelloderm cells laid bare by the exfoliation of the surface-layers.
Similarly, in the rib of Sigillaria laevigata (fig. 196, D) the parichnos arms,
p, and the longitudinal striations are exposed at the lower level, while the
surface is smooth and bears rows of widely separated leaf-scars.
Page 237
Fig. 197. Carica sp. From the Royal Gardens, Kew. (Much reduced.) M.S.
The older part of a Sigillarian stem may present an appearance very
different from that of the younger shoots. The leaf-cushions may be
stretched apart as the result of elongation and increase in girth, while in
some cases the arrangement of the leaf-scars may vary on the same axis as
the result of inequalities in growth or changing climatic conditions. The
contiguous arrangement of the leaf-scars and narrow cushions characteristic
of the Clathrarian form of stem, as was first demonstrated by Weiss[470], and
afterwards illustrated by Zeiller[471] and Kidston, may be gradually replaced
The older part of a Sigillarian stem may present an appearance very
different from that of the younger shoots. The leaf-cushions may be
stretched apart as the result of elongation and increase in girth, while in
some cases the arrangement of the leaf-scars may vary on the same axis as
the result of inequalities in growth or changing climatic conditions. The
contiguous arrangement of the leaf-scars and narrow cushions characteristic
of the Clathrarian form of stem, as was first demonstrated by Weiss[470], and
afterwards illustrated by Zeiller[471] and Kidston, may be gradually replaced
Page 238
(on the same specimen) by a more distant disposition of the leaf-scars
separated by a smooth intervening surface of bark. The specimen of S.
Brardi reproduced in part in fig. 203, and first figured by Kidston, affords
an example of three “species” on one piece of stem, S. Brardi Brongn., S.
denudata Goepp. and S. rhomboidea Brongn.[472]
The piece of Carica stem, represented in fig. 197, illustrates the danger
of trusting to the disposition of leaves as a specific criterion.
Similarly, in the ribbed forms the degree of separation of the leaf-scars is
by no means uniform in a single species[473]. Some authors have adopted a
two-fold classification of Sigillarian stems proposed by the late Prof.
Weiss[474] of Berlin, who divided the Sigillariae into (A) Sub-Sigillariae,
comprising Leiodermariae and Cancellatae, and (B) Eu-Sigillariae,
including Favulariae and Rhytidolepis. Grand’Eury[475] adopts the terms
Rhytidolepis and Leiodermaria for ribbed and smooth stems respectively,
the type to which the name Clathraria was applied by Brongniart being in
some cases at least the young form of Leiodermarian stems. While
recognising the artificial distinction implied by such terms as Rhytidolepis,
Leiodermaria, and other sub-generic titles, we may conveniently speak of
the two main types of Sigillaria stems as ribbed and smooth.
Still older stems of Sigillaria are not uncommon from which the leaf-
scars and other superficial tissues have been exfoliated, leaving exposed a
longitudinally fissured surface of secondary cortex characterised by pairs of
considerably enlarged parichnos strands (fig. 198) which are sometimes
partially or wholly fused into one (Syringodendron state of Sigillaria). The
single or double nature of the elliptical or circular parichnos areas is
doubtless due to the degree of exfoliation, which may extend sufficiently
deep into the cortex to reach the level of the parichnos before the single
strand has bifurcated (cf. Lepidodendron, p. 100). In the Museums of
Manchester, Newcastle, and other places casts of large Sigillaria stems may
be seen, which illustrate the differences in breadth and regularity of the
vertical ribs, and in the size and shape of the parichnos areas in different
regions of a partially decorticated stem. A cast of a ribbed species in the
Manchester Museum, having a length of 185 cm. and a breadth of 56 cm.,
shows in the upper portion straight vertical grooves and broad ribs bearing
pairs of parichnos scars 11 mm. long; in the lower portion the ribs tend to
become obliterated and the parichnos scars, 2 cm. in length, may be
separated by a smooth intervening surface of bark. The specimen of S.
Brardi reproduced in part in fig. 203, and first figured by Kidston, affords
an example of three “species” on one piece of stem, S. Brardi Brongn., S.
denudata Goepp. and S. rhomboidea Brongn.[472]
The piece of Carica stem, represented in fig. 197, illustrates the danger
of trusting to the disposition of leaves as a specific criterion.
Similarly, in the ribbed forms the degree of separation of the leaf-scars is
by no means uniform in a single species[473]. Some authors have adopted a
two-fold classification of Sigillarian stems proposed by the late Prof.
Weiss[474] of Berlin, who divided the Sigillariae into (A) Sub-Sigillariae,
comprising Leiodermariae and Cancellatae, and (B) Eu-Sigillariae,
including Favulariae and Rhytidolepis. Grand’Eury[475] adopts the terms
Rhytidolepis and Leiodermaria for ribbed and smooth stems respectively,
the type to which the name Clathraria was applied by Brongniart being in
some cases at least the young form of Leiodermarian stems. While
recognising the artificial distinction implied by such terms as Rhytidolepis,
Leiodermaria, and other sub-generic titles, we may conveniently speak of
the two main types of Sigillaria stems as ribbed and smooth.
Still older stems of Sigillaria are not uncommon from which the leaf-
scars and other superficial tissues have been exfoliated, leaving exposed a
longitudinally fissured surface of secondary cortex characterised by pairs of
considerably enlarged parichnos strands (fig. 198) which are sometimes
partially or wholly fused into one (Syringodendron state of Sigillaria). The
single or double nature of the elliptical or circular parichnos areas is
doubtless due to the degree of exfoliation, which may extend sufficiently
deep into the cortex to reach the level of the parichnos before the single
strand has bifurcated (cf. Lepidodendron, p. 100). In the Museums of
Manchester, Newcastle, and other places casts of large Sigillaria stems may
be seen, which illustrate the differences in breadth and regularity of the
vertical ribs, and in the size and shape of the parichnos areas in different
regions of a partially decorticated stem. A cast of a ribbed species in the
Manchester Museum, having a length of 185 cm. and a breadth of 56 cm.,
shows in the upper portion straight vertical grooves and broad ribs bearing
pairs of parichnos scars 11 mm. long; in the lower portion the ribs tend to
become obliterated and the parichnos scars, 2 cm. in length, may be
Page 239
partially fused and arranged in much less regular vertical series. A feature of
these older ribbed Sigillarian stems is the increase in the number of the ribs
from below upwards. Kidston[476] has described a specimen in the
Sunderland Museum, 6 feet 6 inches long, with a circumference at the
slightly bottle-shaped base of 5 feet. On the lower portion of the stem there
are 29 broad ribs; about one-third the height many of these bifurcate,
producing as many as 40 ribs in the upper part where the cast has a
circumference of 3 feet. The increase in number of the ribs is due in part to
bifurcation, but also to the intercalation of new ones. As Kidston points out,
this example shows that as a stem grew in length additional leaves were
developed at the apex. A similar stem, which illustrates very clearly the
increase in the number of ribs from below upwards, may be seen in the
Newcastle Museum.
Grand’Eury[477] has described an example of an old stem of a ribless
species of Sigillaria, Syringodendron bioculatum, bearing single and double
parichnos areas of nearly circular form and with a diameter of 1–2 cm. In a
specimen figured by Renault and Roche[478] (Syringodendron esnostense)
from the Culm strata in France, the parichnos scars reach a length of 3 cm.
As seen in the fragment of a ribbed Sigillaria represented in fig. 198, the
large parichnos areas exhibit a distinct surface pitting in contrast to the fine
longitudinal striation of the rib; the difference in surface-appearance is due
to the nature of the tissue, which in the parichnos consists of fairly large
parenchymatous elements with groups of secretory cells[479], and in the
exposed cortex of elongated elements. The vertical line in the middle of fig.
198, which occurs in the middle of the rib, has probably been formed by
splitting of the bark.
these older ribbed Sigillarian stems is the increase in the number of the ribs
from below upwards. Kidston[476] has described a specimen in the
Sunderland Museum, 6 feet 6 inches long, with a circumference at the
slightly bottle-shaped base of 5 feet. On the lower portion of the stem there
are 29 broad ribs; about one-third the height many of these bifurcate,
producing as many as 40 ribs in the upper part where the cast has a
circumference of 3 feet. The increase in number of the ribs is due in part to
bifurcation, but also to the intercalation of new ones. As Kidston points out,
this example shows that as a stem grew in length additional leaves were
developed at the apex. A similar stem, which illustrates very clearly the
increase in the number of ribs from below upwards, may be seen in the
Newcastle Museum.
Grand’Eury[477] has described an example of an old stem of a ribless
species of Sigillaria, Syringodendron bioculatum, bearing single and double
parichnos areas of nearly circular form and with a diameter of 1–2 cm. In a
specimen figured by Renault and Roche[478] (Syringodendron esnostense)
from the Culm strata in France, the parichnos scars reach a length of 3 cm.
As seen in the fragment of a ribbed Sigillaria represented in fig. 198, the
large parichnos areas exhibit a distinct surface pitting in contrast to the fine
longitudinal striation of the rib; the difference in surface-appearance is due
to the nature of the tissue, which in the parichnos consists of fairly large
parenchymatous elements with groups of secretory cells[479], and in the
exposed cortex of elongated elements. The vertical line in the middle of fig.
198, which occurs in the middle of the rib, has probably been formed by
splitting of the bark.
Page 240
Fig. 198. Sigillaria with large parichnos areas. (⅓ nat. size.) M.S.
Grand’Eury’s description of fossil forests of Sigillariae in the rocks of the
St Étienne[480] district affords a striking picture of these arborescent
Pteridophytes; he speaks of the stems of some of the trees as swollen like a
bottle at the base, characterised by the Syringodendron features and
terminating below in short repeatedly forked roots of the type known as
Stigmariopsis. Other specimens of Sigillaria stumps show a marked
decrease in girth towards the base; this tapered form is regarded by
Grand’Eury as the result of the development of aerial columnar stems from
underground rhizomes.
The nature of the root-like organs of Sigillaria is dealt with in the sequel:
a brief reference may, however, be made to the occurrence of stumps of
vertical trunks which pass downwards into regularly forked and spreading
arms. These arms lie almost horizontally in the sand or mud like the
underground rhizomes of Phragmites and other recent plants growing in
swampy situations where water is abundant and where deeper penetration
of the soil would expose them to an insufficient supply of oxygen[481]. It is
certain that Sigillaria had no tap-root, but was supported on spreading
subterranean organs bearing spirally disposed long and slender rootlets
which absorbed water from a swampy soil.
Grand’Eury’s description of fossil forests of Sigillariae in the rocks of the
St Étienne[480] district affords a striking picture of these arborescent
Pteridophytes; he speaks of the stems of some of the trees as swollen like a
bottle at the base, characterised by the Syringodendron features and
terminating below in short repeatedly forked roots of the type known as
Stigmariopsis. Other specimens of Sigillaria stumps show a marked
decrease in girth towards the base; this tapered form is regarded by
Grand’Eury as the result of the development of aerial columnar stems from
underground rhizomes.
The nature of the root-like organs of Sigillaria is dealt with in the sequel:
a brief reference may, however, be made to the occurrence of stumps of
vertical trunks which pass downwards into regularly forked and spreading
arms. These arms lie almost horizontally in the sand or mud like the
underground rhizomes of Phragmites and other recent plants growing in
swampy situations where water is abundant and where deeper penetration
of the soil would expose them to an insufficient supply of oxygen[481]. It is
certain that Sigillaria had no tap-root, but was supported on spreading
subterranean organs bearing spirally disposed long and slender rootlets
which absorbed water from a swampy soil.
Page 241
Fig. 199. Partially decorticated stem of Sigillaria showing two zones of cone-scars. From a
cast in the Sedgwick Museum, Cambridge. M.S. (⅕ nat. size.)
The regularity of the leaf-scar series on a Sigillarian stem may be
interrupted by the occurrence of oval scars with a central scar and
surrounding groove (fig. 193, E); these occur in zones at more or less
regular intervals on the stem, as seen in the partially decorticated cast
represented in fig. 199. Zeiller has pointed out that the rows of oval or
circular scars, which mark the position of caducous stalked strobili, may
occur between the leaf-scars in vertical series, each of which may include as
cast in the Sedgwick Museum, Cambridge. M.S. (⅕ nat. size.)
The regularity of the leaf-scar series on a Sigillarian stem may be
interrupted by the occurrence of oval scars with a central scar and
surrounding groove (fig. 193, E); these occur in zones at more or less
regular intervals on the stem, as seen in the partially decorticated cast
represented in fig. 199. Zeiller has pointed out that the rows of oval or
circular scars, which mark the position of caducous stalked strobili, may
occur between the leaf-scars in vertical series, each of which may include as
Page 242
many as 20 scars, while in other cases a single series of such cone-scars
may encircle the stem[482]. The zones are usually of uneven breadth, as in S.
Brardi, and their occurrence produces some deformation of the adjacent
leaf-scars.
By the earlier writers Sigillaria was compared with succulent
Euphorbias, Cacti, and Palms; Brongniart[483] at first included undoubted
Sigillarian stems among Ferns, but after investigating an agatized stem from
Autun, he referred Sigillaria to the Gymnosperms[484] on the ground that it
had the power of producing secondary wood. It was then supposed that
Lepidodendron possessed only primary xylem, and that the presence of a
vascular meristem in Sigillaria necessitated its separation from the
lycopodiaceous genus Lepidodendron and its inclusion in the higher plants.
By slow degrees it was recognised, as in the parallel case of the genus
Calamites, that the presence or absence of secondary vascular tissue is a
character of small importance. Williamson, whose anatomical researches
played the most important part in ridding the minds of palaeobotanists of
the superstition that secondary growth in thickness is a monopoly of the
Phanerogams, spoke in 1883 of the conflict as to the affinities of
Lepidodendron and Sigillaria as virtually over but leaving here and there
“the ground-swell of a stormy past[485].” In 1872 the same author had
written: “If then I am correct in thus bringing the Lepidodendra and
Sigillariae into such close affinity, there is an end of M. Brongniart’s theory,
that the latter were gymnospermous exogens, because the cryptogamic
character of the former is disputed by no one; we must rather conclude as I
have done that the entire series represents, along with the Calamites, an
exogenous group of Cryptogams in which the woody zone separated a
medullary from a cortical portion[486].”
In 1879 Renault[487] expressed the opinion that Brongniart by his
investigation of the anatomy of Sigillaria elegans had established in a
manner “presque irréfutable” that Sigillaria must be classed as a
Gymnosperm showing affinity with the Cycads.
In 1855 Goldenberg[488] described some strobili which he regarded as
those of Sigillaria and recognised their close resemblance to a fertile plant
of Isoetes. He was led to the conclusion, which had little influence on
contemporary opinion, that Sigillaria is related to Isoetes and must be
classed among Pteridophytes. To these long and narrow strobili Schimper
may encircle the stem[482]. The zones are usually of uneven breadth, as in S.
Brardi, and their occurrence produces some deformation of the adjacent
leaf-scars.
By the earlier writers Sigillaria was compared with succulent
Euphorbias, Cacti, and Palms; Brongniart[483] at first included undoubted
Sigillarian stems among Ferns, but after investigating an agatized stem from
Autun, he referred Sigillaria to the Gymnosperms[484] on the ground that it
had the power of producing secondary wood. It was then supposed that
Lepidodendron possessed only primary xylem, and that the presence of a
vascular meristem in Sigillaria necessitated its separation from the
lycopodiaceous genus Lepidodendron and its inclusion in the higher plants.
By slow degrees it was recognised, as in the parallel case of the genus
Calamites, that the presence or absence of secondary vascular tissue is a
character of small importance. Williamson, whose anatomical researches
played the most important part in ridding the minds of palaeobotanists of
the superstition that secondary growth in thickness is a monopoly of the
Phanerogams, spoke in 1883 of the conflict as to the affinities of
Lepidodendron and Sigillaria as virtually over but leaving here and there
“the ground-swell of a stormy past[485].” In 1872 the same author had
written: “If then I am correct in thus bringing the Lepidodendra and
Sigillariae into such close affinity, there is an end of M. Brongniart’s theory,
that the latter were gymnospermous exogens, because the cryptogamic
character of the former is disputed by no one; we must rather conclude as I
have done that the entire series represents, along with the Calamites, an
exogenous group of Cryptogams in which the woody zone separated a
medullary from a cortical portion[486].”
In 1879 Renault[487] expressed the opinion that Brongniart by his
investigation of the anatomy of Sigillaria elegans had established in a
manner “presque irréfutable” that Sigillaria must be classed as a
Gymnosperm showing affinity with the Cycads.
In 1855 Goldenberg[488] described some strobili which he regarded as
those of Sigillaria and recognised their close resemblance to a fertile plant
of Isoetes. He was led to the conclusion, which had little influence on
contemporary opinion, that Sigillaria is related to Isoetes and must be
classed among Pteridophytes. To these long and narrow strobili Schimper
Page 243
gave the name Sigillariostrobus[489]. In 1884 Zeiller[490] supplied
confirmation of Goldenberg’s view by the discovery of cones borne on
pedicels with Sigillarian leaf-scars, thus demonstrating the generic identity
of cones and vegetative shoots, which Goldenberg had connected on the
evidence of association. Zeiller’s more recent work[491] and the still later
researches of Kidston[492] have added considerably to our knowledge of the
morphology of Sigillarian cones. Grand’Eury’s remark made so recently as
1890[493] that opinion in regard to the Gymnospermous nature of Sigillaria is
losing ground every day, bears striking testimony to the pertinacity with
which old beliefs linger even in the face of overwhelming proof of their
falsity.
It is remarkable, in view of the abundance of vegetative shoots, how
rarely undoubted Sigillarian strobili have been found; this may, however, be
in part due to a confusion with Lepidostrobi which so far as we know do not
differ in important respects from Sigillariostrobi[494].
There can be no doubt that Sigillaria usually produced its cones on
slender pedicels which bore a few leaves or bracts in irregular verticils, or
in short vertical series on comparatively stout stems, an arrangement
reminding us of the occurrence of flowers on old stems of Theobroma and
other recent Dicotyledons. As Renault[495] pointed out the fertile shoots are
axillary in origin.
Dr Kidston[496] is of opinion that certain species of Sigillaria bore cones
sessile on large vegetative shoots characterised by two opposite rows of
cup-like depressions like those in the Ulodendron form of Lepidodendron
Veltheimianum (fig. 157). He has described the Ulodendron condition of
two species, Sigillaria discophora (König) and S. Taylori (Carr.); the cup-
like depressions may have a diameter of several centimetres and are
distinguished from those of Bothrodendron by the almost central position of
the umbilicus. The specimens which he figures as S. discophora are
identified by him with the stem figured by König as Lepidodendron
discophorum and by Lindley and Hutton[497] as Ulodendron minus. We have
already dealt with the nature of Ulodendron shoots, expressing the opinion
that in spite of the often quoted specimen described by D’Arcy
Thompson[498], in which a supposed cone occurs in one of the cups, there is
no satisfactory case of any undoubted cone having been found attached to
the large Ulodendron scars. It is more probable that the Ulodendron
confirmation of Goldenberg’s view by the discovery of cones borne on
pedicels with Sigillarian leaf-scars, thus demonstrating the generic identity
of cones and vegetative shoots, which Goldenberg had connected on the
evidence of association. Zeiller’s more recent work[491] and the still later
researches of Kidston[492] have added considerably to our knowledge of the
morphology of Sigillarian cones. Grand’Eury’s remark made so recently as
1890[493] that opinion in regard to the Gymnospermous nature of Sigillaria is
losing ground every day, bears striking testimony to the pertinacity with
which old beliefs linger even in the face of overwhelming proof of their
falsity.
It is remarkable, in view of the abundance of vegetative shoots, how
rarely undoubted Sigillarian strobili have been found; this may, however, be
in part due to a confusion with Lepidostrobi which so far as we know do not
differ in important respects from Sigillariostrobi[494].
There can be no doubt that Sigillaria usually produced its cones on
slender pedicels which bore a few leaves or bracts in irregular verticils, or
in short vertical series on comparatively stout stems, an arrangement
reminding us of the occurrence of flowers on old stems of Theobroma and
other recent Dicotyledons. As Renault[495] pointed out the fertile shoots are
axillary in origin.
Dr Kidston[496] is of opinion that certain species of Sigillaria bore cones
sessile on large vegetative shoots characterised by two opposite rows of
cup-like depressions like those in the Ulodendron form of Lepidodendron
Veltheimianum (fig. 157). He has described the Ulodendron condition of
two species, Sigillaria discophora (König) and S. Taylori (Carr.); the cup-
like depressions may have a diameter of several centimetres and are
distinguished from those of Bothrodendron by the almost central position of
the umbilicus. The specimens which he figures as S. discophora are
identified by him with the stem figured by König as Lepidodendron
discophorum and by Lindley and Hutton[497] as Ulodendron minus. We have
already dealt with the nature of Ulodendron shoots, expressing the opinion
that in spite of the often quoted specimen described by D’Arcy
Thompson[498], in which a supposed cone occurs in one of the cups, there is
no satisfactory case of any undoubted cone having been found attached to
the large Ulodendron scars. It is more probable that the Ulodendron
Page 244
depressions represent the scars of branches, either elongated axes, or
possibly in some cases deciduous tuberous shoots which served as organs of
vegetative reproduction. A specimen figured by Kidston as Sigillaria
Taylori from the Calciferous sandstone of Scotland[499] bears a row of
slightly projecting “appendicular organs” attached to a Ulodendron axis; but
these furnish no proof of their strobiloid nature. The main question is, are
these Ulodendron shoots correctly identified by Kidston as Sigillarian? The
surface of the specimens shows crowded rhomboidal scars surrounded in
some cases by a very narrow border or cushion; the general appearance is,
as Kidston maintains, like that of Sigillaria Brardi in which the leaf-scars
are contiguous (e.g. fig. 203, upper part). None of the leaf-scars exhibit the
three characteristic features, the leaf-trace and parichnos scars, but only one
small scar appears on each leaf-base area. In a more recent paper Kidston
figures a small piece of a stem from Kilmarnock, which he identifies as
Sigillaria discophora, showing the three characteristic scars on the leaf-
base area. There is no doubt as to the Sigillarian nature of this specimen, but
it is not clear if the piece figured is part of a Ulodendron shoot[500].
Prof. Zeiller[501] retains the older name Ulodendron minus Lind. and Hutt.
in place of König’s specific designation and dissents from Kidston’s
identification of Ulodendron minus and U. majus of Lindley and Hutton as
one species; he is also inclined to refer these Ulodendron axes to
Lepidodendron. In spite of the superficial resemblance to Sigillaria of the
specimens described by Kidston, and which I have had an opportunity of
examining, I venture to regard their reference to that genus as by no means
definitely established. We must recognise the difficulty in certain cases of
drawing any satisfactory distinction between Sigillaria and Lepidodendron
based on external features, and while giving due weight to the conclusions
of so experienced a palaeobotanist as my friend Dr Kidston, I venture to
think we are not in a position to state with confidence that Sigillaria
possessed Ulodendron shoots.
ii. Leaves.
The leaves of Sigillaria agree closely with those of Lepidodendron; they
are either acicular (fig. 200, D) like Pine needles or broader and flatter like
the leaves of Podocarpus. Their attachment to comparatively thick
branches[502] shows that they persisted, in some cases at least, for several
possibly in some cases deciduous tuberous shoots which served as organs of
vegetative reproduction. A specimen figured by Kidston as Sigillaria
Taylori from the Calciferous sandstone of Scotland[499] bears a row of
slightly projecting “appendicular organs” attached to a Ulodendron axis; but
these furnish no proof of their strobiloid nature. The main question is, are
these Ulodendron shoots correctly identified by Kidston as Sigillarian? The
surface of the specimens shows crowded rhomboidal scars surrounded in
some cases by a very narrow border or cushion; the general appearance is,
as Kidston maintains, like that of Sigillaria Brardi in which the leaf-scars
are contiguous (e.g. fig. 203, upper part). None of the leaf-scars exhibit the
three characteristic features, the leaf-trace and parichnos scars, but only one
small scar appears on each leaf-base area. In a more recent paper Kidston
figures a small piece of a stem from Kilmarnock, which he identifies as
Sigillaria discophora, showing the three characteristic scars on the leaf-
base area. There is no doubt as to the Sigillarian nature of this specimen, but
it is not clear if the piece figured is part of a Ulodendron shoot[500].
Prof. Zeiller[501] retains the older name Ulodendron minus Lind. and Hutt.
in place of König’s specific designation and dissents from Kidston’s
identification of Ulodendron minus and U. majus of Lindley and Hutton as
one species; he is also inclined to refer these Ulodendron axes to
Lepidodendron. In spite of the superficial resemblance to Sigillaria of the
specimens described by Kidston, and which I have had an opportunity of
examining, I venture to regard their reference to that genus as by no means
definitely established. We must recognise the difficulty in certain cases of
drawing any satisfactory distinction between Sigillaria and Lepidodendron
based on external features, and while giving due weight to the conclusions
of so experienced a palaeobotanist as my friend Dr Kidston, I venture to
think we are not in a position to state with confidence that Sigillaria
possessed Ulodendron shoots.
ii. Leaves.
The leaves of Sigillaria agree closely with those of Lepidodendron; they
are either acicular (fig. 200, D) like Pine needles or broader and flatter like
the leaves of Podocarpus. Their attachment to comparatively thick
branches[502] shows that they persisted, in some cases at least, for several
Page 245
years as in Araucaria imbricata. The lower surface of the lamina was
characterised by a prominent keel (fig. 142, A and C) which dies out
towards the apex; on either side of it are well-defined stomatal grooves
(figs. 142, g, g; 143, A; 200, D, g). The upper face may be characterised by
another groove (fig. 142, B) but without stomata. The occurrence of the
stomatal grooves, the abundance of transfusion tracheae (fig. 142, t)
surrounding the vascular bundle, and the presence of strengthening
hypodermal tissue suggest that the leaves of Sigillaria were of a more or
less pronounced xerophilous type and had a fairly strong and leathery
lamina. The mesophyll tissue consists either of short parenchymatous cells
or of radially elongated palisade-like elements and has the loose or lacunar
arrangement characteristic of the aerating system in recent leaves; the slight
development or absence of palisade-tissue may indicate exposure to diffuse
light of no great intensity.
In most species there is a single vein, but in others the xylem forms a
double strand (fig. 142, B). Sections of the lamina near the apical region
present a more circular form, owing to the gradual obliteration of the upper
groove and lower keel and to the dying out of the stomatal grooves.
The transverse section of the leaf diagrammatically represented in fig.
142, A, A′, shows the two stomatal grooves, g, and a prominent keel; the
single vein consists of a small group of primary tracheae, x, some delicate
parenchyma, and a brown patch of imperfectly preserved tissues, a,
resembling the secretory zone tissue of a Lepidodendron. The whole is
surrounded by a sheath of rather wide and short thinner-walled spiral or
reticulate tracheids, which may be spoken of as transfusion tracheae, t, and
compared with similar elements in the leaves of many recent Conifers. To
this tissue Renault applies the epithet “water-bearing” and it is very likely
that this may have been its function. The shaded portions of the lamina, in
fig. 142, A, represent the distribution of thicker-walled hypodermal tissue.
The section of a leaf 3 mm. wide shown in fig. 142, C, shows an almost
identical structure; the transfusion tracheae are richly developed especially
on the sides and lower surface of the vascular strand. This leaf occurs in
association with a petrified stem of Sigillaria scutellata[503].
characterised by a prominent keel (fig. 142, A and C) which dies out
towards the apex; on either side of it are well-defined stomatal grooves
(figs. 142, g, g; 143, A; 200, D, g). The upper face may be characterised by
another groove (fig. 142, B) but without stomata. The occurrence of the
stomatal grooves, the abundance of transfusion tracheae (fig. 142, t)
surrounding the vascular bundle, and the presence of strengthening
hypodermal tissue suggest that the leaves of Sigillaria were of a more or
less pronounced xerophilous type and had a fairly strong and leathery
lamina. The mesophyll tissue consists either of short parenchymatous cells
or of radially elongated palisade-like elements and has the loose or lacunar
arrangement characteristic of the aerating system in recent leaves; the slight
development or absence of palisade-tissue may indicate exposure to diffuse
light of no great intensity.
In most species there is a single vein, but in others the xylem forms a
double strand (fig. 142, B). Sections of the lamina near the apical region
present a more circular form, owing to the gradual obliteration of the upper
groove and lower keel and to the dying out of the stomatal grooves.
The transverse section of the leaf diagrammatically represented in fig.
142, A, A′, shows the two stomatal grooves, g, and a prominent keel; the
single vein consists of a small group of primary tracheae, x, some delicate
parenchyma, and a brown patch of imperfectly preserved tissues, a,
resembling the secretory zone tissue of a Lepidodendron. The whole is
surrounded by a sheath of rather wide and short thinner-walled spiral or
reticulate tracheids, which may be spoken of as transfusion tracheae, t, and
compared with similar elements in the leaves of many recent Conifers. To
this tissue Renault applies the epithet “water-bearing” and it is very likely
that this may have been its function. The shaded portions of the lamina, in
fig. 142, A, represent the distribution of thicker-walled hypodermal tissue.
The section of a leaf 3 mm. wide shown in fig. 142, C, shows an almost
identical structure; the transfusion tracheae are richly developed especially
on the sides and lower surface of the vascular strand. This leaf occurs in
association with a petrified stem of Sigillaria scutellata[503].
Page 246
Fig. 200.
A. Sigillaria Brardi [= S. elegans Brongn. (39)]. Transverse section of stem.
B. Sigillaria Brardi [= S. spinulosa, Renault and Grand’Eury (75)]: c3, outer cortex;
x, x2, xylem. (After Renault and Grand’Eury.)
C. S. Brardi, primary xylem element. (A and C after Brongniart.)
D. Leaf of Sigillaria Brardi: g, g, stomatal grooves; ep, piece of epidermis of stem.
(After Renault.)
E. Sigillaria Brardi. Tangential section of leaf-bases: p, parichnos. (After Renault.)
F, G, H. Sigillaria leaf-scars and cushions. (After Weiss.)
Renault[504] has shown that the leaf-traces of Sigillaria spinulosa (= S.
Brardi) are accompanied in the outer cortical region of the stem by a fairly
large amount of secondary xylem; in sections of the free lamina which he
figures the secondary elements are much less obvious and represented by a
few tracheae only. Similarly, in the leaf-base of S. Brardi (fig. 200, E) the
xylem consists of both primary and secondary elements (x, x2), but in the
lamina the latter is poorly if at all represented. In the lamina of the leaves of
S. Brardi the primary xylem forms a narrow slightly curved band with two
lateral groups of narrower, presumably protoxylem elements; this is
A. Sigillaria Brardi [= S. elegans Brongn. (39)]. Transverse section of stem.
B. Sigillaria Brardi [= S. spinulosa, Renault and Grand’Eury (75)]: c3, outer cortex;
x, x2, xylem. (After Renault and Grand’Eury.)
C. S. Brardi, primary xylem element. (A and C after Brongniart.)
D. Leaf of Sigillaria Brardi: g, g, stomatal grooves; ep, piece of epidermis of stem.
(After Renault.)
E. Sigillaria Brardi. Tangential section of leaf-bases: p, parichnos. (After Renault.)
F, G, H. Sigillaria leaf-scars and cushions. (After Weiss.)
Renault[504] has shown that the leaf-traces of Sigillaria spinulosa (= S.
Brardi) are accompanied in the outer cortical region of the stem by a fairly
large amount of secondary xylem; in sections of the free lamina which he
figures the secondary elements are much less obvious and represented by a
few tracheae only. Similarly, in the leaf-base of S. Brardi (fig. 200, E) the
xylem consists of both primary and secondary elements (x, x2), but in the
lamina the latter is poorly if at all represented. In the lamina of the leaves of
S. Brardi the primary xylem forms a narrow slightly curved band with two
lateral groups of narrower, presumably protoxylem elements; this is
Page 247
surrounded by delicate parenchyma styled by Renault, on very slender
evidence, phloem (“liber”). Some dark cells below the xylem are described
as sclerous tissue, and surrounding the bundle is a sheath of transfusion
tracheae (dotted area in fig. 200, E). It is possible that the elements spoken
of with hesitation by Renault as secondary xylem are transfusion tracheae.
There has probably been some confusion in the minds of authors between
sclerous tissue and dark secretory tissue in Sigillarian leaves; the crescentic
band, a, shown in fig. 142, B, which corresponds in position with the
sclerous tissue of Renault in S. Brardi leaves, appears to be of the nature of
secretory tissue.
The diagram shown in fig. 142, B, illustrates a type of leaf very like those
already described, except that there are two xylem strands, x. The difference
between the double strand and the single bundle seen in figs. 142, A, C and
200 E, is comparatively small, but it is a real distinction. This type of leaf
(fig. 142, B) was originally described by Renault[505] under the generic title
Sigillariopsis. The genus was founded on a French petrified specimen
consisting of part of a ribbed stem possessing a stele of the Sigillarian type
and characterised by separate primary xylem strands, like those of S. Brardi
described by Brongniart in 1839. Renault considered the presence of two
xylem strands in the leaf a sufficient reason for the institution of a new
genus and named the specimen Sigillariopsis Decaisnei. Prof. Bertrand of
Lille kindly photographed for me Renault’s type-specimen and sent several
prints with explanatory notes. The transverse section of the leaves shows
very clearly the two xylem strands; each strand consists of a triangular
group of primary tracheae with the protoxylem apex pointing towards the
lower surface of the lamina. Below each primary strand of centripetal
xylem is an arc composed of a few small tracheae which Renault and
Bertrand describe as secondary xylem; it is, however, not clear from the
photomicrographs that these are of secondary origin, their position and
appearance reminding one of the primary centrifugal xylem of a cycadean
foliar bundle. Below this centrifugal xylem is another arc of imperfectly
preserved elements described by Renault as a protective sheath and by
Bertrand as glandular tissue; the latter term is probably the more correct as
the tissue may well correspond to the secretory-zone tissue of
Lepidodendron stems. Fairly large groups of transfusion tracheids occur on
the flanks of the xylem. Prof. Bertrand points out that one of his sections,
evidence, phloem (“liber”). Some dark cells below the xylem are described
as sclerous tissue, and surrounding the bundle is a sheath of transfusion
tracheae (dotted area in fig. 200, E). It is possible that the elements spoken
of with hesitation by Renault as secondary xylem are transfusion tracheae.
There has probably been some confusion in the minds of authors between
sclerous tissue and dark secretory tissue in Sigillarian leaves; the crescentic
band, a, shown in fig. 142, B, which corresponds in position with the
sclerous tissue of Renault in S. Brardi leaves, appears to be of the nature of
secretory tissue.
The diagram shown in fig. 142, B, illustrates a type of leaf very like those
already described, except that there are two xylem strands, x. The difference
between the double strand and the single bundle seen in figs. 142, A, C and
200 E, is comparatively small, but it is a real distinction. This type of leaf
(fig. 142, B) was originally described by Renault[505] under the generic title
Sigillariopsis. The genus was founded on a French petrified specimen
consisting of part of a ribbed stem possessing a stele of the Sigillarian type
and characterised by separate primary xylem strands, like those of S. Brardi
described by Brongniart in 1839. Renault considered the presence of two
xylem strands in the leaf a sufficient reason for the institution of a new
genus and named the specimen Sigillariopsis Decaisnei. Prof. Bertrand of
Lille kindly photographed for me Renault’s type-specimen and sent several
prints with explanatory notes. The transverse section of the leaves shows
very clearly the two xylem strands; each strand consists of a triangular
group of primary tracheae with the protoxylem apex pointing towards the
lower surface of the lamina. Below each primary strand of centripetal
xylem is an arc composed of a few small tracheae which Renault and
Bertrand describe as secondary xylem; it is, however, not clear from the
photomicrographs that these are of secondary origin, their position and
appearance reminding one of the primary centrifugal xylem of a cycadean
foliar bundle. Below this centrifugal xylem is another arc of imperfectly
preserved elements described by Renault as a protective sheath and by
Bertrand as glandular tissue; the latter term is probably the more correct as
the tissue may well correspond to the secretory-zone tissue of
Lepidodendron stems. Fairly large groups of transfusion tracheids occur on
the flanks of the xylem. Prof. Bertrand points out that one of his sections,
Page 248
cut nearer the apex of a leaf than that figured by Renault with a single
xylem strand, contains a double strand and thus shows the latter’s
description to be an incorrect interpretation of the imperfectly preserved
tissues.
The Sigillariopsis type of leaf was recognised by Scott[506] in English
material on which he founded the species Sigillariopsis sulcata. In a section
which he has recently figured[507] a lacuna below the two xylem strands is
described as “representing secretory tissue”; a band of transfusion tracheae
almost encircles the pair of bundles.
In a note published in 1907, Kidston[508] demonstrated the association of
Sigillariopsis leaves with an undoubted Sigillarian stem of the Rhytidolepis
type and expressed his conviction that Renault’s genus is identical with
Sigillaria. The correctness of Kidston’s conclusion has been proved by
Arber and Thomas[509] who found that the leaf-traces of Sigillaria scutellata
bifurcate during their course through the outer region of the cortex and
enter the leaf as two distinct strands of primary xylem. In the section from
Dr Kidston’s collection shown in fig. 142, B, the lamina, 4 mm. wide,
consists mainly of thin-walled assimilating tissue composed of radially
elongated cells abutting at the periphery on hypodermal mechanical tissue,
except at the edges of the stomatal grooves which are bounded by the small-
celled epidermis. A broad sheath of thicker-walled elements, s, surrounds
numerous scattered transfusion tracheae, t, and below the two xylem
strands, x, which are embedded in delicate parenchyma there is a crescentic
band of dark tissue, a, resembling the smaller strand, a, in fig. 142, A′, and
the secretory zone tissue of a Lepidodendron stem.
iii. Fertile shoots of Sigillaria.
Reference has already been made to the manner of occurrence of strobili
on Sigillarian stems; it remains to describe the structure of these
reproductive shoots. Sigillariostrobus, the name given to Sigillarian strobili,
may be defined in general terms as follows:
Cylindrical cones, rarely dichotomously branched[510] as in species of
Lycopodium and Selaginella, which may reach a length of 30 cm. (e.g.
Sigillariostrobus nobilis Zeill.[511]) and a diameter 2–5 cm.; peduncle long
and slender, sometimes bearing acicular bracts or, after leaf-fall,
xylem strand, contains a double strand and thus shows the latter’s
description to be an incorrect interpretation of the imperfectly preserved
tissues.
The Sigillariopsis type of leaf was recognised by Scott[506] in English
material on which he founded the species Sigillariopsis sulcata. In a section
which he has recently figured[507] a lacuna below the two xylem strands is
described as “representing secretory tissue”; a band of transfusion tracheae
almost encircles the pair of bundles.
In a note published in 1907, Kidston[508] demonstrated the association of
Sigillariopsis leaves with an undoubted Sigillarian stem of the Rhytidolepis
type and expressed his conviction that Renault’s genus is identical with
Sigillaria. The correctness of Kidston’s conclusion has been proved by
Arber and Thomas[509] who found that the leaf-traces of Sigillaria scutellata
bifurcate during their course through the outer region of the cortex and
enter the leaf as two distinct strands of primary xylem. In the section from
Dr Kidston’s collection shown in fig. 142, B, the lamina, 4 mm. wide,
consists mainly of thin-walled assimilating tissue composed of radially
elongated cells abutting at the periphery on hypodermal mechanical tissue,
except at the edges of the stomatal grooves which are bounded by the small-
celled epidermis. A broad sheath of thicker-walled elements, s, surrounds
numerous scattered transfusion tracheae, t, and below the two xylem
strands, x, which are embedded in delicate parenchyma there is a crescentic
band of dark tissue, a, resembling the smaller strand, a, in fig. 142, A′, and
the secretory zone tissue of a Lepidodendron stem.
iii. Fertile shoots of Sigillaria.
Reference has already been made to the manner of occurrence of strobili
on Sigillarian stems; it remains to describe the structure of these
reproductive shoots. Sigillariostrobus, the name given to Sigillarian strobili,
may be defined in general terms as follows:
Cylindrical cones, rarely dichotomously branched[510] as in species of
Lycopodium and Selaginella, which may reach a length of 30 cm. (e.g.
Sigillariostrobus nobilis Zeill.[511]) and a diameter 2–5 cm.; peduncle long
and slender, sometimes bearing acicular bracts or, after leaf-fall,
Page 249
characterised by leaf-cushions and leaf-scars like those on vegetative shoots
(fig. 201, E). The stalked cones are borne in irregular verticils and in some
species in vertical series, the fertile zones being separated by comparatively
long sterile portions of the stem (fig. 199). The cones were deciduous and,
in certain cases if not in all, the individual sporophylls became detached
from the cone-axis on maturity. The slender axis bore spiral or verticillate
imbricate sporophylls attached at right angles or more or less obliquely. The
basal rhomboidal portion bore spores on its upper surface (fig. 201, F),
presumably enclosed in a somewhat radially elongated sporangium (fig. B)
and was prolonged distally into a narrow lanceolate free portion, in some
species with a ciliate border (fig. D). The sporangia probably produced
megaspores and microspores, but such spores as have been recognised
appear to belong to the former category. The designation Triletes is applied
to isolated spores of Sigillaria or to those of Lepidodendron.
Sigillariostrobus Tieghemi Zeiller[512] (figs. 201, E, F). In this species,
from the Coal-field of Valenciennes, the pedicel bore acicular leaves or
bracts attached to the upper portion of leaf-cushions arranged in vertical
series (fig. E). The cones reached a length of 16 cm. and a breadth of 2·5–5
cm.; the sporophylls are borne in alternating verticils with 8–10 in each
whorl. Several megaspores (2 mm. in diameter) appear to have been
produced in tetrads in each sporangium.
(fig. 201, E). The stalked cones are borne in irregular verticils and in some
species in vertical series, the fertile zones being separated by comparatively
long sterile portions of the stem (fig. 199). The cones were deciduous and,
in certain cases if not in all, the individual sporophylls became detached
from the cone-axis on maturity. The slender axis bore spiral or verticillate
imbricate sporophylls attached at right angles or more or less obliquely. The
basal rhomboidal portion bore spores on its upper surface (fig. 201, F),
presumably enclosed in a somewhat radially elongated sporangium (fig. B)
and was prolonged distally into a narrow lanceolate free portion, in some
species with a ciliate border (fig. D). The sporangia probably produced
megaspores and microspores, but such spores as have been recognised
appear to belong to the former category. The designation Triletes is applied
to isolated spores of Sigillaria or to those of Lepidodendron.
Sigillariostrobus Tieghemi Zeiller[512] (figs. 201, E, F). In this species,
from the Coal-field of Valenciennes, the pedicel bore acicular leaves or
bracts attached to the upper portion of leaf-cushions arranged in vertical
series (fig. E). The cones reached a length of 16 cm. and a breadth of 2·5–5
cm.; the sporophylls are borne in alternating verticils with 8–10 in each
whorl. Several megaspores (2 mm. in diameter) appear to have been
produced in tetrads in each sporangium.
Page 250
Fig. 201. Sigillariostrobus.
A, C. Sigillariostrobus rhombibracteatus Kidst. (After Kidston.)
A. Portion of strobilus.
C. Megaspore.
B, D. Sigillariostrobus ciliatus Kidst. (After Kidston.)
E, F. Sigillariostrobus Tieghemi Zeill. (After Zeiller.)
Sigillariostrobus rhombibracteatus Kidston[513]. Fig. 201, A, C.
Kidston described this species from the Middle Coal-Measures of
England: it is similar in habit and in the form of the sporophylls to S.
Tieghemi, but rather smaller, and the more definitely rhomboidal
sporophylls have a ciliate margin. The cone was probably heterosporous,
but megaspores alone have so far been discovered. The sporophylls bear a
close resemblance to those of Lycopodium cernuum (fig. 126, C). In some
of the illustrations of this type given by Kidston the naked cone-axis with
its numerous sporophyll-scars is clearly shown, reminding one of the naked
axes of the cones of the Silver Fir (Abies pectinata) or Cedar after the fall of
the scales.
A, C. Sigillariostrobus rhombibracteatus Kidst. (After Kidston.)
A. Portion of strobilus.
C. Megaspore.
B, D. Sigillariostrobus ciliatus Kidst. (After Kidston.)
E, F. Sigillariostrobus Tieghemi Zeill. (After Zeiller.)
Sigillariostrobus rhombibracteatus Kidston[513]. Fig. 201, A, C.
Kidston described this species from the Middle Coal-Measures of
England: it is similar in habit and in the form of the sporophylls to S.
Tieghemi, but rather smaller, and the more definitely rhomboidal
sporophylls have a ciliate margin. The cone was probably heterosporous,
but megaspores alone have so far been discovered. The sporophylls bear a
close resemblance to those of Lycopodium cernuum (fig. 126, C). In some
of the illustrations of this type given by Kidston the naked cone-axis with
its numerous sporophyll-scars is clearly shown, reminding one of the naked
axes of the cones of the Silver Fir (Abies pectinata) or Cedar after the fall of
the scales.
Page 251
Our knowledge of Sigillarian cones is too incomplete to admit of a
detailed comparison with the strobili of Lepidodendron or with those of
recent Pteridophytes. There can, however, be little doubt that
Goldenberg[514] was correct in his selection of Isoetes as the most nearly
allied recent plant so far as the fertile leaves are concerned. It would seem
that the sporangia were comparatively delicate structures which have left no
clearly defined remains of their walls in the carbonised specimens; Kidston,
indeed, speaks of the hollow bases of the sporophylls as holding the spores,
but this is hardly likely to have been the case. Our knowledge of the
anatomy of Sigillariostrobus is practically nil, but in one specimen of a
Sigillaria elegans stem Kidston[515] describes the structure of the tissues as
seen in a transverse section of a scar of a fertile shoot; from this we learn
that the stele was composed exclusively of primary tracheids forming a
solid strand without a pith. It is probable that the cones of Sigillaria were
heterosporous, but in no instance have undoubted microspores been
discovered; the megaspores in each megasporangium were fairly numerous
as in Isoetes (fig. 133, E). In one species, Sigillariostrobus major (Germar),
from Permian rocks of France and Germany, Zeiller[516] states that the whole
of a single cone bore megaspores (0·8–1 mm. in diameter) only; this is,
however, not opposed to the idea of heterospory, as we find instances in
Selaginella of strobili bearing one kind of spore only (cf. p. 56).
In a few instances, it has been possible to correlate cones with certain
species of Sigillaria, but in most cases the strobili occur as isolated fossils.
iv. The structure of Sigillarian stems.
The first account of the anatomy of Sigillaria we owe to Brongniart[517]
who published a description of the internal structure of an agatised stem,
about 4 cm. in diameter, from Autun, which he referred to Sigillaria
elegans. It has, however, been shown by Zeiller[518] and by Renault that this
petrified fragment belongs to Brongniart’s species S. Menardi, which is
probably a young form of S. Brardi. Brongniart’s specimen, now preserved
in the Paris Natural History Museum, is a very beautiful example of a
silicified plant: on part of the surface are preserved the hexagonal
contiguous leaf-scars, like those shown in fig. 193, A, and on the polished
transverse section is seen a relatively large stele consisting of a ring of
secondary xylem surrounding a series of crescentic groups of primary
detailed comparison with the strobili of Lepidodendron or with those of
recent Pteridophytes. There can, however, be little doubt that
Goldenberg[514] was correct in his selection of Isoetes as the most nearly
allied recent plant so far as the fertile leaves are concerned. It would seem
that the sporangia were comparatively delicate structures which have left no
clearly defined remains of their walls in the carbonised specimens; Kidston,
indeed, speaks of the hollow bases of the sporophylls as holding the spores,
but this is hardly likely to have been the case. Our knowledge of the
anatomy of Sigillariostrobus is practically nil, but in one specimen of a
Sigillaria elegans stem Kidston[515] describes the structure of the tissues as
seen in a transverse section of a scar of a fertile shoot; from this we learn
that the stele was composed exclusively of primary tracheids forming a
solid strand without a pith. It is probable that the cones of Sigillaria were
heterosporous, but in no instance have undoubted microspores been
discovered; the megaspores in each megasporangium were fairly numerous
as in Isoetes (fig. 133, E). In one species, Sigillariostrobus major (Germar),
from Permian rocks of France and Germany, Zeiller[516] states that the whole
of a single cone bore megaspores (0·8–1 mm. in diameter) only; this is,
however, not opposed to the idea of heterospory, as we find instances in
Selaginella of strobili bearing one kind of spore only (cf. p. 56).
In a few instances, it has been possible to correlate cones with certain
species of Sigillaria, but in most cases the strobili occur as isolated fossils.
iv. The structure of Sigillarian stems.
The first account of the anatomy of Sigillaria we owe to Brongniart[517]
who published a description of the internal structure of an agatised stem,
about 4 cm. in diameter, from Autun, which he referred to Sigillaria
elegans. It has, however, been shown by Zeiller[518] and by Renault that this
petrified fragment belongs to Brongniart’s species S. Menardi, which is
probably a young form of S. Brardi. Brongniart’s specimen, now preserved
in the Paris Natural History Museum, is a very beautiful example of a
silicified plant: on part of the surface are preserved the hexagonal
contiguous leaf-scars, like those shown in fig. 193, A, and on the polished
transverse section is seen a relatively large stele consisting of a ring of
secondary xylem surrounding a series of crescentic groups of primary
Page 252
xylem (fig. 200, A) enclosing a wide pith occupied by concentric layers of
silica. A portion of the outer cortex is preserved, and this is separated from
the stele by a broad space filled with siliceous rock. The main features of
this type may be described in a few words. The primary xylem differs from
that of such Lepidodendron stems as have been described in being made up
of groups of scalariform and occasionally reticulate (fig. 200, C) tracheae,
having a plano-convex or more or less crescentic form as seen in transverse
section. These primary strands, in contact with one another laterally, have
their narrowest elements on the outer edge. The leaf-traces are given off
from the middle of the abaxial face of each xylem strand (fig. 202, C, lt);
these pass obliquely outwards through medullary rays and then, as in
Lepidodendron, turn sharply upwards before bending outwards again on
their way to the leaves. Each leaf-trace consists of a group of primary
tracheae to which a few secondary tracheae are added during the passage
through the secondary wood. The secondary xylem forms a continuous
cylinder of tracheae with scalariform bands on both radial and tangential
walls; the medullary rays are numerous and consist of long and narrow
series, usually one cell broad, of parenchymatous cells with occasional
short rays one or more cells in depth.
The slightly greater breadth of the rays between each primary xylem
strand tends to divide the secondary wood into bundles corresponding in
breadth to the primary groups. The outer cortex closely resembles that of
Lepidodendron; it consists internally of radial series of secondary, elongated
and rather stout, elements abutting on the parenchymatous tissue of the leaf-
cushions.
The next contribution to our knowledge of the anatomy of Sigillaria was
made by Renault and Grand’Eury[519] who described the structure of
Sigillaria spinulosa Germar[520], a species now recognised as the
Leiodermarian condition of S. Brardi, and probably, therefore, not specially
distinct from the specimen described by Brongniart in 1839 as S. elegans.
In Brongniart’s fossil the leaf-cushions are in contact (Clathrarian form of
S. Brardi: fig. 203, upper part) whereas in the specimen now under
consideration the leaf-scars are further apart (Leiodermarian form of S.
Brardi, fig. 203, lower part, and fig. 196, C). It may be, as Scott suggests,
that these two specimens are not specifically identical but closely allied, an
silica. A portion of the outer cortex is preserved, and this is separated from
the stele by a broad space filled with siliceous rock. The main features of
this type may be described in a few words. The primary xylem differs from
that of such Lepidodendron stems as have been described in being made up
of groups of scalariform and occasionally reticulate (fig. 200, C) tracheae,
having a plano-convex or more or less crescentic form as seen in transverse
section. These primary strands, in contact with one another laterally, have
their narrowest elements on the outer edge. The leaf-traces are given off
from the middle of the abaxial face of each xylem strand (fig. 202, C, lt);
these pass obliquely outwards through medullary rays and then, as in
Lepidodendron, turn sharply upwards before bending outwards again on
their way to the leaves. Each leaf-trace consists of a group of primary
tracheae to which a few secondary tracheae are added during the passage
through the secondary wood. The secondary xylem forms a continuous
cylinder of tracheae with scalariform bands on both radial and tangential
walls; the medullary rays are numerous and consist of long and narrow
series, usually one cell broad, of parenchymatous cells with occasional
short rays one or more cells in depth.
The slightly greater breadth of the rays between each primary xylem
strand tends to divide the secondary wood into bundles corresponding in
breadth to the primary groups. The outer cortex closely resembles that of
Lepidodendron; it consists internally of radial series of secondary, elongated
and rather stout, elements abutting on the parenchymatous tissue of the leaf-
cushions.
The next contribution to our knowledge of the anatomy of Sigillaria was
made by Renault and Grand’Eury[519] who described the structure of
Sigillaria spinulosa Germar[520], a species now recognised as the
Leiodermarian condition of S. Brardi, and probably, therefore, not specially
distinct from the specimen described by Brongniart in 1839 as S. elegans.
In Brongniart’s fossil the leaf-cushions are in contact (Clathrarian form of
S. Brardi: fig. 203, upper part) whereas in the specimen now under
consideration the leaf-scars are further apart (Leiodermarian form of S.
Brardi, fig. 203, lower part, and fig. 196, C). It may be, as Scott suggests,
that these two specimens are not specifically identical but closely allied, an
Page 253
opinion based on certain anatomical differences[521]; we may, however,
include both under the comprehensive name S. Brardi.
The primary xylem (fig. 200, B, x), is in some regions separated into
distinct strands, in others it forms a continuous band equal in length to
several of the separate groups. This type of stele, in which the primary
xylem consists in part of separate strands and in part of a continuous
cylinder, forms a transition between that represented in fig. 200, A, and the
steles of Sigillaria elegans (fig. 202, A) and most species of Lepidodendron.
The tendency of the primary xylem strands to become united laterally,
forming broader bands, was first described by Solms-Laubach[522] in a
French specimen of Sigillaria spinulosa in the Williamson collection. The
leaf-traces arise from the middle of the concave outer face of the primary
xylem groups. The inner cortex is composed of small parenchymatous cells
as in Lepidodendron, and it is noteworthy that traces of partially
disorganised tissue, described as large canals, in the region external to the
secondary wood, bear a resemblance[523] to the secretory tissue of
Lepidodendron.
Other interesting features are presented by the structure of the outer
cortex and the parichnos. The outer cortex in the leaf-scar region is
composed of parenchyma, but for the most part it consists of radially
elongated groups of thin-walled parenchyma enclosed in a framework of
thicker-walled and elongated elements (fig. 200, B, c3). This type of cortex,
to which Brongniart applied the name Dictyoxylon, would produce a cast in
the case of a partially decorticated stem characterised by a surface formed
of irregularly oval and raised areas bounded by narrow grooves; the greater
prominence of the former being due to the more rapid decay of the softer
tissue, which would produce depressions on the exposed face of the dead
stem. Casts of this type are not uncommon in Carboniferous rocks, and
while some may belong to the Pteridosperm Lyginodendron, others may be
those of Sigillarian stems.
include both under the comprehensive name S. Brardi.
The primary xylem (fig. 200, B, x), is in some regions separated into
distinct strands, in others it forms a continuous band equal in length to
several of the separate groups. This type of stele, in which the primary
xylem consists in part of separate strands and in part of a continuous
cylinder, forms a transition between that represented in fig. 200, A, and the
steles of Sigillaria elegans (fig. 202, A) and most species of Lepidodendron.
The tendency of the primary xylem strands to become united laterally,
forming broader bands, was first described by Solms-Laubach[522] in a
French specimen of Sigillaria spinulosa in the Williamson collection. The
leaf-traces arise from the middle of the concave outer face of the primary
xylem groups. The inner cortex is composed of small parenchymatous cells
as in Lepidodendron, and it is noteworthy that traces of partially
disorganised tissue, described as large canals, in the region external to the
secondary wood, bear a resemblance[523] to the secretory tissue of
Lepidodendron.
Other interesting features are presented by the structure of the outer
cortex and the parichnos. The outer cortex in the leaf-scar region is
composed of parenchyma, but for the most part it consists of radially
elongated groups of thin-walled parenchyma enclosed in a framework of
thicker-walled and elongated elements (fig. 200, B, c3). This type of cortex,
to which Brongniart applied the name Dictyoxylon, would produce a cast in
the case of a partially decorticated stem characterised by a surface formed
of irregularly oval and raised areas bounded by narrow grooves; the greater
prominence of the former being due to the more rapid decay of the softer
tissue, which would produce depressions on the exposed face of the dead
stem. Casts of this type are not uncommon in Carboniferous rocks, and
while some may belong to the Pteridosperm Lyginodendron, others may be
those of Sigillarian stems.
Page 254
Fig. 202.
A. Sigillaria elegans Brongn. (Section in Dr Kidston’s Collection cut from the specimen
shown in fig. 193, D.)
B, C. Sigillaria elongata Brongn. lt, leaf-trace. (From specimens in the collection of Prof.
Bertrand.)
The large parichnos-strands, produced as in Lepidodendron, by the
forking of a single strand arising in the middle cortical region, consist in
part of tissue containing secretory canals, a structure like that recently
described by Miss Coward[524] in the large parichnos strands of
Syringodendron stems.
An example of a decorticated specimen is described by Renault[525] as
Sigillaria xylina. This stem is presumably referred to Sigillaria because the
primary xylem consists of separate strands. It is characterised by the
unusually large development of secondary wood and by the relatively small
size of the pith. The xylem cylinder has a diameter of 4–5 cm. and the pith
is only 4–5 mm. in breadth.
Another example of a petrified Sigillaria stem has been described by
Kidston[526] as S. elegans Brongn.[527] (fig. 193, D), a species characterised
A. Sigillaria elegans Brongn. (Section in Dr Kidston’s Collection cut from the specimen
shown in fig. 193, D.)
B, C. Sigillaria elongata Brongn. lt, leaf-trace. (From specimens in the collection of Prof.
Bertrand.)
The large parichnos-strands, produced as in Lepidodendron, by the
forking of a single strand arising in the middle cortical region, consist in
part of tissue containing secretory canals, a structure like that recently
described by Miss Coward[524] in the large parichnos strands of
Syringodendron stems.
An example of a decorticated specimen is described by Renault[525] as
Sigillaria xylina. This stem is presumably referred to Sigillaria because the
primary xylem consists of separate strands. It is characterised by the
unusually large development of secondary wood and by the relatively small
size of the pith. The xylem cylinder has a diameter of 4–5 cm. and the pith
is only 4–5 mm. in breadth.
Another example of a petrified Sigillaria stem has been described by
Kidston[526] as S. elegans Brongn.[527] (fig. 193, D), a species characterised
Page 255
by vertical rows of sub-hexagonal and contiguous leaf-scars and by the
presence of verticils of cone-scars. Fig. 193, D, represents Kidston’s
specimen in surface-view; one row of leaf-scars is shown, but most of the
superficial tissues have been destroyed. The crushed stele, 13 mm. in its
longest diameter, has a continuous cylinder of primary xylem, (fig. 202, A,
x) characterised by a regularly crenulate outer margin with the smallest
elements at the edge; the prominent ridges separating the sinuses are
rounded. The leaf-traces arise from the bottom of each sinus; the leaf-
bundles are mesarch, and consist exclusively of primary elements. The
secondary xylem, x2, like that of the primary xylem, has a crenulate outer
edge. The most interesting feature of the outer cortex is afforded by a
tangential section which, in addition to the leaf-scars, cuts through a cone-
scar showing a solid primary stele surrounded by the cortex of the cone-
peduncle.
Another type of Sigillaria, probably S. elongata Brongn. (fig. 202, B, C),
which is very similar to S. scutellata has been briefly described by Prof.
Bertrand[528], to whom my thanks are due for the two photographs
reproduced in fig. 202, B., C. His specimen, from the Pas de Calais Coal-
field, shows a ribbed Rhytidolepis form of surface (fig. 202, B). The stele
(fig. 202, C) agrees closely with that of S. elegans as described by Kidston,
but the ridges on the fluted surface of the primary xylem are more pointed.
“In the immediate neighbourhood of the origin of a leaf-trace, the spiral
elements form a median band in the middle of a sinus” and from this the
leaf-traces are given off. No secondary xylem was found in the leaf-traces
at any part of their course.
Bertrand compares the stele of S. elongata with that of the type of
Lepidodendron represented by the Burntisland species named by
Williamson L. brevifolium (fig. 186) and now usually referred to L.
Veltheimianum; the chief distinguishing features are the greater prominence
in the French species of the surface-ridges or teeth of the primary xylem, a
feature which occurs in L. Wünschianum, and the detachment of the leaf-
traces from the bottom of each sinus (fig. 202, C, lt) instead of from the
sides of the sinus. It is, however, not clear how far this latter distinction is a
real one; in Lepidodendron Wünschianum the leaf-traces appear to arise, as
in Sigillaria, from the middle of each sinus.
presence of verticils of cone-scars. Fig. 193, D, represents Kidston’s
specimen in surface-view; one row of leaf-scars is shown, but most of the
superficial tissues have been destroyed. The crushed stele, 13 mm. in its
longest diameter, has a continuous cylinder of primary xylem, (fig. 202, A,
x) characterised by a regularly crenulate outer margin with the smallest
elements at the edge; the prominent ridges separating the sinuses are
rounded. The leaf-traces arise from the bottom of each sinus; the leaf-
bundles are mesarch, and consist exclusively of primary elements. The
secondary xylem, x2, like that of the primary xylem, has a crenulate outer
edge. The most interesting feature of the outer cortex is afforded by a
tangential section which, in addition to the leaf-scars, cuts through a cone-
scar showing a solid primary stele surrounded by the cortex of the cone-
peduncle.
Another type of Sigillaria, probably S. elongata Brongn. (fig. 202, B, C),
which is very similar to S. scutellata has been briefly described by Prof.
Bertrand[528], to whom my thanks are due for the two photographs
reproduced in fig. 202, B., C. His specimen, from the Pas de Calais Coal-
field, shows a ribbed Rhytidolepis form of surface (fig. 202, B). The stele
(fig. 202, C) agrees closely with that of S. elegans as described by Kidston,
but the ridges on the fluted surface of the primary xylem are more pointed.
“In the immediate neighbourhood of the origin of a leaf-trace, the spiral
elements form a median band in the middle of a sinus” and from this the
leaf-traces are given off. No secondary xylem was found in the leaf-traces
at any part of their course.
Bertrand compares the stele of S. elongata with that of the type of
Lepidodendron represented by the Burntisland species named by
Williamson L. brevifolium (fig. 186) and now usually referred to L.
Veltheimianum; the chief distinguishing features are the greater prominence
in the French species of the surface-ridges or teeth of the primary xylem, a
feature which occurs in L. Wünschianum, and the detachment of the leaf-
traces from the bottom of each sinus (fig. 202, C, lt) instead of from the
sides of the sinus. It is, however, not clear how far this latter distinction is a
real one; in Lepidodendron Wünschianum the leaf-traces appear to arise, as
in Sigillaria, from the middle of each sinus.
Page 256
Other types of ribbed Sigillaria stems have been briefly described by
Scott[529], Kidston[530], and more recently, by Arber and Thomas[531].
The specimen described by Scott agrees in the main with S. elegans of
Kidston and with S. elongata of Bertrand.
Kidston’s sections of S. scutellata show a continuous primary xylem
cylinder with a slightly and irregularly crenulate outer margin. It would
seem that one important diagnostic character in Sigillarian stems is afforded
by the degree and form of the crenulations on the outer surface of the
primary xylem. S. scutellata has been described also by Arber and Thomas;
these authors were the first to demonstrate the presence of a ligule and
ligular pit on the leaf-base in a petrified stem, and they also contribute the
important fact that the leaf-traces in passing through the phelloderm
bifurcate and enter the leaf as two distinct vascular strands. This double
bundle has been referred to in the description of Sigillaria leaves. (page
214.)
Although our knowledge of the anatomy of Sigillaria has been
considerably extended since Williamson[532] drew attention to our
comparative ignorance of the subject, there are several points on which
information is either lacking or very meagre. As regards the stele, it is in all
types so far investigated, of the medullated type and constructed on the
same plan as that of Lepidodendron Wünschianum, L. Veltheimianum, and
other species. Secondary xylem was developed at an early stage of growth,
and its relation to the primary xylem, from which as Kidston points out in
his description of S. elegans, it may be separated by a few parenchymatous
elements, is like that in Lepidodendron. The tendency of the outer face of
the secondary xylem to present a crenulate appearance in transverse
sections may, as Scott thinks[533], be a feature of some diagnostic
importance, but this is not a constant character in the genus. In origin and in
their mesarch structure, the leaf-traces closely resemble those of
Lepidodendron. The earlier account of the structure of the leaf-traces of
Sigillaria, which were described as possessing both centrifugal and
centripetal wood, led Mettenius[534] to draw attention to an important
anatomical resemblance between this genus and modern Cycads. This
comparison was, however, based on a misconception; the Cycadean leaf-
trace, consisting solely of primary wood, is not strictly comparable with
those of some species of Sigillaria, in which one part of the xylem is
Scott[529], Kidston[530], and more recently, by Arber and Thomas[531].
The specimen described by Scott agrees in the main with S. elegans of
Kidston and with S. elongata of Bertrand.
Kidston’s sections of S. scutellata show a continuous primary xylem
cylinder with a slightly and irregularly crenulate outer margin. It would
seem that one important diagnostic character in Sigillarian stems is afforded
by the degree and form of the crenulations on the outer surface of the
primary xylem. S. scutellata has been described also by Arber and Thomas;
these authors were the first to demonstrate the presence of a ligule and
ligular pit on the leaf-base in a petrified stem, and they also contribute the
important fact that the leaf-traces in passing through the phelloderm
bifurcate and enter the leaf as two distinct vascular strands. This double
bundle has been referred to in the description of Sigillaria leaves. (page
214.)
Although our knowledge of the anatomy of Sigillaria has been
considerably extended since Williamson[532] drew attention to our
comparative ignorance of the subject, there are several points on which
information is either lacking or very meagre. As regards the stele, it is in all
types so far investigated, of the medullated type and constructed on the
same plan as that of Lepidodendron Wünschianum, L. Veltheimianum, and
other species. Secondary xylem was developed at an early stage of growth,
and its relation to the primary xylem, from which as Kidston points out in
his description of S. elegans, it may be separated by a few parenchymatous
elements, is like that in Lepidodendron. The tendency of the outer face of
the secondary xylem to present a crenulate appearance in transverse
sections may, as Scott thinks[533], be a feature of some diagnostic
importance, but this is not a constant character in the genus. In origin and in
their mesarch structure, the leaf-traces closely resemble those of
Lepidodendron. The earlier account of the structure of the leaf-traces of
Sigillaria, which were described as possessing both centrifugal and
centripetal wood, led Mettenius[534] to draw attention to an important
anatomical resemblance between this genus and modern Cycads. This
comparison was, however, based on a misconception; the Cycadean leaf-
trace, consisting solely of primary wood, is not strictly comparable with
those of some species of Sigillaria, in which one part of the xylem is
Page 257
primary and another secondary. The occasional presence of secondary
xylem in Sigillarian leaf-traces is matched in some Lepidodendra[535], and
cannot be accepted as a distinguishing feature.
The origin of the leaf-traces from the middle of the sinuses on the edge of
the primary xylem is regarded as a difference; in Lepidodendron the leaf-
traces are said to arise in some species from the sides of the crenulations;
but, as already pointed out, this is a distinction of doubtful value. The
division of the primary xylem into separate strands in some stems of
Sigillaria of the Clathrarian and Leiodermarian forms is a characteristic
peculiarity; but S. spinulosa forms a connecting link between this type and
the continuous arrangement of the xylem in S. elongata and S. elegans.
Kidston[536] has shown that the discontinuous primary xylem occurs in
Lower Permian species, a fact consistent with the view that the greater
abundance of the centripetally developed wood, characteristic of the older
species, represents a more primitive feature. This is not merely a conclusion
drawn from a consideration of geological age, but it is in harmony with the
view expressed by Scott[537] that as plants achieved greater success in
producing secondary centrifugal wood, the retention of any considerable
quantity of primary xylem became superfluous. As yet we know very little
of the structure of the perixylic tissues of Sigillaria, but there is no
sufficient reason for supposing that these differ in essentials from those in
Lepidodendron. The middle and outer cortical tissues are practically
identical in the two genera. The parichnos is of the same type, except that in
Sigillaria it reached greater dimensions in the outer part of its course.
v. Sigillaria Brardi[538] Brongniart.
Figs. 196, A–C; 200; 203.
xylem in Sigillarian leaf-traces is matched in some Lepidodendra[535], and
cannot be accepted as a distinguishing feature.
The origin of the leaf-traces from the middle of the sinuses on the edge of
the primary xylem is regarded as a difference; in Lepidodendron the leaf-
traces are said to arise in some species from the sides of the crenulations;
but, as already pointed out, this is a distinction of doubtful value. The
division of the primary xylem into separate strands in some stems of
Sigillaria of the Clathrarian and Leiodermarian forms is a characteristic
peculiarity; but S. spinulosa forms a connecting link between this type and
the continuous arrangement of the xylem in S. elongata and S. elegans.
Kidston[536] has shown that the discontinuous primary xylem occurs in
Lower Permian species, a fact consistent with the view that the greater
abundance of the centripetally developed wood, characteristic of the older
species, represents a more primitive feature. This is not merely a conclusion
drawn from a consideration of geological age, but it is in harmony with the
view expressed by Scott[537] that as plants achieved greater success in
producing secondary centrifugal wood, the retention of any considerable
quantity of primary xylem became superfluous. As yet we know very little
of the structure of the perixylic tissues of Sigillaria, but there is no
sufficient reason for supposing that these differ in essentials from those in
Lepidodendron. The middle and outer cortical tissues are practically
identical in the two genera. The parichnos is of the same type, except that in
Sigillaria it reached greater dimensions in the outer part of its course.
v. Sigillaria Brardi[538] Brongniart.
Figs. 196, A–C; 200; 203.
Page 258
1822. Clathraria Brardi, Brongniart, Classif. Vég. foss., Pl. xii. fig.
5.
1828. Sigillaria Brardi, Brongniart, Hist. Vég. foss. p. 430, Pl.
clviii. fig. 4.
S. Menardi, ibid. Pl. clviii.
1836. Lepidodendron Ottonis, Goeppert, Fossil Farnkr. Pl. xlii.
1839. S. elegans, Brongniart, Arch. Mus. Nat. Hist. Paris, Vol. i. p.
406, Pl. xxv.
1849. S. spinulosa, Germar, Verstein. Wettin und Löbejün, p. 59, Pl.
xxv.
1893. S. mutans, Weiss, Abhand. Preuss. Geol. Anst. [N.F.] Heft 2,
Pl. viii.
5.
1828. Sigillaria Brardi, Brongniart, Hist. Vég. foss. p. 430, Pl.
clviii. fig. 4.
S. Menardi, ibid. Pl. clviii.
1836. Lepidodendron Ottonis, Goeppert, Fossil Farnkr. Pl. xlii.
1839. S. elegans, Brongniart, Arch. Mus. Nat. Hist. Paris, Vol. i. p.
406, Pl. xxv.
1849. S. spinulosa, Germar, Verstein. Wettin und Löbejün, p. 59, Pl.
xxv.
1893. S. mutans, Weiss, Abhand. Preuss. Geol. Anst. [N.F.] Heft 2,
Pl. viii.
Page 259
Fig. 203. Sigillaria Brardi Brongn. (¾ nat. size). From a photograph of a specimen in Dr
Kidston’s collection, from the Upper Transition Series of Staffordshire. Published
by Kidston (02) Pl. lix. fig. 1.
The aerial shoots of this species are occasionally branched
dichotomously[539], the apical portions bearing short crowded leaves[540]; the
surface of the bark is either completely covered with contiguous leaf-scars
without definite leaf-cushions or with projecting cushions forming a narrow
sloping surface surrounding each leaf-scar. Other parts of the plant may
possess cushions similar in their kite-shaped form to those of
Lepidodendron, but without a median vertical groove, or the leaf-scars may
be spirally disposed at varying distances apart on a comparatively smooth
Kidston’s collection, from the Upper Transition Series of Staffordshire. Published
by Kidston (02) Pl. lix. fig. 1.
The aerial shoots of this species are occasionally branched
dichotomously[539], the apical portions bearing short crowded leaves[540]; the
surface of the bark is either completely covered with contiguous leaf-scars
without definite leaf-cushions or with projecting cushions forming a narrow
sloping surface surrounding each leaf-scar. Other parts of the plant may
possess cushions similar in their kite-shaped form to those of
Lepidodendron, but without a median vertical groove, or the leaf-scars may
be spirally disposed at varying distances apart on a comparatively smooth
Page 260
and longitudinally wrinkled bark. The species exhibits striking instances of
a transition between the Favularian, Clathrarian, and Leiodermarian forms
of stems. The leaf-scars, which are hexagonal in outline,—the lateral angles
pointed and transversely elongated, the upper and lower angles rounded,—
bear three scars, the central leaf-trace and two straight or curved lateral
parichnos scars; a ligular pit occurs immediately above the centre of the
upper edge of the leaf-scar and occasionally circular elevations with a
central pit occur singly or in pairs below a leaf-scar (fig. 196, A). The linear
leaves, which may persist on shoots having a fairly large diameter[541], have
a single median vein and two stomatal grooves on the lower surface[542] (fig.
200, D).
Partially decorticated and younger shoots are characterised by the
occurrence of pairs of elliptical parichnos areas and a smaller median leaf-
trace scar. The surface of older stems, which may show signs of
longitudinal splitting (Syringodendron state), bears pairs of parichnos scars
reaching a length of 2–2·5 cm. and a breadth of 10–13 mm. The regularity
of the leaf-scar arrangement is interrupted at intervals by the occurrence of
more or less regular verticils of scars marking the position of deciduous
shoots. Grand’Eury[543] has figured cones which he believes to be those of
this species, and Zeiller refers the large strobili, Sigillariostrobus major, to
Sigillaria Brardi[544].
The subterranean axes were characterised by spirally disposed rootlet-
scars like those of Stigmaria ficoides (figs. 204, 205) and by a cortical
surface with the features of Stigmaria rimosa Gold.[545]
The anatomy of the stele and leaves has already been described (p. 219).
The stele of the Stigmarian portion of the plant consists of a band of
centripetal primary xylem and a cylinder of centrifugally formed secondary
wood with medullary rays containing vascular bundles passing out to the
rootlets[546].
Sigillaria Brardi occurs not uncommonly in Permian rocks; it is recorded
from France[547], Germany[548], Pennsylvania[549], and elsewhere. It is found
in the Upper, Middle, and Lower Coal-Measures of England[550] and in
Permo-Carboniferous strata in Africa[551] and Brazil[552].
a transition between the Favularian, Clathrarian, and Leiodermarian forms
of stems. The leaf-scars, which are hexagonal in outline,—the lateral angles
pointed and transversely elongated, the upper and lower angles rounded,—
bear three scars, the central leaf-trace and two straight or curved lateral
parichnos scars; a ligular pit occurs immediately above the centre of the
upper edge of the leaf-scar and occasionally circular elevations with a
central pit occur singly or in pairs below a leaf-scar (fig. 196, A). The linear
leaves, which may persist on shoots having a fairly large diameter[541], have
a single median vein and two stomatal grooves on the lower surface[542] (fig.
200, D).
Partially decorticated and younger shoots are characterised by the
occurrence of pairs of elliptical parichnos areas and a smaller median leaf-
trace scar. The surface of older stems, which may show signs of
longitudinal splitting (Syringodendron state), bears pairs of parichnos scars
reaching a length of 2–2·5 cm. and a breadth of 10–13 mm. The regularity
of the leaf-scar arrangement is interrupted at intervals by the occurrence of
more or less regular verticils of scars marking the position of deciduous
shoots. Grand’Eury[543] has figured cones which he believes to be those of
this species, and Zeiller refers the large strobili, Sigillariostrobus major, to
Sigillaria Brardi[544].
The subterranean axes were characterised by spirally disposed rootlet-
scars like those of Stigmaria ficoides (figs. 204, 205) and by a cortical
surface with the features of Stigmaria rimosa Gold.[545]
The anatomy of the stele and leaves has already been described (p. 219).
The stele of the Stigmarian portion of the plant consists of a band of
centripetal primary xylem and a cylinder of centrifugally formed secondary
wood with medullary rays containing vascular bundles passing out to the
rootlets[546].
Sigillaria Brardi occurs not uncommonly in Permian rocks; it is recorded
from France[547], Germany[548], Pennsylvania[549], and elsewhere. It is found
in the Upper, Middle, and Lower Coal-Measures of England[550] and in
Permo-Carboniferous strata in Africa[551] and Brazil[552].
Page 261
Page 262
CHAPTER XVII.
UNDERGROUND RHIZOMES AND ROOTS OF PALAEOZOIC
LYCOPODIACEOUS PLANTS.
Stigmaria.
Stigmaria ficoides is the name given to cylindrical casts met with in
Palaeozoic rocks, from the Devonian[553] to the Permian[554], characterised by
a smooth or irregularly wrinkled surface bearing spirally disposed circular
scars bounded by a raised rim and containing a small central pit. It is not
uncommon to find evidence of a partial collapse of the substance of the
plant as seen in fig. 204; this is doubtless the expression of a shrinkage of
the middle cortical region, which was composed of a delicate and lacunar
system of cells. There can be no reasonable doubt that Stigmaria grew in
water or in swampy ground. Specimens are occasionally met with in which
the cast terminates in a bluntly rounded apex; such are, perhaps, young
branches which have not grown far from the base of the aerial stem from
which they arose (cf. fig. 207, B, C). Other examples occur, such as
Goeppert[555] figured and Gresley[556] has more recently described, which are
twisted and distorted as though obstacles had been encountered in the
ground in which they grew.
UNDERGROUND RHIZOMES AND ROOTS OF PALAEOZOIC
LYCOPODIACEOUS PLANTS.
Stigmaria.
Stigmaria ficoides is the name given to cylindrical casts met with in
Palaeozoic rocks, from the Devonian[553] to the Permian[554], characterised by
a smooth or irregularly wrinkled surface bearing spirally disposed circular
scars bounded by a raised rim and containing a small central pit. It is not
uncommon to find evidence of a partial collapse of the substance of the
plant as seen in fig. 204; this is doubtless the expression of a shrinkage of
the middle cortical region, which was composed of a delicate and lacunar
system of cells. There can be no reasonable doubt that Stigmaria grew in
water or in swampy ground. Specimens are occasionally met with in which
the cast terminates in a bluntly rounded apex; such are, perhaps, young
branches which have not grown far from the base of the aerial stem from
which they arose (cf. fig. 207, B, C). Other examples occur, such as
Goeppert[555] figured and Gresley[556] has more recently described, which are
twisted and distorted as though obstacles had been encountered in the
ground in which they grew.
Page 263
Fig. 204. Stigmaria ficoides Brongn. M.S. (See Vol. i. p. 73.)
Fig. 205. Stigmaria ficoides. From a specimen in the York Museum, from Bishop Auckland.
a, base of rootlet showing vascular bundle scar. M.S.
Fig. 205. Stigmaria ficoides. From a specimen in the York Museum, from Bishop Auckland.
a, base of rootlet showing vascular bundle scar. M.S.
Page 264
The circular scars mark the bases of long single and occasionally forked
appendages (rootlets) which spread on all sides into the surrounding
medium (figs. 205, 208). The occurrence of rootlets radiating through the
shale or sandstone affords proof that the Stigmarias are often preserved in
their position of growth. This was recognised by Steinhauer[557] and
Logan[558], and has been more recently emphasised by Potonié[559] as an
argument in favour of the view that the beds containing such specimens are
old surface-soils.
Stigmaria usually shows regular dichotomous branching, the arms
spreading horizontally or slightly downwards and always arising from four
main branches in the form of a cross (fig. 207). The most remarkable
specimens found in England are described by Williamson[560] in his
monograph of Stigmaria. One of two large casts found near Bradford in
Yorkshire, and now in the Manchester Museum, shows four large primary
arms radiating from the base of an erect stump 4 feet in diameter. Each arm
divides a short distance from its base into two, and the smaller branches
extend almost horizontally for several feet[561].
An illustration published by Martin in 1809[562] shows a characteristic
feature of Stigmarian casts, namely the presence of a smaller axis, usually
occupying an eccentric position inside the larger. This represents the cast of
the fairly broad parenchymatous pith which, on decay, left a space
subsequently filled by sand or mud: at a later stage the surrounding wood
and cortex were removed and the cavity so formed was similarly filled. A
thin layer of coal formed by the carbonisation of some of the tissues
frequently surrounds the medullary cast, and Steinhauer, whose account of
the genus is much fuller and more scientific than those of other earlier and
many later writers, recognised the true nature of this internal cast. Artis[563]
regarded it as the remains of a young plant, which he described as
“perforating its parent,” at length bursting it and assuming its place, a
gratuitously drastic interpretation.
In 1838[564] Lindley and Hutton figured a partially petrified specimen of
Stigmaria obtained by Prestwich from Carboniferous rock of Shropshire.
This example showed a fairly broad cylinder of secondary wood penetrated
by medullary rays. The medullated stele consisted of a pith surrounded by a
small amount of primary xylem and by a cylinder of secondary scalariform
tracheae. The preservation of the tissues abutting on the edge of the wood is
appendages (rootlets) which spread on all sides into the surrounding
medium (figs. 205, 208). The occurrence of rootlets radiating through the
shale or sandstone affords proof that the Stigmarias are often preserved in
their position of growth. This was recognised by Steinhauer[557] and
Logan[558], and has been more recently emphasised by Potonié[559] as an
argument in favour of the view that the beds containing such specimens are
old surface-soils.
Stigmaria usually shows regular dichotomous branching, the arms
spreading horizontally or slightly downwards and always arising from four
main branches in the form of a cross (fig. 207). The most remarkable
specimens found in England are described by Williamson[560] in his
monograph of Stigmaria. One of two large casts found near Bradford in
Yorkshire, and now in the Manchester Museum, shows four large primary
arms radiating from the base of an erect stump 4 feet in diameter. Each arm
divides a short distance from its base into two, and the smaller branches
extend almost horizontally for several feet[561].
An illustration published by Martin in 1809[562] shows a characteristic
feature of Stigmarian casts, namely the presence of a smaller axis, usually
occupying an eccentric position inside the larger. This represents the cast of
the fairly broad parenchymatous pith which, on decay, left a space
subsequently filled by sand or mud: at a later stage the surrounding wood
and cortex were removed and the cavity so formed was similarly filled. A
thin layer of coal formed by the carbonisation of some of the tissues
frequently surrounds the medullary cast, and Steinhauer, whose account of
the genus is much fuller and more scientific than those of other earlier and
many later writers, recognised the true nature of this internal cast. Artis[563]
regarded it as the remains of a young plant, which he described as
“perforating its parent,” at length bursting it and assuming its place, a
gratuitously drastic interpretation.
In 1838[564] Lindley and Hutton figured a partially petrified specimen of
Stigmaria obtained by Prestwich from Carboniferous rock of Shropshire.
This example showed a fairly broad cylinder of secondary wood penetrated
by medullary rays. The medullated stele consisted of a pith surrounded by a
small amount of primary xylem and by a cylinder of secondary scalariform
tracheae. The preservation of the tissues abutting on the edge of the wood is
Page 265
usually very imperfect, and the middle cortex of lacunar parenchyma has
practically in every case eluded the action of mineralising agents; the outer
cortex, on the other hand, consists of more resistant elements and is
frequently well preserved. As in Lepidodendron and Sigillaria stems,
meristematic activity produced a broad band of secondary cortex; and
beyond this were attached to cushion-like pads the numerous appendages,
each supplied with a single vascular bundle which arose from the primary
xylem and passed outwards through a medullary ray. There is abundant
evidence that the appendages were hollow, a fact in striking accord with the
aquatic and semi-aquatic habitat (cf. Isoetes root, fig. 133, G).
Fig. 206. Cyperus papyrus. Piece of rhizome showing rootlet-scars. Nat. size. M.S.
The piece of dried rhizome of Cyperus papyrus shown in fig. 206 is an
almost exact counterpart of Stigmaria ficoides; the wrinkled and shrivelled
surface and the circular root-scars containing the remains of a vascular
bundle are striking features in common and, it may be added, the two
plants, though very different in structure and in systematic position,
illustrate anatomical adaptations to a similar environment.
Stigmaria ficoides Brongniart[565]. Figs. 204, 205, 207, 208.
practically in every case eluded the action of mineralising agents; the outer
cortex, on the other hand, consists of more resistant elements and is
frequently well preserved. As in Lepidodendron and Sigillaria stems,
meristematic activity produced a broad band of secondary cortex; and
beyond this were attached to cushion-like pads the numerous appendages,
each supplied with a single vascular bundle which arose from the primary
xylem and passed outwards through a medullary ray. There is abundant
evidence that the appendages were hollow, a fact in striking accord with the
aquatic and semi-aquatic habitat (cf. Isoetes root, fig. 133, G).
Fig. 206. Cyperus papyrus. Piece of rhizome showing rootlet-scars. Nat. size. M.S.
The piece of dried rhizome of Cyperus papyrus shown in fig. 206 is an
almost exact counterpart of Stigmaria ficoides; the wrinkled and shrivelled
surface and the circular root-scars containing the remains of a vascular
bundle are striking features in common and, it may be added, the two
plants, though very different in structure and in systematic position,
illustrate anatomical adaptations to a similar environment.
Stigmaria ficoides Brongniart[565]. Figs. 204, 205, 207, 208.
Page 266
1809. Phytolithus verrucosus, Martin, Petrifact. Derb. Pls. xi–xiv.
1818. Phytolithus verrucosus, Steinhauer, Trans. Phil. Soc. America,
[N.S.] Vol. i. p. 268, Pl. iv.
1820. Variolaria ficoides, Sternberg, Flora der Vorwelt, p. 22, Pl. xii.
1822. Stigmaria ficoides, Brongniart, Mem. Mus. d’hist. nat. Paris,
Pl. xii. fig. 7, p. 228.
1825. Ficoidites verrucosus, Artis, Antediluvian Phytology, Pl. x.
1840. Stigmaria anabathra, Corda, Flor. der Vorwelt, Pl. xiv.
The first figure of Stigmaria is said to be by Petver in 1704; Volkmann
published illustrations of this common fossil in 1720 and Parkinson in
1804[566]. Binney, whose researches may be said to have inaugurated a new
era in the investigation of fossil plants, wrote in 1844: “Probably no fossil
plant has excited more discussion among botanists than the Stigmaria. It is
the most common of the whole number of plants found in the Coal-
Measures, but there has hitherto been the greatest uncertainty as to its real
nature[567].” This uncertainty still exists, at least in the minds of some who
know enough of the available data to realise that our knowledge is
imperfect.
To pass to the questions of the affinity and nature of Stigmaria:
Brongniart[568] at first compared his genus with recent Aroideae, but he
afterwards[569] spoke of it as probably the root of Sigillaria. Other writers
regarded Stigmaria as a dicotyledonous plant comparable with Cacti and
succulent Euphorbias. For many years opinion was divided as to whether
Stigmaria represents an independent and complete plant or the underground
system of Sigillaria.
Artis[570], Lindley and Hutton[571], as well as Goldenberg[572], believed it to
be a prostrate plant unconnected with any erect aerial stem. Goldenberg
figured one of the slender rootlets terminating in an oval body described as
a reproductive organ. This seed-like impression is either some extraneous
body or an abnormal development at the end of a rootlet. In 1842 Logan
drew attention to the almost complete monopolisation by Stigmaria of the
underclays, the rock which as a general rule occurs below a seam of coal.
He wrote: “The grand distinguishing feature of the underclays is the
peculiar character of the vegetable organic remains; they are always of one
kind (Stigmaria ficoides) and are so diffused throughout every part of the
1818. Phytolithus verrucosus, Steinhauer, Trans. Phil. Soc. America,
[N.S.] Vol. i. p. 268, Pl. iv.
1820. Variolaria ficoides, Sternberg, Flora der Vorwelt, p. 22, Pl. xii.
1822. Stigmaria ficoides, Brongniart, Mem. Mus. d’hist. nat. Paris,
Pl. xii. fig. 7, p. 228.
1825. Ficoidites verrucosus, Artis, Antediluvian Phytology, Pl. x.
1840. Stigmaria anabathra, Corda, Flor. der Vorwelt, Pl. xiv.
The first figure of Stigmaria is said to be by Petver in 1704; Volkmann
published illustrations of this common fossil in 1720 and Parkinson in
1804[566]. Binney, whose researches may be said to have inaugurated a new
era in the investigation of fossil plants, wrote in 1844: “Probably no fossil
plant has excited more discussion among botanists than the Stigmaria. It is
the most common of the whole number of plants found in the Coal-
Measures, but there has hitherto been the greatest uncertainty as to its real
nature[567].” This uncertainty still exists, at least in the minds of some who
know enough of the available data to realise that our knowledge is
imperfect.
To pass to the questions of the affinity and nature of Stigmaria:
Brongniart[568] at first compared his genus with recent Aroideae, but he
afterwards[569] spoke of it as probably the root of Sigillaria. Other writers
regarded Stigmaria as a dicotyledonous plant comparable with Cacti and
succulent Euphorbias. For many years opinion was divided as to whether
Stigmaria represents an independent and complete plant or the underground
system of Sigillaria.
Artis[570], Lindley and Hutton[571], as well as Goldenberg[572], believed it to
be a prostrate plant unconnected with any erect aerial stem. Goldenberg
figured one of the slender rootlets terminating in an oval body described as
a reproductive organ. This seed-like impression is either some extraneous
body or an abnormal development at the end of a rootlet. In 1842 Logan
drew attention to the almost complete monopolisation by Stigmaria of the
underclays, the rock which as a general rule occurs below a seam of coal.
He wrote: “The grand distinguishing feature of the underclays is the
peculiar character of the vegetable organic remains; they are always of one
kind (Stigmaria ficoides) and are so diffused throughout every part of the
Page 267
bed, that by their uniform effect alone the clay is readily recognised by the
eye of the miner[573].” This fact, which has played a very conspicuous part in
the perennial discussions on the origin of coal, led to the almost general
recognition of the underclays as surface-soils of the Coal period forests.
The next step was the discovery of Stigmaria in the Coal-Measures of
Lancashire and in the Carboniferous rocks of Cape Breton, Nova Scotia,
forming the basal branches of erect stems identified by Binney[574],
Bowman[575] and Richard Brown[576] as undoubted Sigillariae. In one case
Brown found what he considered to be convincing evidence of the
continuity between Stigmaria and Lepidodendron.
In 1842 Hawkshaw[577] described certain fossil trees, the largest of which
had a circumference at the base of 15 ft., discovered, in the course of
excavations for a railway in Lancashire, in soft shale at right angles to the
bedding. The surface features were not sufficiently clear to enable him to
decide with certainty between Sigillaria and Lepidodendron, but while
inclining to the former, it is interesting to note that the occurrence of
numerous Lepidostrobi near the root led him to recognise the possibility of
a connexion between the Stigmarian roots and Lepidodendron stems. In
1846 Binney gave an account of similar trees found at Dukinfield near
Manchester: he spoke of one stem as unquestionably a Sigillaria with
vertical ribs, furrows, and scars, about 15 inches high and 4 ft. 10 inches in
circumference. He expressed his conviction that “Sigillaria was a plant of
an aquatic nature[578].” Similar descriptions of rooted stems in the Coal-
Measures of Nova Scotia were published by Brown in 1845, 1846 and
1849; in the last paper he figured a specimen, which has become famous,
showing a Syringodendron stem terminating in branching Stigmarian (or
possibly Stigmariopsis) roots bearing on the lower surface a series of what
he called conical tap roots[579]. A similar specimen discovered in Central
France nearly fifty years later demonstrated the accuracy of Brown’s
description.
Despite these discoveries the root-like nature of Stigmaria was not
universally accepted. It was, however, generally agreed that Stigmaria
formed the roots of Sigillaria; it was, moreover, held by some that
Lepidodendron stems also possessed this type of root, an opinion based on
Brown’s record and on the occurrence of Stigmaria in beds containing
Lepidodendron but no Sigillaria stems, as in the volcanic beds of Arran and
eye of the miner[573].” This fact, which has played a very conspicuous part in
the perennial discussions on the origin of coal, led to the almost general
recognition of the underclays as surface-soils of the Coal period forests.
The next step was the discovery of Stigmaria in the Coal-Measures of
Lancashire and in the Carboniferous rocks of Cape Breton, Nova Scotia,
forming the basal branches of erect stems identified by Binney[574],
Bowman[575] and Richard Brown[576] as undoubted Sigillariae. In one case
Brown found what he considered to be convincing evidence of the
continuity between Stigmaria and Lepidodendron.
In 1842 Hawkshaw[577] described certain fossil trees, the largest of which
had a circumference at the base of 15 ft., discovered, in the course of
excavations for a railway in Lancashire, in soft shale at right angles to the
bedding. The surface features were not sufficiently clear to enable him to
decide with certainty between Sigillaria and Lepidodendron, but while
inclining to the former, it is interesting to note that the occurrence of
numerous Lepidostrobi near the root led him to recognise the possibility of
a connexion between the Stigmarian roots and Lepidodendron stems. In
1846 Binney gave an account of similar trees found at Dukinfield near
Manchester: he spoke of one stem as unquestionably a Sigillaria with
vertical ribs, furrows, and scars, about 15 inches high and 4 ft. 10 inches in
circumference. He expressed his conviction that “Sigillaria was a plant of
an aquatic nature[578].” Similar descriptions of rooted stems in the Coal-
Measures of Nova Scotia were published by Brown in 1845, 1846 and
1849; in the last paper he figured a specimen, which has become famous,
showing a Syringodendron stem terminating in branching Stigmarian (or
possibly Stigmariopsis) roots bearing on the lower surface a series of what
he called conical tap roots[579]. A similar specimen discovered in Central
France nearly fifty years later demonstrated the accuracy of Brown’s
description.
Despite these discoveries the root-like nature of Stigmaria was not
universally accepted. It was, however, generally agreed that Stigmaria
formed the roots of Sigillaria; it was, moreover, held by some that
Lepidodendron stems also possessed this type of root, an opinion based on
Brown’s record and on the occurrence of Stigmaria in beds containing
Lepidodendron but no Sigillaria stems, as in the volcanic beds of Arran and
Page 268
elsewhere, and on observations of Geinitz and others[580]. There is now
general agreement that Lepidodendron and Sigillaria had the same type of
“root,” though the connexion of Stigmaria with the former was not so
readily admitted, and indeed the evidence in support of it is still very
meagre. Goeppert and other authors were unable to believe that the
numerous species of Sigillaria possessed roots of so uniform a type, but
Goeppert, by his recognition of several varieties of Stigmaria, supplied a
partial answer to this objection.
Messrs Mellor and Leslie[581] have described and figured some large casts
of roots exposed in Permo-Carboniferous rocks in the bed of the Vaal river
at Vereeniging (Transvaal) which exhibit certain features suggesting
comparison with Stigmaria. Some of these reach a length of 40–50 feet and,
when complete, were probably not less than 100 feet long: in some of them
the centre of the cast from which forked arms spread almost horizontally
shows a depression in the form of a cross indicating a regular dichotomous
branching like that of Stigmaria. The authors incline to the belief that the
roots belong to Noeggerathiopsis and not to a lycopodiaceous plant, though
Lepidodendroid stems are abundant in the sandstone a few feet higher in the
series. Despite the absence of any Stigmarian scars on the surface of the
fossil it is probable that these fine specimens are the rhizomes of some
lycopodiaceous plant, possibly Bothrodendron, which is not uncommon in
the Vereeniging beds.
Admitting that Stigmaria is part of Sigillaria, the next question is, is
Stigmaria a root in the ordinary sense, the underground system formed on
germination of the spore and of equal age with the shoot, or did it bear a
different relation to the Sigillarian stems? To this question different answers
would still be given. Goeppert[582] discussed evidence in favour of the view
that aerial Sigillarian shoots were produced as vegetative buds on pre-
existing Stigmarian axes, like young moss plants on a protonema. At a later
date Renault[583] developed a similar view as regards Sigillaria; but we may
pass on to consider the more recent and complete observations of
Grand’Eury[584] and Solms-Laubach[585].
The recognition of two distinct types of Stigmariae in the Coal-Measures
of Central France led Grand’Eury[586] to institute a new genus,
Stigmariopsis. This type, which is characterised by a difference in habit as
well as by other distinguishing features, is represented by such specimens
general agreement that Lepidodendron and Sigillaria had the same type of
“root,” though the connexion of Stigmaria with the former was not so
readily admitted, and indeed the evidence in support of it is still very
meagre. Goeppert and other authors were unable to believe that the
numerous species of Sigillaria possessed roots of so uniform a type, but
Goeppert, by his recognition of several varieties of Stigmaria, supplied a
partial answer to this objection.
Messrs Mellor and Leslie[581] have described and figured some large casts
of roots exposed in Permo-Carboniferous rocks in the bed of the Vaal river
at Vereeniging (Transvaal) which exhibit certain features suggesting
comparison with Stigmaria. Some of these reach a length of 40–50 feet and,
when complete, were probably not less than 100 feet long: in some of them
the centre of the cast from which forked arms spread almost horizontally
shows a depression in the form of a cross indicating a regular dichotomous
branching like that of Stigmaria. The authors incline to the belief that the
roots belong to Noeggerathiopsis and not to a lycopodiaceous plant, though
Lepidodendroid stems are abundant in the sandstone a few feet higher in the
series. Despite the absence of any Stigmarian scars on the surface of the
fossil it is probable that these fine specimens are the rhizomes of some
lycopodiaceous plant, possibly Bothrodendron, which is not uncommon in
the Vereeniging beds.
Admitting that Stigmaria is part of Sigillaria, the next question is, is
Stigmaria a root in the ordinary sense, the underground system formed on
germination of the spore and of equal age with the shoot, or did it bear a
different relation to the Sigillarian stems? To this question different answers
would still be given. Goeppert[582] discussed evidence in favour of the view
that aerial Sigillarian shoots were produced as vegetative buds on pre-
existing Stigmarian axes, like young moss plants on a protonema. At a later
date Renault[583] developed a similar view as regards Sigillaria; but we may
pass on to consider the more recent and complete observations of
Grand’Eury[584] and Solms-Laubach[585].
The recognition of two distinct types of Stigmariae in the Coal-Measures
of Central France led Grand’Eury[586] to institute a new genus,
Stigmariopsis. This type, which is characterised by a difference in habit as
well as by other distinguishing features, is represented by such specimens
Page 269
as those figured by Goldenberg as Stigmaria abbreviata, bearing lenticular
scars spirally disposed on a cortical surface characterised by irregular
longitudinal wrinklings. Stigmariopsis has frequently been found in direct
continuity with Sigillarian stems of the Leiodermarian-Clathrarian type,
spreading obliquely downwards in the form of rapidly narrowing arms
clothed with slender and usually simple appendages; and from the under
surface of these arms short conical outgrowths are given off. It is probable,
as Solms-Laubach believes, that Stigmariopsis was represented also by long
horizontally creeping rhizomes[587] of uniform breadth from which ribless
Sigillarian aerial shoots arose as bud-like outgrowths. Grand’Eury, the
author of the genus, confined the term to the shorter and more rapidly
tapered organs spreading from the base of erect stems; the horizontal
rhizomes of all Sigillarian stems he refers to Stigmaria. The pith-casts of
Sigillariopsis may be recognised by their long vertical ridges and grooves, a
feature readily understood by reference to the stem structure. The
Stigmariopsis rhizomes though rare in England have been recognised by Dr
Kidston[588] in the Middle Coal-Measures of Yorkshire; he has figured a
pith-cast very like that illustrated in Solms-Laubach’s Memoir as
Stigmariopsis anglica.
The surface-features of a Stigmariopsis pith-cast are clearly shown on a
specimen from St Étienne in the Williamson collection[589].
STIGMARIOPSIS
The most complete account of Grand’Eury’s views in regard to the
anchoring and absorbing organs of Sigillaria is given in his monograph on
the Coal-field of Gard[590], St Étienne, and these are clearly stated also by
Solms-Laubach[591] who confirms the conclusions of the French author as to
the manner of development of the aerial shoots. Grand’Eury believes that
both Stigmaria and Stigmariopsis are rhizomes and not true roots. The
surface-features of Stigmaria have already been described. This type
Grand’Eury speaks of as characterised by the uniform diameter and
considerable horizontal elongation of the bifurcated axes; he thinks they
grew both as floating rhizomes and on the ground: they may frequently be
traced for a considerable distance without showing any signs of connexion
with aerial shoots, but occasionally they have been seen in organic union
with Sigillarian stems. He believes that these rhizomes were produced as
the result of germination under water of the spores of Sigillaria or
scars spirally disposed on a cortical surface characterised by irregular
longitudinal wrinklings. Stigmariopsis has frequently been found in direct
continuity with Sigillarian stems of the Leiodermarian-Clathrarian type,
spreading obliquely downwards in the form of rapidly narrowing arms
clothed with slender and usually simple appendages; and from the under
surface of these arms short conical outgrowths are given off. It is probable,
as Solms-Laubach believes, that Stigmariopsis was represented also by long
horizontally creeping rhizomes[587] of uniform breadth from which ribless
Sigillarian aerial shoots arose as bud-like outgrowths. Grand’Eury, the
author of the genus, confined the term to the shorter and more rapidly
tapered organs spreading from the base of erect stems; the horizontal
rhizomes of all Sigillarian stems he refers to Stigmaria. The pith-casts of
Sigillariopsis may be recognised by their long vertical ridges and grooves, a
feature readily understood by reference to the stem structure. The
Stigmariopsis rhizomes though rare in England have been recognised by Dr
Kidston[588] in the Middle Coal-Measures of Yorkshire; he has figured a
pith-cast very like that illustrated in Solms-Laubach’s Memoir as
Stigmariopsis anglica.
The surface-features of a Stigmariopsis pith-cast are clearly shown on a
specimen from St Étienne in the Williamson collection[589].
STIGMARIOPSIS
The most complete account of Grand’Eury’s views in regard to the
anchoring and absorbing organs of Sigillaria is given in his monograph on
the Coal-field of Gard[590], St Étienne, and these are clearly stated also by
Solms-Laubach[591] who confirms the conclusions of the French author as to
the manner of development of the aerial shoots. Grand’Eury believes that
both Stigmaria and Stigmariopsis are rhizomes and not true roots. The
surface-features of Stigmaria have already been described. This type
Grand’Eury speaks of as characterised by the uniform diameter and
considerable horizontal elongation of the bifurcated axes; he thinks they
grew both as floating rhizomes and on the ground: they may frequently be
traced for a considerable distance without showing any signs of connexion
with aerial shoots, but occasionally they have been seen in organic union
with Sigillarian stems. He believes that these rhizomes were produced as
the result of germination under water of the spores of Sigillaria or
Page 270
Lepidodendron and developed as long and branched aquatic rhizomes
capable of independent existence. Under certain conditions, as he thinks in
shallower water, the rhizomes produced bulb-like outgrowths which grew
into erect stems having the surface-features of Sigillaria. This method of
origin is practically the same as that described by Goeppert in 1865. The
vascular medullated cylinder of these erect branches was in direct
continuity with that of the Stigmarian rhizomes.
Fig. 208. Later stage in the development of
Sigillaria; Syringodendron with
Stigmariopsis. (After Grand’Eury.)
Fig. 207. An early stage in the development
of Sigillaria.
A. Surface-features enlarged.
(After Grand’Eury.)
The next stage is that in which the undifferentiated bulb becomes swollen
at the base and develops four primary roots (fig. 207 B, C) which grow
obliquely downwards and produce numerous rootlets. Meanwhile the parent
rhizome gradually decays, finally setting free the aerial stems which are
now provided with spreading and forked roots (fig. 208) such as we are
familiar with in English specimens as Stigmaria ficoides, but which in the
capable of independent existence. Under certain conditions, as he thinks in
shallower water, the rhizomes produced bulb-like outgrowths which grew
into erect stems having the surface-features of Sigillaria. This method of
origin is practically the same as that described by Goeppert in 1865. The
vascular medullated cylinder of these erect branches was in direct
continuity with that of the Stigmarian rhizomes.
Fig. 208. Later stage in the development of
Sigillaria; Syringodendron with
Stigmariopsis. (After Grand’Eury.)
Fig. 207. An early stage in the development
of Sigillaria.
A. Surface-features enlarged.
(After Grand’Eury.)
The next stage is that in which the undifferentiated bulb becomes swollen
at the base and develops four primary roots (fig. 207 B, C) which grow
obliquely downwards and produce numerous rootlets. Meanwhile the parent
rhizome gradually decays, finally setting free the aerial stems which are
now provided with spreading and forked roots (fig. 208) such as we are
familiar with in English specimens as Stigmaria ficoides, but which in the
Page 271
French specimens show the features of Stigmariopsis. At this later stage
conical outgrowths are formed from the under surface of the Stigmariopsis
arranged in a more or less regular series surrounding the centre of the
forked and spreading roots (fig. 209). These conical and positively
geotropic organs were long ago described by Richard Brown as tap-roots.
Grand’Eury’s conclusions are briefly as follows: Sigillaria, and we may add
Lepidodendron, had no true roots and in this respect are comparable with
Psilotum (fig. 118): the organs which are described by Grand’Eury as roots
are correctly so named in a physiological sense, but morphologically they
do not strictly conform, either in origin or in the arrangement of their
appendages, to true roots. The question as to whether they are entitled to the
designation root is one which it is needless and indeed futile to discuss in
detail; it would be conceding too much to a formal academic standpoint to
refrain from applying to them the term root, as that best describes their
share in the life of the Sigillarian stems. The horizontal Stigmarian axes are
rhizomes in the ordinary sense of the term and from these were developed
Sigillarian shoots, characterised in the lower portions by large parichnos
strands. From the base of the young bulbous shoots roots were formed:
these roots being, in the French specimens, of the Stigmariopsis type.
Fig. 209. Stigmariopsis and “tap-roots.” (After Grand’Eury.)
These conclusions require some modification when applied to British
representatives of the arborescent Lycopodiales. The long spreading and
dichotomously branched root-like organs attached to the base of Sigillarian
and Lepidodendron stems are true examples of Stigmaria ficoides or other
species. Stigmariopsis occurs but rarely. This marked difference between
French and English specimens may be explained if we adopt the opinion of
conical outgrowths are formed from the under surface of the Stigmariopsis
arranged in a more or less regular series surrounding the centre of the
forked and spreading roots (fig. 209). These conical and positively
geotropic organs were long ago described by Richard Brown as tap-roots.
Grand’Eury’s conclusions are briefly as follows: Sigillaria, and we may add
Lepidodendron, had no true roots and in this respect are comparable with
Psilotum (fig. 118): the organs which are described by Grand’Eury as roots
are correctly so named in a physiological sense, but morphologically they
do not strictly conform, either in origin or in the arrangement of their
appendages, to true roots. The question as to whether they are entitled to the
designation root is one which it is needless and indeed futile to discuss in
detail; it would be conceding too much to a formal academic standpoint to
refrain from applying to them the term root, as that best describes their
share in the life of the Sigillarian stems. The horizontal Stigmarian axes are
rhizomes in the ordinary sense of the term and from these were developed
Sigillarian shoots, characterised in the lower portions by large parichnos
strands. From the base of the young bulbous shoots roots were formed:
these roots being, in the French specimens, of the Stigmariopsis type.
Fig. 209. Stigmariopsis and “tap-roots.” (After Grand’Eury.)
These conclusions require some modification when applied to British
representatives of the arborescent Lycopodiales. The long spreading and
dichotomously branched root-like organs attached to the base of Sigillarian
and Lepidodendron stems are true examples of Stigmaria ficoides or other
species. Stigmariopsis occurs but rarely. This marked difference between
French and English specimens may be explained if we adopt the opinion of
Page 272
Solms-Laubach, who believes that the true Stigmaria represents both the
parent rhizome and the later-formed roots of the Rhytidolepis Sigillarian
species and of Lepidodendron, the Stigmariopsis form having the
corresponding relation to the Leiodermarian-Clathrarian species.
The opinion expressed by Williamson[592] in 1892 that Grand’Eury’s
hypothesis “appears to be identical with the vague and speculative guesses
that were prevalent among us in the early years of the present [nineteenth]
century” illustrates the strength of conviction based on English specimens
as to the root-nature of Stigmaria.
There is undoubtedly considerable confusion, which can be cleared up
only by further research, as to the precise relation between Stigmaria and
Stigmariopsis on the one hand and the different types of Sigillariae on the
other. The main contention, and this is the most important point, of Renault,
Grand’Eury and Solms-Laubach as to the manner of formation of the aerial
shoots from rhizomes and the subsequent production of forked roots and
their ultimate separation from the parent rhizome is, as I believe, correct.
Williamson held that Stigmaria must be regarded as a true root; he found no
evidence to support the view that the large rooted stem discovered by
Hawshaw, Binney, and others had been originally produced from aquatic
rhizomes. It must, however, be remembered that Grand’Eury’s opinion is
based on evidence afforded by the exceptionally well displayed Sigillarian
forests of St Étienne, on a scale such as English strata have not as yet
afforded. Moreover, the absence of any parent-rhizome in association with
the rooted stumps described by Williamson and by others is not a serious
argument against their rhizome origin.
The specimen represented in fig. 209, which was examined in situ by
Solms-Laubach and Grand’Eury, shows a Sigillarian stem in the
Syringodendron condition bearing rows of paired parichnos scars; from the
base forked and rapidly tapering arms radiate through the surrounding rock
and, as shown by other specimens, these bear numerous appendages like
those of the English Stigmarias. The surface-features of the arms are those
of Stigmariopsis and the centre of each, as seen on the broken face, is
occupied by a pith-cast characterised by parallel longitudinal ridges
resembling those on the medullary casts of Calamites. It is noteworthy that
the petrified rhizome originally described by Renault as Stigmaria flexuosa,
and afterwards identified by him as the subterranean system of Sigillaria
parent rhizome and the later-formed roots of the Rhytidolepis Sigillarian
species and of Lepidodendron, the Stigmariopsis form having the
corresponding relation to the Leiodermarian-Clathrarian species.
The opinion expressed by Williamson[592] in 1892 that Grand’Eury’s
hypothesis “appears to be identical with the vague and speculative guesses
that were prevalent among us in the early years of the present [nineteenth]
century” illustrates the strength of conviction based on English specimens
as to the root-nature of Stigmaria.
There is undoubtedly considerable confusion, which can be cleared up
only by further research, as to the precise relation between Stigmaria and
Stigmariopsis on the one hand and the different types of Sigillariae on the
other. The main contention, and this is the most important point, of Renault,
Grand’Eury and Solms-Laubach as to the manner of formation of the aerial
shoots from rhizomes and the subsequent production of forked roots and
their ultimate separation from the parent rhizome is, as I believe, correct.
Williamson held that Stigmaria must be regarded as a true root; he found no
evidence to support the view that the large rooted stem discovered by
Hawshaw, Binney, and others had been originally produced from aquatic
rhizomes. It must, however, be remembered that Grand’Eury’s opinion is
based on evidence afforded by the exceptionally well displayed Sigillarian
forests of St Étienne, on a scale such as English strata have not as yet
afforded. Moreover, the absence of any parent-rhizome in association with
the rooted stumps described by Williamson and by others is not a serious
argument against their rhizome origin.
The specimen represented in fig. 209, which was examined in situ by
Solms-Laubach and Grand’Eury, shows a Sigillarian stem in the
Syringodendron condition bearing rows of paired parichnos scars; from the
base forked and rapidly tapering arms radiate through the surrounding rock
and, as shown by other specimens, these bear numerous appendages like
those of the English Stigmarias. The surface-features of the arms are those
of Stigmariopsis and the centre of each, as seen on the broken face, is
occupied by a pith-cast characterised by parallel longitudinal ridges
resembling those on the medullary casts of Calamites. It is noteworthy that
the petrified rhizome originally described by Renault as Stigmaria flexuosa,
and afterwards identified by him as the subterranean system of Sigillaria
Page 273
Brardi, possesses a vascular cylinder composed of primary xylem strands of
crescentic transverse section lining the pith; a cast of the pith, after the
removal by decay of its delicate parenchymatous tissue, would exhibit the
surface-features of Stigmariopsis. Stigmaria flexuosa no doubt represents a
true Stigmariopsis rhizome. On the other hand, as Williamson has shown,
the inner surface of the wood of Stigmaria ficoides consists of a reticulum
of xylem with meshes of medullary-ray tissue; a cast of such a surface
presents a very different appearance from that of Stigmariopsis.
Returning to fig. 209: from the lower surface of the Stigmariopsis arms
numerous conical outgrowths, reaching a length of several centimetres,
project vertically downwards; these also possess Stigmariopsis pith-casts
and are identical with the “tap-roots” of Richard Brown. The stump seen in
fig. 209 shows the characteristic hollow base of the erect stem: this is the
region which, it is believed, represents the position of the Stigmarian
rhizome from which the aerial shoot was developed. Although no remains
of the parent rhizome were found, traces of the rootlets which probably
belonged to it were found in the neighbourhood. The absence of the actual
rhizome is, however, not surprising as it would not persist after its aerial
Sigillarian branches had attained independence by the development of their
own dichotomously branched absorbing and holdfast organs.
The Stigmarian axes of Palaeozoic Lycopods are compared by Miss
Thomas[593] with the prop-roots of certain recent flowering plants which
grow in tropical tidal swamps; their roots grow downwards from the stem at
an angle of 50°-60° before spreading out horizontally. This author also
makes some interesting suggestions in regard to the evidence afforded by
anatomical structure as to the habitat of Sigillaria and Lepidodendron.
Anatomy.
The more important anatomical features of Stigmaria must be dealt with
briefly. Williamson’s monograph, published in 1887[594], is considerably in
advance of the work of that of any of the numerous writers who had
previously dealt with the subject. The diagrammatic transverse section
reproduced in fig. 210, H, illustrates the general arrangement of the tissues.
The medullated stele was described by Williamson as consisting entirely of
centrifugally developed secondary xylem and distinguished, therefore, from
the stele of a Lepidodendron or Sigillaria by the absence of a centripetally
crescentic transverse section lining the pith; a cast of the pith, after the
removal by decay of its delicate parenchymatous tissue, would exhibit the
surface-features of Stigmariopsis. Stigmaria flexuosa no doubt represents a
true Stigmariopsis rhizome. On the other hand, as Williamson has shown,
the inner surface of the wood of Stigmaria ficoides consists of a reticulum
of xylem with meshes of medullary-ray tissue; a cast of such a surface
presents a very different appearance from that of Stigmariopsis.
Returning to fig. 209: from the lower surface of the Stigmariopsis arms
numerous conical outgrowths, reaching a length of several centimetres,
project vertically downwards; these also possess Stigmariopsis pith-casts
and are identical with the “tap-roots” of Richard Brown. The stump seen in
fig. 209 shows the characteristic hollow base of the erect stem: this is the
region which, it is believed, represents the position of the Stigmarian
rhizome from which the aerial shoot was developed. Although no remains
of the parent rhizome were found, traces of the rootlets which probably
belonged to it were found in the neighbourhood. The absence of the actual
rhizome is, however, not surprising as it would not persist after its aerial
Sigillarian branches had attained independence by the development of their
own dichotomously branched absorbing and holdfast organs.
The Stigmarian axes of Palaeozoic Lycopods are compared by Miss
Thomas[593] with the prop-roots of certain recent flowering plants which
grow in tropical tidal swamps; their roots grow downwards from the stem at
an angle of 50°-60° before spreading out horizontally. This author also
makes some interesting suggestions in regard to the evidence afforded by
anatomical structure as to the habitat of Sigillaria and Lepidodendron.
Anatomy.
The more important anatomical features of Stigmaria must be dealt with
briefly. Williamson’s monograph, published in 1887[594], is considerably in
advance of the work of that of any of the numerous writers who had
previously dealt with the subject. The diagrammatic transverse section
reproduced in fig. 210, H, illustrates the general arrangement of the tissues.
The medullated stele was described by Williamson as consisting entirely of
centrifugally developed secondary xylem and distinguished, therefore, from
the stele of a Lepidodendron or Sigillaria by the absence of a centripetally
Page 274
produced primary xylem zone. The secondary xylem tracheae are
characterised by scalariform pits on both radial and tangential walls and, as
shown in a figure given by Solms-Laubach[595], the spaces between the
transverse bars are bridged across by fine threads, as in the tracheae of
Lepidodendron.
One of the largest specimens of a petrified Stigmaria which I have seen is
one lent to me by Mr Lomax from the Coal-Measures of Halifax in which
the flattened transverse section measures 18 cm. × 3·5 cm., the cylinder of
wood being 1·1 cm. × 7 mm. in diameter.
In French examples of Stigmaria or Stigmariopsis it has been
demonstrated by Renault[596] that primary xylem strands occur very like
those in the stem of some species of Sigillariae (see p. 219). If a well-
preserved section of an English Stigmaria is examined it will be seen that
the edge of the secondary wood consists of a few narrower elements which
do not exhibit the radial seriation characteristic of secondary elements.
A type of Stigmaria characterised by centripetal primary wood has been
described by Weiss[597] and referred by him to Bothrodendron mundum; the
main results of his observations are stated in the account of Bothrodendron
on a subsequent page. This discovery is of considerable interest not only as
rendering our knowledge of Bothrodendron remarkably complete but as
confirmatory of Renault’s account of French Stigmarian axes in which
centripetal primary wood is well developed between the secondary xylem
and the centre of the stele. The Stigmarian axis of Bothrodendron was
originally figured by Williamson as Lepidodendron mundum[598]. The chief
difference between Weiss’s specimen and those described by Renault[599] as
the Stigmarian axes of Sigillaria Brardi, is that in the English plant the
centripetal wood forms a cylinder of uniform breadth instead of a band with
a crenulated inner margin as figured by Renault.
STIGMARIA
characterised by scalariform pits on both radial and tangential walls and, as
shown in a figure given by Solms-Laubach[595], the spaces between the
transverse bars are bridged across by fine threads, as in the tracheae of
Lepidodendron.
One of the largest specimens of a petrified Stigmaria which I have seen is
one lent to me by Mr Lomax from the Coal-Measures of Halifax in which
the flattened transverse section measures 18 cm. × 3·5 cm., the cylinder of
wood being 1·1 cm. × 7 mm. in diameter.
In French examples of Stigmaria or Stigmariopsis it has been
demonstrated by Renault[596] that primary xylem strands occur very like
those in the stem of some species of Sigillariae (see p. 219). If a well-
preserved section of an English Stigmaria is examined it will be seen that
the edge of the secondary wood consists of a few narrower elements which
do not exhibit the radial seriation characteristic of secondary elements.
A type of Stigmaria characterised by centripetal primary wood has been
described by Weiss[597] and referred by him to Bothrodendron mundum; the
main results of his observations are stated in the account of Bothrodendron
on a subsequent page. This discovery is of considerable interest not only as
rendering our knowledge of Bothrodendron remarkably complete but as
confirmatory of Renault’s account of French Stigmarian axes in which
centripetal primary wood is well developed between the secondary xylem
and the centre of the stele. The Stigmarian axis of Bothrodendron was
originally figured by Williamson as Lepidodendron mundum[598]. The chief
difference between Weiss’s specimen and those described by Renault[599] as
the Stigmarian axes of Sigillaria Brardi, is that in the English plant the
centripetal wood forms a cylinder of uniform breadth instead of a band with
a crenulated inner margin as figured by Renault.
STIGMARIA
Page 275
Fig. 210. Stigmaria.
A. Transverse section of vascular bundle of rootlet and part of outer cortex. t, tracheae.
(After F. E. Weiss.)
B, C. Vascular bundle of rootlet; in C a series of small tracheae are shown extending from
the protoxylem.
D. Rootlets from the outer cortex of E.
E. Part of a large Stigmaria: St, stele; s, intruded rootlet.
F. Vascular bundle and tracheae passing obliquely towards the outer cortex, c3.
G. Outer cortex of Stigmaria.
H. Diagrammatic section of Stigmaria: p, phelloderm; r, rootlets.
An interesting agreement between the French and English specimens is
the occurrence in the cortex of groups of reticulate elements: in Weiss’s
section these are short and wide and occur in the middle cortex; in Renault’s
plant they are more fusiform and occur in the secondary cortical tissue.
These elements appear to have been arranged as an interlacing network in
the middle cortex and were in close connexion with the rootlet-bundles,
A. Transverse section of vascular bundle of rootlet and part of outer cortex. t, tracheae.
(After F. E. Weiss.)
B, C. Vascular bundle of rootlet; in C a series of small tracheae are shown extending from
the protoxylem.
D. Rootlets from the outer cortex of E.
E. Part of a large Stigmaria: St, stele; s, intruded rootlet.
F. Vascular bundle and tracheae passing obliquely towards the outer cortex, c3.
G. Outer cortex of Stigmaria.
H. Diagrammatic section of Stigmaria: p, phelloderm; r, rootlets.
An interesting agreement between the French and English specimens is
the occurrence in the cortex of groups of reticulate elements: in Weiss’s
section these are short and wide and occur in the middle cortex; in Renault’s
plant they are more fusiform and occur in the secondary cortical tissue.
These elements appear to have been arranged as an interlacing network in
the middle cortex and were in close connexion with the rootlet-bundles,
Page 276
comparable, as Weiss points out, with the transfusion tracheids
accompanying Lepidodendron leaf-traces.
It is probable that these short and wide tracheal elements served for
water-storage and thus afford another indication of the xerophilous
character of the Carboniferous Lycopods, a feature possibly connected with
a salt-marsh habitat.
The presence of conspicuous medullary rays gives the secondary xylem
of Stigmaria the appearance of being divided into several more or less
distinct groups (fig. 210, E, St). In tangential longitudinal section the xylem
assumes the form of a broad reticulum with lenticular meshes filled with
medullary-ray tissue through which strands of xylem are cut across in a
transverse direction as they pass outwards from the inner edge of the wood
to supply the rootlets. In addition to these broader or primary medullary
rays, there were numerous secondary rays composed of narrow plates of
parenchymatous cells one or several elements in depth. As Williamson
pointed out, the medullary-ray tissue consists in part of radially elongated
tracheal elements with spiral or scalariform thickening bands like those
described in the same position in Lepidodendron stems.
Our knowledge of the minute structure of the tissues abutting on the
secondary xylem is far from complete.
The xylem is succeeded by a zone of delicate cells which was the seat of
meristematic activity. It is noteworthy that in a section figured by
Williamson[600] there is the same disparity in size between the outermost
elements of the xylem and the adjacent cells of the meristematic zone as in
Lepidodendron stems. Beyond this region an imperfectly preserved lacunar
tissue occurs like that which I have called the secretory zone in
Lepidodendron stems; but information as to the structure of this part of
Stigmaria is much more incomplete than in the case of the aerial shoots.
The middle cortex was of the same lacunar type as in the stems, and the fact
that it is never well preserved in large Stigmarian axes suggests that it may
have been even more richly supplied than in the aerial stems with an
aerating system of spaces. The outer cortex, consisting in young examples
of large-celled parenchyma, became at an early stage of growth the seat of
cambial activity which resulted in the production of radially placed series of
secondary elements (fig. 210, H, p). The outer and older elements of this
accompanying Lepidodendron leaf-traces.
It is probable that these short and wide tracheal elements served for
water-storage and thus afford another indication of the xerophilous
character of the Carboniferous Lycopods, a feature possibly connected with
a salt-marsh habitat.
The presence of conspicuous medullary rays gives the secondary xylem
of Stigmaria the appearance of being divided into several more or less
distinct groups (fig. 210, E, St). In tangential longitudinal section the xylem
assumes the form of a broad reticulum with lenticular meshes filled with
medullary-ray tissue through which strands of xylem are cut across in a
transverse direction as they pass outwards from the inner edge of the wood
to supply the rootlets. In addition to these broader or primary medullary
rays, there were numerous secondary rays composed of narrow plates of
parenchymatous cells one or several elements in depth. As Williamson
pointed out, the medullary-ray tissue consists in part of radially elongated
tracheal elements with spiral or scalariform thickening bands like those
described in the same position in Lepidodendron stems.
Our knowledge of the minute structure of the tissues abutting on the
secondary xylem is far from complete.
The xylem is succeeded by a zone of delicate cells which was the seat of
meristematic activity. It is noteworthy that in a section figured by
Williamson[600] there is the same disparity in size between the outermost
elements of the xylem and the adjacent cells of the meristematic zone as in
Lepidodendron stems. Beyond this region an imperfectly preserved lacunar
tissue occurs like that which I have called the secretory zone in
Lepidodendron stems; but information as to the structure of this part of
Stigmaria is much more incomplete than in the case of the aerial shoots.
The middle cortex was of the same lacunar type as in the stems, and the fact
that it is never well preserved in large Stigmarian axes suggests that it may
have been even more richly supplied than in the aerial stems with an
aerating system of spaces. The outer cortex, consisting in young examples
of large-celled parenchyma, became at an early stage of growth the seat of
cambial activity which resulted in the production of radially placed series of
secondary elements (fig. 210, H, p). The outer and older elements of this
Page 277
secondary cortex are more tangentially stretched than the inner cells, a
necessary result of the position of the phellogen on the internal edge of the
tissue and of the increasing girth of the axis.
In comparatively young Stigmarian axes the outer cortex already
possesses a band of secondary radially disposed cells characterised by the
greater tangential extension of the more external elements; usually this
tissue terminates abruptly on the inner edge and the line of separation no
doubt marks the position of the phellogen. Occasionally some delicate
secondary elements are preserved internal to the phellogen, and these in
young specimens form a narrow cylinder composed in part of radially
elongated cells showing signs of recent tangential divisions. In its earlier
stage of activity the phellogen seems to form a greater amount of secondary
tissue on the outside, but this is clearly not of the nature of cork, the tissue
which occupies a corresponding position in recent plants. The primary
cortex shows no signs of shrinkage or collapse as would be the case were it
cut off from the vascular system by a zone of impermeable cork.
Fig. 210, G, represents a piece of the external tissue of a specimen in
which the slightly flattened xylem cylinder measures 1·4 × 1 cm.; the inner
cortex has disappeared and fragments only of the middle cortex are
preserved. The outer cortex, with an average breadth of 2 mm., consists
superficially of primary parenchyma with a somewhat uneven surface and
with a rootlet attached here and there; a short distance below the surface is a
band of conspicuous cells, b, characterised by dark contents suggesting very
imperfectly preserved fungal hyphae, but the nature of the substance filling
the cells cannot be made out with certainty. It is, however, interesting to
find that this dark band constitutes an obvious feature (fig. 210 H, b); its
position is comparable with that of the dark-walled cells in the outer cortex
of rootlets. A short distance internal to this dark band tangentially elongated
cells form the outermost elements of the secondary cortex; these become
gradually narrower towards the interior and pass into radial series of smaller
cells of uniform size, as seen on the inner edge of fig. 210, G. At the inner
boundary of this tissue, just below the region shown at the bottom of the
drawing, was situated the phellogen. Such traces of tissue as occur on the
inner side of the line where splitting has usually occurred, consist of thinner
elements with recently formed tangential walls and probably represent an
early stage in the development of phelloderm.
necessary result of the position of the phellogen on the internal edge of the
tissue and of the increasing girth of the axis.
In comparatively young Stigmarian axes the outer cortex already
possesses a band of secondary radially disposed cells characterised by the
greater tangential extension of the more external elements; usually this
tissue terminates abruptly on the inner edge and the line of separation no
doubt marks the position of the phellogen. Occasionally some delicate
secondary elements are preserved internal to the phellogen, and these in
young specimens form a narrow cylinder composed in part of radially
elongated cells showing signs of recent tangential divisions. In its earlier
stage of activity the phellogen seems to form a greater amount of secondary
tissue on the outside, but this is clearly not of the nature of cork, the tissue
which occupies a corresponding position in recent plants. The primary
cortex shows no signs of shrinkage or collapse as would be the case were it
cut off from the vascular system by a zone of impermeable cork.
Fig. 210, G, represents a piece of the external tissue of a specimen in
which the slightly flattened xylem cylinder measures 1·4 × 1 cm.; the inner
cortex has disappeared and fragments only of the middle cortex are
preserved. The outer cortex, with an average breadth of 2 mm., consists
superficially of primary parenchyma with a somewhat uneven surface and
with a rootlet attached here and there; a short distance below the surface is a
band of conspicuous cells, b, characterised by dark contents suggesting very
imperfectly preserved fungal hyphae, but the nature of the substance filling
the cells cannot be made out with certainty. It is, however, interesting to
find that this dark band constitutes an obvious feature (fig. 210 H, b); its
position is comparable with that of the dark-walled cells in the outer cortex
of rootlets. A short distance internal to this dark band tangentially elongated
cells form the outermost elements of the secondary cortex; these become
gradually narrower towards the interior and pass into radial series of smaller
cells of uniform size, as seen on the inner edge of fig. 210, G. At the inner
boundary of this tissue, just below the region shown at the bottom of the
drawing, was situated the phellogen. Such traces of tissue as occur on the
inner side of the line where splitting has usually occurred, consist of thinner
elements with recently formed tangential walls and probably represent an
early stage in the development of phelloderm.
Page 278
A much older section is shown in part in fig. 210, E. The secondary
xylem cylinder, St, is shown in the lower part of the section; beyond this is
a band of secondary tissue which reaches in some places a breadth of 6 cm.
The greater part of this tissue consists of phelloderm of very uniform
structure made up of radial series of cells: this is interrupted in most parts of
the section by a gap crowded with intruded rootlets (a portion of this is
enlarged in fig. 210, D). Beyond this gap the secondary tissue consists of
radial series of cells characterised by the considerable tangential elongation
of many of the elements, precisely like the tissue figured by Williamson. In
all probability the gap represents a line of weakness due to the phellogen,
and if this is the case it is clear that in an old Stigmaria the phelloderm
exceeded in amount the tissue formed external to the phellogen. The
secondary tissue on the inner side of the phellogen is characterised by
numerous irregular concentric lines superficially resembling rings of
growth in the wood of a Conifer: these are, however, not the result of any
periodic change in external conditions, but are apparently due to crushing of
the tissue and are possibly, to some extent, the result of the presence of
secretory strands like those in the phelloderm of Lepidodendron. The
surface of this older rhizome retains patches of primary tissue, and an
occasional rootlet, as at r, fig. 210, E, is seen in connexion with the cortex;
the cortex has been vertically fissured as the result of secondary growth and
presents an appearance like that shown in Lepidodendron Wünschianum
and L. Veltheimianum (figs. 181, A, and 186, A).
The form in which a Stigmarian rootlet is usually preserved is shown in
fig. 210, D; the single vascular bundle strand with its endarch protoxylem
(fig. 210, B, px) is enclosed by a ring of inner cortical parenchyma (fig.
210, F, c1); the cells in immediate contact with the xylem having usually
disappeared. Beyond the middle cortical space a second cylinder of
parenchyma represents the outer cortex (F, c3) in which a layer of dark-
walled cells (b, fig. 210, F) may be compared with the hypodermal band in
the main Stigmarian axis (G, b). These Stigmarian rootlets, usually less than
1 cm. in diameter, are the commonest objects in sections of the calcareous
nodules from English coal-seams. A good example of their abundance is
shown in fig. 210, D and E; here they have invaded the space formed by the
splitting of the secondary cortical tissues along the line of the phellogen and
a few are seen here and there in the deeper layers of the phelloderm (s, fig.
210, E). Not infrequently the close contact of these ubiquitous rootlets with
xylem cylinder, St, is shown in the lower part of the section; beyond this is
a band of secondary tissue which reaches in some places a breadth of 6 cm.
The greater part of this tissue consists of phelloderm of very uniform
structure made up of radial series of cells: this is interrupted in most parts of
the section by a gap crowded with intruded rootlets (a portion of this is
enlarged in fig. 210, D). Beyond this gap the secondary tissue consists of
radial series of cells characterised by the considerable tangential elongation
of many of the elements, precisely like the tissue figured by Williamson. In
all probability the gap represents a line of weakness due to the phellogen,
and if this is the case it is clear that in an old Stigmaria the phelloderm
exceeded in amount the tissue formed external to the phellogen. The
secondary tissue on the inner side of the phellogen is characterised by
numerous irregular concentric lines superficially resembling rings of
growth in the wood of a Conifer: these are, however, not the result of any
periodic change in external conditions, but are apparently due to crushing of
the tissue and are possibly, to some extent, the result of the presence of
secretory strands like those in the phelloderm of Lepidodendron. The
surface of this older rhizome retains patches of primary tissue, and an
occasional rootlet, as at r, fig. 210, E, is seen in connexion with the cortex;
the cortex has been vertically fissured as the result of secondary growth and
presents an appearance like that shown in Lepidodendron Wünschianum
and L. Veltheimianum (figs. 181, A, and 186, A).
The form in which a Stigmarian rootlet is usually preserved is shown in
fig. 210, D; the single vascular bundle strand with its endarch protoxylem
(fig. 210, B, px) is enclosed by a ring of inner cortical parenchyma (fig.
210, F, c1); the cells in immediate contact with the xylem having usually
disappeared. Beyond the middle cortical space a second cylinder of
parenchyma represents the outer cortex (F, c3) in which a layer of dark-
walled cells (b, fig. 210, F) may be compared with the hypodermal band in
the main Stigmarian axis (G, b). These Stigmarian rootlets, usually less than
1 cm. in diameter, are the commonest objects in sections of the calcareous
nodules from English coal-seams. A good example of their abundance is
shown in fig. 210, D and E; here they have invaded the space formed by the
splitting of the secondary cortical tissues along the line of the phellogen and
a few are seen here and there in the deeper layers of the phelloderm (s, fig.
210, E). Not infrequently the close contact of these ubiquitous rootlets with
Page 279
the tissues of the plant which they have invaded leads to confusion between
invader and invaded. Partially decayed tissues lying, probably, under water
were penetrated by Stigmarian rootlets in exactly the same way as the roots
of recent plants bore through vegetable substances which happen to be in
their path. The rootlet bundles are in the first instance composed of the
primary tracheae which line the inner edge of the secondary xylem; these
receive additions from the meristematic zone, and thus, when seen in the
cortex outside the stelar region, are found to consist in part of primary and
in part of a fan-shaped group of secondary tracheae. On the other hand, the
monarch bundle as it appears in a free rootlet is usually composed entirely
of primary elements (fig. 210, A–C, F). It has been shown by Weiss[601] that
in the Stigmarian rhizome of what is probably Lepidodendron fuliginosum,
the rootlet bundle is accompanied by a parichnos strand, but this has not
been detected in the ordinary Stigmaria ficoides. When free from the parent
axis a rootlet usually consists of an outer cylinder of cortex enclosing a
broad space in which remnants of lacunar tissue are sometimes seen. The
relation of the external features of a well-preserved Stigmarian rootlet-scar
to the internal structure of a petrified rootlet is very clearly seen on
comparing such sections as those represented in fig. 210, D, with the form
of the scar on a Stigmarian cast. A specimen figured by Hooker[602] in 1848
affords a good illustration of the structure of a rootlet-base as seen in an
unusually complete cast; this correlation of anatomical and surface features
is clearly described also by Williamson[603] and by Solms-Laubach[604]. It is
probable that even during life the rootlets were hollow for a part at least of
their length as are the roots of Isoetes (fig. 133, G).
An interesting discovery was made a few years ago which confirmed a
statement by Renault which Williamson was unable to accept, namely that
the xylem bundle of a rootlet occasionally gives off a delicate tracheal
strand at right angles to the long axis of a rootlet. In some rootlets Weiss[605]
found obliquely running delicate strands of xylem, surrounded by a layer of
parenchymatous tissue, in the space between the vascular bundle and the
outer cortical cylinder. It is clear that a few spiral tracheids are occasionally
given off from the protoxylem of a rootlet bundle: these follow an oblique
course to the outer cortex, where in some cases they have been traced into
connexion with short and spirally marked cells resembling transfusion
tracheae (fig. 210, A). This arrangement may serve as a means of
facilitating the passage of water absorbed by the superficial cells into the
invader and invaded. Partially decayed tissues lying, probably, under water
were penetrated by Stigmarian rootlets in exactly the same way as the roots
of recent plants bore through vegetable substances which happen to be in
their path. The rootlet bundles are in the first instance composed of the
primary tracheae which line the inner edge of the secondary xylem; these
receive additions from the meristematic zone, and thus, when seen in the
cortex outside the stelar region, are found to consist in part of primary and
in part of a fan-shaped group of secondary tracheae. On the other hand, the
monarch bundle as it appears in a free rootlet is usually composed entirely
of primary elements (fig. 210, A–C, F). It has been shown by Weiss[601] that
in the Stigmarian rhizome of what is probably Lepidodendron fuliginosum,
the rootlet bundle is accompanied by a parichnos strand, but this has not
been detected in the ordinary Stigmaria ficoides. When free from the parent
axis a rootlet usually consists of an outer cylinder of cortex enclosing a
broad space in which remnants of lacunar tissue are sometimes seen. The
relation of the external features of a well-preserved Stigmarian rootlet-scar
to the internal structure of a petrified rootlet is very clearly seen on
comparing such sections as those represented in fig. 210, D, with the form
of the scar on a Stigmarian cast. A specimen figured by Hooker[602] in 1848
affords a good illustration of the structure of a rootlet-base as seen in an
unusually complete cast; this correlation of anatomical and surface features
is clearly described also by Williamson[603] and by Solms-Laubach[604]. It is
probable that even during life the rootlets were hollow for a part at least of
their length as are the roots of Isoetes (fig. 133, G).
An interesting discovery was made a few years ago which confirmed a
statement by Renault which Williamson was unable to accept, namely that
the xylem bundle of a rootlet occasionally gives off a delicate tracheal
strand at right angles to the long axis of a rootlet. In some rootlets Weiss[605]
found obliquely running delicate strands of xylem, surrounded by a layer of
parenchymatous tissue, in the space between the vascular bundle and the
outer cortical cylinder. It is clear that a few spiral tracheids are occasionally
given off from the protoxylem of a rootlet bundle: these follow an oblique
course to the outer cortex, where in some cases they have been traced into
connexion with short and spirally marked cells resembling transfusion
tracheae (fig. 210, A). This arrangement may serve as a means of
facilitating the passage of water absorbed by the superficial cells into the
Page 280
xylem strand. It should be noticed that, like roots of recent water-plants, the
rootlets of Stigmaria had no root-hairs. Fig. 210, F, shows a transverse
section of part of a rootlet in which the outer cortical cylinder, c3, is
connected, as in the roots of Isoetes, with the sheath surrounding the
vascular bundle. A few obliquely cut tracheae are seen in this section
traversing the connecting band of parenchyma t, fig. 210, A.
A point of biological interest in connexion with Stigmaria rootlets is the
occasional presence of hypertrophied cells, the large size of which is due to
the attacks of a fungus named by Weiss[606] Urophlyctites stigmariae.
In addition to Stigmaria ficoides, which is by far the commonest form, a
few other species have been founded on external characters. One of these is
represented by Stigmaria stellata, Goepp.[607], characterised by the presence
of radially disposed ridges and small tubercles surrounding each rootlet-
scar. Kidston refers to Goeppert’s species as a Lower Carboniferous type.
We have no evidence as to the meaning of the stellate ridges and tubercles,
nor have we any reason to suppose that this form differed essentially in
structure from Stigmaria ficoides.
rootlets of Stigmaria had no root-hairs. Fig. 210, F, shows a transverse
section of part of a rootlet in which the outer cortical cylinder, c3, is
connected, as in the roots of Isoetes, with the sheath surrounding the
vascular bundle. A few obliquely cut tracheae are seen in this section
traversing the connecting band of parenchyma t, fig. 210, A.
A point of biological interest in connexion with Stigmaria rootlets is the
occasional presence of hypertrophied cells, the large size of which is due to
the attacks of a fungus named by Weiss[606] Urophlyctites stigmariae.
In addition to Stigmaria ficoides, which is by far the commonest form, a
few other species have been founded on external characters. One of these is
represented by Stigmaria stellata, Goepp.[607], characterised by the presence
of radially disposed ridges and small tubercles surrounding each rootlet-
scar. Kidston refers to Goeppert’s species as a Lower Carboniferous type.
We have no evidence as to the meaning of the stellate ridges and tubercles,
nor have we any reason to suppose that this form differed essentially in
structure from Stigmaria ficoides.
Page 281
Page 282
CHAPTER XVIII.
Bothrodendreae.
Bothrodendron. Figs. 211–216.
Although in many respects the genus Bothrodendron agrees very closely
in habit and in its anatomical features with Lepidodendron, there are
reasons for referring it to a distinct family of Palaeozoic Lycopods. As the
following description shows, the external features do not differ in any
essential points from those of certain types of the genus Sigillaria,
particularly such a species as S. rimosa, Gold.[608], which has recently been
refigured and described by Nathorst[609] from Goldenberg’s type-specimen
in the Stockholm Museum. The small size of the leaf-scars is, however, a
characteristic feature of Bothrodendron (fig. 212, F); but a more important
point is the fact that in a recently described[610] English example of a cone of
Bothrodendron (fig. 216), the sporangia are very like those of recent
Lycopods, and differ from the radially elongated sporangia of
Lepidostrobus. On the other hand, a French cone described by Zeiller[611] as
Lepidostrobus Olryi, which is probably a strobilus of Bothrodendron, has
the radially elongated type of sporangium (fig. 212, E). The comparative
abundance of Bothrodendron in Lower Carboniferous and Devonian rocks
points to the greater antiquity of this member of the Lycopodiales as
compared with Lepidodendron.
The name Bothrodendron was instituted by Lindley and Hutton[612] for
impressions of stems from the English Coal-Measures, characterised by two
opposite rows of large depressions like those shown in fig. 211 and, in one
of the specimens, by “a considerable number of minute dots, arranged in a
quincuncial manner.” The minute dots were recognised as leaf-scars and the
cup-like cavities were described as probably connected with the occurrence
of large cones. On very slender evidence this Palaeozoic plant, which was
named Bothrodendron punctatum, was considered by these authors as
Bothrodendreae.
Bothrodendron. Figs. 211–216.
Although in many respects the genus Bothrodendron agrees very closely
in habit and in its anatomical features with Lepidodendron, there are
reasons for referring it to a distinct family of Palaeozoic Lycopods. As the
following description shows, the external features do not differ in any
essential points from those of certain types of the genus Sigillaria,
particularly such a species as S. rimosa, Gold.[608], which has recently been
refigured and described by Nathorst[609] from Goldenberg’s type-specimen
in the Stockholm Museum. The small size of the leaf-scars is, however, a
characteristic feature of Bothrodendron (fig. 212, F); but a more important
point is the fact that in a recently described[610] English example of a cone of
Bothrodendron (fig. 216), the sporangia are very like those of recent
Lycopods, and differ from the radially elongated sporangia of
Lepidostrobus. On the other hand, a French cone described by Zeiller[611] as
Lepidostrobus Olryi, which is probably a strobilus of Bothrodendron, has
the radially elongated type of sporangium (fig. 212, E). The comparative
abundance of Bothrodendron in Lower Carboniferous and Devonian rocks
points to the greater antiquity of this member of the Lycopodiales as
compared with Lepidodendron.
The name Bothrodendron was instituted by Lindley and Hutton[612] for
impressions of stems from the English Coal-Measures, characterised by two
opposite rows of large depressions like those shown in fig. 211 and, in one
of the specimens, by “a considerable number of minute dots, arranged in a
quincuncial manner.” The minute dots were recognised as leaf-scars and the
cup-like cavities were described as probably connected with the occurrence
of large cones. On very slender evidence this Palaeozoic plant, which was
named Bothrodendron punctatum, was considered by these authors as
Page 283
probably a member of the Coniferales. The large stem from the Coal-
Measures in the neighbourhood of Mons, Belgium, shown in fig. 211,
affords a good illustration of Bothrodendron in a partially decorticated
condition, exhibiting a row of depressions similar to those on the
Ulodendron form of Lepidodendron Veltheimianum (fig. 157), but
distinguished by the eccentric position of the scar at the bottom of each cup-
shaped cavity: in the Belgian specimen, which is partially decorticated and
shows the leaf-traces as small dots, the depressions have a diameter of 9
cm. It is believed by some authors that these Ulodendron shoots of
Bothrodendron and Lepidodendron owe their characteristic appearance to
the pressure of large cones, but, as I have already stated, there are reasons
for preferring the view that these crater-like hollows are the scars of
deciduous branches. Our knowledge of the strobili borne by Bothrodendron
stems is still meagre, but we have no reason to assume the existence of any
cones large enough to produce by the pressure of their bases such
depressions as those shown in fig. 211. In one species at least the strobili
were borne terminally on slender shoots (fig. 213). The Ulodendron
condition has so far been recognised in one species only, B. punctatum.
In his catalogue of Palaeozoic plants, Kidston[613] included
Bothrodendron punctatum as a synonym of Sigillaria discophora König, a
mistake which he afterwards rectified[614]: the generic name Bothrodendron
was generally ignored by authors in the belief that the specimens described
by Lindley and Hutton were not generically distinct from the fossils
originally figured by Rhode as Ulodendron. It was Prof. Zeiller who first
demonstrated that the English authors were justified in their choice of a new
designation for stems with large depressions in association with minute
leaf-scars. In 1859 Haughton[615] proposed a new family name
Cyclostigmaceae for some Upper Devonian plants from County Kilkenny,
Ireland: he described three species of his new genus Cyclostigma,
Cyclostigma kiltorkense, C. minutum, and C. Griffithsi; these are now
generally recognised as a single species of Bothrodendron, though, as
Nathorst suggests, the Irish plant should perhaps be separated as a sub-
genus Bothrodendron (Cyclostigma) by reason of certain minor differences
which distinguish it from other species of the genus.
Measures in the neighbourhood of Mons, Belgium, shown in fig. 211,
affords a good illustration of Bothrodendron in a partially decorticated
condition, exhibiting a row of depressions similar to those on the
Ulodendron form of Lepidodendron Veltheimianum (fig. 157), but
distinguished by the eccentric position of the scar at the bottom of each cup-
shaped cavity: in the Belgian specimen, which is partially decorticated and
shows the leaf-traces as small dots, the depressions have a diameter of 9
cm. It is believed by some authors that these Ulodendron shoots of
Bothrodendron and Lepidodendron owe their characteristic appearance to
the pressure of large cones, but, as I have already stated, there are reasons
for preferring the view that these crater-like hollows are the scars of
deciduous branches. Our knowledge of the strobili borne by Bothrodendron
stems is still meagre, but we have no reason to assume the existence of any
cones large enough to produce by the pressure of their bases such
depressions as those shown in fig. 211. In one species at least the strobili
were borne terminally on slender shoots (fig. 213). The Ulodendron
condition has so far been recognised in one species only, B. punctatum.
In his catalogue of Palaeozoic plants, Kidston[613] included
Bothrodendron punctatum as a synonym of Sigillaria discophora König, a
mistake which he afterwards rectified[614]: the generic name Bothrodendron
was generally ignored by authors in the belief that the specimens described
by Lindley and Hutton were not generically distinct from the fossils
originally figured by Rhode as Ulodendron. It was Prof. Zeiller who first
demonstrated that the English authors were justified in their choice of a new
designation for stems with large depressions in association with minute
leaf-scars. In 1859 Haughton[615] proposed a new family name
Cyclostigmaceae for some Upper Devonian plants from County Kilkenny,
Ireland: he described three species of his new genus Cyclostigma,
Cyclostigma kiltorkense, C. minutum, and C. Griffithsi; these are now
generally recognised as a single species of Bothrodendron, though, as
Nathorst suggests, the Irish plant should perhaps be separated as a sub-
genus Bothrodendron (Cyclostigma) by reason of certain minor differences
which distinguish it from other species of the genus.
Page 284
Fig. 211. Bothrodendron punctatum. Part of a specimen from near Mons (Hainaut), in the
Brussels Museum. (Reduced.)
Another generic name, Rhytidodendron, was instituted by Boulay in 1876
for stems characterised by a finely wrinkled bark and small spirally
disposed leaf-scars. A short description of this type, which occurs in the
Middle and Lower Coal-Measures, may serve to illustrate the external
features of the commonest British example of the genus.
a. Bothrodendron minutifolium (Boulay.) Figs. 212, A, C, D; 213.
Brussels Museum. (Reduced.)
Another generic name, Rhytidodendron, was instituted by Boulay in 1876
for stems characterised by a finely wrinkled bark and small spirally
disposed leaf-scars. A short description of this type, which occurs in the
Middle and Lower Coal-Measures, may serve to illustrate the external
features of the commonest British example of the genus.
a. Bothrodendron minutifolium (Boulay.) Figs. 212, A, C, D; 213.
Page 285
1875. Lycopodium carbonaceum (Lycopodites carbonaceus),
Feistmantel, Palaeontographica xxxiii., Pl. xxx. figs. 1, 2; p.
183.
1876. Rhytidodendron minutifolium, Boulay, Terr. Houill. Nord
France, p. 39, Pl. iii. fig. 1.
1886. Bothrodendron minutifolium, Zeiller, Bull. Soc. Géol. France
[iii] xiv. p. 176, Pl. ix. figs. 1, 2.
1888. Lepidostrobus Olryi, Zeiller, Flor. Valenciennes, p. 502, Pl.
lxxvii. fig. 1.
1889. Bothrodendron minutifolium, Kidston, Trans. R. Soc.
Edinburgh, Vol. xxxv. Pt. ii.
1893. Sigillaria (Bothrodendron) minutifolia, Weiss and Sterzel, K.
Preuss. Geol. Landesanstalt, Heft 2, p. 49, Pl. i. figs. 3 and 4;
Pl. ii. figs. 8 and 9.
1904. Bothrodendron minutifolium, Zalessky, Mém. Com. Géol.
Russie, Pl. vi. fig. 6.
Feistmantel, Palaeontographica xxxiii., Pl. xxx. figs. 1, 2; p.
183.
1876. Rhytidodendron minutifolium, Boulay, Terr. Houill. Nord
France, p. 39, Pl. iii. fig. 1.
1886. Bothrodendron minutifolium, Zeiller, Bull. Soc. Géol. France
[iii] xiv. p. 176, Pl. ix. figs. 1, 2.
1888. Lepidostrobus Olryi, Zeiller, Flor. Valenciennes, p. 502, Pl.
lxxvii. fig. 1.
1889. Bothrodendron minutifolium, Kidston, Trans. R. Soc.
Edinburgh, Vol. xxxv. Pt. ii.
1893. Sigillaria (Bothrodendron) minutifolia, Weiss and Sterzel, K.
Preuss. Geol. Landesanstalt, Heft 2, p. 49, Pl. i. figs. 3 and 4;
Pl. ii. figs. 8 and 9.
1904. Bothrodendron minutifolium, Zalessky, Mém. Com. Géol.
Russie, Pl. vi. fig. 6.
Page 286
Fig. 212. Bothrodendron.
A. Bothrodendron minutifolium, var. rotundata Weiss. After Weiss and Sterzel.
B. B. punctatum. After Zeiller.
C. B. minutifolium. After Weiss and Sterzel.
D. B. minutifolium. After Zeiller.
E. Lepidostrobus Olryi. After Zeiller.
F. Bothrodendron punctatum. After Zeiller.
G, H. B. kiltorkense. G, after Nathorst; H, after Weiss and Sterzel.
In habit a plant of Bothrodendron recalls Lepidodendron and recent
species of Lycopodium; the slender dichotomously branched twigs bearing
numerous leaves (fig. 212, D), have been mistaken for shoots of
A. Bothrodendron minutifolium, var. rotundata Weiss. After Weiss and Sterzel.
B. B. punctatum. After Zeiller.
C. B. minutifolium. After Weiss and Sterzel.
D. B. minutifolium. After Zeiller.
E. Lepidostrobus Olryi. After Zeiller.
F. Bothrodendron punctatum. After Zeiller.
G, H. B. kiltorkense. G, after Nathorst; H, after Weiss and Sterzel.
In habit a plant of Bothrodendron recalls Lepidodendron and recent
species of Lycopodium; the slender dichotomously branched twigs bearing
numerous leaves (fig. 212, D), have been mistaken for shoots of
Page 287
Lycopodium, and fragments of branches might well be identified as
impressions of Mosses. The leaf-scars on the smaller shoots occur on
elongated cushions (fig. 212, C, D) with a transversely wrinkled surface; on
the older branches the leaf-scars are separated by fairly large areas of bark
characterised by sinuous transverse grooves and narrow ridges bearing
numerous small pits, as shown on an enlarged scale in fig. 212, A. The
original surface-features are shown on the left of the drawing, and a slightly
deeper level in the cortex is represented on the right-hand side. The absence
of leaf-cushions on the older shoots is probably the result of secondary
thickening, which also alters the size and shape of the leaf-scars. Each scar
has three pits on its surface, as in Lepidodendron; a central leaf-trace scar
and lateral parichnos scars. The circular pit above the leaf-scars, which
occurs in most species, marks the position of the ligule. The relation of the
short leaves, 5 mm. long, to the leaf-cushions is shown in fig. 212, D. The
absence of leaves, except in impressions of slender twigs, may be
interpreted as an indication that they were shed at an early stage and did not
persist many years. The leaf-cushions of the smaller shoots of
Bothrodendron minutifolium closely resemble those figured by Weiss on a
Devonian plant, Lepidodendron Losseni[616].
One of the few examples so far discovered of a Bothrodendron cone is
shown in fig. 213; this specimen, at least 10 cm. long, was found by Mr
Hemingway in the Middle Coal-Measures of Yorkshire and described by Dr
Kidston. Numerous sporophylls are attached at right angles to the axis, the
surface of which is protected by their upturned distal portions; the
arrangement of the parts appears to be the same as in Lepidostrobus. A
specimen figured by Zeiller as Lepidostrobus Olryi, which Kidston is
probably correct in identifying with Bothrodendron minutifolium, shows
that each sporophyll carries a horizontally elongated sporangium (fig. 212,
E).
b. Bothrodendron punctatum Lindley and Hutton[617]. Figs. 211, 212 B, F.
This species, which is less abundant than B. minutifolium, in British
Coal-Measures, has been described by several authors as Ulodendron on
account of the occurrence of large depressions, like those shown in fig. 211,
on certain branches of the plant. At the suggestion of Dr Kidston, Prof.
Zeiller[618] figured an English specimen of this species, presented to the
impressions of Mosses. The leaf-scars on the smaller shoots occur on
elongated cushions (fig. 212, C, D) with a transversely wrinkled surface; on
the older branches the leaf-scars are separated by fairly large areas of bark
characterised by sinuous transverse grooves and narrow ridges bearing
numerous small pits, as shown on an enlarged scale in fig. 212, A. The
original surface-features are shown on the left of the drawing, and a slightly
deeper level in the cortex is represented on the right-hand side. The absence
of leaf-cushions on the older shoots is probably the result of secondary
thickening, which also alters the size and shape of the leaf-scars. Each scar
has three pits on its surface, as in Lepidodendron; a central leaf-trace scar
and lateral parichnos scars. The circular pit above the leaf-scars, which
occurs in most species, marks the position of the ligule. The relation of the
short leaves, 5 mm. long, to the leaf-cushions is shown in fig. 212, D. The
absence of leaves, except in impressions of slender twigs, may be
interpreted as an indication that they were shed at an early stage and did not
persist many years. The leaf-cushions of the smaller shoots of
Bothrodendron minutifolium closely resemble those figured by Weiss on a
Devonian plant, Lepidodendron Losseni[616].
One of the few examples so far discovered of a Bothrodendron cone is
shown in fig. 213; this specimen, at least 10 cm. long, was found by Mr
Hemingway in the Middle Coal-Measures of Yorkshire and described by Dr
Kidston. Numerous sporophylls are attached at right angles to the axis, the
surface of which is protected by their upturned distal portions; the
arrangement of the parts appears to be the same as in Lepidostrobus. A
specimen figured by Zeiller as Lepidostrobus Olryi, which Kidston is
probably correct in identifying with Bothrodendron minutifolium, shows
that each sporophyll carries a horizontally elongated sporangium (fig. 212,
E).
b. Bothrodendron punctatum Lindley and Hutton[617]. Figs. 211, 212 B, F.
This species, which is less abundant than B. minutifolium, in British
Coal-Measures, has been described by several authors as Ulodendron on
account of the occurrence of large depressions, like those shown in fig. 211,
on certain branches of the plant. At the suggestion of Dr Kidston, Prof.
Zeiller[618] figured an English specimen of this species, presented to the
Page 288
Paris Museum by Mr Hutton, in which the leaf-scars are preserved on the
bark of a stem with Ulodendron scars. The surface of the bark is
characterised by numerous small pits and discontinuous vertical lines in
contrast to the transverse lines of B. minutifolium (cf. fig. 212, A and F).
The leaf-scars on the smaller shoots may have a diameter of only 0·3–0·5
mm., while on the larger branches they reach a breadth of 1 mm. The ligule-
pit may be in contact with the upper edge (fig. 212, F) of the leaf-scar or
separated from it by a short distance.
bark of a stem with Ulodendron scars. The surface of the bark is
characterised by numerous small pits and discontinuous vertical lines in
contrast to the transverse lines of B. minutifolium (cf. fig. 212, A and F).
The leaf-scars on the smaller shoots may have a diameter of only 0·3–0·5
mm., while on the larger branches they reach a breadth of 1 mm. The ligule-
pit may be in contact with the upper edge (fig. 212, F) of the leaf-scar or
separated from it by a short distance.
Page 289
Fig. 213. Bothrodendron minutifolium Cone. From a specimen in Dr Kidston’s Collection.
(Slightly reduced. Kidston (02) Pl. lix.)
c. Bothrodendron kiltorkense (Haughton). Fig. 212, G, H.
(Slightly reduced. Kidston (02) Pl. lix.)
c. Bothrodendron kiltorkense (Haughton). Fig. 212, G, H.
Page 290
1859. Cyclostigma kiltorkense, Haughton, Journ. R. Soc. Dublin,
Vol. ii. p. 418, Pls. xiv.–xvii.
C. minutum, Haughton, Journ. R. Soc. Dublin, Vol. ii. p. 418,
Pls. xiv.–xvii.
C. Griffithsi, Haughton, Journ. R. Soc. Dublin, Vol. ii. p. 418,
Pls. xiv.–xvii.
1870. Lepidodendron Veltheimianum, Heer (ex parte), K. Svensk.
Vet. Akad. Handl. Vol. ix. Pl. ix. figs. 2–4.
Cyclostigma kiltorkense, ibid. Pl. xi. figs. 1–5.
Calamites radiatus (ex parte), ibid. Pl. iii. fig. 2a: Pl. ix. fig.
2b.
Stigmaria ficoides minuta, ibid. Pl. ix. fig. 2c.
Knorria imbricata, ibid. Pl. x. fig. 4.
1889. Bothrodendron kiltorkense, Kidston, Ann. Mag. Nat. Hist.
[vi.], Vol. iv. p. 66.
1894. Bothrodendron kiltorkense, Nathorst, K. Svensk. Vet. Akad.
Handl. Vol. xxvi. No. 4, p. 65, Pls. xiv. xv.
1902. Bothrodendron (Cyclostigma) kiltorkense, ibid. Vol. xxxvi.
No. 3, p. 31, Pls. x.–xiv.
The specimens from the Upper Devonian rocks of Co. Kilkenny on
which Haughton founded this and two other species may be regarded as
representing one specific type. He described the circular leaf-scars as
arranged in alternating whorls. In habit the Irish species agrees with
Bothrodendron minutifolium, but the leaf-scars are more elliptical (fig. 212,
H) and the ligule-pit is usually absent. The leaf-scar shown in fig. H is 1·2
mm. broad and 1·4 mm. in height. The large collection obtained during the
visit of a Swedish expedition to Bear Island in 1898 under the leadership of
Dr Nathorst has materially increased our knowledge of this ancient type.
The form of the leaf-scars varies according to the age of the branch and
their disposition is far from constant even on the same specimen; in some
cases the scars are in fairly regular whorls (fig. 212, G; an Irish specimen)
while in others they are in regular spirals. This irregularity of arrangement,
which is well illustrated by Nathorst’s figures of Bear Island and Irish
specimens, finds its counterpart, though in a less marked form, in recent
species of Lycopodium, e.g. L. Selago. Partially decorticated stems may
present a superficial resemblance to Calamites, the fissured bark simulating
Vol. ii. p. 418, Pls. xiv.–xvii.
C. minutum, Haughton, Journ. R. Soc. Dublin, Vol. ii. p. 418,
Pls. xiv.–xvii.
C. Griffithsi, Haughton, Journ. R. Soc. Dublin, Vol. ii. p. 418,
Pls. xiv.–xvii.
1870. Lepidodendron Veltheimianum, Heer (ex parte), K. Svensk.
Vet. Akad. Handl. Vol. ix. Pl. ix. figs. 2–4.
Cyclostigma kiltorkense, ibid. Pl. xi. figs. 1–5.
Calamites radiatus (ex parte), ibid. Pl. iii. fig. 2a: Pl. ix. fig.
2b.
Stigmaria ficoides minuta, ibid. Pl. ix. fig. 2c.
Knorria imbricata, ibid. Pl. x. fig. 4.
1889. Bothrodendron kiltorkense, Kidston, Ann. Mag. Nat. Hist.
[vi.], Vol. iv. p. 66.
1894. Bothrodendron kiltorkense, Nathorst, K. Svensk. Vet. Akad.
Handl. Vol. xxvi. No. 4, p. 65, Pls. xiv. xv.
1902. Bothrodendron (Cyclostigma) kiltorkense, ibid. Vol. xxxvi.
No. 3, p. 31, Pls. x.–xiv.
The specimens from the Upper Devonian rocks of Co. Kilkenny on
which Haughton founded this and two other species may be regarded as
representing one specific type. He described the circular leaf-scars as
arranged in alternating whorls. In habit the Irish species agrees with
Bothrodendron minutifolium, but the leaf-scars are more elliptical (fig. 212,
H) and the ligule-pit is usually absent. The leaf-scar shown in fig. H is 1·2
mm. broad and 1·4 mm. in height. The large collection obtained during the
visit of a Swedish expedition to Bear Island in 1898 under the leadership of
Dr Nathorst has materially increased our knowledge of this ancient type.
The form of the leaf-scars varies according to the age of the branch and
their disposition is far from constant even on the same specimen; in some
cases the scars are in fairly regular whorls (fig. 212, G; an Irish specimen)
while in others they are in regular spirals. This irregularity of arrangement,
which is well illustrated by Nathorst’s figures of Bear Island and Irish
specimens, finds its counterpart, though in a less marked form, in recent
species of Lycopodium, e.g. L. Selago. Partially decorticated stems may
present a superficial resemblance to Calamites, the fissured bark simulating
Page 291
the ribs of a Calamitean cast. Such stems, as Nathorst has pointed out, were
mistaken by Heer for Calamites radiatus. The smaller branches are
characterised by a smooth surface, and older shoots resemble
Bothrodendron minutifolium in the presence of fine vertical lines. The
preservation of only one pit on the leaf-scars of many examples led authors
to conclude that the species is peculiar in this respect, but Nathorst has
shown that in more perfectly preserved specimens each leaf-scar bears three
small dots. A specimen from Ireland in the British Museum[619] illustrates
the dichotomous branching and the longitudinal wrinkling of the bark; the
leaf-scars are 2 mm. broad and 2·5 mm. deep.
Nathorst[620] has described some examples in which the leaf-scars occur
on the lower instead of on the upper end of the leaf-cushions; these and
other specimens with obscure surface-features he suggests may be
underground axes, comparable in habit with Stigmaria though not identical
as regards details. It is pointed out that the absence or scarcity of Stigmaria
in the Bear Island beds renders it unlikely that Bothrodendron bore typical
Stigmaria branches. F. E. Weiss[621] has recently described root-bearing
organs possessing primary xylem identical with that of Bothrodendron
mundum; while closely resembling Stigmaria ficoides in certain anatomical
characters, they clearly represent a distinct type. This discovery of a
Stigmaria-like axis almost certainly belonging to Bothrodendron is
consistent with Nathorst’s views on some of the Bothrodendron impressions
from Bear Island.
Information as to the cones of this species is restricted to a description by
Schimper[622] of a specimen in the Dublin Museum as Lepidostrobus
Bailyanus; this has sporophylls with a subtriangular base bearing several
megaspores and terminating distally in a slender lamina 12 cm. in length.
An example of a Bothrodendron with more prominent leaf-cushions than
those already mentioned is afforded by a species from Bear Island described
by Heer[623] as Lepidodendron Wükianum and afterwards referred by
Nathorst[624] to Bothrodendron. The same type is recorded also by
Schmalhausen[625] from Lower Carboniferous or Devonian strata of Siberia.
Certain Scotch specimens from the Calciferous Sandstone, which
Kidston[626] referred to Heer’s species, are regarded by Nathorst and, in part
at least, by Weiss[627] and Sterzel as representing a distinct species which
these authors designate Bothrodendron Kidstoni[628].
mistaken by Heer for Calamites radiatus. The smaller branches are
characterised by a smooth surface, and older shoots resemble
Bothrodendron minutifolium in the presence of fine vertical lines. The
preservation of only one pit on the leaf-scars of many examples led authors
to conclude that the species is peculiar in this respect, but Nathorst has
shown that in more perfectly preserved specimens each leaf-scar bears three
small dots. A specimen from Ireland in the British Museum[619] illustrates
the dichotomous branching and the longitudinal wrinkling of the bark; the
leaf-scars are 2 mm. broad and 2·5 mm. deep.
Nathorst[620] has described some examples in which the leaf-scars occur
on the lower instead of on the upper end of the leaf-cushions; these and
other specimens with obscure surface-features he suggests may be
underground axes, comparable in habit with Stigmaria though not identical
as regards details. It is pointed out that the absence or scarcity of Stigmaria
in the Bear Island beds renders it unlikely that Bothrodendron bore typical
Stigmaria branches. F. E. Weiss[621] has recently described root-bearing
organs possessing primary xylem identical with that of Bothrodendron
mundum; while closely resembling Stigmaria ficoides in certain anatomical
characters, they clearly represent a distinct type. This discovery of a
Stigmaria-like axis almost certainly belonging to Bothrodendron is
consistent with Nathorst’s views on some of the Bothrodendron impressions
from Bear Island.
Information as to the cones of this species is restricted to a description by
Schimper[622] of a specimen in the Dublin Museum as Lepidostrobus
Bailyanus; this has sporophylls with a subtriangular base bearing several
megaspores and terminating distally in a slender lamina 12 cm. in length.
An example of a Bothrodendron with more prominent leaf-cushions than
those already mentioned is afforded by a species from Bear Island described
by Heer[623] as Lepidodendron Wükianum and afterwards referred by
Nathorst[624] to Bothrodendron. The same type is recorded also by
Schmalhausen[625] from Lower Carboniferous or Devonian strata of Siberia.
Certain Scotch specimens from the Calciferous Sandstone, which
Kidston[626] referred to Heer’s species, are regarded by Nathorst and, in part
at least, by Weiss[627] and Sterzel as representing a distinct species which
these authors designate Bothrodendron Kidstoni[628].
Page 292
Without attempting the hopeless task of discriminating between the
various Carboniferous and Devonian specimens described under the names
Cyclostigma or Bothrodendron, reference may be made to the following
records as illustrating the wide distribution of the genus. Schmalhausen[629]
records Cyclostigma kiltorkense from Siberian rocks assigned to the Ursa
stage (Devonian or Lower Carboniferous). The fossil described by
Dawson[630] from the Devonian of Gaspé as Cyclostigma densifolium
probably represents a badly preserved example of Bothrodendron: Weiss’s
species Cyclostigma hercynium[631] from Lower Devonian rocks of the Hartz
district may be identical with Bothrodendron kiltorkense. The supposed
identity of the latter species with Dechenia Roemeriana Goepp., as
described by Potonié[632], appears to require confirmation[633], but if this
author is correct the connexion demonstrates the continuity of
Bothrodendron shoots and Stigmaria-like subterranean organs. The
specimens described from South Africa, from strata which may be
correlated with the Upper or possibly with the Lower Carboniferous series
of Europe, as Bothrodendron Leslei[634] in all probability represents a
species closely allied to the Irish and Bear Island type. Bothrodendron
Leslei named after Mr Leslie whose discoveries in the Carboniferous
Sandstone of Vereeniging (Transvaal) have added considerably to our
knowledge of the South African Palaeozoic types, is represented by
imperfectly preserved casts characterised by more or less circular scars
displaying the same irregularity of arrangement as in Bothrodendron
kiltorkense. The leaf-scars appear to have only one small pit, but this may
not be an original feature. The identification of this plant as Bothrodendron
receives support from the discovery of rather more satisfactory specimens
at Witteberg sent to me for examination by Dr Schwarz[635]. These fossils
bear a striking resemblance to B. kiltorkense. Cydostigma australe[636] Feist.
described from the Lower Carboniferous rocks of New South Wales, though
too imperfectly preserved to refer with confidence to B. kiltorkense, is no
doubt a closely allied type.
various Carboniferous and Devonian specimens described under the names
Cyclostigma or Bothrodendron, reference may be made to the following
records as illustrating the wide distribution of the genus. Schmalhausen[629]
records Cyclostigma kiltorkense from Siberian rocks assigned to the Ursa
stage (Devonian or Lower Carboniferous). The fossil described by
Dawson[630] from the Devonian of Gaspé as Cyclostigma densifolium
probably represents a badly preserved example of Bothrodendron: Weiss’s
species Cyclostigma hercynium[631] from Lower Devonian rocks of the Hartz
district may be identical with Bothrodendron kiltorkense. The supposed
identity of the latter species with Dechenia Roemeriana Goepp., as
described by Potonié[632], appears to require confirmation[633], but if this
author is correct the connexion demonstrates the continuity of
Bothrodendron shoots and Stigmaria-like subterranean organs. The
specimens described from South Africa, from strata which may be
correlated with the Upper or possibly with the Lower Carboniferous series
of Europe, as Bothrodendron Leslei[634] in all probability represents a
species closely allied to the Irish and Bear Island type. Bothrodendron
Leslei named after Mr Leslie whose discoveries in the Carboniferous
Sandstone of Vereeniging (Transvaal) have added considerably to our
knowledge of the South African Palaeozoic types, is represented by
imperfectly preserved casts characterised by more or less circular scars
displaying the same irregularity of arrangement as in Bothrodendron
kiltorkense. The leaf-scars appear to have only one small pit, but this may
not be an original feature. The identification of this plant as Bothrodendron
receives support from the discovery of rather more satisfactory specimens
at Witteberg sent to me for examination by Dr Schwarz[635]. These fossils
bear a striking resemblance to B. kiltorkense. Cydostigma australe[636] Feist.
described from the Lower Carboniferous rocks of New South Wales, though
too imperfectly preserved to refer with confidence to B. kiltorkense, is no
doubt a closely allied type.
Page 293
Fig. 214. Bothrodendron Leslei
Seward.
b. Natural size.
a, c. Slightly enlarged.
Seward.
b. Natural size.
a, c. Slightly enlarged.
Page 294
Fig. 215. Bothrodendron mundum (Will.).
A, B. From a specimen (No. 26) in the Cambridge Botany School.
C. British Museum, Williamson Collection. (No. 416 b.)
D, E. From a section in Dr Kidston’s Collection.
Reference was made in Volume I. (p. 133) to the so-called paper coal of
Carboniferous age from Central Russia, which consists of masses of thin
strips of cuticle of Bothrodendron stems. The figures published by
Zeiller[637] show that the plant possessed an epidermis consisting of
polygonal cells interrupted by spirally disposed gaps marking the position
of leaves; the gaps measure 0·5–1·5 mm. in breadth and agree, therefore,
with the size of the leaf-scars of the smaller forms of Bothrodendron. The
specimens from the Russian mines were first figured by Trautschold and
Auerbach[638] as Lepidodendron tenerrimum and afterwards referred by
Zeiller to Bothrodendron punctatum[639]. Nathorst[640], however, states that an
examination of the Russian material leads him to retain the name originally
proposed; he records the same type from Upper Devonian rocks of
Spitzbergen. The chief interest of these Russian specimens is their manner
A, B. From a specimen (No. 26) in the Cambridge Botany School.
C. British Museum, Williamson Collection. (No. 416 b.)
D, E. From a section in Dr Kidston’s Collection.
Reference was made in Volume I. (p. 133) to the so-called paper coal of
Carboniferous age from Central Russia, which consists of masses of thin
strips of cuticle of Bothrodendron stems. The figures published by
Zeiller[637] show that the plant possessed an epidermis consisting of
polygonal cells interrupted by spirally disposed gaps marking the position
of leaves; the gaps measure 0·5–1·5 mm. in breadth and agree, therefore,
with the size of the leaf-scars of the smaller forms of Bothrodendron. The
specimens from the Russian mines were first figured by Trautschold and
Auerbach[638] as Lepidodendron tenerrimum and afterwards referred by
Zeiller to Bothrodendron punctatum[639]. Nathorst[640], however, states that an
examination of the Russian material leads him to retain the name originally
proposed; he records the same type from Upper Devonian rocks of
Spitzbergen. The chief interest of these Russian specimens is their manner
Page 295
of preservation, which Renault has described as the result of bacterial
action; he claims to have recognised the actual bacteria associated with the
cuticular membranes[641].
Anatomy of vegetative shoots of Bothrodendron.
In 1889 Williamson[642] described several specimens of petrified shoots
from the Coal-Measures of Halifax which he named Lepidodendron
mundum: these are now known to be branches of a Bothrodendron. The
discovery was made by Mr Lomax[643] who found specimens showing the
external characters of Bothrodendron and the anatomical characters of
Lepidodendron mundum. In some of the smaller twigs, the stele consists of
a solid core of xylem with external protoxylem; but in the majority of
specimens the centre of the xylem is replaced by parenchymatous tissue,
either as a small axial strand or, as in the specimen shown in fig. 215, D, a
wide pith, the elements of which are arranged in regular vertical series. A
diagrammatic section of a small axis is represented in fig. 215, A: this
branch, 2 mm. in diameter, is composed of a broad outer cortex consisting
exclusively of primary tissue the outer cells of which are smaller and have
thicker walls than the more internal elements. The leaf-traces, lt, are
accompanied by a strand of delicate tissue, the parichnos. The stele is
almost solid; the tissues in contact with the xylem have not been preserved
but the inner cortex is represented by a few layers of small parenchymatous
cells, c1. The larger section shown in fig. 215, D, was cut from a specimen
from Dulesgate of which the smooth surface exhibits the characteristic leaf-
scars of Bothrodendron. The section measures 3 cm. in its longest diameter
and the stele has a breadth of 3 mm. The outer cortex has a smooth surface
and is composed of rather thick-walled cells succeeded by a zone of
secondary elements. The middle cortex has disappeared and the space is
partially occupied by Stigmarian rootlets, s, and crushed patches of cortical
tissue. The position of a leaf-scar is seen at a; this is more clearly shown in
the enlarged drawing fig. E.
In his account of Lepidodendron mundum, Williamson[644] described a
section in which the primary wood is surrounded by a considerable
thickness of secondary xylem; a diagram of this is shown in fig. 215, C. An
examination of the section led me to compare the structure of the outer
cortical cells, characterised by radial rows of tangentially elongated
action; he claims to have recognised the actual bacteria associated with the
cuticular membranes[641].
Anatomy of vegetative shoots of Bothrodendron.
In 1889 Williamson[642] described several specimens of petrified shoots
from the Coal-Measures of Halifax which he named Lepidodendron
mundum: these are now known to be branches of a Bothrodendron. The
discovery was made by Mr Lomax[643] who found specimens showing the
external characters of Bothrodendron and the anatomical characters of
Lepidodendron mundum. In some of the smaller twigs, the stele consists of
a solid core of xylem with external protoxylem; but in the majority of
specimens the centre of the xylem is replaced by parenchymatous tissue,
either as a small axial strand or, as in the specimen shown in fig. 215, D, a
wide pith, the elements of which are arranged in regular vertical series. A
diagrammatic section of a small axis is represented in fig. 215, A: this
branch, 2 mm. in diameter, is composed of a broad outer cortex consisting
exclusively of primary tissue the outer cells of which are smaller and have
thicker walls than the more internal elements. The leaf-traces, lt, are
accompanied by a strand of delicate tissue, the parichnos. The stele is
almost solid; the tissues in contact with the xylem have not been preserved
but the inner cortex is represented by a few layers of small parenchymatous
cells, c1. The larger section shown in fig. 215, D, was cut from a specimen
from Dulesgate of which the smooth surface exhibits the characteristic leaf-
scars of Bothrodendron. The section measures 3 cm. in its longest diameter
and the stele has a breadth of 3 mm. The outer cortex has a smooth surface
and is composed of rather thick-walled cells succeeded by a zone of
secondary elements. The middle cortex has disappeared and the space is
partially occupied by Stigmarian rootlets, s, and crushed patches of cortical
tissue. The position of a leaf-scar is seen at a; this is more clearly shown in
the enlarged drawing fig. E.
In his account of Lepidodendron mundum, Williamson[644] described a
section in which the primary wood is surrounded by a considerable
thickness of secondary xylem; a diagram of this is shown in fig. 215, C. An
examination of the section led me to compare the structure of the outer
cortical cells, characterised by radial rows of tangentially elongated
Page 296
elements, with the outer cortex of Stigmaria. It has recently been shown by
Weiss[645] that this and other similar sections present several points of
agreement with Stigmaria, particularly with Stigmaria Brardi as described
by Renault. At s in fig. 215, C, a vascular strand is seen passing through the
outer cortex; this is almost certainly the bundle of a rootlet: in the sections
described by Weiss rootlets are shown in a similar position. The chief
anatomical features of the Stigmaria-like organs of Bothrodendron are:—
the considerable development of secondary xylem, the structure of the outer
cortex, which is practically identical with that of Stigmaria ficoides, and the
association of groups of short transfusion tracheids with the bundles of the
rootlets. It is very probable that the absence of secondary xylem in the
vegetative shoots of Bothrodendron is merely an accident and not a real
distinction between the aerial and subterranean branches of the plant; a
supposition rendered probable by the occurrence of secondary xylem in the
axis of the cone described by Watson. As Weiss points out, there are certain
differences between the true Stigmaria and the corresponding organ of
Bothrodendron; the secondary xylem in Bothrodendron is not broken up by
broad medullary rays as in the common Stigmaria, and in Bothrodendron
the occurrence of a ring of primary xylem is another peculiarity.
In the vegetative shoots of Bothrodendron mundum the stele differs from
those of Lepidodendron in the narrower primary xylem ring and in the large
size of the metaxylem tracheae; from Lepidodendron Harcourtii and L.
fuliginosum the xylem is distinguished by its smoother outer face which
consists of numerous narrow xylem elements.
Weiss[645] that this and other similar sections present several points of
agreement with Stigmaria, particularly with Stigmaria Brardi as described
by Renault. At s in fig. 215, C, a vascular strand is seen passing through the
outer cortex; this is almost certainly the bundle of a rootlet: in the sections
described by Weiss rootlets are shown in a similar position. The chief
anatomical features of the Stigmaria-like organs of Bothrodendron are:—
the considerable development of secondary xylem, the structure of the outer
cortex, which is practically identical with that of Stigmaria ficoides, and the
association of groups of short transfusion tracheids with the bundles of the
rootlets. It is very probable that the absence of secondary xylem in the
vegetative shoots of Bothrodendron is merely an accident and not a real
distinction between the aerial and subterranean branches of the plant; a
supposition rendered probable by the occurrence of secondary xylem in the
axis of the cone described by Watson. As Weiss points out, there are certain
differences between the true Stigmaria and the corresponding organ of
Bothrodendron; the secondary xylem in Bothrodendron is not broken up by
broad medullary rays as in the common Stigmaria, and in Bothrodendron
the occurrence of a ring of primary xylem is another peculiarity.
In the vegetative shoots of Bothrodendron mundum the stele differs from
those of Lepidodendron in the narrower primary xylem ring and in the large
size of the metaxylem tracheae; from Lepidodendron Harcourtii and L.
fuliginosum the xylem is distinguished by its smoother outer face which
consists of numerous narrow xylem elements.
Page 297
Fig. 216. Bothrostrobus. l, ligule. (After Watson.)
Cones of Bothrodendron (Bothrostrobus[646]).
The long and narrow cones referred to Bothrodendron minutifolium from
English and French Coal-Measures are known only as impressions and it is
not possible to say whether they were heterosporous or homosporous; the
drawing given by Zeiller (Fig. 212, E) shows that the sporangia were of the
same form as those in Lepidostrobus, but we have no more exact
information as to their morphology. A recently published description of a
petrified strobilus by Mr Watson affords a welcome addition to our
knowledge. There is little doubt that this cone was borne by a species of
Bothrodendron; the evidence for this conclusion is supplied by the
agreement of the anatomical characters of the stele with that of the
vegetative shoots originally described by Williamson as Lepidodendron
mundum and by the constant association of the cones and vegetative shoots.
In 1880 Williamson described a crushed cone containing both megaspores
Cones of Bothrodendron (Bothrostrobus[646]).
The long and narrow cones referred to Bothrodendron minutifolium from
English and French Coal-Measures are known only as impressions and it is
not possible to say whether they were heterosporous or homosporous; the
drawing given by Zeiller (Fig. 212, E) shows that the sporangia were of the
same form as those in Lepidostrobus, but we have no more exact
information as to their morphology. A recently published description of a
petrified strobilus by Mr Watson affords a welcome addition to our
knowledge. There is little doubt that this cone was borne by a species of
Bothrodendron; the evidence for this conclusion is supplied by the
agreement of the anatomical characters of the stele with that of the
vegetative shoots originally described by Williamson as Lepidodendron
mundum and by the constant association of the cones and vegetative shoots.
In 1880 Williamson described a crushed cone containing both megaspores
Page 298
and microspores which he spoke of as “a diminutive organism, reminding
us more of the dwarfed fruits of many living Selaginellas than of the large
Lepidostrobi[647].” Watson’s specimens enable us to give a more complete
account of this type. The axis of the strobilus bears short sporophylls bent
upwards into a distal limb with a conspicuous ligule in a deep pit beyond
the shortly stalked sporangium. The length of the strobilus is estimated at
10 mm.; the stele is of the same type as that of Bothrodendron mundum, but
it differs from the specimens of the vegetative shoots so far found in having
some secondary xylem. As shown in the sketch reproduced in fig. 216 each
sporophyll is characterised by two tangentially placed grooves, g, on the
lower face, and by numerous transfusion tracheids, tr, above the vascular
bundle, vb, immediately below the ligule, l. Megasporangia and
microsporangia occur on the same cone, the megasporangia being on the
lower sporophylls and containing a single tetrad of megaspores. Fig. 219, E,
shows a radial longitudinal section of a microsporophyll bearing a
sporangium on the adaxial side of the ligule, l, below which is the single
vascular bundle and a group of short tracheids at t. The sporangia closely
resemble those of species of Selaginella and Lycopodium and, as pointed
out by Watson[648], they also recall the sporangia of the Palaeozoic genus
Spencerites. Bothrostrobus is distinguished from Spencerites by the
presence of a ligule, by the structure of the axis, and by the different form
of the sporophylls. The occurrence of four spores only in the megasporangia
is another character in which the extinct type resembles recent Lycopods. It
is impossible to decide whether Watson’s cone represents a more or a less
primitive type than Lepidostrobus: if we accept Professor Bower’s views in
regard to the evolution of vegetative organs by the sterilisation of
sporogenous tissue, we should probably place Lepidostrobus lower in the
series than Bothrostrobus; but the greater resemblance between the fertile
and vegetative shoots of Bothrodendron, as compared with the more
pronounced difference in the case of Lepidodendron, may be regarded as an
argument in favour of recognising Bothrodendron as the more primitive
type.
Another possible example of a Bothrodendron cone has been described
by Nathorst from Spitzbergen as Lepidostrobus Zeilleri[649]; this appears to
consist of an axis bearing spirally disposed sporangia without any
us more of the dwarfed fruits of many living Selaginellas than of the large
Lepidostrobi[647].” Watson’s specimens enable us to give a more complete
account of this type. The axis of the strobilus bears short sporophylls bent
upwards into a distal limb with a conspicuous ligule in a deep pit beyond
the shortly stalked sporangium. The length of the strobilus is estimated at
10 mm.; the stele is of the same type as that of Bothrodendron mundum, but
it differs from the specimens of the vegetative shoots so far found in having
some secondary xylem. As shown in the sketch reproduced in fig. 216 each
sporophyll is characterised by two tangentially placed grooves, g, on the
lower face, and by numerous transfusion tracheids, tr, above the vascular
bundle, vb, immediately below the ligule, l. Megasporangia and
microsporangia occur on the same cone, the megasporangia being on the
lower sporophylls and containing a single tetrad of megaspores. Fig. 219, E,
shows a radial longitudinal section of a microsporophyll bearing a
sporangium on the adaxial side of the ligule, l, below which is the single
vascular bundle and a group of short tracheids at t. The sporangia closely
resemble those of species of Selaginella and Lycopodium and, as pointed
out by Watson[648], they also recall the sporangia of the Palaeozoic genus
Spencerites. Bothrostrobus is distinguished from Spencerites by the
presence of a ligule, by the structure of the axis, and by the different form
of the sporophylls. The occurrence of four spores only in the megasporangia
is another character in which the extinct type resembles recent Lycopods. It
is impossible to decide whether Watson’s cone represents a more or a less
primitive type than Lepidostrobus: if we accept Professor Bower’s views in
regard to the evolution of vegetative organs by the sterilisation of
sporogenous tissue, we should probably place Lepidostrobus lower in the
series than Bothrostrobus; but the greater resemblance between the fertile
and vegetative shoots of Bothrodendron, as compared with the more
pronounced difference in the case of Lepidodendron, may be regarded as an
argument in favour of recognising Bothrodendron as the more primitive
type.
Another possible example of a Bothrodendron cone has been described
by Nathorst from Spitzbergen as Lepidostrobus Zeilleri[649]; this appears to
consist of an axis bearing spirally disposed sporangia without any
Page 299
indication of sporophylls. This strobilus may belong to Bothrodendron
tenerrimum.
Pinakodendron.
The name Pinakodendron[650] was instituted by the late Prof. Weiss for a
type of stem closely resembling Bothrodendron but differing in the presence
of a fine reticulation on the outer bark and in the form of the leaf-scars.
Weiss’s genus has been recognised by Kidston in Dumfriesshire but our
knowledge of the plant is as yet based solely on a few small specimens.
Omphalophloios (a genus of uncertain systematic position).
Figs. 193, C, 217.
This generic name was instituted by White[651] for certain specimens of
large stems originally described by Lesquereux from the Coal-Measures of
North America as Lepidodendron mammillatum and L. cyclostigma. The
photograph reproduced in fig. 193, C, for which I am indebted to Dr
Kidston[652], represents a specimen described by him from the Upper Coal-
Measures of Somerset as Omphalophloios anglicus, and identified with
Lepidodendron anglicum of Sternberg.
The surface of the impression shown in fig. 193, C, is characterised by
clearly defined rhomboidal areas or cushions (fig. 217, E) like those of
Lepidodendron, except in the absence of a median keel, and similar to those
on some forms of Sigillaria Brardi. A short distance above the centre of
each cushion is an oval or subcordate region bounded by a rim-like margin
and containing a small oval scar, presumably that of a vascular strand. A
triangular elevation which also shows a small pit (Fig. 217, E, a) occurs
below the oval area. The appearance of the surface-features varies
considerably on different parts of a single specimen. Fig. 217, D, represents
one of the numerous figures published by White in his detailed account of
the American material. Each cushion bears a widely open V-shaped ridge,
which is described as a leaf-scar; above this is an oval area (2·5 mm. × 1·75
mm.), the surface of which is bounded by a narrow rim. Within the rim is a
smaller concave oval region with a small pit near its upper end.
tenerrimum.
Pinakodendron.
The name Pinakodendron[650] was instituted by the late Prof. Weiss for a
type of stem closely resembling Bothrodendron but differing in the presence
of a fine reticulation on the outer bark and in the form of the leaf-scars.
Weiss’s genus has been recognised by Kidston in Dumfriesshire but our
knowledge of the plant is as yet based solely on a few small specimens.
Omphalophloios (a genus of uncertain systematic position).
Figs. 193, C, 217.
This generic name was instituted by White[651] for certain specimens of
large stems originally described by Lesquereux from the Coal-Measures of
North America as Lepidodendron mammillatum and L. cyclostigma. The
photograph reproduced in fig. 193, C, for which I am indebted to Dr
Kidston[652], represents a specimen described by him from the Upper Coal-
Measures of Somerset as Omphalophloios anglicus, and identified with
Lepidodendron anglicum of Sternberg.
The surface of the impression shown in fig. 193, C, is characterised by
clearly defined rhomboidal areas or cushions (fig. 217, E) like those of
Lepidodendron, except in the absence of a median keel, and similar to those
on some forms of Sigillaria Brardi. A short distance above the centre of
each cushion is an oval or subcordate region bounded by a rim-like margin
and containing a small oval scar, presumably that of a vascular strand. A
triangular elevation which also shows a small pit (Fig. 217, E, a) occurs
below the oval area. The appearance of the surface-features varies
considerably on different parts of a single specimen. Fig. 217, D, represents
one of the numerous figures published by White in his detailed account of
the American material. Each cushion bears a widely open V-shaped ridge,
which is described as a leaf-scar; above this is an oval area (2·5 mm. × 1·75
mm.), the surface of which is bounded by a narrow rim. Within the rim is a
smaller concave oval region with a small pit near its upper end.
Page 300
Fig. 217.
Omphalophloios. D. After White. E. After Kidston.
We cannot, in the absence of petrified material, arrive at any satisfactory
conclusion as to the meaning of these surface-features. White considers that
Omphalophloios is probably a rhizome of one of the arborescent Lycopods,
but whether or not this is its true nature must be left for future discoveries.
The fact that the rootlet bundles of some Stigmarian axes are accompanied
by a parichnos strand, as Weiss has shown, may prepare us for the discovery
of surface-features on Stigmariae not unlike those of Omphalophloios. (Fig.
193, C.)
A possible comparison may be suggested also with Sigillaria Brardi as
figured by Germar (fig. 196, A) in which circular scars, which may be the
scars of rootlets, occur below the leaf-base areas. It is not impossible that in
the surface-features of Omphalophloios we have both leaf and rootlet scars
represented.
General considerations.
The solid xylem core characteristic of the stele of some species of
Palaeozoic Lycopodiales (e.g. Lepidodendron esnostense and L.
rhodumnense) may probably, as Tansley and Chick[653] point out, be
regarded as the lineal descendant of a primitive axial strand of water-
conducting elements. In the course of evolution the centre of the tracheal
column became partially converted into parenchymatous tissue, as in
Lepidodendron vasculare. The arrangement of the short cells in regular
vertical series is reminiscent of an early stage in the development of
tracheae: instead of forming tubular conducting elements the central part of
the stelar meristem acquired the short-celled form; some of the cells became
lignified as isodiametric storage tracheae while others persisted as thin-
walled parenchyma.
Omphalophloios. D. After White. E. After Kidston.
We cannot, in the absence of petrified material, arrive at any satisfactory
conclusion as to the meaning of these surface-features. White considers that
Omphalophloios is probably a rhizome of one of the arborescent Lycopods,
but whether or not this is its true nature must be left for future discoveries.
The fact that the rootlet bundles of some Stigmarian axes are accompanied
by a parichnos strand, as Weiss has shown, may prepare us for the discovery
of surface-features on Stigmariae not unlike those of Omphalophloios. (Fig.
193, C.)
A possible comparison may be suggested also with Sigillaria Brardi as
figured by Germar (fig. 196, A) in which circular scars, which may be the
scars of rootlets, occur below the leaf-base areas. It is not impossible that in
the surface-features of Omphalophloios we have both leaf and rootlet scars
represented.
General considerations.
The solid xylem core characteristic of the stele of some species of
Palaeozoic Lycopodiales (e.g. Lepidodendron esnostense and L.
rhodumnense) may probably, as Tansley and Chick[653] point out, be
regarded as the lineal descendant of a primitive axial strand of water-
conducting elements. In the course of evolution the centre of the tracheal
column became partially converted into parenchymatous tissue, as in
Lepidodendron vasculare. The arrangement of the short cells in regular
vertical series is reminiscent of an early stage in the development of
tracheae: instead of forming tubular conducting elements the central part of
the stelar meristem acquired the short-celled form; some of the cells became
lignified as isodiametric storage tracheae while others persisted as thin-
walled parenchyma.
Page 301
The production of secondary xylem and an increase in the girth of the
whole stem led to reduction in the amount of centripetally developed
conducting channels. Some of these assumed a new rôle and a shape in
harmony with their functions. A later stage is represented by a further
encroachment of the central parenchyma on the cylinder of centripetal
xylem, as seen in Lepidodendron Harcourtii and other species. The next
stage is afforded by ribless species of Sigillaria in which the primary xylem
is broken up into separate conducting strands. As Kidston[654] reminds us, it
is in the geologically more recent species of Sigillaria, such as S. Brardi,
which persist into the Permian era, that this more extreme case of reduction
occurs. The older genus Lepidodendron seems to have retained to the last
the complete cylinder of primary xylem. In the stele of Stigmaria, the
rhizome of Sigillaria and of Lepidodendron, reduction of the centripetal
xylem has passed beyond the stage represented by the broken cylinder of
the ribless Sigillarias. With the exception of the examples described by
Renault[655] and by Weiss[656], Stigmaria is characterised by little or no
centripetal primary xylem. It is, however, noteworthy that Renault’s
Stigmaria, in which centripetal xylem forms a prominent feature, is
attributed to Sigillaria Brardi, a species in which the vascular cylinder of
the aerial stem illustrates a later and not an earlier phase in the replacement
of centripetal by centrifugal wood.
It would seem, as Lady Isabel Browne[657] says, that most Stigmarian axes
had reached a more advanced stage in specialisation than is shown in the
stelar structure of the aerial shoots. The relatively greater and probably the
more precocious development of secondary xylem in Stigmaria than in
Lepidodendron or Sigillaria may have some significance in relation to the
smaller amount of “old wood[658]” (in a phylogenetic sense) in their steles.
As is pointed out in a later chapter, recent researches into the anatomy of
extinct members of the Osmundaceae by Kidston and Gwynne-Vaughan
have brought to light a striking parallelism in evolutionary sequence
between the Lepidodendreae and the ancestors of Osmunda and Todea, the
two surviving genera of one of the most ancient families of ferns.
There can be little doubt as to a very close relationship between
Sigillaria, Lepidodendron, and Bothrodendron. Sigillaria seems to have
outlived Lepidodendron and Bothrodendron. The two latter genera are
recorded from Upper Devonian rocks in several localities, Bothrodendron
whole stem led to reduction in the amount of centripetally developed
conducting channels. Some of these assumed a new rôle and a shape in
harmony with their functions. A later stage is represented by a further
encroachment of the central parenchyma on the cylinder of centripetal
xylem, as seen in Lepidodendron Harcourtii and other species. The next
stage is afforded by ribless species of Sigillaria in which the primary xylem
is broken up into separate conducting strands. As Kidston[654] reminds us, it
is in the geologically more recent species of Sigillaria, such as S. Brardi,
which persist into the Permian era, that this more extreme case of reduction
occurs. The older genus Lepidodendron seems to have retained to the last
the complete cylinder of primary xylem. In the stele of Stigmaria, the
rhizome of Sigillaria and of Lepidodendron, reduction of the centripetal
xylem has passed beyond the stage represented by the broken cylinder of
the ribless Sigillarias. With the exception of the examples described by
Renault[655] and by Weiss[656], Stigmaria is characterised by little or no
centripetal primary xylem. It is, however, noteworthy that Renault’s
Stigmaria, in which centripetal xylem forms a prominent feature, is
attributed to Sigillaria Brardi, a species in which the vascular cylinder of
the aerial stem illustrates a later and not an earlier phase in the replacement
of centripetal by centrifugal wood.
It would seem, as Lady Isabel Browne[657] says, that most Stigmarian axes
had reached a more advanced stage in specialisation than is shown in the
stelar structure of the aerial shoots. The relatively greater and probably the
more precocious development of secondary xylem in Stigmaria than in
Lepidodendron or Sigillaria may have some significance in relation to the
smaller amount of “old wood[658]” (in a phylogenetic sense) in their steles.
As is pointed out in a later chapter, recent researches into the anatomy of
extinct members of the Osmundaceae by Kidston and Gwynne-Vaughan
have brought to light a striking parallelism in evolutionary sequence
between the Lepidodendreae and the ancestors of Osmunda and Todea, the
two surviving genera of one of the most ancient families of ferns.
There can be little doubt as to a very close relationship between
Sigillaria, Lepidodendron, and Bothrodendron. Sigillaria seems to have
outlived Lepidodendron and Bothrodendron. The two latter genera are
recorded from Upper Devonian rocks in several localities, Bothrodendron
Page 302
being particularly abundant in the pre-Carboniferous floras of Bear Island
and other parts of the world. A remarkable stem described by Dr White[659]
as Archaeosigillaria primaeva from Upper Devonian shales of New York is
spoken of by him as “one of the most highly developed representatives of a
fairly distinct archaic group foreshadowing the later genera Bothrodendron,
Sigillaria, Lepidodendron and Lepidophloios.” The type-specimen, when
first discovered, consisted of an apparently unbranched stem reaching a
length of 5 metres. From the swollen basal part Stigmaria-like rootlets
spread into the surrounding shale. At a higher level the fissured bark shows
indistinctly defined leaf-cushions which pass gradually upwards into
cushions and scars arranged in closer order on regular vertical ribs. The
surface-features in this region are practically those of a ribbed Sigillaria.
Traced farther upwards the vertical ribs die out and cushions of the
Lepidodendroid form cover the surface of the bark. The leaf-scars, with a
supraposed ligular pit and two vertically elongated parichnos-scars, are said
to bear a closer resemblance to those of Sigillaria and Bothrodendron than
to the leaf-areas of Lepidodendron. Nothing is known as to the anatomy of
this stem, nor have fertile shoots been discovered. In the absence of more
trustworthy evidence than is available conclusions of a phylogenetic nature
must be accepted at their true value. It is however legitimate to describe
Archaeosigillaria primaeva as one of the oldest examples of a
lycopodiaceous plant which shows well-preserved external features, and
these are of exceptional interest as indicating a combination of generic
characters. This Devonian type lends support to the view that
Lepidodendron and Sigillaria are offshoots, differing from one another in
comparatively unimportant points, from a common ancestral type.
The generally accepted statement that arborescent Palaeozoic
Lycopodiales bore their sporangia on specially modified leaves
(sporophylls) grouped in cones which were usually produced at the tip of
slender branches, has recently shared the fate of most rules. Prof. Bower in
his Origin of a Land Flora mentions a Belgian specimen of Pinakodendron
musivum Weiss from the Westphalian series (Middle Coal-Measures), to be
described by Dr Kidston, which bore its sporangia “associated with the
leaves of certain portions of the stem, without any cone-formation. The
fertile and sterile portions are distinguished only by the presence or absence
of sporangia[660].”
and other parts of the world. A remarkable stem described by Dr White[659]
as Archaeosigillaria primaeva from Upper Devonian shales of New York is
spoken of by him as “one of the most highly developed representatives of a
fairly distinct archaic group foreshadowing the later genera Bothrodendron,
Sigillaria, Lepidodendron and Lepidophloios.” The type-specimen, when
first discovered, consisted of an apparently unbranched stem reaching a
length of 5 metres. From the swollen basal part Stigmaria-like rootlets
spread into the surrounding shale. At a higher level the fissured bark shows
indistinctly defined leaf-cushions which pass gradually upwards into
cushions and scars arranged in closer order on regular vertical ribs. The
surface-features in this region are practically those of a ribbed Sigillaria.
Traced farther upwards the vertical ribs die out and cushions of the
Lepidodendroid form cover the surface of the bark. The leaf-scars, with a
supraposed ligular pit and two vertically elongated parichnos-scars, are said
to bear a closer resemblance to those of Sigillaria and Bothrodendron than
to the leaf-areas of Lepidodendron. Nothing is known as to the anatomy of
this stem, nor have fertile shoots been discovered. In the absence of more
trustworthy evidence than is available conclusions of a phylogenetic nature
must be accepted at their true value. It is however legitimate to describe
Archaeosigillaria primaeva as one of the oldest examples of a
lycopodiaceous plant which shows well-preserved external features, and
these are of exceptional interest as indicating a combination of generic
characters. This Devonian type lends support to the view that
Lepidodendron and Sigillaria are offshoots, differing from one another in
comparatively unimportant points, from a common ancestral type.
The generally accepted statement that arborescent Palaeozoic
Lycopodiales bore their sporangia on specially modified leaves
(sporophylls) grouped in cones which were usually produced at the tip of
slender branches, has recently shared the fate of most rules. Prof. Bower in
his Origin of a Land Flora mentions a Belgian specimen of Pinakodendron
musivum Weiss from the Westphalian series (Middle Coal-Measures), to be
described by Dr Kidston, which bore its sporangia “associated with the
leaves of certain portions of the stem, without any cone-formation. The
fertile and sterile portions are distinguished only by the presence or absence
of sporangia[660].”
Page 303
Lepidodendron and Sigillaria can hardly be claimed as the direct
ancestors of any existing type of Lycopodiales, but while exhibiting points
of contact with Lycopodium, Selaginella, and Psilotum they are perhaps
more closely allied to Isoetes.
Lady Isabel Browne[661], who has recently published an excellent
summary of the evidence on the relation of the Lepidodendreae to Isoetes,
concludes her examination of the arguments by expressing the opinion that
there is a strong probability of the correctness of the view that Isoetes may
be derived “from the Lepidodendraceae in the widest sense of the word.”
This decision seems to me to accord best with the facts.
The further question as to the relation of these Palaeozoic genera to
plants higher in the scale must be reserved for fuller consideration in
another volume. An attempt will also be made to consider how far
anatomical structure may be used as a guide to the conditions under which
Lepidodendron and Sigillaria as well as other members of the Permo-
Carboniferous floras passed their lives. The secondary xylem of
Lepidodendron and Sigillaria affords a striking example of water-
conducting tissue of homogeneous structure comparable with the wood of
Conifers rather than with that of Angiosperms. It was presumably formed,
for the most part, under uniform climatic conditions: the absence of rings of
growth points to uninterrupted supply to evergreen shoots exposed to no
alternation of activity and arrested growth. Attention has already been
called to the absence of any tissue corresponding to secondary phloem.
Even in young shoots of Lepidodendron, no tissue has been found external
to the meristematic zone agreeing in the form of its elements with the
channels through which the elaborated food is conveyed from the leaves of
recent plants to the regions of cell-building. That the ‘secretory zone’ may
have served this purpose, at least in young stems, is not improbable. On the
other hand, it is difficult to understand why older Lepidodendron stems
show no indication of additions to the secretory zone. If this tissue served
for the transport of proteids we should expect to find provision made for its
constant renewal pari passu with the secondary growth of the xylem. The
conclusion seems to me inevitable that the supply of building-material was
otherwise provided for than in recent vascular plants. The physiological
division of labour may have been less complete in the tissue-systems of the
Palaeozoic Lycopods than in the more highly specialised organs of such an
ancestors of any existing type of Lycopodiales, but while exhibiting points
of contact with Lycopodium, Selaginella, and Psilotum they are perhaps
more closely allied to Isoetes.
Lady Isabel Browne[661], who has recently published an excellent
summary of the evidence on the relation of the Lepidodendreae to Isoetes,
concludes her examination of the arguments by expressing the opinion that
there is a strong probability of the correctness of the view that Isoetes may
be derived “from the Lepidodendraceae in the widest sense of the word.”
This decision seems to me to accord best with the facts.
The further question as to the relation of these Palaeozoic genera to
plants higher in the scale must be reserved for fuller consideration in
another volume. An attempt will also be made to consider how far
anatomical structure may be used as a guide to the conditions under which
Lepidodendron and Sigillaria as well as other members of the Permo-
Carboniferous floras passed their lives. The secondary xylem of
Lepidodendron and Sigillaria affords a striking example of water-
conducting tissue of homogeneous structure comparable with the wood of
Conifers rather than with that of Angiosperms. It was presumably formed,
for the most part, under uniform climatic conditions: the absence of rings of
growth points to uninterrupted supply to evergreen shoots exposed to no
alternation of activity and arrested growth. Attention has already been
called to the absence of any tissue corresponding to secondary phloem.
Even in young shoots of Lepidodendron, no tissue has been found external
to the meristematic zone agreeing in the form of its elements with the
channels through which the elaborated food is conveyed from the leaves of
recent plants to the regions of cell-building. That the ‘secretory zone’ may
have served this purpose, at least in young stems, is not improbable. On the
other hand, it is difficult to understand why older Lepidodendron stems
show no indication of additions to the secretory zone. If this tissue served
for the transport of proteids we should expect to find provision made for its
constant renewal pari passu with the secondary growth of the xylem. The
conclusion seems to me inevitable that the supply of building-material was
otherwise provided for than in recent vascular plants. The physiological
division of labour may have been less complete in the tissue-systems of the
Palaeozoic Lycopods than in the more highly specialised organs of such an
Page 304
extinct genus as Lyginodendron or than in recent plants. Our knowledge of
the anatomical structure of many extinct types has already reached a stage
when we should take greater heed of the modus operandi of the complex
machinery revealed by a study of petrified stems. From the known we
proceed to interpret the unknown; but there is a danger of neglecting the
possibilities of evolution during the countless ages which separate the
forests of the Coal period from those of the present era. We may easily
allow preconceived ideas to warp our judgment in attempting to distribute
the manifold activities which made up the life of a Lepidodendron among
the structural units of the plant-body.
the anatomical structure of many extinct types has already reached a stage
when we should take greater heed of the modus operandi of the complex
machinery revealed by a study of petrified stems. From the known we
proceed to interpret the unknown; but there is a danger of neglecting the
possibilities of evolution during the countless ages which separate the
forests of the Coal period from those of the present era. We may easily
allow preconceived ideas to warp our judgment in attempting to distribute
the manifold activities which made up the life of a Lepidodendron among
the structural units of the plant-body.
Page 305
Page 306
CHAPTER XIX.
Seed-bearing plants closely allied to members of the Lycopodiales.
i. Lepidocarpon.
In 1877 Williamson[662] published an account of some fossil seeds which
he referred to Brongniart’s genus Cardiocarpon[663], a generic title for
certain Gymnospermous seeds. Some of these he identified, on the authority
of the author of the species, with Cardiocarpon anomalum Carruthers[664].
Several years later Wild and Lomax described a new type of strobilus from
the Lower Coal-Measures of Lancashire[665]. The result of this discovery and
of the subsequent examination by Scott of additional material, was to
establish the fact that the seeds described by Williamson and generally
accepted as Gymnospermous, are in reality sporangia belonging to a
Lycopodiaceous cone. The seeds to which Carruthers gave the name
Cardiocarpon anomalum are, however, distinct from those described under
the same name by Williamson and are those of a true Gymnosperm. For this
seed-bearing strobilus Scott[666] instituted the generic name Lepidocarpon,
which he thus defined: “Strobili, with the characters of Lepidostrobus, but
each megasporangium was inclosed, when mature, in an integument,
growing up from the superior face of the sporophyll-pedicel. Integument,
together with the lamina of the sporophyll, completely enveloping the
megasporangium, or nucellus, leaving only an elongated, slit-like micropyle
above. A single functional megaspore or embryo-sac developed in each
megasporangium, occupying almost the whole of its cavity. Megaspore
ultimately filled by the prothallus or endosperm. Sporophyll, together with
the integumented megasporangium and its contents, detached entire from
the axis of the strobilus, the whole forming a closed, seed-like, reproductive
body. Seed-like organ horizontally elongated, in the direction of the
sporophyll-pedicel, to which the micropylar crevice is parallel.”
Lepidocarpon Lomaxi, Scott. Fig. 218.
Seed-bearing plants closely allied to members of the Lycopodiales.
i. Lepidocarpon.
In 1877 Williamson[662] published an account of some fossil seeds which
he referred to Brongniart’s genus Cardiocarpon[663], a generic title for
certain Gymnospermous seeds. Some of these he identified, on the authority
of the author of the species, with Cardiocarpon anomalum Carruthers[664].
Several years later Wild and Lomax described a new type of strobilus from
the Lower Coal-Measures of Lancashire[665]. The result of this discovery and
of the subsequent examination by Scott of additional material, was to
establish the fact that the seeds described by Williamson and generally
accepted as Gymnospermous, are in reality sporangia belonging to a
Lycopodiaceous cone. The seeds to which Carruthers gave the name
Cardiocarpon anomalum are, however, distinct from those described under
the same name by Williamson and are those of a true Gymnosperm. For this
seed-bearing strobilus Scott[666] instituted the generic name Lepidocarpon,
which he thus defined: “Strobili, with the characters of Lepidostrobus, but
each megasporangium was inclosed, when mature, in an integument,
growing up from the superior face of the sporophyll-pedicel. Integument,
together with the lamina of the sporophyll, completely enveloping the
megasporangium, or nucellus, leaving only an elongated, slit-like micropyle
above. A single functional megaspore or embryo-sac developed in each
megasporangium, occupying almost the whole of its cavity. Megaspore
ultimately filled by the prothallus or endosperm. Sporophyll, together with
the integumented megasporangium and its contents, detached entire from
the axis of the strobilus, the whole forming a closed, seed-like, reproductive
body. Seed-like organ horizontally elongated, in the direction of the
sporophyll-pedicel, to which the micropylar crevice is parallel.”
Lepidocarpon Lomaxi, Scott. Fig. 218.
Page 307
An immature cone of L. Lomaxi is practically identical with a
Lepidostrobus; its sporangia are naked and only acquire their integuments at
a later stage. A mature strobilus has a diameter of at least 3 cm. and is about
4 cm. in length. As in typical Lepidostrobi, the axis bears spirally disposed
sporophylls, and each sporophyll has a long narrow pedicel approximately
at right angles to the cone axis with its distal end expanded into a broad and
thick lamina (fig. 218, B).
At the distal end the pedicel has a thin marginal wing (fig. 218, C, right-
hand half) continuous with the upturned protective lamina. To the upper
face of each sporophyll is attached along the whole length as far as the
ligule, a single large sporangium; on each side of the base of the
sporangium the sporophyll forms a supporting cushion. The relation of the
sporangium to the ligule, l, is shown in fig. 218, B, and in the tangential
section, C, which illustrates the triangular form of the sporangium near its
distal end.
In mature cones, the sporangia assumed the form of seeds, the change
being due to the growth of an investing integument from the upper face of
the sporophylls on each side of the sporangia. Fig. 218, A, illustrates the
form of a sporangium as shown in tangential sections; the vascular bundle
is seen below the base of the sporangium and the gaps right and left of it
probably mark the position of parichnos strands. On each side of the
sporangium, b, a fairly thick wall of tissue has grown up from the
sporophyll, forming an integument which overtops the apical ridge of the
sporangium, leaving a narrow micropyle in the form of a long crevice (m,
fig. 218, B). At the proximal end of the sporangium the integument forms
an enclosing wall; at the distal end it abuts on and is continuous with the
upturned end of the sporophyll. It is clearly established by Scott that the
tissue which invests the sporangia is not the upturned margins of the
sporophyll, but a new formation fully entitled to the designation
integument. It is noteworthy that the integument is not developed until a
late stage in the ontogeny of the strobilus; it is not formed until after the
production of the prothallus[667]. The diagrammatic sketch, fig. 218, B,
shows the relation of the integument to the sporophyll and sporangium, the
outline of the latter being indicated by a broken line. The columnar wall of
the sporangium (fig. 218, A, b) forms a closed beak within the micropylar
crevice, and in the interior of the sporangial cavity the slightly shrivelled
Lepidostrobus; its sporangia are naked and only acquire their integuments at
a later stage. A mature strobilus has a diameter of at least 3 cm. and is about
4 cm. in length. As in typical Lepidostrobi, the axis bears spirally disposed
sporophylls, and each sporophyll has a long narrow pedicel approximately
at right angles to the cone axis with its distal end expanded into a broad and
thick lamina (fig. 218, B).
At the distal end the pedicel has a thin marginal wing (fig. 218, C, right-
hand half) continuous with the upturned protective lamina. To the upper
face of each sporophyll is attached along the whole length as far as the
ligule, a single large sporangium; on each side of the base of the
sporangium the sporophyll forms a supporting cushion. The relation of the
sporangium to the ligule, l, is shown in fig. 218, B, and in the tangential
section, C, which illustrates the triangular form of the sporangium near its
distal end.
In mature cones, the sporangia assumed the form of seeds, the change
being due to the growth of an investing integument from the upper face of
the sporophylls on each side of the sporangia. Fig. 218, A, illustrates the
form of a sporangium as shown in tangential sections; the vascular bundle
is seen below the base of the sporangium and the gaps right and left of it
probably mark the position of parichnos strands. On each side of the
sporangium, b, a fairly thick wall of tissue has grown up from the
sporophyll, forming an integument which overtops the apical ridge of the
sporangium, leaving a narrow micropyle in the form of a long crevice (m,
fig. 218, B). At the proximal end of the sporangium the integument forms
an enclosing wall; at the distal end it abuts on and is continuous with the
upturned end of the sporophyll. It is clearly established by Scott that the
tissue which invests the sporangia is not the upturned margins of the
sporophyll, but a new formation fully entitled to the designation
integument. It is noteworthy that the integument is not developed until a
late stage in the ontogeny of the strobilus; it is not formed until after the
production of the prothallus[667]. The diagrammatic sketch, fig. 218, B,
shows the relation of the integument to the sporophyll and sporangium, the
outline of the latter being indicated by a broken line. The columnar wall of
the sporangium (fig. 218, A, b) forms a closed beak within the micropylar
crevice, and in the interior of the sporangial cavity the slightly shrivelled
Page 308
membrane, a, represents the single megaspore; traces of the aborted sister-
cells of the megaspore are occasionally met with. Scott describes a
specimen in which the megaspore is filled with tissue agreeing in
appearance with the prothallus in a megaspore of Isoetes or Selaginella; no
undoubted archegonia or female organs have been discovered, nor has any
spore been found containing an embryo.
Fig. 218. Lepidocarpon Lomaxi, Scott.
A and C. After Scott.
B. Diagram of a single sporophyll: m, micropyle; St, stele.
cells of the megaspore are occasionally met with. Scott describes a
specimen in which the megaspore is filled with tissue agreeing in
appearance with the prothallus in a megaspore of Isoetes or Selaginella; no
undoubted archegonia or female organs have been discovered, nor has any
spore been found containing an embryo.
Fig. 218. Lepidocarpon Lomaxi, Scott.
A and C. After Scott.
B. Diagram of a single sporophyll: m, micropyle; St, stele.
Page 309
The axis of L. Lomaxi has a medullated stele constructed on the same
plan as that of some species of Lepidodendron and Lepidostrobus; the
vascular bundles supplying the sporophylls pass obliquely upwards and
outwards from the stele, St, fig. 218, B, and bend slightly downward just
before entering the pedicel of a sporophyll.
Dr Scott has also described a strobilus containing microsporangia
partially enclosed by a rudimentary integument. It is, however, of
considerable interest to find a partial development in the case of a male
flower of an integumentary outgrowth, which it would seem could only be
of real functional importance in the female shoot.
It is important to notice that specimens of a second species of
Lepidocarpon, L. Wildianum, are recorded from Lower Carboniferous beds
of Scotland, a fact which points to a considerable antiquity for this seed-
bearing Lycopodiaceous type[668].
The most important question to consider in regard to Lepidocarpon is—
are we justified in applying to the integumented sporangia the term seed?
The megaspore was not set free as it is in recent Pteridophytes, such as
Azolla and other genera with which Lepidocarpon may be compared; it was
on the other hand retained in the sporangium, as may sometimes happen
even in recent species of Selaginella (cf. fig. 131, D). Moreover, the
megaspore is characterised by a thin enclosing membrane in contrast to the
thick coat of a spore which is destined to be shed. The peculiar slit-like
form of the micropyle is a distinguishing feature, but this may be readily
explained as a convenient form in the case of a radially elongated
sporangium. The absence of an embryo, though a distinguishing feature of
Lepidocarpon, cannot be held to be a serious obstacle to the use of the term
seed; in recent Cycads the embryo, as Scott points out, may not begin to
develope until the seed has been shed. It is possible that the seeds of
Lepidocarpon were not pollinated on the parent plant.
The lesson which this extinct type teaches, is that certain Lycopodiaceous
plants of the Palaeozoic era had reached an important stage in the evolution
of a seed. The morphological essentials of true seeds had been acquired; but
we do not know the biological conditions under which pollination and
fertilisation were effected. Another point of considerable interest is the
value of this discovery as an argument in favour of the view that some
plan as that of some species of Lepidodendron and Lepidostrobus; the
vascular bundles supplying the sporophylls pass obliquely upwards and
outwards from the stele, St, fig. 218, B, and bend slightly downward just
before entering the pedicel of a sporophyll.
Dr Scott has also described a strobilus containing microsporangia
partially enclosed by a rudimentary integument. It is, however, of
considerable interest to find a partial development in the case of a male
flower of an integumentary outgrowth, which it would seem could only be
of real functional importance in the female shoot.
It is important to notice that specimens of a second species of
Lepidocarpon, L. Wildianum, are recorded from Lower Carboniferous beds
of Scotland, a fact which points to a considerable antiquity for this seed-
bearing Lycopodiaceous type[668].
The most important question to consider in regard to Lepidocarpon is—
are we justified in applying to the integumented sporangia the term seed?
The megaspore was not set free as it is in recent Pteridophytes, such as
Azolla and other genera with which Lepidocarpon may be compared; it was
on the other hand retained in the sporangium, as may sometimes happen
even in recent species of Selaginella (cf. fig. 131, D). Moreover, the
megaspore is characterised by a thin enclosing membrane in contrast to the
thick coat of a spore which is destined to be shed. The peculiar slit-like
form of the micropyle is a distinguishing feature, but this may be readily
explained as a convenient form in the case of a radially elongated
sporangium. The absence of an embryo, though a distinguishing feature of
Lepidocarpon, cannot be held to be a serious obstacle to the use of the term
seed; in recent Cycads the embryo, as Scott points out, may not begin to
develope until the seed has been shed. It is possible that the seeds of
Lepidocarpon were not pollinated on the parent plant.
The lesson which this extinct type teaches, is that certain Lycopodiaceous
plants of the Palaeozoic era had reached an important stage in the evolution
of a seed. The morphological essentials of true seeds had been acquired; but
we do not know the biological conditions under which pollination and
fertilisation were effected. Another point of considerable interest is the
value of this discovery as an argument in favour of the view that some
Page 310
Gymnosperms are derived from Lycopod ancestors. Leaving the general
question until later, it may at any rate be stated that in Lepidocarpon we
have a demonstration of the fact that the Lycopodiales were not always
distinguished from Gymnosperms by the absence of seeds. There are certain
features in Lepidocarpon shared by the seeds of Araucarieae[669] which may
well mean something more than mere parallel development in two distinct
phyla of the plant-kingdom[670].
ii. Miadesmia.
In 1894 Prof. Bertrand[671] published an account of certain fragments of
petrified leaves and twigs of a small herbaceous Lycopodiaceous plant,
under the name Miadesmia membranacea, which he discovered in English
material in association with Lepidodendron Harcourtii. Subsequently Scott
recognised the megasporophylls of the same plant, and microsporophylls
have also been discovered. The most complete account of Miadesmia so far
published we owe to Dr Benson[672], whose description is based on
specimens from several sources.
Miadesmia membranacea, Bertrand. Fig. 219, A–D.
question until later, it may at any rate be stated that in Lepidocarpon we
have a demonstration of the fact that the Lycopodiales were not always
distinguished from Gymnosperms by the absence of seeds. There are certain
features in Lepidocarpon shared by the seeds of Araucarieae[669] which may
well mean something more than mere parallel development in two distinct
phyla of the plant-kingdom[670].
ii. Miadesmia.
In 1894 Prof. Bertrand[671] published an account of certain fragments of
petrified leaves and twigs of a small herbaceous Lycopodiaceous plant,
under the name Miadesmia membranacea, which he discovered in English
material in association with Lepidodendron Harcourtii. Subsequently Scott
recognised the megasporophylls of the same plant, and microsporophylls
have also been discovered. The most complete account of Miadesmia so far
published we owe to Dr Benson[672], whose description is based on
specimens from several sources.
Miadesmia membranacea, Bertrand. Fig. 219, A–D.
Page 311
Fig. 219.
A–D Miadesmia; E Bothrodendron.
A. Radial section of megasporophyll: s, sporangium; m, megaspore; l, ligule. (From a
drawing kindly lent by Mrs D. H. Scott.)
B, C. Leaf with ligule. (From a section in Dr Kidston’s Collection.)
D. Transverse section of sporophyll. (After Scott.)
E. Radial section of microsporophyll of Bothrodendron. (From a section in the Manchester
Museum; Hick Collection R. 406.)
The slender stem, characterised by unequal dichotomy, has a single
protostele composed of scalariform tracheids with 3–6 peripheral
protoxylem groups. A zone of delicate tissue surrounds the xylem; this is
described as phloem, but it is not clear whether the designation is based on
histological characters or primarily on its position. The cortex consists of an
inner lacunar tissue and an outer region limited by a small-celled superficial
layer sharply contrasted with the underlying layers of larger cells. The stem
of Miadesmia is not uncommon in sections of the Lancashire calcareous
nodules, and may be recognised by the delicate crushed tissue of which it
mainly consists and by large hypodermal parenchyma. The spirally
A–D Miadesmia; E Bothrodendron.
A. Radial section of megasporophyll: s, sporangium; m, megaspore; l, ligule. (From a
drawing kindly lent by Mrs D. H. Scott.)
B, C. Leaf with ligule. (From a section in Dr Kidston’s Collection.)
D. Transverse section of sporophyll. (After Scott.)
E. Radial section of microsporophyll of Bothrodendron. (From a section in the Manchester
Museum; Hick Collection R. 406.)
The slender stem, characterised by unequal dichotomy, has a single
protostele composed of scalariform tracheids with 3–6 peripheral
protoxylem groups. A zone of delicate tissue surrounds the xylem; this is
described as phloem, but it is not clear whether the designation is based on
histological characters or primarily on its position. The cortex consists of an
inner lacunar tissue and an outer region limited by a small-celled superficial
layer sharply contrasted with the underlying layers of larger cells. The stem
of Miadesmia is not uncommon in sections of the Lancashire calcareous
nodules, and may be recognised by the delicate crushed tissue of which it
mainly consists and by large hypodermal parenchyma. The spirally
Page 312
disposed leaves bear a conspicuous and relatively large ligule, 3 mm. long,
in a deep pit (fig. 219, B and C) roofed over by a few layers of tissue
corresponding to the velum in Isoetes (cf. fig. 133, E, v). The fairly thick
central region of the lamina is expanded laterally into thin wings, which in
the living state probably bore delicate hairs. These delicate leaves,
apparently without stomata, were attached to the stem at an acute angle, and
Miss Benson suggests that their form and arrangement may have enabled
them to hold water by surface-tension. As seen in fig. 219, B, C, which
represents part of a transverse section near the leaf-base, the ligule is a very
characteristic feature, and the size of the single vein is in keeping with the
almost filmy nature of the lamina.
In addition to the sections in British collections, I have been enabled by
the kindness of Prof. Bertrand to see photomicrographs of the sections on
which he founded the genus. One of these sections, transverse to the stem
and leaves, illustrates in a striking manner the relatively large size of the
leaves and ligules in proportion to the delicate axis of the shoot.
The megasporangiate cone has an axis which agrees in its structure with
that of the vegetative stem and bears several megasporophylls
approximately at right-angles. As in the foliage leaves, the ligule is
prominent and large, and lies in a groove which contains also the
megasporangium; both ligule, l, and sporangium, s, as seen in the transverse
section represented in fig. 219, D, are covered by an integument or velum
which arises in the proximal part of the leaf and leaves a circular micropylar
opening at the beak-like apex of the sporangium. The circular micropyle is
surrounded by numerous hairs borne on the integument and which
presumably played the part of a feathery stigma. A single megaspore with a
thin membrane, m, abuts on the fairly strong sporangial wall, s; in some
cases the sporangium and megaspore walls may be indistinguishable, a
feature suggesting comparison with seed-structure. Some megaspores have
been found filled with a prothallus. The longitudinal section shown in fig.
219, A, illustrates the characteristic horizontal position of the
megasporophyll, as also the relation of the ligule, l, to the sporophyll with
its single vascular bundle, and to the hairy integument, which overarches
both sporangium and ligule; the line m shows the position of the
megaspore-membrane, detached from the sporangial wall on the upper side
but in contact with it below. The microsporophyll shown in 219, E, was
in a deep pit (fig. 219, B and C) roofed over by a few layers of tissue
corresponding to the velum in Isoetes (cf. fig. 133, E, v). The fairly thick
central region of the lamina is expanded laterally into thin wings, which in
the living state probably bore delicate hairs. These delicate leaves,
apparently without stomata, were attached to the stem at an acute angle, and
Miss Benson suggests that their form and arrangement may have enabled
them to hold water by surface-tension. As seen in fig. 219, B, C, which
represents part of a transverse section near the leaf-base, the ligule is a very
characteristic feature, and the size of the single vein is in keeping with the
almost filmy nature of the lamina.
In addition to the sections in British collections, I have been enabled by
the kindness of Prof. Bertrand to see photomicrographs of the sections on
which he founded the genus. One of these sections, transverse to the stem
and leaves, illustrates in a striking manner the relatively large size of the
leaves and ligules in proportion to the delicate axis of the shoot.
The megasporangiate cone has an axis which agrees in its structure with
that of the vegetative stem and bears several megasporophylls
approximately at right-angles. As in the foliage leaves, the ligule is
prominent and large, and lies in a groove which contains also the
megasporangium; both ligule, l, and sporangium, s, as seen in the transverse
section represented in fig. 219, D, are covered by an integument or velum
which arises in the proximal part of the leaf and leaves a circular micropylar
opening at the beak-like apex of the sporangium. The circular micropyle is
surrounded by numerous hairs borne on the integument and which
presumably played the part of a feathery stigma. A single megaspore with a
thin membrane, m, abuts on the fairly strong sporangial wall, s; in some
cases the sporangium and megaspore walls may be indistinguishable, a
feature suggesting comparison with seed-structure. Some megaspores have
been found filled with a prothallus. The longitudinal section shown in fig.
219, A, illustrates the characteristic horizontal position of the
megasporophyll, as also the relation of the ligule, l, to the sporophyll with
its single vascular bundle, and to the hairy integument, which overarches
both sporangium and ligule; the line m shows the position of the
megaspore-membrane, detached from the sporangial wall on the upper side
but in contact with it below. The microsporophyll shown in 219, E, was
Page 313
originally referred to Miadesmia but has since been recognised by
Watson[673] as that of a Bothrostrobus.
Miadesmia affords an example of a Palaeozoic plant comparable with
Isoetes and Selaginella; it agrees also with Lepidocarpon in possessing true
seeds, and with Watson’s Bothrodendron cone in the shape of the sporangia,
which are more like those of Selaginella than the radially elongated
sporangia of Lepidostrobus. Miadesmia agrees with Selaginella, e.g. S.
spinosa, in its stelar structure, in the form of the sporangia, and in the
presence of a ligule. It is distinguished by having only one instead of four
megaspores in a sporangium, in the possession of an integument which
formed a close investment to the spore and served as a stigma (comparable
with the stigma-like integument of the male flower of Welwitschia), and in
the shedding of the megasporophylls, which have been aptly compared with
winged seeds.
LEPIDOCARPON
On the ground of their general anatomical features Lepidocarpon and
Miadesmia are clearly entitled to be included among extinct representatives
of the Pteridophyta. These plants had, however, crossed what it has been
customary to regard as the boundary between Pteridophytes and
Phanerogams: they possessed megasporangia with the attributes of seeds. It
has been suggested by Lester Ward[674] that Pteridophytic seed-bearing
plants shall be recognised as a distinct phylum for which he proposes the
name Pteridospermaphyta, a designation implying exclusion from the
Spermatophyta as usually understood. For seed-bearing Lycopodiaceous
genera he suggests the name Lepidospermae. As knowledge of the
Palaeozoic seed-plants increases revision of existing classifications and
group names will become necessary, but as yet we are hardly in a position
to draw up a satisfactory scheme of grouping; we know little of
Lepidocarpon as a whole and it would be premature to commit ourselves,
even provisionally, to a classification which is based on such meagre
evidence as we possess. Moreover the value to be attached to the seed-habit
as a basis of classification can hardly be estimated until fuller information is
obtained.
Watson[673] as that of a Bothrostrobus.
Miadesmia affords an example of a Palaeozoic plant comparable with
Isoetes and Selaginella; it agrees also with Lepidocarpon in possessing true
seeds, and with Watson’s Bothrodendron cone in the shape of the sporangia,
which are more like those of Selaginella than the radially elongated
sporangia of Lepidostrobus. Miadesmia agrees with Selaginella, e.g. S.
spinosa, in its stelar structure, in the form of the sporangia, and in the
presence of a ligule. It is distinguished by having only one instead of four
megaspores in a sporangium, in the possession of an integument which
formed a close investment to the spore and served as a stigma (comparable
with the stigma-like integument of the male flower of Welwitschia), and in
the shedding of the megasporophylls, which have been aptly compared with
winged seeds.
LEPIDOCARPON
On the ground of their general anatomical features Lepidocarpon and
Miadesmia are clearly entitled to be included among extinct representatives
of the Pteridophyta. These plants had, however, crossed what it has been
customary to regard as the boundary between Pteridophytes and
Phanerogams: they possessed megasporangia with the attributes of seeds. It
has been suggested by Lester Ward[674] that Pteridophytic seed-bearing
plants shall be recognised as a distinct phylum for which he proposes the
name Pteridospermaphyta, a designation implying exclusion from the
Spermatophyta as usually understood. For seed-bearing Lycopodiaceous
genera he suggests the name Lepidospermae. As knowledge of the
Palaeozoic seed-plants increases revision of existing classifications and
group names will become necessary, but as yet we are hardly in a position
to draw up a satisfactory scheme of grouping; we know little of
Lepidocarpon as a whole and it would be premature to commit ourselves,
even provisionally, to a classification which is based on such meagre
evidence as we possess. Moreover the value to be attached to the seed-habit
as a basis of classification can hardly be estimated until fuller information is
obtained.
Page 314
Page 315
CHAPTER XX.
FILICALES.
This division of the Pteridophyta includes both the true ferns (Filicineae)
and the less familiar water-ferns or Hydropterideae. The almost complete
absence of satisfactory evidence in regard to the geological history of the
latter renders this group of secondary importance from a palaeobotanical
standpoint, but, on the other hand, we possess a wealth of material bearing
on the past history and relative antiquity of the true ferns.
The study of extinct types has so far rendered no substantial help towards
bridging the wide gap between the Filicales and the lower plants. As Mr
Tansley[675] says in his admirable lectures on The Evolution of the Filicinean
Vascular System, “The biggest gap in the plant kingdom at the present time
is undoubtedly that which separates the Pteridophytes from the plants
definitely below them in organisation, and directly we try to step behind the
ferns we tumble into this abyss.” Resemblances long ago recognised
between certain ferns and the cycads, a section of the Gymnosperms, were
regarded by a few botanists as indications of blood-relationship, and the
results of recent researches into the morphological characters of extinct
Palaeozoic types are generally held to confirm these surmises. Prof.
Chodat[676] of Geneva has recently challenged the validity of the arguments
on which the affinity of cycads and ferns has been accepted by the great
majority of botanists. Whether or not his criticisms stand the test of
unbiassed examination, they must at least lead us to substitute a critical
consideration of the facts for a mere repetition of conclusions which appeal
to our imagination. Despite Prof. Chodat’s warning, we may still quote with
confidence a phrase used in another connexion—ferns “are links in a chain
and branches on the tree of life, with their roots in a past inconceivably
remote[677].”
PTERIDOSPERMS
FILICALES.
This division of the Pteridophyta includes both the true ferns (Filicineae)
and the less familiar water-ferns or Hydropterideae. The almost complete
absence of satisfactory evidence in regard to the geological history of the
latter renders this group of secondary importance from a palaeobotanical
standpoint, but, on the other hand, we possess a wealth of material bearing
on the past history and relative antiquity of the true ferns.
The study of extinct types has so far rendered no substantial help towards
bridging the wide gap between the Filicales and the lower plants. As Mr
Tansley[675] says in his admirable lectures on The Evolution of the Filicinean
Vascular System, “The biggest gap in the plant kingdom at the present time
is undoubtedly that which separates the Pteridophytes from the plants
definitely below them in organisation, and directly we try to step behind the
ferns we tumble into this abyss.” Resemblances long ago recognised
between certain ferns and the cycads, a section of the Gymnosperms, were
regarded by a few botanists as indications of blood-relationship, and the
results of recent researches into the morphological characters of extinct
Palaeozoic types are generally held to confirm these surmises. Prof.
Chodat[676] of Geneva has recently challenged the validity of the arguments
on which the affinity of cycads and ferns has been accepted by the great
majority of botanists. Whether or not his criticisms stand the test of
unbiassed examination, they must at least lead us to substitute a critical
consideration of the facts for a mere repetition of conclusions which appeal
to our imagination. Despite Prof. Chodat’s warning, we may still quote with
confidence a phrase used in another connexion—ferns “are links in a chain
and branches on the tree of life, with their roots in a past inconceivably
remote[677].”
PTERIDOSPERMS
Page 316
Transitional forms which are regarded as pointing to a common origin for
ferns and cycads are known in abundance; other types have also been
discovered which lead some authors to go so far as to derive the whole of
the seed-bearing plants from an ancestry the descendants of which are
represented by existing ferns. While hesitating to allow the ferns or fern-
like plants the peculiar position of universal ancestors, we must admit that
there is no group of plants with a history of greater importance from an
evolutionary standpoint than that with which we are now concerned.
There are, however, some difficulties to face in attempting to decipher
the history of the Filicineae as recorded in the earth’s crust. Few fossil
plants are so familiar as the well-preserved carbonaceous impressions of
compound leaves on the shales of our Coal-Measures, which were referred
by older authors to recent genera and species of ferns and accepted by later
writers as undoubted examples of Palaeozoic ferns. The common belief in
the dominance of ferns in Palaeozoic floras is reflected in the novelist’s
description of the Carboniferous period, “when the forms of plants were
few and often of the fern kind[678].” We now know that very many of these
Carboniferous leaves belonged to plants differing widely in morphological
characters from the modern genera to which they exhibit so deceptive a
resemblance. These pseudo-ferns, recently christened Pteridosperms or
seed-bearing fern-like plants, are dealt with in a later chapter. The discovery
of this extinct group has added enormously to our knowledge of plant-
evolution and at the same time has rendered much more difficult the task of
unravelling the past history of the true ferns. As soon as it was
demonstrated that many familiar Palaeozoic “ferns” are not ferns, some
authors went far towards concluding that however close might be the
agreement between fossil and recent leaves suspicion of close relationship
must be set aside. Like the earlier writers who described fossils as lusus
naturae fashioned by devilish agency to deceive too credulous man, the
discovery of seed-bearing plants with the foliage of ferns threatened to
disturb the mental balance of palaeobotanists. The fact is, we cannot in
some cases determine from leaf-form alone whether or not a fossil is a true
fern; we may, as Professor Bower[679] suggests, regard all fern-like fossils as
ferns until they are proved to be Pteridosperms, or in a spirit of scientific
scepticism, we may at once admit that many Palaeozoic fern-like leaves
must await further evidence before their true position can be determined. It
is impossible, as Zeiller[680] says, in the present state of our knowledge to
ferns and cycads are known in abundance; other types have also been
discovered which lead some authors to go so far as to derive the whole of
the seed-bearing plants from an ancestry the descendants of which are
represented by existing ferns. While hesitating to allow the ferns or fern-
like plants the peculiar position of universal ancestors, we must admit that
there is no group of plants with a history of greater importance from an
evolutionary standpoint than that with which we are now concerned.
There are, however, some difficulties to face in attempting to decipher
the history of the Filicineae as recorded in the earth’s crust. Few fossil
plants are so familiar as the well-preserved carbonaceous impressions of
compound leaves on the shales of our Coal-Measures, which were referred
by older authors to recent genera and species of ferns and accepted by later
writers as undoubted examples of Palaeozoic ferns. The common belief in
the dominance of ferns in Palaeozoic floras is reflected in the novelist’s
description of the Carboniferous period, “when the forms of plants were
few and often of the fern kind[678].” We now know that very many of these
Carboniferous leaves belonged to plants differing widely in morphological
characters from the modern genera to which they exhibit so deceptive a
resemblance. These pseudo-ferns, recently christened Pteridosperms or
seed-bearing fern-like plants, are dealt with in a later chapter. The discovery
of this extinct group has added enormously to our knowledge of plant-
evolution and at the same time has rendered much more difficult the task of
unravelling the past history of the true ferns. As soon as it was
demonstrated that many familiar Palaeozoic “ferns” are not ferns, some
authors went far towards concluding that however close might be the
agreement between fossil and recent leaves suspicion of close relationship
must be set aside. Like the earlier writers who described fossils as lusus
naturae fashioned by devilish agency to deceive too credulous man, the
discovery of seed-bearing plants with the foliage of ferns threatened to
disturb the mental balance of palaeobotanists. The fact is, we cannot in
some cases determine from leaf-form alone whether or not a fossil is a true
fern; we may, as Professor Bower[679] suggests, regard all fern-like fossils as
ferns until they are proved to be Pteridosperms, or in a spirit of scientific
scepticism, we may at once admit that many Palaeozoic fern-like leaves
must await further evidence before their true position can be determined. It
is impossible, as Zeiller[680] says, in the present state of our knowledge to
Page 317
range fern-like Palaeozoic plants in two groups, one referred to Filicineae
and the other to the Pteridosperms.
The following classification of the Filicales is based on that adopted by
Prof. Engler in the latest edition of his Syllabus[681] and on the results of
Bower’s[682] excellent work on the spore-bearing members of recent ferns.
The members of the Filicales are characterised by the same well-marked
physiological division of labour in their vegetative parts as are the
Lycopods; the plant is the asexual generation (sporophyte), while the sexual
generation (gametophyte) is small and inconspicuous, either an independent
green prothallus or a tissue more or less completely enclosed in the spore.
The large size of the leaves, which in the young state are usually coiled like
a crozier (fig. 220, A), is a striking characteristic of the ferns; they are
megaphyllous in contrast to the microphylly of the Lycopods.
I. Leptosporangiate Filicales.
In these homosporous and heterosporous plants the sporangia are
developed from single epidermal cells.
and the other to the Pteridosperms.
The following classification of the Filicales is based on that adopted by
Prof. Engler in the latest edition of his Syllabus[681] and on the results of
Bower’s[682] excellent work on the spore-bearing members of recent ferns.
The members of the Filicales are characterised by the same well-marked
physiological division of labour in their vegetative parts as are the
Lycopods; the plant is the asexual generation (sporophyte), while the sexual
generation (gametophyte) is small and inconspicuous, either an independent
green prothallus or a tissue more or less completely enclosed in the spore.
The large size of the leaves, which in the young state are usually coiled like
a crozier (fig. 220, A), is a striking characteristic of the ferns; they are
megaphyllous in contrast to the microphylly of the Lycopods.
I. Leptosporangiate Filicales.
In these homosporous and heterosporous plants the sporangia are
developed from single epidermal cells.
Page 318
Fig. 220. Young fronds of (A) Angiopteris evecta and (B) Cycas revoluta. (Reduced.)
(a) Eufilicineae. The sporangia bear spores of one kind only; the wall of a
sporangium consists of one layer of cells. In the great majority of cases the
sporangia are characterised by the possession of a conspicuous row of
thick-walled brown cells, the annulus[683], which serves as a mechanism for
dehiscence and spore-dispersal. The fertile leaves, identical in form with the
sterile, or more or less sharply contrasted, usually bear the sporangia on the
under surface of the lamina in definite groups or sori, and not on the upper
surface or grouped in strobili as in the Lycopodiales. The stem is
dorsiventral or radial in structure, creeping or erect, frequently clothed with
chaffy scales (ramenta) and less often with multicellular hairs. The sexual
(a) Eufilicineae. The sporangia bear spores of one kind only; the wall of a
sporangium consists of one layer of cells. In the great majority of cases the
sporangia are characterised by the possession of a conspicuous row of
thick-walled brown cells, the annulus[683], which serves as a mechanism for
dehiscence and spore-dispersal. The fertile leaves, identical in form with the
sterile, or more or less sharply contrasted, usually bear the sporangia on the
under surface of the lamina in definite groups or sori, and not on the upper
surface or grouped in strobili as in the Lycopodiales. The stem is
dorsiventral or radial in structure, creeping or erect, frequently clothed with
chaffy scales (ramenta) and less often with multicellular hairs. The sexual
Page 319
generation is represented by a small green prothallus which lives for a short
period only and dies after nursing the fern-plant through its earliest stages.
(b) Hydropterideae. Heterosporous water-ferns differing considerably in
habit from the true ferns. Each megasporangium contains a single
megaspore and several microspores are produced in each microsporangium.
The gametophyte is represented by tissue more or less enclosed in the
spore. [Genera Salvinia, Azolla, Marsilia, Regnellidium, Pilularia. See
Chapter xxvi.]
Eufilicineae.
The classification of the true ferns in common use is based almost
exclusively on the structure of the sporangium, the form and position of the
sori, and on the presence or absence of an indusium (the tissue which in
some ferns partially or completely covers each sorus). In recent years there
has been considerable activity in the investigation of fern anatomy with a
view to elucidating the natural relationship between recent families or
genera. The results of these researches are on the whole consistent with the
scheme and grouping adopted in the Synopsis Filicum of Hooker and Baker
and in general harmony with the main conclusions arrived at by Bower
from an intensive study of the development of fern sporangia. The
following classification is based on that of Bower who takes as a basis (i)
the relative time of appearance of the sporangia in a single sorus, (ii) the
structure of the sporangia and their orientation relative to the whole sorus,
(iii) the productiveness of sporangia (spore-output).
Osmundaceae
Simplices (Bower). The sporangia are relatively
Schizaeaceae
large and all the sporangia in a sorus have a
Gleicheniaceae
simultaneous origin: the annulus is oblique.
Matonineae
Gradatae (Bower). Sporangia arise in basipetal
succession on a more or less elongated receptacle
Loxsomaceae
(portion of the leaf lamina which projects as a
Hymenophyllaceae
cushion or column on which the sporangia are
Cyatheaceae
borne); annulus oblique; indusium, if present, in
Dennstaedtiinae
the form of a cup or flap of tissue arising from
the base of the sorus.
period only and dies after nursing the fern-plant through its earliest stages.
(b) Hydropterideae. Heterosporous water-ferns differing considerably in
habit from the true ferns. Each megasporangium contains a single
megaspore and several microspores are produced in each microsporangium.
The gametophyte is represented by tissue more or less enclosed in the
spore. [Genera Salvinia, Azolla, Marsilia, Regnellidium, Pilularia. See
Chapter xxvi.]
Eufilicineae.
The classification of the true ferns in common use is based almost
exclusively on the structure of the sporangium, the form and position of the
sori, and on the presence or absence of an indusium (the tissue which in
some ferns partially or completely covers each sorus). In recent years there
has been considerable activity in the investigation of fern anatomy with a
view to elucidating the natural relationship between recent families or
genera. The results of these researches are on the whole consistent with the
scheme and grouping adopted in the Synopsis Filicum of Hooker and Baker
and in general harmony with the main conclusions arrived at by Bower
from an intensive study of the development of fern sporangia. The
following classification is based on that of Bower who takes as a basis (i)
the relative time of appearance of the sporangia in a single sorus, (ii) the
structure of the sporangia and their orientation relative to the whole sorus,
(iii) the productiveness of sporangia (spore-output).
Osmundaceae
Simplices (Bower). The sporangia are relatively
Schizaeaceae
large and all the sporangia in a sorus have a
Gleicheniaceae
simultaneous origin: the annulus is oblique.
Matonineae
Gradatae (Bower). Sporangia arise in basipetal
succession on a more or less elongated receptacle
Loxsomaceae
(portion of the leaf lamina which projects as a
Hymenophyllaceae
cushion or column on which the sporangia are
Cyatheaceae
borne); annulus oblique; indusium, if present, in
Dennstaedtiinae
the form of a cup or flap of tissue arising from
the base of the sorus.
Page 320
Mixtae (Bower). This division includes the
Polypodiaceae, by far the largest family of ferns.
The sporangia are characterised by their
Polypodiaceae
relatively small size, the presence of a slender
Parkeriaceae
stalk, the absence of regular orientation or
sequence in development, and by the presence of
a vertical annulus.
The Dipteridinae include species with the characters
Dipteridinae of the Mixtae, and one species in which the
sporangia develope simultaneously (Simplices).
Osmundaceae[684]. (Osmunda, Todea.)
Sporangia large and rather stouter than those of other Leptosporangiate
ferns, borne in small groups (filmy species of Todea) in linear and
frequently confluent sori (Todea barbara; fig. 221, D) or clustered round
the axis of modified fertile pinnae with much reduced lamina (Osmunda).
The annulus is represented by a group of thicker-walled cells a short
distance below the apex (fig. 221, C). This family stands apart among the
ferns; in some respects, e.g. in the more robust sporangia occasionally
forming synangia, and in the presence of stipular wings, it forms a
transitional series between the Leptosporangiate and Eusporangiate ferns.
The only European species of Osmunda, O. regalis, is almost cosmopolitan
in range; other species occur in North and South America, in the Far East,
the Malay Peninsula, and in other regions, more especially in the temperate
zones. Todea is represented by (i) the South African and Australian species,
T. barbara, a fern with a stem, which may reach a height of several feet,
thickly covered with adventitious roots and bearing large and somewhat
leathery fronds; (ii) filmy species in New Zealand, New South Wales, New
Caledonia, and elsewhere. A plant of the small tree-fern Todea Wilkesiana
(Fiji, Samoa, and other islands) in the filmy-fern house at Kew, to which
my attention was drawn by my friend Mr A. W. Hill, has a slender stem
with the characteristic leaf-scars exposed; it presents a striking similarity to
some of the fossil species of Osmundaceae described in a later chapter.
Polypodiaceae, by far the largest family of ferns.
The sporangia are characterised by their
Polypodiaceae
relatively small size, the presence of a slender
Parkeriaceae
stalk, the absence of regular orientation or
sequence in development, and by the presence of
a vertical annulus.
The Dipteridinae include species with the characters
Dipteridinae of the Mixtae, and one species in which the
sporangia develope simultaneously (Simplices).
Osmundaceae[684]. (Osmunda, Todea.)
Sporangia large and rather stouter than those of other Leptosporangiate
ferns, borne in small groups (filmy species of Todea) in linear and
frequently confluent sori (Todea barbara; fig. 221, D) or clustered round
the axis of modified fertile pinnae with much reduced lamina (Osmunda).
The annulus is represented by a group of thicker-walled cells a short
distance below the apex (fig. 221, C). This family stands apart among the
ferns; in some respects, e.g. in the more robust sporangia occasionally
forming synangia, and in the presence of stipular wings, it forms a
transitional series between the Leptosporangiate and Eusporangiate ferns.
The only European species of Osmunda, O. regalis, is almost cosmopolitan
in range; other species occur in North and South America, in the Far East,
the Malay Peninsula, and in other regions, more especially in the temperate
zones. Todea is represented by (i) the South African and Australian species,
T. barbara, a fern with a stem, which may reach a height of several feet,
thickly covered with adventitious roots and bearing large and somewhat
leathery fronds; (ii) filmy species in New Zealand, New South Wales, New
Caledonia, and elsewhere. A plant of the small tree-fern Todea Wilkesiana
(Fiji, Samoa, and other islands) in the filmy-fern house at Kew, to which
my attention was drawn by my friend Mr A. W. Hill, has a slender stem
with the characteristic leaf-scars exposed; it presents a striking similarity to
some of the fossil species of Osmundaceae described in a later chapter.
Page 321
Fig. 221.
A. Osmunda cinnamomea (after Faull).
B. Todea barbara, p, phloem; s, sclerenchyma.
C. Osmunda regalis (after Luerssen).
D. Todea barbara (½ nat. size).
Schizaeaceae. (Schizaea, Aneimia, Lygodium, Mohria.)
Sporangia borne singly and not in groups (sori), readily recognised by the
complete transverse apical annulus usually one layer of cells deep, but
occasionally two layers in depth on the side opposite the line of
dehiscence[685] (fig. 224, B). Schizaea (fig. 222) with the exception of one
species in North America (S. pusilla) is characteristic of Northern India, the
Malay region, Australia, New Caledonia, S. Africa, and elsewhere south of
the Equator. Aneimia (figs. 223, 224, A, B), characterised by the fertile
segments with reduced lamina, is chiefly American: the monotypic genus
Mohria, resembling in habit the Polypodiaceous genus Cheilanthes, occurs
in S. Africa and Madagascar, while species of Lygodium are widely spread
A. Osmunda cinnamomea (after Faull).
B. Todea barbara, p, phloem; s, sclerenchyma.
C. Osmunda regalis (after Luerssen).
D. Todea barbara (½ nat. size).
Schizaeaceae. (Schizaea, Aneimia, Lygodium, Mohria.)
Sporangia borne singly and not in groups (sori), readily recognised by the
complete transverse apical annulus usually one layer of cells deep, but
occasionally two layers in depth on the side opposite the line of
dehiscence[685] (fig. 224, B). Schizaea (fig. 222) with the exception of one
species in North America (S. pusilla) is characteristic of Northern India, the
Malay region, Australia, New Caledonia, S. Africa, and elsewhere south of
the Equator. Aneimia (figs. 223, 224, A, B), characterised by the fertile
segments with reduced lamina, is chiefly American: the monotypic genus
Mohria, resembling in habit the Polypodiaceous genus Cheilanthes, occurs
in S. Africa and Madagascar, while species of Lygodium are widely spread
Page 322
tropical ferns, with one species in temperate North America. This family
has disappeared from Europe.
Fig. 222. Schizaea elegans. (Slightly reduced.) A few of the segments terminate in narrow
fertile lobes.
has disappeared from Europe.
Fig. 222. Schizaea elegans. (Slightly reduced.) A few of the segments terminate in narrow
fertile lobes.
Page 323
Fig. 223. Aneimia rotundifolia. (From the Royal Gardens, Kew. ⅓ nat. size.)
Gleicheniaceae [Gleichenia, Platyzoma (= G. microphylla)].
Sporangia form circular naked sori composed of a variable number of
sporangia, usually not more than ten and frequently fewer, characterised by
an obliquely horizontal and almost complete annulus (fig. 224, I). In some
species of Gleichenia (sect. Eugleichenia) the ultimate segments are very
small and semicircular in form (fig. 226, C), in others (sect. Mertensia[686])
the segments are linear (fig. 226, D), and in many species the fronds are
distinguished by the regular dichotomous branching (fig. 225), frequently
Gleicheniaceae [Gleichenia, Platyzoma (= G. microphylla)].
Sporangia form circular naked sori composed of a variable number of
sporangia, usually not more than ten and frequently fewer, characterised by
an obliquely horizontal and almost complete annulus (fig. 224, I). In some
species of Gleichenia (sect. Eugleichenia) the ultimate segments are very
small and semicircular in form (fig. 226, C), in others (sect. Mertensia[686])
the segments are linear (fig. 226, D), and in many species the fronds are
distinguished by the regular dichotomous branching (fig. 225), frequently
Page 324
showing an arrested rachis bud in the forks[687] protected by modified
pinnules (fig. 226, D, E). In Platyzoma the leaves are simple, reaching a
length of 20–30 cm., and bear small revolute oval segments.
Fig. 224.
A. Aneimia flexuosa.
B. A. phyllitidis.
C. Hymenophyllum dilatatum.
D, E, F, G. Matonia pectinata; i, indusium.
H. Thyrsopteris elegans.
I. Gleichenia circinata.
(A, B, after Prantl; C, G, H, I, after Bower.)
pinnules (fig. 226, D, E). In Platyzoma the leaves are simple, reaching a
length of 20–30 cm., and bear small revolute oval segments.
Fig. 224.
A. Aneimia flexuosa.
B. A. phyllitidis.
C. Hymenophyllum dilatatum.
D, E, F, G. Matonia pectinata; i, indusium.
H. Thyrsopteris elegans.
I. Gleichenia circinata.
(A, B, after Prantl; C, G, H, I, after Bower.)
Page 325
Fig. 225. Gleichenia dicarpa. (⅓ nat. size.)
Page 326
Fig. 226.
A, B. Gleichenites Rostafinskii, Raciborski.
C. Gleichenia dicarpa. (Nat. size.)
D, E. Gleichenia dichotoma. (Reduced.)
(A, B, after Raciborski; C, after Hooker; D, E, after Goebel.)
Gleichenia is represented by several species in the tropics and extends to
south temperate and Antarctic latitudes. The species G. dichotoma (= G.
linearis) is one of the more successful tropical ferns, while G. moniliformis
(by some authors recognised as a distinct genus, Stromatopteris) is peculiar
to New Caledonia. The monotypic genus Platyzoma is a xerophilous
Australian fern. The Gleicheniaceae are unrepresented in existing north
temperate floras.
Matonineae. (Matonia.)
The genus Matonia, placed in the Cyatheaceae by Sir William Hooker
and compared by other authors also with the Gleicheniaceae, is now
included in a special family. The sori are circular and consist of 5–11 large
sporangia (fig. 224, E, G) sessile on a central columnar receptacle which
spreads out into an umbrella-like indusium (D, i) with its incurved margin
A, B. Gleichenites Rostafinskii, Raciborski.
C. Gleichenia dicarpa. (Nat. size.)
D, E. Gleichenia dichotoma. (Reduced.)
(A, B, after Raciborski; C, after Hooker; D, E, after Goebel.)
Gleichenia is represented by several species in the tropics and extends to
south temperate and Antarctic latitudes. The species G. dichotoma (= G.
linearis) is one of the more successful tropical ferns, while G. moniliformis
(by some authors recognised as a distinct genus, Stromatopteris) is peculiar
to New Caledonia. The monotypic genus Platyzoma is a xerophilous
Australian fern. The Gleicheniaceae are unrepresented in existing north
temperate floras.
Matonineae. (Matonia.)
The genus Matonia, placed in the Cyatheaceae by Sir William Hooker
and compared by other authors also with the Gleicheniaceae, is now
included in a special family. The sori are circular and consist of 5–11 large
sporangia (fig. 224, E, G) sessile on a central columnar receptacle which
spreads out into an umbrella-like indusium (D, i) with its incurved margin
Page 327
tucked in below the ring of sporangia. The indusium is detached when the
sporangia are ripe. The annulus is oblique and incomplete and often slightly
sinuous; it agrees in the main with that of Gleichenia. The species Matonia
pectinata is characterised by dichotomously branched fronds (figs. 227,
228) with long and slender petioles; the pinnae bear linear pinnules with
forked lateral veins and occasional lateral anastomoses (fig. 224, F). The
only other living representative is M. sarmentosa, discovered by Mr Charles
Hose at Niah, Sarawak[688]: this species has long pendulous leaves
apparently very different from those of M. pectinata, but the branching of
the frond may be regarded as a modification of a primitive form of
dichotomy[689]. A small bud occurs in the angle between the forked linear
segments and the rachis, as in some species of Gleichenia[690]. Matonia is
confined to the Malay region: M. pectinata grows in Western Borneo and in
various localities in the Malay peninsula, while M. sarmentosa, has been
found in one locality only; the latter species has recently been transferred to
a new genus Phanerosorus, but in view of the practical identity in
anatomical structure and the close agreement as regards the sori of the two
species there would seem to be no justification for this change of name[691].
sporangia are ripe. The annulus is oblique and incomplete and often slightly
sinuous; it agrees in the main with that of Gleichenia. The species Matonia
pectinata is characterised by dichotomously branched fronds (figs. 227,
228) with long and slender petioles; the pinnae bear linear pinnules with
forked lateral veins and occasional lateral anastomoses (fig. 224, F). The
only other living representative is M. sarmentosa, discovered by Mr Charles
Hose at Niah, Sarawak[688]: this species has long pendulous leaves
apparently very different from those of M. pectinata, but the branching of
the frond may be regarded as a modification of a primitive form of
dichotomy[689]. A small bud occurs in the angle between the forked linear
segments and the rachis, as in some species of Gleichenia[690]. Matonia is
confined to the Malay region: M. pectinata grows in Western Borneo and in
various localities in the Malay peninsula, while M. sarmentosa, has been
found in one locality only; the latter species has recently been transferred to
a new genus Phanerosorus, but in view of the practical identity in
anatomical structure and the close agreement as regards the sori of the two
species there would seem to be no justification for this change of name[691].
Page 328
Fig. 227. Matonia pectinata. (⅕ nat. size.) M.S.
Loxsomaceae.
The New Zealand genus Loxsoma has marginal sori with a cup-like
indusium surrounding an elongated receptacle bearing pear-shaped
sporangia provided with a complete oblique annulus. The genus is chiefly
interesting because of its isolated position; it agrees with Trichomanes
(Hymenophyllaceae) in the structure of the sorus and with species of
Dicksonia and Davallia in habit; it shows some resemblance also to
Gleicheniaceae and Schizaeaceae[692]. A new type of fern described by
Loxsomaceae.
The New Zealand genus Loxsoma has marginal sori with a cup-like
indusium surrounding an elongated receptacle bearing pear-shaped
sporangia provided with a complete oblique annulus. The genus is chiefly
interesting because of its isolated position; it agrees with Trichomanes
(Hymenophyllaceae) in the structure of the sorus and with species of
Dicksonia and Davallia in habit; it shows some resemblance also to
Gleicheniaceae and Schizaeaceae[692]. A new type of fern described by
Page 329
Christ[693] from Costa Rica as Loxsomopsis costaricensis affords a striking
instance of discontinuous distribution and emphasises the antiquity and
generalised features of the family.
Fig. 228. Matonia pectinata. From a photograph by Mr Tansley of a group of plants in a
wood on Gunong Tundok, Mount Ophir.
Hymenophyllaceae. (Hymenophyllum, Trichomanes.)
The sporangia, which are attached to a columnar receptacle or
prolongation of a vein beyond the margin of the lamina, are characterised
by an obliquely transverse annulus (fig. 224, C). A cup-like indusium
surrounds the lower portion of the receptacle which is two-lipped in
Trichomanes and entire in Hymenophyllum (fig. 270, C, D). These two
filmy ferns have a wide distribution both in tropical and extra-tropical
instance of discontinuous distribution and emphasises the antiquity and
generalised features of the family.
Fig. 228. Matonia pectinata. From a photograph by Mr Tansley of a group of plants in a
wood on Gunong Tundok, Mount Ophir.
Hymenophyllaceae. (Hymenophyllum, Trichomanes.)
The sporangia, which are attached to a columnar receptacle or
prolongation of a vein beyond the margin of the lamina, are characterised
by an obliquely transverse annulus (fig. 224, C). A cup-like indusium
surrounds the lower portion of the receptacle which is two-lipped in
Trichomanes and entire in Hymenophyllum (fig. 270, C, D). These two
filmy ferns have a wide distribution both in tropical and extra-tropical
Page 330
regions; they are represented in the British Isles by Hymenophyllum
tunbrigense, H. Wilsoni, and Trichomanes radicans.
Fig. 229.
A. Thyrsopteris elegans.
B. Cyathea spinulosa.
C. Davallia concinna.
D. Dicksonia coniifolia.
E. Alsophila excelsa.
F, G. Dicksonia culcita.
(A, after Diels and Kunze; B, D, F, G, after Hooker; E, after Bower.)
Cyatheaceae. (Cyathea, Hemitelia, Alsophila, Dicksonia,
Thyrsopteris.)
The sporangia occur in indusiate or naked sori and have an obliquely
vertical and incomplete annulus (fig. 229, E). In the great majority of cases
the fronds are large and highly compound, but Cyathea sinuata Hook, a rare
tunbrigense, H. Wilsoni, and Trichomanes radicans.
Fig. 229.
A. Thyrsopteris elegans.
B. Cyathea spinulosa.
C. Davallia concinna.
D. Dicksonia coniifolia.
E. Alsophila excelsa.
F, G. Dicksonia culcita.
(A, after Diels and Kunze; B, D, F, G, after Hooker; E, after Bower.)
Cyatheaceae. (Cyathea, Hemitelia, Alsophila, Dicksonia,
Thyrsopteris.)
The sporangia occur in indusiate or naked sori and have an obliquely
vertical and incomplete annulus (fig. 229, E). In the great majority of cases
the fronds are large and highly compound, but Cyathea sinuata Hook, a rare
Page 331
Ceylon species, bears simple narrow linear leaves. This family includes,
with few exceptions, all the tree ferns[694]. The sori of Dicksonia are
enclosed in a two-valved indusium (fig. 229, F. G); in the species
represented in fig. 230 the fertile segments, which terminate in cup-like
indusia, are characterised by the absence of a lamina and closely resemble
those of Thyrsopteris (fig. 229, A). In Cyathea the indusium has the form of
a cup which is at first closed and afterwards opens at the apex (fig. 229, B);
in Hemitelia the indusium is much reduced and in Alsophila the sori are
naked. Thyrsopteris is characterised by the reduced fertile pinnules bearing
stalked sori in deep cups (fig. 229, A). The appearance of this fern “is very
remarkable, for the cup-shaped sori hang down from the fronds in masses,
looking just like masses of millet seed[695].” The sporangia are described by
Bower[696] as large and of rather peculiar form. As seen in fig. 224, H, the
annulus is continuous; it forms a twisted loop of cells which vary in shape
and in the thickness of the walls. The Cyatheaceae are for the most part
tropical ferns with a wide geographical range, usually in moist regions; they
are, however, able to flourish under widely different temperature
conditions. In Tasmania, as Diels[697] points out, tree ferns may occasionally
be seen laden with snow, and on the west coast of New Zealand they
overhang the edge of a glacier[698]. The monotypic genus Thyrsopteris is
confined to Juan Fernandez. The Cyatheaceae no longer exist in Europe.
with few exceptions, all the tree ferns[694]. The sori of Dicksonia are
enclosed in a two-valved indusium (fig. 229, F. G); in the species
represented in fig. 230 the fertile segments, which terminate in cup-like
indusia, are characterised by the absence of a lamina and closely resemble
those of Thyrsopteris (fig. 229, A). In Cyathea the indusium has the form of
a cup which is at first closed and afterwards opens at the apex (fig. 229, B);
in Hemitelia the indusium is much reduced and in Alsophila the sori are
naked. Thyrsopteris is characterised by the reduced fertile pinnules bearing
stalked sori in deep cups (fig. 229, A). The appearance of this fern “is very
remarkable, for the cup-shaped sori hang down from the fronds in masses,
looking just like masses of millet seed[695].” The sporangia are described by
Bower[696] as large and of rather peculiar form. As seen in fig. 224, H, the
annulus is continuous; it forms a twisted loop of cells which vary in shape
and in the thickness of the walls. The Cyatheaceae are for the most part
tropical ferns with a wide geographical range, usually in moist regions; they
are, however, able to flourish under widely different temperature
conditions. In Tasmania, as Diels[697] points out, tree ferns may occasionally
be seen laden with snow, and on the west coast of New Zealand they
overhang the edge of a glacier[698]. The monotypic genus Thyrsopteris is
confined to Juan Fernandez. The Cyatheaceae no longer exist in Europe.
Page 332
Fig. 230. Dicksonia Bertercana Hook. Fertile and sterile pinnae. (Nat. size. British Museum
Herbarium.)
Dennstaedtiinae. (Microlepia, Dennstaedtia.)
This sub-tribe, instituted by Prantl, has been revived by Bower on the
ground that the sori present features intermediate between those of
Cyatheaceae and the Polypodiaceous genus Davallia. The sporangia have a
slightly oblique annulus.
Polypodiaceae.
Herbarium.)
Dennstaedtiinae. (Microlepia, Dennstaedtia.)
This sub-tribe, instituted by Prantl, has been revived by Bower on the
ground that the sori present features intermediate between those of
Cyatheaceae and the Polypodiaceous genus Davallia. The sporangia have a
slightly oblique annulus.
Polypodiaceae.
Page 333
This section of the Leptosporangiate ferns, including several sub-tribes,
comprises the great majority of recent genera. The sporangia form naked or
indusiate sori and have a vertical incomplete annulus. In Plagiogyria[699] the
oblique annulus and soral features suggest comparison with the
Cyatheaceae. A more intimate acquaintance with Polypodiaceous ferns will
undoubtedly demonstrate the existence of other generalised types[700].
From the point of view of the identification of fossil ferns it is important
to bear in mind the very close resemblance presented by some
Polypodiaceous species, e.g. species of Davallia (fig. 229, C), to
Cyatheaceous ferns (cf. fig. 229, D).
Parkeriaceae. (Ceratopteris.)
The almost spherical and scattered sporangia are characterised by the
peculiar form of the vertical annulus, which is composed of numerous cells
differing in their greater breadth and smaller depth from those of a typical
annulus. Exannulate sporangia have been described, while others occur
showing different stages between a rudimentary and a complete ring. The
single species of Ceratopteris, C. thalictroides, is an annual aquatic fern
widely spread in tropical countries[701].
comprises the great majority of recent genera. The sporangia form naked or
indusiate sori and have a vertical incomplete annulus. In Plagiogyria[699] the
oblique annulus and soral features suggest comparison with the
Cyatheaceae. A more intimate acquaintance with Polypodiaceous ferns will
undoubtedly demonstrate the existence of other generalised types[700].
From the point of view of the identification of fossil ferns it is important
to bear in mind the very close resemblance presented by some
Polypodiaceous species, e.g. species of Davallia (fig. 229, C), to
Cyatheaceous ferns (cf. fig. 229, D).
Parkeriaceae. (Ceratopteris.)
The almost spherical and scattered sporangia are characterised by the
peculiar form of the vertical annulus, which is composed of numerous cells
differing in their greater breadth and smaller depth from those of a typical
annulus. Exannulate sporangia have been described, while others occur
showing different stages between a rudimentary and a complete ring. The
single species of Ceratopteris, C. thalictroides, is an annual aquatic fern
widely spread in tropical countries[701].
Page 334
Fig. 231.
A, A′. Dipteris quinquefurcata (type-specimen in the Kew Herbarium).
B, C, E, G. D. conjugata. (C, ⅛ nat. size.)
D. Polypodium quercifolium.
F. Dipteris Wallichii.
(D, after Luerssen.)
Dipteridinae. (Dipteris.)
The genus Dipteris, formerly included in the Polypodiaceae, has been
assigned to a separate family partly on account of the slight obliquity of the
vertical annulus (fig. 231, G) and on other grounds[702]. The four species
A, A′. Dipteris quinquefurcata (type-specimen in the Kew Herbarium).
B, C, E, G. D. conjugata. (C, ⅛ nat. size.)
D. Polypodium quercifolium.
F. Dipteris Wallichii.
(D, after Luerssen.)
Dipteridinae. (Dipteris.)
The genus Dipteris, formerly included in the Polypodiaceae, has been
assigned to a separate family partly on account of the slight obliquity of the
vertical annulus (fig. 231, G) and on other grounds[702]. The four species
Page 335
Dipteris conjugata, D. Wallichii, D. Lobbiana (= D. bifurcata), and D.
quinquefurcata (fig. 231) are characterised by a creeping rhizome bearing
fronds reaching a length of 50 cm.; in D. conjugata and D. Wallichii the
lamina is divided by a median sinus into two symmetrical halves, while in
other species the leaf is dissected into narrow linear segments. The main
dichotomously branched ribs are connected by lateral branches and these by
tertiary veins, the delicate branches of which end freely within the square or
polygonal areolae (fig. 231, A′, E). The naked sori are composed of
numerous sporangia and filamentous hairs: while in some species the soral
development conforms to that characteristic of the Mixtae, it has been
shown that in one species, D. Lobbiana (= D. bifurcata[703]), the sporangia
develope simultaneously as in the Simplices. Dipteris occurs in company
with Matonia on Mt Ophir and elsewhere in the Malay peninsula; it extends
to the Philippines, Samoa, New Caledonia, China, New Guinea, and the
subtropical regions of Northern India.
• • • • •
The impossibility of drawing a hard and fast line between the divisions
adopted in any system of classification is well illustrated by the ferns. In the
main, the three-fold grouping suggested by Bower is probably consistent
with the order of evolution of the true ferns. The Polypodiaceae, which are
now the dominant group, are in all probability of comparatively recent
origin, while the Gradatae and Simplices represent smaller subdivisions
with representatives in remote geological epochs. The genera Loxsoma,
Matonia and Dipteris afford examples of ferns exhibiting points of contact
with more than one of Bower’s subdivisions: they are generalised types
which, like many relics of the past, are now characterised by a restricted
geographical range.
RECENT FERNS
quinquefurcata (fig. 231) are characterised by a creeping rhizome bearing
fronds reaching a length of 50 cm.; in D. conjugata and D. Wallichii the
lamina is divided by a median sinus into two symmetrical halves, while in
other species the leaf is dissected into narrow linear segments. The main
dichotomously branched ribs are connected by lateral branches and these by
tertiary veins, the delicate branches of which end freely within the square or
polygonal areolae (fig. 231, A′, E). The naked sori are composed of
numerous sporangia and filamentous hairs: while in some species the soral
development conforms to that characteristic of the Mixtae, it has been
shown that in one species, D. Lobbiana (= D. bifurcata[703]), the sporangia
develope simultaneously as in the Simplices. Dipteris occurs in company
with Matonia on Mt Ophir and elsewhere in the Malay peninsula; it extends
to the Philippines, Samoa, New Caledonia, China, New Guinea, and the
subtropical regions of Northern India.
• • • • •
The impossibility of drawing a hard and fast line between the divisions
adopted in any system of classification is well illustrated by the ferns. In the
main, the three-fold grouping suggested by Bower is probably consistent
with the order of evolution of the true ferns. The Polypodiaceae, which are
now the dominant group, are in all probability of comparatively recent
origin, while the Gradatae and Simplices represent smaller subdivisions
with representatives in remote geological epochs. The genera Loxsoma,
Matonia and Dipteris afford examples of ferns exhibiting points of contact
with more than one of Bower’s subdivisions: they are generalised types
which, like many relics of the past, are now characterised by a restricted
geographical range.
RECENT FERNS
Page 336
Fig. 232. Davallia aculeata. (⅖ nat. size.)
It is noteworthy that while certain vegetative features may in some cases
be cited as family-characters, such features are not usually of much value
from a taxonomic point of view. While the typical tree ferns are practically
all members of the Cyatheaceae, a few members of other families, e.g.
Todea barbara (Osmundaceae) and the monotypic Indian genus Brainea
(Polypodiaceae), form erect stems several feet in height; but these differ in
appearance from the Palm-like type of the Cyatheaceous tree ferns. On the
other hand, the thin, almost transparent, leaf of Hymenophyllum
tunbridgense and other filmy ferns is a character shared by several species
It is noteworthy that while certain vegetative features may in some cases
be cited as family-characters, such features are not usually of much value
from a taxonomic point of view. While the typical tree ferns are practically
all members of the Cyatheaceae, a few members of other families, e.g.
Todea barbara (Osmundaceae) and the monotypic Indian genus Brainea
(Polypodiaceae), form erect stems several feet in height; but these differ in
appearance from the Palm-like type of the Cyatheaceous tree ferns. On the
other hand, the thin, almost transparent, leaf of Hymenophyllum
tunbridgense and other filmy ferns is a character shared by several species
Page 337
of Todea, Asplenium resectum, and Danaea trichomanoides (Marattiaceae);
the filmy habit is essentially a biological adaptation.
The form of frond represented by certain species of Gleichenia,
characterised by a regular dichotomy of the axis and by the occurrence of
arrested buds, is on the whole a trustworthy character, though Davallia
aculeata (bearing spines on its rachis) (fig. 232) and Matonia sarmentosa
have fronds with a similar mode of branching and also bear arrested radius-
buds. A limited acquaintance with ferns as a whole often leads us to regard
a certain form of leaf as characteristic of a particular species, but more
extended enquiry usually exposes the fallacy of relying upon so capricious a
feature. The form of leaf illustrated by Trichomanes reniforme is met with
also in Gymnogramme reniformis and is fairly closely matched by the leaf
of Scolopendrium nigripes. The fronds of Matonia pectinata (figs. 227,
228) bear a close resemblance to those of Gleichenia Cunninghami,
Adiantum pedatum, and Cheiropteris palmatopedata[704].
The habit, leaf-form, and distribution of Ferns.
The full accounts of the structure and life-history of the common Male
Fern, given by Scott in his Structural Botany and by Bower in the Origin of
a Land Flora, render superfluous more than a brief reference to certain
general considerations in so far as they may facilitate a study of fossil types.
In size Ferns have a wide range: at the one extreme we have the filmy
fern Trichomanes Goebelianum[705], growing on tree stems in Venezuela,
with leaves 2·5 to 3 mm. in diameter, and at the other the tree ferns with tall
columnar stems reaching a height of 40 to 50 feet and terminating in a
crown of fronds with a spread of several feet. A common form of stem is
represented by the subterranean or creeping rhizome covered with ramental
scales or hairs: the remains of old leaves may persist as ragged stumps, or,
as in Oleandra, Polypodium vulgare and several other species, the leaf may
be cut off by the formation of an absciss-layer[706] leaving a clean-cut peg
projecting from the stem. As a rule the branches bear no relation to the
leaves and are often given off from the lower part of a petiole, but in a few
cases, e.g. in the Hymenophyllaceae, it is noteworthy that true axillary
branching is the rule[707]. In the typical tree-fern the surface resembles that
of a Cycadean trunk covered with persistent leaf-bases and a thick mass of
the filmy habit is essentially a biological adaptation.
The form of frond represented by certain species of Gleichenia,
characterised by a regular dichotomy of the axis and by the occurrence of
arrested buds, is on the whole a trustworthy character, though Davallia
aculeata (bearing spines on its rachis) (fig. 232) and Matonia sarmentosa
have fronds with a similar mode of branching and also bear arrested radius-
buds. A limited acquaintance with ferns as a whole often leads us to regard
a certain form of leaf as characteristic of a particular species, but more
extended enquiry usually exposes the fallacy of relying upon so capricious a
feature. The form of leaf illustrated by Trichomanes reniforme is met with
also in Gymnogramme reniformis and is fairly closely matched by the leaf
of Scolopendrium nigripes. The fronds of Matonia pectinata (figs. 227,
228) bear a close resemblance to those of Gleichenia Cunninghami,
Adiantum pedatum, and Cheiropteris palmatopedata[704].
The habit, leaf-form, and distribution of Ferns.
The full accounts of the structure and life-history of the common Male
Fern, given by Scott in his Structural Botany and by Bower in the Origin of
a Land Flora, render superfluous more than a brief reference to certain
general considerations in so far as they may facilitate a study of fossil types.
In size Ferns have a wide range: at the one extreme we have the filmy
fern Trichomanes Goebelianum[705], growing on tree stems in Venezuela,
with leaves 2·5 to 3 mm. in diameter, and at the other the tree ferns with tall
columnar stems reaching a height of 40 to 50 feet and terminating in a
crown of fronds with a spread of several feet. A common form of stem is
represented by the subterranean or creeping rhizome covered with ramental
scales or hairs: the remains of old leaves may persist as ragged stumps, or,
as in Oleandra, Polypodium vulgare and several other species, the leaf may
be cut off by the formation of an absciss-layer[706] leaving a clean-cut peg
projecting from the stem. As a rule the branches bear no relation to the
leaves and are often given off from the lower part of a petiole, but in a few
cases, e.g. in the Hymenophyllaceae, it is noteworthy that true axillary
branching is the rule[707]. In the typical tree-fern the surface resembles that
of a Cycadean trunk covered with persistent leaf-bases and a thick mass of
Page 338
roots. Among epiphytic ferns highly modified stems are occasionally met
with, as in the Malayan species Polypodium (Lecanopteris) carnosum and
P. sinuosum[708].
The leaves of ferns are among the most protean of all plant organs; as
Darwin wrote, “the variability of ferns passes all bounds[709].” The highly
compound tri- or quadripinnate leaves of such species as Pteris aquilina,
Davallia and other genera stand for the central type of fern frond; others
exhibit a well-marked dichotomy, e.g. Lygodium, Gleichenia, Matonia, etc.,
a habit in all probability associated with the older rather than with the more
modern products of fern evolution. Before attempting to determine
specifically fossil fern fronds, it is important to familiarise ourselves with
the range of variability among existing species and more especially in
leaves of the same plant. A striking example of heteromorphy is illustrated
in fig. 233. Reinecke[710] has figured a plant of Asplenium multilineatum in
which the segments of the compound fronds assume various forms. In
Teratophyllum aculeatum var. inermis Mett., a tropical climbing fern
believed by Karsten[711] to be identical with Acrostichum (Lomariopsis)
sorbifolium,—an identification which Goebel[712] questions,—the fronds
which stand free of the stem supporting the climber differ considerably
from the translucent and much more delicate filmy leaves pressed against
the supporting tree. From this fern alone Fée is said to have created 17
distinct species. In this, as in many other cases, differences in leaf-form are
the expression of a physiological division of labour connected with an
epiphytic existence. Some tropical species of Polypodium (sect. Drynaria),
e.g. P. quercifolium (fig. 234 and fig. 231, D), produce two distinct types of
leaf, the large green fronds, concerned with the assimilation of carbon and
spore-production, being in sharp contrast to the small slightly lobed brown
leaves which act as stiff brackets (fig. 234, M) for collecting humus from
which the roots absorb raw material. Similarly in Platycerium the orbicular
mantle-leaves differ widely from the long pendulous or erect fronds
fashioned like the spreading antlers of an elk. In Hemitelia capensis, a
South African Cyatheaceous species, the basal pinnae assume the form of
finely divided leaves identified by earlier collectors as those of a parasitic
Trichomanes (fig. 235). In a letter written by W. H. Harvey in 1837
accompanying the specimen shown in fig. 235, he says, “Apropos of
Hemitelia, be it known abroad that supposed parasitical Trichomanes ... is
with, as in the Malayan species Polypodium (Lecanopteris) carnosum and
P. sinuosum[708].
The leaves of ferns are among the most protean of all plant organs; as
Darwin wrote, “the variability of ferns passes all bounds[709].” The highly
compound tri- or quadripinnate leaves of such species as Pteris aquilina,
Davallia and other genera stand for the central type of fern frond; others
exhibit a well-marked dichotomy, e.g. Lygodium, Gleichenia, Matonia, etc.,
a habit in all probability associated with the older rather than with the more
modern products of fern evolution. Before attempting to determine
specifically fossil fern fronds, it is important to familiarise ourselves with
the range of variability among existing species and more especially in
leaves of the same plant. A striking example of heteromorphy is illustrated
in fig. 233. Reinecke[710] has figured a plant of Asplenium multilineatum in
which the segments of the compound fronds assume various forms. In
Teratophyllum aculeatum var. inermis Mett., a tropical climbing fern
believed by Karsten[711] to be identical with Acrostichum (Lomariopsis)
sorbifolium,—an identification which Goebel[712] questions,—the fronds
which stand free of the stem supporting the climber differ considerably
from the translucent and much more delicate filmy leaves pressed against
the supporting tree. From this fern alone Fée is said to have created 17
distinct species. In this, as in many other cases, differences in leaf-form are
the expression of a physiological division of labour connected with an
epiphytic existence. Some tropical species of Polypodium (sect. Drynaria),
e.g. P. quercifolium (fig. 234 and fig. 231, D), produce two distinct types of
leaf, the large green fronds, concerned with the assimilation of carbon and
spore-production, being in sharp contrast to the small slightly lobed brown
leaves which act as stiff brackets (fig. 234, M) for collecting humus from
which the roots absorb raw material. Similarly in Platycerium the orbicular
mantle-leaves differ widely from the long pendulous or erect fronds
fashioned like the spreading antlers of an elk. In Hemitelia capensis, a
South African Cyatheaceous species, the basal pinnae assume the form of
finely divided leaves identified by earlier collectors as those of a parasitic
Trichomanes (fig. 235). In a letter written by W. H. Harvey in 1837
accompanying the specimen shown in fig. 235, he says, “Apropos of
Hemitelia, be it known abroad that supposed parasitical Trichomanes ... is
Page 339
not a parasite, but a part of the frond of Hemitelia.” The delicate reduced
pinnae remain on the stem and form a cluster at the base of the fronds[713].
Fig. 233. Polypodium Billardieri Br. (¼ nat. size.) Middle Island, New Zealand. From
specimens in the Cambridge Herbarium.
pinnae remain on the stem and form a cluster at the base of the fronds[713].
Fig. 233. Polypodium Billardieri Br. (¼ nat. size.) Middle Island, New Zealand. From
specimens in the Cambridge Herbarium.
Page 340
Fig. 234. Polypodium quercifolium. (Much reduced: M, Mantle-leaves.)
In many species the sporophylls are distinguished from the sterile fronds
by segments with little or no chlorophyllous tissue, as in Onoclea
struthiopteris[714] in which, each year, the plant produces a funnel-shaped
group of sterile leaves followed later in the season by a cluster of
sporophylls; or, as in many other genera, the fertile leaves are distinguished
also by longer petioles and thus serve as more efficient agents of spore-
dissemination. In Ceratopteris the narrow segments of the taller fertile
leaves are in striking contrast to the broader pinnules of the submerged
foliage leaves. Leaf-form is in many cases obviously the expression of
environment; the xerophilous fern Jamesonia[715] from the treeless paramos
of the Andes[716] is characterised by its minute leaflets with strong revolute
margins and a thick felt of hairs on the lower surface; in others, xerophilous
features take the form of a covering of overlapping scales (Ceterach), or a
development of water-tissue as in the fleshy leaves of the Himalayan fern
Drymoglossum carnosum. In the Bracken fern Boodle[717] has shown how
the fronds may be classed as shade and sun leaves; the former are spreading
In many species the sporophylls are distinguished from the sterile fronds
by segments with little or no chlorophyllous tissue, as in Onoclea
struthiopteris[714] in which, each year, the plant produces a funnel-shaped
group of sterile leaves followed later in the season by a cluster of
sporophylls; or, as in many other genera, the fertile leaves are distinguished
also by longer petioles and thus serve as more efficient agents of spore-
dissemination. In Ceratopteris the narrow segments of the taller fertile
leaves are in striking contrast to the broader pinnules of the submerged
foliage leaves. Leaf-form is in many cases obviously the expression of
environment; the xerophilous fern Jamesonia[715] from the treeless paramos
of the Andes[716] is characterised by its minute leaflets with strong revolute
margins and a thick felt of hairs on the lower surface; in others, xerophilous
features take the form of a covering of overlapping scales (Ceterach), or a
development of water-tissue as in the fleshy leaves of the Himalayan fern
Drymoglossum carnosum. In the Bracken fern Boodle[717] has shown how
the fronds may be classed as shade and sun leaves; the former are spreading
Page 341
and softer, while the latter are relatively smaller and of harder texture (fig.
236, a and b). Even in one leaf six feet high, growing through a dense bush
of gorse and bramble, the lower part was found to have the features of a
shade leaf, while the uppermost exposed pinnae were xerophilous.
Fig. 235. Hemitelia capensis R. Brown. Nat. size. a, Pinna of normal frond.
[From a specimen in the British Museum. M.S.]
236, a and b). Even in one leaf six feet high, growing through a dense bush
of gorse and bramble, the lower part was found to have the features of a
shade leaf, while the uppermost exposed pinnae were xerophilous.
Fig. 235. Hemitelia capensis R. Brown. Nat. size. a, Pinna of normal frond.
[From a specimen in the British Museum. M.S.]
Page 342
Fig. 236a. Pteris aquilina.
Part of leaf from greenhouse. (¼ nat. size.) After Boodle.
PTERIS
The resemblance between some of the filmy Hymenophyllaceae and
thalloid Liverworts[718] is worthy of mention as one of the many possible
pitfalls to be avoided by the palaeobotanical student. The long linear fronds
of such genera as Vittaria and Monogramme might well be identified in a
fossil state as the leaves of a grass-like Monocotyledon, or compared with
the foliage of Isoetes or Pilularia. The resemblance of some fern leaves
with reticulate venation to those of Dicotyledons has led astray experienced
Part of leaf from greenhouse. (¼ nat. size.) After Boodle.
PTERIS
The resemblance between some of the filmy Hymenophyllaceae and
thalloid Liverworts[718] is worthy of mention as one of the many possible
pitfalls to be avoided by the palaeobotanical student. The long linear fronds
of such genera as Vittaria and Monogramme might well be identified in a
fossil state as the leaves of a grass-like Monocotyledon, or compared with
the foliage of Isoetes or Pilularia. The resemblance of some fern leaves
with reticulate venation to those of Dicotyledons has led astray experienced
Page 343
palaeobotanists; it is not only the anastomosing venation in the leaves of
several ferns that simulates dicotyledonous foliage, but the compound
leaves of many dicotyledons, e.g. Paullinia thalictrifolia (Sapindaceae) and
species of Umbelliferae, may easily be mistaken for fronds of ferns.
Fig. 236b. Pteris aquilina.
Leaf from the same plant grown out of doors. (¼ nat. size.)
After Boodle.
RECENT FERNS
The dichotomously lobed lamina of some Schizaeas, e.g. S. dichotoma
and S. elegans (fig. 222), bears a close resemblance to the leaves of Baiera
several ferns that simulates dicotyledonous foliage, but the compound
leaves of many dicotyledons, e.g. Paullinia thalictrifolia (Sapindaceae) and
species of Umbelliferae, may easily be mistaken for fronds of ferns.
Fig. 236b. Pteris aquilina.
Leaf from the same plant grown out of doors. (¼ nat. size.)
After Boodle.
RECENT FERNS
The dichotomously lobed lamina of some Schizaeas, e.g. S. dichotoma
and S. elegans (fig. 222), bears a close resemblance to the leaves of Baiera
Page 344
or Ginkgo[719]. The original description by Kunze[720] of the South African
Cycad Stangeria paradoxa as a Polypodiaceous fern illustrates the
difficulty, or indeed impossibility, of distinguishing between a sterile simply
pinnate fern frond and the foliage of some Cycads. The deeply divided
segments of Cycas Micholitzii[721] simulate the dichotomously branched
pinnae of Lygodium dichotomum, and the leaves of Aneimia rotundifolia
(fig. 223) and other species are almost identical in form with the Jurassic
species Otozamites Beani, a member of the Cycadophyta.
There are certain facts in regard to the geographical distribution of ferns
to which attention should be directed. Mr Baker in his paper on fern
distribution writes: “With the precision of an hygrometer, an increase in the
fern-vegetation marks the wooded humid regions[722].” If in a collection of
fossil plants we find a preponderance of ferns we are tempted to assume the
existence of such conditions as are favourable to the luxuriant development
of ferns at the present day. On the other hand, we must bear in mind the
wonderful plasticity of many recent species and the fact that xerophilous
ferns are by no means unknown in present-day floras.
Ferns are admirably adapted to rapid dispersal over comparatively wide
areas. Bower[723] estimates that in one season a Male Fern may produce
about 5,000,000 spores: with this enormous spore-output are coupled a
thoroughly efficient mechanism for scattering the germs and an unusual
facility for wind-dispersal. When Treub[724] visited the devastated and
sterilised wreck of the Island of Krakatau in 1886, three years after the
volcanic outburst, he found that twelve ferns had already established
themselves; the spores had probably been carried by the wind at least 25 to
30 miles. It is not surprising, therefore, to find that many ferns have an
almost world-wide distribution; and, it may be added, in view of their
efficient means of dispersal, wide range by no means implies great
antiquity. Prof. Campbell[725] has recently called attention to the significance
of the wide distribution of Hepaticae in its bearing on their antiquity; the
spores are incapable of retaining vitality for more than a short period, and it
is argued that a world-wide distribution can have been acquired only after
an enormous lapse of time. If we apply this reasoning to the Osmundaceae
among ferns, it may be legitimate to assume that their short-lived green
spores render them much less efficient colonisers than the great majority of
ferns; if this is granted, the wide distribution of Osmundaceous ferns in the
Cycad Stangeria paradoxa as a Polypodiaceous fern illustrates the
difficulty, or indeed impossibility, of distinguishing between a sterile simply
pinnate fern frond and the foliage of some Cycads. The deeply divided
segments of Cycas Micholitzii[721] simulate the dichotomously branched
pinnae of Lygodium dichotomum, and the leaves of Aneimia rotundifolia
(fig. 223) and other species are almost identical in form with the Jurassic
species Otozamites Beani, a member of the Cycadophyta.
There are certain facts in regard to the geographical distribution of ferns
to which attention should be directed. Mr Baker in his paper on fern
distribution writes: “With the precision of an hygrometer, an increase in the
fern-vegetation marks the wooded humid regions[722].” If in a collection of
fossil plants we find a preponderance of ferns we are tempted to assume the
existence of such conditions as are favourable to the luxuriant development
of ferns at the present day. On the other hand, we must bear in mind the
wonderful plasticity of many recent species and the fact that xerophilous
ferns are by no means unknown in present-day floras.
Ferns are admirably adapted to rapid dispersal over comparatively wide
areas. Bower[723] estimates that in one season a Male Fern may produce
about 5,000,000 spores: with this enormous spore-output are coupled a
thoroughly efficient mechanism for scattering the germs and an unusual
facility for wind-dispersal. When Treub[724] visited the devastated and
sterilised wreck of the Island of Krakatau in 1886, three years after the
volcanic outburst, he found that twelve ferns had already established
themselves; the spores had probably been carried by the wind at least 25 to
30 miles. It is not surprising, therefore, to find that many ferns have an
almost world-wide distribution; and, it may be added, in view of their
efficient means of dispersal, wide range by no means implies great
antiquity. Prof. Campbell[725] has recently called attention to the significance
of the wide distribution of Hepaticae in its bearing on their antiquity; the
spores are incapable of retaining vitality for more than a short period, and it
is argued that a world-wide distribution can have been acquired only after
an enormous lapse of time. If we apply this reasoning to the Osmundaceae
among ferns, it may be legitimate to assume that their short-lived green
spores render them much less efficient colonisers than the great majority of
ferns; if this is granted, the wide distribution of Osmundaceous ferns in the
Page 345
Mesozoic era carries their history back to a still more remote past, a
conclusion which receives support from the records of the rocks.
The Bracken fern which we regard as characteristically British is a
cosmopolitan type; it was found by Treub among the pioneers of the New
Flora of Krakatau; in British Central Africa, it greets one at every turn “like
a messenger from the homeland[726]”; it grows on the Swiss Alps, on the
mountains of Abyssinia, in Tasmania, and on the slopes of the Himalayas.
The two genera Matonia (fig. 228) and Dipteris, which grow side by side
on Mount Ophir in the Malay Peninsula, are examples of restricted
geographical range and carry us back to the Jurassic period when closely
allied types flourished abundantly in northern latitudes. Similarly
Thyrsopteris elegans, confined to Juan Fernandez, exhibits a remarkable
likeness to Jurassic species from England and the Arctic regions.
The proportion of ferns to flowering plants in recent floras is a question
of some interest from a palaeobotanical point of view; but we must bear in
mind the fact that the evolution of angiosperms, effected at a late stage in
the history of the earth, seriously disturbed the balance of power among
competitors for earth and air. The abundance of ferns in a particular region
is, however, an unsafe guide to geographical or climatic conditions. Many
ferns are essentially social plants; the wide stretches of moorland carpeted
with Pteris aquilina afford an example of the monopolisation of the soil by
a single species. In Sikkim Sir Joseph Hooker speaks of extensive groves of
tree ferns, and in the wet regions of the Amazon, Bates[727] describes the
whole forest glade as forming a “vast fernery.” In a valley in Tahiti
Alsophila tahitiensis is said to form “a sort of forest almost to the exclusion
of other ferns[728].” In the abundance of Glossopteris (figs. 334, etc.) fronds
spread over wide areas of Permo-Carboniferous rocks in S. Africa,
Australia, and India, we have a striking instance of a similar social habit in
an extinct fern or at least fern-like plant.
Acrostichum aureum, with pinnate fronds several feet long, is an example
of a recent fern covering immense tracts, but this species[729] is more
especially interesting as a member of the Filicineae characteristic of
brackish marshes and the banks of tropical rivers in company with
Mangrove plants and the “Stemless Palm” Nipa. This species exhibits the
anatomical characters of a water-plant and affords an interesting parallel
conclusion which receives support from the records of the rocks.
The Bracken fern which we regard as characteristically British is a
cosmopolitan type; it was found by Treub among the pioneers of the New
Flora of Krakatau; in British Central Africa, it greets one at every turn “like
a messenger from the homeland[726]”; it grows on the Swiss Alps, on the
mountains of Abyssinia, in Tasmania, and on the slopes of the Himalayas.
The two genera Matonia (fig. 228) and Dipteris, which grow side by side
on Mount Ophir in the Malay Peninsula, are examples of restricted
geographical range and carry us back to the Jurassic period when closely
allied types flourished abundantly in northern latitudes. Similarly
Thyrsopteris elegans, confined to Juan Fernandez, exhibits a remarkable
likeness to Jurassic species from England and the Arctic regions.
The proportion of ferns to flowering plants in recent floras is a question
of some interest from a palaeobotanical point of view; but we must bear in
mind the fact that the evolution of angiosperms, effected at a late stage in
the history of the earth, seriously disturbed the balance of power among
competitors for earth and air. The abundance of ferns in a particular region
is, however, an unsafe guide to geographical or climatic conditions. Many
ferns are essentially social plants; the wide stretches of moorland carpeted
with Pteris aquilina afford an example of the monopolisation of the soil by
a single species. In Sikkim Sir Joseph Hooker speaks of extensive groves of
tree ferns, and in the wet regions of the Amazon, Bates[727] describes the
whole forest glade as forming a “vast fernery.” In a valley in Tahiti
Alsophila tahitiensis is said to form “a sort of forest almost to the exclusion
of other ferns[728].” In the abundance of Glossopteris (figs. 334, etc.) fronds
spread over wide areas of Permo-Carboniferous rocks in S. Africa,
Australia, and India, we have a striking instance of a similar social habit in
an extinct fern or at least fern-like plant.
Acrostichum aureum, with pinnate fronds several feet long, is an example
of a recent fern covering immense tracts, but this species[729] is more
especially interesting as a member of the Filicineae characteristic of
brackish marshes and the banks of tropical rivers in company with
Mangrove plants and the “Stemless Palm” Nipa. This species exhibits the
anatomical characters of a water-plant and affords an interesting parallel
Page 346
with some Palaeozoic ferns (species of Psaronius) which probably grew
under similar conditions.
The Anatomy of Ferns.
The text-book accounts of fern-anatomy convey a very inadequate idea
of the architectural characters displayed by the vascular systems of recent
genera. When we are concerned with the study of extinct plants it is
essential to be familiar not only with the commoner recent types, but
particularly with exceptional or aberrant types. The vascular system of
many ferns consists of strands of xylem composed of scalariform tracheae
associated with a larger or smaller amount of parenchyma, surrounded
either wholly or in part (that is concentric or bicollateral) by phloem:
beyond this is a pericycle, one layer or frequently several layers in breadth,
limited externally by an endodermis, which can usually be readily
recognised. The vascular strands are embedded in the ground-tissue of the
stem consisting of thin-walled parenchyma and, in most ferns, a
considerable quantity of hard and lignified mechanical tissue. The narrow
protoxylem elements are usually characterised by a spiral form of
thickening, but in slow-growing stems the first-formed elements are
frequently of the scalariform type.
A study of the anatomy of recent ferns both in the adult state and in
successive stages of development from the embryo has on the whole
revealed “a striking parallelism[730]” between vascular and sporangial
characters in leptosporangiate ferns. For a masterly treatment of our
knowledge of fern anatomy from a phylogenetic point of view reference
should be made to Mr Tansley’s recently published lectures: within the
limits of this volume all that is possible is a brief outline of the main types
of vascular structure illustrated by recent genera.
under similar conditions.
The Anatomy of Ferns.
The text-book accounts of fern-anatomy convey a very inadequate idea
of the architectural characters displayed by the vascular systems of recent
genera. When we are concerned with the study of extinct plants it is
essential to be familiar not only with the commoner recent types, but
particularly with exceptional or aberrant types. The vascular system of
many ferns consists of strands of xylem composed of scalariform tracheae
associated with a larger or smaller amount of parenchyma, surrounded
either wholly or in part (that is concentric or bicollateral) by phloem:
beyond this is a pericycle, one layer or frequently several layers in breadth,
limited externally by an endodermis, which can usually be readily
recognised. The vascular strands are embedded in the ground-tissue of the
stem consisting of thin-walled parenchyma and, in most ferns, a
considerable quantity of hard and lignified mechanical tissue. The narrow
protoxylem elements are usually characterised by a spiral form of
thickening, but in slow-growing stems the first-formed elements are
frequently of the scalariform type.
A study of the anatomy of recent ferns both in the adult state and in
successive stages of development from the embryo has on the whole
revealed “a striking parallelism[730]” between vascular and sporangial
characters in leptosporangiate ferns. For a masterly treatment of our
knowledge of fern anatomy from a phylogenetic point of view reference
should be made to Mr Tansley’s recently published lectures: within the
limits of this volume all that is possible is a brief outline of the main types
of vascular structure illustrated by recent genera.
Page 347
Fig. 237.
A. Matonia pectinata (petiole).
B. M. pectinata (stem).
C. Gleichenia dicarpa (stem): p, petiole; pp, protophloem; position of protoxylem
indicated by black dots.
D. Matonidium.
E. Trichomanes reniforme: pp, protophloem.
(C, E, after Boodle; D, after Bommer.)
To Prof. Jeffrey[731] we owe the term protostele which he applied to a type
of stele consisting of a central core of xylem surrounded by phloem,
pericycle, and endodermis. While admitting that steles of this type may
sometimes be the result of the modification of less simple forms, we may
confidently regard the protostele as representing the most primitive form of
vascular system. The genus Lygodium affords an example of a protostelic
fern; a solid column of xylem tracheae and parenchyma is completely
encircled by a cylinder of phloem succeeded by a multi-layered pericycle
and an endodermis of a single layer of cells. In this genus the stele is
characterised by marginal groups of protoxylem; it is exarch. An almost
identical type is represented by species of Gleichenia, but here the stele is
mesarch, the protoxylem being slightly internal (fig. 237, C). Trichomanes
scandens (fig. 238) has an exarch protostele like that of Lygodium; but, as
Boodle[732] has suggested, the protostelic form in this case is probably the
A. Matonia pectinata (petiole).
B. M. pectinata (stem).
C. Gleichenia dicarpa (stem): p, petiole; pp, protophloem; position of protoxylem
indicated by black dots.
D. Matonidium.
E. Trichomanes reniforme: pp, protophloem.
(C, E, after Boodle; D, after Bommer.)
To Prof. Jeffrey[731] we owe the term protostele which he applied to a type
of stele consisting of a central core of xylem surrounded by phloem,
pericycle, and endodermis. While admitting that steles of this type may
sometimes be the result of the modification of less simple forms, we may
confidently regard the protostele as representing the most primitive form of
vascular system. The genus Lygodium affords an example of a protostelic
fern; a solid column of xylem tracheae and parenchyma is completely
encircled by a cylinder of phloem succeeded by a multi-layered pericycle
and an endodermis of a single layer of cells. In this genus the stele is
characterised by marginal groups of protoxylem; it is exarch. An almost
identical type is represented by species of Gleichenia, but here the stele is
mesarch, the protoxylem being slightly internal (fig. 237, C). Trichomanes
scandens (fig. 238) has an exarch protostele like that of Lygodium; but, as
Boodle[732] has suggested, the protostelic form in this case is probably the
Page 348
result of modification of a collateral form of stele such as occurs in
Trichomanes reniforme (fig. 237, E). A second type of stele has been
described in species of Lindsaya[733] in which the xylem includes a small
group of phloem near the dorsal surface. This Lindsaya type is often passed
through in the development of “seedling” ferns and may be regarded as a
stage in a series leading to another well-marked type, the solenostele. The
solenostele[734], a hollow cylinder of xylem lined within and without by
phloem, pericycle, and endodermis, occurs in several genera belonging to
different families, e.g. Dipteris, species of Pteris, species of Lindsaya,
Polypodium, Jamesonia, Loxsoma, Gleichenia and other genera. In a
smaller number of ferns the stele consists of what may be called a
medullated protostele similar to the common form of stele in
Lepidodendron: this type is found in species of Schizaea and in Platyzoma
(fig. 239). It is important to notice that in the solenostele and as a rule in the
medullated protostele when a leaf-trace passes out from the rhizome stele
the vascular cylinder is interrupted by the formation of a foliar gap
(Platyzoma[735], fig. 239, is an exception). This fact has been emphasized by
Jeffrey[736] who draws a distinction between the Lycopodiaceous type of
stele, which is not broken by the exit of leaf-traces, and the fern stele in
which foliar gaps are produced: the former he speaks of as the
cladosiphonic type (Lycopsida) and the latter as the phyllosiphonic
(Pteropsida).
Trichomanes reniforme (fig. 237, E). A second type of stele has been
described in species of Lindsaya[733] in which the xylem includes a small
group of phloem near the dorsal surface. This Lindsaya type is often passed
through in the development of “seedling” ferns and may be regarded as a
stage in a series leading to another well-marked type, the solenostele. The
solenostele[734], a hollow cylinder of xylem lined within and without by
phloem, pericycle, and endodermis, occurs in several genera belonging to
different families, e.g. Dipteris, species of Pteris, species of Lindsaya,
Polypodium, Jamesonia, Loxsoma, Gleichenia and other genera. In a
smaller number of ferns the stele consists of what may be called a
medullated protostele similar to the common form of stele in
Lepidodendron: this type is found in species of Schizaea and in Platyzoma
(fig. 239). It is important to notice that in the solenostele and as a rule in the
medullated protostele when a leaf-trace passes out from the rhizome stele
the vascular cylinder is interrupted by the formation of a foliar gap
(Platyzoma[735], fig. 239, is an exception). This fact has been emphasized by
Jeffrey[736] who draws a distinction between the Lycopodiaceous type of
stele, which is not broken by the exit of leaf-traces, and the fern stele in
which foliar gaps are produced: the former he speaks of as the
cladosiphonic type (Lycopsida) and the latter as the phyllosiphonic
(Pteropsida).
Page 349
Fig. 238. Stele of Trichomanes scandens: px, protoxylem; s, endodermis.
From Tansley, after Boodle.
Fig. 239. Platyzoma microphylla. l.t., leaf-trace; i.e., internal endodermis. (After Tansley;
modified from Boodle.)
The transition to a hollow cylinder of xylem from a protostele may be
described as the result of the replacement of some of the axial conducting
From Tansley, after Boodle.
Fig. 239. Platyzoma microphylla. l.t., leaf-trace; i.e., internal endodermis. (After Tansley;
modified from Boodle.)
The transition to a hollow cylinder of xylem from a protostele may be
described as the result of the replacement of some of the axial conducting
Page 350
tracheae by parenchyma or other non-vascular tissue consequent on an
increase in diameter of the whole stele and the concentration of the true
conducting elements towards the periphery[737].
The occurrence of the internal cylinder of phloem, pericycle, and
endodermis in a solenostele is rendered intelligible by a study of fern
seedlings and by a comparative examination of transitional types
connecting protosteles and solenosteles through medullated protosteles and
steles of the Lindsaya type. A further stage in stelar evolution is illustrated
by what is termed the dictyostele, the arrangement of vascular tissue
characteristic of Nephrodium Filix-mas, Cyathea (fig. 240), Polypodium
vulgare and many other common ferns.
Fig. 240. Cyathea Imrayana. (From Tansley after de Bary.) (Sclerenchyma represented by
black bands.)
If a solenostele is interrupted by leaf-gaps at intervals sufficiently close
to cause overlapping, a transverse section at any part of the stele will show
apparently separate curved bands of concentrically arranged xylem and
phloem, which on dissection are seen to represent parts of a continuous
lattice-work or a cylinder with the wall pierced by large meshes. The
manner of evolution of the dictyostele has been ably dealt with by Gwynne-
Vaughan[738] and other authors. In a few ferns, e.g. Matonia pectinata[739], a
increase in diameter of the whole stele and the concentration of the true
conducting elements towards the periphery[737].
The occurrence of the internal cylinder of phloem, pericycle, and
endodermis in a solenostele is rendered intelligible by a study of fern
seedlings and by a comparative examination of transitional types
connecting protosteles and solenosteles through medullated protosteles and
steles of the Lindsaya type. A further stage in stelar evolution is illustrated
by what is termed the dictyostele, the arrangement of vascular tissue
characteristic of Nephrodium Filix-mas, Cyathea (fig. 240), Polypodium
vulgare and many other common ferns.
Fig. 240. Cyathea Imrayana. (From Tansley after de Bary.) (Sclerenchyma represented by
black bands.)
If a solenostele is interrupted by leaf-gaps at intervals sufficiently close
to cause overlapping, a transverse section at any part of the stele will show
apparently separate curved bands of concentrically arranged xylem and
phloem, which on dissection are seen to represent parts of a continuous
lattice-work or a cylinder with the wall pierced by large meshes. The
manner of evolution of the dictyostele has been ably dealt with by Gwynne-
Vaughan[738] and other authors. In a few ferns, e.g. Matonia pectinata[739], a
Page 351
transverse section of the stem (fig. 237, B) reveals the presence of two or in
some cases three concentric solenosteles with a solid protostele in the
centre: this polycylic type may be regarded as the expression of the fact that
in response to the need for an adequate water-supply to the large fronds,
ferns have increased the conducting channels by a method other than by the
mere increase of the diameter of a single stele. Fig. 237, A, shows the
vascular tissue of a petiole of Matonia in transverse section.
The two genera of Osmundaceae, Todea and Osmunda, are peculiar
among recent ferns in having a vascular cylinder composed of separate
strands of xylem varying considerably in shape and size, from U-shaped
strands with the concavity facing the centre of the stem and with the
protoxylem in the hollow of the U, to oval or more or less circular strands
with a mesarch protoxylem or without any protoxylem elements (fig. 221,
A, B). These different forms are the expression of the change in contour or
in structure which the parts of the lattice-work undergo at different levels in
the stem[740]. Beyond this ring of xylem bundles is a continuous sheath of
phloem of characteristic structure. A transverse section of a stem of
Osmunda regalis may show 15 or more xylem strands; in O. Claytoniana
there may be as many as 40. In Todea barbara (fig. 221, B) the leaf-gaps
are shorter, and in consequence of the less amount of overlapping the xylem
cylinder becomes an almost continuous tube. The recent researches of
Kidston and Gwynne-Vaughan[741] have resulted in the discovery of fossil
Osmundaceous stems with a complete xylem ring, the stele being of the
medullated protostele type; in another extinct member of the family the
stele consists of a solid xylem core. The Osmundaceous type of stele is
complicated in O. cinnamomea (fig. 221, A) by the occurrence of local
internal phloem and by an internal endodermis, a feature which leads
Jeffrey to what I believe to be an incorrect conclusion that the vascular
arrangement found in Osmunda regalis has been evolved by reduction from
a stele in which the xylem was enclosed within and without by phloem.
New facts recently brought to light enable us to derive the ordinary
Osmundaceous type from the protostele and solenostele. It is worthy of
remark that the Osmundaceae occupy a somewhat isolated position among
recent ferns; their anatomy represents a special type, their sporangia differ
in several respects from those of other leptosporangiate ferns and in some
features Osmunda and Todea agree with the Eusporangiate ferns. The
possession of such distinguishing characters as these suggests antiquity; and
some cases three concentric solenosteles with a solid protostele in the
centre: this polycylic type may be regarded as the expression of the fact that
in response to the need for an adequate water-supply to the large fronds,
ferns have increased the conducting channels by a method other than by the
mere increase of the diameter of a single stele. Fig. 237, A, shows the
vascular tissue of a petiole of Matonia in transverse section.
The two genera of Osmundaceae, Todea and Osmunda, are peculiar
among recent ferns in having a vascular cylinder composed of separate
strands of xylem varying considerably in shape and size, from U-shaped
strands with the concavity facing the centre of the stem and with the
protoxylem in the hollow of the U, to oval or more or less circular strands
with a mesarch protoxylem or without any protoxylem elements (fig. 221,
A, B). These different forms are the expression of the change in contour or
in structure which the parts of the lattice-work undergo at different levels in
the stem[740]. Beyond this ring of xylem bundles is a continuous sheath of
phloem of characteristic structure. A transverse section of a stem of
Osmunda regalis may show 15 or more xylem strands; in O. Claytoniana
there may be as many as 40. In Todea barbara (fig. 221, B) the leaf-gaps
are shorter, and in consequence of the less amount of overlapping the xylem
cylinder becomes an almost continuous tube. The recent researches of
Kidston and Gwynne-Vaughan[741] have resulted in the discovery of fossil
Osmundaceous stems with a complete xylem ring, the stele being of the
medullated protostele type; in another extinct member of the family the
stele consists of a solid xylem core. The Osmundaceous type of stele is
complicated in O. cinnamomea (fig. 221, A) by the occurrence of local
internal phloem and by an internal endodermis, a feature which leads
Jeffrey to what I believe to be an incorrect conclusion that the vascular
arrangement found in Osmunda regalis has been evolved by reduction from
a stele in which the xylem was enclosed within and without by phloem.
New facts recently brought to light enable us to derive the ordinary
Osmundaceous type from the protostele and solenostele. It is worthy of
remark that the Osmundaceae occupy a somewhat isolated position among
recent ferns; their anatomy represents a special type, their sporangia differ
in several respects from those of other leptosporangiate ferns and in some
features Osmunda and Todea agree with the Eusporangiate ferns. The
possession of such distinguishing characters as these suggests antiquity; and
Page 352
the facts of palaeobotany, as also the present geographical range of the
family, confirm the correctness of this deduction.
Before leaving the stelar structure of leptosporangiate fern stems, a word
must be added in regard to a type of structure met with in the
Hymenophyllaceae. In this family Trichomanes reniforme (fig. 237, E) may
be regarded, as Boodle suggests, as the central type: the stele consists of a
ring of metaxylem tracheae, the dorsal portion having the form of a flat arch
and the ventral half that of a straight band. This flattened ring of xylem
encloses parenchymatous tissue containing scattered tracheae some of
which are protoxylem elements. In Trichomanes radicans the rhizome is
stouter than in T. reniforme and the stele consists of a greater number of
tracheae. The stele is cylindrical like that shown in fig. 238, but the centre is
occupied by two groups of protoxylem and associated parenchyma. In
Hymenophyllum tunbrigense the stele is of the subcollateral type; the
ventral plate of the xylem ring has disappeared leaving a single strand of
xylem with endarch protoxylem and completely surrounded by phloem.
Trichomanes muscoides possesses a still simpler stele consisting of a
slender xylem strand with phloem on one side only. Reference has already
been made to the occurrence in this family of the protostelic type. The
Hymenophyllaceae afford a striking illustration of the modification in
different directions of stelar structure connected with differences in habit,
and of the correlation of demand and supply as shown in the varying
amount of conducting tissue in the steles of different species.
The leaf-trace in a great number of ferns is characterised by its C-shaped
form[742] as seen in transverse section: this in some genera, e.g. Matonia (fig.
237, A), is complicated by the spiral infolding of the free edges of the C; in
other ferns (e.g. some Cyatheaceae) (fig. 278, C) the sides of the C are
incurved, while in some species the xylem is broken up into a large number
of separate strands.
An elaborate treatment of the leaf-traces of ferns was published a few
years ago by MM. Bertrand and Cornaille[743] in which the authors show
how the various systems of vascular tissue in the fronds of ferns maybe
derived from a common type. As Prof. Chodat[744] justly remarks this
important work has not received the attention it deserves, the neglect being
attributed to the strange notation which is adopted[745].
family, confirm the correctness of this deduction.
Before leaving the stelar structure of leptosporangiate fern stems, a word
must be added in regard to a type of structure met with in the
Hymenophyllaceae. In this family Trichomanes reniforme (fig. 237, E) may
be regarded, as Boodle suggests, as the central type: the stele consists of a
ring of metaxylem tracheae, the dorsal portion having the form of a flat arch
and the ventral half that of a straight band. This flattened ring of xylem
encloses parenchymatous tissue containing scattered tracheae some of
which are protoxylem elements. In Trichomanes radicans the rhizome is
stouter than in T. reniforme and the stele consists of a greater number of
tracheae. The stele is cylindrical like that shown in fig. 238, but the centre is
occupied by two groups of protoxylem and associated parenchyma. In
Hymenophyllum tunbrigense the stele is of the subcollateral type; the
ventral plate of the xylem ring has disappeared leaving a single strand of
xylem with endarch protoxylem and completely surrounded by phloem.
Trichomanes muscoides possesses a still simpler stele consisting of a
slender xylem strand with phloem on one side only. Reference has already
been made to the occurrence in this family of the protostelic type. The
Hymenophyllaceae afford a striking illustration of the modification in
different directions of stelar structure connected with differences in habit,
and of the correlation of demand and supply as shown in the varying
amount of conducting tissue in the steles of different species.
The leaf-trace in a great number of ferns is characterised by its C-shaped
form[742] as seen in transverse section: this in some genera, e.g. Matonia (fig.
237, A), is complicated by the spiral infolding of the free edges of the C; in
other ferns (e.g. some Cyatheaceae) (fig. 278, C) the sides of the C are
incurved, while in some species the xylem is broken up into a large number
of separate strands.
An elaborate treatment of the leaf-traces of ferns was published a few
years ago by MM. Bertrand and Cornaille[743] in which the authors show
how the various systems of vascular tissue in the fronds of ferns maybe
derived from a common type. As Prof. Chodat[744] justly remarks this
important work has not received the attention it deserves, the neglect being
attributed to the strange notation which is adopted[745].
Page 353
The roots of ferns are characterised by a uniformity of plan in marked
contrast to the wide range of structure met with in the stem and to a less
extent in the leaves. The xylem may consist of a plate of scalariform
tracheae with a protoxylem group at each end, or the stele may include six
or more alternating strands of xylem and phloem.
II. Marattiales (Eusporangiate isosporous Filicales).
The Marattiaceae, the single family of ferns included in the Marattiales,
comprise the genera Angiopteris, Archangiopteris, Marattia, Danaea, and
Kaulfussia, which are for the most part tropical in distribution. These
genera are characterised by eusporangiate sori or synangia, the presence of
stipules at the base of the petioles, and by the complex arrangement of the
vascular tissue. In view of the fact that many fossil ferns show a close
resemblance to the recent Marattiaceae, the surviving genera are briefly
described. The prothallus is green and relatively large.
Angiopteris. This genus occurs in Polynesia, tropical Asia, and
Madagascar; it is characterised by a short and thick fleshy stem bearing
large bipinnate leaves which occasionally show a forking of the rachis[746], a
feature reminiscent of some Palaeozoic fern-like fronds. One of the large
plants of Angiopteris evecta in the Royal Gardens, Kew, bears leaves 12
feet in length with a stalk 6 inches in diameter at the base. The sessile or
shortly stalked and rather leathery linear or broadly lanceolate pinnules
have a prominent midrib and dichotomously branched lateral veins. The
surface of an old stem is covered with the thick stumps of petioles enclosed
by pairs of fleshy stipules (fig. 241, A) and bears numerous fleshy roots,
which hang free in the air or penetrate the soil. The young fronds (fig. 220,
A) exhibit very clearly the characteristic circinate vernation. The proximal
part of each primary pinna is characterised by a pulvinus-like swelling. The
sporangia, in short linear elliptical sori near the edge of the pinnules, consist
of free sporangia (fig. 242, A–D) provided with a peculiar type of
“annulus”[747], in the form of a narrow band of thicker-walled cells, which
extends as a broad strip on either side of the apex. An examination of
sections through the sporangia of Angiopteris in different planes[748]
illustrates the difficulty of determining the precise nature of the annulus in a
petrified sporangium which is seen only in one or two planes. Many of the
sporangia from the English Coal-Measures, compared by authors with those
contrast to the wide range of structure met with in the stem and to a less
extent in the leaves. The xylem may consist of a plate of scalariform
tracheae with a protoxylem group at each end, or the stele may include six
or more alternating strands of xylem and phloem.
II. Marattiales (Eusporangiate isosporous Filicales).
The Marattiaceae, the single family of ferns included in the Marattiales,
comprise the genera Angiopteris, Archangiopteris, Marattia, Danaea, and
Kaulfussia, which are for the most part tropical in distribution. These
genera are characterised by eusporangiate sori or synangia, the presence of
stipules at the base of the petioles, and by the complex arrangement of the
vascular tissue. In view of the fact that many fossil ferns show a close
resemblance to the recent Marattiaceae, the surviving genera are briefly
described. The prothallus is green and relatively large.
Angiopteris. This genus occurs in Polynesia, tropical Asia, and
Madagascar; it is characterised by a short and thick fleshy stem bearing
large bipinnate leaves which occasionally show a forking of the rachis[746], a
feature reminiscent of some Palaeozoic fern-like fronds. One of the large
plants of Angiopteris evecta in the Royal Gardens, Kew, bears leaves 12
feet in length with a stalk 6 inches in diameter at the base. The sessile or
shortly stalked and rather leathery linear or broadly lanceolate pinnules
have a prominent midrib and dichotomously branched lateral veins. The
surface of an old stem is covered with the thick stumps of petioles enclosed
by pairs of fleshy stipules (fig. 241, A) and bears numerous fleshy roots,
which hang free in the air or penetrate the soil. The young fronds (fig. 220,
A) exhibit very clearly the characteristic circinate vernation. The proximal
part of each primary pinna is characterised by a pulvinus-like swelling. The
sporangia, in short linear elliptical sori near the edge of the pinnules, consist
of free sporangia (fig. 242, A–D) provided with a peculiar type of
“annulus”[747], in the form of a narrow band of thicker-walled cells, which
extends as a broad strip on either side of the apex. An examination of
sections through the sporangia of Angiopteris in different planes[748]
illustrates the difficulty of determining the precise nature of the annulus in a
petrified sporangium which is seen only in one or two planes. Many of the
sporangia from the English Coal-Measures, compared by authors with those
Page 354
of Leptosporangiate ferns, are in all probability referable to the
Marattiaceous type.
Fig. 241.
A. Angiopteris evecta. (Considerably reduced.)
B. Marattia fraxinea. Stipule. M.S.
The vascular system[749] of the stem constitutes a highly complex
dictyostelic or polycylic type which may consist of as many as nine
concentric series of strands of xylem surrounded by phloem, with large
sieve-tubes and a pericycle which abuts on the parenchymatous ground-
tissue without any definite endodermal layer. A peculiarity in the vascular
strands is that the first-formed elements of the phloem lie close to the edge
of the xylem, the metaphloem being therefore centrifugal in its
development. The ground-tissue is devoid of mechanical tissue and is
penetrated by roots, a few of which arise from the outer vascular strands
while others force their way to the surface from the more internal
dictyosteles. Leaf-traces, consisting of several strands, are given off from
the outermost cylinder and a segment of the second dictyostele moves out
to fill the gap formed in the outermost network, while the gap in the second
cylinder receives compensating strands from the third. A few layers below
the surface of the petiole there is a ring of thick-walled elements (s, fig.
243), and in both petiole and stem numerous mucilage ducts and tannin-
sacs occur in the ground-tissue. It has been shown by Farmer and Hill[750]
that in some of the vascular strands in an Angiopteris stem a few secondary
tracheae are added to the primary xylem by the activity of the adjacent
parenchyma. The vascular bundles in the petiole form more or less regular
Marattiaceous type.
Fig. 241.
A. Angiopteris evecta. (Considerably reduced.)
B. Marattia fraxinea. Stipule. M.S.
The vascular system[749] of the stem constitutes a highly complex
dictyostelic or polycylic type which may consist of as many as nine
concentric series of strands of xylem surrounded by phloem, with large
sieve-tubes and a pericycle which abuts on the parenchymatous ground-
tissue without any definite endodermal layer. A peculiarity in the vascular
strands is that the first-formed elements of the phloem lie close to the edge
of the xylem, the metaphloem being therefore centrifugal in its
development. The ground-tissue is devoid of mechanical tissue and is
penetrated by roots, a few of which arise from the outer vascular strands
while others force their way to the surface from the more internal
dictyosteles. Leaf-traces, consisting of several strands, are given off from
the outermost cylinder and a segment of the second dictyostele moves out
to fill the gap formed in the outermost network, while the gap in the second
cylinder receives compensating strands from the third. A few layers below
the surface of the petiole there is a ring of thick-walled elements (s, fig.
243), and in both petiole and stem numerous mucilage ducts and tannin-
sacs occur in the ground-tissue. It has been shown by Farmer and Hill[750]
that in some of the vascular strands in an Angiopteris stem a few secondary
tracheae are added to the primary xylem by the activity of the adjacent
parenchyma. The vascular bundles in the petiole form more or less regular
Page 355
concentric series; they have no endodermis and are characterised also by the
large size of the sieve-tubes (st, fig. 243).
Fig. 242.
A–D. Angiopteris evecta.
A. Apex of sporangium showing “annulus.”
B. Sori.
C. Sporangium.
D. Section of sporangium, showing the two lateral bands of thick-walled cells.
E. Danaea: a, roof of synangium, with pores; b, sporangial cavities; v, vascular bundle; i,
indusium.
(D, after Zeiller.)
The roots of Marattiaceous ferns (fig. 244) are characterised by the larger
number of xylem and phloem groups; the stele is polyarch and not diarch,
tetrarch or hexarch as in most Leptosporangiate ferns.
large size of the sieve-tubes (st, fig. 243).
Fig. 242.
A–D. Angiopteris evecta.
A. Apex of sporangium showing “annulus.”
B. Sori.
C. Sporangium.
D. Section of sporangium, showing the two lateral bands of thick-walled cells.
E. Danaea: a, roof of synangium, with pores; b, sporangial cavities; v, vascular bundle; i,
indusium.
(D, after Zeiller.)
The roots of Marattiaceous ferns (fig. 244) are characterised by the larger
number of xylem and phloem groups; the stele is polyarch and not diarch,
tetrarch or hexarch as in most Leptosporangiate ferns.
Page 356
Fig. 243. Angiopteris evecta. Section of petiole (considerably reduced) and of a single
vascular bundle (magnified): px, protoxylem; st, sieve-tubes.
Fig. 244. Angiopteris evecta. Transverse section of root, with part of the stele magnified: s,
sieve-tubes; p, phloem; px, protoxylem.
Archangiopteris. This monotypic genus, discovered by Mr Henry in
South Eastern Yunnan, was described by Christ and Giesenhagen in
1899[751]. The comparatively slender rhizome has a fairly simple vascular
system[752]. The simply-pinnate leaves bear pinnules like those of Danaea,
but the sori agree with those of Angiopteris except in their greater length
and in the larger number of sporangia.
vascular bundle (magnified): px, protoxylem; st, sieve-tubes.
Fig. 244. Angiopteris evecta. Transverse section of root, with part of the stele magnified: s,
sieve-tubes; p, phloem; px, protoxylem.
Archangiopteris. This monotypic genus, discovered by Mr Henry in
South Eastern Yunnan, was described by Christ and Giesenhagen in
1899[751]. The comparatively slender rhizome has a fairly simple vascular
system[752]. The simply-pinnate leaves bear pinnules like those of Danaea,
but the sori agree with those of Angiopteris except in their greater length
and in the larger number of sporangia.
Page 357
Marattia. This genus, which extends “all round the world within the
tropics[753],” includes some species which closely resemble Angiopteris,
while others are characterised by more finely divided leaves with smaller
ultimate segments. The fleshy stipules occasionally have an irregularly
pinnatifid form (fig. 241, B). The sporangia are represented by oval
synangia[754] (fig. 245, A; the black patches at the ends of the lateral veins)
composed of two valves, which on ripening come apart and expose two
rows of pores formed by the apical dehiscence of the sporangial
compartments (fig. 245, A′, B). In Marattia Kaulfussii the sori are attached
to the lamina by a short stalk (fig. 245, B, B′) and the leaf bears a close
resemblance to those of the Umbelliferous genera Anthriscus and
Chaerophyllum. The vascular system is constructed on the same plan as that
of Angiopteris but is of simpler form.
tropics[753],” includes some species which closely resemble Angiopteris,
while others are characterised by more finely divided leaves with smaller
ultimate segments. The fleshy stipules occasionally have an irregularly
pinnatifid form (fig. 241, B). The sporangia are represented by oval
synangia[754] (fig. 245, A; the black patches at the ends of the lateral veins)
composed of two valves, which on ripening come apart and expose two
rows of pores formed by the apical dehiscence of the sporangial
compartments (fig. 245, A′, B). In Marattia Kaulfussii the sori are attached
to the lamina by a short stalk (fig. 245, B, B′) and the leaf bears a close
resemblance to those of the Umbelliferous genera Anthriscus and
Chaerophyllum. The vascular system is constructed on the same plan as that
of Angiopteris but is of simpler form.
Page 358
Fig. 245.
A. Marattia fraxinea. A′. A single synangium showing the two valves and pores of the
sporangial compartments.
B, B′. M. Kaulfussii.
C. Kaulfussia (synangium showing pores of sporangial compartments).
D, E. Marattiopsis Münsteri.
(C, after Hooker; D, E, after Schimper.)
Danaea. Danaea, represented by about 14 species confined to tropical
America, is characterised by simple or simply pinnate leaves with linear
segments bearing elongated sori extending from the midrib almost to the
margin of the lamina. Each sorus consists of numerous sporangia in two
parallel rows united into an oblong mass partially overarched by an
indusium (fig. 242, E, i) which grows up from the leaf between the sori. In
the portion of a fertile segment shown in fig. 242, E, the apical pores are
seen at a; and at b, where the roof of the synangium has been removed, the
spore-bearing compartments are exposed. The vascular system[755] agrees in
general plan with that characteristic of the family.
A. Marattia fraxinea. A′. A single synangium showing the two valves and pores of the
sporangial compartments.
B, B′. M. Kaulfussii.
C. Kaulfussia (synangium showing pores of sporangial compartments).
D, E. Marattiopsis Münsteri.
(C, after Hooker; D, E, after Schimper.)
Danaea. Danaea, represented by about 14 species confined to tropical
America, is characterised by simple or simply pinnate leaves with linear
segments bearing elongated sori extending from the midrib almost to the
margin of the lamina. Each sorus consists of numerous sporangia in two
parallel rows united into an oblong mass partially overarched by an
indusium (fig. 242, E, i) which grows up from the leaf between the sori. In
the portion of a fertile segment shown in fig. 242, E, the apical pores are
seen at a; and at b, where the roof of the synangium has been removed, the
spore-bearing compartments are exposed. The vascular system[755] agrees in
general plan with that characteristic of the family.
Page 359
Kaulfussia. The form of the leaf (Vol. I. p. 97, fig. 22) closely resembles
that of the Horse Chestnut; the stem is a creeping dorsiventral rhizome with
a vascular system in the form of a “much perforated solenostele[756].” The
synangia are circular, with a median depression; each sporangial
compartment opens by an apical pore on the sloping sides of the synangial
cup (fig. 245, C)[757].
Copeland has recently described a Marattiaceous leaf which he makes the
type of a new genus, Macroglossum alidae. The sori are nearer the margin
than in Angiopteris and are said to consist of a greater number of sporangia.
The photograph[758] of a single pinna which accompanies the brief
description hardly affords satisfactory evidence in support of the creation of
a new genus. The structure of a petiole which I have had an opportunity of
examining, through the kindness of Mr Hewitt of Sarawak, shows no
distinctive features.
III. Ophioglossales. (Isosporous and Eusporangiate.)
The three genera, Ophioglossum, Botrychium, and Helminthostachys, are
characterised by the division of the leaves into a sterile and a fertile lobe.
The fertile lobe in Ophioglossum bears two rows of spherical sporangia
sunk in its tissue; in Botrychium and Helminthostachys the spores are
contained in large sporangia with a stout wall[759]. The prothallus is
subterranean and without chlorophyll. In the British species of
Ophioglossum, O. vulgatum (the adder’s tongue fern), an almost
cosmopolitan species, the sterile part of the frond is of oval form and has
reticulate venation. In O. pendulum and O. palmatum the lamina is deeply
lobed. In the genus Botrychium, represented in Britain by B. Lunaria, both
sterile and fertile branches of the frond are pinnately divided, while in
Helminthostachys the sporangia are borne on sporangiophores given off
from the margin of the fertile branch of a frond similar in habit to a leaf of
Helleborus.
that of the Horse Chestnut; the stem is a creeping dorsiventral rhizome with
a vascular system in the form of a “much perforated solenostele[756].” The
synangia are circular, with a median depression; each sporangial
compartment opens by an apical pore on the sloping sides of the synangial
cup (fig. 245, C)[757].
Copeland has recently described a Marattiaceous leaf which he makes the
type of a new genus, Macroglossum alidae. The sori are nearer the margin
than in Angiopteris and are said to consist of a greater number of sporangia.
The photograph[758] of a single pinna which accompanies the brief
description hardly affords satisfactory evidence in support of the creation of
a new genus. The structure of a petiole which I have had an opportunity of
examining, through the kindness of Mr Hewitt of Sarawak, shows no
distinctive features.
III. Ophioglossales. (Isosporous and Eusporangiate.)
The three genera, Ophioglossum, Botrychium, and Helminthostachys, are
characterised by the division of the leaves into a sterile and a fertile lobe.
The fertile lobe in Ophioglossum bears two rows of spherical sporangia
sunk in its tissue; in Botrychium and Helminthostachys the spores are
contained in large sporangia with a stout wall[759]. The prothallus is
subterranean and without chlorophyll. In the British species of
Ophioglossum, O. vulgatum (the adder’s tongue fern), an almost
cosmopolitan species, the sterile part of the frond is of oval form and has
reticulate venation. In O. pendulum and O. palmatum the lamina is deeply
lobed. In the genus Botrychium, represented in Britain by B. Lunaria, both
sterile and fertile branches of the frond are pinnately divided, while in
Helminthostachys the sporangia are borne on sporangiophores given off
from the margin of the fertile branch of a frond similar in habit to a leaf of
Helleborus.
Page 360
Fig. 246. Ophioglossum vulgatum. Transverse section of petiole and single bundle: p,
phloem; px, endarch protoxylem.
Fig. 247. Botrychium virginianum: e, endodermis; c, cambium; x, xylem.
A, diagrammatic section of stem; B, portion of the stele and endodermis enlarged.
(A, after Campbell; B, after Jeffrey.)
The stem of Ophioglossum is characterised by a dictyostele of collateral
bundles with endarch protoxylem: the vascular system of the leaf-stalk is
also composed of several separate strands (fig. 246). In Botrychium the stele
is a cylinder of xylem surrounded externally by phloem. This genus affords
the only instance among ferns of a plant in which the addition of secondary
tracheae occurs on a scale large enough to produce a well-defined cylinder
of secondary xylem traversed by radial rows of medullary-ray cells[760] (fig.
phloem; px, endarch protoxylem.
Fig. 247. Botrychium virginianum: e, endodermis; c, cambium; x, xylem.
A, diagrammatic section of stem; B, portion of the stele and endodermis enlarged.
(A, after Campbell; B, after Jeffrey.)
The stem of Ophioglossum is characterised by a dictyostele of collateral
bundles with endarch protoxylem: the vascular system of the leaf-stalk is
also composed of several separate strands (fig. 246). In Botrychium the stele
is a cylinder of xylem surrounded externally by phloem. This genus affords
the only instance among ferns of a plant in which the addition of secondary
tracheae occurs on a scale large enough to produce a well-defined cylinder
of secondary xylem traversed by radial rows of medullary-ray cells[760] (fig.
Page 361
247). The unsatisfactory nature of the evidence in regard to the past history
of the Ophioglossales renders superfluous a fuller treatment of the recent
species.
of the Ophioglossales renders superfluous a fuller treatment of the recent
species.
Page 362
Page 363
CHAPTER XXI.
FOSSIL FERNS.
Osmundaceae.
From the Culm of Silesia, Stur[761] described impressions of sterile fronds
which he named Todea Lipoldi on the ground of the similarity of the finely
divided pinnules to those of Todea superba and other filmy species of the
genus. The type-specimen of Stur (in the Geological Survey Museum,
Vienna) affords no information as to sporangial characters and cannot be
accepted as an authentic record of a Lower Carboniferous representative of
the family. Another more satisfactory but hardly convincing piece of
evidence bearing on the presence of Osmundaceae in pre-Permian floras
has been adduced by Renault[762], who described petrified sporangia from
the Culm beds of Esnost in France as Todeopsis primaeva (fig. 256, F).
These pyriform sporangia are characterised by the presence of a plate of
large cells comparable with the subapical group of “annulus” cells in the
sporangia of the recent species (fig. 221).
Zeiller[763] has published a figure of some sporangia described by Renault
from Autun resembling the Osmundaceous type in having a plate of thick-
walled cells instead of a true annulus, but the plate is larger than the group
of cells in the recent sporangia, and both sporangia and spores are smaller
in the fossil. The sporangia from Carboniferous rocks described by Weiss as
Sturiella[764] bear some resemblance to those of recent Osmundaceae, but
there is no adequate reason for referring them to this family.
The generic name Pteridotheca is employed by Scott as a convenient
designation for unassigned petrified sporangia of Palaeozoic age with an
annulus and other characters indicating fern-affinity. In the species P.
Butterworthi[765] the sporangia are characterised by a group of large cells
suggesting comparison with the annulus, or what represents the annulus, in
Osmundaceae and Marattiaceae. Scott has also described a sporangium
FOSSIL FERNS.
Osmundaceae.
From the Culm of Silesia, Stur[761] described impressions of sterile fronds
which he named Todea Lipoldi on the ground of the similarity of the finely
divided pinnules to those of Todea superba and other filmy species of the
genus. The type-specimen of Stur (in the Geological Survey Museum,
Vienna) affords no information as to sporangial characters and cannot be
accepted as an authentic record of a Lower Carboniferous representative of
the family. Another more satisfactory but hardly convincing piece of
evidence bearing on the presence of Osmundaceae in pre-Permian floras
has been adduced by Renault[762], who described petrified sporangia from
the Culm beds of Esnost in France as Todeopsis primaeva (fig. 256, F).
These pyriform sporangia are characterised by the presence of a plate of
large cells comparable with the subapical group of “annulus” cells in the
sporangia of the recent species (fig. 221).
Zeiller[763] has published a figure of some sporangia described by Renault
from Autun resembling the Osmundaceous type in having a plate of thick-
walled cells instead of a true annulus, but the plate is larger than the group
of cells in the recent sporangia, and both sporangia and spores are smaller
in the fossil. The sporangia from Carboniferous rocks described by Weiss as
Sturiella[764] bear some resemblance to those of recent Osmundaceae, but
there is no adequate reason for referring them to this family.
The generic name Pteridotheca is employed by Scott as a convenient
designation for unassigned petrified sporangia of Palaeozoic age with an
annulus and other characters indicating fern-affinity. In the species P.
Butterworthi[765] the sporangia are characterised by a group of large cells
suggesting comparison with the annulus, or what represents the annulus, in
Osmundaceae and Marattiaceae. Scott has also described a sporangium
Page 364
from the Coal-Measures containing germinating spores[766]; the structure is
similar to that of recent Osmundaceous sporangia, and it is interesting to
note that germinating spores have been observed in the recent species Todea
hymenophylloides[767].
Additional evidence of the same kind is afforded by fertile specimens of
a quadripinnate fern with deeply dissected oval-lanceolate pinnules
described by Zeiller from the Coal-Measures of Heraclea in Asia Minor as
Kidstonia heracleensis[768] (fig. 256, E). Carbonised sporangia were found at
the base of narrow lobes of the ultimate segments and, as seen in fig. 256,
E, the sporangial wall is distinguished by a plate of larger cells occupying a
position like that of the “annulus” of recent Osmundaceae. Zeiller regards
the sporangia as intermediate between those of Osmundaceae and
Schizaeaceae. From the same locality Zeiller describes another frond
bearing somewhat similar sporangia as Sphenopteris (Discopteris) Rallii
(fig. 256, D)[769]: the term Discopteris was instituted by Stur for fertile
fronds referred by him to the Marattiaceae[770].
It is by no means safe to assume that these and such Upper Carboniferous
sporangia as Bower[771] compared with those of Todea were borne on plants
possessing the anatomical characters of Osmundaceae rather than those of
the extinct Palaeozoic family Botryopterideae. This brings us to the
important fact, first pointed out by Renault, that the Botryopterideae are
essentially generalised ferns exhibiting many points of contact with the
Osmundaceae[772]. It is clear that whether or not we are justified in tracing
the Osmundaceae as far back as the Lower Carboniferous period, some of
the characteristics of the family were already foreshadowed in rocks of this
age.
Through a fortunate accident of preservation, unequivocal evidence of
the existence of Osmundaceae in the Palaeozoic era is supplied by the
Russian Upper Permian genera Zalesskya and Thamnopteris.
Zalesskya.
This generic title has been instituted by Kidston and Gwynne-
Vaughan[773] for two Russian stems of Upper Permian age, one of which was
named by Eichwald[774] Chelepteris gracilis, but the probability that the type
similar to that of recent Osmundaceous sporangia, and it is interesting to
note that germinating spores have been observed in the recent species Todea
hymenophylloides[767].
Additional evidence of the same kind is afforded by fertile specimens of
a quadripinnate fern with deeply dissected oval-lanceolate pinnules
described by Zeiller from the Coal-Measures of Heraclea in Asia Minor as
Kidstonia heracleensis[768] (fig. 256, E). Carbonised sporangia were found at
the base of narrow lobes of the ultimate segments and, as seen in fig. 256,
E, the sporangial wall is distinguished by a plate of larger cells occupying a
position like that of the “annulus” of recent Osmundaceae. Zeiller regards
the sporangia as intermediate between those of Osmundaceae and
Schizaeaceae. From the same locality Zeiller describes another frond
bearing somewhat similar sporangia as Sphenopteris (Discopteris) Rallii
(fig. 256, D)[769]: the term Discopteris was instituted by Stur for fertile
fronds referred by him to the Marattiaceae[770].
It is by no means safe to assume that these and such Upper Carboniferous
sporangia as Bower[771] compared with those of Todea were borne on plants
possessing the anatomical characters of Osmundaceae rather than those of
the extinct Palaeozoic family Botryopterideae. This brings us to the
important fact, first pointed out by Renault, that the Botryopterideae are
essentially generalised ferns exhibiting many points of contact with the
Osmundaceae[772]. It is clear that whether or not we are justified in tracing
the Osmundaceae as far back as the Lower Carboniferous period, some of
the characteristics of the family were already foreshadowed in rocks of this
age.
Through a fortunate accident of preservation, unequivocal evidence of
the existence of Osmundaceae in the Palaeozoic era is supplied by the
Russian Upper Permian genera Zalesskya and Thamnopteris.
Zalesskya.
This generic title has been instituted by Kidston and Gwynne-
Vaughan[773] for two Russian stems of Upper Permian age, one of which was
named by Eichwald[774] Chelepteris gracilis, but the probability that the type
Page 365
of the genus Chelepteris is generically distinct from Eichwald’s species
necessitated a new designation for the Permian fern.
In habit the stem of Zalesskya resembles that of an Osmunda or a Todea,
but it differs in the possession of a stele composed of a continuous cylinder
or solid column of xylem surrounded by phloem, and by the differentiation
of the xylem into two concentric zones. The leaves are represented by
petiole-bases only; the sporangia are unknown. The stem and leaf-base
anatomy fully justifies the inclusion of Zalesskya in the Osmundaceae.
Zalesskya gracilis (Eichwald). Fig. 248.
The type-specimen is a partially decorticated stem, from Upper Permian
beds in Russia, provided with a single stele, 13 mm. in diameter,
surrounded by a broad thin-walled inner cortex containing numerous leaf-
traces and occasional roots: this was doubtless succeeded by a sclerotic
outer cortex. In its main features Zalesskya gracilis agrees closely with Z.
diploxylon represented in fig. 249. The stele consists of a continuous
cylinder of xylem exhibiting a fairly distinct differentiation into two zones,
(i) a broader outer zone of narrower scalariform tracheae (x ii, fig. 248) in
which 20 to 25 protoxylem strands (px) occur just within the edge, (ii) an
inner zone of broader and shorter tracheae (fig. 248, x i). The protoxylem
elements (px, fig. 248) are characterised by a single series of scalariform
pits, while the metaxylem elements have multiseriate pits like those on the
water-conducting elements of recent Osmundaceae. The tracheae show an
interesting histological character in the absence of the middle substance of
their walls, a feature recognised by Gwynne-Vaughan[775] in many recent
ferns. External to the xylem and separated from it by a parenchymatous
sheath is a ring of phloem, ph, composed of large sieve-tubes and
parenchyma separated from the inner cortex by a pericycle 4 to 5 layers in
breadth. The occurrence of a few sclerotic cells beyond the broad inner
cortex points to the former existence of a thick-walled outer cortex. The
leaf-traces are given off as mesarch strands from the edge of the xylem;
they begin as prominences opposite the protoxylem and become gradually
detached as xylem bundles, at first oblong in transverse section, then
assuming a slightly crescentic and reniform shape, while the mesarch
protoxylem strand takes up an endarch position. As a trace passes further
out the curvature increases and the protoxylem strands undergo repeated
necessitated a new designation for the Permian fern.
In habit the stem of Zalesskya resembles that of an Osmunda or a Todea,
but it differs in the possession of a stele composed of a continuous cylinder
or solid column of xylem surrounded by phloem, and by the differentiation
of the xylem into two concentric zones. The leaves are represented by
petiole-bases only; the sporangia are unknown. The stem and leaf-base
anatomy fully justifies the inclusion of Zalesskya in the Osmundaceae.
Zalesskya gracilis (Eichwald). Fig. 248.
The type-specimen is a partially decorticated stem, from Upper Permian
beds in Russia, provided with a single stele, 13 mm. in diameter,
surrounded by a broad thin-walled inner cortex containing numerous leaf-
traces and occasional roots: this was doubtless succeeded by a sclerotic
outer cortex. In its main features Zalesskya gracilis agrees closely with Z.
diploxylon represented in fig. 249. The stele consists of a continuous
cylinder of xylem exhibiting a fairly distinct differentiation into two zones,
(i) a broader outer zone of narrower scalariform tracheae (x ii, fig. 248) in
which 20 to 25 protoxylem strands (px) occur just within the edge, (ii) an
inner zone of broader and shorter tracheae (fig. 248, x i). The protoxylem
elements (px, fig. 248) are characterised by a single series of scalariform
pits, while the metaxylem elements have multiseriate pits like those on the
water-conducting elements of recent Osmundaceae. The tracheae show an
interesting histological character in the absence of the middle substance of
their walls, a feature recognised by Gwynne-Vaughan[775] in many recent
ferns. External to the xylem and separated from it by a parenchymatous
sheath is a ring of phloem, ph, composed of large sieve-tubes and
parenchyma separated from the inner cortex by a pericycle 4 to 5 layers in
breadth. The occurrence of a few sclerotic cells beyond the broad inner
cortex points to the former existence of a thick-walled outer cortex. The
leaf-traces are given off as mesarch strands from the edge of the xylem;
they begin as prominences opposite the protoxylem and become gradually
detached as xylem bundles, at first oblong in transverse section, then
assuming a slightly crescentic and reniform shape, while the mesarch
protoxylem strand takes up an endarch position. As a trace passes further
out the curvature increases and the protoxylem strands undergo repeated
Page 366
bifurcation; it assumes in fact the form and general type of structure met
with in the leaf-traces of Todea and Osmunda. Numerous diarch roots,
given off from the stele at points just below the outgoing leaf-traces, pass
outwards in a sinuous horizontal course through the cortex of the stem.
Fig. 248. Zalesskya gracilis (Eich.). Transverse section of part of the stele: ph, phloem; x i, x
ii, xylem; px, protoxylem. (After Kidston and Gwynne-Vaughan. × 20.)
with in the leaf-traces of Todea and Osmunda. Numerous diarch roots,
given off from the stele at points just below the outgoing leaf-traces, pass
outwards in a sinuous horizontal course through the cortex of the stem.
Fig. 248. Zalesskya gracilis (Eich.). Transverse section of part of the stele: ph, phloem; x i, x
ii, xylem; px, protoxylem. (After Kidston and Gwynne-Vaughan. × 20.)
Page 367
Fig. 249. Zalesskya diploxylon. Kidston and Gwynne-Vaughan. Transverse section of stem.
ph, phloem. (After Kidston and Gwynne-Vaughan. × 2½.)
In Zalesskya gracilis the xylem cylinder was probably wider in the living
plant than in the petrified stem. In Zalesskya diploxylon[776], in all
probability from the same Russian locality, there can be little doubt that the
xylem was originally solid to the centre (fig. 249). In this species also the
phloem forms a continuous band (ph, fig. 249) consisting of four to six
layers of sieve-tubes.
Thamnopteris.
Thamnopteris Schlechtendalii (Eich.). Figs. 250, 312, A, Frontispiece.
ph, phloem. (After Kidston and Gwynne-Vaughan. × 2½.)
In Zalesskya gracilis the xylem cylinder was probably wider in the living
plant than in the petrified stem. In Zalesskya diploxylon[776], in all
probability from the same Russian locality, there can be little doubt that the
xylem was originally solid to the centre (fig. 249). In this species also the
phloem forms a continuous band (ph, fig. 249) consisting of four to six
layers of sieve-tubes.
Thamnopteris.
Thamnopteris Schlechtendalii (Eich.). Figs. 250, 312, A, Frontispiece.
Page 368
In 1849 Brongniart[777] proposed the name Thamnopteris for a species of
fern from the Upper Permian of Russia originally described by Eichwald as
Anomopteris Schlechtendalii. A new name was employed by Brongniart on
the ground that the fossil was not generically identical with the species
previously named by him Anomopteris Mougeotii[778]. Eichwald’s specimen
has been thoroughly investigated by Kidston and Gwynne-Vaughan[779]. The
stem (Frontispiece) agrees in habit with those of Zalesskya and recent
Osmundaceae; on the exposed leaf-bases the action of the weather has
etched out the horse-shoe form of the vascular strands and laid bare
numerous branched roots boring their way through the petiole stumps. The
centre of the stem is occupied by a protostele 13 mm. in diameter consisting
of solid xylem separated by a parenchymatous sheath from a cylinder of
phloem. The xylem is composed mainly of an axial column of short and
broad reticulately pitted tracheae (fig. 250, b and Frontispiece),
distinguished from the sharply contrasted peripheral zone of normal
scalariform elements, a, by their thinner walls and more irregular shape.
The protoxylem, px, is represented by groups of narrower elements rather
deeply immersed in the peripheral part of the metaxylem. A many-layered
pericycle, per, and traces of an endodermis, en, succeed the phloem, ph,
which is characterised by several rows of large contiguous sieve-tubes;
beyond the endodermis is a broad thin-walled inner cortex. The leaf-traces
arise as in Zalesskya, but the protoxylem in Thamnopteris is at first central;
as the trace passes outwards a group of parenchyma appears immediately
internal to the protoxylem elements and gradually assumes the form of a
bay of thin-walled tissue on the inner concave face of the curved xylem.
The next stage is the repeated division of the protoxylem strand until, in the
sclerotic outer cortex, the traces acquire the Osmundaceous structure (fig.
312, A, p. 453). The petiole bases have stipular wings as in Todea and
Osmunda.
fern from the Upper Permian of Russia originally described by Eichwald as
Anomopteris Schlechtendalii. A new name was employed by Brongniart on
the ground that the fossil was not generically identical with the species
previously named by him Anomopteris Mougeotii[778]. Eichwald’s specimen
has been thoroughly investigated by Kidston and Gwynne-Vaughan[779]. The
stem (Frontispiece) agrees in habit with those of Zalesskya and recent
Osmundaceae; on the exposed leaf-bases the action of the weather has
etched out the horse-shoe form of the vascular strands and laid bare
numerous branched roots boring their way through the petiole stumps. The
centre of the stem is occupied by a protostele 13 mm. in diameter consisting
of solid xylem separated by a parenchymatous sheath from a cylinder of
phloem. The xylem is composed mainly of an axial column of short and
broad reticulately pitted tracheae (fig. 250, b and Frontispiece),
distinguished from the sharply contrasted peripheral zone of normal
scalariform elements, a, by their thinner walls and more irregular shape.
The protoxylem, px, is represented by groups of narrower elements rather
deeply immersed in the peripheral part of the metaxylem. A many-layered
pericycle, per, and traces of an endodermis, en, succeed the phloem, ph,
which is characterised by several rows of large contiguous sieve-tubes;
beyond the endodermis is a broad thin-walled inner cortex. The leaf-traces
arise as in Zalesskya, but the protoxylem in Thamnopteris is at first central;
as the trace passes outwards a group of parenchyma appears immediately
internal to the protoxylem elements and gradually assumes the form of a
bay of thin-walled tissue on the inner concave face of the curved xylem.
The next stage is the repeated division of the protoxylem strand until, in the
sclerotic outer cortex, the traces acquire the Osmundaceous structure (fig.
312, A, p. 453). The petiole bases have stipular wings as in Todea and
Osmunda.
Page 369
Fig. 250. Thamnopteris Schlechtendalii (Eich.). Part of stele: a, outer xylem; b, inner xylem.
(After Kidston and Gwynne-Vaughan. × 13.)
OSMUNDACEAE
The striking feature exhibited by these Permian plants is the structure of
the protostele, which in Thamnopteris and probably in Zalesskya diploxylon
consists of solid xylem surrounded by phloem: this may be regarded as the
primitive form of the Osmundaceous stele. In Osmunda regalis and in other
recent species of the genus the xylem cylinder has the form of a lattice-
work; in other words, the departure of each leaf-trace makes a gap in the
xylem and the overlapping of the foliar-gaps results in the separation of the
xylem into a number of distinct bundles. In Zalesskya gracilis the
continuity of the xylem is not broken by overlapping gaps; in this it agrees
with Lepidodendron. In Thamnopteris the centre of the stele was occupied
by a peculiar form of xylem obviously ill-adapted for conduction, but
(After Kidston and Gwynne-Vaughan. × 13.)
OSMUNDACEAE
The striking feature exhibited by these Permian plants is the structure of
the protostele, which in Thamnopteris and probably in Zalesskya diploxylon
consists of solid xylem surrounded by phloem: this may be regarded as the
primitive form of the Osmundaceous stele. In Osmunda regalis and in other
recent species of the genus the xylem cylinder has the form of a lattice-
work; in other words, the departure of each leaf-trace makes a gap in the
xylem and the overlapping of the foliar-gaps results in the separation of the
xylem into a number of distinct bundles. In Zalesskya gracilis the
continuity of the xylem is not broken by overlapping gaps; in this it agrees
with Lepidodendron. In Thamnopteris the centre of the stele was occupied
by a peculiar form of xylem obviously ill-adapted for conduction, but
Page 370
probably serving for water-storage and comparable with the short and broad
tracheae in Megaloxylon[780]. There is clearly a well-marked difference in
stelar anatomy between these two Permian genera and Todea and Osmunda:
this difference appears less when viewed in the light of the facts revealed by
a study of the Jurassic species Osmundites Dunlopi.
Fig. 251. Lonchopteris virginiensis. (After Fontaine. ½ nat. size.)
As possible examples of Triassic Osmundaceae reference may be made
to some species included in Stur’s genus Speirocarpus[781]. S. virginiensis
was originally described by Fontaine[782] from the Upper Triassic rocks of
Virginia as Lonchopteris virginiensis (fig. 251) and has recently been
figured by Leuthardt[783] from the Keuper of Basel. The sporangia, which
are scattered over the lower surface of the pinnules, are described as
globose-elliptical and as having a rudimentary apical annulus; no figures
have been published. In habit the frond agrees with Todites Williamsoni, but
the lateral veins form an anastomosing system like that in the Palaeozoic
genus Lonchopteris (fig. 290, B). There would seem to be an a priori
probability of this species being a representative of the Osmundaceae and
not, as Stur believed, of the Marattiaceae. Seeing that Lonchopteris is a
designation of a purely provisional kind, it would be convenient to institute
tracheae in Megaloxylon[780]. There is clearly a well-marked difference in
stelar anatomy between these two Permian genera and Todea and Osmunda:
this difference appears less when viewed in the light of the facts revealed by
a study of the Jurassic species Osmundites Dunlopi.
Fig. 251. Lonchopteris virginiensis. (After Fontaine. ½ nat. size.)
As possible examples of Triassic Osmundaceae reference may be made
to some species included in Stur’s genus Speirocarpus[781]. S. virginiensis
was originally described by Fontaine[782] from the Upper Triassic rocks of
Virginia as Lonchopteris virginiensis (fig. 251) and has recently been
figured by Leuthardt[783] from the Keuper of Basel. The sporangia, which
are scattered over the lower surface of the pinnules, are described as
globose-elliptical and as having a rudimentary apical annulus; no figures
have been published. In habit the frond agrees with Todites Williamsoni, but
the lateral veins form an anastomosing system like that in the Palaeozoic
genus Lonchopteris (fig. 290, B). There would seem to be an a priori
probability of this species being a representative of the Osmundaceae and
not, as Stur believed, of the Marattiaceae. Seeing that Lonchopteris is a
designation of a purely provisional kind, it would be convenient to institute
Page 371
a new generic name for Triassic species having the Lonchopteris venation,
which there are good reasons for regarding as Osmundaceous ferns.
Similarly Speirocarpus tenuifolius (Emmons) (= Acrostichites tenuifolius
Font.), which resembles Todites Williamsoni (see p. 339) not only in habit
and in the distribution of the sporangia but also in the venation, is probably
an Osmundaceous species.
Osmundites.
Osmundites Dunlopi, Kidston and Gwynne-Vaughan[784], fig. 252.
This species was found in Jurassic rocks in the Otago district of New
Zealand in association with Cladophlebis denticulata[785] (fig. 257). The
type-specimen forms part of a stem 17 mm. in diameter surrounded by a
broad mass of crowded leaf-bases. The stele consists of an almost
continuous xylem ring (fig. 252) enclosing a wide pith: the phloem and
inner cortex are not preserved but the peripheral region of the stem is
occupied by a sclerotic outer cortex. The mass of encasing leaf-bases
resolves itself on closer inspection into zones of foliage-leaf petioles and
the petioles of scale-leaves with an aborted lamina. A similar association of
two forms of leaf is seen in the existing American species Osmunda
Claytoniana and O. cinnamomea. The cortex and armour of leaf-bases are
penetrated by numerous diarch roots. The xylem cylinder, six to seven
tracheae broad, is characterised by the narrower diameter of its innermost
elements and—an important point—by the fact that the detachment of a
leaf-trace does not break the continuity of the xylem cylinder (fig. 252).
Each leaf-trace is at first elliptical in section; it then becomes curved
inwards and gradually assumes the horse-shoe form as in Zalesskya and in
the recent species. The single endarch protoxylem becomes subdivided until
in the petiole it is represented by 20 or more strands.
which there are good reasons for regarding as Osmundaceous ferns.
Similarly Speirocarpus tenuifolius (Emmons) (= Acrostichites tenuifolius
Font.), which resembles Todites Williamsoni (see p. 339) not only in habit
and in the distribution of the sporangia but also in the venation, is probably
an Osmundaceous species.
Osmundites.
Osmundites Dunlopi, Kidston and Gwynne-Vaughan[784], fig. 252.
This species was found in Jurassic rocks in the Otago district of New
Zealand in association with Cladophlebis denticulata[785] (fig. 257). The
type-specimen forms part of a stem 17 mm. in diameter surrounded by a
broad mass of crowded leaf-bases. The stele consists of an almost
continuous xylem ring (fig. 252) enclosing a wide pith: the phloem and
inner cortex are not preserved but the peripheral region of the stem is
occupied by a sclerotic outer cortex. The mass of encasing leaf-bases
resolves itself on closer inspection into zones of foliage-leaf petioles and
the petioles of scale-leaves with an aborted lamina. A similar association of
two forms of leaf is seen in the existing American species Osmunda
Claytoniana and O. cinnamomea. The cortex and armour of leaf-bases are
penetrated by numerous diarch roots. The xylem cylinder, six to seven
tracheae broad, is characterised by the narrower diameter of its innermost
elements and—an important point—by the fact that the detachment of a
leaf-trace does not break the continuity of the xylem cylinder (fig. 252).
Each leaf-trace is at first elliptical in section; it then becomes curved
inwards and gradually assumes the horse-shoe form as in Zalesskya and in
the recent species. The single endarch protoxylem becomes subdivided until
in the petiole it is represented by 20 or more strands.
Page 372
Fig. 252. Osmundites Dunlopi Kidst. and G.-V. Portion of xylem showing the departure of a
leaf-trace. (After Kidston and Gwynne-Vaughan; × 36.)
In the continuity of the xylem cylinder this species of Osmundites shows
a closer approach to Todea barbara or T. superba (fig. 221, B) than to
species of Osmunda; it differs from Zalesskya in having reached a further
stage in the reduction of a solid protostele to one composed of a xylem
cylinder enclosing a pith. This difference is of the same kind as that which
distinguishes the stele of Lepidodendron rhodumnense from L. Harcourtii.
In Lepidodendron short tracheae occasionally occur on the inner edge of the
xylem cylinder, and in recent species of Todea the same kind of reduced
tracheae are met with on the inner edge of the xylem[786]. In both cases the
short tracheae are probably vestiges of an axial strand of conducting
elements which in the course of evolution have been converted into
parenchymatous cells. In Lepidodendron vasculare the mixed parenchyma
and short tracheae in the centre of the stele represent an intermediate stage
in xylem reduction, and the arrangement in vertical rows of the medullary
parenchyma in Lepidodendron is precisely similar to that described by
Kidston and Gwynne-Vaughan in Thamnopteris. In both cases the rows of
superposed short cells have probably been produced by the transverse
septation of cells which began by elongating as if to form conducting tubes
leaf-trace. (After Kidston and Gwynne-Vaughan; × 36.)
In the continuity of the xylem cylinder this species of Osmundites shows
a closer approach to Todea barbara or T. superba (fig. 221, B) than to
species of Osmunda; it differs from Zalesskya in having reached a further
stage in the reduction of a solid protostele to one composed of a xylem
cylinder enclosing a pith. This difference is of the same kind as that which
distinguishes the stele of Lepidodendron rhodumnense from L. Harcourtii.
In Lepidodendron short tracheae occasionally occur on the inner edge of the
xylem cylinder, and in recent species of Todea the same kind of reduced
tracheae are met with on the inner edge of the xylem[786]. In both cases the
short tracheae are probably vestiges of an axial strand of conducting
elements which in the course of evolution have been converted into
parenchymatous cells. In Lepidodendron vasculare the mixed parenchyma
and short tracheae in the centre of the stele represent an intermediate stage
in xylem reduction, and the arrangement in vertical rows of the medullary
parenchyma in Lepidodendron is precisely similar to that described by
Kidston and Gwynne-Vaughan in Thamnopteris. In both cases the rows of
superposed short cells have probably been produced by the transverse
septation of cells which began by elongating as if to form conducting tubes
Page 373
and ended by assuming the form of vertical series of parenchymatous
elements.
Fig. 253. Osmundites Kolbei Sew. (⅓ nat. size.)
In another Jurassic species, Osmundites Gibbiana[787], the xylem is of the
Osmunda type and consists of about 20 strands instead of a continuous or
almost continuous cylinder.
elements.
Fig. 253. Osmundites Kolbei Sew. (⅓ nat. size.)
In another Jurassic species, Osmundites Gibbiana[787], the xylem is of the
Osmunda type and consists of about 20 strands instead of a continuous or
almost continuous cylinder.
Page 374
Fig. 254. Osmundites Kolbei. (Leaf-scars.)
Osmundites Kolbei Seward, figs. 253–255.
This species was founded on a specimen obtained by Mr Kolbe from the
Uitenhage series of Cape Colony[788]. The fossil flora and fauna of this
series point to its correlation with the Wealden or Neocomian strata of
Europe[789]. The type-specimen consists of several pieces of a stem (fig.
253) which reached a length of about 90 cm. On the weathered surface the
remains of petiole-bases are clearly seen and on the reverse side of the
smaller piece shown in the figure numerous sinuous roots are present in
association with the leaf-stalks. The depression c in the larger specimen
may mark the position of a branch: at a fig. 253 (enlarged in fig. 254, a) the
vascular strand of a petiole is exposed as a broad U-shaped band and at b
(fig. 254, b) the form of the petiole-bases is clearly shown[790]. With the stem
were found imperfectly preserved impressions of fronds referred to
Cladophlebis denticulata, a common type of leaf which was found also in
association with the slightly older New Zealand stem, Osmundites Dunlopi.
Osmundites Kolbei Seward, figs. 253–255.
This species was founded on a specimen obtained by Mr Kolbe from the
Uitenhage series of Cape Colony[788]. The fossil flora and fauna of this
series point to its correlation with the Wealden or Neocomian strata of
Europe[789]. The type-specimen consists of several pieces of a stem (fig.
253) which reached a length of about 90 cm. On the weathered surface the
remains of petiole-bases are clearly seen and on the reverse side of the
smaller piece shown in the figure numerous sinuous roots are present in
association with the leaf-stalks. The depression c in the larger specimen
may mark the position of a branch: at a fig. 253 (enlarged in fig. 254, a) the
vascular strand of a petiole is exposed as a broad U-shaped band and at b
(fig. 254, b) the form of the petiole-bases is clearly shown[790]. With the stem
were found imperfectly preserved impressions of fronds referred to
Cladophlebis denticulata, a common type of leaf which was found also in
association with the slightly older New Zealand stem, Osmundites Dunlopi.
Page 375
Fig. 255. Osmundites Kolbei Sew. Transverse section, from a photograph supplied by Dr
Kidston and Mr Gwynne-Vaughan. (2½ nat. size.)
An examination of the internal structure of the South African stem by Dr
Kidston and Mr Gwynne-Vaughan has revealed many interesting features,
which will be fully described in Part IV. of their Monograph on fossil
Osmundaceous stems. I am greatly indebted to these authors for allowing
me to publish the following note contributed by Dr Kidston:—
“The section of Osmundites Kolbei Seward, shown in fig. 255, presents
the usual appearance of an Osmundaceous stock. The parts contained in this
section are the stele, inner and outer cortex and a portion of the surrounding
Kidston and Mr Gwynne-Vaughan. (2½ nat. size.)
An examination of the internal structure of the South African stem by Dr
Kidston and Mr Gwynne-Vaughan has revealed many interesting features,
which will be fully described in Part IV. of their Monograph on fossil
Osmundaceous stems. I am greatly indebted to these authors for allowing
me to publish the following note contributed by Dr Kidston:—
“The section of Osmundites Kolbei Seward, shown in fig. 255, presents
the usual appearance of an Osmundaceous stock. The parts contained in this
section are the stele, inner and outer cortex and a portion of the surrounding
Page 376
mantle of concrescent leaf-bases. The whole specimen has suffered much
from pressure, but if restored to its original form the xylem ring must have
been about 19 mm. in diameter. The number of xylem strands is about fifty-
six and several of them are more or less joined as in the modern genus
Todea. The tracheae are of the typical Osmundaceous type, that is to say,
the pits are actual perforations and several series of them occur on each wall
of the larger tracheae.
“The most interesting structural characteristic of Osmundites Kolbei is
not well seen in the figure owing to the compression of the xylem ring. This
consists in the occurrence of tracheae in the pith. In fact, we have here a
mixed pith, composed of parenchyma and true tracheae, a condition which
connects the Osmundaceae with a parenchymatous medulla with those
possessing a solid xylem stele like Zalesskya and Thamnopteris and so
completes the series of transitions extending from the older and solid-steled
forms to the modern medullated members of the Osmundaceae.”
Osmundites skidegatensis, Penhallow.
This lower Cretaceous Canadian species, first described by Penhallow[791]
and more recently by Kidston and Gwynne-Vaughan[792], is remarkable for
the large size of the stem, the stele alone having a diameter of 2·4 cm.
Penhallow figures a fragment of a leaf bearing a superficial resemblance to
that of Osmunda Claytoniana, which may be the foliage borne by
Osmundites skidegatensis. The xylem cylinder is broken by the exit of leaf-
traces into 50 or more strands varying in size and shape, and it is
noteworthy that the phloem is also interrupted as each leaf-trace is given
off. In recent species the xylem cylinder is almost always interrupted, but
the phloem retains its continuity. In the Canadian fossil an internal band of
phloem occurs between the xylem and the pith, and this joins the external
phloem at each leaf-gap. This internal phloem finds an interesting parallel
in certain recent species[793], but in these the internal and external phloem do
not meet at the foliar gaps as they do in the extinct type. In Osmunda
cinnamomea the internal phloem occurs only at the regions of branching of
the stem stele; in the fossil it is always present.
It is clear that Osmundites skidegatensis represents the most complex
type of stem so far recognised in the Osmundaceae; it illustrates a stage in
from pressure, but if restored to its original form the xylem ring must have
been about 19 mm. in diameter. The number of xylem strands is about fifty-
six and several of them are more or less joined as in the modern genus
Todea. The tracheae are of the typical Osmundaceous type, that is to say,
the pits are actual perforations and several series of them occur on each wall
of the larger tracheae.
“The most interesting structural characteristic of Osmundites Kolbei is
not well seen in the figure owing to the compression of the xylem ring. This
consists in the occurrence of tracheae in the pith. In fact, we have here a
mixed pith, composed of parenchyma and true tracheae, a condition which
connects the Osmundaceae with a parenchymatous medulla with those
possessing a solid xylem stele like Zalesskya and Thamnopteris and so
completes the series of transitions extending from the older and solid-steled
forms to the modern medullated members of the Osmundaceae.”
Osmundites skidegatensis, Penhallow.
This lower Cretaceous Canadian species, first described by Penhallow[791]
and more recently by Kidston and Gwynne-Vaughan[792], is remarkable for
the large size of the stem, the stele alone having a diameter of 2·4 cm.
Penhallow figures a fragment of a leaf bearing a superficial resemblance to
that of Osmunda Claytoniana, which may be the foliage borne by
Osmundites skidegatensis. The xylem cylinder is broken by the exit of leaf-
traces into 50 or more strands varying in size and shape, and it is
noteworthy that the phloem is also interrupted as each leaf-trace is given
off. In recent species the xylem cylinder is almost always interrupted, but
the phloem retains its continuity. In the Canadian fossil an internal band of
phloem occurs between the xylem and the pith, and this joins the external
phloem at each leaf-gap. This internal phloem finds an interesting parallel
in certain recent species[793], but in these the internal and external phloem do
not meet at the foliar gaps as they do in the extinct type. In Osmunda
cinnamomea the internal phloem occurs only at the regions of branching of
the stem stele; in the fossil it is always present.
It is clear that Osmundites skidegatensis represents the most complex
type of stem so far recognised in the Osmundaceae; it illustrates a stage in
Page 377
elaboration of the primitive protostele in advance of that reached by any
existing species.
• • • • •
The primitive Osmundaceous stele was composed of solid xylem
surrounded by phloem (Thamnopteris and Zalesskya); at a later stage the
xylem cylinder lost its inner zone of wide and short tracheae and assumed
the form seen in Osmundites Kolbei, in which the centre of the stele
consists of parenchyma with some tracheae. Another type is represented by
O. Dowkeri in which the pith is composed wholly of parenchyma and the
xylem ring is continuous. From this type, by expansion of the xylem ring
and by the formation of overlapping leaf-gaps, the form represented by
Osmunda regalis was reached. Osmunda cinnamomea, with internal phloem
in the regions of stelar branching, probably represents a further stage, as
Kidston and Gwynne-Vaughan believe, in increasing complexity due to the
introduction of phloem from without through gaps produced by the
branching of the stele. In Osmundites skidegatensis the leaf-gaps became
wider and the external phloem projected deeper into the stele until a
continuous internal phloem zone was produced. This most elaborate type
proved less successful than the simpler forms which still survive.
Osmundites Sturii.
Impressions of fertile pinnae with narrow linear segments bearing
exannulate sporangia described by Raciborski from Lower Jurassic rocks in
Poland as Osmunda Sturii[794] may with some hesitation be included in the
list of Mesozoic Osmundaceae.
Osmundites Dowkeri.
Under this name Carruthers[795] described a petrified stem from Lower
Eocene beds at Herne Bay, which in the structure of the stele agrees closely
with the Jurassic species O. Gibbiana and conforms to the normal
Osmundaceous type. It is possible, as Gardner and Ettingshausen[796]
suggested, that the foliage of this species may be represented by some
existing species.
• • • • •
The primitive Osmundaceous stele was composed of solid xylem
surrounded by phloem (Thamnopteris and Zalesskya); at a later stage the
xylem cylinder lost its inner zone of wide and short tracheae and assumed
the form seen in Osmundites Kolbei, in which the centre of the stele
consists of parenchyma with some tracheae. Another type is represented by
O. Dowkeri in which the pith is composed wholly of parenchyma and the
xylem ring is continuous. From this type, by expansion of the xylem ring
and by the formation of overlapping leaf-gaps, the form represented by
Osmunda regalis was reached. Osmunda cinnamomea, with internal phloem
in the regions of stelar branching, probably represents a further stage, as
Kidston and Gwynne-Vaughan believe, in increasing complexity due to the
introduction of phloem from without through gaps produced by the
branching of the stele. In Osmundites skidegatensis the leaf-gaps became
wider and the external phloem projected deeper into the stele until a
continuous internal phloem zone was produced. This most elaborate type
proved less successful than the simpler forms which still survive.
Osmundites Sturii.
Impressions of fertile pinnae with narrow linear segments bearing
exannulate sporangia described by Raciborski from Lower Jurassic rocks in
Poland as Osmunda Sturii[794] may with some hesitation be included in the
list of Mesozoic Osmundaceae.
Osmundites Dowkeri.
Under this name Carruthers[795] described a petrified stem from Lower
Eocene beds at Herne Bay, which in the structure of the stele agrees closely
with the Jurassic species O. Gibbiana and conforms to the normal
Osmundaceous type. It is possible, as Gardner and Ettingshausen[796]
suggested, that the foliage of this species may be represented by some
Page 378
sterile Osmunda-like fragments recorded from the Middle Bagshot beds of
Bovey Tracey and Bournemouth as Osmunda lignitum.
Todites.
This generic name[797] has been applied to fossil ferns exhibiting in the
structure of the sporangia and in the general habit of the fertile fronds a
close resemblance to the recent species Todea barbara (fig. 221, D, p. 286).
Todites Williamsoni (Brongniart) figs. 256, B, C, G.
1828. Pecopteris Williamsonis, Brongniart, Prodrome, p. 57; Hist. vég.
foss., p. 324, Pl. cx. figs. 1 and 2.
— P. whitbiensis, Brongniart, Hist. vég. foss. p. 321, Pl. cix. figs. 2–4.
— P. tenuis, ibid. p. 322, Pl. cx. figs. 3, 4.
1829. Pecopteris recentior, Phillips, Geol. Yorks. p. 148, Pl. viii. fig. 15.
— P. curtata, ibid. Pl. viii. fig. 12.
1833. Neuropteris recentior, Lindley and Hutton, Foss. Flora, Vol. i. Pl.
lxviii.
— Pecopteris dentata, ibid. Vol. iii., Pl. clxix.
1836. Acrostichites Williamsonis, Goeppert, foss. Farn. p. 285.
1841. Neuropteris Goeppertiana, Muenster, in Goeppert, Gattungen foss.
Pflanz. Lief. 5 and 6, p. 104, Pls. viii.–x.
1856. Pecopteris Huttoniana, Zigno, Flor. foss. Oolit. Vol. i. p. 133.
1867. Acrostichites Goeppertianus, Schenk, Foss. Flor. Grenzsch. p. 44,
Pl. v. fig. 5, Pl. vii. fig. 2.
1883. A. linnaeaefolius, Fontaine, Older Mesoz. Flora Virginia, p. 25, Pls.
vi.–ix.
— A. rhombifolius, ibid. Pls. viii. xi.–xiv.
1885. Todea Williamsonis, Schenk, Palaeont. Vol. xxxi. p. 168, Pl. iii. fig.
3.
1889. Cladophlebis virginiensis, Fontaine, Potomac Flora, p. 70, Pl. iii.
figs. 3–8; Pl. iv. figs. 1, 4.
Bovey Tracey and Bournemouth as Osmunda lignitum.
Todites.
This generic name[797] has been applied to fossil ferns exhibiting in the
structure of the sporangia and in the general habit of the fertile fronds a
close resemblance to the recent species Todea barbara (fig. 221, D, p. 286).
Todites Williamsoni (Brongniart) figs. 256, B, C, G.
1828. Pecopteris Williamsonis, Brongniart, Prodrome, p. 57; Hist. vég.
foss., p. 324, Pl. cx. figs. 1 and 2.
— P. whitbiensis, Brongniart, Hist. vég. foss. p. 321, Pl. cix. figs. 2–4.
— P. tenuis, ibid. p. 322, Pl. cx. figs. 3, 4.
1829. Pecopteris recentior, Phillips, Geol. Yorks. p. 148, Pl. viii. fig. 15.
— P. curtata, ibid. Pl. viii. fig. 12.
1833. Neuropteris recentior, Lindley and Hutton, Foss. Flora, Vol. i. Pl.
lxviii.
— Pecopteris dentata, ibid. Vol. iii., Pl. clxix.
1836. Acrostichites Williamsonis, Goeppert, foss. Farn. p. 285.
1841. Neuropteris Goeppertiana, Muenster, in Goeppert, Gattungen foss.
Pflanz. Lief. 5 and 6, p. 104, Pls. viii.–x.
1856. Pecopteris Huttoniana, Zigno, Flor. foss. Oolit. Vol. i. p. 133.
1867. Acrostichites Goeppertianus, Schenk, Foss. Flor. Grenzsch. p. 44,
Pl. v. fig. 5, Pl. vii. fig. 2.
1883. A. linnaeaefolius, Fontaine, Older Mesoz. Flora Virginia, p. 25, Pls.
vi.–ix.
— A. rhombifolius, ibid. Pls. viii. xi.–xiv.
1885. Todea Williamsonis, Schenk, Palaeont. Vol. xxxi. p. 168, Pl. iii. fig.
3.
1889. Cladophlebis virginiensis, Fontaine, Potomac Flora, p. 70, Pl. iii.
figs. 3–8; Pl. iv. figs. 1, 4.
Page 379
Fig. 256.
A. Cladophlebis denticulata.
B, B′. Todites Williamsoni (fertile).
C. T. Williamsoni (sterile pinna).
D. Discopteris Rallii.
E, E′. Kidstonia heracleensis.
F. Todeopsis primaeva.
G. Todites Williamsoni (sporangium).
[B, C, from specimens (13491; 39234) in the British Museum (B, very slightly reduced; C,
½ nat. size); D, E, after Zeiller; F, after Renault; G, after Raciborski.]
It is hopeless to attempt to arrive at satisfactory conclusions in regard to
the applicability of the name Todites Williamsoni to the numerous fronds
from Jurassic and Rhaetic rocks, agreeing more or less closely with
Brongniart’s type-specimen. Specimens from the Rhaetic may not be
A. Cladophlebis denticulata.
B, B′. Todites Williamsoni (fertile).
C. T. Williamsoni (sterile pinna).
D. Discopteris Rallii.
E, E′. Kidstonia heracleensis.
F. Todeopsis primaeva.
G. Todites Williamsoni (sporangium).
[B, C, from specimens (13491; 39234) in the British Museum (B, very slightly reduced; C,
½ nat. size); D, E, after Zeiller; F, after Renault; G, after Raciborski.]
It is hopeless to attempt to arrive at satisfactory conclusions in regard to
the applicability of the name Todites Williamsoni to the numerous fronds
from Jurassic and Rhaetic rocks, agreeing more or less closely with
Brongniart’s type-specimen. Specimens from the Rhaetic may not be
Page 380
specifically identical with those from the Jurassic; the main point is that,
whether actually identical or not, both sets of fossils clearly represent the
same general type of Osmundaceous fern[798] and may for present purposes
be included under the same designation. The above synonymy, though by
no means complete[799], serves to illustrate the confusion which has existed
in regard to this widely spread type of Mesozoic fern.
Todites Williamsoni may be briefly described as follows:—
Frond bipinnate; long linear pinnae (20–30 cm.) of uniform breadth arise at an acute angle, or
in the lower part of a frond, almost at right angles, from a stout rachis. Closely set pinnules
attached by a broad base; slightly falcate, the side towards the rachis strongly convex and the
outer margin straight or concave and bulged outwards towards the base of each segment, margin
usually entire, or it may be slightly lobed. Fertile pinnules similar to the sterile; sporangia of the
Osmundaceous type and often scattered over the whole lower surface of the lamina (fig. 256, B,
B′, G). Venation of the Cladophlebis type (cf. fig. 256, A).
It is not always easy to distinguish Todites Williamsoni from
Cladophlebis denticulata, another common Jurassic fern, but in the latter
the pinnules are usually longer and relatively narrower and the rachis is
more slender (cf. fig. 256, B and 257). Schenk[800] and Raciborski[801] have
shown that the sporangia of Todites conform in the absence of a true
annulus to those of Todea (fig. 256, G) and Osmunda. Nathorst[802] has
recently figured a group of spores of Todites Williamsoni in illustration of
the use of the treatment of carbonised impressions with nitric acid and
potassium chlorate. This species, though widely distributed in Jurassic
rocks, is hardly distinguishable from the German Rhaetic fronds figured by
Schenk from Bayreuth as Acrostichites Goeppertianus[803], or from other
fossils referred to an unnecessarily large number of species by Fontaine[804]
from Upper Triassic rocks of Virginia[805].
It would seem from the paucity of later records of Osmundaceae that the
family reached its zenith in the Jurassic era. When we pass to the later
Tertiary and more recent deposits evidence is afforded in regard to the
geographical range of Osmunda regalis. It has been shown to occur in the
Pliocene forest-bed of Norfolk[806] as well as in Palaeolithic and Neolithic
deposits[807].
whether actually identical or not, both sets of fossils clearly represent the
same general type of Osmundaceous fern[798] and may for present purposes
be included under the same designation. The above synonymy, though by
no means complete[799], serves to illustrate the confusion which has existed
in regard to this widely spread type of Mesozoic fern.
Todites Williamsoni may be briefly described as follows:—
Frond bipinnate; long linear pinnae (20–30 cm.) of uniform breadth arise at an acute angle, or
in the lower part of a frond, almost at right angles, from a stout rachis. Closely set pinnules
attached by a broad base; slightly falcate, the side towards the rachis strongly convex and the
outer margin straight or concave and bulged outwards towards the base of each segment, margin
usually entire, or it may be slightly lobed. Fertile pinnules similar to the sterile; sporangia of the
Osmundaceous type and often scattered over the whole lower surface of the lamina (fig. 256, B,
B′, G). Venation of the Cladophlebis type (cf. fig. 256, A).
It is not always easy to distinguish Todites Williamsoni from
Cladophlebis denticulata, another common Jurassic fern, but in the latter
the pinnules are usually longer and relatively narrower and the rachis is
more slender (cf. fig. 256, B and 257). Schenk[800] and Raciborski[801] have
shown that the sporangia of Todites conform in the absence of a true
annulus to those of Todea (fig. 256, G) and Osmunda. Nathorst[802] has
recently figured a group of spores of Todites Williamsoni in illustration of
the use of the treatment of carbonised impressions with nitric acid and
potassium chlorate. This species, though widely distributed in Jurassic
rocks, is hardly distinguishable from the German Rhaetic fronds figured by
Schenk from Bayreuth as Acrostichites Goeppertianus[803], or from other
fossils referred to an unnecessarily large number of species by Fontaine[804]
from Upper Triassic rocks of Virginia[805].
It would seem from the paucity of later records of Osmundaceae that the
family reached its zenith in the Jurassic era. When we pass to the later
Tertiary and more recent deposits evidence is afforded in regard to the
geographical range of Osmunda regalis. It has been shown to occur in the
Pliocene forest-bed of Norfolk[806] as well as in Palaeolithic and Neolithic
deposits[807].
Page 381
Fig. 257. Cladophlebis denticulata. (From a specimen in the British Museum from the
Inferior Oolite rocks of Yorkshire. Slightly reduced.)
A fertile frond from the Molteno (Rhaetic) beds of South Africa referred
to Cladophlebis (Todites) Roesserti (Presl)[808] represents in all probability
an Osmundaceous fern closely allied to Todites Williamsoni. The same
species is described by Zeiller[809] from Rhaetic rocks of Tonkin and very
similar types are figured by Leuthardt[810] from Upper Triassic rocks of
Basel as Pecopteris Rutimeyeri Heer, and by Fontaine[811] from rocks of the
same age in Virginia.
Cladophlebis.
The generic name Cladophlebis was instituted by Brongniart for
Mesozoic fern fronds characterised by ultimate segments of linear or more
Inferior Oolite rocks of Yorkshire. Slightly reduced.)
A fertile frond from the Molteno (Rhaetic) beds of South Africa referred
to Cladophlebis (Todites) Roesserti (Presl)[808] represents in all probability
an Osmundaceous fern closely allied to Todites Williamsoni. The same
species is described by Zeiller[809] from Rhaetic rocks of Tonkin and very
similar types are figured by Leuthardt[810] from Upper Triassic rocks of
Basel as Pecopteris Rutimeyeri Heer, and by Fontaine[811] from rocks of the
same age in Virginia.
Cladophlebis.
The generic name Cladophlebis was instituted by Brongniart for
Mesozoic fern fronds characterised by ultimate segments of linear or more
Page 382
or less falcate form attached to the pinnae by the whole of the base, as in the
Palaeozoic genus Pecopteris, possessing a midrib strongly marked at the
base and dividing towards the distal end of the lamina into finer branches
and giving off secondary forked and arched veins at an acute angle. The
term is generally restricted to Mesozoic fern fronds which, on account of
the absence or imperfection of fertile pinnae, cannot be safely assigned to a
particular family. In the case of the species described below, the evidence in
regard to systematic position, though not conclusive, is sufficiently strong
to justify its inclusion in the Osmundaceae.
Cladophlebis denticulata Brongniart. Figs. 256, A; 257, 258.
1828. Pecopteris denticulata[812], Brongniart, Prodrome, p. 57; Hist. vég.
foss. p. 301, Pl. xcviii. figs. 1, 2.
— P. Phillipsii, Brongniart, Hist. p. 304, Pl. cix. fig. 1.
This species is often confused[813] with Todites Williamsoni. The name
Pecopteris whitbiensis has been used by different writers for Jurassic fronds
which are undoubtedly specifically distinct: specimens so named by
Brongniart should be referred to Todites Williamsoni, while P. whitbiensis
of Lindley and Hutton[814] is Brongniart’s Cladophlebis denticulata. It is
impossible to determine with accuracy the numerous examples described as
Pecopteris whitbiensis, Asplenium whitbiense, Cladophlebis Albertsii (a
Wealden species[815]), Asplenium, or Cladophlebis, nebbense[816], etc., from
Jurassic and Rhaetic strata. The Cladophlebis denticulata form of frond is
one of the commonest in recent ferns; it is represented by such species as
Onoclea Struthopteris, Pteris arguta, Sadleria sp., Gleichenia dubia,
Alsophila lunulata, Cyathea dealbata, and species of Polypodium. It is,
therefore, not surprising to find records of this Mesozoic species from many
localities and horizons. All that we can do is to point out what appear to be
the most probable cases of identity among the numerous examples of fronds
of this type from Mesozoic rocks, particularly Rhaetic and Jurassic, in
different parts of the world. The name Cladophlebis denticulata may be
employed in a comprehensive sense for fronds showing the following
characters:—
Leaf large, bipinnate, with long spreading pinnae borne on a comparatively slender rachis.
Pinnules, in nearly all cases, sterile, reaching a length of 3–4cm., acutely pointed, finely
denticulate or entire, attached by the whole of the base (fig. 257). In the apical region the
Palaeozoic genus Pecopteris, possessing a midrib strongly marked at the
base and dividing towards the distal end of the lamina into finer branches
and giving off secondary forked and arched veins at an acute angle. The
term is generally restricted to Mesozoic fern fronds which, on account of
the absence or imperfection of fertile pinnae, cannot be safely assigned to a
particular family. In the case of the species described below, the evidence in
regard to systematic position, though not conclusive, is sufficiently strong
to justify its inclusion in the Osmundaceae.
Cladophlebis denticulata Brongniart. Figs. 256, A; 257, 258.
1828. Pecopteris denticulata[812], Brongniart, Prodrome, p. 57; Hist. vég.
foss. p. 301, Pl. xcviii. figs. 1, 2.
— P. Phillipsii, Brongniart, Hist. p. 304, Pl. cix. fig. 1.
This species is often confused[813] with Todites Williamsoni. The name
Pecopteris whitbiensis has been used by different writers for Jurassic fronds
which are undoubtedly specifically distinct: specimens so named by
Brongniart should be referred to Todites Williamsoni, while P. whitbiensis
of Lindley and Hutton[814] is Brongniart’s Cladophlebis denticulata. It is
impossible to determine with accuracy the numerous examples described as
Pecopteris whitbiensis, Asplenium whitbiense, Cladophlebis Albertsii (a
Wealden species[815]), Asplenium, or Cladophlebis, nebbense[816], etc., from
Jurassic and Rhaetic strata. The Cladophlebis denticulata form of frond is
one of the commonest in recent ferns; it is represented by such species as
Onoclea Struthopteris, Pteris arguta, Sadleria sp., Gleichenia dubia,
Alsophila lunulata, Cyathea dealbata, and species of Polypodium. It is,
therefore, not surprising to find records of this Mesozoic species from many
localities and horizons. All that we can do is to point out what appear to be
the most probable cases of identity among the numerous examples of fronds
of this type from Mesozoic rocks, particularly Rhaetic and Jurassic, in
different parts of the world. The name Cladophlebis denticulata may be
employed in a comprehensive sense for fronds showing the following
characters:—
Leaf large, bipinnate, with long spreading pinnae borne on a comparatively slender rachis.
Pinnules, in nearly all cases, sterile, reaching a length of 3–4cm., acutely pointed, finely
denticulate or entire, attached by the whole of the base (fig. 257). In the apical region the
Page 383
pinnules become shorter and broader. Venation of the Cladophlebis type (fig. 256, A). Fertile
pinnules rather straighter than the sterile, characterised by linear sori parallel to the lateral veins
(fig. 258).
In endeavouring to distinguish specifically between fronds showing a
general agreement in habit with C. denticulata, special attention should be
paid to venation characters, the shape of the pinnules, the relation of the two
edges of the lamina to one another, and to the amount of curvature of the
whole pinnule. Unless the material is abundant, it is often impossible to
distinguish between characters of specific value and others which are the
expression of differences in age or of position on a large frond, to say
nothing of the well-known variability which is amply illustrated by recent
ferns. It is remarkable that very few specimens are known which throw any
light on the nature of the fertile pinnae. Fig. 258 represents an impression
from the Inferior Oolite rocks of the Yorkshire coast in which the exposed
upper surface of the pinnules shows a series of parallel ridges following the
course of the lateral veins and no doubt formed by oblong sori on the lower
surface. There can be little doubt that the specimen figured by Lindley and
Hutton and by others as Pecopteris undans[817] is, as Nathorst suggests, a
portion of a fertile frond of C. denticulata. A fertile specimen of a frond
resembling in habit C. denticulata, which Fontaine has described from the
Jurassic rocks of Oregon as Danaeopsis Storrsii[818], exhibits, as that author
points out, a superficial resemblance to the specimen named by Lindley and
Hutton Pecopteris undans. There is, however, no adequate reason for
referring the American fragment to the Marattiaceae. In the absence of
sporangia we cannot speak confidently as to the systematic position of this
common type; but there are fairly good grounds for the assertion that some
at least of the fronds described under this name are those of Osmundaceae.
The English specimen shown in fig. 258 is very similar to some Indian
fossils figured by Feistmantel as Asplenites macrocarpus[819], which are
probably identical with Pecopteris australis Morris[820], a fern that is
indistinguishable from Cladophlebis denticulata. Renault[821] figured a
fertile specimen of the Australian fossil as Todea australis, which agrees
very closely with that shown in fig. 258, and the sporangia figured by the
French author are of the Osmundaceous type. Another example of a fertile
specimen is afforded by a Rhaetic fern from Franconia, Asplenites ottonis,
which is probably identical with Alethopteris Roesserti Presl [=
Cladophlebis (Todites) Roesserti], a plant closely resembling Cladophlebis
pinnules rather straighter than the sterile, characterised by linear sori parallel to the lateral veins
(fig. 258).
In endeavouring to distinguish specifically between fronds showing a
general agreement in habit with C. denticulata, special attention should be
paid to venation characters, the shape of the pinnules, the relation of the two
edges of the lamina to one another, and to the amount of curvature of the
whole pinnule. Unless the material is abundant, it is often impossible to
distinguish between characters of specific value and others which are the
expression of differences in age or of position on a large frond, to say
nothing of the well-known variability which is amply illustrated by recent
ferns. It is remarkable that very few specimens are known which throw any
light on the nature of the fertile pinnae. Fig. 258 represents an impression
from the Inferior Oolite rocks of the Yorkshire coast in which the exposed
upper surface of the pinnules shows a series of parallel ridges following the
course of the lateral veins and no doubt formed by oblong sori on the lower
surface. There can be little doubt that the specimen figured by Lindley and
Hutton and by others as Pecopteris undans[817] is, as Nathorst suggests, a
portion of a fertile frond of C. denticulata. A fertile specimen of a frond
resembling in habit C. denticulata, which Fontaine has described from the
Jurassic rocks of Oregon as Danaeopsis Storrsii[818], exhibits, as that author
points out, a superficial resemblance to the specimen named by Lindley and
Hutton Pecopteris undans. There is, however, no adequate reason for
referring the American fragment to the Marattiaceae. In the absence of
sporangia we cannot speak confidently as to the systematic position of this
common type; but there are fairly good grounds for the assertion that some
at least of the fronds described under this name are those of Osmundaceae.
The English specimen shown in fig. 258 is very similar to some Indian
fossils figured by Feistmantel as Asplenites macrocarpus[819], which are
probably identical with Pecopteris australis Morris[820], a fern that is
indistinguishable from Cladophlebis denticulata. Renault[821] figured a
fertile specimen of the Australian fossil as Todea australis, which agrees
very closely with that shown in fig. 258, and the sporangia figured by the
French author are of the Osmundaceous type. Another example of a fertile
specimen is afforded by a Rhaetic fern from Franconia, Asplenites ottonis,
which is probably identical with Alethopteris Roesserti Presl [=
Cladophlebis (Todites) Roesserti], a plant closely resembling Cladophlebis
Page 384
denticulata. Another argument in favour of including C. denticulata in the
Osmundaceae is supplied by the association of pinnae of this type with the
petrified stem of Osmundites Dunlopi recorded by Kidston and Gwynne-
Vaughan.
Fig. 258. Fertile pinnae of Cladophlebis denticulata. (From a Yorkshire specimen in the
Sedgwick Museum, Cambridge.)
Schizaeaceae.
Evidence bearing on the existence of this family in Carboniferous floras
is by no means decisive. The generic name Aneimites proposed by
Dawson[822] for some Devonian Canadian plants resembling species of the
recent genus Aneimia, and adopted by White[823] for a species from the
Pottsville beds of Virginia, is misleading. The Canadian plants give no
indication of the nature of the reproductive organs, and the fronds described
by White are, as he shows, those of a Pteridosperm and bore seeds.
An examination of the suspiciously diagrammatic drawings published by
Corda[824] of the small fertile pinnules of a Carboniferous fern from
Bohemia, which he named Senftenbergia elegans, leads us to conclude that
the sporangia are almost certainly those of a Schizaeaceous species. The
small linear pinnules bear two rows of sessile sporangia, singly as in recent
Osmundaceae is supplied by the association of pinnae of this type with the
petrified stem of Osmundites Dunlopi recorded by Kidston and Gwynne-
Vaughan.
Fig. 258. Fertile pinnae of Cladophlebis denticulata. (From a Yorkshire specimen in the
Sedgwick Museum, Cambridge.)
Schizaeaceae.
Evidence bearing on the existence of this family in Carboniferous floras
is by no means decisive. The generic name Aneimites proposed by
Dawson[822] for some Devonian Canadian plants resembling species of the
recent genus Aneimia, and adopted by White[823] for a species from the
Pottsville beds of Virginia, is misleading. The Canadian plants give no
indication of the nature of the reproductive organs, and the fronds described
by White are, as he shows, those of a Pteridosperm and bore seeds.
An examination of the suspiciously diagrammatic drawings published by
Corda[824] of the small fertile pinnules of a Carboniferous fern from
Bohemia, which he named Senftenbergia elegans, leads us to conclude that
the sporangia are almost certainly those of a Schizaeaceous species. The
small linear pinnules bear two rows of sessile sporangia, singly as in recent
Page 385
Schizaeaceae and not in sori, characterised by 4–5 rows of regular annular
cells (fig. 270, A) surrounding the apex. It has already been pointed out that
the apical annulus of recent Schizaeaceae, though normally one row deep,
may consist in part at least of two rows. Zeiller[825] examined specimens of
Corda’s species and decided in favour of a Schizaeaceous affinity; he
describes the sporangia as 0·85–0·95 mm. in length, with 3 to 5 and
occasionally only two rows of cells in the apical annulus. Zeiller’s figures
(fig. 270, A) confirm the impression that Corda’s drawings are more
beautiful than accurate. Stur[826], on the other hand, who first pointed out
that the type-specimens of Senftenbergia came from the Radnitz beds of
Bohemia and not from the Coal-Measures, convinced himself that the
sporangia have no true annulus (fig. 270, E). He describes them as
characterised by a comparatively strong wall and by the presence of a band
of narrow vertical cells marking the line of dehiscence, features which lead
him to assign the plant to the Marattiales, a group which seems to have
exercised a dominating influence over his judgment. In a later publication
Zeiller[827] replies to Stur’s criticism but adheres to his original opinion.
Solms-Laubach[828], while expressing himself in favour of Marattiaceous
affinity, recognises that Zeiller’s arguments cannot be set aside.
The question must remain open until further evidence is forthcoming; but
it would seem that this Carboniferous type, not as yet recognised in Britain,
possessed sporangia having a distinct resemblance to those of the
Schizaeaceae, though this similarity does not amount to proof of the
existence of the family in the Palaeozoic era.
Palaeozoic floras may be described as rich in generalised types, types
foreshadowing lines of evolution, which in the course of ages led to a
sorting and a redistribution of characters. It may be that Senftenbergia is
one of these generalised types.
• • • • •
It is not until we ascend the geological series as far as the older Jurassic
rocks that we meet with a type which can with confidence be classed with
the Schizaeaceae, as least so far as sporangial characters are concerned. The
cells (fig. 270, A) surrounding the apex. It has already been pointed out that
the apical annulus of recent Schizaeaceae, though normally one row deep,
may consist in part at least of two rows. Zeiller[825] examined specimens of
Corda’s species and decided in favour of a Schizaeaceous affinity; he
describes the sporangia as 0·85–0·95 mm. in length, with 3 to 5 and
occasionally only two rows of cells in the apical annulus. Zeiller’s figures
(fig. 270, A) confirm the impression that Corda’s drawings are more
beautiful than accurate. Stur[826], on the other hand, who first pointed out
that the type-specimens of Senftenbergia came from the Radnitz beds of
Bohemia and not from the Coal-Measures, convinced himself that the
sporangia have no true annulus (fig. 270, E). He describes them as
characterised by a comparatively strong wall and by the presence of a band
of narrow vertical cells marking the line of dehiscence, features which lead
him to assign the plant to the Marattiales, a group which seems to have
exercised a dominating influence over his judgment. In a later publication
Zeiller[827] replies to Stur’s criticism but adheres to his original opinion.
Solms-Laubach[828], while expressing himself in favour of Marattiaceous
affinity, recognises that Zeiller’s arguments cannot be set aside.
The question must remain open until further evidence is forthcoming; but
it would seem that this Carboniferous type, not as yet recognised in Britain,
possessed sporangia having a distinct resemblance to those of the
Schizaeaceae, though this similarity does not amount to proof of the
existence of the family in the Palaeozoic era.
Palaeozoic floras may be described as rich in generalised types, types
foreshadowing lines of evolution, which in the course of ages led to a
sorting and a redistribution of characters. It may be that Senftenbergia is
one of these generalised types.
• • • • •
It is not until we ascend the geological series as far as the older Jurassic
rocks that we meet with a type which can with confidence be classed with
the Schizaeaceae, as least so far as sporangial characters are concerned. The
Page 386
species Klukia exilis is selected as the best known and most widely-spread
representative of Jurassic Schizaeaceae.
Klukia exilis (Phillips)[829]. Fig. 259.
The generic name Klukia was proposed by Raciborski[830] for a species
originally described by Phillips[831] from the Inferior Oolite of the Yorkshire
coast as Pecopteris exilis. Bunbury’s[832] discovery (supplemented by
additional evidence obtained by Raciborski) of well-preserved sporangia
justified the substitution of a distinctive designation for the provisional term
Pecopteris.
Fig. 259. Klukia exilis (Phillips). (Figs. 1–3, × 40; fig. 4, × 3; fig. 5, nat. size.)
The species may be defined as follows:—
Frond tripinnate, of the Cladophlebis type; pinnae linear, lanceolate, attached to the rachis at a
wide angle. Ultimate segments short and linear, entire or, in the lower part of a frond, crenulate, 5
mm. long or occasionally longer. Sporangia 0·5 mm. in length, borne singly on the lower surface
of the lamina in a row on each side of the midrib.
A re-examination[833] of the specimen described by Bunbury confirmed
his account of the structure of the sporangia. The pinna shown in fig. 259 is
characterised by unusually small fertile pinnules some of which bear 10
sporangia in two rows; the annulus includes about 14 cells. Fertile
specimens of this and similar forms are figured by Raciborski[834] from
Jurassic rocks of Poland, and good examples of the English species may be
representative of Jurassic Schizaeaceae.
Klukia exilis (Phillips)[829]. Fig. 259.
The generic name Klukia was proposed by Raciborski[830] for a species
originally described by Phillips[831] from the Inferior Oolite of the Yorkshire
coast as Pecopteris exilis. Bunbury’s[832] discovery (supplemented by
additional evidence obtained by Raciborski) of well-preserved sporangia
justified the substitution of a distinctive designation for the provisional term
Pecopteris.
Fig. 259. Klukia exilis (Phillips). (Figs. 1–3, × 40; fig. 4, × 3; fig. 5, nat. size.)
The species may be defined as follows:—
Frond tripinnate, of the Cladophlebis type; pinnae linear, lanceolate, attached to the rachis at a
wide angle. Ultimate segments short and linear, entire or, in the lower part of a frond, crenulate, 5
mm. long or occasionally longer. Sporangia 0·5 mm. in length, borne singly on the lower surface
of the lamina in a row on each side of the midrib.
A re-examination[833] of the specimen described by Bunbury confirmed
his account of the structure of the sporangia. The pinna shown in fig. 259 is
characterised by unusually small fertile pinnules some of which bear 10
sporangia in two rows; the annulus includes about 14 cells. Fertile
specimens of this and similar forms are figured by Raciborski[834] from
Jurassic rocks of Poland, and good examples of the English species may be
Page 387
seen in the Leckenby collection, Cambridge, in the British Museum, the
museums of Manchester, Scarborough, and other places.
It is possible that specimens referred to K. exilis by Yokoyama[835] from
Wealden strata in Japan may afford evidence of the persistence of the
species beyond the Jurassic era, but in view of the close resemblance of the
sterile fronds described from Wealden strata as Cladophlebis Brownii[2]
and C. Dunkeri[836] to those of Klukia exilis, identity can be established only
by an examination of fertile specimens. A Jurassic fern recently described
by Yabe[837] from Korea as Cladophlebis koraiensis may be identical with K.
exilis and there is little doubt as to the existence of the species in Jurassic
Caucasian strata[838].
museums of Manchester, Scarborough, and other places.
It is possible that specimens referred to K. exilis by Yokoyama[835] from
Wealden strata in Japan may afford evidence of the persistence of the
species beyond the Jurassic era, but in view of the close resemblance of the
sterile fronds described from Wealden strata as Cladophlebis Brownii[2]
and C. Dunkeri[836] to those of Klukia exilis, identity can be established only
by an examination of fertile specimens. A Jurassic fern recently described
by Yabe[837] from Korea as Cladophlebis koraiensis may be identical with K.
exilis and there is little doubt as to the existence of the species in Jurassic
Caucasian strata[838].
Page 388
Fig. 260. Ruffordia Goepperti. (A, C, sterile; B, fertile; slightly reduced. Specimens from the
Wealden of Sussex; British Museum; V. 2333, V. 2160, V. 2166.)
Ruffordia Goepperti (Dunk.). Fig. 260.
This Wealden fern[839] has been doubtfully assigned to the Schizaeaceae
on the ground of the resemblance of the sterile fronds to those of some
species of Aneimia, and because of the difference between the sterile and
fertile pinnae (Fig. 260). Ruffordia cannot be regarded as a well
authenticated member of the Schizaeaceae.
Wealden of Sussex; British Museum; V. 2333, V. 2160, V. 2166.)
Ruffordia Goepperti (Dunk.). Fig. 260.
This Wealden fern[839] has been doubtfully assigned to the Schizaeaceae
on the ground of the resemblance of the sterile fronds to those of some
species of Aneimia, and because of the difference between the sterile and
fertile pinnae (Fig. 260). Ruffordia cannot be regarded as a well
authenticated member of the Schizaeaceae.
Page 389
Fig. 261.
A, A′. Chrysodium lanzaeanum.
B, B′. Lygodium Kaulfussi.
C. Marattia Hookeri.
(After Gardner and Ettingshausen; A, B, ¾ nat. size.)
Lygodium Kaulfussi, Heer. Fig. 261, B, B′.
Fragments of forked pinnules, agreeing very closely in venation and
general appearance with recent species of Lygodium, have been identified
by Gardner and Ettingshausen[840] from English Eocene beds and by
Knowlton from the Miocene beds of the Yellowstone Park[841] as Lygodium
Kaulfussi Heer (fig. 261, B). Despite the absence of sporangia it is probable
that these fragments are correctly referred to the Schizaeaceae. The sterile
and fertile specimens figured by Heer[842] from Tertiary beds of Switzerland
agree very closely with recent examples of Lygodium. Similar though
A, A′. Chrysodium lanzaeanum.
B, B′. Lygodium Kaulfussi.
C. Marattia Hookeri.
(After Gardner and Ettingshausen; A, B, ¾ nat. size.)
Lygodium Kaulfussi, Heer. Fig. 261, B, B′.
Fragments of forked pinnules, agreeing very closely in venation and
general appearance with recent species of Lygodium, have been identified
by Gardner and Ettingshausen[840] from English Eocene beds and by
Knowlton from the Miocene beds of the Yellowstone Park[841] as Lygodium
Kaulfussi Heer (fig. 261, B). Despite the absence of sporangia it is probable
that these fragments are correctly referred to the Schizaeaceae. The sterile
and fertile specimens figured by Heer[842] from Tertiary beds of Switzerland
agree very closely with recent examples of Lygodium. Similar though
Page 390
perhaps less convincing evidence of the existence of this family in Europe
is furnished by Saporta[843], who described two Eocene species from France.
Gleicheniaceae.
The application by Goeppert[844] and other earlier writers of the generic
name Gleichenites to examples of Palaeozoic ferns was not justified by any
satisfactory evidence. One of Goeppert’s species, Gleichenites
neuropteroides, is identical with Neuropteris heterophylla[845], a plant now
included in the Pteridosperms.
The resemblance of sporangia and sori, whether preserved as carbonised
impressions or as petrified material, from Carboniferous rocks, to those of
recent species of Gleicheniaceae is in many cases at least the result of
misinterpretation of deceptive appearances. Williamson[846] drew attention to
the Gleichenia-like structure of some sections of sporangia from the English
Coal-Measures, but he did not realise the ease with which sections of
Marattiaceous sporangia in different planes may be mistaken for those of
annulate (leptosporangiate) sporangia. In the regular dichotomous habit of
Carboniferous fronds described as species of Diplothmema (Stur) and
Mariopteris (Zeiller)[847] we have a close correspondence with the leaves of
Gleichenia, but the common occurrence of dichotomous branching among
ferns is sufficient reason for regarding this feature as an untrustworthy
criterion of relationship. It is, however, interesting to find that in addition to
the existence of some Upper Carboniferous ferns with sori like those of
recent Gleichenias, the type of stelar anatomy illustrated by Gleichenia
dicarpa (fig. 237, C, p. 310) and other species is characteristic of the
primary structure of the stem of the Pteridosperm Heterangium. We find in
Carboniferous types undoubted indications of anatomical and other features
which in succeeding ages became the marks of Gleicheniaceae.
Some Carboniferous fronds with short and small pinnules of the
Pecopteris type, bearing sori composed of a small number of sporangia,
have been assigned by Grand’Eury and other authors to the Gleicheniaceae;
the same form of sorus is met with also on fronds with Sphenopteroid
segments. The former is illustrated by Oligocarpia Gutbieri[848] and the
latter by O. Brongniarti described by Stur and by Zeiller[849]. Zeiller has
described the circular sori of Oligocarpia (fig. 270, B) as consisting of three
is furnished by Saporta[843], who described two Eocene species from France.
Gleicheniaceae.
The application by Goeppert[844] and other earlier writers of the generic
name Gleichenites to examples of Palaeozoic ferns was not justified by any
satisfactory evidence. One of Goeppert’s species, Gleichenites
neuropteroides, is identical with Neuropteris heterophylla[845], a plant now
included in the Pteridosperms.
The resemblance of sporangia and sori, whether preserved as carbonised
impressions or as petrified material, from Carboniferous rocks, to those of
recent species of Gleicheniaceae is in many cases at least the result of
misinterpretation of deceptive appearances. Williamson[846] drew attention to
the Gleichenia-like structure of some sections of sporangia from the English
Coal-Measures, but he did not realise the ease with which sections of
Marattiaceous sporangia in different planes may be mistaken for those of
annulate (leptosporangiate) sporangia. In the regular dichotomous habit of
Carboniferous fronds described as species of Diplothmema (Stur) and
Mariopteris (Zeiller)[847] we have a close correspondence with the leaves of
Gleichenia, but the common occurrence of dichotomous branching among
ferns is sufficient reason for regarding this feature as an untrustworthy
criterion of relationship. It is, however, interesting to find that in addition to
the existence of some Upper Carboniferous ferns with sori like those of
recent Gleichenias, the type of stelar anatomy illustrated by Gleichenia
dicarpa (fig. 237, C, p. 310) and other species is characteristic of the
primary structure of the stem of the Pteridosperm Heterangium. We find in
Carboniferous types undoubted indications of anatomical and other features
which in succeeding ages became the marks of Gleicheniaceae.
Some Carboniferous fronds with short and small pinnules of the
Pecopteris type, bearing sori composed of a small number of sporangia,
have been assigned by Grand’Eury and other authors to the Gleicheniaceae;
the same form of sorus is met with also on fronds with Sphenopteroid
segments. The former is illustrated by Oligocarpia Gutbieri[848] and the
latter by O. Brongniarti described by Stur and by Zeiller[849]. Zeiller has
described the circular sori of Oligocarpia (fig. 270, B) as consisting of three
Page 391
to ten pyriform sporangia borne at the ends of lateral veins and possessing a
complete transverse annulus, but Stur[850] believes that the annulus-like
appearance is due to the manner of preservation of exannulate sporangia. In
this opinion Stur is supported by Solms-Laubach[851] and by Schenk[852].
Despite an agreement between Oligocarpia and Gleichenia, as regards the
form of the sori and the number of sporangia, it is not certain that the
existence of a typical Gleicheniaceous annulus has been proved to occur in
any Palaeozoic sporangia[853].
From Upper Triassic beds of Virginia, Fontaine has figured several
fronds for which he instituted the genus Mertensides[854]. The habit, as he
points out, is not dichotomous, but the sori are circular and are said to be
composed in some species of four to six sporangia. No satisfactory
evidence is brought forward in support of the use of a designation implying
a close relationship with recent Gleichenias (sect. Mertensia). One of the
species described by Fontaine was originally named by Bunbury Pecopteris
bullatus[855], the imperfect type-specimen of which is now in the Museum of
the Cambridge Botany School. In the form of the frond, the thick rachis,
and in the pinnules this Triassic species resembles Todites Williamsoni, but
the resemblance does not extend to the sori. Two of Fontaine’s species are
recorded by Stur from Austria[856], but he places them in the genus
Oligocarpia and includes them in the Marattiaceae.
Leuthardt[857] figures what appears to be a Gleicheniaceous fern from the
Upper Triassic beds of Basel as Gleichenites gracilis (Heer) showing sori
composed of five sporangia (fig. 265, C) with a horizontal annulus. A
Rhaetic species Gleichenites microphyllus Schenk[858] from Franconia
agrees in the form of its small rounded pinnules with Gleichenia, but no
sporangia have so far been found.
An impression of a frond from Jurassic rocks of northern Italy figured by
Zigno as Gleichenites elegans[859] closely resembles in habit recent species
of Gleichenia; though no sporangia have been found, the habit of the frond
gives probability to Zigno’s determination.
A Jurassic species from Poland, Gleichenites Rostafinskii, referred by
Raciborski[860] to Gleichenia, exhibits a close agreement in habit and in the
form of the soral impressions to some recent species of Gleichenia.
complete transverse annulus, but Stur[850] believes that the annulus-like
appearance is due to the manner of preservation of exannulate sporangia. In
this opinion Stur is supported by Solms-Laubach[851] and by Schenk[852].
Despite an agreement between Oligocarpia and Gleichenia, as regards the
form of the sori and the number of sporangia, it is not certain that the
existence of a typical Gleicheniaceous annulus has been proved to occur in
any Palaeozoic sporangia[853].
From Upper Triassic beds of Virginia, Fontaine has figured several
fronds for which he instituted the genus Mertensides[854]. The habit, as he
points out, is not dichotomous, but the sori are circular and are said to be
composed in some species of four to six sporangia. No satisfactory
evidence is brought forward in support of the use of a designation implying
a close relationship with recent Gleichenias (sect. Mertensia). One of the
species described by Fontaine was originally named by Bunbury Pecopteris
bullatus[855], the imperfect type-specimen of which is now in the Museum of
the Cambridge Botany School. In the form of the frond, the thick rachis,
and in the pinnules this Triassic species resembles Todites Williamsoni, but
the resemblance does not extend to the sori. Two of Fontaine’s species are
recorded by Stur from Austria[856], but he places them in the genus
Oligocarpia and includes them in the Marattiaceae.
Leuthardt[857] figures what appears to be a Gleicheniaceous fern from the
Upper Triassic beds of Basel as Gleichenites gracilis (Heer) showing sori
composed of five sporangia (fig. 265, C) with a horizontal annulus. A
Rhaetic species Gleichenites microphyllus Schenk[858] from Franconia
agrees in the form of its small rounded pinnules with Gleichenia, but no
sporangia have so far been found.
An impression of a frond from Jurassic rocks of northern Italy figured by
Zigno as Gleichenites elegans[859] closely resembles in habit recent species
of Gleichenia; though no sporangia have been found, the habit of the frond
gives probability to Zigno’s determination.
A Jurassic species from Poland, Gleichenites Rostafinskii, referred by
Raciborski[860] to Gleichenia, exhibits a close agreement in habit and in the
form of the soral impressions to some recent species of Gleichenia.
Page 392
As we pass upwards to Wealden and more recent rocks it becomes clear
that the Gleicheniaceae were prominent members of late Mesozoic floras in
north Europe and reached as far north as Disco Island. In English Wealden
beds portions of sterile fronds have been found which were assigned to a
new genus Leckenbya[861], but it is probable that these specimens would be
more correctly referred to Gleichenites. Similarly fragments of Gleichenia-
like pinnae with very small rounded pinnules occur in the Wealden rocks of
Bernissart, Belgium[862], in north Germany[863], and elsewhere. Conclusive
evidence has been obtained by Prof. Bommer of the existence of
Gleichenites in Wealden beds near Brussels, where many plant remains
have been found in a wonderful state of preservation. The specimens, which
I had an opportunity of seeing some years ago, might easily be mistaken for
rather old and brown pieces of recent plants. Some of the Belgian
fragments, of which Prof. Bommer has kindly sent me drawings and
photographs, are characterised by an arrangement of vascular tissue
identical with that in the petioles and rhizomes of some protostelic
Gleichenias. The stele of one of the Belgian rhizomes appears to be
identical with that of Gleichenia dicarpa (fig. 237, C. p. 310).
that the Gleicheniaceae were prominent members of late Mesozoic floras in
north Europe and reached as far north as Disco Island. In English Wealden
beds portions of sterile fronds have been found which were assigned to a
new genus Leckenbya[861], but it is probable that these specimens would be
more correctly referred to Gleichenites. Similarly fragments of Gleichenia-
like pinnae with very small rounded pinnules occur in the Wealden rocks of
Bernissart, Belgium[862], in north Germany[863], and elsewhere. Conclusive
evidence has been obtained by Prof. Bommer of the existence of
Gleichenites in Wealden beds near Brussels, where many plant remains
have been found in a wonderful state of preservation. The specimens, which
I had an opportunity of seeing some years ago, might easily be mistaken for
rather old and brown pieces of recent plants. Some of the Belgian
fragments, of which Prof. Bommer has kindly sent me drawings and
photographs, are characterised by an arrangement of vascular tissue
identical with that in the petioles and rhizomes of some protostelic
Gleichenias. The stele of one of the Belgian rhizomes appears to be
identical with that of Gleichenia dicarpa (fig. 237, C. p. 310).
Page 393
Fig. 262.
A. Gleichenites longipennis Heer.
B. G. delicatula Heer.
C. G. Nordenskioldi Heer.
D. G. Zippei. (Corda.)
(After Heer; A, B, D, very slightly reduced.)
Gleichenites Zippei (Corda). Fig. 262, D.
This species, originally described by Corda as Pecopteris Zippei[864] and
afterwards figured by Heer[865] as Gleichenia Zippei (fig. 262, D) from
Urgonian rocks of Greenland, affords a striking example of a Mesozoic
A. Gleichenites longipennis Heer.
B. G. delicatula Heer.
C. G. Nordenskioldi Heer.
D. G. Zippei. (Corda.)
(After Heer; A, B, D, very slightly reduced.)
Gleichenites Zippei (Corda). Fig. 262, D.
This species, originally described by Corda as Pecopteris Zippei[864] and
afterwards figured by Heer[865] as Gleichenia Zippei (fig. 262, D) from
Urgonian rocks of Greenland, affords a striking example of a Mesozoic
Page 394
member of the Gleicheniaceae. It is characterised by the dichotomous
branching of the frond and by the occurrence of arrested buds in the forks.
The long and slender pinnae, reaching a length of 9 cm. and a breadth of 6–
8 mm., bear small crowded pinnules occasionally with circular sori which
are described by Heer as consisting of a small number of sporangia (cf. fig.
262, C). Several other Lower Cretaceous species are recorded by Heer from
Greenland, some of which are probably unnecessarily separated from
Gleichenites Zippei. Examples of these are represented in fig. 262, A, B, C.
A Gleicheniaceous species described by Debey and Ettingshausen from
Lower Cretaceous rocks of Aix-la-Chapelle as Didymosorus
comptonifolius[866] is very similar in habit to some of Heer’s Greenland
species: this should probably be referred to the genus Gleichenites.
Gleichenites hantonensis, Wank. Fig. 263.
From the Eocene beds of Bournemouth, Gardner and Ettingshausen[867]
have described under the name Gleichenia hantonensis what is in all
probability a true Gleichenia (fig. 263). This species, originally recorded by
Wanklyn[868], is characterised by a slender forked rachis showing what may
be traces of arrested buds between the arms of the branches, by circular sori
of six or eight sporangia and by the presence of peculiar tendril-like
appendages on the pinnae. If the description of the tendrils is correct, this
British species affords one of the few instances of ferns adapted for
climbing and may be compared with the recent species Davallia aculeata
(fig. 232, p. 299).
Matonineae.
The genera Laccopteris and Matonidium may be described as examples
of Mesozoic ferns exhibiting a very close agreement with Matonia.
Laccopteris. This genus, founded by Presl[869], may be described as
follows:—
Frond pedate, in habit resembling Matonia pectinata, with pinnate or pinnatifid pinnae;
ultimate segments linear, provided with a well-marked midrib giving off numerous
dichotomously branched secondary veins which are in places connected by lateral anastomoses.
Sori circular, forming a single row on each side of the midrib (fig. 278, B); sporangia 5–15 in
each sorus, with an oblique annulus and tetrahedral spores. The presence of an indusium is not
certainly established.
branching of the frond and by the occurrence of arrested buds in the forks.
The long and slender pinnae, reaching a length of 9 cm. and a breadth of 6–
8 mm., bear small crowded pinnules occasionally with circular sori which
are described by Heer as consisting of a small number of sporangia (cf. fig.
262, C). Several other Lower Cretaceous species are recorded by Heer from
Greenland, some of which are probably unnecessarily separated from
Gleichenites Zippei. Examples of these are represented in fig. 262, A, B, C.
A Gleicheniaceous species described by Debey and Ettingshausen from
Lower Cretaceous rocks of Aix-la-Chapelle as Didymosorus
comptonifolius[866] is very similar in habit to some of Heer’s Greenland
species: this should probably be referred to the genus Gleichenites.
Gleichenites hantonensis, Wank. Fig. 263.
From the Eocene beds of Bournemouth, Gardner and Ettingshausen[867]
have described under the name Gleichenia hantonensis what is in all
probability a true Gleichenia (fig. 263). This species, originally recorded by
Wanklyn[868], is characterised by a slender forked rachis showing what may
be traces of arrested buds between the arms of the branches, by circular sori
of six or eight sporangia and by the presence of peculiar tendril-like
appendages on the pinnae. If the description of the tendrils is correct, this
British species affords one of the few instances of ferns adapted for
climbing and may be compared with the recent species Davallia aculeata
(fig. 232, p. 299).
Matonineae.
The genera Laccopteris and Matonidium may be described as examples
of Mesozoic ferns exhibiting a very close agreement with Matonia.
Laccopteris. This genus, founded by Presl[869], may be described as
follows:—
Frond pedate, in habit resembling Matonia pectinata, with pinnate or pinnatifid pinnae;
ultimate segments linear, provided with a well-marked midrib giving off numerous
dichotomously branched secondary veins which are in places connected by lateral anastomoses.
Sori circular, forming a single row on each side of the midrib (fig. 278, B); sporangia 5–15 in
each sorus, with an oblique annulus and tetrahedral spores. The presence of an indusium is not
certainly established.
Page 395
Fig. 263. Gleichenites hantonensis Wank. (Restoration, after Gardner and Ettingshausen.)
Schenk[870], who described several specimens of Laccopteris from
Rhaetic rocks of Germany, compared the genus with Gleichenia but he also
recognised the close resemblance to Matonia pectinata. Zeiller[871] first
established the practical identity of the sori and sporangia of Laccopteris
and Matonia. The Rhaetic species, such as L. Muensteri, L. elegans, and L.
Goepperti, agree very closely with L. polypodioides and need not be
described in detail.
Schenk[870], who described several specimens of Laccopteris from
Rhaetic rocks of Germany, compared the genus with Gleichenia but he also
recognised the close resemblance to Matonia pectinata. Zeiller[871] first
established the practical identity of the sori and sporangia of Laccopteris
and Matonia. The Rhaetic species, such as L. Muensteri, L. elegans, and L.
Goepperti, agree very closely with L. polypodioides and need not be
described in detail.
Page 396
Fig. 264. Laccopteris elegans (Presl). (From a specimen in the British Museum; from the
Lower Keuper of Bayreuth, Germany. Nat. size; part of pinnule × 3.)
The Rhaetic species Laccopteris elegans, represented in fig. 264,
illustrates the characteristic habit of the genus and shows a feature usually
overlooked[872], namely the occurrence of anastomoses between the lateral
veins. The form of the sorus of another Rhaetic species is shown in fig. 265,
E. Schenk figures an interesting series of fronds of L. Goepperti in different
stages of growth[873]; one of the younger leaves is seen in fig. 265, D. An
examination of Rhaetic specimens of Laccopteris in the Bergakademie of
Berlin convinced me of the correctness of the published descriptions of the
sori.
Lower Keuper of Bayreuth, Germany. Nat. size; part of pinnule × 3.)
The Rhaetic species Laccopteris elegans, represented in fig. 264,
illustrates the characteristic habit of the genus and shows a feature usually
overlooked[872], namely the occurrence of anastomoses between the lateral
veins. The form of the sorus of another Rhaetic species is shown in fig. 265,
E. Schenk figures an interesting series of fronds of L. Goepperti in different
stages of growth[873]; one of the younger leaves is seen in fig. 265, D. An
examination of Rhaetic specimens of Laccopteris in the Bergakademie of
Berlin convinced me of the correctness of the published descriptions of the
sori.
Page 397
Fig. 265.
A. Matonidium Wiesneri. (Slightly enlarged.)
B. Marattiopsis marantacea. (Slightly enlarged.)
C. Gleichenites gracilis. (Slightly enlarged.)
D. Laccopteris Goepperti. (Slightly reduced.)
E. L. Muensteri. (Enlarged.)
(A, after Krasser; B, C, after Leuthardt; D, E, after Schenk.)
Laccopteris polypodioides (Brongniart). Figs. 266–268; 278, A.
Phlebopteris polypodioides[874], Brongniart, Hist. vég. foss. p. 372,
1828.
Pl. lxxxiii. fig. 1.
— P. propinqua, ibid. Pls. cxxxii. fig. 1, cxxxiii. fig. 2.
1829. Pecopteris caespitosa, Phillips, Geol. Yorks. p. 148, Pl. viii. fig. 10.
— P. crenifolia, ibid. Pl. viii. fig. 10.
A. Matonidium Wiesneri. (Slightly enlarged.)
B. Marattiopsis marantacea. (Slightly enlarged.)
C. Gleichenites gracilis. (Slightly enlarged.)
D. Laccopteris Goepperti. (Slightly reduced.)
E. L. Muensteri. (Enlarged.)
(A, after Krasser; B, C, after Leuthardt; D, E, after Schenk.)
Laccopteris polypodioides (Brongniart). Figs. 266–268; 278, A.
Phlebopteris polypodioides[874], Brongniart, Hist. vég. foss. p. 372,
1828.
Pl. lxxxiii. fig. 1.
— P. propinqua, ibid. Pls. cxxxii. fig. 1, cxxxiii. fig. 2.
1829. Pecopteris caespitosa, Phillips, Geol. Yorks. p. 148, Pl. viii. fig. 10.
— P. crenifolia, ibid. Pl. viii. fig. 10.
Page 398
— P. ligata, ibid. Pl. viii. fig. 14.
Fig. 266. Laccopteris polypodioides (Brongn.). (× 14.) (Brit. Mus.)
In habit this species closely resembles Matonia and Matonidium, the long
petiole divides distally into several spreading pinnatifid pinnae with linear
ultimate segments (fig. 278, A). Circular sori (indusiate?) occur in a single
row on each side of the midrib containing 12–14 large sporangia (fig. 266)
characterised by an obliquely vertical annulus. The midrib of the pinnules
gives off secondary veins at a wide angle and these form a series of
elongated meshes parallel to the median rib, as in the recent genus
Woodwardia; forked and anastomosing branches are given off from these to
the edge of the lamina (fig. 267).
Fig. 266. Laccopteris polypodioides (Brongn.). (× 14.) (Brit. Mus.)
In habit this species closely resembles Matonia and Matonidium, the long
petiole divides distally into several spreading pinnatifid pinnae with linear
ultimate segments (fig. 278, A). Circular sori (indusiate?) occur in a single
row on each side of the midrib containing 12–14 large sporangia (fig. 266)
characterised by an obliquely vertical annulus. The midrib of the pinnules
gives off secondary veins at a wide angle and these form a series of
elongated meshes parallel to the median rib, as in the recent genus
Woodwardia; forked and anastomosing branches are given off from these to
the edge of the lamina (fig. 267).
Page 399
Fig. 267. Pinnules of Laccopteris. (Enlarged.)
A, B. From the Inferior Oolite of Yorkshire.
C. From the Inferior Oolite of Stamford. (British Museum.)
The specimen shown in fig. 268 is probably a young frond of this
species.
A very similar, possibly a specifically identical plant, was described by
Leckenby from English Jurassic rocks as Phlebopteris Woodwardi[875], the
distinguishing features of which are the greater number of lateral veins and
the smaller sori (fig. 267, A).
The name Microdictyon was proposed by Saporta[876] for pinnules
differing slightly from those of Laccopteris in venation characters: he
included Laccopteris Woodwardi in this genus, but such differences as are
recognisable in the venation hardly justify the use of a distinct generic title.
Similarly, specimens described by Debey and Ettingshausen[877] from Lower
Cretaceous rocks of Aix-la-Chapelle as species of Carolopteris may also be
included in Laccopteris.
A, B. From the Inferior Oolite of Yorkshire.
C. From the Inferior Oolite of Stamford. (British Museum.)
The specimen shown in fig. 268 is probably a young frond of this
species.
A very similar, possibly a specifically identical plant, was described by
Leckenby from English Jurassic rocks as Phlebopteris Woodwardi[875], the
distinguishing features of which are the greater number of lateral veins and
the smaller sori (fig. 267, A).
The name Microdictyon was proposed by Saporta[876] for pinnules
differing slightly from those of Laccopteris in venation characters: he
included Laccopteris Woodwardi in this genus, but such differences as are
recognisable in the venation hardly justify the use of a distinct generic title.
Similarly, specimens described by Debey and Ettingshausen[877] from Lower
Cretaceous rocks of Aix-la-Chapelle as species of Carolopteris may also be
included in Laccopteris.
Page 400
Fig. 268. ? Laccopteris polypodioides. Nat. size. From a specimen in the Whitby Museum
(Brit. Mus.).
Laccopteris Dunkeri (Schenk)[878].
This species is represented in several Wealden localities by fragments of
fertile pinnae similar to those of L. polypodioides. It is almost impossible to
distinguish small specimens of the Wealden fern from Heer’s genus
Nathorstia (Marattiaceae) unless the sori are well preserved. This species
occurs in Wealden beds in England, Germany, Belgium, and elsewhere and
has been discovered by Dr Marcus Gunn in Upper Jurassic plant-beds of
Sutherlandshire (N.E. Scotland).
• • • • •
Laccopteris is widely spread in Rhaetic, Jurassic and Lower Cretaceous
floras. It affords evidence of the former abundance in northern latitudes of a
(Brit. Mus.).
Laccopteris Dunkeri (Schenk)[878].
This species is represented in several Wealden localities by fragments of
fertile pinnae similar to those of L. polypodioides. It is almost impossible to
distinguish small specimens of the Wealden fern from Heer’s genus
Nathorstia (Marattiaceae) unless the sori are well preserved. This species
occurs in Wealden beds in England, Germany, Belgium, and elsewhere and
has been discovered by Dr Marcus Gunn in Upper Jurassic plant-beds of
Sutherlandshire (N.E. Scotland).
• • • • •
Laccopteris is widely spread in Rhaetic, Jurassic and Lower Cretaceous
floras. It affords evidence of the former abundance in northern latitudes of a
Page 401
family now represented by the two species of Matonia confined to a
restricted area in the southern hemisphere.
Matonidium.
Schenk[879] instituted this convenient term for fossil fern fronds agreeing
in habit and in their sori with Matonia pectinata (figs. 227, 228, p. 292).
Zeiller[880] has drawn attention to the fact that the Mesozoic species differ
from the surviving types in the greater number of sporangia in each sorus,
and, it may be added, in Matonidium the fertile pinnules are more richly
supplied with sori than are those of Matonia. Unfortunately our knowledge
of the structure of the sporangia of Matonidium is less complete than in the
case of Laccopteris, but such evidence as is available justifies the
conclusion that Matonia is a direct descendant of ferns which formed a
prominent feature in European Jurassic and Wealden floras. It is interesting
to find that in a Cretaceous species, described by Krasser (fig. 265, A) since
the publication of Zeiller’s paper, the sori appear to be identical in
distribution and in appearance with those of the recent species.
I am indebted to Prof. Bommer for permission to reproduce the
unpublished drawing represented in fig. 237 D (p. 310) of a section of the
rhizome of Matonidium from the Belgian Wealden beds of Hainaut (“Flore
Bernissartienne”). The section shows an arrangement of vascular tissue
identical with that in the recent species: there may be two solenosteles and
in addition a solid axial strand. The form of the leaf-trace in the fossil
appears to be identical with that in Matonia pectinata (fig. 237, A, p. 310).
Matonidium Goepperti (Ettingshausen)[881]. Fig. 269.
Under this name are included specimens from Inferior Oolite and
Wealden strata in Britain and elsewhere. It is, however, not impossible that
if more information were available, we should find adequate reasons for
recognising two specific types. Fontaine[882], adhering rigidly to the rules of
priority, speaks of this species as Matonidium Althausii (Dunker), but
Ettingshausen’s specific term is better known.
restricted area in the southern hemisphere.
Matonidium.
Schenk[879] instituted this convenient term for fossil fern fronds agreeing
in habit and in their sori with Matonia pectinata (figs. 227, 228, p. 292).
Zeiller[880] has drawn attention to the fact that the Mesozoic species differ
from the surviving types in the greater number of sporangia in each sorus,
and, it may be added, in Matonidium the fertile pinnules are more richly
supplied with sori than are those of Matonia. Unfortunately our knowledge
of the structure of the sporangia of Matonidium is less complete than in the
case of Laccopteris, but such evidence as is available justifies the
conclusion that Matonia is a direct descendant of ferns which formed a
prominent feature in European Jurassic and Wealden floras. It is interesting
to find that in a Cretaceous species, described by Krasser (fig. 265, A) since
the publication of Zeiller’s paper, the sori appear to be identical in
distribution and in appearance with those of the recent species.
I am indebted to Prof. Bommer for permission to reproduce the
unpublished drawing represented in fig. 237 D (p. 310) of a section of the
rhizome of Matonidium from the Belgian Wealden beds of Hainaut (“Flore
Bernissartienne”). The section shows an arrangement of vascular tissue
identical with that in the recent species: there may be two solenosteles and
in addition a solid axial strand. The form of the leaf-trace in the fossil
appears to be identical with that in Matonia pectinata (fig. 237, A, p. 310).
Matonidium Goepperti (Ettingshausen)[881]. Fig. 269.
Under this name are included specimens from Inferior Oolite and
Wealden strata in Britain and elsewhere. It is, however, not impossible that
if more information were available, we should find adequate reasons for
recognising two specific types. Fontaine[882], adhering rigidly to the rules of
priority, speaks of this species as Matonidium Althausii (Dunker), but
Ettingshausen’s specific term is better known.
Page 402
Fig. 269. Matonidium Goepperti (Ettings.). (A, B, ½ nat. size; C, approximately nat. size.)
Fronds pedate and apparently identical in habit with those of Matonia pectinata; ultimate
segments linear, slightly falcate and bluntly pointed. Sori circular or oval, numerous, containing
15 to 20 sporangia with an oblique annulus, in two rows on the lower surface of the pinnules;
indusium as in Matonia.
The English examples have so far afforded no information in regard to
sporangial structure, but Schenk[883] has recognised a distinct annulus in
German material. In his description of fossil plants from Lower Cretaceous
rocks in California, Fontaine[884] doubtfully identifies two very small
fragments as Matonidium Althausii; the evidence is, however, wholly
inadequate.
Matonidium Wiesneri, Krasser[885]. Fig. 265, A.
This Cenomanian (Cretaceous) species from Moravia appears to be
identical in habit with the older type. The pinnules are larger and bear fewer
Fronds pedate and apparently identical in habit with those of Matonia pectinata; ultimate
segments linear, slightly falcate and bluntly pointed. Sori circular or oval, numerous, containing
15 to 20 sporangia with an oblique annulus, in two rows on the lower surface of the pinnules;
indusium as in Matonia.
The English examples have so far afforded no information in regard to
sporangial structure, but Schenk[883] has recognised a distinct annulus in
German material. In his description of fossil plants from Lower Cretaceous
rocks in California, Fontaine[884] doubtfully identifies two very small
fragments as Matonidium Althausii; the evidence is, however, wholly
inadequate.
Matonidium Wiesneri, Krasser[885]. Fig. 265, A.
This Cenomanian (Cretaceous) species from Moravia appears to be
identical in habit with the older type. The pinnules are larger and bear fewer
Page 403
sori. Krasser’s figures of the sterile pinnules show no lateral anastomosing
between the secondary veins, but the small vascular network below each
sorus (fig. 265, A) is identical with that in Matonia pectinata. The indusiate
sori contain about six sporangia with an oblique annulus.
The very wide geographical distribution of the Matonineae during the
Mesozoic era affords a striking contrast to the limited range of the Malayan
survivals.
Hymenophyllaceae.
The frequent use of the generic name Hymenophyllites as a designation
of Palaeozoic ferns, more particularly in the older literature, is another
instance of the undue importance which palaeobotanists have always been
prone to attach to external resemblances of vegetative organs. The fragment
of lamina described by Stur for the Culm Measures of Austria as
Hymenophyllum waldenburgense[886] has no claim to consideration as
evidence of Palaeozoic Hymenophyllaceae. On the other hand, there are a
few records of fertile fronds which, though not to be accepted without
reserve, are worthy of more careful examination. Some petrified sporangia
described by Renault[887] from the Culm of Esnost are referred to
Hymenophyllites on account of the position of the annulus, which appears
to encircle about two-thirds of the circumference; it is, however, not certain
that the annulus is horizontal as in the recent genus.
The Culm species Rhodea patentissima described by Ettingshausen[888] as
Hymenophyllites patentissima and subsequently referred by Stur[889] to
Rhodea, is regarded by these authors as closely allied to Hymenophyllum
simply on the ground of the finely divided and delicate sterile fronds;
another species, Rhodea moravica (Ett.), which Ettingshausen referred to
Trichomanes, is compared with recent species of that genus. In neither case
do we know anything of sporangial characters.
between the secondary veins, but the small vascular network below each
sorus (fig. 265, A) is identical with that in Matonia pectinata. The indusiate
sori contain about six sporangia with an oblique annulus.
The very wide geographical distribution of the Matonineae during the
Mesozoic era affords a striking contrast to the limited range of the Malayan
survivals.
Hymenophyllaceae.
The frequent use of the generic name Hymenophyllites as a designation
of Palaeozoic ferns, more particularly in the older literature, is another
instance of the undue importance which palaeobotanists have always been
prone to attach to external resemblances of vegetative organs. The fragment
of lamina described by Stur for the Culm Measures of Austria as
Hymenophyllum waldenburgense[886] has no claim to consideration as
evidence of Palaeozoic Hymenophyllaceae. On the other hand, there are a
few records of fertile fronds which, though not to be accepted without
reserve, are worthy of more careful examination. Some petrified sporangia
described by Renault[887] from the Culm of Esnost are referred to
Hymenophyllites on account of the position of the annulus, which appears
to encircle about two-thirds of the circumference; it is, however, not certain
that the annulus is horizontal as in the recent genus.
The Culm species Rhodea patentissima described by Ettingshausen[888] as
Hymenophyllites patentissima and subsequently referred by Stur[889] to
Rhodea, is regarded by these authors as closely allied to Hymenophyllum
simply on the ground of the finely divided and delicate sterile fronds;
another species, Rhodea moravica (Ett.), which Ettingshausen referred to
Trichomanes, is compared with recent species of that genus. In neither case
do we know anything of sporangial characters.
Page 404
Fig. 270.
A, E. Senftenbergia elegans.
B. Oligocarpia Brongniartii.
C. Trichomanes sp.
D. Hymenophyllum tunbrigense.
F, G. Sphenopteris (Hymenophyllites) quadridactylites.
(A, B, F, G, after Zeiller; D, after Hooker; E, after Stur.)
A fertile sphenopteroid frond figured by Schimper as Hymenophyllum
Weissi[890] from the Coal-Measures of Saarbrücken bears some resemblance
to recent Hymenophyllaceae, but the figures are by no means convincing:
an examination of the type-specimens in the Strassburg Museum led Solms-
Laubach[891] to express dissent from Schimper’s determination. A more
satisfactory example is that afforded by the fertile pieces of a frond
described by Zeiller[892] from French Coal-Measures as Hymenophyllites
quadridactylites (Gutbier). Some of the ultimate segments with a truncated
tip are preserved in close association with a group of oval sporangia with a
complete transverse annulus (fig. 270, F, G). The position of the sporangia
is such as to suggest their separation from a terminal columnar receptacle
like that in Trichomanes and Hymenophyllum. In his account of this species
from the Coal-Measures of the Forest of Wyre, Kidston[893] states that
Zeiller informed him that he had noticed traces of what appeared to be a
columnar receptacle in the French specimens.
A, E. Senftenbergia elegans.
B. Oligocarpia Brongniartii.
C. Trichomanes sp.
D. Hymenophyllum tunbrigense.
F, G. Sphenopteris (Hymenophyllites) quadridactylites.
(A, B, F, G, after Zeiller; D, after Hooker; E, after Stur.)
A fertile sphenopteroid frond figured by Schimper as Hymenophyllum
Weissi[890] from the Coal-Measures of Saarbrücken bears some resemblance
to recent Hymenophyllaceae, but the figures are by no means convincing:
an examination of the type-specimens in the Strassburg Museum led Solms-
Laubach[891] to express dissent from Schimper’s determination. A more
satisfactory example is that afforded by the fertile pieces of a frond
described by Zeiller[892] from French Coal-Measures as Hymenophyllites
quadridactylites (Gutbier). Some of the ultimate segments with a truncated
tip are preserved in close association with a group of oval sporangia with a
complete transverse annulus (fig. 270, F, G). The position of the sporangia
is such as to suggest their separation from a terminal columnar receptacle
like that in Trichomanes and Hymenophyllum. In his account of this species
from the Coal-Measures of the Forest of Wyre, Kidston[893] states that
Zeiller informed him that he had noticed traces of what appeared to be a
columnar receptacle in the French specimens.
Page 405
The records of Hymenophyllaceae from the Mesozoic and Tertiary
formations are not such as need detain us. The facts bearing on the
geological history of this family are singularly meagre. There is no evidence
which can be adduced in favour of regarding the Hymenophyllaceae as
ferns of great antiquity, which played a prominent part in the floras of the
past.
It is interesting to find that the genus Ankyropteris[894], one of the
Botryopterideae (a group of Palaeozoic Ferns for which I propose the name
Coenopterideae), has a morphological character in common with
Trichomanes, namely the production of axillary buds: there are also features
in the stelar anatomy shared by the Botryopterideae and
Hymenophyllaceae[895]. These resemblances, though by no means
amounting to proof of near relationship, point to a remote ancestry for
certain features retained by existing members of the Hymenophyllaceae.
Cyatheaceae.
The specimens from the Culm rocks of Moravia on which Stur founded
the species Thyrsopteris schistorum[896] are too imperfectly preserved to
warrant the use of this generic name. Goeppert[897] in 1836 instituted the
genera Cyatheites, Hemitelites, and Balantites for species of Carboniferous
ferns believed to be closely allied to recent Cyatheaceae, but a fuller
knowledge of these types has clearly demonstrated that in all cases the
reference to this family had no justification.
The Upper Carboniferous species Dicksonites Pluckeneti, of which
Sterzel[898] described fertile specimens in 1886 as possessing circular sori,
has since been shown by Grand’Eury[899] to be a Pteridosperm bearing small
seeds. In Sphenopteris (Discopteris) cristata (Brongn.) Zeiller[900] has
described sori very like those of Cyathea and Alsophila, but differing in the
exannulate sporangia: this species, like so many of the Palaeozoic ferns, is
probably more akin to the Marattiaceae than to the Cyatheaceae.
We have as yet no satisfactory evidence of the existence of the
Cyatheaceae in Palaeozoic floras. It is not until we reach the Jurassic period
that trustworthy data are obtained. Raciborski[901] has identified as
Cyatheaceous fertile Jurassic fronds from Poland, but his figures are
inconclusive. In Alsophila polonica it is not clear whether the annulus is
formations are not such as need detain us. The facts bearing on the
geological history of this family are singularly meagre. There is no evidence
which can be adduced in favour of regarding the Hymenophyllaceae as
ferns of great antiquity, which played a prominent part in the floras of the
past.
It is interesting to find that the genus Ankyropteris[894], one of the
Botryopterideae (a group of Palaeozoic Ferns for which I propose the name
Coenopterideae), has a morphological character in common with
Trichomanes, namely the production of axillary buds: there are also features
in the stelar anatomy shared by the Botryopterideae and
Hymenophyllaceae[895]. These resemblances, though by no means
amounting to proof of near relationship, point to a remote ancestry for
certain features retained by existing members of the Hymenophyllaceae.
Cyatheaceae.
The specimens from the Culm rocks of Moravia on which Stur founded
the species Thyrsopteris schistorum[896] are too imperfectly preserved to
warrant the use of this generic name. Goeppert[897] in 1836 instituted the
genera Cyatheites, Hemitelites, and Balantites for species of Carboniferous
ferns believed to be closely allied to recent Cyatheaceae, but a fuller
knowledge of these types has clearly demonstrated that in all cases the
reference to this family had no justification.
The Upper Carboniferous species Dicksonites Pluckeneti, of which
Sterzel[898] described fertile specimens in 1886 as possessing circular sori,
has since been shown by Grand’Eury[899] to be a Pteridosperm bearing small
seeds. In Sphenopteris (Discopteris) cristata (Brongn.) Zeiller[900] has
described sori very like those of Cyathea and Alsophila, but differing in the
exannulate sporangia: this species, like so many of the Palaeozoic ferns, is
probably more akin to the Marattiaceae than to the Cyatheaceae.
We have as yet no satisfactory evidence of the existence of the
Cyatheaceae in Palaeozoic floras. It is not until we reach the Jurassic period
that trustworthy data are obtained. Raciborski[901] has identified as
Cyatheaceous fertile Jurassic fronds from Poland, but his figures are
inconclusive. In Alsophila polonica it is not clear whether the annulus is
Page 406
vertical or oblique, and in another supposed member of the family,
Gonatosorus Nathorsti, in which the indusium is described as bivalvate,
there is no proof of affinity to Cyatheaceae.
In attempting to decipher the past history of the Cyatheaceae it is
important to remember the close resemblance between the fertile segments
of some species of Davallia (Polypodiaceae) and those of Dicksonia (fig.
229, C, D, p. 294). Unless the sporangia are well enough preserved to show
the position of the annulus, it is frequently impossible to feel much
confidence in the value of the grosser features, such as the reduced lamina
of the fertile segments and the form of the sori. It is, however, probable that
the widely-spread Jurassic species Coniopteris hymenophylloides is
correctly referred to the Cyatheaceae, but even in the case of this species
the evidence of external form needs confirmation by an examination of
individual sporangia.
Coniopteris.
This genus was instituted by Brongniart[902] for fossil fronds characterised
by pinnules more or less intermediate between the Pecopteris and
Sphenopteris type and agreeing in the form of the sori with the leaves of
recent species of Dicksonia. It should be noted that Stur included in this
genus a species, Coniopteris lunzensis[903] from the Upper Trias of Lunz,
which he regarded as a Marattiaceous fern.
Coniopteris hymenophylloides, Brongn. Figs. 271, 272, 275, B.
Sphenopteris hymenophylloides, Brongniart, Hist. vég. foss. p. 189,
1828.
Pl. lvi. fig. 4.
1829. S. stipata, Phillips, Geol. York. p. 147, Pl. x. fig. 8.
1835. Tympanophora simplex, Lindley and Hutton, Foss. Flor. Pl. clxx. A.
— T. racemosa, ibid. Pl. clxx. B.
— Sphenopteris arguta, ibid. Pl. clxviii.
1836. Hymenophyllites Phillipsi, Goeppert, Foss. Farn. p. 256.
1849. Coniopteris hymenophylloides, Brongniart, Tableau, p. 105.
— Coniopteris Murrayana, ibid.
Gonatosorus Nathorsti, in which the indusium is described as bivalvate,
there is no proof of affinity to Cyatheaceae.
In attempting to decipher the past history of the Cyatheaceae it is
important to remember the close resemblance between the fertile segments
of some species of Davallia (Polypodiaceae) and those of Dicksonia (fig.
229, C, D, p. 294). Unless the sporangia are well enough preserved to show
the position of the annulus, it is frequently impossible to feel much
confidence in the value of the grosser features, such as the reduced lamina
of the fertile segments and the form of the sori. It is, however, probable that
the widely-spread Jurassic species Coniopteris hymenophylloides is
correctly referred to the Cyatheaceae, but even in the case of this species
the evidence of external form needs confirmation by an examination of
individual sporangia.
Coniopteris.
This genus was instituted by Brongniart[902] for fossil fronds characterised
by pinnules more or less intermediate between the Pecopteris and
Sphenopteris type and agreeing in the form of the sori with the leaves of
recent species of Dicksonia. It should be noted that Stur included in this
genus a species, Coniopteris lunzensis[903] from the Upper Trias of Lunz,
which he regarded as a Marattiaceous fern.
Coniopteris hymenophylloides, Brongn. Figs. 271, 272, 275, B.
Sphenopteris hymenophylloides, Brongniart, Hist. vég. foss. p. 189,
1828.
Pl. lvi. fig. 4.
1829. S. stipata, Phillips, Geol. York. p. 147, Pl. x. fig. 8.
1835. Tympanophora simplex, Lindley and Hutton, Foss. Flor. Pl. clxx. A.
— T. racemosa, ibid. Pl. clxx. B.
— Sphenopteris arguta, ibid. Pl. clxviii.
1836. Hymenophyllites Phillipsi, Goeppert, Foss. Farn. p. 256.
1849. Coniopteris hymenophylloides, Brongniart, Tableau, p. 105.
— Coniopteris Murrayana, ibid.
Page 407
Sphenopteris nephrocarpa, Bunbury, Quart. Journ. Geol. Soc. Vol.
1851.
vii. p. 129, Pl. xii. fig. 1.
Thyrsopteris Murrayana, Heer, Flor. Foss. Arct. Vol. iv. (2) p. 30,
1876.
Pls. i. ii. viii.
The above list represents a small selection of the names applied to
Jurassic ferns from different localities which there are good grounds for
regarding as referable to a single type[904].
Frond tripinnate; pinnae linear acuminate, attached to the rachis at a wide angle; the pinnules
vary considerably in size and shape; in some the lamina is divided into a few broad and rounded
lobes (fig. 275, B) while in others the leaflets are dissected into narrow linear segments. The sori
are borne at the ends of veins; the fertile pinnules have a much reduced lamina and, in extreme
cases, bear a close resemblance to those of Thyrsopteris elegans (fig. 229, A, p. 294). The sori
are partially enclosed in a cup-like indusium and the sporangia appear to have an oblique
annulus.
Venation and habit of frond of the Sphenopteris type.
Fig. 271. Coniopteris hymenophylloides (Brongn.). Nat. size. From a specimen in the
Manchester Museum.
The pinna shown in fig. 271 is the type-specimen of Sphenopteris arguta
Lind. and Hutt. from the Yorkshire Inferior Oolite and is indistinguishable
from the English examples on which Brongniart founded his species S.
1851.
vii. p. 129, Pl. xii. fig. 1.
Thyrsopteris Murrayana, Heer, Flor. Foss. Arct. Vol. iv. (2) p. 30,
1876.
Pls. i. ii. viii.
The above list represents a small selection of the names applied to
Jurassic ferns from different localities which there are good grounds for
regarding as referable to a single type[904].
Frond tripinnate; pinnae linear acuminate, attached to the rachis at a wide angle; the pinnules
vary considerably in size and shape; in some the lamina is divided into a few broad and rounded
lobes (fig. 275, B) while in others the leaflets are dissected into narrow linear segments. The sori
are borne at the ends of veins; the fertile pinnules have a much reduced lamina and, in extreme
cases, bear a close resemblance to those of Thyrsopteris elegans (fig. 229, A, p. 294). The sori
are partially enclosed in a cup-like indusium and the sporangia appear to have an oblique
annulus.
Venation and habit of frond of the Sphenopteris type.
Fig. 271. Coniopteris hymenophylloides (Brongn.). Nat. size. From a specimen in the
Manchester Museum.
The pinna shown in fig. 271 is the type-specimen of Sphenopteris arguta
Lind. and Hutt. from the Yorkshire Inferior Oolite and is indistinguishable
from the English examples on which Brongniart founded his species S.
Page 408
hymenophylloides. Fig. 272 shows a specimen from the York Museum
illustrating the difference between the sterile and fertile pinnae. The
resemblance of some fertile pinnae of Coniopteris hymenophylloides to
those of Thyrsopteris elegans has led to a frequent use, without any solid
justification, of the generic name of the Juan Fernandez fern for Jurassic
and Wealden plants. It is not impossible that some of the fossils described
by Heer from Jurassic rocks of Siberia[905] as species of Thyrsopteris are
Cyatheaceous ferns, but it is impossible to say with certainty that they are
generically identical with the recent species. In his monograph of the
Potomac flora of Virginia[906] and Maryland, Fontaine has described as
species of Thyrsopteris several specimens of fronds which afford no
evidence as to the nature of the sori or sporangia. Some of the fronds
referred by this author to Thyrsopteris rarinervis[907], which I examined in
the Washington Museum, are in all probability examples of Onychiopsis, a
genus included in the Polypodiaceae. The fragments described by Lester
Ward[908] as species of Thyrsopteris from the Lower Cretaceous of the Black
Hills of North America afford no satisfactory evidence of relationship to the
recent type. Similarly Velenovský has described a Lower Cretaceous
Onychiopsis from Bohemia[909] as a species of Thyrsopteris, although the
fertile segments bear little or no resemblance to those of the Cyatheaceous
genus. Some fertile portions of fronds described by Heer[910] as Asplenium
Johnstrupi and afterwards as Dicksonia Johnstrupi[911] from the Cretaceous
beds (Kome series) of Greenland are very similar to Coniopteris
hymenophylloides.
illustrating the difference between the sterile and fertile pinnae. The
resemblance of some fertile pinnae of Coniopteris hymenophylloides to
those of Thyrsopteris elegans has led to a frequent use, without any solid
justification, of the generic name of the Juan Fernandez fern for Jurassic
and Wealden plants. It is not impossible that some of the fossils described
by Heer from Jurassic rocks of Siberia[905] as species of Thyrsopteris are
Cyatheaceous ferns, but it is impossible to say with certainty that they are
generically identical with the recent species. In his monograph of the
Potomac flora of Virginia[906] and Maryland, Fontaine has described as
species of Thyrsopteris several specimens of fronds which afford no
evidence as to the nature of the sori or sporangia. Some of the fronds
referred by this author to Thyrsopteris rarinervis[907], which I examined in
the Washington Museum, are in all probability examples of Onychiopsis, a
genus included in the Polypodiaceae. The fragments described by Lester
Ward[908] as species of Thyrsopteris from the Lower Cretaceous of the Black
Hills of North America afford no satisfactory evidence of relationship to the
recent type. Similarly Velenovský has described a Lower Cretaceous
Onychiopsis from Bohemia[909] as a species of Thyrsopteris, although the
fertile segments bear little or no resemblance to those of the Cyatheaceous
genus. Some fertile portions of fronds described by Heer[910] as Asplenium
Johnstrupi and afterwards as Dicksonia Johnstrupi[911] from the Cretaceous
beds (Kome series) of Greenland are very similar to Coniopteris
hymenophylloides.
Page 409
Fig. 272. Coniopteris hymenophylloides. Specimen from the Inferior Oolite, Scarborough; in
the York Museum. [M.S.]
Coniopteris quinqueloba (Phillips). Fig. 273.
This species, originally described by Phillips[912] as Sphenopteris
quinqueloba, is very similar in habit to C. hymenophylloides, differing
chiefly in the smaller size of the leaf and in the narrower ultimate segments.
The specimen shown in fig. 273, B, illustrates the form of the sorus and
sporangia.
the York Museum. [M.S.]
Coniopteris quinqueloba (Phillips). Fig. 273.
This species, originally described by Phillips[912] as Sphenopteris
quinqueloba, is very similar in habit to C. hymenophylloides, differing
chiefly in the smaller size of the leaf and in the narrower ultimate segments.
The specimen shown in fig. 273, B, illustrates the form of the sorus and
sporangia.
Page 410
Fig. 273. Coniopteris quinqueloba (Phillips). A, × 2; B, considerably enlarged. From
drawings supplied by Dr Nathorst.
Coniopteris arguta (Lind. and Hutt.[913]). Figs. 274, 275, A.
The sterile pinnae of this species bear pinnules of a type met with in
various species of ferns from different horizons; the smaller ones are entire
and slightly falcate, while on the lower part of a frond the ultimate
segments are longer and have a crenulate margin. The fertile pinnae bear
pinnules reduced to a midrib with a narrow border, and terminating in a
cup-like indusium (fig. 275, A). In habit the sterile leaf (fig. 274) of this
species is similar to the Jurassic Schizaeaceous fern Klukia exilis.
Protopteris.
Presl[914] instituted this genus for a Lower Cretaceous tree-fern from
Bohemia originally figured as Lepidodendron punctatum[915] and assigned to
a Palaeozoic horizon; it was afterwards named by Corda[916] Protopteris
Sternbergii and referred by Brongniart[917] to Sigillaria. The genus
Protopteris stands for fossil fern-stems with the habit and, in the main, the
structural features of recent tree-ferns. Persistent leaf-bases and sinuous
adventitious roots cover the surface of the stems: the vascular system is of
the dictyostelic type characteristic of Cyathea (fig. 240, p. 313) and
Alsophila. It is by the pattern formed by the vascular tissue on the exposed
surface of the leaf-bases that Protopteris is most readily recognised: the
leaf-trace has a horse-shoe form with the ends curled inwards and the sides
more or less indented (fig. 277). The generic name Caulopteris is used by
some authors in preference to Presl’s genus; but Protopteris is more
conveniently restricted to Mesozoic Cyatheaceous stems and Caulopteris to
drawings supplied by Dr Nathorst.
Coniopteris arguta (Lind. and Hutt.[913]). Figs. 274, 275, A.
The sterile pinnae of this species bear pinnules of a type met with in
various species of ferns from different horizons; the smaller ones are entire
and slightly falcate, while on the lower part of a frond the ultimate
segments are longer and have a crenulate margin. The fertile pinnae bear
pinnules reduced to a midrib with a narrow border, and terminating in a
cup-like indusium (fig. 275, A). In habit the sterile leaf (fig. 274) of this
species is similar to the Jurassic Schizaeaceous fern Klukia exilis.
Protopteris.
Presl[914] instituted this genus for a Lower Cretaceous tree-fern from
Bohemia originally figured as Lepidodendron punctatum[915] and assigned to
a Palaeozoic horizon; it was afterwards named by Corda[916] Protopteris
Sternbergii and referred by Brongniart[917] to Sigillaria. The genus
Protopteris stands for fossil fern-stems with the habit and, in the main, the
structural features of recent tree-ferns. Persistent leaf-bases and sinuous
adventitious roots cover the surface of the stems: the vascular system is of
the dictyostelic type characteristic of Cyathea (fig. 240, p. 313) and
Alsophila. It is by the pattern formed by the vascular tissue on the exposed
surface of the leaf-bases that Protopteris is most readily recognised: the
leaf-trace has a horse-shoe form with the ends curled inwards and the sides
more or less indented (fig. 277). The generic name Caulopteris is used by
some authors in preference to Presl’s genus; but Protopteris is more
conveniently restricted to Mesozoic Cyatheaceous stems and Caulopteris to
Page 411
Palaeozoic stems, with the internal structure of Psaronius (see Chap. xxiii.).
Stenzel applies Caulopteris to Mesozoic stems in which the leaf-trace
consists of several separate strands and not of a continuous band.
Fig. 274. Coniopteris arguta. (Nat. size. From a specimen in the Sedgwick Museum,
Cambridge.)
Stenzel applies Caulopteris to Mesozoic stems in which the leaf-trace
consists of several separate strands and not of a continuous band.
Fig. 274. Coniopteris arguta. (Nat. size. From a specimen in the Sedgwick Museum,
Cambridge.)
Page 412
Fig. 275.
A. Coniopteris arguta. (Fertile pinnae; nat. size.)
B. C. hymenophylloides.
A, from the Inferior Oolite of Yorkshire (British Museum); B, from Jurassic rocks in
Turkestan.
Lower Cretaceous casts of tree-fern stems in the Prague Museum have
been described under the names Alsophilina and Oncopteris; the figures of
the latter (fig. 276) given by Feistmantel[918] and by Velenovský[919] show the
petiole-bases arranged in vertical rows and characterised by leaf-traces
consisting of two separate strands in the form of two Vs lying on their sides.
Tree-fern stems described under various generic names are not
infrequently found in European Lower Cretaceous rocks: their comparative
abundance affords an example of striking changes in geographical
distribution since the latter part of the Mesozoic epoch. The Cyatheaceae no
longer exist in Europe and the arborescent species of the genus have
retreated to more southern regions.
A. Coniopteris arguta. (Fertile pinnae; nat. size.)
B. C. hymenophylloides.
A, from the Inferior Oolite of Yorkshire (British Museum); B, from Jurassic rocks in
Turkestan.
Lower Cretaceous casts of tree-fern stems in the Prague Museum have
been described under the names Alsophilina and Oncopteris; the figures of
the latter (fig. 276) given by Feistmantel[918] and by Velenovský[919] show the
petiole-bases arranged in vertical rows and characterised by leaf-traces
consisting of two separate strands in the form of two Vs lying on their sides.
Tree-fern stems described under various generic names are not
infrequently found in European Lower Cretaceous rocks: their comparative
abundance affords an example of striking changes in geographical
distribution since the latter part of the Mesozoic epoch. The Cyatheaceae no
longer exist in Europe and the arborescent species of the genus have
retreated to more southern regions.
Page 413
Fig. 276. Oncopteris Nettvalli. (After Velenovský; ¾ nat. size.)
Fig. 277. Protopteris punctata. (After Heer; very slightly reduced.)
Protopteris punctata (Sternb.). Fig. 277.
The earliest information in regard to the anatomy of this widely spread
Lower Cretaceous fern we owe to Corda, who showed that the species
Fig. 277. Protopteris punctata. (After Heer; very slightly reduced.)
Protopteris punctata (Sternb.). Fig. 277.
The earliest information in regard to the anatomy of this widely spread
Lower Cretaceous fern we owe to Corda, who showed that the species
Page 414
agrees in essentials with existing tree-ferns. The English example described
by Carruthers[920] from Upper Greensand beds in Dorsetshire (now in the
British Museum) shows only the external features. The sandstone cast (14
cm. in diameter), of which a portion is seen in fig. 277, was described by
Heer from Disco Island (Greenland) as a Carboniferous species[921], but
afterwards correctly assigned to the Cenomanian series[922] This species is
recorded also from the Lower Cretaceous of Bohemia by Frič and Bayer[923]
Among examples of petrified stems exhibiting a general agreement with
Protopteris punctata are those described by Stenzel[924] from Turonian rocks
in Germany. In one of these, Rhizodendron oppoliense Göpp., attention is
drawn to branches given off from the stem stele which have a solenostelic
structure in contrast to the dictyostele of the stem; also to the minute
structure of the tracheae which appear to have their ends perforated, a
feature shown by Gwynne-Vaughan[925] to be characteristic of the xylem
elements of many ferns.
by Carruthers[920] from Upper Greensand beds in Dorsetshire (now in the
British Museum) shows only the external features. The sandstone cast (14
cm. in diameter), of which a portion is seen in fig. 277, was described by
Heer from Disco Island (Greenland) as a Carboniferous species[921], but
afterwards correctly assigned to the Cenomanian series[922] This species is
recorded also from the Lower Cretaceous of Bohemia by Frič and Bayer[923]
Among examples of petrified stems exhibiting a general agreement with
Protopteris punctata are those described by Stenzel[924] from Turonian rocks
in Germany. In one of these, Rhizodendron oppoliense Göpp., attention is
drawn to branches given off from the stem stele which have a solenostelic
structure in contrast to the dictyostele of the stem; also to the minute
structure of the tracheae which appear to have their ends perforated, a
feature shown by Gwynne-Vaughan[925] to be characteristic of the xylem
elements of many ferns.
Page 415
Fig. 278.
A. Laccopteris polypodioides, Brongn. [From a specimen (39275) in the British Museum;
slightly reduced.]
B. L. Muensteri.
C. Dicksonia (petiole stele).
D. Onychiopsis Mantelli (fertile segments).
E. Hausmannia Sewardi Richt.
F. H. Kohlmanni Bicht.
G, H. Protopteris Witteana, Schenk. (x, xylem; R, roots.)
(B, after Schenk; E, F, after Richter.)
Protopteris Witteana Schenk[926] (fig. 278, G, H), a Wealden species
recorded from Germany and England, represents a closely allied or possibly
A. Laccopteris polypodioides, Brongn. [From a specimen (39275) in the British Museum;
slightly reduced.]
B. L. Muensteri.
C. Dicksonia (petiole stele).
D. Onychiopsis Mantelli (fertile segments).
E. Hausmannia Sewardi Richt.
F. H. Kohlmanni Bicht.
G, H. Protopteris Witteana, Schenk. (x, xylem; R, roots.)
(B, after Schenk; E, F, after Richter.)
Protopteris Witteana Schenk[926] (fig. 278, G, H), a Wealden species
recorded from Germany and England, represents a closely allied or possibly
Page 416
an identical type. The section of the stem (fig. H) shows the narrow
vascular bands, x, of a dictyostele similar to that of recent Cyatheaceous
tree-ferns and a form of meristele (fig. G, x) resembling that of P. punctata.
Adventitious roots are seen in section at R (figs. G and H).
Polypodiaceae.
Sections of petrified sporangia from the English Coal-Measures
(Pteridotheca sp.) occasionally exhibit a striking resemblance to those of
recent Polypodiaceae[927], but in the absence of material in which it is
possible to recognise the true orientation of the sporangia, the exact position
of the annulus is almost impossible to determine. We have as yet no
satisfactory evidence of the existence of true Polypodiaceae in the
Palaeozoic era. It is noteworthy that apart from the absence of ferns which
can reasonably be included in this family, the anatomical features of the
Botryopterideae (Coenopterideae) and of the Cycadofilices or
Pteridosperms do not foreshadow those of Polypodiaceous ferns. On the
other hand, as we have already noticed, anatomical characters of such
families as the Gleicheniaceae, Hymenophyllaceae, and Schizaeaceae are
met with in certain generalised Palaeozoic types. These facts are perhaps of
some importance as supplying collateral evidence in favour of the relatively
more recent origin of the dominant family of ferns in modern floras.
vascular bands, x, of a dictyostele similar to that of recent Cyatheaceous
tree-ferns and a form of meristele (fig. G, x) resembling that of P. punctata.
Adventitious roots are seen in section at R (figs. G and H).
Polypodiaceae.
Sections of petrified sporangia from the English Coal-Measures
(Pteridotheca sp.) occasionally exhibit a striking resemblance to those of
recent Polypodiaceae[927], but in the absence of material in which it is
possible to recognise the true orientation of the sporangia, the exact position
of the annulus is almost impossible to determine. We have as yet no
satisfactory evidence of the existence of true Polypodiaceae in the
Palaeozoic era. It is noteworthy that apart from the absence of ferns which
can reasonably be included in this family, the anatomical features of the
Botryopterideae (Coenopterideae) and of the Cycadofilices or
Pteridosperms do not foreshadow those of Polypodiaceous ferns. On the
other hand, as we have already noticed, anatomical characters of such
families as the Gleicheniaceae, Hymenophyllaceae, and Schizaeaceae are
met with in certain generalised Palaeozoic types. These facts are perhaps of
some importance as supplying collateral evidence in favour of the relatively
more recent origin of the dominant family of ferns in modern floras.
Page 417
Fig. 279.
A. Adiantides antiques (Ett.). (½ nat. size.)
B. A. Lindsayoides (Sew.). (B′ nat. size.)
(A, after Kidston.)
The use of the generic name Adiantites for fern-like fronds of Lower
Carboniferous age characterised by cuneate pinnules like those of species of
Adiantum, suggests an affinity which is in all probability non-existent. It
has been pointed out that this generic name was applied in the first instance
to the leaves of the Jurassic plant Ginkgo digitata[928] and should, therefore,
be discarded. Schimper[929] used the designation Adiantides, and
Ettingshausen[930], more rashly than wisely, preferred Adiantum. The
specimens described by Kidston[931] as Adiantides antiquus (Ett.) (fig. 279,
A) from the Carboniferous limestone of Flintshire are portions of tripinnate
fronds bearing cuneate segments with numerous forked veins radiating from
the contracted base of the lamina. It is not improbable, in view of Dr
White’s[932] discovery of seeds on a very similar plant from the Pottsville
beds of North America, that this characteristic Lower Carboniferous genus
is a Pteridosperm.
A. Adiantides antiques (Ett.). (½ nat. size.)
B. A. Lindsayoides (Sew.). (B′ nat. size.)
(A, after Kidston.)
The use of the generic name Adiantites for fern-like fronds of Lower
Carboniferous age characterised by cuneate pinnules like those of species of
Adiantum, suggests an affinity which is in all probability non-existent. It
has been pointed out that this generic name was applied in the first instance
to the leaves of the Jurassic plant Ginkgo digitata[928] and should, therefore,
be discarded. Schimper[929] used the designation Adiantides, and
Ettingshausen[930], more rashly than wisely, preferred Adiantum. The
specimens described by Kidston[931] as Adiantides antiquus (Ett.) (fig. 279,
A) from the Carboniferous limestone of Flintshire are portions of tripinnate
fronds bearing cuneate segments with numerous forked veins radiating from
the contracted base of the lamina. It is not improbable, in view of Dr
White’s[932] discovery of seeds on a very similar plant from the Pottsville
beds of North America, that this characteristic Lower Carboniferous genus
is a Pteridosperm.
Page 418
From Jurassic rocks in various parts of the world numerous fossils have
been described under the generic names Aspidium, Asplenium, Davallia,
Polypodium, and Pteris. In the great majority of cases such records leave
much to be desired from the point of view of students who appreciate the
dangers of relying on external similarity between vegetative organs, and on
resemblances founded on obscure impressions of sori. The generic term
Woodwardites[933], which suggests affinity with the recent genus
Woodwardia, has been used for Rhaetic plants belonging to the
Dipteridinae.
A plant described as Adiantides Lindsayoides from Jurassic rocks of
Victoria[934], characterised by marginal sori which appear to be protected by
the folded-over edge of the leaflets, and by the resemblance of the pinnules
to those of recent species of Lindsaya, may be a true Polypodiaceous fern;
but in this case, as in many similar instances, nothing is known of the
structure of the sporangia. Some sterile pinnae described by Yabe from
Jurassic rocks of Korea as Adiantites Sewardi[935] may perhaps be identical
with the Australian species.
In such a species as Polypodium oregonense Font., from Jurassic rocks of
Oregon, the generic name is chosen because the “fructification seems near
enough to that of Polypodium to justify the placing of the plant in that
genus[936].” But the fact that no sporangia have been found is a fatal
objection to this identification.
Onychiopsis.
This generic name was instituted by Yokoyama[937] for a Japanese
Wealden species, previously described by Geyler[938] as Thyrsopteris
elongata, on the ground that, in addition to a similarity in habit of the sterile
fronds, the fertile pinnae present a close agreement to those of the recent
genus Onychium.
Onychiopsis Mantelli[939] (Brongn.). Figs. 278, D; 280, A and B.
The Japanese species Onychiopsis elongata may perhaps be identical
with this common Wealden fern which, as Fontaine points out, should be
called O. psilotoides if the rule of priority is to be observed irrespective of
long usage.
been described under the generic names Aspidium, Asplenium, Davallia,
Polypodium, and Pteris. In the great majority of cases such records leave
much to be desired from the point of view of students who appreciate the
dangers of relying on external similarity between vegetative organs, and on
resemblances founded on obscure impressions of sori. The generic term
Woodwardites[933], which suggests affinity with the recent genus
Woodwardia, has been used for Rhaetic plants belonging to the
Dipteridinae.
A plant described as Adiantides Lindsayoides from Jurassic rocks of
Victoria[934], characterised by marginal sori which appear to be protected by
the folded-over edge of the leaflets, and by the resemblance of the pinnules
to those of recent species of Lindsaya, may be a true Polypodiaceous fern;
but in this case, as in many similar instances, nothing is known of the
structure of the sporangia. Some sterile pinnae described by Yabe from
Jurassic rocks of Korea as Adiantites Sewardi[935] may perhaps be identical
with the Australian species.
In such a species as Polypodium oregonense Font., from Jurassic rocks of
Oregon, the generic name is chosen because the “fructification seems near
enough to that of Polypodium to justify the placing of the plant in that
genus[936].” But the fact that no sporangia have been found is a fatal
objection to this identification.
Onychiopsis.
This generic name was instituted by Yokoyama[937] for a Japanese
Wealden species, previously described by Geyler[938] as Thyrsopteris
elongata, on the ground that, in addition to a similarity in habit of the sterile
fronds, the fertile pinnae present a close agreement to those of the recent
genus Onychium.
Onychiopsis Mantelli[939] (Brongn.). Figs. 278, D; 280, A and B.
The Japanese species Onychiopsis elongata may perhaps be identical
with this common Wealden fern which, as Fontaine points out, should be
called O. psilotoides if the rule of priority is to be observed irrespective of
long usage.
Page 419
Hymenopteris psilotoides, Stokes and Webb, Trans. Geol. Soc. [ii.],
1824.
Vol. i. p. 423, Pl. xlvi. fig. 7.
Sphenopteris Mantelli, Brongniart, Hist. vég. foss. p. 170, Pl. xlv.
1828.
figs. 3–7.
1890. Onychiopsis Mantelli, Nathorst, Denksch. Wien Akad. Vol. lvii. p. 5.
Onychiopsis Mantelli may be defined as follows:—
Frond bipinnate, ovate lanceolate, rachis winged; pinnae approximate, given off at an acute
angle; pinnules narrow, acuminate, with a single vein; the larger segments serrate and gradually
passing into pinnae with narrow ultimate segments. Fertile segments sessile or shortly stalked,
linear ovate, sometimes terminating in a short awn-like prolongation.
The fertile segments (fig. 278, D) bear so close a resemblance to those of
species of Onychium that it would seem justifiable to regard the plant as a
member of the Polypodiaceae. This fern is one of the most characteristic
members of the Wealden floras; it occurs in abundance in the English
Wealden, in Portugal, Germany, Belgium, Japan, Bohemia, South Africa,
and elsewhere. A piece of rhizome figured from the English Wealden[940] is
very similar to the creeping rhizomes of recent species of Polypodiaceae.
The English Wealden specimens shown in fig. 280, A and B, illustrate the
difference in form presented by leaves of this species; the smaller pinnae
reproduced in fig. A are more characteristic of the species than are those of
the slightly enlarged example represented in fig. 280, B.
1824.
Vol. i. p. 423, Pl. xlvi. fig. 7.
Sphenopteris Mantelli, Brongniart, Hist. vég. foss. p. 170, Pl. xlv.
1828.
figs. 3–7.
1890. Onychiopsis Mantelli, Nathorst, Denksch. Wien Akad. Vol. lvii. p. 5.
Onychiopsis Mantelli may be defined as follows:—
Frond bipinnate, ovate lanceolate, rachis winged; pinnae approximate, given off at an acute
angle; pinnules narrow, acuminate, with a single vein; the larger segments serrate and gradually
passing into pinnae with narrow ultimate segments. Fertile segments sessile or shortly stalked,
linear ovate, sometimes terminating in a short awn-like prolongation.
The fertile segments (fig. 278, D) bear so close a resemblance to those of
species of Onychium that it would seem justifiable to regard the plant as a
member of the Polypodiaceae. This fern is one of the most characteristic
members of the Wealden floras; it occurs in abundance in the English
Wealden, in Portugal, Germany, Belgium, Japan, Bohemia, South Africa,
and elsewhere. A piece of rhizome figured from the English Wealden[940] is
very similar to the creeping rhizomes of recent species of Polypodiaceae.
The English Wealden specimens shown in fig. 280, A and B, illustrate the
difference in form presented by leaves of this species; the smaller pinnae
reproduced in fig. A are more characteristic of the species than are those of
the slightly enlarged example represented in fig. 280, B.
Page 420
Fig. 280. Onychiopsis Mantelli. (From Wealden specimens in the British Museum; No.
13495 and No. V. 2615. A, natural size; B, very slightly enlarged.)
Among British Tertiary species referred to Polypodiaceae, it is interesting
to find what may well be an authentic record of a fern closely allied to the
recent tropical species Acrostichum (Chrysodium) aureum. This Eocene
species from Bournemouth is described as Chrysodium lanzaeanum[941]. The
frond is simply pinnate and apparently coriaceous in texture, with
lanceolate or oblong lanceolate pinnules (fig. 261, A, A′, p. 350), differing
from those of Acrostichum aureum in being sessile. A prominent midrib
gives off numerous anastomosing veins. No fertile pinnules have been
found.
Specimens described by Forbes from the Eocene beds of the Island of
Mull as Onoclea hebraidica[942] bear a strong likeness to the North
13495 and No. V. 2615. A, natural size; B, very slightly enlarged.)
Among British Tertiary species referred to Polypodiaceae, it is interesting
to find what may well be an authentic record of a fern closely allied to the
recent tropical species Acrostichum (Chrysodium) aureum. This Eocene
species from Bournemouth is described as Chrysodium lanzaeanum[941]. The
frond is simply pinnate and apparently coriaceous in texture, with
lanceolate or oblong lanceolate pinnules (fig. 261, A, A′, p. 350), differing
from those of Acrostichum aureum in being sessile. A prominent midrib
gives off numerous anastomosing veins. No fertile pinnules have been
found.
Specimens described by Forbes from the Eocene beds of the Island of
Mull as Onoclea hebraidica[942] bear a strong likeness to the North
Page 421
American and Japanese recent species Onoclea sensibilis. Fertile specimens
referred to the latter species are recorded by Knowlton[943] from Tertiary
beds of Montana.
A species described by Saporta[944] from the Eocene of Sézanne as
Adiantum apalophyllum is recorded by Gardner and Ettingshausen from
Bournemouth; an identification which is based on somewhat meagre
evidence.
The following remarks by Gardner and Ettingshausen are worthy of
repetition as calling attention to circumstances often overlooked in analyses
of fossil floras. They speak of ferns as relatively rare in British Eocene
rocks and add,—“the floras consist principally of deciduous dicotyledonous
leaves, which ... fell into the water and were tranquilly silted over. Ferns, on
the other hand, would require some violence to remove them from the place
of their growth, and their preservation would consequently be exceptional,
and they would be mutilated and fragmentary. This may account for their
rarity. Few as the British ferns are in the number of species, they
nevertheless form the largest and most important series of Eocene ferns,
even of Tertiary ferns, yet described from one group of beds[945].”
Dipteridinae.
Dictyophyllum.
This genus was founded by Lindley and Hutton for a pinnatifid leaf from
the Jurassic rocks of Yorkshire which they regarded as probably
dicotyledonous and named D. rugosum[946]. Several ferns of this genus have
since been found with well-preserved sori which demonstrate a close
similarity to the recent fern Dipteris. Dictyophyllum may be defined as
follows:—
Fronds large and palmate, characterised by the equal dichotomy of the
main rachis into two arms which curve outwards and then bend inwards
(fig. 281); from the surface of each arm are given off numerous spreading
pinnae with a lamina more or less deeply dissected into lobes varying in
breadth and in the form of the apex. Each lobe has a median vein, from
which branches are given off approximately at right angles and then
subdivide into a reticulum, in the meshes of which the veinlets end blindly
referred to the latter species are recorded by Knowlton[943] from Tertiary
beds of Montana.
A species described by Saporta[944] from the Eocene of Sézanne as
Adiantum apalophyllum is recorded by Gardner and Ettingshausen from
Bournemouth; an identification which is based on somewhat meagre
evidence.
The following remarks by Gardner and Ettingshausen are worthy of
repetition as calling attention to circumstances often overlooked in analyses
of fossil floras. They speak of ferns as relatively rare in British Eocene
rocks and add,—“the floras consist principally of deciduous dicotyledonous
leaves, which ... fell into the water and were tranquilly silted over. Ferns, on
the other hand, would require some violence to remove them from the place
of their growth, and their preservation would consequently be exceptional,
and they would be mutilated and fragmentary. This may account for their
rarity. Few as the British ferns are in the number of species, they
nevertheless form the largest and most important series of Eocene ferns,
even of Tertiary ferns, yet described from one group of beds[945].”
Dipteridinae.
Dictyophyllum.
This genus was founded by Lindley and Hutton for a pinnatifid leaf from
the Jurassic rocks of Yorkshire which they regarded as probably
dicotyledonous and named D. rugosum[946]. Several ferns of this genus have
since been found with well-preserved sori which demonstrate a close
similarity to the recent fern Dipteris. Dictyophyllum may be defined as
follows:—
Fronds large and palmate, characterised by the equal dichotomy of the
main rachis into two arms which curve outwards and then bend inwards
(fig. 281); from the surface of each arm are given off numerous spreading
pinnae with a lamina more or less deeply dissected into lobes varying in
breadth and in the form of the apex. Each lobe has a median vein, from
which branches are given off approximately at right angles and then
subdivide into a reticulum, in the meshes of which the veinlets end blindly
Page 422
(fig. 282, A and E). Sori composed of annulate sporangia are crowded on
the lower surface of the lamina. In habit and in sporangial characters the
genus closely resembles Dipteris, and in the branching of the frond suggests
comparison with Matonia. The rhizome (Rhizomopteris) is creeping and
dichotomously branched, bearing leaf-scars with a horse-shoe form of
vascular strand.
the lower surface of the lamina. In habit and in sporangial characters the
genus closely resembles Dipteris, and in the branching of the frond suggests
comparison with Matonia. The rhizome (Rhizomopteris) is creeping and
dichotomously branched, bearing leaf-scars with a horse-shoe form of
vascular strand.
Page 423
Fig. 281. Dictyophyllum exile. (After Nathorst; much reduced.)
Dictyophyllum is represented by several types to which various specific
names have been assigned, the distinguishing features being the form of the
pinna lobes, the degree of concrescence between the basal portions of the
pinnae, and similar features which in some cases can only be safely used as
criteria when large specimens are available for comparison.
Dictyophyllum exile (Brauns). Figs. 281, 282, D, E.
1862. Camptopteris exilis, Brauns, Palaeontograph. ix. p. 54.
Dictyophyllum acutilobum, Schenk, Foss. Flor. Grenz. p. 77, Pls.
1867.
xix. xx.
1878. D. exile, Nathorst, Flora vid Bjuf, i. p. 39, Pl. v. fig. 7.
— D. acutilobum, ibid. Pl. xi. fig. 1.
The restoration, after Nathorst[947], shown in fig. 281 illustrates the habit
of this striking fern, examples of which or of closely allied species are
recorded from Rhaetic rocks of Germany, Scania, Persia, Bornholm,
Tonkin, China, and elsewhere[948]. The petiole, reaching a length of 60 cm.,
forks at the apex into two equal arms leaving between them an oval space
and occasionally crossing one another. The axes of these branches are
Dictyophyllum is represented by several types to which various specific
names have been assigned, the distinguishing features being the form of the
pinna lobes, the degree of concrescence between the basal portions of the
pinnae, and similar features which in some cases can only be safely used as
criteria when large specimens are available for comparison.
Dictyophyllum exile (Brauns). Figs. 281, 282, D, E.
1862. Camptopteris exilis, Brauns, Palaeontograph. ix. p. 54.
Dictyophyllum acutilobum, Schenk, Foss. Flor. Grenz. p. 77, Pls.
1867.
xix. xx.
1878. D. exile, Nathorst, Flora vid Bjuf, i. p. 39, Pl. v. fig. 7.
— D. acutilobum, ibid. Pl. xi. fig. 1.
The restoration, after Nathorst[947], shown in fig. 281 illustrates the habit
of this striking fern, examples of which or of closely allied species are
recorded from Rhaetic rocks of Germany, Scania, Persia, Bornholm,
Tonkin, China, and elsewhere[948]. The petiole, reaching a length of 60 cm.,
forks at the apex into two equal arms leaving between them an oval space
and occasionally crossing one another. The axes of these branches are
Page 424
twisted so that the pinnae, which may be as many as 24 on each arm, and
arise from the inner side, by torsion of the axes assume an external position.
An interesting analogy as regards the twisted rachis of Dictyophyllum exile
and Camptopteris is afforded by the leaves of the Cycads, Macrozamia
Fawcettiae and M. corallipes, which are also characterised by the torsion of
the rachis. The habit, justly compared by Nathorst with that of Matonia
pectinata, affords another illustration of the common occurrence in older
ferns of a dichotomous system of branching. The pinnae, characterised by
circinate vernation, reach a length of 60 cm. and are divided into linear
lobes inclined obliquely or at right angles to the pinna axis. The whole of
the under surface of the lamina may be covered with sporangia, 4–7
sporangia in each sorus; the annulus is incomplete and approximately
vertical (fig. 282, D). The rhizome is probably represented by the
dichotomously branched axis described by Nathorst from Scania as
Rhizomopteris major; the leaf-scars show a horse-shoe leaf-trace.
arise from the inner side, by torsion of the axes assume an external position.
An interesting analogy as regards the twisted rachis of Dictyophyllum exile
and Camptopteris is afforded by the leaves of the Cycads, Macrozamia
Fawcettiae and M. corallipes, which are also characterised by the torsion of
the rachis. The habit, justly compared by Nathorst with that of Matonia
pectinata, affords another illustration of the common occurrence in older
ferns of a dichotomous system of branching. The pinnae, characterised by
circinate vernation, reach a length of 60 cm. and are divided into linear
lobes inclined obliquely or at right angles to the pinna axis. The whole of
the under surface of the lamina may be covered with sporangia, 4–7
sporangia in each sorus; the annulus is incomplete and approximately
vertical (fig. 282, D). The rhizome is probably represented by the
dichotomously branched axis described by Nathorst from Scania as
Rhizomopteris major; the leaf-scars show a horse-shoe leaf-trace.
Page 425
Fig. 282.
A. Dictyophyllum Nilssoni.
B. Rhizomopteris Schenki.
C. Camptopteris spiralis.
D, E. Dictyophyllum exile.
(After Nathorst; A, B, C, E, ⅔ nat. size.)
Dictyophyllum Nathorsti Zeiller[949].
This type, represented by a splendid series of specimens from the Rhaetic
beds of Tonkin, agrees very closely with D. exile. It differs, however, in the
basal parts of the pinnae which are concrescent for a length of 5 to 8 cm.
instead of free as in D. exile; and, to a slight degree, in the form of the
ultimate segments. In habit and in soral characters the two species are
practically identical. Each sorus contains 5 to 8 sporangia, which are rather
larger than those of Dipteris.
Dictyophyllum rugosum, Lind. and Hutt. Fig. 283.
A. Dictyophyllum Nilssoni.
B. Rhizomopteris Schenki.
C. Camptopteris spiralis.
D, E. Dictyophyllum exile.
(After Nathorst; A, B, C, E, ⅔ nat. size.)
Dictyophyllum Nathorsti Zeiller[949].
This type, represented by a splendid series of specimens from the Rhaetic
beds of Tonkin, agrees very closely with D. exile. It differs, however, in the
basal parts of the pinnae which are concrescent for a length of 5 to 8 cm.
instead of free as in D. exile; and, to a slight degree, in the form of the
ultimate segments. In habit and in soral characters the two species are
practically identical. Each sorus contains 5 to 8 sporangia, which are rather
larger than those of Dipteris.
Dictyophyllum rugosum, Lind. and Hutt. Fig. 283.
Page 426
1828. Phlebopteris Phillipsii, Brongniart, Hist. vég. foss. p. 377, Pl.
cxxxii. fig. 3; Pl. cxxxiii. fig. 1.
1829. Phyllites nervulosis, Phillips, Geol. Yorks. p. 148, Pl. viii. fig. 9.
1834. Dictyophyllum rugosum, Lindley and Hutton, Foss. Flor. ii. Pl. civ.
1836. Polypodites heracleifolius, Goeppert, Foss. Farn. p. 344.
1849. Camptopteris Phillipsii, Brongniart, Tableau, p. 105.
1880. Clathropteris whitbyensis, Nathorst, Berättelse, p. 83.
This species, which is characteristic of Jurassic rocks, is less completely
known than the two types described above, but in the form and venation of
the pinnae there is little difference between the Rhaetic and Jurassic plants.
The leaves of the Jurassic species appear to have been smaller and more
like those of Dipteris conjugata (fig. 231); there are no indications of the
existence of the two curved arms at the summit of the petiole which form so
striking a feature in D. exile and D. Nathorsti. No sporangia have been
found on English specimens, but it is safe to assume their agreement with
those of other species. A more complete list of records of D. rugosum is
given in the first volume of the British Museum Catalogue of Jurassic
plants[950].
cxxxii. fig. 3; Pl. cxxxiii. fig. 1.
1829. Phyllites nervulosis, Phillips, Geol. Yorks. p. 148, Pl. viii. fig. 9.
1834. Dictyophyllum rugosum, Lindley and Hutton, Foss. Flor. ii. Pl. civ.
1836. Polypodites heracleifolius, Goeppert, Foss. Farn. p. 344.
1849. Camptopteris Phillipsii, Brongniart, Tableau, p. 105.
1880. Clathropteris whitbyensis, Nathorst, Berättelse, p. 83.
This species, which is characteristic of Jurassic rocks, is less completely
known than the two types described above, but in the form and venation of
the pinnae there is little difference between the Rhaetic and Jurassic plants.
The leaves of the Jurassic species appear to have been smaller and more
like those of Dipteris conjugata (fig. 231); there are no indications of the
existence of the two curved arms at the summit of the petiole which form so
striking a feature in D. exile and D. Nathorsti. No sporangia have been
found on English specimens, but it is safe to assume their agreement with
those of other species. A more complete list of records of D. rugosum is
given in the first volume of the British Museum Catalogue of Jurassic
plants[950].
Page 427
Fig. 283. Dictyophyllum rugosum (Lind. and Hutt.). (Brit. Mus. Nat. size.)
Nathorst[951] has recently drawn attention to certain differences between
Dictyophyllum and Dipteris. The pinnate division of the pinnae is not
represented in the fronds of the recent species, but this method of lobing,
which is a marked characteristic of Dictyophyllum, is less prominent in
Clathropteris; and in Camptopteris lunzensis Stur[952], an Austrian Upper
Triassic species, the pinnae are entire. In Dictyophyllum the sori cover the
whole lower surface of the leaf; in Dipteris they are more widely separated
and the sporangia have a diameter of 0·02 mm., but in Dictyophyllum the
diameter is 0·4–0·6 mm. Moreover in Dictyophyllum the sori contain 5 to 8
Nathorst[951] has recently drawn attention to certain differences between
Dictyophyllum and Dipteris. The pinnate division of the pinnae is not
represented in the fronds of the recent species, but this method of lobing,
which is a marked characteristic of Dictyophyllum, is less prominent in
Clathropteris; and in Camptopteris lunzensis Stur[952], an Austrian Upper
Triassic species, the pinnae are entire. In Dictyophyllum the sori cover the
whole lower surface of the leaf; in Dipteris they are more widely separated
and the sporangia have a diameter of 0·02 mm., but in Dictyophyllum the
diameter is 0·4–0·6 mm. Moreover in Dictyophyllum the sori contain 5 to 8
Page 428
sporangia, whereas in Dipteris they are much more numerous. Despite these
differences it is clear, as Nathorst says, that Dictyophyllum, Clathropteris,
and Camptopteris are existing types very closely allied to Dipteris. It is a
matter of secondary importance whether we include all in the Dipteridinae
or follow Nathorst’s suggestion and refer the fossil genera to the separate
family Camptopteridinae.
Thaumatopteris.
This genus, founded by Goeppert[953] for a Rhaetic plant from Bayreuth,
is by some authors[954] regarded as identical with Dictyophyllum, but it has
recently been resuscitated by Nathorst[955] for specimens which he names T.
Schenki, formerly included by Schenk in his species T. Brauniana[956]. It
bears a close resemblance, in the long linear pinnules with an entire or
crenulate margin, to Dictyophyllum Fuchsi described by Zeiller[957] from
Tonkin, and it would seem hardly necessary to adopt a distinctive generic
designation. The sporangia have a vertical or slightly oblique annulus and
the rhizome is similar to that of Dictyophyllum exile. The habit of the genus
is shown in fig. 284, which represents one of the German Rhaetic species.
differences it is clear, as Nathorst says, that Dictyophyllum, Clathropteris,
and Camptopteris are existing types very closely allied to Dipteris. It is a
matter of secondary importance whether we include all in the Dipteridinae
or follow Nathorst’s suggestion and refer the fossil genera to the separate
family Camptopteridinae.
Thaumatopteris.
This genus, founded by Goeppert[953] for a Rhaetic plant from Bayreuth,
is by some authors[954] regarded as identical with Dictyophyllum, but it has
recently been resuscitated by Nathorst[955] for specimens which he names T.
Schenki, formerly included by Schenk in his species T. Brauniana[956]. It
bears a close resemblance, in the long linear pinnules with an entire or
crenulate margin, to Dictyophyllum Fuchsi described by Zeiller[957] from
Tonkin, and it would seem hardly necessary to adopt a distinctive generic
designation. The sporangia have a vertical or slightly oblique annulus and
the rhizome is similar to that of Dictyophyllum exile. The habit of the genus
is shown in fig. 284, which represents one of the German Rhaetic species.
Page 429
Fig. 284. Thaumatopteris Münsteri. (From a specimen in the Bergakademie, Berlin; ⅓ nat.
size.)
Clathropteris.
Clathropteris meniscoides, Brongn. Fig. 285.
Clathropteris, founded by Brongniart[958] for Rhaetic specimens from
Scania, agrees very closely with some species of Dictyophyllum, but in
view of the more rectangular form of the venation-meshes it is convenient
to retain both names. The type-species was originally named Filicites
meniscoides[959] and afterwards transferred to Clathropteris. An examination
of Brongniart’s specimens has convinced Nathorst of the specific identity of
C. meniscoides and C. platyphylla. The Tonkin leaves described by
Zeiller[960] under the latter name should, therefore, be included in C.
meniscoides, which may be thus defined:
size.)
Clathropteris.
Clathropteris meniscoides, Brongn. Fig. 285.
Clathropteris, founded by Brongniart[958] for Rhaetic specimens from
Scania, agrees very closely with some species of Dictyophyllum, but in
view of the more rectangular form of the venation-meshes it is convenient
to retain both names. The type-species was originally named Filicites
meniscoides[959] and afterwards transferred to Clathropteris. An examination
of Brongniart’s specimens has convinced Nathorst of the specific identity of
C. meniscoides and C. platyphylla. The Tonkin leaves described by
Zeiller[960] under the latter name should, therefore, be included in C.
meniscoides, which may be thus defined:
Page 430
The petiolate frond is characterised by an equal dichotomy of the rachis, as in Dictyophyllum;
each branch bore 5–15 pinnae, disposed en éventail, reaching a length of 20–30 cm. and fused
basally as in D. Nathorsti Zeill. Pinnae linear lanceolate, slightly contracted at the lower end and
gradually tapered distally. The lamina, 3–14 cm. broad, is characterised by obtusely pointed
marginal lobes. From the midrib of each pinna lateral veins are given off at a wide angle, and
adjacent veins are connected by a series of branches which divide the lamina into a regular
reticulum of rectangular and polygonal meshes (fig. 285). The sori are abundant and contain 5–
12 sporangia like those of Dictyophyllum.
Fig. 285. Clathropteris meniscoides. From Rhaetic rocks near Erlangen. [M.S.]
each branch bore 5–15 pinnae, disposed en éventail, reaching a length of 20–30 cm. and fused
basally as in D. Nathorsti Zeill. Pinnae linear lanceolate, slightly contracted at the lower end and
gradually tapered distally. The lamina, 3–14 cm. broad, is characterised by obtusely pointed
marginal lobes. From the midrib of each pinna lateral veins are given off at a wide angle, and
adjacent veins are connected by a series of branches which divide the lamina into a regular
reticulum of rectangular and polygonal meshes (fig. 285). The sori are abundant and contain 5–
12 sporangia like those of Dictyophyllum.
Fig. 285. Clathropteris meniscoides. From Rhaetic rocks near Erlangen. [M.S.]
Page 431
Fig. 286. Clathropteris egyptiaca. (Nat. size.) a, b, pieces of main ribs in grooves.
What is probably the rhizome of this species has been described by
Nathorst (Rhizomopteris cruciata); it is similar to that of Dictyophyllum, but
the leaf-scars are more widely separated. This species occurs in Upper
Triassic, Rhaetic or Lower Jurassic rocks of Scania, France, Germany,
Switzerland, Bornholm, North America, China, Tonkin, and Persia and is
represented by fragments in the Rhaetic beds of Bristol[961].
Clathropteris egyptiaca Sew.[962] Fig. 286.
The specimen on which this species was founded was discovered in the
Nubian Sandstone east of Edfu; the age of the beds is uncertain, but the
presence of Clathropteris suggests a Lower Jurassic or Rhaetic horizon[963].
Seven strong ribs radiate through the lamina from the summit of the petiole;
What is probably the rhizome of this species has been described by
Nathorst (Rhizomopteris cruciata); it is similar to that of Dictyophyllum, but
the leaf-scars are more widely separated. This species occurs in Upper
Triassic, Rhaetic or Lower Jurassic rocks of Scania, France, Germany,
Switzerland, Bornholm, North America, China, Tonkin, and Persia and is
represented by fragments in the Rhaetic beds of Bristol[961].
Clathropteris egyptiaca Sew.[962] Fig. 286.
The specimen on which this species was founded was discovered in the
Nubian Sandstone east of Edfu; the age of the beds is uncertain, but the
presence of Clathropteris suggests a Lower Jurassic or Rhaetic horizon[963].
Seven strong ribs radiate through the lamina from the summit of the petiole;
Page 432
at a and b small pieces of the projecting ribs are shown in the grooves.
From the main veins slender branches are given off at right angles and, as
seen in the enlarged drawing, these again subdivide into a delicate reticulum
with free-ending veinlets.
Fig. 287. Camptopteris spiralis. (After Nathorst. Much reduced.)
Camptopteris.
Camptopteris spiralis, Nath. Figs. 282, C; 287.
Nathorst proposed this generic name for Rhaetic fronds[964] resembling
those of Clathropteris and Dictyophyllum, but differing in the form of the
pinnae and in habit. The habit of the type-species, C. spiralis, is shown in
fig. 287. An examination of the specimens in the Stockholm Museum
convinced me of the correctness of Nathorst’s restoration[965]. Each of the
forked arms of the rachis bore as many as 150–160 long and narrow pinnae
characterised by an anastomosing venation (fig. 282, C) and by a spiral
From the main veins slender branches are given off at right angles and, as
seen in the enlarged drawing, these again subdivide into a delicate reticulum
with free-ending veinlets.
Fig. 287. Camptopteris spiralis. (After Nathorst. Much reduced.)
Camptopteris.
Camptopteris spiralis, Nath. Figs. 282, C; 287.
Nathorst proposed this generic name for Rhaetic fronds[964] resembling
those of Clathropteris and Dictyophyllum, but differing in the form of the
pinnae and in habit. The habit of the type-species, C. spiralis, is shown in
fig. 287. An examination of the specimens in the Stockholm Museum
convinced me of the correctness of Nathorst’s restoration[965]. Each of the
forked arms of the rachis bore as many as 150–160 long and narrow pinnae
characterised by an anastomosing venation (fig. 282, C) and by a spiral
Page 433
disposition due to the torsion of the axes. The sporangia agree in essentials
with those of Dictyophyllum.
Hausmannia.
A critical and exhaustive account of this genus has been given by Prof.
Von Richter[966] based on an examination of specimens found in the Lower
Cretaceous rocks of Quedlinburg in Germany. The name was proposed by
Dunker[967] for leaves from the Wealden of Germany characterised by a
deeply dissected dichotomously branched lamina. Andrae subsequently
instituted the genus Protorhipis[968] for suborbicular leaves with
dichotomously branched ribs from the Lias of Steierdorf. A similar but
smaller type of leaf was afterwards described by Zigno[969] from Jurassic
beds of Italy as P. asarifolius, and Nathorst[970] figured a closely allied form
from Rhaetic rocks of Sweden. While some authors regarded Hausmannia
and Protorhipis as ferns, others compared them with the leaves of Baiera
(Ginkgoales); Saporta suggested a dicotyledonous affinity for leaves of the
Protorhipis type. The true nature of the fossils was recognised by
Zeiller[971], who called attention to the very close resemblance in habit and
in soral characters to the recent genus Dipteris. A comparison of the
different species of Dipteris, including young leaves (fig. 231, p. 297), with
those of the fossil species reveals a very striking agreement[972]. There can
be no doubt, as Richter points out, that the names Hausmannia and
Protorhipis stand for one generic type.
Hausmannia may be defined as follows:
Rhizome creeping, slender, dichotomously branched; leaf-stalks slender (2–25 cm. long),
bearing a leathery lamina (1–12 cm. long and broad), wedge-shaped below, occasionally cordate
or reniform, entire or more or less deeply lobed into broad linear segments. The leaf is
characterised by dichotomously branched main ribs which arise from the summit of the rachis as
two divergent arms and radiate in a palmate manner, with repeated forking, through the lamina.
Lateral veins are given off at a wide angle, and, by subdivision, form a fairly regular network
similar to that in Dictyophyllum, Clathropteris, and Dipteris.
with those of Dictyophyllum.
Hausmannia.
A critical and exhaustive account of this genus has been given by Prof.
Von Richter[966] based on an examination of specimens found in the Lower
Cretaceous rocks of Quedlinburg in Germany. The name was proposed by
Dunker[967] for leaves from the Wealden of Germany characterised by a
deeply dissected dichotomously branched lamina. Andrae subsequently
instituted the genus Protorhipis[968] for suborbicular leaves with
dichotomously branched ribs from the Lias of Steierdorf. A similar but
smaller type of leaf was afterwards described by Zigno[969] from Jurassic
beds of Italy as P. asarifolius, and Nathorst[970] figured a closely allied form
from Rhaetic rocks of Sweden. While some authors regarded Hausmannia
and Protorhipis as ferns, others compared them with the leaves of Baiera
(Ginkgoales); Saporta suggested a dicotyledonous affinity for leaves of the
Protorhipis type. The true nature of the fossils was recognised by
Zeiller[971], who called attention to the very close resemblance in habit and
in soral characters to the recent genus Dipteris. A comparison of the
different species of Dipteris, including young leaves (fig. 231, p. 297), with
those of the fossil species reveals a very striking agreement[972]. There can
be no doubt, as Richter points out, that the names Hausmannia and
Protorhipis stand for one generic type.
Hausmannia may be defined as follows:
Rhizome creeping, slender, dichotomously branched; leaf-stalks slender (2–25 cm. long),
bearing a leathery lamina (1–12 cm. long and broad), wedge-shaped below, occasionally cordate
or reniform, entire or more or less deeply lobed into broad linear segments. The leaf is
characterised by dichotomously branched main ribs which arise from the summit of the rachis as
two divergent arms and radiate in a palmate manner, with repeated forking, through the lamina.
Lateral veins are given off at a wide angle, and, by subdivision, form a fairly regular network
similar to that in Dictyophyllum, Clathropteris, and Dipteris.
Page 434
Fig. 288. Hausmannia dichotoma. (Specimens from the late Dr Marcus Gunn’s Collection of
Upper Jurassic plants, Sutherlandshire; very slightly reduced.)
Hausmannia dichotoma, Dunker[973]. Fig. 288, A, B.
This Wealden species, represented in the North German flora and in beds
of approximately the same age at Quedlinburg, has been discovered by Dr
Marcus Gunn in Upper Jurassic rocks on the north-east coast of Scotland.
The lamina (12 cm. or more in length) is divided into five to seven linear
segments and bears a close superficial resemblance to leaves of Baiera and
to recent species of Schizaea (fig. 222, p. 287). Each segment contains one
Upper Jurassic plants, Sutherlandshire; very slightly reduced.)
Hausmannia dichotoma, Dunker[973]. Fig. 288, A, B.
This Wealden species, represented in the North German flora and in beds
of approximately the same age at Quedlinburg, has been discovered by Dr
Marcus Gunn in Upper Jurassic rocks on the north-east coast of Scotland.
The lamina (12 cm. or more in length) is divided into five to seven linear
segments and bears a close superficial resemblance to leaves of Baiera and
to recent species of Schizaea (fig. 222, p. 287). Each segment contains one
Page 435
or two main ribs (fig. 288, A). A similar form is described by Bartholin[974]
and by Moeller[975] as H. Forchammeri from Jurassic rocks of Bornholm.
Hausmannia Kohlmanni, Richt. Fig. 278, F.
In this species, instituted by Richter from material obtained from the
Lower Cretaceous beds of Strohberg[976], the comparatively slender rhizome
bears fronds with petioles reaching a length in extreme cases of 25 cm. but
usually of about 10 cm. The lamina (1–7 cm. long and 1–10 cm. broad) is
described as leathery, obcordate, and divided into two symmetrical halves
by a median sinus which, though occasionally extending more than half-
way through the lamina, is usually shallow. The venation consists of two
main branches which diverge from the summit of the petiole (fig. 278, F)
and subdivide into dichotomously branched ribs; finer veins (not shown in
the drawing) are given off from these at right angles and form more or less
rectangular meshes as in other members of the Dipteridinae and in such
recent ferns as Polypodium quercifolium (fig. 231, D, p. 297).
The imperfect lamina represented in fig. 289 may belong to Hausmannia
Richteri or may be a distinct species; it shows some of the finer veins
connecting the shorter forked ribs, which formed part of the reticulate
ramifying system in the mesophyll. This specimen was obtained from the
plant-beds of Culgower on the Sutherlandshire coast, which have been
placed by some geologists in the Kimmeridgian series.
The smaller type represented in fig. 278, E, is referred by Richter to a
distinct species, Hausmannia Sewardi[977], founded on a few specimens from
the Lower Cretaceous strata of Strohberg. This species is characterised by a
stouter rhizome bearing smaller leaves consisting of a short petiole (3–4
cm. long) and an obovate lamina (1–2 cm. long and broad). There are
usually two opposite leaflets on each leaf-stalk, and these may be
equivalent to the two halves of a single deeply dissected lamina.
and by Moeller[975] as H. Forchammeri from Jurassic rocks of Bornholm.
Hausmannia Kohlmanni, Richt. Fig. 278, F.
In this species, instituted by Richter from material obtained from the
Lower Cretaceous beds of Strohberg[976], the comparatively slender rhizome
bears fronds with petioles reaching a length in extreme cases of 25 cm. but
usually of about 10 cm. The lamina (1–7 cm. long and 1–10 cm. broad) is
described as leathery, obcordate, and divided into two symmetrical halves
by a median sinus which, though occasionally extending more than half-
way through the lamina, is usually shallow. The venation consists of two
main branches which diverge from the summit of the petiole (fig. 278, F)
and subdivide into dichotomously branched ribs; finer veins (not shown in
the drawing) are given off from these at right angles and form more or less
rectangular meshes as in other members of the Dipteridinae and in such
recent ferns as Polypodium quercifolium (fig. 231, D, p. 297).
The imperfect lamina represented in fig. 289 may belong to Hausmannia
Richteri or may be a distinct species; it shows some of the finer veins
connecting the shorter forked ribs, which formed part of the reticulate
ramifying system in the mesophyll. This specimen was obtained from the
plant-beds of Culgower on the Sutherlandshire coast, which have been
placed by some geologists in the Kimmeridgian series.
The smaller type represented in fig. 278, E, is referred by Richter to a
distinct species, Hausmannia Sewardi[977], founded on a few specimens from
the Lower Cretaceous strata of Strohberg. This species is characterised by a
stouter rhizome bearing smaller leaves consisting of a short petiole (3–4
cm. long) and an obovate lamina (1–2 cm. long and broad). There are
usually two opposite leaflets on each leaf-stalk, and these may be
equivalent to the two halves of a single deeply dissected lamina.
Page 436
Fig. 289. Hausmannia sp. Upper Jurassic, near Helmsdale, Scotland. From a specimen in
the British Museum. (Nat. size.)
It is interesting to compare these different forms of Hausmannia with the
fronds of recent species of Dipteris represented in fig. 231. The more
deeply dissected type, such as H. dichotoma, closely resembles D.
Lobbiana or D. quinquefurcata, while the more or less entire fossil leaves
(fig. 278, E, F and fig. 289) are very like the somewhat unusual form of
Dipteris conjugata shown in fig. 231, B, p. 297.
Other species of the genus are recorded from Liassic rocks of
Steierdorf[978] (Hungary) and of Bornholm[979]. Nathorst[980] has described a
small Rhaetic species from Scania: a French Permian plant described by
Zeiller[981] and compared by him with H. dichotoma, may be a Palaeozoic
example of this Dipteris-like genus.
Some segments of leaves from the Eocene beds (Middle Bagshot) of
Bournemouth, and now in the British Museum, described by Gardner and
Ettingshausen[982] as Podoloma polypodioides, bear a close resemblance in
the venation to the lamina of Dipteris conjugata.
the British Museum. (Nat. size.)
It is interesting to compare these different forms of Hausmannia with the
fronds of recent species of Dipteris represented in fig. 231. The more
deeply dissected type, such as H. dichotoma, closely resembles D.
Lobbiana or D. quinquefurcata, while the more or less entire fossil leaves
(fig. 278, E, F and fig. 289) are very like the somewhat unusual form of
Dipteris conjugata shown in fig. 231, B, p. 297.
Other species of the genus are recorded from Liassic rocks of
Steierdorf[978] (Hungary) and of Bornholm[979]. Nathorst[980] has described a
small Rhaetic species from Scania: a French Permian plant described by
Zeiller[981] and compared by him with H. dichotoma, may be a Palaeozoic
example of this Dipteris-like genus.
Some segments of leaves from the Eocene beds (Middle Bagshot) of
Bournemouth, and now in the British Museum, described by Gardner and
Ettingshausen[982] as Podoloma polypodioides, bear a close resemblance in
the venation to the lamina of Dipteris conjugata.
Page 437
Page 438
CHAPTER XXII.
Marattiales (Fossil).
The discovery of Pteridosperms has necessarily led to a considerable
modification of the views formerly held that existing genera of
Marattiaceae represent survivors of a group which occupied a dominant
position in the forests of the Coal age. Mr Arber writes:—“The evidence,
formerly regarded as beyond suspicion, that the eusporangiate ferns formed
a dominant feature of the vegetation of the Palaeozoic period, has been
undermined, more especially by the remarkable discovery of the male
organs of Lyginodendron by Mr Kidston. At best we can only now regard
them as a subsidiary group in that epoch in the past history of the vegetable
kingdom[983].” Dr Scott expresses himself in terms slightly more favourable
to the view that the Marattiaceae represent the aristocracy among the
Filicales. He says:—“We now have to seek laboriously for evidence, which
formerly seemed to lie open to us on all hands. I believe, however, that such
careful investigation will result in the resuscitation of the Palaeozoic ferns
as a considerable, though not as a dominant group[984].” Zeiller’s faith[985] in
the prospect of Marattiaceous ferns retaining their position as prominent
members of Palaeozoic floras, though shaken, is not extinguished: he
recognises that they played a subordinate part.
Reference has already been made to the impossibility of determining
whether Palaeozoic fern-like fronds may be legitimately retained in the
Filicales, or whether they must be removed into the ever widening territory
of the Pteridosperms. The difficulty is that the evidence of reproductive
organs is very far from decisive. In the absence of the female reproductive
organs, the seeds, we cannot in most cases be certain whether the small
sporangium-like bodies on fertile pinnules are true fern sporangia or the
microsporangia of a heterosporous pteridosperm. What is usually called an
exannulate fern sporangium, such as we have in Angiopteris and in many
Palaeozoic plants, has no distinguishing features which can be used as a
decisive test. The microsporophylls of the Mesozoic Bennettitales produced
Marattiales (Fossil).
The discovery of Pteridosperms has necessarily led to a considerable
modification of the views formerly held that existing genera of
Marattiaceae represent survivors of a group which occupied a dominant
position in the forests of the Coal age. Mr Arber writes:—“The evidence,
formerly regarded as beyond suspicion, that the eusporangiate ferns formed
a dominant feature of the vegetation of the Palaeozoic period, has been
undermined, more especially by the remarkable discovery of the male
organs of Lyginodendron by Mr Kidston. At best we can only now regard
them as a subsidiary group in that epoch in the past history of the vegetable
kingdom[983].” Dr Scott expresses himself in terms slightly more favourable
to the view that the Marattiaceae represent the aristocracy among the
Filicales. He says:—“We now have to seek laboriously for evidence, which
formerly seemed to lie open to us on all hands. I believe, however, that such
careful investigation will result in the resuscitation of the Palaeozoic ferns
as a considerable, though not as a dominant group[984].” Zeiller’s faith[985] in
the prospect of Marattiaceous ferns retaining their position as prominent
members of Palaeozoic floras, though shaken, is not extinguished: he
recognises that they played a subordinate part.
Reference has already been made to the impossibility of determining
whether Palaeozoic fern-like fronds may be legitimately retained in the
Filicales, or whether they must be removed into the ever widening territory
of the Pteridosperms. The difficulty is that the evidence of reproductive
organs is very far from decisive. In the absence of the female reproductive
organs, the seeds, we cannot in most cases be certain whether the small
sporangium-like bodies on fertile pinnules are true fern sporangia or the
microsporangia of a heterosporous pteridosperm. What is usually called an
exannulate fern sporangium, such as we have in Angiopteris and in many
Palaeozoic plants, has no distinguishing features which can be used as a
decisive test. The microsporophylls of the Mesozoic Bennettitales produced
Page 439
their spores in sporangial compartments grouped in synangia like those of
recent Marattiaceae; and in the case of Crossotheca, a type of frond always
regarded as Marattiaceous until Kidston[986] proved it to be the
microsporophyll of Lyginodendron, we have a striking instance of the
futility of making dogmatic assertions as to the filicinean nature of what
look like true fern sporangia. In all probability Dr Kidston’s surmise that the
supposed fern sporangia known as Dactylotheca, Renaultia, Urnatopteris
are the microsporangia of Pteridosperms will be proved correct[987]. The
question is how many of the supposed Marattiaceous sporangia must be
assigned to Pteridosperms? There is, however, no reasonable doubt that true
Marattiaceae formed a part of the Upper Carboniferous flora. All that can be
attempted in the following pages is to describe briefly some of the
numerous types of sporangia recognised on Palaeozoic fern-like foliage,
leaving to the future the task of deciding how many of them can be
accepted as those of ferns. It is impossible to avoid overlapping and some
repetition in the sections dealing with true Ferns and with Pteridosperms.
The filicinean nature of the stem known as Psaronius (see page 415) has
not as yet been questioned.
The nomenclature of supposed Marattiaceous species from Carboniferous
and Permian rocks is in a state of some confusion owing to a lack of
satisfactory distinguishing features between certain types to which different
generic names have been assigned. As we have already seen in the case of
supposed leptosporangiate sporangia, the interpretation of structural
features in petrified or carbonised sporangia does not afford an example of
unanimity among palaeobotanical experts.
Ptychocarpus.
This generic name, proposed by the late Professor Weiss[988], is applied to
a type of fructification illustrated by the plant which Brongniart named
Pecopteris unita, a species common in the Upper Coal-Measures of
England[989]. It is adopted by Kidston for fertile specimens from Radstock
which he describes as Ptychocarpus oblongus[990], but the precise nature of
the fertile pinnules of this species cannot be determined.
Ptychocarpus unita (Brongn.[991]). Fig. 291, A, B. (= Goniopteris unita,
Grand’Eury.)
recent Marattiaceae; and in the case of Crossotheca, a type of frond always
regarded as Marattiaceous until Kidston[986] proved it to be the
microsporophyll of Lyginodendron, we have a striking instance of the
futility of making dogmatic assertions as to the filicinean nature of what
look like true fern sporangia. In all probability Dr Kidston’s surmise that the
supposed fern sporangia known as Dactylotheca, Renaultia, Urnatopteris
are the microsporangia of Pteridosperms will be proved correct[987]. The
question is how many of the supposed Marattiaceous sporangia must be
assigned to Pteridosperms? There is, however, no reasonable doubt that true
Marattiaceae formed a part of the Upper Carboniferous flora. All that can be
attempted in the following pages is to describe briefly some of the
numerous types of sporangia recognised on Palaeozoic fern-like foliage,
leaving to the future the task of deciding how many of them can be
accepted as those of ferns. It is impossible to avoid overlapping and some
repetition in the sections dealing with true Ferns and with Pteridosperms.
The filicinean nature of the stem known as Psaronius (see page 415) has
not as yet been questioned.
The nomenclature of supposed Marattiaceous species from Carboniferous
and Permian rocks is in a state of some confusion owing to a lack of
satisfactory distinguishing features between certain types to which different
generic names have been assigned. As we have already seen in the case of
supposed leptosporangiate sporangia, the interpretation of structural
features in petrified or carbonised sporangia does not afford an example of
unanimity among palaeobotanical experts.
Ptychocarpus.
This generic name, proposed by the late Professor Weiss[988], is applied to
a type of fructification illustrated by the plant which Brongniart named
Pecopteris unita, a species common in the Upper Coal-Measures of
England[989]. It is adopted by Kidston for fertile specimens from Radstock
which he describes as Ptychocarpus oblongus[990], but the precise nature of
the fertile pinnules of this species cannot be determined.
Ptychocarpus unita (Brongn.[991]). Fig. 291, A, B. (= Goniopteris unita,
Grand’Eury.)
Page 440
This species has tripinnate fronds with linear pinnae bearing contiguous
pinnules of the Pecopteris type (fig. 291, B), 4–5 mm. long, confluent at the
base or for the greater part of their length. On the under surface of the
fertile segments, which are identical with the sterile, occur circular synangia
(fig. 291, A) consisting of seven sporangia embedded in a common
parenchymatous tissue and radially disposed round a receptacle supplied
with vascular tissue. The synangium is described as shortly stalked like
those of Marattia Kaulfussii (fig. 245, B′, p. 320). In shape, in the complete
union of the sporangia, and presumably in the apical dehiscence,
Ptychocarpus agrees very closely with Kaulfussia (fig. 245); but we cannot
be certain that we have not a collection of microsporangia simulating a fern
synangium.
A synangium closely resembling Ptychocarpus has been described by Mr
Watson[992] from the Lower Coal-Measures of Lancashire as Cyathotrachus
altus, but there is no convincing evidence as to the nature of the plant on
which it was borne.
Danaeites.
This generic name, instituted by Goeppert[993], has been used by authors
without due regard to the nature of the evidence of affinity to Danaea. The
type named by Stur Danaeites sarepontanus[994] (fig. 291, E) bears small
pecopteroid pinnules with ovoid sporangia in groups of 8–16 in two
contiguous series on the lower face of the lamina. The sporangia dehisce by
an apical pore and are more or less embedded in the mesophyll of the
segments. No figures have been published showing any detailed sporangial
structure, and such evidence as we have is insufficient to warrant the
conclusion that the resemblance to Danaea is more than an analogy.
Parapecopteris.
Parapecopteris neuropteroides, Grand’Eury. Fig. 290, D.
The plant described by Grand’Eury[995] from the Coal-fields of Gard and
St Étienne, and made the type of a new genus, is characterised by pinnules
intermediate between those of Pecopteris and Neuropteris[996] and by the
pinnules of the Pecopteris type (fig. 291, B), 4–5 mm. long, confluent at the
base or for the greater part of their length. On the under surface of the
fertile segments, which are identical with the sterile, occur circular synangia
(fig. 291, A) consisting of seven sporangia embedded in a common
parenchymatous tissue and radially disposed round a receptacle supplied
with vascular tissue. The synangium is described as shortly stalked like
those of Marattia Kaulfussii (fig. 245, B′, p. 320). In shape, in the complete
union of the sporangia, and presumably in the apical dehiscence,
Ptychocarpus agrees very closely with Kaulfussia (fig. 245); but we cannot
be certain that we have not a collection of microsporangia simulating a fern
synangium.
A synangium closely resembling Ptychocarpus has been described by Mr
Watson[992] from the Lower Coal-Measures of Lancashire as Cyathotrachus
altus, but there is no convincing evidence as to the nature of the plant on
which it was borne.
Danaeites.
This generic name, instituted by Goeppert[993], has been used by authors
without due regard to the nature of the evidence of affinity to Danaea. The
type named by Stur Danaeites sarepontanus[994] (fig. 291, E) bears small
pecopteroid pinnules with ovoid sporangia in groups of 8–16 in two
contiguous series on the lower face of the lamina. The sporangia dehisce by
an apical pore and are more or less embedded in the mesophyll of the
segments. No figures have been published showing any detailed sporangial
structure, and such evidence as we have is insufficient to warrant the
conclusion that the resemblance to Danaea is more than an analogy.
Parapecopteris.
Parapecopteris neuropteroides, Grand’Eury. Fig. 290, D.
The plant described by Grand’Eury[995] from the Coal-fields of Gard and
St Étienne, and made the type of a new genus, is characterised by pinnules
intermediate between those of Pecopteris and Neuropteris[996] and by the
Page 441
presence of two rows of united sporangia along the lateral veins, as in
Danaea and Danaeites.
Asterotheca.
Certain species of Pecopteris fronds from Carboniferous strata are
characterised by circular sori or synangia consisting of a small number (3–
8) of exannulate sporangia attached to a central receptacle and free only at
their apices. Strasburger[997] suggested a Marattiaceous affinity for
Asterotheca and Stur[998] describes the species Asterotheca Sternbergii
Goepp. (fig. 291, C, D) as an example of a Marattiaceous fern. The latter
author retains Corda’s genus Hawlea[999] for the fertile fronds of the
common Coal-Measures species Pecopteris Miltoni, while on the other
hand Kidston[1000] includes this type in Asterotheca.
Pecopteris (Asterotheca) Miltoni (Artis).
1825.Filicites Miltoni, Artis, Antedil. Phyt. Pl. xiv.
1828.Pecopteris Miltoni, Brongniart, Prodrome, p. 58.
1828.Pecopteris abbreviata, Brongniart, Hist. vég. foss. p. 337, Pl.
cxv. figs. 1–4; Lindley and Hutton, Foss. Flor. Vol. iii. Pl. 184.
1845. Hawlea pulcherrima, Corda, Flor. Vorwelt, p. 90, Pl. lvii. figs. 7,
8.
1877– Hawlea Miltoni, Stur, Culm Flora, p. 293; Farne Carbon. Flora,
1888. p. 108, Pls. lix. lx.
1888. Pecopteris (Asterotheca) abbreviata, Zeiller, Flor. Valenc. p. 186,
Pl. xxiv. figs. 1–4.
Danaea and Danaeites.
Asterotheca.
Certain species of Pecopteris fronds from Carboniferous strata are
characterised by circular sori or synangia consisting of a small number (3–
8) of exannulate sporangia attached to a central receptacle and free only at
their apices. Strasburger[997] suggested a Marattiaceous affinity for
Asterotheca and Stur[998] describes the species Asterotheca Sternbergii
Goepp. (fig. 291, C, D) as an example of a Marattiaceous fern. The latter
author retains Corda’s genus Hawlea[999] for the fertile fronds of the
common Coal-Measures species Pecopteris Miltoni, while on the other
hand Kidston[1000] includes this type in Asterotheca.
Pecopteris (Asterotheca) Miltoni (Artis).
1825.Filicites Miltoni, Artis, Antedil. Phyt. Pl. xiv.
1828.Pecopteris Miltoni, Brongniart, Prodrome, p. 58.
1828.Pecopteris abbreviata, Brongniart, Hist. vég. foss. p. 337, Pl.
cxv. figs. 1–4; Lindley and Hutton, Foss. Flor. Vol. iii. Pl. 184.
1845. Hawlea pulcherrima, Corda, Flor. Vorwelt, p. 90, Pl. lvii. figs. 7,
8.
1877– Hawlea Miltoni, Stur, Culm Flora, p. 293; Farne Carbon. Flora,
1888. p. 108, Pls. lix. lx.
1888. Pecopteris (Asterotheca) abbreviata, Zeiller, Flor. Valenc. p. 186,
Pl. xxiv. figs. 1–4.
Page 442
Fig. 290.
A. Alethopteris lonchitica. × 2½. | For description
B. Lonchopteris rugosa. × 2. | see; Chap. xxvii.
C. Sphenopteris Hoeninghausi. × 4. |
D. Parapecopteris neuropteroides.
E. Pecopteris (Dactylotheca) plumosa [= P. (Dactylotheca) dentata Zeiller (88)]. × 4.
(A–C, E, after Zeiller; D, after Grand’Eury.)
The fronds of this species reached a length of more than 3 metres and a
breadth of 2 metres. They are characterised by the presence of aphlebiae[1001]
appressed to the rachis and by circular sori composed of a small number (3–
6) of sporangia. In habit and in the form of the pinnules this type is similar
to Dactylotheca plumosa.
A. Alethopteris lonchitica. × 2½. | For description
B. Lonchopteris rugosa. × 2. | see; Chap. xxvii.
C. Sphenopteris Hoeninghausi. × 4. |
D. Parapecopteris neuropteroides.
E. Pecopteris (Dactylotheca) plumosa [= P. (Dactylotheca) dentata Zeiller (88)]. × 4.
(A–C, E, after Zeiller; D, after Grand’Eury.)
The fronds of this species reached a length of more than 3 metres and a
breadth of 2 metres. They are characterised by the presence of aphlebiae[1001]
appressed to the rachis and by circular sori composed of a small number (3–
6) of sporangia. In habit and in the form of the pinnules this type is similar
to Dactylotheca plumosa.
Page 443
Fig. 291.
A, B. Ptychocarpus unita.
C, D. Asterotheca Sternbergii.
E. Danaeites sarepontanus.
F. Hawlea Miltoni.
G. Hawlea pulcherrima.
H–K. Scolecopteris elegans.
(A, B, after Renault; C–G, after Stur; H, I, after Strasburger; K, after Sterzel.)
Hawlea.
Stur[1002] retains this generic name for sori in which the sporangia are free
and united only by the proximal end to a central receptacle (fig. 291, F, G).
He describes the individual sporangia as possessing a rudimentary annulus,
a comparatively strong wall, and terminating in a pointed distal end. He
A, B. Ptychocarpus unita.
C, D. Asterotheca Sternbergii.
E. Danaeites sarepontanus.
F. Hawlea Miltoni.
G. Hawlea pulcherrima.
H–K. Scolecopteris elegans.
(A, B, after Renault; C–G, after Stur; H, I, after Strasburger; K, after Sterzel.)
Hawlea.
Stur[1002] retains this generic name for sori in which the sporangia are free
and united only by the proximal end to a central receptacle (fig. 291, F, G).
He describes the individual sporangia as possessing a rudimentary annulus,
a comparatively strong wall, and terminating in a pointed distal end. He
Page 444
emphasises the greater degree of cohesion between the sporangia of
Asterotheca as the distinguishing feature of that genus; but this is a
character difficult to recognise in some cases, and from the analogy of
recent ferns one is disposed to attach little importance to the greater or less
extent to which sporangia are united, at least in such cases as Asterotheca
and Hawlea when the cohesion is never complete.
Scolecopteris.
Zenker[1003] gave this name to detached fertile pinnules from the Lower
Permian of Saxony, which he described as Scolecopteris elegans. He
recognised the fern nature of the sori and suggested that the pinnules might
belong to the fronds of one of the “Staarsteinen” (Psaronius), a view which
subsequent investigations render far from improbable. The sori, which
occur in two rows on the lower surface of the small pecopteroid segments
with strongly revolute margins (fig. 291, H–K), contain 4–5 sporangia
attached to a stalked receptacle comparable with that of Marattia
Kaulfussii. These pedicellate synangia were fully described by
Strasburger[1004], who decided in favour of a Marattiaceous alliance. The
lower portions of the distally tapered sporangia are concrescent, the distal
ends being free (fig. 291, H). Stur includes in Scolecopteris the common
species Pecopteris arborescens (fig. 376), but Kidston[1005] states that the
British example of Scolecopteris is S. polymorpha, Brongn. from the Upper
Coal-Measures.
Scolecopteris elegans Zenk. furnishes an example of a plant, or plant
fragment, which has been assigned to the animal kingdom. Geinitz[1006]
described silicified pinnules as Palaeojulus dyadicus, the generic name
being chosen because of the resemblance to Millipedes such as the genus
Julus. The mistake is not surprising to anyone who has seen a block of
siliceous rock from Chemnitz crowded with the small pinnules with their
concave surfaces formed by the infolding of the edges. Sterzel[1007], who
pointed out the confusion between Myriapods and Filices, has published
figures which illustrate the deceptive resemblance of the pinnules, with
their curved lamina divided by lateral veins into segments, to the body of a
Millipede (fig. 291, K). He points out that Geinitz searched in vain for the
head and legs of Palaeojulus and expressed the hope that further
examination would lead to fresh discoveries: the examination of sections
Asterotheca as the distinguishing feature of that genus; but this is a
character difficult to recognise in some cases, and from the analogy of
recent ferns one is disposed to attach little importance to the greater or less
extent to which sporangia are united, at least in such cases as Asterotheca
and Hawlea when the cohesion is never complete.
Scolecopteris.
Zenker[1003] gave this name to detached fertile pinnules from the Lower
Permian of Saxony, which he described as Scolecopteris elegans. He
recognised the fern nature of the sori and suggested that the pinnules might
belong to the fronds of one of the “Staarsteinen” (Psaronius), a view which
subsequent investigations render far from improbable. The sori, which
occur in two rows on the lower surface of the small pecopteroid segments
with strongly revolute margins (fig. 291, H–K), contain 4–5 sporangia
attached to a stalked receptacle comparable with that of Marattia
Kaulfussii. These pedicellate synangia were fully described by
Strasburger[1004], who decided in favour of a Marattiaceous alliance. The
lower portions of the distally tapered sporangia are concrescent, the distal
ends being free (fig. 291, H). Stur includes in Scolecopteris the common
species Pecopteris arborescens (fig. 376), but Kidston[1005] states that the
British example of Scolecopteris is S. polymorpha, Brongn. from the Upper
Coal-Measures.
Scolecopteris elegans Zenk. furnishes an example of a plant, or plant
fragment, which has been assigned to the animal kingdom. Geinitz[1006]
described silicified pinnules as Palaeojulus dyadicus, the generic name
being chosen because of the resemblance to Millipedes such as the genus
Julus. The mistake is not surprising to anyone who has seen a block of
siliceous rock from Chemnitz crowded with the small pinnules with their
concave surfaces formed by the infolding of the edges. Sterzel[1007], who
pointed out the confusion between Myriapods and Filices, has published
figures which illustrate the deceptive resemblance of the pinnules, with
their curved lamina divided by lateral veins into segments, to the body of a
Millipede (fig. 291, K). He points out that Geinitz searched in vain for the
head and legs of Palaeojulus and expressed the hope that further
examination would lead to fresh discoveries: the examination of sections
Page 445
revealed the presence of sporangia and demonstrated the identity of
Palaeojulus and Scolecopteris.
Discopteris.
Stur[1008] instituted this genus for fertile fronds from the Upper
Carboniferous Schatzlarer beds, including two species Discopteris
karwinensis and D. Schumanni. He described the small Sphenopteroid
pinnules as characterised by disc-shaped sori made up of 70–100 sporangia
attached to a hemispherical receptacle: the absence of a true annulus led
him to refer the genus to the Marattiaceae. In his memoir on the coal-basin
of Heraclea (Asia Minor), Zeiller[1009] instituted the species Sphenopteris
(Discopteris) Rallii and figured sporangia resembling those described by
Stur in the possession of a rudimentary “apical annulus.” He compared the
sporangia with those of recent Osmundaceae and Marattiaceae. In the later
memoir on the Upper Carboniferous and Permian plants of Blanzy and
Creusot, Zeiller[1010] gives a very full and careful description of fertile
specimens of Sphenopteris (Discopteris) cristata, a fern originally
described by Brongniart as Pecopteris cristata[1011]. Many of the
Sphenopteroid pinnules of this quadripinnate fern frond show the form and
structure of the sori with remarkable clearness in the admirable photographs
reproduced in Plates i.–iii. of Zeiller’s Blanzy memoir. The lobed pinnules
of this species are of oval-triangular form, 5–15 mm. long and 2·5–6 mm.
broad[1012]. An examination of the type-specimens of Discopteris from
Vienna enabled Zeiller to correct Stur’s original description of the sori: he
found that the Austrian and French specimens, though specifically distinct,
undoubtedly belong to one genus. The sori in Discopteris cristata are
globular, as in the recent genera Cyathea and Alsophila, and frequently
cover the whole face of the lamina. The individual sporangia are 0·4–0·5
mm. long and 0·15–0·2 mm. in diameter; they are exannulate, but for the
annulus is substituted a group of thicker-walled and larger cells in the apical
and dorsal region. The description by Stur of a hemispherical receptacle
seemed to indicate an important difference between the Austrian and French
species; but Zeiller found that this feature does not actually exist and that it
was so described as the result of misinterpretation. Zeiller succeeded in
isolating spores, 40–50 μ in diameter, from some of the sporangia of D.
cristata and found that they exhibited the three-rayed pattern characteristic
of fern-spores and which is indicative of their formation in tetrads. The
Palaeojulus and Scolecopteris.
Discopteris.
Stur[1008] instituted this genus for fertile fronds from the Upper
Carboniferous Schatzlarer beds, including two species Discopteris
karwinensis and D. Schumanni. He described the small Sphenopteroid
pinnules as characterised by disc-shaped sori made up of 70–100 sporangia
attached to a hemispherical receptacle: the absence of a true annulus led
him to refer the genus to the Marattiaceae. In his memoir on the coal-basin
of Heraclea (Asia Minor), Zeiller[1009] instituted the species Sphenopteris
(Discopteris) Rallii and figured sporangia resembling those described by
Stur in the possession of a rudimentary “apical annulus.” He compared the
sporangia with those of recent Osmundaceae and Marattiaceae. In the later
memoir on the Upper Carboniferous and Permian plants of Blanzy and
Creusot, Zeiller[1010] gives a very full and careful description of fertile
specimens of Sphenopteris (Discopteris) cristata, a fern originally
described by Brongniart as Pecopteris cristata[1011]. Many of the
Sphenopteroid pinnules of this quadripinnate fern frond show the form and
structure of the sori with remarkable clearness in the admirable photographs
reproduced in Plates i.–iii. of Zeiller’s Blanzy memoir. The lobed pinnules
of this species are of oval-triangular form, 5–15 mm. long and 2·5–6 mm.
broad[1012]. An examination of the type-specimens of Discopteris from
Vienna enabled Zeiller to correct Stur’s original description of the sori: he
found that the Austrian and French specimens, though specifically distinct,
undoubtedly belong to one genus. The sori in Discopteris cristata are
globular, as in the recent genera Cyathea and Alsophila, and frequently
cover the whole face of the lamina. The individual sporangia are 0·4–0·5
mm. long and 0·15–0·2 mm. in diameter; they are exannulate, but for the
annulus is substituted a group of thicker-walled and larger cells in the apical
and dorsal region. The description by Stur of a hemispherical receptacle
seemed to indicate an important difference between the Austrian and French
species; but Zeiller found that this feature does not actually exist and that it
was so described as the result of misinterpretation. Zeiller succeeded in
isolating spores, 40–50 μ in diameter, from some of the sporangia of D.
cristata and found that they exhibited the three-rayed pattern characteristic
of fern-spores and which is indicative of their formation in tetrads. The
Page 446
conclusion arrived at is that the genus Discopteris, as represented by D.
karwinensis, D. cristata etc., may be regarded as a true fern and included in
the Marattiaceae. As Zeiller points out, the sori of Discopteris differ from
those of recent Marattiaceae in their pluriseriate construction and agree in
this respect with those of the Cyatheaceae. The comparison already
made[1013] between the sporangia of D. Rallii and those of recent
Osmundaceae holds good: the genus affords another example of a
generalised type, in this case probably a fern, combining features which are
now distributed among the Marattiaceae, Osmundaceae and Cyatheaceae.
• • • • •
In addition to genera founded on true synangia or groups of free or
partially united sporangia, the literature of Palaeozoic ferns contains several
generic names applied to sporangia which occur singly on Sphenopteroid or
Pecopteroid pinnules. The following may serve as examples; but it should
be stated that these will probably be transferred eventually to the
Pteridosperms. It is, however, immaterial whether they are dealt with here
or in the chapter devoted to the seed-bearing “ferns.”
Dactylotheca.
Zeiller[1014] created this genus for fertile fronds of Pecopteris dentata
Brongn. (= P. plumosa Artis[1015]), a common British species in the Upper
and Middle Coal-Measures. Stur[1016] included P. dentata in his list of
species of Senftenbergia, the genus to which reference was made under the
Schizaeaceae.
Pecopteris (Dactylotheca) plumosa (Artis). Figs. 290, E, 292, 293.
1825. Filicites plumosus, Artis, Antedil. Phyt. p. 17, Pl. xvii.
1828. Pecopteris plumosa, Brongniart, Hist. vég. foss. p. 348, Pls. cxxi.
cxxii.
— P. dentata, Brongniart, ibid. Pls. cxxiii. cxxiv.
— P. delicatulus, Brongniart, ibid. Pl. cxvi. fig. 6.
1832. Sphenopteris caudata, Lindley and Hutton, Foss. Flor. Vol. i. Pl.
xlviii.; Vol. ii. Pl. cxxxviii.
1834. Pecopteris serra, Lindley and Hutton, ibid. Vol. ii. Pl. cvii.
karwinensis, D. cristata etc., may be regarded as a true fern and included in
the Marattiaceae. As Zeiller points out, the sori of Discopteris differ from
those of recent Marattiaceae in their pluriseriate construction and agree in
this respect with those of the Cyatheaceae. The comparison already
made[1013] between the sporangia of D. Rallii and those of recent
Osmundaceae holds good: the genus affords another example of a
generalised type, in this case probably a fern, combining features which are
now distributed among the Marattiaceae, Osmundaceae and Cyatheaceae.
• • • • •
In addition to genera founded on true synangia or groups of free or
partially united sporangia, the literature of Palaeozoic ferns contains several
generic names applied to sporangia which occur singly on Sphenopteroid or
Pecopteroid pinnules. The following may serve as examples; but it should
be stated that these will probably be transferred eventually to the
Pteridosperms. It is, however, immaterial whether they are dealt with here
or in the chapter devoted to the seed-bearing “ferns.”
Dactylotheca.
Zeiller[1014] created this genus for fertile fronds of Pecopteris dentata
Brongn. (= P. plumosa Artis[1015]), a common British species in the Upper
and Middle Coal-Measures. Stur[1016] included P. dentata in his list of
species of Senftenbergia, the genus to which reference was made under the
Schizaeaceae.
Pecopteris (Dactylotheca) plumosa (Artis). Figs. 290, E, 292, 293.
1825. Filicites plumosus, Artis, Antedil. Phyt. p. 17, Pl. xvii.
1828. Pecopteris plumosa, Brongniart, Hist. vég. foss. p. 348, Pls. cxxi.
cxxii.
— P. dentata, Brongniart, ibid. Pls. cxxiii. cxxiv.
— P. delicatulus, Brongniart, ibid. Pl. cxvi. fig. 6.
1832. Sphenopteris caudata, Lindley and Hutton, Foss. Flor. Vol. i. Pl.
xlviii.; Vol. ii. Pl. cxxxviii.
1834. Pecopteris serra, Lindley and Hutton, ibid. Vol. ii. Pl. cvii.
Page 447
1834. Schizopteris adnascens, Lindley and Hutton, ibid. Vol. i. Pls. c. ci.
1836. Aspidites caudatus, Goeppert, Syst. fil. foss. p. 363.
1838. Steffensia silesiaca, Presl, in Sternberg, Flor. Vorwelt, Vers. ii. p.
122.
1869. Pecopteris silesiacus, Schimper, Trait. pal. vég. Vol. i. p. 517.
— Cyathocarpus dentatus, Weiss, Flora der jüngst. Stk. und Roth. p.
86.
1877. Senftenbergia plumosa, Stur, Culm Flora, ii. p. 187 (293).
— S. dentata, ibid.
1886. Dactylotheca plumosa, Kidston, Cat. Palaeozoic Plants, p. 128.
1888. Dactylotheca dentata, Zeiller, Flor. Valenc. Pls. xxvi.–xxviii.
For a fuller synonymy reference should be made to Kidston’s account of
this species[1017], from which the above list is compiled. The large fronds of
this species are tri- or quadripinnate. The pinnules vary much in shape and
size and in degree of lobing, according to their position on the frond (fig.
293). The primary pinnae are subtended by two Aphlebiae (fig. 293, A)
appressed to the rachis, like the delicate leaves of the recent fern
Teratophyllum aculeatum (see page 301). The sporangia (0·5–0·65) are oval
and exannulate and are attached parallel to the lateral veins; they may
occupy the whole of the space between the midrib and the edge of the
pinnules. This species occurs in the Upper, Middle, and Lower Coal-
Measures of Britain, reaching its maximum in the Upper Coal-Measures.
The aphlebiae undoubtedly served to protect the young fronds, as shown by
a specimen figured by Kidston (fig. 293, B); they may also have served
other purposes, as suggested by the above comparison with Teratophyllum,
in the mature frond. Lindley and Hutton regarded the aphlebiae as leaves of
a fern climbing up the rachis; which they named Schizopteris adnascens, a
confusion similar to that already mentioned in the description of Hemitelia
capensis (see p. 304).
1836. Aspidites caudatus, Goeppert, Syst. fil. foss. p. 363.
1838. Steffensia silesiaca, Presl, in Sternberg, Flor. Vorwelt, Vers. ii. p.
122.
1869. Pecopteris silesiacus, Schimper, Trait. pal. vég. Vol. i. p. 517.
— Cyathocarpus dentatus, Weiss, Flora der jüngst. Stk. und Roth. p.
86.
1877. Senftenbergia plumosa, Stur, Culm Flora, ii. p. 187 (293).
— S. dentata, ibid.
1886. Dactylotheca plumosa, Kidston, Cat. Palaeozoic Plants, p. 128.
1888. Dactylotheca dentata, Zeiller, Flor. Valenc. Pls. xxvi.–xxviii.
For a fuller synonymy reference should be made to Kidston’s account of
this species[1017], from which the above list is compiled. The large fronds of
this species are tri- or quadripinnate. The pinnules vary much in shape and
size and in degree of lobing, according to their position on the frond (fig.
293). The primary pinnae are subtended by two Aphlebiae (fig. 293, A)
appressed to the rachis, like the delicate leaves of the recent fern
Teratophyllum aculeatum (see page 301). The sporangia (0·5–0·65) are oval
and exannulate and are attached parallel to the lateral veins; they may
occupy the whole of the space between the midrib and the edge of the
pinnules. This species occurs in the Upper, Middle, and Lower Coal-
Measures of Britain, reaching its maximum in the Upper Coal-Measures.
The aphlebiae undoubtedly served to protect the young fronds, as shown by
a specimen figured by Kidston (fig. 293, B); they may also have served
other purposes, as suggested by the above comparison with Teratophyllum,
in the mature frond. Lindley and Hutton regarded the aphlebiae as leaves of
a fern climbing up the rachis; which they named Schizopteris adnascens, a
confusion similar to that already mentioned in the description of Hemitelia
capensis (see p. 304).
Page 448
Fig. 292. Dactylotheca plumosa. (After Kidston. Slightly reduced.)
Page 449
Fig. 293. Dactylotheca plumosa: A. Rachis with Aphlebiae. B, a, young pinnae circinately
folded. (After Kidston. A, B, ⅘ nat. size.)
Renaultia.
This name was proposed by Zeiller[1018] for Upper Carboniferous fertile
pinnae of the Sphenopteroid type, bearing ovoid sporangia either singly or
in marginal groups of 2 to 5 at the ends of the veins. The appearance of the
apical cells occasionally suggests the presence of a rudimentary annulus.
Kidston has recorded this type of fructification in Britain[1019]. Stur describes
fertile pinnules of the same type under the generic name Hapalopteris[1020].
Zeilleria.
folded. (After Kidston. A, B, ⅘ nat. size.)
Renaultia.
This name was proposed by Zeiller[1018] for Upper Carboniferous fertile
pinnae of the Sphenopteroid type, bearing ovoid sporangia either singly or
in marginal groups of 2 to 5 at the ends of the veins. The appearance of the
apical cells occasionally suggests the presence of a rudimentary annulus.
Kidston has recorded this type of fructification in Britain[1019]. Stur describes
fertile pinnules of the same type under the generic name Hapalopteris[1020].
Zeilleria.
Page 450
This genus was founded by Kidston[1021] for fertile pinnae of a very
delicate fern, Zeilleria delicatula (Sternb.) characterised by filiform
ultimate segments bearing an indusium-like body, spherical when immature
and splitting at maturity into four small valves. Kidston, in his earlier paper,
compared the species with recent Hymenophyllaceae. In the same genus he
includes Z. avoldensis[1022] (Stur) assigned by Stur to Calymmatotheca, a
genus described by some authors as characterised by groups of radially
elongated sporangia at the tips of the pinnules; these supposed sporangia are
now known to be the valves of an indusium-like organ or cupule, as Stur
asserted. There can be little doubt that the fertile fronds placed in
Calymmatotheca and in Zeilleria were borne by Pteridosperms.
Urnatopteris.
The Upper Carboniferous fronds of a delicate Sphenopteris habit, to
which this name was assigned by Kidston[1023], were described by him as
Eusphenopteris tenella (Brongn.)[1024] and compared with
Hymenophyllaceae; subsequently Kidston expressed the opinion that
Urnatopteris may be a Marattiaceous fern, as Williamson[1025] believed; he
has since suggested that the sporangia are the microsporangia of a
Pteridosperm[1026]. The sterile and fertile pinnae differ in the absence of a
lamina in the latter. The sporangia (or microsporangia) are characterised by
a poricidal dehiscence.
The records from strata higher in the geological series than the Permian,
disregarding many of doubtful value, afford ample testimony to the
existence of Marattiaceae in Upper Triassic and Rhaetic floras.
Marattiopsis.
The generic name Danaeopsis was applied by Heer[1027] to an Upper
Triassic fern, previously described by Presl as Taeniopteris marantacea. A
splendid specimen from the Keuper of Stuttgart is figured in Schimper’s
Atlas[1028] showing the pinnate habit of the frond and the broadly linear
segments, 25 cm. × 3·5 cm., bearing rows of contiguous sporangia. The
large pinnules have a strong midrib giving off curved and forked lateral
veins. Presl’s species may most appropriately be included in the genus
Marattiopsis. A specimen of M. marantacea described by Leuthardt[1029] as
Danaeopsis marantacea from the Upper Trias of Basel shows a peculiarity
delicate fern, Zeilleria delicatula (Sternb.) characterised by filiform
ultimate segments bearing an indusium-like body, spherical when immature
and splitting at maturity into four small valves. Kidston, in his earlier paper,
compared the species with recent Hymenophyllaceae. In the same genus he
includes Z. avoldensis[1022] (Stur) assigned by Stur to Calymmatotheca, a
genus described by some authors as characterised by groups of radially
elongated sporangia at the tips of the pinnules; these supposed sporangia are
now known to be the valves of an indusium-like organ or cupule, as Stur
asserted. There can be little doubt that the fertile fronds placed in
Calymmatotheca and in Zeilleria were borne by Pteridosperms.
Urnatopteris.
The Upper Carboniferous fronds of a delicate Sphenopteris habit, to
which this name was assigned by Kidston[1023], were described by him as
Eusphenopteris tenella (Brongn.)[1024] and compared with
Hymenophyllaceae; subsequently Kidston expressed the opinion that
Urnatopteris may be a Marattiaceous fern, as Williamson[1025] believed; he
has since suggested that the sporangia are the microsporangia of a
Pteridosperm[1026]. The sterile and fertile pinnae differ in the absence of a
lamina in the latter. The sporangia (or microsporangia) are characterised by
a poricidal dehiscence.
The records from strata higher in the geological series than the Permian,
disregarding many of doubtful value, afford ample testimony to the
existence of Marattiaceae in Upper Triassic and Rhaetic floras.
Marattiopsis.
The generic name Danaeopsis was applied by Heer[1027] to an Upper
Triassic fern, previously described by Presl as Taeniopteris marantacea. A
splendid specimen from the Keuper of Stuttgart is figured in Schimper’s
Atlas[1028] showing the pinnate habit of the frond and the broadly linear
segments, 25 cm. × 3·5 cm., bearing rows of contiguous sporangia. The
large pinnules have a strong midrib giving off curved and forked lateral
veins. Presl’s species may most appropriately be included in the genus
Marattiopsis. A specimen of M. marantacea described by Leuthardt[1029] as
Danaeopsis marantacea from the Upper Trias of Basel shows a peculiarity
Page 451
in the venation; the lateral veins often fork near their origin, as noticed by
other authors, but each vein forks a second time near the edge of the lamina
and the two arms converge, forming a series of intramarginal loops (fig.
265, B).
Marattiopsis Muensteri (Goepp.). Fig. 245, D, E.
This widely spread Rhaetic plant affords the best example of a post-
Permian species which may be accepted as an authentic record of fossil
Marattiaceae. Various generic names have been used for this species;
Goeppert originally described the plant as Taeniopteris Muensteri[1030];
Schimper[1031] proposed the name Marattiopsis, and Schenk[1032] substituted
Angiopteris on the ground that the fertile pinnules resemble that genus
rather than Marattia. Marattiopsis, if interpreted as indicating a family
resemblance rather than special affinity to the genus Marattia, would seem
to be the more appropriate designation.
This species has been figured by several authors and in many instances
with fertile pinnules; the best illustrations are those published by Zeiller[1033]
in his monograph of Tonkin plants.
The pinnate fronds are characterised by a broad rachis bearing sessile broadly linear pinnules
rounded at the base, obtusely pointed at the apex, reaching a length of 15–20 cm. and a breadth
of 12–35 mm. From a well-marked midrib are given off secondary veins dichotomously branched
close to their origin. The linear synangia near the ends of the veins contain two rows of
sporangial compartments and open as two valves as in Marattia. (Cf. fig. 245, A, p. 320.)
This species occurs in the Rhaetic beds of Scania, Franconia, and Tonkin.
A similar type is figured by Fontaine from Jurassic beds in California as
Angiopteridium californicum[1034], and Bartholin[1035] and Moeller[1036] record
M. Muensteri from the Lias of Bornholm. Schenk’s species from China[1037],
Angiopteris Richthofeni, is a closely allied species, and a similar form is
recorded from Jurassic and Caucasian strata[1038]. The microscopical
examination by Nathorst[1039] of a group of spores from a synangium of M.
Muensteri shows that they resemble those of recent Marattiaceae.
• • • • •
From the Upper Triassic plant beds of Lunz, Stur has included several
species of ferns in the Marattiaceae, and of these Krasser[1040] has recently
published full diagnoses but unfortunately without illustrations. In addition
other authors, but each vein forks a second time near the edge of the lamina
and the two arms converge, forming a series of intramarginal loops (fig.
265, B).
Marattiopsis Muensteri (Goepp.). Fig. 245, D, E.
This widely spread Rhaetic plant affords the best example of a post-
Permian species which may be accepted as an authentic record of fossil
Marattiaceae. Various generic names have been used for this species;
Goeppert originally described the plant as Taeniopteris Muensteri[1030];
Schimper[1031] proposed the name Marattiopsis, and Schenk[1032] substituted
Angiopteris on the ground that the fertile pinnules resemble that genus
rather than Marattia. Marattiopsis, if interpreted as indicating a family
resemblance rather than special affinity to the genus Marattia, would seem
to be the more appropriate designation.
This species has been figured by several authors and in many instances
with fertile pinnules; the best illustrations are those published by Zeiller[1033]
in his monograph of Tonkin plants.
The pinnate fronds are characterised by a broad rachis bearing sessile broadly linear pinnules
rounded at the base, obtusely pointed at the apex, reaching a length of 15–20 cm. and a breadth
of 12–35 mm. From a well-marked midrib are given off secondary veins dichotomously branched
close to their origin. The linear synangia near the ends of the veins contain two rows of
sporangial compartments and open as two valves as in Marattia. (Cf. fig. 245, A, p. 320.)
This species occurs in the Rhaetic beds of Scania, Franconia, and Tonkin.
A similar type is figured by Fontaine from Jurassic beds in California as
Angiopteridium californicum[1034], and Bartholin[1035] and Moeller[1036] record
M. Muensteri from the Lias of Bornholm. Schenk’s species from China[1037],
Angiopteris Richthofeni, is a closely allied species, and a similar form is
recorded from Jurassic and Caucasian strata[1038]. The microscopical
examination by Nathorst[1039] of a group of spores from a synangium of M.
Muensteri shows that they resemble those of recent Marattiaceae.
• • • • •
From the Upper Triassic plant beds of Lunz, Stur has included several
species of ferns in the Marattiaceae, and of these Krasser[1040] has recently
published full diagnoses but unfortunately without illustrations. In addition
Page 452
to Marattiopsis marantacea (Presl) the list includes species referred to
Coniopteris, to Speirocarpus, a genus founded by Stur, to Oligocarpia,
Asterotheca, and Bernouillia (Heer).
As already pointed out, some at least of these Austrian ferns are more
probably Osmundaceous than Marattiaceous.
Danaeopsis
Danaeopsis Hughesi, Feistmantel.
The pinnate fronds described by Feistmantel[1041] from the Middle
Gondwana rocks of India and recorded from Rhaetic strata in South
Africa[1042], China[1043], and Tonkin[1044], may belong to a member of the
Marattiaceae, but no fertile specimens have been described. The close
agreement between the sterile leaves from India and South Africa and the
fertile fronds of Marattiopsis marantacea suggests generic identity.
The Upper Triassic ferns described by Heer, Krasser[1045], and
Leuthardt[1046] as Bernouillia have been referred to the Marattiaceae, but
without trustworthy evidence in favour of this affinity.
The large leaves, 70 cm. long and 7 cm. broad, described by Zigno[1047]
from the Jurassic of Italy as Danaeites Heeri, are probably Cycadean. The
Polish Jurassic species Danaea microphylla[1048] is a more satisfactory
record.
Coniopteris, to Speirocarpus, a genus founded by Stur, to Oligocarpia,
Asterotheca, and Bernouillia (Heer).
As already pointed out, some at least of these Austrian ferns are more
probably Osmundaceous than Marattiaceous.
Danaeopsis
Danaeopsis Hughesi, Feistmantel.
The pinnate fronds described by Feistmantel[1041] from the Middle
Gondwana rocks of India and recorded from Rhaetic strata in South
Africa[1042], China[1043], and Tonkin[1044], may belong to a member of the
Marattiaceae, but no fertile specimens have been described. The close
agreement between the sterile leaves from India and South Africa and the
fertile fronds of Marattiopsis marantacea suggests generic identity.
The Upper Triassic ferns described by Heer, Krasser[1045], and
Leuthardt[1046] as Bernouillia have been referred to the Marattiaceae, but
without trustworthy evidence in favour of this affinity.
The large leaves, 70 cm. long and 7 cm. broad, described by Zigno[1047]
from the Jurassic of Italy as Danaeites Heeri, are probably Cycadean. The
Polish Jurassic species Danaea microphylla[1048] is a more satisfactory
record.
Page 453
Fig. 294.
A, B. Nathorstia angustifolia, Heer. (After Heer. A, nat. size.)
C, D. Sorus of N. latifolia, Nath. (After Nathorst. C, × 12; D, × 45.)
Nathorstia.
This name was instituted by Heer[1049] for pieces of pinnate fronds from
Lower Cretaceous rocks of Greenland. The resemblance of the long
pinnules to the fertile segments of Laccopteris is so close that generic
identity might well be assumed, but it has recently been shown by
Nathorst[1050] that the soral characters justify Heer’s use of a distinctive
name for the Arctic fern. The circular sori arranged in two rows (fig. 294, A,
B) are superficially identical with those of Laccopteris, but consist of
concrescent sporangia forming a circular synangium (fig. 294, C, D) like
those of Kaulfussia and Ptychocarpus. The lighter areas in fig. 294, D,
A, B. Nathorstia angustifolia, Heer. (After Heer. A, nat. size.)
C, D. Sorus of N. latifolia, Nath. (After Nathorst. C, × 12; D, × 45.)
Nathorstia.
This name was instituted by Heer[1049] for pieces of pinnate fronds from
Lower Cretaceous rocks of Greenland. The resemblance of the long
pinnules to the fertile segments of Laccopteris is so close that generic
identity might well be assumed, but it has recently been shown by
Nathorst[1050] that the soral characters justify Heer’s use of a distinctive
name for the Arctic fern. The circular sori arranged in two rows (fig. 294, A,
B) are superficially identical with those of Laccopteris, but consist of
concrescent sporangia forming a circular synangium (fig. 294, C, D) like
those of Kaulfussia and Ptychocarpus. The lighter areas in fig. 294, D,
Page 454
represent the sporangia: fig. C shows the radial disposition of the numerous
sporangial compartments round a central receptacle. From a stout midrib
lateral veins arise at right angles, but their distal terminations are not
preserved. It is probable, as Nathorst suggests, that Bayer’s[1051] species
Drynaria fascia from the Lower Cretaceous rocks of Bohemia should be
referred to Heer’s genus. In the absence of well-preserved sori it would be
exceedingly difficult, or even impossible, to distinguish between pinnules
of Laccopteris and Nathorstia.
A Tertiary species, Marattia Hookeri (fig. 261, C, p. 350), described by
Gardner and Ettingshausen[1052] from the Eocene beds of the Isle of Wight is
referred by them to the Marattiaceae because of a resemblance of the sterile
pinnae to those of M. Kaulfussii; but this is insufficient evidence of
relationship.
sporangial compartments round a central receptacle. From a stout midrib
lateral veins arise at right angles, but their distal terminations are not
preserved. It is probable, as Nathorst suggests, that Bayer’s[1051] species
Drynaria fascia from the Lower Cretaceous rocks of Bohemia should be
referred to Heer’s genus. In the absence of well-preserved sori it would be
exceedingly difficult, or even impossible, to distinguish between pinnules
of Laccopteris and Nathorstia.
A Tertiary species, Marattia Hookeri (fig. 261, C, p. 350), described by
Gardner and Ettingshausen[1052] from the Eocene beds of the Isle of Wight is
referred by them to the Marattiaceae because of a resemblance of the sterile
pinnae to those of M. Kaulfussii; but this is insufficient evidence of
relationship.
Page 455
Page 456
CHAPTER XXIII.
Psaronieae.
This family name, first suggested by Unger, may be conveniently adopted
for the numerous species of petrified tree-fern stems characteristic of the
Lower Permian and Upper Carboniferous strata. In his monograph Über die
Staarsteine published in 1854, Stenzel[1053] referred to the Psaronieae as a
special subdivision of the Filices most nearly allied to the Polypodiaceae.
There is now a consensus of opinion in favour of including Psaronius in the
Marattiales, or at least of regarding the genus as more closely allied to the
Marattiaceae than to any other family. While admitting that the balance of
evidence is in favour of this view, it is probably wiser to retain the
distinctive term Psaronieae on the ground that species of Psaronius differ in
several respects from any recent ferns, and because of our comparative
ignorance in regard to the nature of the fructification.
Psaronius.
This generic name was proposed by Cotta in his classic work Die
Dendrolithen[1054]. The stems so named, formerly included by Sprengel[1055]
in the genus Endogenites, had long been familiar as petrified fossils. Most
of the specimens described by the earlier writers were obtained from Lower
Permian rocks in the neighbourhood of Chemnitz, Saxony. The mottled
appearance presented by their polished surfaces is said to have given rise to
the appellation Staarsteine (starling stones), a term expressing a
resemblance, more or less remote, to a starling’s breast. It has been
suggested that this word is a corruption of Stern Steine or star stones[1056], a
descriptive term suggested by the stellate arrangement of the vascular
strands in transverse sections of the roots. Parkinson[1057], in his Organic
Remains of a former World, speaks of these stems as starry stones. The
history of our knowledge prior to 1854 is summarised by Stenzel. At first
compared with corals or the stems of sea-lilies, Psaronii were recognised by
Sprengel, who first used a lens in the examination of the fossils, as fern
Psaronieae.
This family name, first suggested by Unger, may be conveniently adopted
for the numerous species of petrified tree-fern stems characteristic of the
Lower Permian and Upper Carboniferous strata. In his monograph Über die
Staarsteine published in 1854, Stenzel[1053] referred to the Psaronieae as a
special subdivision of the Filices most nearly allied to the Polypodiaceae.
There is now a consensus of opinion in favour of including Psaronius in the
Marattiales, or at least of regarding the genus as more closely allied to the
Marattiaceae than to any other family. While admitting that the balance of
evidence is in favour of this view, it is probably wiser to retain the
distinctive term Psaronieae on the ground that species of Psaronius differ in
several respects from any recent ferns, and because of our comparative
ignorance in regard to the nature of the fructification.
Psaronius.
This generic name was proposed by Cotta in his classic work Die
Dendrolithen[1054]. The stems so named, formerly included by Sprengel[1055]
in the genus Endogenites, had long been familiar as petrified fossils. Most
of the specimens described by the earlier writers were obtained from Lower
Permian rocks in the neighbourhood of Chemnitz, Saxony. The mottled
appearance presented by their polished surfaces is said to have given rise to
the appellation Staarsteine (starling stones), a term expressing a
resemblance, more or less remote, to a starling’s breast. It has been
suggested that this word is a corruption of Stern Steine or star stones[1056], a
descriptive term suggested by the stellate arrangement of the vascular
strands in transverse sections of the roots. Parkinson[1057], in his Organic
Remains of a former World, speaks of these stems as starry stones. The
history of our knowledge prior to 1854 is summarised by Stenzel. At first
compared with corals or the stems of sea-lilies, Psaronii were recognised by
Sprengel, who first used a lens in the examination of the fossils, as fern
Page 457
stems most nearly allied to those of recent Cyatheaceae. By other authors,
e.g. Schlotheim and Sternberg, they were referred to Palms, and by
Brongniart considered to be the lower portions of Lycopodiaceous
(Lepidodendron) stems. Corda and many subsequent authors selected the
Marattiaceae as the most closely allied family among existing plants.
Psaronius is represented by specimens obtained from the Lower Permian
of Saxony and Upper Carboniferous rocks in Central France, also from
Bohemia, Brazil and North America. As yet a few fragments only have been
found in the English Coal-Measures. The genus was recognised by
Williamson[1058] who described the roots and a small piece of the vascular
tissue of a stem which he called P. Renaulti, and this type has since been
more fully described by Scott[1059]. The roots of another species have been
described by Butterworth[1060] as P. Cromptonensis.
It was pointed out in the account of Lepidodendron that several generic
names have been used for the same type of stem in different states of
preservation; in Psaronius accidents of fossilisation have been responsible
for a similar confusion in nomenclature. The name Psaronius is applied to
petrified specimens which, as a rule, lack external features. Casts or
impressions of Palaeozoic tree-fern stems provided with leaf-scars are
described as species of Caulopteris, Megaphyton, and less commonly as
Ptychopteris (figs. 297–299). The first name is applied to stems exhibiting
spirally disposed leaf-scars like those of recent tree-ferns; in Megaphyton
the scars are distichously arranged, in two rows, while Ptychopteris is
applied to decorticated stems. These terms are used for stems belonging to
one generic type and possessing the structure of Psaronius stems.
e.g. Schlotheim and Sternberg, they were referred to Palms, and by
Brongniart considered to be the lower portions of Lycopodiaceous
(Lepidodendron) stems. Corda and many subsequent authors selected the
Marattiaceae as the most closely allied family among existing plants.
Psaronius is represented by specimens obtained from the Lower Permian
of Saxony and Upper Carboniferous rocks in Central France, also from
Bohemia, Brazil and North America. As yet a few fragments only have been
found in the English Coal-Measures. The genus was recognised by
Williamson[1058] who described the roots and a small piece of the vascular
tissue of a stem which he called P. Renaulti, and this type has since been
more fully described by Scott[1059]. The roots of another species have been
described by Butterworth[1060] as P. Cromptonensis.
It was pointed out in the account of Lepidodendron that several generic
names have been used for the same type of stem in different states of
preservation; in Psaronius accidents of fossilisation have been responsible
for a similar confusion in nomenclature. The name Psaronius is applied to
petrified specimens which, as a rule, lack external features. Casts or
impressions of Palaeozoic tree-fern stems provided with leaf-scars are
described as species of Caulopteris, Megaphyton, and less commonly as
Ptychopteris (figs. 297–299). The first name is applied to stems exhibiting
spirally disposed leaf-scars like those of recent tree-ferns; in Megaphyton
the scars are distichously arranged, in two rows, while Ptychopteris is
applied to decorticated stems. These terms are used for stems belonging to
one generic type and possessing the structure of Psaronius stems.
Page 458
Fig. 295. Psaronius stem with roots. (Much reduced. After Grand’Eury.)
The researches of Grand’Eury[1061] led to the discovery that certain
Psaronius stems bore fronds of the Pecopteris type some of which bore sori
of the Asterotheca or Scolecopteris type. The same author[1062] has also
contributed many interesting facts, obtained by an examination of the
relation of Psaronius stems to the sediments of French Coal-fields in which
they occur, in regard to habitat and manner of growth. The specimen
represented in fig. 295 shows a portion of a Psaronius stem, the upper part
of which illustrates the Caulopteris state of preservation, while the lower
part is covered by a mass of roots. It is probable, as Rudolph[1063] suggests,
that this rich development of roots, which gives to an old Psaronius stem
the appearance of an elongated cone, may have served an important
mechanical purpose analogous to the secondary thickening in a Dicotyledon
or a Conifer. A specimen of Psaronius Cottai in the Hofmuseum, Vienna, is
cited in illustration of the enormous breadth of the root-system: the radii of
the stem proper and of the encasing cylinder of roots bear the ratio 17 to
165. The comparatively frequent occurrence of a lacunar cortex in the roots
points to the growth of the stems in swampy ground, a conclusion in
harmony with the evidence afforded by the anatomical features of many
other Palaeozoic genera.
The researches of Grand’Eury[1061] led to the discovery that certain
Psaronius stems bore fronds of the Pecopteris type some of which bore sori
of the Asterotheca or Scolecopteris type. The same author[1062] has also
contributed many interesting facts, obtained by an examination of the
relation of Psaronius stems to the sediments of French Coal-fields in which
they occur, in regard to habitat and manner of growth. The specimen
represented in fig. 295 shows a portion of a Psaronius stem, the upper part
of which illustrates the Caulopteris state of preservation, while the lower
part is covered by a mass of roots. It is probable, as Rudolph[1063] suggests,
that this rich development of roots, which gives to an old Psaronius stem
the appearance of an elongated cone, may have served an important
mechanical purpose analogous to the secondary thickening in a Dicotyledon
or a Conifer. A specimen of Psaronius Cottai in the Hofmuseum, Vienna, is
cited in illustration of the enormous breadth of the root-system: the radii of
the stem proper and of the encasing cylinder of roots bear the ratio 17 to
165. The comparatively frequent occurrence of a lacunar cortex in the roots
points to the growth of the stems in swampy ground, a conclusion in
harmony with the evidence afforded by the anatomical features of many
other Palaeozoic genera.
Page 459
• • • • •
Psaronius may be briefly defined as follows:—
Tree-fern stems, occasionally reaching a height of 50 feet or more, closely resembling in habit
recent tree ferns, but exhibiting in the structure and arrangement of the vascular system a close
agreement with recent Marattiaceae. Leaves, in such cases where a connexion between fronds
and stems is known, large and highly compound and of the Pecopteris type, borne in more or less
crowded spirals (Psaronius polystichi), in four rows (P. tetrastichi), or in two opposite rows (P.
distichi). Leaves deciduous, leaving a clearly defined oval scar containing the impression of the
leaf-trace in the form of an open U, or a closed oval with a small inverted V-shaped band a short
distance below the upper end of the long axis of the oval (figs. 297, 298); in Megaphyton the
alternate scars of the two opposite series are larger and characterised by a different form of
meristele. The surface of the cortex below the leaf-scars occasionally shows impressions of pits
similar to the lenticel-like organs on recent Tree-fern stems. The central region of the stem is
occupied by a complex system of concentrically disposed steles (dictyosteles), which in
transverse section present the appearance of flat or curved bands varying in extent and in degree
of curvature. The vascular bands consist of xylem surrounded by a narrow zone of phloem; the
xylem is composed either exclusively of tracheae or of tracheae and parenchyma; the protoxylem
in the one instance in which it has been clearly recognised is endarch[1064]. The steles are
embedded in parenchymatous tissue and in some species are associated with mechanical tissue
(e.g. P. infarctus, fig. 296, A, B). The central or vascular region of the stem may be surrounded
externally by a cylinder of mechanical tissue interrupted by outgoing leaf-traces and adventitious
roots. The leaf-traces arise as single bundles from an internal stelar band and pursue an obliquely
radial course towards the outside, eventually anastomosing with peripheral cauline steles, which
in some species form with the leaf-traces the outermost zone of the vascular region. The leaf-
traces have the form of loops which pass into the petioles as V-shaped meristeles or closed oval
cylinders. As a leaf-trace passes out compensating strands occupy the foliar gap.
The vascular region is surrounded by a parenchymatous cortex, which in younger plants, or in
the apical region of an older plant, forms the surface of the stem to which the leaf-stalks are
attached. From the peripheral steles, or from the more external bands of the vascular network,
roots are given off which pass in a sinuous vertical course through the cortex, appearing on the
surface between the leaf-bases. In older stems, after leaf-fall, the tissue immediately external to
the vascular region produces secondary parenchyma with which the roots become intimately
associated by their outermost cells. As a result of the secondary cortical development and the
gradual increase in the number of roots invading the cortical tissue from above, the stem is
enclosed by a cylinder of roots and associated parenchymatous tissue of secondary origin. In still
older portions of a stem the more external roots are free from the stem-cortex and form a thick
felted mantle, which increases in thickness towards the base of the tree.
The roots (fig. 296, E) are polyarch, 5–10 groups of xylem alternating with strands of phloem,
and similar in structure to those of recent species of Marattia and Angiopteris; the stele is
enclosed by an inner cortex of compact or lacunar tissue containing secretory sacs, and this is
surrounded by a cylinder of mechanical tissue. In one or two instances secondary xylem has been
observed wholly or partially enclosing the root-stele[1065].
Psaronius may be briefly defined as follows:—
Tree-fern stems, occasionally reaching a height of 50 feet or more, closely resembling in habit
recent tree ferns, but exhibiting in the structure and arrangement of the vascular system a close
agreement with recent Marattiaceae. Leaves, in such cases where a connexion between fronds
and stems is known, large and highly compound and of the Pecopteris type, borne in more or less
crowded spirals (Psaronius polystichi), in four rows (P. tetrastichi), or in two opposite rows (P.
distichi). Leaves deciduous, leaving a clearly defined oval scar containing the impression of the
leaf-trace in the form of an open U, or a closed oval with a small inverted V-shaped band a short
distance below the upper end of the long axis of the oval (figs. 297, 298); in Megaphyton the
alternate scars of the two opposite series are larger and characterised by a different form of
meristele. The surface of the cortex below the leaf-scars occasionally shows impressions of pits
similar to the lenticel-like organs on recent Tree-fern stems. The central region of the stem is
occupied by a complex system of concentrically disposed steles (dictyosteles), which in
transverse section present the appearance of flat or curved bands varying in extent and in degree
of curvature. The vascular bands consist of xylem surrounded by a narrow zone of phloem; the
xylem is composed either exclusively of tracheae or of tracheae and parenchyma; the protoxylem
in the one instance in which it has been clearly recognised is endarch[1064]. The steles are
embedded in parenchymatous tissue and in some species are associated with mechanical tissue
(e.g. P. infarctus, fig. 296, A, B). The central or vascular region of the stem may be surrounded
externally by a cylinder of mechanical tissue interrupted by outgoing leaf-traces and adventitious
roots. The leaf-traces arise as single bundles from an internal stelar band and pursue an obliquely
radial course towards the outside, eventually anastomosing with peripheral cauline steles, which
in some species form with the leaf-traces the outermost zone of the vascular region. The leaf-
traces have the form of loops which pass into the petioles as V-shaped meristeles or closed oval
cylinders. As a leaf-trace passes out compensating strands occupy the foliar gap.
The vascular region is surrounded by a parenchymatous cortex, which in younger plants, or in
the apical region of an older plant, forms the surface of the stem to which the leaf-stalks are
attached. From the peripheral steles, or from the more external bands of the vascular network,
roots are given off which pass in a sinuous vertical course through the cortex, appearing on the
surface between the leaf-bases. In older stems, after leaf-fall, the tissue immediately external to
the vascular region produces secondary parenchyma with which the roots become intimately
associated by their outermost cells. As a result of the secondary cortical development and the
gradual increase in the number of roots invading the cortical tissue from above, the stem is
enclosed by a cylinder of roots and associated parenchymatous tissue of secondary origin. In still
older portions of a stem the more external roots are free from the stem-cortex and form a thick
felted mantle, which increases in thickness towards the base of the tree.
The roots (fig. 296, E) are polyarch, 5–10 groups of xylem alternating with strands of phloem,
and similar in structure to those of recent species of Marattia and Angiopteris; the stele is
enclosed by an inner cortex of compact or lacunar tissue containing secretory sacs, and this is
surrounded by a cylinder of mechanical tissue. In one or two instances secondary xylem has been
observed wholly or partially enclosing the root-stele[1065].
Page 460
Fig. 296.
A. Psaronius infarctus (P, peripheral steles; L, leaf-traces).
B. P. infarctus, longitudinal tangential section through the peripheral region of the
stem.
C. P. coalescens.
D. P. musaeformis.
E. P. asterolithus (root).
(A—C, E, after Zeiller; D, after Stenzel.)
Our knowledge of the anatomy of Psaronius is based largely on the
investigations of Stenzel considerably extended by Zeiller’s more intensive
studies and, more recently, by the later work of Stenzel[1066] and that of
Rudolph. A striking fact, which has led to various suggestions, is that in a
A. Psaronius infarctus (P, peripheral steles; L, leaf-traces).
B. P. infarctus, longitudinal tangential section through the peripheral region of the
stem.
C. P. coalescens.
D. P. musaeformis.
E. P. asterolithus (root).
(A—C, E, after Zeiller; D, after Stenzel.)
Our knowledge of the anatomy of Psaronius is based largely on the
investigations of Stenzel considerably extended by Zeiller’s more intensive
studies and, more recently, by the later work of Stenzel[1066] and that of
Rudolph. A striking fact, which has led to various suggestions, is that in a
Page 461
transverse section of a Psaronius stem with its encasing cylinder of roots no
signs of leaf-traces are met with in the root-region. If the roots simply
penetrated the cortex, as in some recent species of Lycopodium (fig. 125, A)
or as in Angiopteris, we should expect to find leaf-traces in the outer region
(root-cylinder) of Psaronius stems. An explanation of the absence of leaf-
traces which was suggested by Stenzel, is that the cortical zone formed a
comparatively narrow band in the young leaf-covered stem; after leaf-fall it
became the seat of active growth in its inner layers and so produced a
constantly widening zone of secondary parenchyma, which pushed the
superficial cortical tissue with the leaf-bases or leaf-scars farther out until it
was exfoliated. Farmer and Hill[1067] find it difficult to accept this
explanation; but, as Rudolph shows, the radial arrangement of the cortical
cells between the adventitious roots and their elongation in a radial
direction are arguments in support of the secondary nature of the cortical
zone.
In sections of the adventitious roots of Psaronius Renaulti figured by
Williamson[1068], the spaces between the cylindrical roots are partially
occupied by cell-filaments which, at first sight, suggest root-hairs; it may
well be, as Rudolph suggests, that these felted hairs represent the outermost
and looser part of the growing secondary cortex which gradually passes into
the covering mass of free extra-cortical roots.
As Stenzel[1069] has shown, slender stems of Zygopteris (= Ankyropteris)
are occasionally met with growing through the web of Psaronius roots.
Psaronius infarctus Unger. Fig. 296, A, B.
This species, which Zeiller[1070] has investigated from sections of Unger’s
material, illustrates a type in which the vascular tissue is very richly
developed and forms crowded concentric series of curved plates associated,
in the more peripheral series, with bands of mechanical tissue. The
outermost part of the vascular region consists of (i) a series of loops or
variously curved bands of conducting tissue representing leaf-traces at
different stages in their outward course, (ii) a series of similar vascular
strands (peripheral steles of Zeiller) confined to the stem (cauline) and from
which roots are given off, and (iii) bands of mechanical tissue associated
with the leaf-traces and peripheral steles. The peripheral steles (fig. 296, A,
signs of leaf-traces are met with in the root-region. If the roots simply
penetrated the cortex, as in some recent species of Lycopodium (fig. 125, A)
or as in Angiopteris, we should expect to find leaf-traces in the outer region
(root-cylinder) of Psaronius stems. An explanation of the absence of leaf-
traces which was suggested by Stenzel, is that the cortical zone formed a
comparatively narrow band in the young leaf-covered stem; after leaf-fall it
became the seat of active growth in its inner layers and so produced a
constantly widening zone of secondary parenchyma, which pushed the
superficial cortical tissue with the leaf-bases or leaf-scars farther out until it
was exfoliated. Farmer and Hill[1067] find it difficult to accept this
explanation; but, as Rudolph shows, the radial arrangement of the cortical
cells between the adventitious roots and their elongation in a radial
direction are arguments in support of the secondary nature of the cortical
zone.
In sections of the adventitious roots of Psaronius Renaulti figured by
Williamson[1068], the spaces between the cylindrical roots are partially
occupied by cell-filaments which, at first sight, suggest root-hairs; it may
well be, as Rudolph suggests, that these felted hairs represent the outermost
and looser part of the growing secondary cortex which gradually passes into
the covering mass of free extra-cortical roots.
As Stenzel[1069] has shown, slender stems of Zygopteris (= Ankyropteris)
are occasionally met with growing through the web of Psaronius roots.
Psaronius infarctus Unger. Fig. 296, A, B.
This species, which Zeiller[1070] has investigated from sections of Unger’s
material, illustrates a type in which the vascular tissue is very richly
developed and forms crowded concentric series of curved plates associated,
in the more peripheral series, with bands of mechanical tissue. The
outermost part of the vascular region consists of (i) a series of loops or
variously curved bands of conducting tissue representing leaf-traces at
different stages in their outward course, (ii) a series of similar vascular
strands (peripheral steles of Zeiller) confined to the stem (cauline) and from
which roots are given off, and (iii) bands of mechanical tissue associated
with the leaf-traces and peripheral steles. The peripheral steles (fig. 296, A,
Page 462
B, p) form anastomoses with the leaf-traces and contribute to their
formation.
The form of some of the vascular bands in the section of Psaronius
infarctus shown in fig. 296, A, illustrates the occasional anastomosing of
one dictyostele with another: the different degrees of looping of other bands
represent stages in the giving off of leaf-traces which eventually pass out as
V-shaped meristeles. Beyond the leaf-traces and sclerenchymatous bands
the section consists of transverse sections of adventitious roots.
The surface-features of Psaronius infarctus are probably represented, as
Zeiller points out, by the cast described by Lesquereux as Caulopteris
peltigera (fig. 298, A).
Fig. 297. Pecopteris Sterzeli: a, pinnule. (After Renault and Zeiller. ¹⁄₁₁ nat. size.)
The Psaronius shown in fig. 297 is one of the few examples illustrating
the connexion between fronds and stem. The leaf (Pecopteris Sterzeli Zeill.
and Ren.[1071] is quadripinnate and is described as reaching a length of at
formation.
The form of some of the vascular bands in the section of Psaronius
infarctus shown in fig. 296, A, illustrates the occasional anastomosing of
one dictyostele with another: the different degrees of looping of other bands
represent stages in the giving off of leaf-traces which eventually pass out as
V-shaped meristeles. Beyond the leaf-traces and sclerenchymatous bands
the section consists of transverse sections of adventitious roots.
The surface-features of Psaronius infarctus are probably represented, as
Zeiller points out, by the cast described by Lesquereux as Caulopteris
peltigera (fig. 298, A).
Fig. 297. Pecopteris Sterzeli: a, pinnule. (After Renault and Zeiller. ¹⁄₁₁ nat. size.)
The Psaronius shown in fig. 297 is one of the few examples illustrating
the connexion between fronds and stem. The leaf (Pecopteris Sterzeli Zeill.
and Ren.[1071] is quadripinnate and is described as reaching a length of at
Page 463
least 3 metres; the ultimate segments are entire or lobed. The stem is
characterised by elliptical scars, 6–8 cm. x 3·5–4 cm., with leaf-traces like
those in Caulopteris peltigera. The fronds of Pecopteris Pluckeneti, a
Pteridosperm, bear a very close resemblance to those of P. Sterzeli, which
are as yet known only in a sterile state.
• • • • •
Psaronius brasiliensis Unger, a species founded by Unger on a piece of
silicified stem acquired by Martius in Brazil and now in the Rio Museum, is
a good example of a tetrastichous species. Solms-Laubach[1072] has recently
told the history of this type, which is represented by sections, cut from the
Rio stem, in several European collections. A well-preserved section in the
British Museum is figured by Arber[1073] in his catalogue of the Glossopteris
flora and by other authors. Scott gives a concise description of the species
in his Studies in Fossil Botany[1074]. The roots of P. brasiliensis are stated by
Pelourde[1075] to have a lacunar cortex.
Psaronius musaeformis Corda[1076]. Fig. 296, D.
This species from the Lower Permian of Chemnitz and the Coal-
Measures of Bohemia affords an example of the distichous type in which
the leaves are borne in two rows. The vascular bands, as seen in a section of
the dictyosteles, occur in regular parallel series. The stelar region is
separated from the cylinder of encasing roots by a sclerenchymatous sheath,
broken at intervals where roots pass out from the vascular region.
Psaronius coalescens[1077] (fig. 296, C) illustrates a somewhat different
arrangement of vascular tissue which approaches more closely to the
polycyclic structure characteristic of such recent ferns as Matonia and
Saccoloma. A still closer resemblance to the solenostelic type is seen in
Psaronius Renaulti from the Lower Coal-Measures of England which
Scott[1078] describes as characterised by a single annular stele, interrupted
only by the exit of leaf-traces. As he points out, it is noteworthy that this
species is distinguished by the simplest form of stele met with in the genus;
it is the oldest species and may be regarded as the most primitive
representative of the genus Psaronius so far discovered.
characterised by elliptical scars, 6–8 cm. x 3·5–4 cm., with leaf-traces like
those in Caulopteris peltigera. The fronds of Pecopteris Pluckeneti, a
Pteridosperm, bear a very close resemblance to those of P. Sterzeli, which
are as yet known only in a sterile state.
• • • • •
Psaronius brasiliensis Unger, a species founded by Unger on a piece of
silicified stem acquired by Martius in Brazil and now in the Rio Museum, is
a good example of a tetrastichous species. Solms-Laubach[1072] has recently
told the history of this type, which is represented by sections, cut from the
Rio stem, in several European collections. A well-preserved section in the
British Museum is figured by Arber[1073] in his catalogue of the Glossopteris
flora and by other authors. Scott gives a concise description of the species
in his Studies in Fossil Botany[1074]. The roots of P. brasiliensis are stated by
Pelourde[1075] to have a lacunar cortex.
Psaronius musaeformis Corda[1076]. Fig. 296, D.
This species from the Lower Permian of Chemnitz and the Coal-
Measures of Bohemia affords an example of the distichous type in which
the leaves are borne in two rows. The vascular bands, as seen in a section of
the dictyosteles, occur in regular parallel series. The stelar region is
separated from the cylinder of encasing roots by a sclerenchymatous sheath,
broken at intervals where roots pass out from the vascular region.
Psaronius coalescens[1077] (fig. 296, C) illustrates a somewhat different
arrangement of vascular tissue which approaches more closely to the
polycyclic structure characteristic of such recent ferns as Matonia and
Saccoloma. A still closer resemblance to the solenostelic type is seen in
Psaronius Renaulti from the Lower Coal-Measures of England which
Scott[1078] describes as characterised by a single annular stele, interrupted
only by the exit of leaf-traces. As he points out, it is noteworthy that this
species is distinguished by the simplest form of stele met with in the genus;
it is the oldest species and may be regarded as the most primitive
representative of the genus Psaronius so far discovered.
Page 464
Fig. 298.
A. Caulopteris peltigera.
B. Megaphyton insigne.
(After Grand’Eury.) Much reduced.
Psaronius stems preserved as casts showing surface-features, or in a
decorticated state.
i. Caulopteris.
This generic name was instituted by Lindley and Hutton[1079] for tree-fern
stems from the English Coal-Measures showing circular or oval scars
arranged quincuncially. The vascular tissue of the petiole is represented by a
U-shaped impression on the scar, the ends of the U being incurved, or by a
closed oval ring with a wide-open and inverted V near its upper end. The
surface between the leaf-scars bears the impression of adventitious roots.
Caulopteris is represented, in the Upper Coal-Measures of England, by C.
anglica[1080] Kidst. The species C. peltigera (fig. 298, A), originally
described by Brongniart as Sigillaria, illustrates the closed form of leaf-
trace and, as Zeiller suggests, it is the cast of a Psaronius stem which
possessed a vascular system on the same plan as that of P. infarctus. C.
Saportae[1081] illustrates the open U-shaped type of petiole stele.
Caulopteris peltigera has scars measuring 6–9 by 4–6 cm.; it occurs in
the Commentry Coal-field of France in association with the fronds known
A. Caulopteris peltigera.
B. Megaphyton insigne.
(After Grand’Eury.) Much reduced.
Psaronius stems preserved as casts showing surface-features, or in a
decorticated state.
i. Caulopteris.
This generic name was instituted by Lindley and Hutton[1079] for tree-fern
stems from the English Coal-Measures showing circular or oval scars
arranged quincuncially. The vascular tissue of the petiole is represented by a
U-shaped impression on the scar, the ends of the U being incurved, or by a
closed oval ring with a wide-open and inverted V near its upper end. The
surface between the leaf-scars bears the impression of adventitious roots.
Caulopteris is represented, in the Upper Coal-Measures of England, by C.
anglica[1080] Kidst. The species C. peltigera (fig. 298, A), originally
described by Brongniart as Sigillaria, illustrates the closed form of leaf-
trace and, as Zeiller suggests, it is the cast of a Psaronius stem which
possessed a vascular system on the same plan as that of P. infarctus. C.
Saportae[1081] illustrates the open U-shaped type of petiole stele.
Caulopteris peltigera has scars measuring 6–9 by 4–6 cm.; it occurs in
the Commentry Coal-field of France in association with the fronds known
Page 465
as Pecopteris cyathea, a species which Kidston regards as identical with P.
arborescens[1082].
ii. Megaphyton.
The first use of this name was by Artis[1083], who gave it to a long
flattened cast, Megaphyton frondosum, found in Carboniferous strata in
Yorkshire, characterised by two vertical rows of large scars and by
impressions of sinuous roots. Kidston records the genus from the Middle
and Upper Coal-Measures of Britain. A good example of this type of cast is
afforded by M. McLayi Lesq.[1084] from the Coal-Measures of North
America, which has been recognised in European Carboniferous rocks. The
leaf-scars are rounded or oval, broader than high; the vascular impression
has the form of a closed ring (5–8 × 3–6 cm.), more or less circular and
with a tendency to a rectangular outline, characterised by a deep inverted U-
shaped sinus in the middle of the lower surface and by a W-shaped
impression of an internal strand (fig. 298, B)[1085].
iii. Ptychopteris.
This generic name, instituted by Corda[1086], is applied to decorticated
stems of Psaronius, the surface of which is that of the vascular region on
which the form of the leaf-scars is more or less clearly defined. The scar-
areas are limited by an impression of the sclerenchymatous sheath
enclosing the leaf-meristele, and internal to this is the impression of the
leaf-trace. In some specimens a layer of coaly material which represents the
carbonised cortex and adventitious roots covers the Ptychopteris cast. The
Ptychopteris cast represented in fig. 299 shows the decorticated surface of
part of a long stem on which the leaf-scars are arranged as in Megaphyton.
An example of Ptychopteris is figured by Fontaine and White[1087] from
Virginia as Caulopteris gigantea.
arborescens[1082].
ii. Megaphyton.
The first use of this name was by Artis[1083], who gave it to a long
flattened cast, Megaphyton frondosum, found in Carboniferous strata in
Yorkshire, characterised by two vertical rows of large scars and by
impressions of sinuous roots. Kidston records the genus from the Middle
and Upper Coal-Measures of Britain. A good example of this type of cast is
afforded by M. McLayi Lesq.[1084] from the Coal-Measures of North
America, which has been recognised in European Carboniferous rocks. The
leaf-scars are rounded or oval, broader than high; the vascular impression
has the form of a closed ring (5–8 × 3–6 cm.), more or less circular and
with a tendency to a rectangular outline, characterised by a deep inverted U-
shaped sinus in the middle of the lower surface and by a W-shaped
impression of an internal strand (fig. 298, B)[1085].
iii. Ptychopteris.
This generic name, instituted by Corda[1086], is applied to decorticated
stems of Psaronius, the surface of which is that of the vascular region on
which the form of the leaf-scars is more or less clearly defined. The scar-
areas are limited by an impression of the sclerenchymatous sheath
enclosing the leaf-meristele, and internal to this is the impression of the
leaf-trace. In some specimens a layer of coaly material which represents the
carbonised cortex and adventitious roots covers the Ptychopteris cast. The
Ptychopteris cast represented in fig. 299 shows the decorticated surface of
part of a long stem on which the leaf-scars are arranged as in Megaphyton.
An example of Ptychopteris is figured by Fontaine and White[1087] from
Virginia as Caulopteris gigantea.
Page 466
Fig. 299. Ptychopteris. ⅙ nat. size. From the Middle Coal-Measures of Lancashire. (The
Manchester Museum.)
Manchester Museum.)
Page 467
Fig. 300. Dicksonia antarctica (half of stem in transverse section): st, stele; s, sclerenchyma.
Position of Psaronius.
A comparison of Psaronius with the Marattiaceae and other recent ferns
leads to the conclusion that, on the whole, the evidence is in favour of the
view usually held, namely that this genus is more closely related to the
Marattiaceae than to any other recent ferns. It is, however, important not to
overlook the differences between Psaronius and recent genera of
Marattiaceae, or the resemblances between the extinct genus and the
Cyatheaceae. In habit Psaronius agrees closely with recent tree-ferns; in the
vascular system and in the sequence of events connected with the
production of leaf-traces, there are striking resemblances between
Psaronius and the Cyatheaceous fern Saccoloma adiantoides (= Dicksonia
Plumieri Hook.) as described by Mettenius[1088]. The piece of stem of
Dicksonia antarctica represented in fig. 300 exhibits a fairly close
agreement with species of Psaronius, e.g. P. infarctus (fig. 296, A, B).
Moreover, the peripheral steles, which Zeiller has shown are confined to the
stem and play an important part in the production of the roots and in the
anastomoses with leaf-traces, are not represented in any Marattiaceous fern;
on the other hand, they are comparable with the accessory strands met with
in stems of recent Cyatheaceous tree-ferns[1089] (cf. fig. 240). The complex
system of concentric dictyosteles is a feature more closely matched in
Angiopteris (Marattiaceae) than in any Cyatheaceous genus, the chief
difference being in the more band-like form of the steles in Psaronius,
though in a stem of Angiopteris figured by Mettenius we see a close
Position of Psaronius.
A comparison of Psaronius with the Marattiaceae and other recent ferns
leads to the conclusion that, on the whole, the evidence is in favour of the
view usually held, namely that this genus is more closely related to the
Marattiaceae than to any other recent ferns. It is, however, important not to
overlook the differences between Psaronius and recent genera of
Marattiaceae, or the resemblances between the extinct genus and the
Cyatheaceae. In habit Psaronius agrees closely with recent tree-ferns; in the
vascular system and in the sequence of events connected with the
production of leaf-traces, there are striking resemblances between
Psaronius and the Cyatheaceous fern Saccoloma adiantoides (= Dicksonia
Plumieri Hook.) as described by Mettenius[1088]. The piece of stem of
Dicksonia antarctica represented in fig. 300 exhibits a fairly close
agreement with species of Psaronius, e.g. P. infarctus (fig. 296, A, B).
Moreover, the peripheral steles, which Zeiller has shown are confined to the
stem and play an important part in the production of the roots and in the
anastomoses with leaf-traces, are not represented in any Marattiaceous fern;
on the other hand, they are comparable with the accessory strands met with
in stems of recent Cyatheaceous tree-ferns[1089] (cf. fig. 240). The complex
system of concentric dictyosteles is a feature more closely matched in
Angiopteris (Marattiaceae) than in any Cyatheaceous genus, the chief
difference being in the more band-like form of the steles in Psaronius,
though in a stem of Angiopteris figured by Mettenius we see a close
Page 468
approach to the extinct type. The position of the protoxylem has
unfortunately not been clearly defined in Psaronius stems, but in P. Renaulti
it is stated by Scott[1090] to be endarch, a position which some of the
protoxylem strands occupy in Angiopteris[1091]. The occurrence of large
sieve-tubes described by Scott in P. Renaultii is another feature shared by
recent Marattiaceae. In many of the continental species of Psaronius the
phloem has not been preserved, and our knowledge of this tissue is
comparatively meagre. In the Marattiaceae the roots arise mainly from the
inner portions of the stele, while in Psaronius they are usually formed from
the external vascular bands. The formation of secondary cortical tissue is a
peculiarity of Psaronius; on the other hand, if Butterworth[1092] is correct in
referring to that genus the roots with secondary xylem, which he describes
as P. Cromptonensis, a comparison may be made with the occurrence of
secondary tracheae in the stem steles of Angiopteris[1093].
The absence of mechanical tissue in the stem of Angiopteris is in contrast
with its occurrence in the fossil stems and in recent tree-ferns; but this is a
character of secondary importance and one which can be readily explained
by the difference in habit between Angiopteris and Psaronius.
The roots of Psaronius, more especially as regards the stelar structure,
are in close agreement with those of Marattiaceae.
The reference to Marattiaceae of the great majority of fertile fern-like
fronds from Permian and Carboniferous rocks constituted a strong a priori
argument in favour of including Psaronius stems in the same family,
especially when it was known that leaves with Marattiaceous synangia were
borne by species of this genus. It is, however, well to remember the change
in our views as to the dominance of Marattiaceae in Palaeozoic floras
consequent on the discovery of the Pteridosperms. The association of fronds
bearing Asterotheca and Scolecopteris types of fructification with Psaronius
stems recorded by Grand’Eury[1094] is a point in favour of the Marattiaceous
affinity of this extinct genus, but it is not impossible that Psaronius stems
bore fronds which produced Pteridosperm organs of reproduction. In this
connexion the specimen represented in fig. 297 is of interest, as the fronds
(Pecopteris Sterzeli) borne on the Psaronius stems are hardly
distinguishable from the seed-bearing leaves known as Pecopteris
Pluckeneti.
unfortunately not been clearly defined in Psaronius stems, but in P. Renaulti
it is stated by Scott[1090] to be endarch, a position which some of the
protoxylem strands occupy in Angiopteris[1091]. The occurrence of large
sieve-tubes described by Scott in P. Renaultii is another feature shared by
recent Marattiaceae. In many of the continental species of Psaronius the
phloem has not been preserved, and our knowledge of this tissue is
comparatively meagre. In the Marattiaceae the roots arise mainly from the
inner portions of the stele, while in Psaronius they are usually formed from
the external vascular bands. The formation of secondary cortical tissue is a
peculiarity of Psaronius; on the other hand, if Butterworth[1092] is correct in
referring to that genus the roots with secondary xylem, which he describes
as P. Cromptonensis, a comparison may be made with the occurrence of
secondary tracheae in the stem steles of Angiopteris[1093].
The absence of mechanical tissue in the stem of Angiopteris is in contrast
with its occurrence in the fossil stems and in recent tree-ferns; but this is a
character of secondary importance and one which can be readily explained
by the difference in habit between Angiopteris and Psaronius.
The roots of Psaronius, more especially as regards the stelar structure,
are in close agreement with those of Marattiaceae.
The reference to Marattiaceae of the great majority of fertile fern-like
fronds from Permian and Carboniferous rocks constituted a strong a priori
argument in favour of including Psaronius stems in the same family,
especially when it was known that leaves with Marattiaceous synangia were
borne by species of this genus. It is, however, well to remember the change
in our views as to the dominance of Marattiaceae in Palaeozoic floras
consequent on the discovery of the Pteridosperms. The association of fronds
bearing Asterotheca and Scolecopteris types of fructification with Psaronius
stems recorded by Grand’Eury[1094] is a point in favour of the Marattiaceous
affinity of this extinct genus, but it is not impossible that Psaronius stems
bore fronds which produced Pteridosperm organs of reproduction. In this
connexion the specimen represented in fig. 297 is of interest, as the fronds
(Pecopteris Sterzeli) borne on the Psaronius stems are hardly
distinguishable from the seed-bearing leaves known as Pecopteris
Pluckeneti.
Page 469
The position of Psaronius may be best expressed by assigning it to a
separate family, the Psaronieae, as advocated by Stenzel, and by regarding it
as one of the many instances of a generalised type which in the sum of its
characters approaches most nearly to the Marattiaceae.
separate family, the Psaronieae, as advocated by Stenzel, and by regarding it
as one of the many instances of a generalised type which in the sum of its
characters approaches most nearly to the Marattiaceae.
Page 470
Page 471
CHAPTER XXIV.
Ophioglossales (Fossil).
The fossils hitherto classed with the Ophioglossales are not such as
afford any satisfactory evidence in regard to the past history or phylogeny
of the group. In the generalised class of Palaeozoic ferns, the
Botryopterideae, we find certain characters suggesting comparison with
recent members of the Ophioglossaceae, but no trustworthy records of these
eusporangiate ferns are furnished by the older plant-bearing strata.
Fig. 301. Rhacopteris sp., Ballycastle, Ireland. From a specimen in the Manchester
Museum. [M.S.]
The genus Rhacopteris (fig. 301), characteristic of the Culm flora, has
been compared with Botrychium, but on grounds which are wholly
inadequate. The species R. paniculifera Stur[1095] is characterised by a stout
rachis bearing two rows of laterally attached rhomboidal or subtriangular
segments with a more or less deeply lobed margin and spreading veins. The
rachis branches distally into two arms, and these are again symmetrically
Ophioglossales (Fossil).
The fossils hitherto classed with the Ophioglossales are not such as
afford any satisfactory evidence in regard to the past history or phylogeny
of the group. In the generalised class of Palaeozoic ferns, the
Botryopterideae, we find certain characters suggesting comparison with
recent members of the Ophioglossaceae, but no trustworthy records of these
eusporangiate ferns are furnished by the older plant-bearing strata.
Fig. 301. Rhacopteris sp., Ballycastle, Ireland. From a specimen in the Manchester
Museum. [M.S.]
The genus Rhacopteris (fig. 301), characteristic of the Culm flora, has
been compared with Botrychium, but on grounds which are wholly
inadequate. The species R. paniculifera Stur[1095] is characterised by a stout
rachis bearing two rows of laterally attached rhomboidal or subtriangular
segments with a more or less deeply lobed margin and spreading veins. The
rachis branches distally into two arms, and these are again symmetrically
Page 472
subdivided into fertile axes bearing clusters of small spherical bodies 1 mm.
broad, which Stur speaks of as exannulate sporangia similar to those of
Botrychium. He includes the species in the Ophioglossaceae. As Zeiller[1096]
pertinently remarks, Rhacopteris differs essentially in habit from any recent
member of this family. Rhacopteris also includes species characterised by
leaflets deeply dissected into linear segments; an example of this form is
represented by Rhacopteris flabellata (Tate) recorded by Kidston[1097] from
rocks of Calciferous Sandstone age in Flintshire.
The specimen described by Renault[1098] from the Carboniferous rocks of
Autun as Ophioglossites antiqua is equally unconvincing: it consists of a
carbonised fragment, 7 cm. × 1·5 cm., regarded as part of a fertile lamina
characterised by a vertical series of transversely elongated slits, 7 mm.
wide, some of which, on slight magnification, are seen to contain a mass of
small orange-yellow granulations. The slits are compared with the surface-
openings of the sunken sporangia of Ophioglossum, and the yellow bodies
are identified as spores. The material is too imperfect to justify the use of
the name Ophioglossites.
Noeggerathia.
This genus of uncertain position may be briefly described here, though it
has little claim to recognition as a representative of the Ophioglossales. It is
characteristic of Lower Carboniferous rocks and is compared by Stur[1099]
with recent Ophioglossaceae. Noeggerathia foliosa Sternb. (fig. 302) may
be cited as a typical example of the genus. It consists of an axis bearing
ovate leaves with numerous spreading veins. The upper part of the axis
forms a spike composed of fertile leaves in the form of transversely oval
bracts 2 cm. broad with a serrate edge bearing on the upper face several
sporangia (3 × 4 mm.) in some of which spores have been seen (fig. 302, B,
C). In another form described by Weiss[1100] the bracts bear a greater number
of sporangia characterised by the presence of an arillus-like basal ring.
broad, which Stur speaks of as exannulate sporangia similar to those of
Botrychium. He includes the species in the Ophioglossaceae. As Zeiller[1096]
pertinently remarks, Rhacopteris differs essentially in habit from any recent
member of this family. Rhacopteris also includes species characterised by
leaflets deeply dissected into linear segments; an example of this form is
represented by Rhacopteris flabellata (Tate) recorded by Kidston[1097] from
rocks of Calciferous Sandstone age in Flintshire.
The specimen described by Renault[1098] from the Carboniferous rocks of
Autun as Ophioglossites antiqua is equally unconvincing: it consists of a
carbonised fragment, 7 cm. × 1·5 cm., regarded as part of a fertile lamina
characterised by a vertical series of transversely elongated slits, 7 mm.
wide, some of which, on slight magnification, are seen to contain a mass of
small orange-yellow granulations. The slits are compared with the surface-
openings of the sunken sporangia of Ophioglossum, and the yellow bodies
are identified as spores. The material is too imperfect to justify the use of
the name Ophioglossites.
Noeggerathia.
This genus of uncertain position may be briefly described here, though it
has little claim to recognition as a representative of the Ophioglossales. It is
characteristic of Lower Carboniferous rocks and is compared by Stur[1099]
with recent Ophioglossaceae. Noeggerathia foliosa Sternb. (fig. 302) may
be cited as a typical example of the genus. It consists of an axis bearing
ovate leaves with numerous spreading veins. The upper part of the axis
forms a spike composed of fertile leaves in the form of transversely oval
bracts 2 cm. broad with a serrate edge bearing on the upper face several
sporangia (3 × 4 mm.) in some of which spores have been seen (fig. 302, B,
C). In another form described by Weiss[1100] the bracts bear a greater number
of sporangia characterised by the presence of an arillus-like basal ring.
Page 473
Fig. 302. Noeggerathia foliosa. (After Stur; A, reduced.) B, Fertile leaf; C, Sporangium.
Geinitz[1101], who first described fertile specimens of Noeggerathia,
placed the genus in the Gymnosperms, and O. Feistmantel[1102] was in
favour of this view. C. Feistmantel[1103], who described the small bodies in
the sporangia, suggested comparison with Schizaeaceae, and Weiss[1104]
discussed various possibilities, asking but not answering the question, are
the so-called sporangia rightly so named or are they fruits? Potonié[1105]
places the genus in the Cycadofilices. An important feature is the
occurrence of the sporangia on the upper face of the bracts as in
Lycopodiales and Sphenophyllum, but in other respects Noeggerathia bears
Geinitz[1101], who first described fertile specimens of Noeggerathia,
placed the genus in the Gymnosperms, and O. Feistmantel[1102] was in
favour of this view. C. Feistmantel[1103], who described the small bodies in
the sporangia, suggested comparison with Schizaeaceae, and Weiss[1104]
discussed various possibilities, asking but not answering the question, are
the so-called sporangia rightly so named or are they fruits? Potonié[1105]
places the genus in the Cycadofilices. An important feature is the
occurrence of the sporangia on the upper face of the bracts as in
Lycopodiales and Sphenophyllum, but in other respects Noeggerathia bears
Page 474
no resemblance to these two groups. Sterile examples of the genus are
similar in habit to Rhacopteris, but in the latter genus the leaves or leaflets
are laterally attached and not obliquely inserted. Further, we may assume
that in Rhacopteris the segments are leaflets of a compound leaf, whereas in
Noeggerathia they are probably single leaves. We must leave the position of
this Lower Carboniferous genus undecided, merely expressing the opinion
that it is perhaps more nearly allied to the Cycads than to any other group.
Fig. 303. Chiropteris Zeilleri, Sew. [From a specimen in the British Museum (v. 3268). Nat.
size.]
The plant figured by Lindley and Hutton from the English Coal-
Measures as Noeggerathia flabellata, which some authors quote as a
species of Noeggerathia, is generally recognised as a Psygmophyllum and
placed with some hesitation in the Ginkgoales.
Chiropteris.
This genus was founded by Kurr on a leaf characterised by anastomosing
venation from Keuper beds near Stuttgart. A resemblance in form and
similar in habit to Rhacopteris, but in the latter genus the leaves or leaflets
are laterally attached and not obliquely inserted. Further, we may assume
that in Rhacopteris the segments are leaflets of a compound leaf, whereas in
Noeggerathia they are probably single leaves. We must leave the position of
this Lower Carboniferous genus undecided, merely expressing the opinion
that it is perhaps more nearly allied to the Cycads than to any other group.
Fig. 303. Chiropteris Zeilleri, Sew. [From a specimen in the British Museum (v. 3268). Nat.
size.]
The plant figured by Lindley and Hutton from the English Coal-
Measures as Noeggerathia flabellata, which some authors quote as a
species of Noeggerathia, is generally recognised as a Psygmophyllum and
placed with some hesitation in the Ginkgoales.
Chiropteris.
This genus was founded by Kurr on a leaf characterised by anastomosing
venation from Keuper beds near Stuttgart. A resemblance in form and
Page 475
venation to the leaves of recent species of Ophioglossum led authors to
suggest the inclusion of Kurr’s specimen in the Ophioglossaceae. We have,
however, no justification for considering Chiropteris as a member of this
family; it may be a fern, and that is all that can be said. The leaf represented
in fig. 303 is the type-specimen of a South African Rhaetic species
Chiropteris Zeilleri[1106]. The genus is recorded also from Rhaetic rocks in
Queensland.[1107]
Newberry[1108] describes some leaves from the Lower Cretaceous of
Montana as species of Chiropteris: one of his types, C. spatulata, is almost
certainly a Sagenopteris, similar to S. Phillipsi (figs. 327, 328) or S.
Mantelli. A second species, C. Williamsii, is probably not generically
identical with the specimen represented in fig. 303.
suggest the inclusion of Kurr’s specimen in the Ophioglossaceae. We have,
however, no justification for considering Chiropteris as a member of this
family; it may be a fern, and that is all that can be said. The leaf represented
in fig. 303 is the type-specimen of a South African Rhaetic species
Chiropteris Zeilleri[1106]. The genus is recorded also from Rhaetic rocks in
Queensland.[1107]
Newberry[1108] describes some leaves from the Lower Cretaceous of
Montana as species of Chiropteris: one of his types, C. spatulata, is almost
certainly a Sagenopteris, similar to S. Phillipsi (figs. 327, 328) or S.
Mantelli. A second species, C. Williamsii, is probably not generically
identical with the specimen represented in fig. 303.
Page 476
Page 477
CHAPTER XXV.
I. Botryoptereae.
Coenopterideae.
II. Zygoptereae.
The term Botryopterideae, first used by Renault, has been applied to a
group of Palaeozoic ferns ranging from the Lower Carboniferous to the
Permian and containing several genera, the distinguishing features of which
are supplied by the anatomical structure of the stems or, in many cases, by
that of the petiolar vascular strand. Scott[1109] subdivides the Botryopterideae
into the Botryopteris and the Zygopteris sections. In an admirable
monograph recently published by Paul Bertrand[1110] considerable changes
are proposed in current nomenclature; he substitutes the name
Inversicatenales for Botryopterideae, a designation, which as Scott remarks,
is “probably too technical to command general acceptance.” A more serious
criticism is that the name Inversicatenales has reference to a character (the
inverse curvature of the leaf-trace in relation to the axis of the stem) which
is by no means universal in the group[1111].
In the following account, necessarily incomplete, the generic terminology
of Bertrand is adopted, but this decision does not carry with it any
obligation to accept the name Inversicatenales. We may speak of the types
of Palaeozoic ferns dealt with in the following pages as members of a group
differing in many respects from any existing genera of the Filicales, and
exhibiting the characteristics associated with generalised plants.
Williamson, as early as 1883, spoke of Renault’s Botryopterideae as
comprising “altogether extinct and generalised” types[1112]. For these
generalised Palaeozoic ferns I propose to use the name Coenopterideae[1113].
This term may be adopted in a wider sense than Renault’s name
Botryopterideae. The name Primofilices proposed by Arber[1114] might be
employed, but the implication which it carries is an argument against its
adoption. We have not yet reached a stage in the investigation of extinct
types at which we are able to recognise what are actually primary or
primitive ferns. The search for origins will continue; as new discoveries are
I. Botryoptereae.
Coenopterideae.
II. Zygoptereae.
The term Botryopterideae, first used by Renault, has been applied to a
group of Palaeozoic ferns ranging from the Lower Carboniferous to the
Permian and containing several genera, the distinguishing features of which
are supplied by the anatomical structure of the stems or, in many cases, by
that of the petiolar vascular strand. Scott[1109] subdivides the Botryopterideae
into the Botryopteris and the Zygopteris sections. In an admirable
monograph recently published by Paul Bertrand[1110] considerable changes
are proposed in current nomenclature; he substitutes the name
Inversicatenales for Botryopterideae, a designation, which as Scott remarks,
is “probably too technical to command general acceptance.” A more serious
criticism is that the name Inversicatenales has reference to a character (the
inverse curvature of the leaf-trace in relation to the axis of the stem) which
is by no means universal in the group[1111].
In the following account, necessarily incomplete, the generic terminology
of Bertrand is adopted, but this decision does not carry with it any
obligation to accept the name Inversicatenales. We may speak of the types
of Palaeozoic ferns dealt with in the following pages as members of a group
differing in many respects from any existing genera of the Filicales, and
exhibiting the characteristics associated with generalised plants.
Williamson, as early as 1883, spoke of Renault’s Botryopterideae as
comprising “altogether extinct and generalised” types[1112]. For these
generalised Palaeozoic ferns I propose to use the name Coenopterideae[1113].
This term may be adopted in a wider sense than Renault’s name
Botryopterideae. The name Primofilices proposed by Arber[1114] might be
employed, but the implication which it carries is an argument against its
adoption. We have not yet reached a stage in the investigation of extinct
types at which we are able to recognise what are actually primary or
primitive ferns. The search for origins will continue; as new discoveries are
Page 478
made our point of view shifts and the primitive type of to-day may to-
morrow have to take a higher place. The epithet primitive or primary is in
reality provisional: to adopt such a name as Primofilices suggests a finality
which has not been, or is likely to be, achieved. The true ancestral type—
the Urform—which we strive to discover eludes the pursuer like a will-o’-
the-wisp.
Seeing that the number of true ferns of Palaeozoic age has been recently
considerably reduced and is likely to suffer further reduction, the
consideration of such undoubted Carboniferous and Permian examples of
the Filicales as are left acquires a special importance. In the first place it is
natural to ask whether the Palaeozoic ferns include any types which, if not
themselves ancestral forms, may serve to indicate the probable lines of
evolution of existing families. It is probable that in the near future our
knowledge of the Coenopterideae will be considerably extended; as yet we
possess meagre information in regard to those characters on which most
stress has generally been laid in the classification of recent ferns, namely
the structure of the spore-bearing organs. The sporangia of Diplolabis and
Stauropteris (figs. 309, A; 322) are exannulate; in the former genus they
occur in sori or synangia consisting of a small number of sporangia, while
in the latter they are borne singly at the tips of ultimate ramifications of a
highly compound leaf. The resemblance of the synangium of Diplolabis to
that of Kaulfussia (fig. 245, C) is not shared in an equal degree by the
sporangia of Stauropteris, which are in some respects comparable with
those of the Ophioglossaceae. In the Zygoptereae, or at least in the case of
such fertile fronds as are known, and in Botryopteris (fig. 319), the
sporangia occur in groups, and the pedicel of each sporangium is supplied
with vascular tissue as in Helminthostachys. Another characteristic of the
sporangia of the extinct types is the possession of an annulus several cells in
breadth, a peculiarity which supplies a point of contact with the
Osmundaceae. In the sporangia of Kidstonia we have a similar though not
an identical type (fig. 256, E, p. 340). So far, then, as the evidence afforded
by sporangial characters is concerned, it points to comparison with the
Ophioglossaceae, the Osmundaceae, and the Marattiaceae. When we
compare the steles of the stems we find a wide range of structure. All the
genera agree in being monostelic; in Tubicaulis and Grammatopteris the
protoxylem is exarch, in Botryopteris it is internal, while the foliar strand of
Stauropteris and the stele of Ankyropteris corrugata are mesarch. The
morrow have to take a higher place. The epithet primitive or primary is in
reality provisional: to adopt such a name as Primofilices suggests a finality
which has not been, or is likely to be, achieved. The true ancestral type—
the Urform—which we strive to discover eludes the pursuer like a will-o’-
the-wisp.
Seeing that the number of true ferns of Palaeozoic age has been recently
considerably reduced and is likely to suffer further reduction, the
consideration of such undoubted Carboniferous and Permian examples of
the Filicales as are left acquires a special importance. In the first place it is
natural to ask whether the Palaeozoic ferns include any types which, if not
themselves ancestral forms, may serve to indicate the probable lines of
evolution of existing families. It is probable that in the near future our
knowledge of the Coenopterideae will be considerably extended; as yet we
possess meagre information in regard to those characters on which most
stress has generally been laid in the classification of recent ferns, namely
the structure of the spore-bearing organs. The sporangia of Diplolabis and
Stauropteris (figs. 309, A; 322) are exannulate; in the former genus they
occur in sori or synangia consisting of a small number of sporangia, while
in the latter they are borne singly at the tips of ultimate ramifications of a
highly compound leaf. The resemblance of the synangium of Diplolabis to
that of Kaulfussia (fig. 245, C) is not shared in an equal degree by the
sporangia of Stauropteris, which are in some respects comparable with
those of the Ophioglossaceae. In the Zygoptereae, or at least in the case of
such fertile fronds as are known, and in Botryopteris (fig. 319), the
sporangia occur in groups, and the pedicel of each sporangium is supplied
with vascular tissue as in Helminthostachys. Another characteristic of the
sporangia of the extinct types is the possession of an annulus several cells in
breadth, a peculiarity which supplies a point of contact with the
Osmundaceae. In the sporangia of Kidstonia we have a similar though not
an identical type (fig. 256, E, p. 340). So far, then, as the evidence afforded
by sporangial characters is concerned, it points to comparison with the
Ophioglossaceae, the Osmundaceae, and the Marattiaceae. When we
compare the steles of the stems we find a wide range of structure. All the
genera agree in being monostelic; in Tubicaulis and Grammatopteris the
protoxylem is exarch, in Botryopteris it is internal, while the foliar strand of
Stauropteris and the stele of Ankyropteris corrugata are mesarch. The
Page 479
axillary branching of species of Ankyropteris suggests comparison with the
Hymenophyllaceae.
The investigation of the vascular system of the petioles has afforded
results which in the hands of P. Bertrand have led to conclusions in regard
to inter-relationships. We must, however, not overlook the danger of
attributing can excessive importance to this single criterion and of
neglecting the facts of stem anatomy.
I. Botryoptereae.
Grammatopteris.
Renault instituted this genus for petrified stems from the Permo-
Carboniferous beds of Autun. Grammatopteris Rigolloti[1115], the type-
species, is represented by a fragment, 12–15 mm. in diameter, surrounded
by crowded petioles characterised by a vascular strand in the form of a short
and comparatively broad plate with the smallest tracheae at each end. The
solid xylem of the stem stele (protostele) has peripheral groups of
protoxylem. Nothing is known as to the form of the leaves, but sporangia
similar to those of Etapteris (Zygopteris) were found in association with the
stem. It is possible, as P. Bertrand suggests, that Renault’s species may be
the stem of a Tubicaulis.
Tubicaulis.
Tubicaulis solenites (Sprengel)[1116]. Fig. 304.
This species from the Lower Permian of Saxony has been fully described
by Stenzel[1117]. It is characterised by a very slender erect stem bearing
numerous spirally disposed leaves associated with adventitious roots; the
single stele (protostele) consists exclusively of tracheae, described as
intermediate between the scalariform and reticulate type, surrounded by
phloem. Leaf-traces are given off from the periphery of the stele where
groups of smaller elements occur; these have the form of a wide-open U-
shaped strand with the base of the U facing the axis of the stem. As the trace
passes out towards the leaves, the ends of the U become more or less
incurved. The stem is said to reach a metre in length and to bear compound
Hymenophyllaceae.
The investigation of the vascular system of the petioles has afforded
results which in the hands of P. Bertrand have led to conclusions in regard
to inter-relationships. We must, however, not overlook the danger of
attributing can excessive importance to this single criterion and of
neglecting the facts of stem anatomy.
I. Botryoptereae.
Grammatopteris.
Renault instituted this genus for petrified stems from the Permo-
Carboniferous beds of Autun. Grammatopteris Rigolloti[1115], the type-
species, is represented by a fragment, 12–15 mm. in diameter, surrounded
by crowded petioles characterised by a vascular strand in the form of a short
and comparatively broad plate with the smallest tracheae at each end. The
solid xylem of the stem stele (protostele) has peripheral groups of
protoxylem. Nothing is known as to the form of the leaves, but sporangia
similar to those of Etapteris (Zygopteris) were found in association with the
stem. It is possible, as P. Bertrand suggests, that Renault’s species may be
the stem of a Tubicaulis.
Tubicaulis.
Tubicaulis solenites (Sprengel)[1116]. Fig. 304.
This species from the Lower Permian of Saxony has been fully described
by Stenzel[1117]. It is characterised by a very slender erect stem bearing
numerous spirally disposed leaves associated with adventitious roots; the
single stele (protostele) consists exclusively of tracheae, described as
intermediate between the scalariform and reticulate type, surrounded by
phloem. Leaf-traces are given off from the periphery of the stele where
groups of smaller elements occur; these have the form of a wide-open U-
shaped strand with the base of the U facing the axis of the stem. As the trace
passes out towards the leaves, the ends of the U become more or less
incurved. The stem is said to reach a metre in length and to bear compound
Page 480
fronds a metre long. The orientation of the leaf-trace with its concavity
turned outwards is in striking contrast to the relation between leaf-trace and
stem in recent ferns.
Fig. 304. Tubicaulis solenites. (From Tansley, after Stenzel.) Stem and petioles: the latter
numbered in the order of their age.
Tubicaulis Sutcliffii, Stopes[1118].
In this species the vascular axis, 2 mm. in diameter, is almost cylindrical
and of the protostelic type with the protoxylem “near to or at the edge”: the
tracheae are scalariform or reticulate. The leaf-traces, when first separated
from the edge of the stele, are oval and gradually assume the curved form
seen in T. solenites (fig. 304) with the convex side towards the axis of the
stem. The transition from the scalariform to the reticulate type of pitting on
the tracheal walls referred to by Miss Stopes has also been noticed in some
recent ferns (e.g. Helminthostachys) and in Sigillaria (fig. 200, C, p. 212).
The fact that the scalariform type of pitting is practically universal in the
xylem of recent ferns, would seem to show that this character has been
acquired in the course of evolution and retained in preference to the
reticulate form characteristic of several Palaeozoic species. The distinction
between the two methods of pitting is one of little phylogenetic importance.
Botryopteris.
turned outwards is in striking contrast to the relation between leaf-trace and
stem in recent ferns.
Fig. 304. Tubicaulis solenites. (From Tansley, after Stenzel.) Stem and petioles: the latter
numbered in the order of their age.
Tubicaulis Sutcliffii, Stopes[1118].
In this species the vascular axis, 2 mm. in diameter, is almost cylindrical
and of the protostelic type with the protoxylem “near to or at the edge”: the
tracheae are scalariform or reticulate. The leaf-traces, when first separated
from the edge of the stele, are oval and gradually assume the curved form
seen in T. solenites (fig. 304) with the convex side towards the axis of the
stem. The transition from the scalariform to the reticulate type of pitting on
the tracheal walls referred to by Miss Stopes has also been noticed in some
recent ferns (e.g. Helminthostachys) and in Sigillaria (fig. 200, C, p. 212).
The fact that the scalariform type of pitting is practically universal in the
xylem of recent ferns, would seem to show that this character has been
acquired in the course of evolution and retained in preference to the
reticulate form characteristic of several Palaeozoic species. The distinction
between the two methods of pitting is one of little phylogenetic importance.
Botryopteris.
Page 481
This genus, founded by Renault on a specimen from Autun, is
represented in the Lower Coal-Measures of England by Botryopteris hirsuta
(= Rachiopteris hirsuta Will.), B. ramosa (= R. ramosa Will.[1119]) (fig. 306)
and B. cylindrica (fig. 305), also by B. antiqua (fig. 307) from the Culm of
Pettycur, Scotland.
An important characteristic of the genus is the solid stele of the stem
which agrees with that of Tubicaulis and Grammatopteris, except in the
central or peripheral position of the smallest tracheae.
Botryopteris forensis Renault[1120]. Figs. 309, B; 319, D–G.
The stem of this species from the Upper Carboniferous of St Étienne is
1·7 cm. x 7·5 mm. in diameter. The solid stele consists of reticulate tracheae
with the smallest elements on the outer edge. The comparatively broad
cortex of the type-specimen is traversed by a leaf-trace in an almost vertical
course and by vascular strands passing horizontally to roots. The petioles
are circular in section and their vascular strand has the form of an ω in
transverse section (fig. 319, G), the three projecting arms pointing to the
axis of the stem. Both stem and leaves bore large multicellular hairs, spoken
of by Renault as equisetiform because of the finely toothed sheaths of
which they are composed. The compound fronds had fleshy lobed pinnules
with dichotomously branched veins (fig. 309, B); stomata are said to be
confined to the upper surface, an observation which leads Renault to
describe the plant as aquatic on evidence which is hardly convincing.
The pyriform and pedicellate sporangia are borne in groups of two to six
on the ultimate divisions of the frond; the wall is composed of two layers of
cells and on one side of the sporangium is an annulus several cells in
breadth (fig. 319, D, F). An interesting type of sporangium described by
Oliver[1121] from Grand’Croix in France may, as he suggests, belong to
Botryopteris forensis; the differences between Renault’s and Oliver’s
specimens being the result of the more perfect preservation of the tissues in
the latter. The sporangium described by the English author is circular in
section and measures 0·65 × 0·53 mm.; the wall is in part composed of a
single layer of cells and in part of two to three layers, a character recalling
the “annulate” sporangia of Botryopteris. Between the spore-mass and the
wall is an interrupted ring of short tracheal elements similar to the xylem-
mantle which occurs at the periphery of the nucellus of certain Palaeozoic
represented in the Lower Coal-Measures of England by Botryopteris hirsuta
(= Rachiopteris hirsuta Will.), B. ramosa (= R. ramosa Will.[1119]) (fig. 306)
and B. cylindrica (fig. 305), also by B. antiqua (fig. 307) from the Culm of
Pettycur, Scotland.
An important characteristic of the genus is the solid stele of the stem
which agrees with that of Tubicaulis and Grammatopteris, except in the
central or peripheral position of the smallest tracheae.
Botryopteris forensis Renault[1120]. Figs. 309, B; 319, D–G.
The stem of this species from the Upper Carboniferous of St Étienne is
1·7 cm. x 7·5 mm. in diameter. The solid stele consists of reticulate tracheae
with the smallest elements on the outer edge. The comparatively broad
cortex of the type-specimen is traversed by a leaf-trace in an almost vertical
course and by vascular strands passing horizontally to roots. The petioles
are circular in section and their vascular strand has the form of an ω in
transverse section (fig. 319, G), the three projecting arms pointing to the
axis of the stem. Both stem and leaves bore large multicellular hairs, spoken
of by Renault as equisetiform because of the finely toothed sheaths of
which they are composed. The compound fronds had fleshy lobed pinnules
with dichotomously branched veins (fig. 309, B); stomata are said to be
confined to the upper surface, an observation which leads Renault to
describe the plant as aquatic on evidence which is hardly convincing.
The pyriform and pedicellate sporangia are borne in groups of two to six
on the ultimate divisions of the frond; the wall is composed of two layers of
cells and on one side of the sporangium is an annulus several cells in
breadth (fig. 319, D, F). An interesting type of sporangium described by
Oliver[1121] from Grand’Croix in France may, as he suggests, belong to
Botryopteris forensis; the differences between Renault’s and Oliver’s
specimens being the result of the more perfect preservation of the tissues in
the latter. The sporangium described by the English author is circular in
section and measures 0·65 × 0·53 mm.; the wall is in part composed of a
single layer of cells and in part of two to three layers, a character recalling
the “annulate” sporangia of Botryopteris. Between the spore-mass and the
wall is an interrupted ring of short tracheal elements similar to the xylem-
mantle which occurs at the periphery of the nucellus of certain Palaeozoic
Page 482
gymnospermous seeds. In the absence of proof of a connexion between this
sporangium and Botryopteris it is convenient to use the generic name
Tracheotheca subsequently proposed by Oliver[1122]. In the recent ferns
Helminthostachys and Botrychium, and, as Oliver notices, in the
microsporangia of the Australian Cycad Bowenia spectabilis, vascular
strands extend almost to the sporogenous tissue, but the fossil sporangium
is unique in having a tracheal layer in immediate contact with the spores.
These xylem elements may, as Oliver suggests, have served the purpose of
conveying water to the ripening spores.
Botryopteris hirsuta (Will.)[1123].
This English species has a slender axis bearing numerous leaves with
petioles equal in diameter to the stem. The surface of the vegetative organs
bears large multicellular hairs. The leaf-traces resemble those of B. forensis,
but the projecting teeth which terminate in protoxylem elements are less
prominent than in the French species; the petioles were named by Felix
Rachiopteris tridentata[1124]. As a leaf-trace passes into the stele of the stem
the three protoxylem strands unite and take up an internal position in the
solid stele. The stele may, therefore, be described as endarch. The small
tracheae at the edge of the stele supply the xylem strands of adventitious
roots.
Sporangia similar to those of B. forensis have been found in association
with the English species.
Botryopteris cylindrica (Will.). Fig. 305.
A plant originally described by Williamson[1125] from the Lower Coal-
Measures of England as Rachiopteris cylindrica (fig. 305) and afterwards
more fully dealt with by Hick[1126], has a slender stem with a cylindrical stele
characterised by well-defined central protoxylem elements in one or two
groups. The leaf-traces are semi-lunar in section with the protoxylem on the
flatter side. The stele of Botryopteris cylindrica (fig. 305, A) is more
cylindrical in section than that of B. ramosa (fig. 306) and shows more
clearly the differentiation into smaller central and larger peripheral tracheae.
In the section reproduced in fig. 305, B the stele is giving off a branch
almost identical in structure with the main vascular axis. Scott[1127], in
referring to the inclusion of this type in the genus Botryopteris, expresses
sporangium and Botryopteris it is convenient to use the generic name
Tracheotheca subsequently proposed by Oliver[1122]. In the recent ferns
Helminthostachys and Botrychium, and, as Oliver notices, in the
microsporangia of the Australian Cycad Bowenia spectabilis, vascular
strands extend almost to the sporogenous tissue, but the fossil sporangium
is unique in having a tracheal layer in immediate contact with the spores.
These xylem elements may, as Oliver suggests, have served the purpose of
conveying water to the ripening spores.
Botryopteris hirsuta (Will.)[1123].
This English species has a slender axis bearing numerous leaves with
petioles equal in diameter to the stem. The surface of the vegetative organs
bears large multicellular hairs. The leaf-traces resemble those of B. forensis,
but the projecting teeth which terminate in protoxylem elements are less
prominent than in the French species; the petioles were named by Felix
Rachiopteris tridentata[1124]. As a leaf-trace passes into the stele of the stem
the three protoxylem strands unite and take up an internal position in the
solid stele. The stele may, therefore, be described as endarch. The small
tracheae at the edge of the stele supply the xylem strands of adventitious
roots.
Sporangia similar to those of B. forensis have been found in association
with the English species.
Botryopteris cylindrica (Will.). Fig. 305.
A plant originally described by Williamson[1125] from the Lower Coal-
Measures of England as Rachiopteris cylindrica (fig. 305) and afterwards
more fully dealt with by Hick[1126], has a slender stem with a cylindrical stele
characterised by well-defined central protoxylem elements in one or two
groups. The leaf-traces are semi-lunar in section with the protoxylem on the
flatter side. The stele of Botryopteris cylindrica (fig. 305, A) is more
cylindrical in section than that of B. ramosa (fig. 306) and shows more
clearly the differentiation into smaller central and larger peripheral tracheae.
In the section reproduced in fig. 305, B the stele is giving off a branch
almost identical in structure with the main vascular axis. Scott[1127], in
referring to the inclusion of this type in the genus Botryopteris, expresses
Page 483
the opinion that its habit must have been very different from that of other
species, and he suggests the institution of a new genus.
species, and he suggests the institution of a new genus.
Page 484
Fig. 305. Botryopteris cylindrica (× 30). From sections in the Cambridge Botany School.
Page 485
Botryopteris ramosa (Williamson). Fig. 306.
This species, which bears a close resemblance to Botryopteris hirsuta,
was originally described by Williamson from the Lower Coal-Measures of
England as Rachiopteris ramosa[1128], the specific name being chosen on
account of the numerous and crowded branches given off from the main
axis. The section shown in fig. 306, A, illustrates Williamson’s description
of the stem as being “always surrounded [when seen in transverse sections]
by a swarm of similar sections of the large and small branches, though of
varying shapes and sizes.” The stele is composed of a solid and more or less
cylindrical rod of xylem tracheae of the reticulate type surrounded by
phloem (figs. A and D): one or more internal groups of smaller protoxylem
elements occur in an approximately central position (fig. A, px). The stele is
in fact endarch like those of Selaginella spinosa and Trichomanes
reniforme, a feature which, as Tansley[1129] believes, probably entitles the
vascular axis to be considered a primitive form of protostele. In the
specimens represented in fig. 306 the phloem and inner cortical tissues were
almost completely destroyed before petrifaction. The thick-walled outer
cortex bears at its periphery numerous multicellular hairs. Some of the
xylem strands given off from the stele no doubt supplied adventitious roots,
but in most cases the outgoing branches are leaf-traces and the numerous
sections of axes of different sizes seen in fig. A point to a repeated
subdivision of the crowded fronds. The structure of a petiole is shown in
figs. C and D. As seen in fig. C, the oval vascular strand has three
protoxylem groups, px, on its flatter side; a well-defined epidermal layer is
shown at e in fig. C.
Fig. B shows at a a section of a leaf-axis in the act of branching and the
row of branchlets at b represents a further stage in subdivision. At sp in fig.
A the section has cut through a single sporangium characterised by a group
of larger (“annulus”) cells on one side of the wall.
This species, which bears a close resemblance to Botryopteris hirsuta,
was originally described by Williamson from the Lower Coal-Measures of
England as Rachiopteris ramosa[1128], the specific name being chosen on
account of the numerous and crowded branches given off from the main
axis. The section shown in fig. 306, A, illustrates Williamson’s description
of the stem as being “always surrounded [when seen in transverse sections]
by a swarm of similar sections of the large and small branches, though of
varying shapes and sizes.” The stele is composed of a solid and more or less
cylindrical rod of xylem tracheae of the reticulate type surrounded by
phloem (figs. A and D): one or more internal groups of smaller protoxylem
elements occur in an approximately central position (fig. A, px). The stele is
in fact endarch like those of Selaginella spinosa and Trichomanes
reniforme, a feature which, as Tansley[1129] believes, probably entitles the
vascular axis to be considered a primitive form of protostele. In the
specimens represented in fig. 306 the phloem and inner cortical tissues were
almost completely destroyed before petrifaction. The thick-walled outer
cortex bears at its periphery numerous multicellular hairs. Some of the
xylem strands given off from the stele no doubt supplied adventitious roots,
but in most cases the outgoing branches are leaf-traces and the numerous
sections of axes of different sizes seen in fig. A point to a repeated
subdivision of the crowded fronds. The structure of a petiole is shown in
figs. C and D. As seen in fig. C, the oval vascular strand has three
protoxylem groups, px, on its flatter side; a well-defined epidermal layer is
shown at e in fig. C.
Fig. B shows at a a section of a leaf-axis in the act of branching and the
row of branchlets at b represents a further stage in subdivision. At sp in fig.
A the section has cut through a single sporangium characterised by a group
of larger (“annulus”) cells on one side of the wall.
Page 486
Fig. 306.
A–D. Botryopteris ramosa; stem and frond axes. (A × 7; B × 15; C × 26; D × 13.
From sections in the Cambridge Botany School Collection.) px, protoxylem; sp,
sporangium; e, epidermis.
This slender fern with its numerous repeatedly branched leaves may
perhaps have lived epiphytically on more robust plants.
Botryopteris antiqua, Kidst. Fig. 307.
This species, recently described by Kidston[1130] from the Culm of
Pettycur near Burntisland, is represented by sections of a small stem with a
A–D. Botryopteris ramosa; stem and frond axes. (A × 7; B × 15; C × 26; D × 13.
From sections in the Cambridge Botany School Collection.) px, protoxylem; sp,
sporangium; e, epidermis.
This slender fern with its numerous repeatedly branched leaves may
perhaps have lived epiphytically on more robust plants.
Botryopteris antiqua, Kidst. Fig. 307.
This species, recently described by Kidston[1130] from the Culm of
Pettycur near Burntisland, is represented by sections of a small stem with a
Page 487
cylindrical stele 0·40 mm. in diameter composed entirely of scalariform
tracheae without any recognisable protoxylem. The petioles are larger than
the stem; the meristele (fig. 307) is oval with protoxylem elements on the
slightly more rounded adaxial face. As Kidston suggests, this stem may
belong to a scrambling plant which required support to bear its relatively
large leaves. An interesting feature is the absence of projecting teeth in the
leaf-trace, a character in marked contrast to the ω form assumed by the
petioles of Botryopteris forensis (fig. 319, G) and B. hirsuta. This leads
Kidston to suggest that the vascular strand of the petiole tends “to become
more simple ... as traced back in geological time.” The greater similarity in
this species between the stele of the stem and that of the petiole is probably
another mark of a more primitive type.
Fig. 307. Botryopteris antiqua: Petiolar vascular strand. (After Kidston: × 65.)
• • • • •
In these three types, Grammatopteris, Tubicaulis, and Botryopteris, we
have monostelic plants, for the most part of very small size, with leaf-traces
varying in shape from the oblong band-form in Grammatopteris, and the
tracheae without any recognisable protoxylem. The petioles are larger than
the stem; the meristele (fig. 307) is oval with protoxylem elements on the
slightly more rounded adaxial face. As Kidston suggests, this stem may
belong to a scrambling plant which required support to bear its relatively
large leaves. An interesting feature is the absence of projecting teeth in the
leaf-trace, a character in marked contrast to the ω form assumed by the
petioles of Botryopteris forensis (fig. 319, G) and B. hirsuta. This leads
Kidston to suggest that the vascular strand of the petiole tends “to become
more simple ... as traced back in geological time.” The greater similarity in
this species between the stele of the stem and that of the petiole is probably
another mark of a more primitive type.
Fig. 307. Botryopteris antiqua: Petiolar vascular strand. (After Kidston: × 65.)
• • • • •
In these three types, Grammatopteris, Tubicaulis, and Botryopteris, we
have monostelic plants, for the most part of very small size, with leaf-traces
varying in shape from the oblong band-form in Grammatopteris, and the
Page 488
oval form of Botryopteris antiqua, to the ω type represented in its most
pronounced form by B. forensis. In several species the stem stele is endarch.
Our knowledge of the leaves is very meagre: in B. forensis they were
repeatedly branched and apparently bore small fleshy pinnules; the
sporangia, though differing from those of recent ferns, may be compared
with the spore-capsules of Osmundaceae as regards the structure of the
annulus. The abundance of hairs on the stems and leaves of some species,
the tracheal sheath in the sporangium described by Oliver[1131] as
Tracheotheca (= Botryopteris?), and the apparent absence of a large well-
developed lamina, may perhaps be regarded as evidence of xerophilous
conditions.
II. Zygoptereae.
Corda[1132] proposed the generic name Zygopteris for petrified petioles
from the Permian of Saxony, included by Cotta in his genus Tubicaulis,
which he named T. primarius. Corda’s genus has been generally used for
petioles of Palaeozoic ferns characterised by a vascular strand having the
form of an H in transverse section (fig. 308, D). Since the generic name was
instituted, information has been obtained in regard to the nature of the stems
which bore some of the petioles of the Zygopteris type; and for other
species of Zygopteris, the stems of which are still unknown, new generic
names have been proposed. P. Bertrand[1133] retains Zygopteris for one
species only, Z. primaria. Fig. 308, D, shows the character of the petiolar
vascular strand; the chief points are the comparatively long cross-pieces
(antennae of P. Bertrand) inclined at an angle of 45° to the plane of
symmetry of the petiole axis, and the groups of protoxylem elements shown
by the white patches in fig. D. In this as in other members of the
Zygoptereae the main rachis of the leaf gives off four sets of branches in
pairs alternately from the right and left side of the primary vascular axis.
This method of branching of the stele in the primary rachis of several
members of the Coenopterideae shows that the fronds bore pinnae laterally
disposed, in some cases in one row and in others in two rows on each side
of the rachis. In a typical fern frond, as represented by recent and most
fossil species, branching of the rachis occurs in the plane of the frond, that
is in the plane represented by the horizontal arm of xylem in Zygopteris
primaria connecting the two antennae or cross-pieces. In the Zygoptereae
pronounced form by B. forensis. In several species the stem stele is endarch.
Our knowledge of the leaves is very meagre: in B. forensis they were
repeatedly branched and apparently bore small fleshy pinnules; the
sporangia, though differing from those of recent ferns, may be compared
with the spore-capsules of Osmundaceae as regards the structure of the
annulus. The abundance of hairs on the stems and leaves of some species,
the tracheal sheath in the sporangium described by Oliver[1131] as
Tracheotheca (= Botryopteris?), and the apparent absence of a large well-
developed lamina, may perhaps be regarded as evidence of xerophilous
conditions.
II. Zygoptereae.
Corda[1132] proposed the generic name Zygopteris for petrified petioles
from the Permian of Saxony, included by Cotta in his genus Tubicaulis,
which he named T. primarius. Corda’s genus has been generally used for
petioles of Palaeozoic ferns characterised by a vascular strand having the
form of an H in transverse section (fig. 308, D). Since the generic name was
instituted, information has been obtained in regard to the nature of the stems
which bore some of the petioles of the Zygopteris type; and for other
species of Zygopteris, the stems of which are still unknown, new generic
names have been proposed. P. Bertrand[1133] retains Zygopteris for one
species only, Z. primaria. Fig. 308, D, shows the character of the petiolar
vascular strand; the chief points are the comparatively long cross-pieces
(antennae of P. Bertrand) inclined at an angle of 45° to the plane of
symmetry of the petiole axis, and the groups of protoxylem elements shown
by the white patches in fig. D. In this as in other members of the
Zygoptereae the main rachis of the leaf gives off four sets of branches in
pairs alternately from the right and left side of the primary vascular axis.
This method of branching of the stele in the primary rachis of several
members of the Coenopterideae shows that the fronds bore pinnae laterally
disposed, in some cases in one row and in others in two rows on each side
of the rachis. In a typical fern frond, as represented by recent and most
fossil species, branching of the rachis occurs in the plane of the frond, that
is in the plane represented by the horizontal arm of xylem in Zygopteris
primaria connecting the two antennae or cross-pieces. In the Zygoptereae
Page 489
the branches from the petiole vascular axis lie in a plane at right angles to
that of the frond; they lie in the transverse and not in the horizontal plane.
The two strands shown in fig. 308, B, 4, have been formed by the division
of a single strand, 3, in the transverse plane (i.e. in the plane of the paper).
As Tansley[1134] points out, a type of branching superficially similar to,
though not identical with this, is seen in some recent species of Gleichenia
and Lygodium. In this connexion it is worthy of note that a fern figured by
Unger from Thuringia as Sphenopteris petiolata Goepp[1135] bears pinnae in
two rows on the rachis which are characterised by repeated branching and
by a very narrow lamina or by slender naked axes; the occurrence of this
form of frond in rocks containing Clepsydropsis antiqua (fig. 308, A)
suggests a possible connexion between the petrified rachis and the
impressions of the leaves.
that of the frond; they lie in the transverse and not in the horizontal plane.
The two strands shown in fig. 308, B, 4, have been formed by the division
of a single strand, 3, in the transverse plane (i.e. in the plane of the paper).
As Tansley[1134] points out, a type of branching superficially similar to,
though not identical with this, is seen in some recent species of Gleichenia
and Lygodium. In this connexion it is worthy of note that a fern figured by
Unger from Thuringia as Sphenopteris petiolata Goepp[1135] bears pinnae in
two rows on the rachis which are characterised by repeated branching and
by a very narrow lamina or by slender naked axes; the occurrence of this
form of frond in rocks containing Clepsydropsis antiqua (fig. 308, A)
suggests a possible connexion between the petrified rachis and the
impressions of the leaves.
Page 490
Fig. 308.
A. Clepsydropsis antiqua.
B. Etapteris Scotti.
C. Diplolabis forensis.
D. Zygopteris primaria.
E–G. Stauropteris oldhamia.
The white patches in the xylem in figs. B–G mark the position of protoxylem elements.
(A, after Unger; B–G, after P. Bertrand.)
A. Clepsydropsis antiqua.
B. Etapteris Scotti.
C. Diplolabis forensis.
D. Zygopteris primaria.
E–G. Stauropteris oldhamia.
The white patches in the xylem in figs. B–G mark the position of protoxylem elements.
(A, after Unger; B–G, after P. Bertrand.)
Page 491
Fig. 309.
A. Diplolabis forensis.
B. Botryopteris forensis.
C, D. Corynepteris coralloides.
E. Schizopteris (Etapteris) pinnata.
(A, B, after Renault; C, D, after Zeiller; E, after Renault and Zeiller.)
The vascular strand of the rachis of Zygopteris primaria (fig. 308, D) is
simpler than that of most of the Zygoptereae and exhibits a close
A. Diplolabis forensis.
B. Botryopteris forensis.
C, D. Corynepteris coralloides.
E. Schizopteris (Etapteris) pinnata.
(A, B, after Renault; C, D, after Zeiller; E, after Renault and Zeiller.)
The vascular strand of the rachis of Zygopteris primaria (fig. 308, D) is
simpler than that of most of the Zygoptereae and exhibits a close
Page 492
resemblance to the type of strand described by Renault as Diplolabis (fig.
308, C).
Diplolabis.
Renault[1136] instituted this genus for two species from the Culm beds and
Coal-Measures of France based on the structure of the petioles. The stems
are unknown. The main rachis has a stele similar to that of Zygopteris
primaria, but distinguished by its greater similarity, in transverse section, to
an X rather than to the letter H: the long transverse bar in Zygopteris is here
much reduced in size. The petiole of Diplolabis forensis[1137] Ren. (fig. 308,
C) has a diameter of 1·5–2 cm. From the antennae a pair of small bundles is
given off alternately from the right and left side, as in Zygopteris; the
members of each pair coalesce after leaving the antennae and then separate
to pass into the lateral branches of the frond. The position of the protoxylem
and the formation of the lateral xylem strands previous to their separation
are shown in fig. 308, C. On the side of the vascular strand shown in fig. C,
2, the two lateral extensions of the antennae are converging towards one
another previous to their separation and subsequent union. The ovoid
sporangia occur in groups of three to six and are coalescent below with a
central receptacle; they have no annulus, but the cells on the side next the
receptacle are smaller than those on the external wall (fig. 309, A). The
synangial form of the sorus suggests comparison with Marattiaceae.
The species described by Renault from the Culm of Esnost is regarded by
P. Bertrand as identical with that described by Solms, from the Culm of
Falkenberg, as Zygopteris Roemeri[1138]. Diplolabis is compared by P.
Bertrand with Metaclepsydropsis, the generic name given to the Lower
Carboniferous petiole described by Williamson as Rachiopteris duplex[1139].
Mr Gordon has recently described in a preliminary note a new type of
stem stele under the name Zygopteris pettycurensis from the Lower
Carboniferous plant bed of Pettycur[1140]: he regards the petioles attached to
the stem as identical with Zygopteris Roemeri Solms-Laubach[1141]. This
species, founded by Solms-Laubach on petioles only, is placed by
Bertrand[1142] in the genus Diplolabis and regarded as identical with D.
esnostensis Ren. The stele found by Mr Gordon may therefore be assigned
to the genus Diplolabis: it includes two regions composed exclusively of
tracheae and is cylindrical in transverse section. The inner xylem zone
308, C).
Diplolabis.
Renault[1136] instituted this genus for two species from the Culm beds and
Coal-Measures of France based on the structure of the petioles. The stems
are unknown. The main rachis has a stele similar to that of Zygopteris
primaria, but distinguished by its greater similarity, in transverse section, to
an X rather than to the letter H: the long transverse bar in Zygopteris is here
much reduced in size. The petiole of Diplolabis forensis[1137] Ren. (fig. 308,
C) has a diameter of 1·5–2 cm. From the antennae a pair of small bundles is
given off alternately from the right and left side, as in Zygopteris; the
members of each pair coalesce after leaving the antennae and then separate
to pass into the lateral branches of the frond. The position of the protoxylem
and the formation of the lateral xylem strands previous to their separation
are shown in fig. 308, C. On the side of the vascular strand shown in fig. C,
2, the two lateral extensions of the antennae are converging towards one
another previous to their separation and subsequent union. The ovoid
sporangia occur in groups of three to six and are coalescent below with a
central receptacle; they have no annulus, but the cells on the side next the
receptacle are smaller than those on the external wall (fig. 309, A). The
synangial form of the sorus suggests comparison with Marattiaceae.
The species described by Renault from the Culm of Esnost is regarded by
P. Bertrand as identical with that described by Solms, from the Culm of
Falkenberg, as Zygopteris Roemeri[1138]. Diplolabis is compared by P.
Bertrand with Metaclepsydropsis, the generic name given to the Lower
Carboniferous petiole described by Williamson as Rachiopteris duplex[1139].
Mr Gordon has recently described in a preliminary note a new type of
stem stele under the name Zygopteris pettycurensis from the Lower
Carboniferous plant bed of Pettycur[1140]: he regards the petioles attached to
the stem as identical with Zygopteris Roemeri Solms-Laubach[1141]. This
species, founded by Solms-Laubach on petioles only, is placed by
Bertrand[1142] in the genus Diplolabis and regarded as identical with D.
esnostensis Ren. The stele found by Mr Gordon may therefore be assigned
to the genus Diplolabis: it includes two regions composed exclusively of
tracheae and is cylindrical in transverse section. The inner xylem zone
Page 493
consists of short, square-ended, reticulately pitted elements and the outer
zone is composed of long and pointed conducting tracheae. The scalariform
protoxylem elements are situated between the two metaxylem zones. As Mr
Gordon says: this type of stem occupies a position “in the Zygopteroid
alliance” corresponding to that which Thamnopteris Schlechtendalii (p.
329) occupies in the Osmundaceous series. The discovery of this stem
supplies another link between the two fern groups, Osmundaceae and
Coenopterideae. Pelourde[1143] has described an imperfectly preserved
vascular strand from a locality near Autun as the type of a new genus
Flicheia esnostensis. Mr Gordon has pointed out to me that this is a
partially rotted petiole of Diplolabis esnostensis (= Zygopteris Roemeri).
In their recent account of fossil Osmundaceous genera, Kidston and
Gwynne-Vaughan[1144] speak of the central parenchyma of the existing
medullated stele as being derived from tracheal tissue. They add that if the
Zygopteroid line of descent is at all close to the Osmundaceous, we must be
prepared for the existence of a Zygopteris with a solid xylem like that of
Thamnopteris: “such a discovery, in fact, we hopefully anticipate[1145].” The
new Pettycur stem amply justifies this prophecy. It is noteworthy that Mr
Gordon’s stem affords an instance of the occurrence of a type of stele,
similar in its cylindrical form and in the absence of parenchyma to that of
Botryopteris, in a plant bearing leaves characterised by the Zygopteris type
of vascular strand.
Metaclepsydropsis duplex (Will.) fig. 310, A[1146]. [= Rachiopteris duplex,
Williamson 1874. Asterochlaena (Clepsydropsis) duplex, Stenzel 1889.
Clepsydropsis, Renault 1896.]
The vascular axis of the main axis of the frond is characterised by the
hour-glass shape of the xylem which consists entirely of tracheae, most of
which are reticulately pitted. In a transverse section (fig. 310, A) the two
ends of the stele are dissimilar; at one end of the long axis is a small bay of
thin-walled tissue (phloem) enclosed by a narrow band of xylem, and at the
other the bay is open and has two protoxylem groups. The latter represents
the earliest stage in the production of secondary bundles: at a later stage the
bay is closed by the elongation of the edges, the enclosed group of phloem
is vertically extended, and the protoxylem strands are more widely
separated. The curved band of xylem becomes detached as a curved arc and
zone is composed of long and pointed conducting tracheae. The scalariform
protoxylem elements are situated between the two metaxylem zones. As Mr
Gordon says: this type of stem occupies a position “in the Zygopteroid
alliance” corresponding to that which Thamnopteris Schlechtendalii (p.
329) occupies in the Osmundaceous series. The discovery of this stem
supplies another link between the two fern groups, Osmundaceae and
Coenopterideae. Pelourde[1143] has described an imperfectly preserved
vascular strand from a locality near Autun as the type of a new genus
Flicheia esnostensis. Mr Gordon has pointed out to me that this is a
partially rotted petiole of Diplolabis esnostensis (= Zygopteris Roemeri).
In their recent account of fossil Osmundaceous genera, Kidston and
Gwynne-Vaughan[1144] speak of the central parenchyma of the existing
medullated stele as being derived from tracheal tissue. They add that if the
Zygopteroid line of descent is at all close to the Osmundaceous, we must be
prepared for the existence of a Zygopteris with a solid xylem like that of
Thamnopteris: “such a discovery, in fact, we hopefully anticipate[1145].” The
new Pettycur stem amply justifies this prophecy. It is noteworthy that Mr
Gordon’s stem affords an instance of the occurrence of a type of stele,
similar in its cylindrical form and in the absence of parenchyma to that of
Botryopteris, in a plant bearing leaves characterised by the Zygopteris type
of vascular strand.
Metaclepsydropsis duplex (Will.) fig. 310, A[1146]. [= Rachiopteris duplex,
Williamson 1874. Asterochlaena (Clepsydropsis) duplex, Stenzel 1889.
Clepsydropsis, Renault 1896.]
The vascular axis of the main axis of the frond is characterised by the
hour-glass shape of the xylem which consists entirely of tracheae, most of
which are reticulately pitted. In a transverse section (fig. 310, A) the two
ends of the stele are dissimilar; at one end of the long axis is a small bay of
thin-walled tissue (phloem) enclosed by a narrow band of xylem, and at the
other the bay is open and has two protoxylem groups. The latter represents
the earliest stage in the production of secondary bundles: at a later stage the
bay is closed by the elongation of the edges, the enclosed group of phloem
is vertically extended, and the protoxylem strands are more widely
separated. The curved band of xylem becomes detached as a curved arc and
Page 494
divides into two (fig. 310, A). In a single section of this species one often
sees several strands of xylem enclosed in a common cortex with the main
vascular axis; these are the xylem bundles of lateral pinnae.
Metaclepsydropsis duplex shows the method of branching of the petiole
vascular axis which has already been noticed in Diplolabis and Zygopteris.
In reference to this feature, Williamson wrote in 1872—“I know of no
recent fern in which the secondary branches of the petiole are thus given off
in pairs, which pairs are distichously arranged on the primary axis, and each
of which secondary petioles sustains ternary ones arranged distichously.”
By slightly altering the primary stele of this type of frond, by narrowing of
the constricted portion of the hour-glass and extending the lateral groups of
xylem obliquely upwards, the form of stele shown in fig. 310, A, would be
converted into the Diplolabis type (fig. 308, C).
Clepsydropsis.
Unger[1147] instituted this genus as a subdivision of Corda’s family
Rhaciopterideae[1148], the name having reference to the hour-glass form of
the vascular axis[1149]. The type-species C. antiqua (fig. 308, A) is spoken of
as the commonest fossil plant in the Devonian rocks of Thuringia. In some
sections the xylem has the form seen in fig. 308, A, in which an
invagination of thin-walled tissue occurs at each end; in other sections (fig.
308, A′) the bays become islands in the xylem. Solms-Laubach speaks of
Unger’s species as Rachiopteris (Clepsydropsis) antiqua. P. Bertrand[1150],
who has recently described Unger’s plant, while recognising that C. antiqua
and Metaclepsydropsis duplex closely resemble one another, draws
attention to certain differences in the structure of the xylem which he
regards as sufficient to justify a generic separation. The leaf-traces of
Clepsydropsis are described by Bertrand as almost circular closed rings of
xylem instead of an arc as in Metaclepsydropsis.
sees several strands of xylem enclosed in a common cortex with the main
vascular axis; these are the xylem bundles of lateral pinnae.
Metaclepsydropsis duplex shows the method of branching of the petiole
vascular axis which has already been noticed in Diplolabis and Zygopteris.
In reference to this feature, Williamson wrote in 1872—“I know of no
recent fern in which the secondary branches of the petiole are thus given off
in pairs, which pairs are distichously arranged on the primary axis, and each
of which secondary petioles sustains ternary ones arranged distichously.”
By slightly altering the primary stele of this type of frond, by narrowing of
the constricted portion of the hour-glass and extending the lateral groups of
xylem obliquely upwards, the form of stele shown in fig. 310, A, would be
converted into the Diplolabis type (fig. 308, C).
Clepsydropsis.
Unger[1147] instituted this genus as a subdivision of Corda’s family
Rhaciopterideae[1148], the name having reference to the hour-glass form of
the vascular axis[1149]. The type-species C. antiqua (fig. 308, A) is spoken of
as the commonest fossil plant in the Devonian rocks of Thuringia. In some
sections the xylem has the form seen in fig. 308, A, in which an
invagination of thin-walled tissue occurs at each end; in other sections (fig.
308, A′) the bays become islands in the xylem. Solms-Laubach speaks of
Unger’s species as Rachiopteris (Clepsydropsis) antiqua. P. Bertrand[1150],
who has recently described Unger’s plant, while recognising that C. antiqua
and Metaclepsydropsis duplex closely resemble one another, draws
attention to certain differences in the structure of the xylem which he
regards as sufficient to justify a generic separation. The leaf-traces of
Clepsydropsis are described by Bertrand as almost circular closed rings of
xylem instead of an arc as in Metaclepsydropsis.
Page 495
Fig. 310.
A. Metaclepsydropsis duplex.
B, C. Stauropteris oldhamia.
D. Ankyropteris scandens.
[A, from a section in Dr Kidston’s Collection (Lower Carboniferous); B, C, from sections in
the Cambridge Botany School; D, after Stenzel.]
Ankyropteris.
Stenzel adopted this name for a subdivision of Corda’s genus Zygopteris,
applying it to a species described by Renault as Z. Brongniarti, to a Permian
species described by himself as Z. (Ankyropteris) scandens, and to Z.
Lacattii Ren.; Rachiopteris Grayi Will. and Rachiopteris corrugata Will.
are also included in this genus. The characters emphasised by Stenzel[1151]
are (i) the double anchor-like form of the H-shaped petiole strand in which
the lateral arms (antennae) are curved like the flukes of an anchor, and (ii)
the emission of four rows of branches instead of two. The latter
distinguishing feature no longer holds good, as Z. primaria also gives off
four rows of bundles and not two as Stenzel supposed. P. Bertrand has
adopted Stenzel’s genus in a narrower sense[1152].
A. Metaclepsydropsis duplex.
B, C. Stauropteris oldhamia.
D. Ankyropteris scandens.
[A, from a section in Dr Kidston’s Collection (Lower Carboniferous); B, C, from sections in
the Cambridge Botany School; D, after Stenzel.]
Ankyropteris.
Stenzel adopted this name for a subdivision of Corda’s genus Zygopteris,
applying it to a species described by Renault as Z. Brongniarti, to a Permian
species described by himself as Z. (Ankyropteris) scandens, and to Z.
Lacattii Ren.; Rachiopteris Grayi Will. and Rachiopteris corrugata Will.
are also included in this genus. The characters emphasised by Stenzel[1151]
are (i) the double anchor-like form of the H-shaped petiole strand in which
the lateral arms (antennae) are curved like the flukes of an anchor, and (ii)
the emission of four rows of branches instead of two. The latter
distinguishing feature no longer holds good, as Z. primaria also gives off
four rows of bundles and not two as Stenzel supposed. P. Bertrand has
adopted Stenzel’s genus in a narrower sense[1152].
Page 496
Fig. 311. Ankyropteris Grayi. Stele. (From a section in Dr Kidston’s Collection, × 18.)
Ankyropteris scandens Stenzel[1153]. Fig. 310, D.
This Lower Permian species is very similar to or perhaps identical with
Ankyropteris Grayi (Williamson). The stem of
A. scandens was found in association with the roots of a Psaronius stem
evidently petrified in situ as it burrowed, like Tmesipteris, tropical aroids,
and other recent plants, among the living roots of the tree-fern. The stem,
10–11 mm. in diameter, bore fronds with an H-shaped vascular strand,
small scale-leaves, and adventitious roots. The stele consists of a five-
angled cylinder of scalariform tracheae surrounding an axial strand of
parenchyma containing scattered tracheae of smaller diameter. This axial
tissue extends as a narrow strip into each of the short and obtusely truncated
arms (cf. fig. 311). A striking feature is the production of a shoot in the axil
Ankyropteris scandens Stenzel[1153]. Fig. 310, D.
This Lower Permian species is very similar to or perhaps identical with
Ankyropteris Grayi (Williamson). The stem of
A. scandens was found in association with the roots of a Psaronius stem
evidently petrified in situ as it burrowed, like Tmesipteris, tropical aroids,
and other recent plants, among the living roots of the tree-fern. The stem,
10–11 mm. in diameter, bore fronds with an H-shaped vascular strand,
small scale-leaves, and adventitious roots. The stele consists of a five-
angled cylinder of scalariform tracheae surrounding an axial strand of
parenchyma containing scattered tracheae of smaller diameter. This axial
tissue extends as a narrow strip into each of the short and obtusely truncated
arms (cf. fig. 311). A striking feature is the production of a shoot in the axil
Page 497
of the foliage-leaves (fig. 310, D), a manner of branching characteristic of
Trichomanes (see page 365).
Ankyropteris Grayi (Will.). Fig. 311.
In describing this species, Williamson wrote—“That no classification of
these fossil ferns based solely upon transverse sections of the petiolar
bundles is or can be of much value, is clearly shown when tested amongst
those living ferns the classification of which is chiefly based upon the
sporangial reproductive organs[1154].” This is a view entirely opposed to that
which inspires P. Bertrand’s recent monograph. Whether the value attached
to the vascular structure of petioles as a basis of classification is upheld or
not, it is noteworthy that since Williamson expressed his opinion, our
knowledge of the anatomy of ferns and of the value of anatomical evidence
has enormously increased. The slender stem[1155] of this Lower Coal-
Measures species agrees closely with that of A. scandens; it bore spirally
disposed fronds, scale-leaves, and roots. The stele has the form of an
irregular five-rayed star (fig. 311) in which the relative length of the arms
varies in different sections owing to the separation of the distal ends to form
leaf-traces. The axial region is composed of parenchyma and associated
narrow tracheae, as in A. scandens. The xylem, with protoxylem elements at
the ends and especially at the angles of the arms, is completely surrounded
by phloem. The cortex consists internally of parenchyma which becomes
thicker-walled towards the periphery and bears multicellular epidermal
hairs. A leaf-trace is detached in the form of a triangular strand and is
formed by the tangential extension of the distal end of an arm of the stele.
The trace, on its way through the cortex, divides into two; the outer branch
gradually changes from a slightly curved band to an H-shaped meristele;
the inner branch, which supplied an axillary shoot, is similar to the stele of
the stem, but smaller. Scott[1156] has recently recorded the occurrence of
scale-leaves (aphlebiae) in this species like those described by Stenzel in A.
scandens.
Trichomanes (see page 365).
Ankyropteris Grayi (Will.). Fig. 311.
In describing this species, Williamson wrote—“That no classification of
these fossil ferns based solely upon transverse sections of the petiolar
bundles is or can be of much value, is clearly shown when tested amongst
those living ferns the classification of which is chiefly based upon the
sporangial reproductive organs[1154].” This is a view entirely opposed to that
which inspires P. Bertrand’s recent monograph. Whether the value attached
to the vascular structure of petioles as a basis of classification is upheld or
not, it is noteworthy that since Williamson expressed his opinion, our
knowledge of the anatomy of ferns and of the value of anatomical evidence
has enormously increased. The slender stem[1155] of this Lower Coal-
Measures species agrees closely with that of A. scandens; it bore spirally
disposed fronds, scale-leaves, and roots. The stele has the form of an
irregular five-rayed star (fig. 311) in which the relative length of the arms
varies in different sections owing to the separation of the distal ends to form
leaf-traces. The axial region is composed of parenchyma and associated
narrow tracheae, as in A. scandens. The xylem, with protoxylem elements at
the ends and especially at the angles of the arms, is completely surrounded
by phloem. The cortex consists internally of parenchyma which becomes
thicker-walled towards the periphery and bears multicellular epidermal
hairs. A leaf-trace is detached in the form of a triangular strand and is
formed by the tangential extension of the distal end of an arm of the stele.
The trace, on its way through the cortex, divides into two; the outer branch
gradually changes from a slightly curved band to an H-shaped meristele;
the inner branch, which supplied an axillary shoot, is similar to the stele of
the stem, but smaller. Scott[1156] has recently recorded the occurrence of
scale-leaves (aphlebiae) in this species like those described by Stenzel in A.
scandens.
Page 498
Fig. 312.
A. Thamnopteris Schlechtendalii. Leaf-trace: px, protoxylem; s, island of
parenchyma. (After Kidston and Gwynne-Vaughan.)
B. Ankyropteris corrugata. Single trachea with tyloses.
C. A. bibractensis. Part of foliar strand. (After P. Bertrand.)
Bertrand includes in Ankyropteris Renault’s species Zygopteris
bibractensis[1157] and Williamson’s species Rachiopteris corrugata[1158]: the
former he names A. bibractensis var. westphaliensis. The fossil described
by Williamson as R. irregularis or inaequalis[1159] are the secondary
branches of A. bibractensis.
Ankyropteris bibractensis, var. westphaliensis. Figs. 312, C; 313.
The rachis stele of this species, which is represented by portions of
fronds only, has the form of a double anchor (fig. 313); the antennae are
continued at the outer edge of their distal ends into a narrow band
(“filament” of P. Bertrand) (fig. 312, C, and 313, a) composed of smaller
tracheae and separated from the xylem of the antennae by a strip of thin-
walled tissue (phloem?). A group of protoxylem occurs at the junction of
A. Thamnopteris Schlechtendalii. Leaf-trace: px, protoxylem; s, island of
parenchyma. (After Kidston and Gwynne-Vaughan.)
B. Ankyropteris corrugata. Single trachea with tyloses.
C. A. bibractensis. Part of foliar strand. (After P. Bertrand.)
Bertrand includes in Ankyropteris Renault’s species Zygopteris
bibractensis[1157] and Williamson’s species Rachiopteris corrugata[1158]: the
former he names A. bibractensis var. westphaliensis. The fossil described
by Williamson as R. irregularis or inaequalis[1159] are the secondary
branches of A. bibractensis.
Ankyropteris bibractensis, var. westphaliensis. Figs. 312, C; 313.
The rachis stele of this species, which is represented by portions of
fronds only, has the form of a double anchor (fig. 313); the antennae are
continued at the outer edge of their distal ends into a narrow band
(“filament” of P. Bertrand) (fig. 312, C, and 313, a) composed of smaller
tracheae and separated from the xylem of the antennae by a strip of thin-
walled tissue (phloem?). A group of protoxylem occurs at the junction of
Page 499
the filament and antennae. The whole of the xylem is surrounded by
phloem.
Fig. 313. Ankyropteris bibractensis: s, stigmarian rootlet; a, narrow loop of xylem.
(Cambridge Botany School; × 6).
The section reproduced in fig. 313 shows the characteristic form of the
petiolar vascular axis, consisting of a horizontal band of metaxylem with
groups of much smaller tracheae on both the upper and lower margins. At
the junction between the antennae, curved like the flukes of an anchor, and
the horizontal band of xylem, the latter is only one trachea in breadth. The
narrow loops of smaller xylem elements are shown on the outer edge, a (fig.
313), of the antennae separated from the arcs of larger tracheae by a dark
line which represents a crushed band of delicate tissue. The spaces enclosed
by the incurved antennae are largely occupied by parenchymatous ground-
tissue. The cylinder of outer cortex consists internally of comparatively
thin-walled parenchyma succeeded externally by a zone of dark and thicker-
walled cells characterised by a fairly regular arrangement in radial series, as
if formed by a secondary meristem; there is, however, no indication of a
meristematic layer. Below the small-celled epidermis are a few layers of
thinner-walled cells which are not arranged in radial series. The structure of
the outer part of the cortex is similar to that in the petiole of recent species
of Angiopteris (fig. 243, p. 319) and Marattia, in which a more delicate
hypoderm is succeeded by a band of mechanical tissue.
phloem.
Fig. 313. Ankyropteris bibractensis: s, stigmarian rootlet; a, narrow loop of xylem.
(Cambridge Botany School; × 6).
The section reproduced in fig. 313 shows the characteristic form of the
petiolar vascular axis, consisting of a horizontal band of metaxylem with
groups of much smaller tracheae on both the upper and lower margins. At
the junction between the antennae, curved like the flukes of an anchor, and
the horizontal band of xylem, the latter is only one trachea in breadth. The
narrow loops of smaller xylem elements are shown on the outer edge, a (fig.
313), of the antennae separated from the arcs of larger tracheae by a dark
line which represents a crushed band of delicate tissue. The spaces enclosed
by the incurved antennae are largely occupied by parenchymatous ground-
tissue. The cylinder of outer cortex consists internally of comparatively
thin-walled parenchyma succeeded externally by a zone of dark and thicker-
walled cells characterised by a fairly regular arrangement in radial series, as
if formed by a secondary meristem; there is, however, no indication of a
meristematic layer. Below the small-celled epidermis are a few layers of
thinner-walled cells which are not arranged in radial series. The structure of
the outer part of the cortex is similar to that in the petiole of recent species
of Angiopteris (fig. 243, p. 319) and Marattia, in which a more delicate
hypoderm is succeeded by a band of mechanical tissue.
Page 500
The rachis of this type of frond gives off two rows of lateral branches
from the vascular axis, the plane of symmetry being at right angles to the
primary rachis. Each pinna bore at its base two aphlebiae supplied with
vascular strands from the leaf-traces.
We have no certain information in regard to the sporangia of this species,
but Scott points out that “pear-shaped sporangia, with a very broad and
extensive annulus, are commonly found associated with Zygopteris
bibractensis and Z. corrugata in the petrifactions of the English Lower
Coal-Measures[1160].”
Ankyropteris corrugata (Will.). Figs. 312, B; 314–317.
The stem of this type of Zygoptereae was described by Williamson from
the Lower Coal-Measures of Lancashire as Rachiopteris corrugata and
included by him in the sub-group Anachoropteroides. The stele (fig. 314, B)
is oval in transverse section; it consists of a cylinder of xylem tracheae
enclosing a central region occupied by parenchymatous tissue and scattered
narrow scalariform tracheae. The central tissue extends radially in the form
of narrow arms which reach almost to the outer edge of the tracheal tissue
and divide it up into 5–7 groups. A cylinder of thin-walled tissue encloses
the xylem and in this occur groups of large sieve-tubes (fig. 314, D, Sv).
In a section of this species in the Williamson Collection[1161] the long axis
of the stele has a length of 5 mm. and the diameter of the stem as a whole is
2·5 cm. The greater part of the extra-stelar tissue consists of large
parenchymatous cells passing near the periphery into a band of darker and
thicker-walled tissue.
Reniform vascular strands traverse the cortex in an obliquely ascending
course on their way to the leaves, also smaller bundles, some of which are
given off directly from the stele, while others are branches of the petiole
vascular strands. The petioles described by Williamson as Rachiopteris
insignis[1162] were afterwards recognised by him as those of Ankyropteris
corrugata, though this conclusion was not published[1163]. Williamson’s
species R. insignis must not be confused with Unger’s Culm species
Arctopodium insigne, which Solms-Laubach[1164] refers to as Rachiopteris
insignis. The leaf-bundle of Ankyropteris corrugata is at first reniform in
contour (fig. 314, C, P), but as it becomes free from the stem it gradually
from the vascular axis, the plane of symmetry being at right angles to the
primary rachis. Each pinna bore at its base two aphlebiae supplied with
vascular strands from the leaf-traces.
We have no certain information in regard to the sporangia of this species,
but Scott points out that “pear-shaped sporangia, with a very broad and
extensive annulus, are commonly found associated with Zygopteris
bibractensis and Z. corrugata in the petrifactions of the English Lower
Coal-Measures[1160].”
Ankyropteris corrugata (Will.). Figs. 312, B; 314–317.
The stem of this type of Zygoptereae was described by Williamson from
the Lower Coal-Measures of Lancashire as Rachiopteris corrugata and
included by him in the sub-group Anachoropteroides. The stele (fig. 314, B)
is oval in transverse section; it consists of a cylinder of xylem tracheae
enclosing a central region occupied by parenchymatous tissue and scattered
narrow scalariform tracheae. The central tissue extends radially in the form
of narrow arms which reach almost to the outer edge of the tracheal tissue
and divide it up into 5–7 groups. A cylinder of thin-walled tissue encloses
the xylem and in this occur groups of large sieve-tubes (fig. 314, D, Sv).
In a section of this species in the Williamson Collection[1161] the long axis
of the stele has a length of 5 mm. and the diameter of the stem as a whole is
2·5 cm. The greater part of the extra-stelar tissue consists of large
parenchymatous cells passing near the periphery into a band of darker and
thicker-walled tissue.
Reniform vascular strands traverse the cortex in an obliquely ascending
course on their way to the leaves, also smaller bundles, some of which are
given off directly from the stele, while others are branches of the petiole
vascular strands. The petioles described by Williamson as Rachiopteris
insignis[1162] were afterwards recognised by him as those of Ankyropteris
corrugata, though this conclusion was not published[1163]. Williamson’s
species R. insignis must not be confused with Unger’s Culm species
Arctopodium insigne, which Solms-Laubach[1164] refers to as Rachiopteris
insignis. The leaf-bundle of Ankyropteris corrugata is at first reniform in
contour (fig. 314, C, P), but as it becomes free from the stem it gradually
Page 501
assumes the H-shaped form (figs. 315–317). This petiolar strand differs
from that of Ankyropteris bibractensis (fig. 313) in the shorter and less
strongly curved antennae; and, as Williamson first noticed, the tracheae are
frequently filled with thin-walled parenchyma (fig. 312, B). The existence
of scale-leaves or aphlebiae like those of Ankyropteris scandens and A.
Grayi has been recorded by Scott in A. corrugata[1165].
The section represented in fig. 314, C, shows the relatively small size of
the stele S in the stem of Ankyropteris corrugata. The main mass of the
cortex consists of uniform parenchyma passing near the surface into darker
and stronger tissue: two vascular bundles are shown in the cortex, one of
which forms the conducting strand of a petiole, P, which has nearly freed
itself from the stem: the other bundle, as shown by the examination of a
series of sections, eventually passes into another leaf-stalk. A root of
another plant has invaded the cortex at R, fig. 314, C.
from that of Ankyropteris bibractensis (fig. 313) in the shorter and less
strongly curved antennae; and, as Williamson first noticed, the tracheae are
frequently filled with thin-walled parenchyma (fig. 312, B). The existence
of scale-leaves or aphlebiae like those of Ankyropteris scandens and A.
Grayi has been recorded by Scott in A. corrugata[1165].
The section represented in fig. 314, C, shows the relatively small size of
the stele S in the stem of Ankyropteris corrugata. The main mass of the
cortex consists of uniform parenchyma passing near the surface into darker
and stronger tissue: two vascular bundles are shown in the cortex, one of
which forms the conducting strand of a petiole, P, which has nearly freed
itself from the stem: the other bundle, as shown by the examination of a
series of sections, eventually passes into another leaf-stalk. A root of
another plant has invaded the cortex at R, fig. 314, C.
Page 502
Fig. 314. Ankyropteris corrugata. R, intruded root; P, petiole; S, stele, Sv sieve-tubes.
A, B. From a section in the University College Collection.
C. After Williamson.
D. From a section in the Williamson Collection (British Museum).
The form and structure of the stele is diagrammatically represented in fig.
314, B. The outer portion (black) consists of a cylinder of scalariform
tracheae in which the position of groups of smaller elements (protoxylem)
is shown by the white patches. The xylem is thus seen to be mesarch. The
prominent group of xylem on the lower right-hand side of the section
consists of tracheae, cut across in an oblique direction, which are about to
pass out as a separate strand. The centre of the stele is occupied by
A, B. From a section in the University College Collection.
C. After Williamson.
D. From a section in the Williamson Collection (British Museum).
The form and structure of the stele is diagrammatically represented in fig.
314, B. The outer portion (black) consists of a cylinder of scalariform
tracheae in which the position of groups of smaller elements (protoxylem)
is shown by the white patches. The xylem is thus seen to be mesarch. The
prominent group of xylem on the lower right-hand side of the section
consists of tracheae, cut across in an oblique direction, which are about to
pass out as a separate strand. The centre of the stele is occupied by
Page 503
parenchymatous tissue in which are included scattered tracheae, either
singly or in small groups. These medullary tracheae are rather narrower
than those of the main xylem cylinder. A characteristic feature is the radial
outward extension into the xylem of the medullary parenchyma, which
tends partially to divide the tracheal cylinder into broad groups.
Fig. 315. Ankyropteris corrugata (Will.). Petiolar vascular strand. [From a section in the
University College (London) Collection; after Tansley × 35.]
Fig. 314, A, enlarged from fig. B, a, shows the mesarch position of a
protoxylem group, and a few of the parenchymatous cells of one of the
narrow arms of the axial tissue. At Sv in fig. D a group of large sieve-tubes
is seen separated from the xylem by a few parenchymatous cells, and
beyond the sieve-tubes are some tangentially elongated cells. Both the
sieve-tubes, Sv, and the flattened cells resemble tissues in a corresponding
position in the steles of modern Osmundaceae.
singly or in small groups. These medullary tracheae are rather narrower
than those of the main xylem cylinder. A characteristic feature is the radial
outward extension into the xylem of the medullary parenchyma, which
tends partially to divide the tracheal cylinder into broad groups.
Fig. 315. Ankyropteris corrugata (Will.). Petiolar vascular strand. [From a section in the
University College (London) Collection; after Tansley × 35.]
Fig. 314, A, enlarged from fig. B, a, shows the mesarch position of a
protoxylem group, and a few of the parenchymatous cells of one of the
narrow arms of the axial tissue. At Sv in fig. D a group of large sieve-tubes
is seen separated from the xylem by a few parenchymatous cells, and
beyond the sieve-tubes are some tangentially elongated cells. Both the
sieve-tubes, Sv, and the flattened cells resemble tissues in a corresponding
position in the steles of modern Osmundaceae.
Page 504
In a section of Ankyropteris corrugata in the Williamson Collection the
radial arrangement of the more external metaxylem elements suggests the
addition of secondary tracheae[1166]. This suggestion of secondary
thickening, a point which requires much more thorough investigation, is
interesting in relation to a new type of stem named by Scott
Botrychioxylon[1167], but not yet fully described. This generic name has been
given to a stem stele which closely resembles that of Ankyropteris
corrugata except in the regular radial arrangement of the peripheral xylem
elements. The name Botrychioxylon was chosen by Scott because of the
secondary xylem characteristic of the recent genus Botrychium (fig. 247, p.
322).
Fig. 316. Ankyropteris corrugata. Petiole. a, narrow xylem loop; b, spaces in cortex. From a
section in the Cambridge Botany School Collection. (× 10.)
In the petiolar vascular strand represented in fig. 315 the narrow band of
tracheae which forms a loop external to the antennae is clearly seen, also
the small-celled parenchyma between the loops and the larger metaxylem
elements of the antennae. The crushed tissue lying on the outer face of each
of the loops probably represents the phloem and pericycle; the thin-walled
elements above and below the horizontal band of metaxylem are probably
sieve-tubes.
radial arrangement of the more external metaxylem elements suggests the
addition of secondary tracheae[1166]. This suggestion of secondary
thickening, a point which requires much more thorough investigation, is
interesting in relation to a new type of stem named by Scott
Botrychioxylon[1167], but not yet fully described. This generic name has been
given to a stem stele which closely resembles that of Ankyropteris
corrugata except in the regular radial arrangement of the peripheral xylem
elements. The name Botrychioxylon was chosen by Scott because of the
secondary xylem characteristic of the recent genus Botrychium (fig. 247, p.
322).
Fig. 316. Ankyropteris corrugata. Petiole. a, narrow xylem loop; b, spaces in cortex. From a
section in the Cambridge Botany School Collection. (× 10.)
In the petiolar vascular strand represented in fig. 315 the narrow band of
tracheae which forms a loop external to the antennae is clearly seen, also
the small-celled parenchyma between the loops and the larger metaxylem
elements of the antennae. The crushed tissue lying on the outer face of each
of the loops probably represents the phloem and pericycle; the thin-walled
elements above and below the horizontal band of metaxylem are probably
sieve-tubes.
Page 505
Fig. 316 shows a transverse section of a petiole of this species: the loops,
a, of small tracheae are seen bending round the outer edge of the antennae.
The inner and more delicate cortical tissue is partially preserved and spaces,
b, have been formed in it as the result of contraction previous to
petrifaction. In the petiole represented in fig. 317 the tracheae of the
horizontal band are considerably crushed; the section is, however, of
interest because of the presence of Lyginodendron roots, l, in the space
originally occupied by the inner cortex.
Fig. 317. Ankyropteris corrugata. From a section in the Cambridge Botany School
Collection. (× 9.)
In a paper on the tyloses of Rachiopteris corrugata, Weiss[1168] draws
attention to the fact that similar inclusions have not been found in the
tracheae of recent ferns. The occurrence of thin-walled parenchymatous
cells in the large tracheae of Ankyropteris corrugata petioles and of other
species is a striking feature. Williamson[1169] compared these cells with the
tyloses in the vessels of recent flowering plants, and in a later paper[1170] he
suggested that the included cells may belong to saprophytic or parasitic
fungi. It is, as Weiss points out, difficult to explain the occurrence of tyloses
in tracheae not immediately in contact with living parenchyma. It may be
that the pits in the tracheae of Ankyropteris were open spaces as in the
xylem of recent ferns described by Gwynne-Vaughan, and if so this would
facilitate the invasion of the conducting elements by growing cells. A
comparison is made by Weiss between certain cell-groups found by him in
the tracheae of Ankyropteris and by Miss Jordan[1171] in the vessels of the
recent dicotyledon Cucumis sativus. In a more recent paper on tyloses Miss
a, of small tracheae are seen bending round the outer edge of the antennae.
The inner and more delicate cortical tissue is partially preserved and spaces,
b, have been formed in it as the result of contraction previous to
petrifaction. In the petiole represented in fig. 317 the tracheae of the
horizontal band are considerably crushed; the section is, however, of
interest because of the presence of Lyginodendron roots, l, in the space
originally occupied by the inner cortex.
Fig. 317. Ankyropteris corrugata. From a section in the Cambridge Botany School
Collection. (× 9.)
In a paper on the tyloses of Rachiopteris corrugata, Weiss[1168] draws
attention to the fact that similar inclusions have not been found in the
tracheae of recent ferns. The occurrence of thin-walled parenchymatous
cells in the large tracheae of Ankyropteris corrugata petioles and of other
species is a striking feature. Williamson[1169] compared these cells with the
tyloses in the vessels of recent flowering plants, and in a later paper[1170] he
suggested that the included cells may belong to saprophytic or parasitic
fungi. It is, as Weiss points out, difficult to explain the occurrence of tyloses
in tracheae not immediately in contact with living parenchyma. It may be
that the pits in the tracheae of Ankyropteris were open spaces as in the
xylem of recent ferns described by Gwynne-Vaughan, and if so this would
facilitate the invasion of the conducting elements by growing cells. A
comparison is made by Weiss between certain cell-groups found by him in
the tracheae of Ankyropteris and by Miss Jordan[1171] in the vessels of the
recent dicotyledon Cucumis sativus. In a more recent paper on tyloses Miss
Page 506
McNicol[1172] expresses the opinion that pseudoparenchyma in the tracheae
of the fossil petioles owes its origin to fungal hyphae.
Williamson compared the petiole bundles of Ankyropteris corrugata with
those of recent Osmundaceae, a comparison based on the structure of the
leaf-trace before its separation from the stem and its assumption of the H-
form. It is noteworthy, however, that this comparison has acquired a greater
significance as the result of recent work. The stele of Ankyropteris bears a
fairly close resemblance to that of Zalesskya described by Kidston and
Gwynne-Vaughan; in both types the xylem is represented by two kinds of
tracheal tissue. In the Permian Osmundaceous genus the centre of the stele
consists of short storage tracheids, while in Ankyropteris we may regard the
central parenchyma and scattered tracheae as derivatives of the solid xylem
core of some ancestral type. Moreover, the appearance and arrangement of
the phloem and the tangentially elongated elements external to it (fig. 314)
remind one of the extra-xylem zone in recent Osmundaceae. That the
Osmundaceae and Zygoptereae are closely related groups there can be little
doubt; of this affinity and common origin[1173] Ankyropteris corrugata
affords striking evidence.
The difference between the steles of Ankyropteris Grayi and A. scandens
(figs. 310, D; 311) and that of Ankyropteris corrugata is comparatively
small. In the two former species the cylindrical form has become stellate
owing to the radial extension of the xylem arms. It may be that this more
elaborate style of vascular construction is connected with the climbing habit
of A. scandens and possibly A. Grayi. The radial extension of the xylem and
the consequent alternation of the yielding parenchymatous cortex and the
more rigid tracheal arms would probably render the water-conducting
elements less liable to injury in a twisting axis[1174]. In Anachoropteris
Decaisnii[1175], described by Renault, and more especially in Asterochlaena
laxa[1176] Stenzel, a Lower Permian type from Saxony (fig. 324), the xylem
of the stele is much more deeply lobed than in Ankyropteris Grayi or A.
scandens.
of the fossil petioles owes its origin to fungal hyphae.
Williamson compared the petiole bundles of Ankyropteris corrugata with
those of recent Osmundaceae, a comparison based on the structure of the
leaf-trace before its separation from the stem and its assumption of the H-
form. It is noteworthy, however, that this comparison has acquired a greater
significance as the result of recent work. The stele of Ankyropteris bears a
fairly close resemblance to that of Zalesskya described by Kidston and
Gwynne-Vaughan; in both types the xylem is represented by two kinds of
tracheal tissue. In the Permian Osmundaceous genus the centre of the stele
consists of short storage tracheids, while in Ankyropteris we may regard the
central parenchyma and scattered tracheae as derivatives of the solid xylem
core of some ancestral type. Moreover, the appearance and arrangement of
the phloem and the tangentially elongated elements external to it (fig. 314)
remind one of the extra-xylem zone in recent Osmundaceae. That the
Osmundaceae and Zygoptereae are closely related groups there can be little
doubt; of this affinity and common origin[1173] Ankyropteris corrugata
affords striking evidence.
The difference between the steles of Ankyropteris Grayi and A. scandens
(figs. 310, D; 311) and that of Ankyropteris corrugata is comparatively
small. In the two former species the cylindrical form has become stellate
owing to the radial extension of the xylem arms. It may be that this more
elaborate style of vascular construction is connected with the climbing habit
of A. scandens and possibly A. Grayi. The radial extension of the xylem and
the consequent alternation of the yielding parenchymatous cortex and the
more rigid tracheal arms would probably render the water-conducting
elements less liable to injury in a twisting axis[1174]. In Anachoropteris
Decaisnii[1175], described by Renault, and more especially in Asterochlaena
laxa[1176] Stenzel, a Lower Permian type from Saxony (fig. 324), the xylem
of the stele is much more deeply lobed than in Ankyropteris Grayi or A.
scandens.
Page 507
Fig. 318. Etapteris Scotti, P. Bert. (From Tansley, after Renault.)
Etapteris Scotti. Figs. 308, B; 309, E; 318.
P. Bertrand has proposed this name for a species of petiole from the
Lower Coal-Measures of England referred by Binney[1177] to Zygopteris
Lacattii Ren., and included by Williamson[1178] in his comprehensive genus
Rachiopteris. Bertrand[1179] regards the English species, which is recorded
also from Germany[1180], as distinct from Renault’s type[1181] and therefore
proposes a new name. The petiole stele has the H-form, but its structure is
simpler than that of the Ankyropteris petiole.
The horizontal band of xylem has at each end two oval groups of
tracheae connected with it by a single row of xylem elements (fig. 318).
From the lower part of each oval group a small strand is detached; the two
strands from one side of the stele coalesce and then separate to pass into
two pinnae. Fig. 308, B, shows four stages in the giving-off of the
secondary branches. This species, therefore, produces four rows of branches
in alternate pairs from the right and left sides of the petiole.
The first stage is shown at 0, 0, fig. 308, B; the two projecting groups of
protoxylem mark the points of departure of a pair of small strands. At 1, the
projections are more prominent, and at 2 a pair of strands has become
detached: at a later stage, 3, these two strands unite to divide later (4) into
two slightly curved bundles.
Etapteris Scotti. Figs. 308, B; 309, E; 318.
P. Bertrand has proposed this name for a species of petiole from the
Lower Coal-Measures of England referred by Binney[1177] to Zygopteris
Lacattii Ren., and included by Williamson[1178] in his comprehensive genus
Rachiopteris. Bertrand[1179] regards the English species, which is recorded
also from Germany[1180], as distinct from Renault’s type[1181] and therefore
proposes a new name. The petiole stele has the H-form, but its structure is
simpler than that of the Ankyropteris petiole.
The horizontal band of xylem has at each end two oval groups of
tracheae connected with it by a single row of xylem elements (fig. 318).
From the lower part of each oval group a small strand is detached; the two
strands from one side of the stele coalesce and then separate to pass into
two pinnae. Fig. 308, B, shows four stages in the giving-off of the
secondary branches. This species, therefore, produces four rows of branches
in alternate pairs from the right and left sides of the petiole.
The first stage is shown at 0, 0, fig. 308, B; the two projecting groups of
protoxylem mark the points of departure of a pair of small strands. At 1, the
projections are more prominent, and at 2 a pair of strands has become
detached: at a later stage, 3, these two strands unite to divide later (4) into
two slightly curved bundles.
Page 508
Fig. 319.
A–C. Sporangia of Etapteris (?).
D–G. Botryopteris forensis. (After Renault.)
Our knowledge of the fructification of Etapteris is based on Renault’s
account of sporangia, which he regarded as belonging to Zygopteris
(Etapteris) Lacattii. They have the form of elongated slightly curved sacs
(2·5 × 1·3 mm.) borne in clusters (fig. 319, A–C) on slender ramifications
of the fertile frond, which is characterised by the absence of a lamina. Each
sporangium has a pedicel, and three to eight sporangia are attached to a
common peduncle; the walls of the sporangia are at least two cell-layers in
thickness and the annulus consists of a band of thick-walled cells passing
from the crest down each side (figs. B and C), thus differing from the
sporangia of Botryopteris (fig. 319, D, F) in which the broad annulus is
confined to one side.
A–C. Sporangia of Etapteris (?).
D–G. Botryopteris forensis. (After Renault.)
Our knowledge of the fructification of Etapteris is based on Renault’s
account of sporangia, which he regarded as belonging to Zygopteris
(Etapteris) Lacattii. They have the form of elongated slightly curved sacs
(2·5 × 1·3 mm.) borne in clusters (fig. 319, A–C) on slender ramifications
of the fertile frond, which is characterised by the absence of a lamina. Each
sporangium has a pedicel, and three to eight sporangia are attached to a
common peduncle; the walls of the sporangia are at least two cell-layers in
thickness and the annulus consists of a band of thick-walled cells passing
from the crest down each side (figs. B and C), thus differing from the
sporangia of Botryopteris (fig. 319, D, F) in which the broad annulus is
confined to one side.
Page 509
Fig. 320. Stauropteris oldhamia. (After Tansley. From a section in Dr Scott’s Collection. ×
60.)
It is practically certain that the fronds described by Grand’Eury[1182] as
Schizopteris pinnata (fig. 309, E) and Schizostachys frondosus represent
respectively the sterile and fertile leaves of Etapteris. Zeiller[1183] gives
expression to this by substituting the generic name Zygopteris for
Schizopteris, and we may now speak of the leaves as Etapteris. Dr
White[1184] has referred to a new genus, Brittsia, some impressions of
pinnate fronds from the Coal-Measures of Missouri which, as he points out,
bear a close resemblance to Schizopteris pinnata Grand’Eury (fig. 309, E).
No sporangia have been found; it is, however, probable that Brittsia
problematica represents fragments of a leaf borne by a plant closely allied
to Etapteris (Zygopteris). The broad rachis bears crowded pinnae given off
at a wide angle; the small pinnules are rather deeply lobed or pinnatifid (3–
10 mm. long by 1·5–3 mm. broad). The lamina is traversed by irregularly
lobed and occasionally anastomosing veins. In the fertile pinnae the
segments have no lamina but bear bundles of pedicellate sporangia.
60.)
It is practically certain that the fronds described by Grand’Eury[1182] as
Schizopteris pinnata (fig. 309, E) and Schizostachys frondosus represent
respectively the sterile and fertile leaves of Etapteris. Zeiller[1183] gives
expression to this by substituting the generic name Zygopteris for
Schizopteris, and we may now speak of the leaves as Etapteris. Dr
White[1184] has referred to a new genus, Brittsia, some impressions of
pinnate fronds from the Coal-Measures of Missouri which, as he points out,
bear a close resemblance to Schizopteris pinnata Grand’Eury (fig. 309, E).
No sporangia have been found; it is, however, probable that Brittsia
problematica represents fragments of a leaf borne by a plant closely allied
to Etapteris (Zygopteris). The broad rachis bears crowded pinnae given off
at a wide angle; the small pinnules are rather deeply lobed or pinnatifid (3–
10 mm. long by 1·5–3 mm. broad). The lamina is traversed by irregularly
lobed and occasionally anastomosing veins. In the fertile pinnae the
segments have no lamina but bear bundles of pedicellate sporangia.
Page 510
It should be noticed that the sporangia described by Renault and by other
authors as those of Zygopteris (fig. 319, A–C) have not been found in
organic continuity with a frond showing a well-preserved vascular strand. It
is, however, certain that this characteristic annulate sporangium, borne on
branched and slender pedicels, was produced on fronds with a much
reduced lamina belonging to some species of the Zygoptereae, Etapteris
and probably also Ankyropteris.
Stauropteris.
This genus was instituted by Binney for petioles from the Lower Coal-
Measures of Oldham (Lancashire).
Stauropteris oldhamia Binney[1185] is characterised by a stele (figs. 308,
E–G; 310, C; 320; 321) composed of four groups of xylem which Bertrand
regards as homologous with the antennae of Diplolabis, Ankyropteris, and
Etapteris, the horizontal cross-piece of these genera being absent in
Stauropteris. Williamson spoke of this species as “one of the most beautiful
and also one of the most perplexing of the plants of the Coal-Measures”; he
discussed its possible affinity with both Lycopods and ferns, deciding in
favour of the latter group[1186]. In transverse section the petiolar vascular axis
is approximately square, the xylem groups forming the ends of the
diagonals; the tracheal groups are separated by phloem and the centre of the
stele in the primary rachis is also occupied by that tissue, which is
connected by four narrow strips with the external phloem. The structure of
the petiolar vascular axis is very clearly shown in the drawing by Mrs
Tansley reproduced in fig. 320. Protoxylem elements occur close to the
surface of each of the four arms of the xylem; the bays between the two
lateral and the two lower xylem groups contain large sieve-tubes. Portions
of the inner cortex are seen in places abutting on the small-celled pericyclic
tissue.
The right and left halves of the stele are not absolutely identical (fig. 320;
fig. 308, E); this is due to the fact that secondary branches are given off in
four rows, two alternately from the right and left sides. The preparation for
the departure of the lateral strands alters the configuration of the stelar
xylem groups. The protoxylem groups are not external but separated from
the surface by one or two layers of metaxylem. In fig. 308, E, the
occurrence of two protoxylem strands in the right-hand groups of
authors as those of Zygopteris (fig. 319, A–C) have not been found in
organic continuity with a frond showing a well-preserved vascular strand. It
is, however, certain that this characteristic annulate sporangium, borne on
branched and slender pedicels, was produced on fronds with a much
reduced lamina belonging to some species of the Zygoptereae, Etapteris
and probably also Ankyropteris.
Stauropteris.
This genus was instituted by Binney for petioles from the Lower Coal-
Measures of Oldham (Lancashire).
Stauropteris oldhamia Binney[1185] is characterised by a stele (figs. 308,
E–G; 310, C; 320; 321) composed of four groups of xylem which Bertrand
regards as homologous with the antennae of Diplolabis, Ankyropteris, and
Etapteris, the horizontal cross-piece of these genera being absent in
Stauropteris. Williamson spoke of this species as “one of the most beautiful
and also one of the most perplexing of the plants of the Coal-Measures”; he
discussed its possible affinity with both Lycopods and ferns, deciding in
favour of the latter group[1186]. In transverse section the petiolar vascular axis
is approximately square, the xylem groups forming the ends of the
diagonals; the tracheal groups are separated by phloem and the centre of the
stele in the primary rachis is also occupied by that tissue, which is
connected by four narrow strips with the external phloem. The structure of
the petiolar vascular axis is very clearly shown in the drawing by Mrs
Tansley reproduced in fig. 320. Protoxylem elements occur close to the
surface of each of the four arms of the xylem; the bays between the two
lateral and the two lower xylem groups contain large sieve-tubes. Portions
of the inner cortex are seen in places abutting on the small-celled pericyclic
tissue.
The right and left halves of the stele are not absolutely identical (fig. 320;
fig. 308, E); this is due to the fact that secondary branches are given off in
four rows, two alternately from the right and left sides. The preparation for
the departure of the lateral strands alters the configuration of the stelar
xylem groups. The protoxylem groups are not external but separated from
the surface by one or two layers of metaxylem. In fig. 308, E, the
occurrence of two protoxylem strands in the right-hand groups of
Page 511
metaxylem marks an early stage in the detachment of branches. These two
protoxylems are the result of division of single protoxylem strands like
those in the left-hand half of the stele. At a later stage the petiolar stele
assumes the form shown in fig. 308, F, and two small bundles are detached
to supply aphlebiae: this is followed by the stage shown in fig. G, where
two four-armed strands are passing out to a pair of branches of the leaf axis.
The separation of these two meristeles leaves the right-hand half of the stele
in the condition seen on the left-hand side of fig. E. The diagrammatic
sketch represented in fig. 310, C, shows one pair of branches in organic
connexion with the rachis, and each of these arms contains an obliquely cut
vascular strand like those in fig. 308, G.
The cortex consists for the most part of fairly thick-walled parenchyma
(fig. 321) which in the hypodermal region is replaced by a zone of thin-
walled lacunar tissue. A few stomata have been recognised in the
epidermis[1187]. The lower left-hand branch seen in fig. 310, C, has been
shaved by the cutting wheel so that the aerenchymatous tissue, l, is shown
in surface-view: a portion of this tissue is enlarged in fig. C′. The same
delicate chlorophyllous tissue forms a folded and shrivelled layer with an
uneven margin on the surface of the rachis and lateral branches. This hypha-
like tissue, which was discovered by Scott[1188] and figured by Bertrand[1189],
doubtless represents the much reduced lamina of the highly compound
leaves; it may be compared with the green outer cortex of Psilotum shoots
and with the lacunar tissue in the capsule of the common moss, Funaria
hygrometrica.
protoxylems are the result of division of single protoxylem strands like
those in the left-hand half of the stele. At a later stage the petiolar stele
assumes the form shown in fig. 308, F, and two small bundles are detached
to supply aphlebiae: this is followed by the stage shown in fig. G, where
two four-armed strands are passing out to a pair of branches of the leaf axis.
The separation of these two meristeles leaves the right-hand half of the stele
in the condition seen on the left-hand side of fig. E. The diagrammatic
sketch represented in fig. 310, C, shows one pair of branches in organic
connexion with the rachis, and each of these arms contains an obliquely cut
vascular strand like those in fig. 308, G.
The cortex consists for the most part of fairly thick-walled parenchyma
(fig. 321) which in the hypodermal region is replaced by a zone of thin-
walled lacunar tissue. A few stomata have been recognised in the
epidermis[1187]. The lower left-hand branch seen in fig. 310, C, has been
shaved by the cutting wheel so that the aerenchymatous tissue, l, is shown
in surface-view: a portion of this tissue is enlarged in fig. C′. The same
delicate chlorophyllous tissue forms a folded and shrivelled layer with an
uneven margin on the surface of the rachis and lateral branches. This hypha-
like tissue, which was discovered by Scott[1188] and figured by Bertrand[1189],
doubtless represents the much reduced lamina of the highly compound
leaves; it may be compared with the green outer cortex of Psilotum shoots
and with the lacunar tissue in the capsule of the common moss, Funaria
hygrometrica.
Page 512
Fig. 321. Stauropteris oldhamia: a, sections of pinnae. (× 10. From a section in the
Cambridge Botany School Coll.)
The rachis reproduced in fig. 321 is surrounded by an enormous number
of sections, some transverse, others more or less vertical, of branchlets of
various sizes. Fig. 310, B, shows the three-rayed vascular axis of a branch
of a lower order than those seen in fig. C, and the single vascular strands of
still finer ramifications of the leaf. The extraordinary abundance of axes of
different sizes, many of which are cut in the plane of branching, in close
association with the rachises of Stauropteris affords a striking
demonstration of the extent to which the subdivision of the frond was
carried in a small space. The leaves must have presented the appearance of
a feathery plexus of delicate green branchlets devoid of a lamina, some of
which bore terminal sporangia. It may be that the delicate fronds were
borne on a slender rhizome which lived epiphytically in a moist atmosphere
on the stouter stems of a supporting plant.
The sporangia[1190] of Stauropteris oldhamia are exannulate and nearly
spherical, with a wall of more than a single row of cells; they occur at the
tips of slender and doubtless pendulous branchlets. The discovery by
Scott[1191] of germinating spores (fig. 323) in a sporangium of this type
supplies an interesting piece of evidence in favour of the fern nature of
Cambridge Botany School Coll.)
The rachis reproduced in fig. 321 is surrounded by an enormous number
of sections, some transverse, others more or less vertical, of branchlets of
various sizes. Fig. 310, B, shows the three-rayed vascular axis of a branch
of a lower order than those seen in fig. C, and the single vascular strands of
still finer ramifications of the leaf. The extraordinary abundance of axes of
different sizes, many of which are cut in the plane of branching, in close
association with the rachises of Stauropteris affords a striking
demonstration of the extent to which the subdivision of the frond was
carried in a small space. The leaves must have presented the appearance of
a feathery plexus of delicate green branchlets devoid of a lamina, some of
which bore terminal sporangia. It may be that the delicate fronds were
borne on a slender rhizome which lived epiphytically in a moist atmosphere
on the stouter stems of a supporting plant.
The sporangia[1190] of Stauropteris oldhamia are exannulate and nearly
spherical, with a wall of more than a single row of cells; they occur at the
tips of slender and doubtless pendulous branchlets. The discovery by
Scott[1191] of germinating spores (fig. 323) in a sporangium of this type
supplies an interesting piece of evidence in favour of the fern nature of
Page 513
these reproductive organs. Similar germinating spores have been described
by Boodle[1192] in sporangia of Todea.
Fig. 322. Sporangia of Stauropteris oldhamia. St, stomium: p, palisade tissue. (From Tansley,
after D. H. Scott, from a drawing by Mrs D. H. Scott.)
Stauropteris burntislandica.
This Lower Carboniferous plant identified by Williamson with the
Oldham plant from the Lower Coal-Measures is referred by Bertrand to a
distinct species. In the structure of the rachis stele it agrees closely with
Stauropteris oldhamia; the main vascular strand gives off four rows of
branches, two from each side, and aphlebiae were present at the common
base of each pair of pinnae. Mrs Scott[1193], who has recently described the
sporangia of this species, speaks of one specimen in which germinating
spores were found. The same author gives an account of some curious
spindle-shaped bodies which she found in association with S.
burntislandica. The nature of these organs is uncertain; Mrs Scott inclines
by Boodle[1192] in sporangia of Todea.
Fig. 322. Sporangia of Stauropteris oldhamia. St, stomium: p, palisade tissue. (From Tansley,
after D. H. Scott, from a drawing by Mrs D. H. Scott.)
Stauropteris burntislandica.
This Lower Carboniferous plant identified by Williamson with the
Oldham plant from the Lower Coal-Measures is referred by Bertrand to a
distinct species. In the structure of the rachis stele it agrees closely with
Stauropteris oldhamia; the main vascular strand gives off four rows of
branches, two from each side, and aphlebiae were present at the common
base of each pair of pinnae. Mrs Scott[1193], who has recently described the
sporangia of this species, speaks of one specimen in which germinating
spores were found. The same author gives an account of some curious
spindle-shaped bodies which she found in association with S.
burntislandica. The nature of these organs is uncertain; Mrs Scott inclines
Page 514
to regard them as glands borne in pairs on lateral pedicels of the frond: she
adopts for these the name Bensonites fusiformis proposed by Dr Scott. If
there is a reasonable probability, as there certainly seems to be, in favour of
connecting these organs with Stauropteris, it is legitimate to question the
desirability of adding to the long list of names included in the group
Coenopterideae.
Fig. 323. Germinating spores from a sporangium of Stauropteris. (From Tansley, after D. H.
Scott.)
Corynepteris. Fig. 309, C, D.
This genus was founded by Baily[1194] on fragments of a fern from
Carboniferous rocks in County Limerick, Ireland, characterised by a
peculiar type of fructification which he named Corynepteris stellata. More
complete examples of the same genus have been described by Zeiller[1195]
from the Coal-field of Valenciennes. The sporangia are large, ovoid, and
sessile; the annulus (fig. 309, D) has the form of a complete vertical band
several cells in breadth: five to ten sporangia are grouped round a
receptacle. Zeiller describes two species as Sphenopteris (Corynepteris)
coralloides Gutb. and S. (Corynepteris) Essinghii And.; in both the fronds
are quadripinnate and bear aphlebiae at the base of the pinnae. The former
species is recorded by Kidston[1196] from the South Wales Coal-field. A
single pinnule of C. coralloides is shown in fig. 309, C. Potonié[1197] refers
this frond to his genus Alloiopteris: the portion of a pinna represented in fig.
adopts for these the name Bensonites fusiformis proposed by Dr Scott. If
there is a reasonable probability, as there certainly seems to be, in favour of
connecting these organs with Stauropteris, it is legitimate to question the
desirability of adding to the long list of names included in the group
Coenopterideae.
Fig. 323. Germinating spores from a sporangium of Stauropteris. (From Tansley, after D. H.
Scott.)
Corynepteris. Fig. 309, C, D.
This genus was founded by Baily[1194] on fragments of a fern from
Carboniferous rocks in County Limerick, Ireland, characterised by a
peculiar type of fructification which he named Corynepteris stellata. More
complete examples of the same genus have been described by Zeiller[1195]
from the Coal-field of Valenciennes. The sporangia are large, ovoid, and
sessile; the annulus (fig. 309, D) has the form of a complete vertical band
several cells in breadth: five to ten sporangia are grouped round a
receptacle. Zeiller describes two species as Sphenopteris (Corynepteris)
coralloides Gutb. and S. (Corynepteris) Essinghii And.; in both the fronds
are quadripinnate and bear aphlebiae at the base of the pinnae. The former
species is recorded by Kidston[1196] from the South Wales Coal-field. A
single pinnule of C. coralloides is shown in fig. 309, C. Potonié[1197] refers
this frond to his genus Alloiopteris: the portion of a pinna represented in fig.
Page 515
354, G shows the characteristic modified pinnule next the rachis. Zeiller
draws attention to the occurrence of two parallel lines on the rachis of a
specimen of Corynepteris coralloides which he figures[1198], and suggests
that these may indicate the existence of an H-shaped form of vascular
strand like that of Etapteris and Ankyropteris. The sorus of Corynepteris is
comparable with that of the Marattiaceae, but the broad annulus is a
difference which suggests affinity to Etapteris. The sorus is similar to that
in Diplolabis (fig. 309, A), but in that genus the sporangia are exannulate.
• • • • •
The vascular axis in the stems of different members of the
Coenopterideae assumes a variety of types. In Botryopteris antiqua the
xylem forms a solid protostele in which no protoxylem strands have been
recognised; in other species, e.g. B. ramosa, the cylindrical stele is similar
to that of Trichomanes radicans (Hymenophyllaceae) in the more or less
central position of the protoxylem. In Botryopteris forensis the protostele is
said to be exarch. The probability is that the central Botryopteris type is the
endarch protostele, a form of vascular axis which may be regarded as
primitive. The leaf-traces of the Lower Carboniferous Botryopteris antiqua
are simple oval strands differing but slightly from the cylindrical stele of the
stem. In the Upper Carboniferous British species the petiolar vascular
strand has become more specialised and farther removed from that of the
stem; in B. forensis the distinction between leaf and stem steles is still more
pronounced. It is perhaps legitimate to regard these types as representing an
ascending series, the more primitive of which are distinguished by the
greater similarity between leaf and stem, organs differentiated from a
primitive thallus[1199], that is from a vegetative body. Portions of this
ultimately became specialised as lateral members or leaves, while a portion
acquired the character of a radially constructed supporting axis or stem.
ANKYROPTERIS, ETC.
The vascular strand characteristic of the Zygoptereae is represented by
the H-shaped form as seen in Ankyropteris corrugata or in a more complex
form in A. bibractensis. This style of strand may be regarded as a
development from the simple strands of Grammatopteris and Tubicaulis or
Botryopteris antiqua along other lines than those followed by B. forensis.
The extension of the xylem in two symmetrically placed arms at the ends of
the cross-piece of the H is correlated with the habit of branching of the leaf-
draws attention to the occurrence of two parallel lines on the rachis of a
specimen of Corynepteris coralloides which he figures[1198], and suggests
that these may indicate the existence of an H-shaped form of vascular
strand like that of Etapteris and Ankyropteris. The sorus of Corynepteris is
comparable with that of the Marattiaceae, but the broad annulus is a
difference which suggests affinity to Etapteris. The sorus is similar to that
in Diplolabis (fig. 309, A), but in that genus the sporangia are exannulate.
• • • • •
The vascular axis in the stems of different members of the
Coenopterideae assumes a variety of types. In Botryopteris antiqua the
xylem forms a solid protostele in which no protoxylem strands have been
recognised; in other species, e.g. B. ramosa, the cylindrical stele is similar
to that of Trichomanes radicans (Hymenophyllaceae) in the more or less
central position of the protoxylem. In Botryopteris forensis the protostele is
said to be exarch. The probability is that the central Botryopteris type is the
endarch protostele, a form of vascular axis which may be regarded as
primitive. The leaf-traces of the Lower Carboniferous Botryopteris antiqua
are simple oval strands differing but slightly from the cylindrical stele of the
stem. In the Upper Carboniferous British species the petiolar vascular
strand has become more specialised and farther removed from that of the
stem; in B. forensis the distinction between leaf and stem steles is still more
pronounced. It is perhaps legitimate to regard these types as representing an
ascending series, the more primitive of which are distinguished by the
greater similarity between leaf and stem, organs differentiated from a
primitive thallus[1199], that is from a vegetative body. Portions of this
ultimately became specialised as lateral members or leaves, while a portion
acquired the character of a radially constructed supporting axis or stem.
ANKYROPTERIS, ETC.
The vascular strand characteristic of the Zygoptereae is represented by
the H-shaped form as seen in Ankyropteris corrugata or in a more complex
form in A. bibractensis. This style of strand may be regarded as a
development from the simple strands of Grammatopteris and Tubicaulis or
Botryopteris antiqua along other lines than those followed by B. forensis.
The extension of the xylem in two symmetrically placed arms at the ends of
the cross-piece of the H is correlated with the habit of branching of the leaf-
Page 516
system which forms one of the striking peculiarities of many of the
Zygoptereae. The solid type of stele characteristic of the Botryoptereae is
closely matched by that in the Lower Carboniferous stem discovered by Mr
Gordon[1200]. By the partial transformation of the central xylem region into
parenchymatous tissue and the concentration of water-conducting elements
in the peripheral region the style of Ankyropteris corrugata was developed.
The vascular strand of the older plant, which is of the Diplolabis type, may
be regarded as a more primitive style than that of the H-form of petiole
strand represented by Ankyropteris corrugata. A further stage in evolution
is seen in the stem stele of Ankyropteris Grayi and A. scandens, both of
which have the H-form of meristele. This step in increasing complexity of
stem stele, though probably connected with the increasing specialisation of
the leaf-traces, as held by Mr Tansley, may also be associated with the
development of a climbing habit. In Asterochlaena laxa Stenzel (fig. 324)
and A. ramosa (Cotta)[1201] the tendency towards a stellate expansion of the
originally cylindrical form of stele reaches a higher degree, with the result
that a style is evolved which agrees closely with that of the conducting
tissue of some existing Dicotyledonous Lianes.
Attention has already been drawn to the generalised features exhibited by
the Coenopterideae both in the anatomy of the steles and in the structure of
the sporangia. The conclusion arrived at is that while the Coenopterideae
foreshadow in some of their characters more than one group of more recent
ferns, some at least of their members afford convincing evidence of the
correctness of the view—which is also that of Dr Kidston and Mr Gwynne-
Vaughan—that the Osmundaceae and the Coenopterideae are offshoots of a
common stock.
Zygoptereae. The solid type of stele characteristic of the Botryoptereae is
closely matched by that in the Lower Carboniferous stem discovered by Mr
Gordon[1200]. By the partial transformation of the central xylem region into
parenchymatous tissue and the concentration of water-conducting elements
in the peripheral region the style of Ankyropteris corrugata was developed.
The vascular strand of the older plant, which is of the Diplolabis type, may
be regarded as a more primitive style than that of the H-form of petiole
strand represented by Ankyropteris corrugata. A further stage in evolution
is seen in the stem stele of Ankyropteris Grayi and A. scandens, both of
which have the H-form of meristele. This step in increasing complexity of
stem stele, though probably connected with the increasing specialisation of
the leaf-traces, as held by Mr Tansley, may also be associated with the
development of a climbing habit. In Asterochlaena laxa Stenzel (fig. 324)
and A. ramosa (Cotta)[1201] the tendency towards a stellate expansion of the
originally cylindrical form of stele reaches a higher degree, with the result
that a style is evolved which agrees closely with that of the conducting
tissue of some existing Dicotyledonous Lianes.
Attention has already been drawn to the generalised features exhibited by
the Coenopterideae both in the anatomy of the steles and in the structure of
the sporangia. The conclusion arrived at is that while the Coenopterideae
foreshadow in some of their characters more than one group of more recent
ferns, some at least of their members afford convincing evidence of the
correctness of the view—which is also that of Dr Kidston and Mr Gwynne-
Vaughan—that the Osmundaceae and the Coenopterideae are offshoots of a
common stock.
Page 517
Fig. 324. Asterochlaena laxa: part of stem with petiole and a few roots. From Tansley, after
Stenzel.
Stenzel.
Page 518
Page 519
CHAPTER XXVI.
I. Marsiliaceae.
HYDROPTERIDEAE
II. Salviniaceae.
The unsatisfactory and meagre records in regard to the past history of
these heterosporous Filicales render superfluous more than a brief reference
to the recent species.
Marsiliaceae.
This family is usually spoken of as including the two genera Marsilia and
Pilularia. Lindman[1202] has however founded a third genus, Regnellidium,
on a Brazilian plant which is distinguished by some well-defined characters
from all species of Marsilia. The members of the Marsiliaceae live for the
most part in swampy situations. Marsilia is represented in Europe by M.
quadrifoliata L. which occurs in Portugal, France, Germany and other parts
of the Continent, extending also to Kashmir, Northern China, and Japan. Of
the other 53 species, 17 are recorded from different regions in Africa, while
others occur in South America, Asia[1203], Australia, and elsewhere.
Pilularia globulifera L. is the only British representative of the
Hydropterideae. The remaining four species of the genus occur in South
America, California, New Zealand, Australia, and P. minuta Dur. is met
with in the South of France, Algeria, and Asia Minor in subtropical or warm
temperate regions.
The Marsiliaceae are regarded as more nearly related to the Schizaeaceae
than to any other family of homosporous ferns[1204]. Their heterospory, the
production of sporangia in closed fruit-like sporocarps, and the anatomical
features associated with existence in marshy habitats, tend to obscure the
resemblances to the true ferns.
• • • • •
I. Marsiliaceae.
HYDROPTERIDEAE
II. Salviniaceae.
The unsatisfactory and meagre records in regard to the past history of
these heterosporous Filicales render superfluous more than a brief reference
to the recent species.
Marsiliaceae.
This family is usually spoken of as including the two genera Marsilia and
Pilularia. Lindman[1202] has however founded a third genus, Regnellidium,
on a Brazilian plant which is distinguished by some well-defined characters
from all species of Marsilia. The members of the Marsiliaceae live for the
most part in swampy situations. Marsilia is represented in Europe by M.
quadrifoliata L. which occurs in Portugal, France, Germany and other parts
of the Continent, extending also to Kashmir, Northern China, and Japan. Of
the other 53 species, 17 are recorded from different regions in Africa, while
others occur in South America, Asia[1203], Australia, and elsewhere.
Pilularia globulifera L. is the only British representative of the
Hydropterideae. The remaining four species of the genus occur in South
America, California, New Zealand, Australia, and P. minuta Dur. is met
with in the South of France, Algeria, and Asia Minor in subtropical or warm
temperate regions.
The Marsiliaceae are regarded as more nearly related to the Schizaeaceae
than to any other family of homosporous ferns[1204]. Their heterospory, the
production of sporangia in closed fruit-like sporocarps, and the anatomical
features associated with existence in marshy habitats, tend to obscure the
resemblances to the true ferns.
• • • • •
Page 520
The genus Marsilidium proposed by Schenk[1205] for a piece of an axis,
bearing apparently a whorl of six leaflets, from the Wealden of Osterwald,
cannot be regarded as satisfactory evidence of the existence of the
Marsiliaceae in the Wealden flora of North Germany.
The six leaflets of Marsilidium speciosum, having a length of 5 cm., are
similar in shape to the four leaflets of recent species of Marsilia, but they
differ in the repeated dichotomy of the veins from the reticulate venation of
the recent forms. It is worthy of note, however, that in Lindman’s Brazilian
type Regnellidium diphyllum (fig. 326, A), the leaflets are characterised by
dichotomous and not by anastomosing veins.
Hollick[1206] has described some impressions of imperfect orbicular leaves
with a “finely flabellate obscurely reticulated(?) venation” from Cretaceous
rocks of Long Island as Marsilia Andersoni, but these are too fragmentary
to be accorded this generic designation. My friend Dr Krasser informs me
that he is describing some well-preserved leaves from Cretaceous beds of
Grünbach in Lower Austria as Marsilia Nathorsti[1207]. He compares these
with the recent form Marsilia elata, a variety of M. Drummondi.
Another Lower Cretaceous species Marsilia perucensis has been figured
by Frič and Bayer[1208] as a stalked fruit-like body from Bohemia. This was
originally described by Velenovský as M. cretacea, but under this name
Heer[1209] had previously recorded a supposed sporocarp from Greenland.
These fossils have little claim to recognition as examples of Marsiliaceous
plants.
The fragment figured by Heer[1210] from Tertiary rocks of Oeningen as
Pilularia pedunculata is too small to determine with reasonable accuracy.
Other supposed representatives of the family mentioned in palaeobotanical
literature are not of sufficient importance to describe.
Salviniaceae.
The two genera of Salviniaceae, Salvinia and Azolla, are water plants,
and are usually described as annuals which survive the less favourable
season in the form of detached sporocarps. Goebel[1211] states that all the
tropical species of Salvinia known to him have an unlimited existence.
bearing apparently a whorl of six leaflets, from the Wealden of Osterwald,
cannot be regarded as satisfactory evidence of the existence of the
Marsiliaceae in the Wealden flora of North Germany.
The six leaflets of Marsilidium speciosum, having a length of 5 cm., are
similar in shape to the four leaflets of recent species of Marsilia, but they
differ in the repeated dichotomy of the veins from the reticulate venation of
the recent forms. It is worthy of note, however, that in Lindman’s Brazilian
type Regnellidium diphyllum (fig. 326, A), the leaflets are characterised by
dichotomous and not by anastomosing veins.
Hollick[1206] has described some impressions of imperfect orbicular leaves
with a “finely flabellate obscurely reticulated(?) venation” from Cretaceous
rocks of Long Island as Marsilia Andersoni, but these are too fragmentary
to be accorded this generic designation. My friend Dr Krasser informs me
that he is describing some well-preserved leaves from Cretaceous beds of
Grünbach in Lower Austria as Marsilia Nathorsti[1207]. He compares these
with the recent form Marsilia elata, a variety of M. Drummondi.
Another Lower Cretaceous species Marsilia perucensis has been figured
by Frič and Bayer[1208] as a stalked fruit-like body from Bohemia. This was
originally described by Velenovský as M. cretacea, but under this name
Heer[1209] had previously recorded a supposed sporocarp from Greenland.
These fossils have little claim to recognition as examples of Marsiliaceous
plants.
The fragment figured by Heer[1210] from Tertiary rocks of Oeningen as
Pilularia pedunculata is too small to determine with reasonable accuracy.
Other supposed representatives of the family mentioned in palaeobotanical
literature are not of sufficient importance to describe.
Salviniaceae.
The two genera of Salviniaceae, Salvinia and Azolla, are water plants,
and are usually described as annuals which survive the less favourable
season in the form of detached sporocarps. Goebel[1211] states that all the
tropical species of Salvinia known to him have an unlimited existence.
Page 521
Salvinia natans, Hoffm., the only European species, extends from the
South of France to Northern China and the plains of India: the other twelve
species are mostly tropical. Azolla, represented by four species, occurs in
Western and Southern North America, South America, Madagascar,
Australia, New Zealand, and is widely spread in tropical Asia and Africa.
Species of Azolla frequently form a considerable proportion of the
floating carpet of vegetation on inland waters[1212] growing under conditions
which might be supposed favourable for preservation in a fossil state.
The Salviniaceae, though probably rather farther removed than the
Marsiliaceae from the homosporous Filicineae, are considered by
Bower[1213] to be related to the Gradatae, but modified in consequence of
their aquatic habit and the assumption of heterospory.
No undoubted examples of fossil species of Azolla have been described.
Salvinia, on the other hand, is represented by several Tertiary species, for
the most part founded on leaves only, and Hollick[1214], who published a list
of fossil Salvinias, has described detached leaves as Salvinia elliptica
Newb. from what may be Upper Cretaceous rocks from Carbonado,
Washington. Some of the leaves figured as Tertiary Salvinias are of no
value as evidence of the former distribution of the genus[1215].
From the Coal-beds of Yen-Bäi (Tonkin), probably of Miocene age,
Zeiller[1216] has figured some well-preserved impressions of oval or orbicular
leaves, 15 mm. long and 10–20 mm. broad, characterised by reticulate
venation and by cordate bases, which he refers to Heer’s Swiss species
Salvinia formosa[1217].
Dr Zeiller[1218] in the most recently published part of his series of valuable
résumés of palaeobotanical literature refers to a description by Brabenec of
specimens of this species from Bohemian Tertiary beds showing both
microspores and megaspores.
One of the most complete specimens so far discovered has recently been
described by Fritel[1219] from Eocene beds of the Paris Basin as Salvinia
Zeilleri. This species, founded on portions of stems bearing floating leaves,
submerged root-like leaves, and sporocarps, is compared with a recent
tropical American species S. auriculata.
South of France to Northern China and the plains of India: the other twelve
species are mostly tropical. Azolla, represented by four species, occurs in
Western and Southern North America, South America, Madagascar,
Australia, New Zealand, and is widely spread in tropical Asia and Africa.
Species of Azolla frequently form a considerable proportion of the
floating carpet of vegetation on inland waters[1212] growing under conditions
which might be supposed favourable for preservation in a fossil state.
The Salviniaceae, though probably rather farther removed than the
Marsiliaceae from the homosporous Filicineae, are considered by
Bower[1213] to be related to the Gradatae, but modified in consequence of
their aquatic habit and the assumption of heterospory.
No undoubted examples of fossil species of Azolla have been described.
Salvinia, on the other hand, is represented by several Tertiary species, for
the most part founded on leaves only, and Hollick[1214], who published a list
of fossil Salvinias, has described detached leaves as Salvinia elliptica
Newb. from what may be Upper Cretaceous rocks from Carbonado,
Washington. Some of the leaves figured as Tertiary Salvinias are of no
value as evidence of the former distribution of the genus[1215].
From the Coal-beds of Yen-Bäi (Tonkin), probably of Miocene age,
Zeiller[1216] has figured some well-preserved impressions of oval or orbicular
leaves, 15 mm. long and 10–20 mm. broad, characterised by reticulate
venation and by cordate bases, which he refers to Heer’s Swiss species
Salvinia formosa[1217].
Dr Zeiller[1218] in the most recently published part of his series of valuable
résumés of palaeobotanical literature refers to a description by Brabenec of
specimens of this species from Bohemian Tertiary beds showing both
microspores and megaspores.
One of the most complete specimens so far discovered has recently been
described by Fritel[1219] from Eocene beds of the Paris Basin as Salvinia
Zeilleri. This species, founded on portions of stems bearing floating leaves,
submerged root-like leaves, and sporocarps, is compared with a recent
tropical American species S. auriculata.
Page 522
It is noteworthy that no authentic records of Hydropterideae have been
discovered in Palaeozoic rocks[1220]. Comparisons have been made in the
case of the genera Traquairia Carr. and Sporocarpon Will. with the
reproductive organs of Azolla[1221], but these rest on a wholly insufficient
basis.
Dawson[1222] proposed the generic name Protosalvinia for some spores of
Devonian age, which he regarded on inadequate grounds as evidence of
Palaeozoic Hydropterideae.
Zeiller[1223], in discussing the possible relationships of the problematical
type Chorionopteris gleichenioides Cord., suggests a possible alliance with
the Hydropterideae. Corda founded the genus Chorionopteris[1224] on some
small fragments of pinnules, 6–7 mm. long, found in the Carboniferous
rocks of Radnitz in Bohemia.
The lobes of the pinnules are incurved distally to form a capsule,
containing four sporangia, which apparently opened on dehiscence into four
valves; the spores are of one size. The material is however insufficient for
accurate determination.
There is no evidence contributed by fossil records which indicates a high
antiquity for the Hydropterideae. It is unsafe to base any conclusion on the
absence of undoubted Palaeozoic representatives of this group; but the
almost complete absence of records in pre-Tertiary strata is a fact which
may be allowed some weight in regard to the possible evolution of the
heterosporous filicales at a comparatively late period in the earth’s history.
A description of the Mesozoic genus Sagenopteris may be conveniently
included in this chapter, though as in many other instances the inclusion of
a genus under the heading of a recent family name does not by any means
imply that the position of the extinct type is regarded as settled.
Sagenopteris.
This generic name was applied by Presl[1225] to small fronds composed of
four or rarely two palmately disposed leaflets with a more or less distinct
midrib and anastomosing secondary veins. Schimper[1226] compared
Sagenopteris with Marsilia, but did not regard the resemblance as evidence
of relationship. Nathorst[1227] expressed the opinion that certain fruit-like
discovered in Palaeozoic rocks[1220]. Comparisons have been made in the
case of the genera Traquairia Carr. and Sporocarpon Will. with the
reproductive organs of Azolla[1221], but these rest on a wholly insufficient
basis.
Dawson[1222] proposed the generic name Protosalvinia for some spores of
Devonian age, which he regarded on inadequate grounds as evidence of
Palaeozoic Hydropterideae.
Zeiller[1223], in discussing the possible relationships of the problematical
type Chorionopteris gleichenioides Cord., suggests a possible alliance with
the Hydropterideae. Corda founded the genus Chorionopteris[1224] on some
small fragments of pinnules, 6–7 mm. long, found in the Carboniferous
rocks of Radnitz in Bohemia.
The lobes of the pinnules are incurved distally to form a capsule,
containing four sporangia, which apparently opened on dehiscence into four
valves; the spores are of one size. The material is however insufficient for
accurate determination.
There is no evidence contributed by fossil records which indicates a high
antiquity for the Hydropterideae. It is unsafe to base any conclusion on the
absence of undoubted Palaeozoic representatives of this group; but the
almost complete absence of records in pre-Tertiary strata is a fact which
may be allowed some weight in regard to the possible evolution of the
heterosporous filicales at a comparatively late period in the earth’s history.
A description of the Mesozoic genus Sagenopteris may be conveniently
included in this chapter, though as in many other instances the inclusion of
a genus under the heading of a recent family name does not by any means
imply that the position of the extinct type is regarded as settled.
Sagenopteris.
This generic name was applied by Presl[1225] to small fronds composed of
four or rarely two palmately disposed leaflets with a more or less distinct
midrib and anastomosing secondary veins. Schimper[1226] compared
Sagenopteris with Marsilia, but did not regard the resemblance as evidence
of relationship. Nathorst[1227] expressed the opinion that certain fruit-like
Page 523
bodies obtained from the Rhaetic beds of Scania are of the nature of
sporocarps and were borne by Sagenopteris, with the leaves of which they
were associated. He published a drawing of part of a fruit showing on its
partially flattened surface some raised oval bodies which are considered to
be spores. Dr Nathorst kindly placed at my disposal the drawings
reproduced in fig. 325 made from some of his specimens found at Bjuf in
Scania.
In contour and superficial features, e.g. the veining on the wall, these
bodies bear a fairly close resemblance to the sporocarps of recent species of
Marsilia. They were found in association with the leaves of Sagenopteris
undulata Nath., an abundant Scania type similar in form to the English
Jurassic species S. Phillipsi (figs. 327, 328). Heer was independently led by
an examination of some examples of the Swedish “fruits” to compare them
with the sporocarps of Marsilia. A small spherical body is figured by
Zigno[1228] close to a leaf of his species S. angustifolia, which may be a
sporocarp. In a recent paper, Salfeld[1229] says that he found fructification on
the lower face of the leaflets of S. Nilssoniana Brongn. from German
Jurassic rocks, but he brings forward no evidence in support of this
statement. The systematic position of Sagenopteris is by no means settled.
In a previous account of the genus I expressed the view that it is probably a
member of the true ferns[1230], but the resemblance of Dr Nathorst’s
drawings to the Marsilian sporocarps influences me in favour of his opinion
that Sagenopteris may belong to the Hydropterideae. The evidence, as
Solms-Laubach[1231] states, is not wholly satisfactory: Schenk points out that
the frequent occurrence of detached Sagenopteris leaflets suggests that they
easily fell off the petiole, whereas in Marsilia the leaflets do not fall off
independently. The discovery of a new type of Marsiliaceae in Brazil,
which Lindman has described as Regnellidium diphyllum[1232] (fig. 326, A),
affords an additional piece of evidence bearing on the comparison of
Sagenopteris with members of this family. In Regnellidium the leaves differ
from those of Marsilia in bearing two instead of four leaflets, and in the
former the veins are repeatedly forked, and do not anastomose as in
Marsilia. In the possession of only two leaflets Regnellidium agrees with
some forms of Sagenopteris (fig. 328).
sporocarps and were borne by Sagenopteris, with the leaves of which they
were associated. He published a drawing of part of a fruit showing on its
partially flattened surface some raised oval bodies which are considered to
be spores. Dr Nathorst kindly placed at my disposal the drawings
reproduced in fig. 325 made from some of his specimens found at Bjuf in
Scania.
In contour and superficial features, e.g. the veining on the wall, these
bodies bear a fairly close resemblance to the sporocarps of recent species of
Marsilia. They were found in association with the leaves of Sagenopteris
undulata Nath., an abundant Scania type similar in form to the English
Jurassic species S. Phillipsi (figs. 327, 328). Heer was independently led by
an examination of some examples of the Swedish “fruits” to compare them
with the sporocarps of Marsilia. A small spherical body is figured by
Zigno[1228] close to a leaf of his species S. angustifolia, which may be a
sporocarp. In a recent paper, Salfeld[1229] says that he found fructification on
the lower face of the leaflets of S. Nilssoniana Brongn. from German
Jurassic rocks, but he brings forward no evidence in support of this
statement. The systematic position of Sagenopteris is by no means settled.
In a previous account of the genus I expressed the view that it is probably a
member of the true ferns[1230], but the resemblance of Dr Nathorst’s
drawings to the Marsilian sporocarps influences me in favour of his opinion
that Sagenopteris may belong to the Hydropterideae. The evidence, as
Solms-Laubach[1231] states, is not wholly satisfactory: Schenk points out that
the frequent occurrence of detached Sagenopteris leaflets suggests that they
easily fell off the petiole, whereas in Marsilia the leaflets do not fall off
independently. The discovery of a new type of Marsiliaceae in Brazil,
which Lindman has described as Regnellidium diphyllum[1232] (fig. 326, A),
affords an additional piece of evidence bearing on the comparison of
Sagenopteris with members of this family. In Regnellidium the leaves differ
from those of Marsilia in bearing two instead of four leaflets, and in the
former the veins are repeatedly forked, and do not anastomose as in
Marsilia. In the possession of only two leaflets Regnellidium agrees with
some forms of Sagenopteris (fig. 328).
Page 524
Fig. 325. Sporocarp-like bodies found in association with the leaves of Sagenopteris. (Nat.
size. From drawings supplied by Dr Nathorst.)
Fig. 326.
A. Regnellidium diphyllum Lind. Single leaf and stalked sporocarp. (⅞ nat. size. After
Lindman.)
B. Cuticle of Sagenopteris rhoifolia. (After Schenk.)
Sagenopteris Phillipsi (Brongniart)[1233]. Figs. 327, 328.
size. From drawings supplied by Dr Nathorst.)
Fig. 326.
A. Regnellidium diphyllum Lind. Single leaf and stalked sporocarp. (⅞ nat. size. After
Lindman.)
B. Cuticle of Sagenopteris rhoifolia. (After Schenk.)
Sagenopteris Phillipsi (Brongniart)[1233]. Figs. 327, 328.
Page 525
1828. Glossopteris Phillipsi, Brongniart, Hist. vég. foss. p. 225, Pls. lxi.
bis, lxiii.
1838. Sagenopteris Phillipsi, Presl, in Sternberg’s Flor. Vorwelt, vii. p. 69.
Fig. 327. Sagenopteris Phillipsi.
A. From the type-specimens of Lindley and Hutton (Glossopteris Phillipsi).
Gristhorpe Bay, Yorkshire. British Museum, No. 39221. Slightly reduced. M.S.
B. From a specimen in the British Museum (39222). Nat. size. Figured by Lindley
and Hutton as Glossopteris Phillipsi.
The fronds of this common Jurassic species, which is recorded from
many European localities, from North America, Australia, the Antarctic
bis, lxiii.
1838. Sagenopteris Phillipsi, Presl, in Sternberg’s Flor. Vorwelt, vii. p. 69.
Fig. 327. Sagenopteris Phillipsi.
A. From the type-specimens of Lindley and Hutton (Glossopteris Phillipsi).
Gristhorpe Bay, Yorkshire. British Museum, No. 39221. Slightly reduced. M.S.
B. From a specimen in the British Museum (39222). Nat. size. Figured by Lindley
and Hutton as Glossopteris Phillipsi.
The fronds of this common Jurassic species, which is recorded from
many European localities, from North America, Australia, the Antarctic
Page 526
regions[1234], and elsewhere, are very variable as regards the form, size, and
number of the leaflets.
Frond petiolate, in some forms the petiole bears four linear or oval-lanceolate leaflets having a
distinct midrib and oblique anastomosing veins. In others a shorter winged petiole bears one or
two shorter and broader, somewhat obcuneate, leaflets without a midrib.
It is probable that Bunbury[1235] was correct in his opinion that the
specimen figured by Lindley and Hutton[1236] as Otopteris cuneata,
characterised by two leaflets (fig. 328), is not specifically distinct from the
normal form with four leaflets (fig. 327).
Similarly, such specimens as that represented in Pl. xviii., fig. 3 of the
first part of my Jurassic Flora, in which a short stalk bears only one leaflet
may, provisionally at least, be included in Brongniart’s species. Yabe[1237]
describes a form with two leaflets from Jurassic rocks of Korea as
Sagenopteris bilobata which resembles S. Phillipsi; and Moeller[1238] records
a specimen similar to that represented in fig. 328 from Bornholm as S.
cuneata (Lind. and Hutt.).
Fig. 328. Sagenopteris Phillipsi. From a specimen in the Manchester University Museum.
Nat. size.
The leaf shown in fig. 327, A, in which the longest segments are 4·5 cm.
in length, represents the most abundant form and illustrates the very close
agreement between S. Phillipsi and the Rhaetic species S. rhoifolia. Fig.
327, B, which is drawn from a specimen figured by Lindley and Hutton[1239],
shows a leaf with longer (6·5 cm.) and much narrower segments. Broader
leaflets are occasionally met with in which the lamina reaches a length of 11
cm.[1240]
Leaves with leaflets narrower (3 mm. broad) than those represented in
fig. 327, B, are described by Zigno[1241] from Jurassic beds of Italy as S.
angustifolia and by Moeller[1242] from the Jurassic of Bornholm as S.
number of the leaflets.
Frond petiolate, in some forms the petiole bears four linear or oval-lanceolate leaflets having a
distinct midrib and oblique anastomosing veins. In others a shorter winged petiole bears one or
two shorter and broader, somewhat obcuneate, leaflets without a midrib.
It is probable that Bunbury[1235] was correct in his opinion that the
specimen figured by Lindley and Hutton[1236] as Otopteris cuneata,
characterised by two leaflets (fig. 328), is not specifically distinct from the
normal form with four leaflets (fig. 327).
Similarly, such specimens as that represented in Pl. xviii., fig. 3 of the
first part of my Jurassic Flora, in which a short stalk bears only one leaflet
may, provisionally at least, be included in Brongniart’s species. Yabe[1237]
describes a form with two leaflets from Jurassic rocks of Korea as
Sagenopteris bilobata which resembles S. Phillipsi; and Moeller[1238] records
a specimen similar to that represented in fig. 328 from Bornholm as S.
cuneata (Lind. and Hutt.).
Fig. 328. Sagenopteris Phillipsi. From a specimen in the Manchester University Museum.
Nat. size.
The leaf shown in fig. 327, A, in which the longest segments are 4·5 cm.
in length, represents the most abundant form and illustrates the very close
agreement between S. Phillipsi and the Rhaetic species S. rhoifolia. Fig.
327, B, which is drawn from a specimen figured by Lindley and Hutton[1239],
shows a leaf with longer (6·5 cm.) and much narrower segments. Broader
leaflets are occasionally met with in which the lamina reaches a length of 11
cm.[1240]
Leaves with leaflets narrower (3 mm. broad) than those represented in
fig. 327, B, are described by Zigno[1241] from Jurassic beds of Italy as S.
angustifolia and by Moeller[1242] from the Jurassic of Bornholm as S.
Page 527
Phillipsi f. pusilla. A coarser type of venation than that of S. Phillipsi is
occasionally found in Jurassic examples, as in S. grandifolia Font.[1243] from
Oregon and S. Nathorsti Barth. from Bornholm[1244].
• • • • •
Sagenopteris is recorded also from several Rhaetic floras. The best
known species, S. rhoifolia Presl[1245], is hardly distinguishable from some
forms of S. Phillipsi or from the Italian Jurassic species described by Zigno
as S. Goeppertiana[1246], though the leaflets are usually rather larger. This
species was first described by Brongniart as Filicites Nilssoniana[1247], and a
few authors[1248] have adopted this specific name because of its priority over
Presl’s designation. As Nathorst remarks, to give up the well-known name
S. rhoifolia for S. Nilssoniana is “mere pedantry.” The epidermis of S.
rhoifolia as figured by Schenk[1249] consists of cells with straight and not
undulating walls: stomata occur on the lower surface (fig. 326, B).
Rhaetic leaves of the type represented by S. rhoifolia have a wide
geographical distribution.
The specimens described by Feistmantel from the Damuda series of India
as Sagenopteris longifolia are no doubt fronds of Glossopteris
longifolia[1250].
The Wealden species Sagenopteris Mantelli (Dunk.)[1251] agrees closely in
habit and in the form of the leaflets with S. Phillipsi and S. rhoifolia. It is
probable that some of the leaves described by Velenovský[1252] from Lower
Cretaceous rocks in Bohemia as Thinnfeldia variabilis are portions of
Sagenopteris fronds. S. Mantelli is recorded from several European
localities, from California[1253], and elsewhere.
Sagenopteris appears to have been widely distributed during the Rhaetic,
Jurassic and Lower Cretaceous floras. The very great similarity between the
specimens recorded from these three formations renders the genus an
uncertain guide in regard to geological age. Decisive evidence as to its
position in the plant kingdom is at present lacking: the inclusion of the
genus as a possible member of the Hydropterideae has still to be justified.
occasionally found in Jurassic examples, as in S. grandifolia Font.[1243] from
Oregon and S. Nathorsti Barth. from Bornholm[1244].
• • • • •
Sagenopteris is recorded also from several Rhaetic floras. The best
known species, S. rhoifolia Presl[1245], is hardly distinguishable from some
forms of S. Phillipsi or from the Italian Jurassic species described by Zigno
as S. Goeppertiana[1246], though the leaflets are usually rather larger. This
species was first described by Brongniart as Filicites Nilssoniana[1247], and a
few authors[1248] have adopted this specific name because of its priority over
Presl’s designation. As Nathorst remarks, to give up the well-known name
S. rhoifolia for S. Nilssoniana is “mere pedantry.” The epidermis of S.
rhoifolia as figured by Schenk[1249] consists of cells with straight and not
undulating walls: stomata occur on the lower surface (fig. 326, B).
Rhaetic leaves of the type represented by S. rhoifolia have a wide
geographical distribution.
The specimens described by Feistmantel from the Damuda series of India
as Sagenopteris longifolia are no doubt fronds of Glossopteris
longifolia[1250].
The Wealden species Sagenopteris Mantelli (Dunk.)[1251] agrees closely in
habit and in the form of the leaflets with S. Phillipsi and S. rhoifolia. It is
probable that some of the leaves described by Velenovský[1252] from Lower
Cretaceous rocks in Bohemia as Thinnfeldia variabilis are portions of
Sagenopteris fronds. S. Mantelli is recorded from several European
localities, from California[1253], and elsewhere.
Sagenopteris appears to have been widely distributed during the Rhaetic,
Jurassic and Lower Cretaceous floras. The very great similarity between the
specimens recorded from these three formations renders the genus an
uncertain guide in regard to geological age. Decisive evidence as to its
position in the plant kingdom is at present lacking: the inclusion of the
genus as a possible member of the Hydropterideae has still to be justified.
Page 528
Page 529
CHAPTER XXVII.
GENERA OF PTERIDOSPERMS, FERNS, AND PLANTAE
INCERTAE SEDIS.
The genera and species described in this Chapter are founded on sterile
leaves or portions of leaves, and in the great majority of cases the
reproductive organs are either imperfectly known or have still to be
discovered. Some of the genera, the smaller number, are no doubt true
ferns, while most of them may safely be regarded as plants which will
ultimately be shown to belong to some other group, in most cases that of the
Pteridosperms. It is possible that a few of the types may be members of the
Cycadophyta rather than of the Pteridospermeae, but evidence as to
systematic position is for the most part of a negative kind or too incomplete
to lead to any definite expression of opinion as to the cycadean or
pteridosperm nature of the imperfectly known Palaeozoic or Mesozoic
species. Many of the genera are of little botanical interest, though even the
most problematical are of importance as criteria of geological age. Genera
which there is good reason for including in the Pteridosperms are dealt with
in this section, in order that the Chapter in Volume iii. devoted to this
important group may be limited to more completely known types.
In most text-books it is customary to employ family names for sterile
fern-like fronds which possess similar venation features or have in common
certain vegetative characters, the value of which it is impossible to estimate.
In the following account family or group names are not adopted, on the
ground that such slight utility as they may have is more than
counterbalanced by the risk attending a grouping under one name of plants
which may agree only in unessential characters. The practice of classifying
fossil plants has been carried to excess. Grouping together genera as a
GENERA OF PTERIDOSPERMS, FERNS, AND PLANTAE
INCERTAE SEDIS.
The genera and species described in this Chapter are founded on sterile
leaves or portions of leaves, and in the great majority of cases the
reproductive organs are either imperfectly known or have still to be
discovered. Some of the genera, the smaller number, are no doubt true
ferns, while most of them may safely be regarded as plants which will
ultimately be shown to belong to some other group, in most cases that of the
Pteridosperms. It is possible that a few of the types may be members of the
Cycadophyta rather than of the Pteridospermeae, but evidence as to
systematic position is for the most part of a negative kind or too incomplete
to lead to any definite expression of opinion as to the cycadean or
pteridosperm nature of the imperfectly known Palaeozoic or Mesozoic
species. Many of the genera are of little botanical interest, though even the
most problematical are of importance as criteria of geological age. Genera
which there is good reason for including in the Pteridosperms are dealt with
in this section, in order that the Chapter in Volume iii. devoted to this
important group may be limited to more completely known types.
In most text-books it is customary to employ family names for sterile
fern-like fronds which possess similar venation features or have in common
certain vegetative characters, the value of which it is impossible to estimate.
In the following account family or group names are not adopted, on the
ground that such slight utility as they may have is more than
counterbalanced by the risk attending a grouping under one name of plants
which may agree only in unessential characters. The practice of classifying
fossil plants has been carried to excess. Grouping together genera as a
Page 530
matter of convenience unavoidably creates a prejudice in favour of actual
relationship, which may or may not exist.
Taeniopteris.
This generic name was instituted by Brongniart[1254] for simple linear or
broadly linear leaves with a prominent midrib from which secondary veins,
simple or dichotomously branched, are given off at right angles or
obliquely. The frond of the type-species Taeniopteris vittata (fig. 332),
characteristic of Jurassic floras, was compared by Brongniart with the
pinnules of Danaea and Angiopteris. Among recent ferns the Taeniopteris
form of frond and venation is represented by Oleandra neriiformis,
Asplenium nidus, and many other species. Though usually applied to fronds
which there is good reason for regarding as simple leaves, the generic
designation Taeniopteris has been extended to include pinnate fronds, e.g.
the Upper Palaeozoic species T. jejunata Grand’Eury, and T. Carnoti Ren.
and Zeill. (fig. 330, A). The compound fronds from the Lower Coal-
Measures of Missouri described by Dr White[1255] as T. missouriensis are
characterised by decurrent and confluent Taeniopteroid pinnules. In a later
reference[1256] to this plant White pertinently adds, “perhaps it belongs more
properly in Alethopteris.”
Leaves of the Taeniopteris type are described by several authors as
species of Oleandridium, Angiopteridium, Danaeites, Marattia, and other
genera. In such species of Taeniopteroid leaves as have been dealt with in a
former Chapter, the occurrence of sori justifies the substitution of a name
denoting a close relationship to existing members of the Marattiaceae, but
in the absence of fertile specimens the provisional designation Taeniopteris
should be retained. It is often difficult to decide between Taeniopteris and
Nilssonia as the more suitable name to apply to fragments of fossil leaves of
Mesozoic age. Taeniopteris is, however, distinguished from the Cycadean
genus by the greater prominence of the rachis, also by the dichotomous
branching of the secondary veins, usually close to their origin and at
varying distances between the axis of the frond and the edge of the lamina.
The genus Taeniopteris, though most abundant in Rhaetic and Jurassic
strata, occurs also in Upper Carboniferous and Lower Permian rocks. The
generic name Macrotaeniopteris instituted by Schimper[1257] has been used
relationship, which may or may not exist.
Taeniopteris.
This generic name was instituted by Brongniart[1254] for simple linear or
broadly linear leaves with a prominent midrib from which secondary veins,
simple or dichotomously branched, are given off at right angles or
obliquely. The frond of the type-species Taeniopteris vittata (fig. 332),
characteristic of Jurassic floras, was compared by Brongniart with the
pinnules of Danaea and Angiopteris. Among recent ferns the Taeniopteris
form of frond and venation is represented by Oleandra neriiformis,
Asplenium nidus, and many other species. Though usually applied to fronds
which there is good reason for regarding as simple leaves, the generic
designation Taeniopteris has been extended to include pinnate fronds, e.g.
the Upper Palaeozoic species T. jejunata Grand’Eury, and T. Carnoti Ren.
and Zeill. (fig. 330, A). The compound fronds from the Lower Coal-
Measures of Missouri described by Dr White[1255] as T. missouriensis are
characterised by decurrent and confluent Taeniopteroid pinnules. In a later
reference[1256] to this plant White pertinently adds, “perhaps it belongs more
properly in Alethopteris.”
Leaves of the Taeniopteris type are described by several authors as
species of Oleandridium, Angiopteridium, Danaeites, Marattia, and other
genera. In such species of Taeniopteroid leaves as have been dealt with in a
former Chapter, the occurrence of sori justifies the substitution of a name
denoting a close relationship to existing members of the Marattiaceae, but
in the absence of fertile specimens the provisional designation Taeniopteris
should be retained. It is often difficult to decide between Taeniopteris and
Nilssonia as the more suitable name to apply to fragments of fossil leaves of
Mesozoic age. Taeniopteris is, however, distinguished from the Cycadean
genus by the greater prominence of the rachis, also by the dichotomous
branching of the secondary veins, usually close to their origin and at
varying distances between the axis of the frond and the edge of the lamina.
The genus Taeniopteris, though most abundant in Rhaetic and Jurassic
strata, occurs also in Upper Carboniferous and Lower Permian rocks. The
generic name Macrotaeniopteris instituted by Schimper[1257] has been used
Page 531
for leaves differing only in size from the usual type of Taeniopteris, but
there is no adequate reason for its retention.
The species included in Taeniopteris afford no satisfactory evidence as to
their systematic position. It is obviously unwise to adopt such generic titles
as Oleandridium, Marattiopsis, etc., merely because of resemblance in the
venation of sterile fragments to Oleandra or Marattiaceous ferns.
Some specimens of Taeniopteris fronds described by Mr Sellards[1258]
from Permian rocks of Kansas, which are referred to later, have furnished
unconvincing evidence of reproductive organs.
Taeniopteris multinervis, Weiss. Fig. 329, A, B.
The late Dr Weiss[1259] instituted this species (which he designated
Taeniopteris multinervia, though the specific name multinervis is constantly
used) for a fragment of a leaf from the Lower Permian of Lebach
characterised by numerous forked veins given off at right angles from a
prominent rachis (fig. 329, B). This type of frond is recorded from the
Permian of Trienbach (Alsace) by Zeiller[1260], by Renault[1261] and
Zeiller[1262] from the Upper Carboniferous of Autun, and from other
localities. The lamina of the simple leaf reaches a breadth of 6 cm. and a
length of 40 cm. (fig. 329, A); the numerous secondary veins (25–36 per
cm. of lamina) are either at right angles to the rachis or given off at an acute
angle. The mesophyll consists of polygonal cells some of which are
elongated at right angles to the surface of the lamina. A very similar form is
described by Fontaine and White from the Permian of Virginia as T.
Lescuriana[1263].
there is no adequate reason for its retention.
The species included in Taeniopteris afford no satisfactory evidence as to
their systematic position. It is obviously unwise to adopt such generic titles
as Oleandridium, Marattiopsis, etc., merely because of resemblance in the
venation of sterile fragments to Oleandra or Marattiaceous ferns.
Some specimens of Taeniopteris fronds described by Mr Sellards[1258]
from Permian rocks of Kansas, which are referred to later, have furnished
unconvincing evidence of reproductive organs.
Taeniopteris multinervis, Weiss. Fig. 329, A, B.
The late Dr Weiss[1259] instituted this species (which he designated
Taeniopteris multinervia, though the specific name multinervis is constantly
used) for a fragment of a leaf from the Lower Permian of Lebach
characterised by numerous forked veins given off at right angles from a
prominent rachis (fig. 329, B). This type of frond is recorded from the
Permian of Trienbach (Alsace) by Zeiller[1260], by Renault[1261] and
Zeiller[1262] from the Upper Carboniferous of Autun, and from other
localities. The lamina of the simple leaf reaches a breadth of 6 cm. and a
length of 40 cm. (fig. 329, A); the numerous secondary veins (25–36 per
cm. of lamina) are either at right angles to the rachis or given off at an acute
angle. The mesophyll consists of polygonal cells some of which are
elongated at right angles to the surface of the lamina. A very similar form is
described by Fontaine and White from the Permian of Virginia as T.
Lescuriana[1263].
Page 532
Fig. 329.
A. Taeniopteris multinervis, Weiss. (⅚ nat. size. After Zeiller.)
B. T. multinervis. (Enlarged. After Zeiller.)
C. Lesleya Delafondi. (× 2. After Zeiller.)
It is futile to expect to be able to separate the numerous Taeniopteris
leaves into well-defined species: all we can do is to group the specimens
under different names, using as artificial distinctions such characters as the
shape of the leaf, the number of veins per centimetre, and the prominence of
the rachis. Another Virginian species of Permian age described by Fontaine
and White[1264], T. Newberriana, is said to bear sori, but no satisfactory
information is given as to the nature of these organs. Specimens referred
A. Taeniopteris multinervis, Weiss. (⅚ nat. size. After Zeiller.)
B. T. multinervis. (Enlarged. After Zeiller.)
C. Lesleya Delafondi. (× 2. After Zeiller.)
It is futile to expect to be able to separate the numerous Taeniopteris
leaves into well-defined species: all we can do is to group the specimens
under different names, using as artificial distinctions such characters as the
shape of the leaf, the number of veins per centimetre, and the prominence of
the rachis. Another Virginian species of Permian age described by Fontaine
and White[1264], T. Newberriana, is said to bear sori, but no satisfactory
information is given as to the nature of these organs. Specimens referred
Page 533
with some hesitation to this species and to a similar species, T. coriacea,
have been described by Sellards[1265] from material obtained from Permian
beds in Kansas. The lamina of the simple linear fronds is characterised by
the occurrence of small oval bodies half immersed in the substance of the
leaf between the secondary veins (figs. 330, D, E). One of these bodies is
represented in an apparently dehisced condition in fig. 330, D. Sellards
suggests the possibility that these bodies are sporangia, but, as he points
out, they afford no indication of cellular structure nor are they in direct
connexion with the veins.
Taeniopteris jejunata, Grand’Eury[1266].
This species differs from T. multinervis in its bipinnate fronds; the linear
or oval-linear pinnae are attached by a short stalk to the primary rachis and
reach a length of 25 cm.; the veins are less crowded, 12–15 per centimetre.
T. jejunata is recorded from the Coal-fields of the Loire and
Commentry[1267] in France, from the Lower Permian of Thuringia[1268], and
elsewhere.
Taeniopteris Carnoti, Ren. and Zeiller[1269]. Fig. 330, A.
This species, founded on portions of pinnate fronds from the Coal-field
of Commentry, is characterised by rather broader (25–30 mm.) pinnules,
with short pedicels and a cordate base, reaching a length of 25–30 cm. The
secondary forked veins are more numerous than in T. jejunata. In T.
multinervis the pinnules are still broader and have a stronger midrib.
• • • • •
Several species of Taeniopteris have been described from Triasso-Rhaetic
rocks in Europe, India, Tonkin and elsewhere. In some cases it is practically
impossible to recognise clear specific distinctions between Rhaetic and
Jurassic types.
From the Damuda and Panchet series of India (Triasso-Rhaetic)
Feistmantel has described large sterile fronds as Macrotaeniopteris
Feddeni[1270] which reach a breadth of 20 cm.: these may be compared with
the Indian species Taeniopteris lata Oldham[1271], and to T. gigantea from
the Rhaetic of Franconia[1272] and Scania. A specimen of this species figured
have been described by Sellards[1265] from material obtained from Permian
beds in Kansas. The lamina of the simple linear fronds is characterised by
the occurrence of small oval bodies half immersed in the substance of the
leaf between the secondary veins (figs. 330, D, E). One of these bodies is
represented in an apparently dehisced condition in fig. 330, D. Sellards
suggests the possibility that these bodies are sporangia, but, as he points
out, they afford no indication of cellular structure nor are they in direct
connexion with the veins.
Taeniopteris jejunata, Grand’Eury[1266].
This species differs from T. multinervis in its bipinnate fronds; the linear
or oval-linear pinnae are attached by a short stalk to the primary rachis and
reach a length of 25 cm.; the veins are less crowded, 12–15 per centimetre.
T. jejunata is recorded from the Coal-fields of the Loire and
Commentry[1267] in France, from the Lower Permian of Thuringia[1268], and
elsewhere.
Taeniopteris Carnoti, Ren. and Zeiller[1269]. Fig. 330, A.
This species, founded on portions of pinnate fronds from the Coal-field
of Commentry, is characterised by rather broader (25–30 mm.) pinnules,
with short pedicels and a cordate base, reaching a length of 25–30 cm. The
secondary forked veins are more numerous than in T. jejunata. In T.
multinervis the pinnules are still broader and have a stronger midrib.
• • • • •
Several species of Taeniopteris have been described from Triasso-Rhaetic
rocks in Europe, India, Tonkin and elsewhere. In some cases it is practically
impossible to recognise clear specific distinctions between Rhaetic and
Jurassic types.
From the Damuda and Panchet series of India (Triasso-Rhaetic)
Feistmantel has described large sterile fronds as Macrotaeniopteris
Feddeni[1270] which reach a breadth of 20 cm.: these may be compared with
the Indian species Taeniopteris lata Oldham[1271], and to T. gigantea from
the Rhaetic of Franconia[1272] and Scania. A specimen of this species figured
Page 534
by Nathorst[1273] from Scania has a lamina 33 cm. broad. Other examples are
afforded by M. Wianamattae Feist.[1274] from rocks of the same age in
Australia and by Taeniopteris superba Sap.[1275] from Lower Rhaetic rocks
near Autun.
From the Rhaetic of Tonkin, Zeiller records several species, among
which may be mentioned T. Jourdyi Zeill.[1276] and T. spatulata MacClelland
(fig. 330, B, C). Both have simple fronds. Those of T. Jourdyi reach a length
of 10–40 cm. and a breadth of 10–70 mm.; the rachis is characterised by
crowded and discontinuous transverse folds, and the secondary veins (35–
50 per cm.) are usually at right angles to the rachis. This Tonkin species is
compared by Zeiller with the European Rhaetic species T. tenuinervis
Brauns.
The polymorphism of the fronds is a striking feature: in one case
described by Zeiller the lamina appears to be divided into segments like
those characteristic of the leaf of the Cycadean genus Anomozamites. It is
obviously difficult in many instances to distinguish between detached
Taeniopteroid pinnae of a compound frond and complete simple leaves. In
some compound fern fronds, as in the recent Polypodiaceous genus
Didymochlaena, the pinnules are deciduous, and the same feature
undoubtedly characterised the fronds of many extinct species. A specimen
figured by Zeiller which shows several petioles of T. Jourdyi attached to a
thick stem[1277] demonstrates the simple nature of the leaves. In other cases,
e.g. T. vittata, specimens occur in which the slightly enlarged petiole-base
has a clean-cut surface indicating abscission from a rhizome (fig. 332).
The fronds described by Zeiller as T. spatulata[1278] (fig. 330, B, C)
closely resemble Jurassic leaves from Victoria referred to Taeniopteris
Daintreei McCoy[1279].
afforded by M. Wianamattae Feist.[1274] from rocks of the same age in
Australia and by Taeniopteris superba Sap.[1275] from Lower Rhaetic rocks
near Autun.
From the Rhaetic of Tonkin, Zeiller records several species, among
which may be mentioned T. Jourdyi Zeill.[1276] and T. spatulata MacClelland
(fig. 330, B, C). Both have simple fronds. Those of T. Jourdyi reach a length
of 10–40 cm. and a breadth of 10–70 mm.; the rachis is characterised by
crowded and discontinuous transverse folds, and the secondary veins (35–
50 per cm.) are usually at right angles to the rachis. This Tonkin species is
compared by Zeiller with the European Rhaetic species T. tenuinervis
Brauns.
The polymorphism of the fronds is a striking feature: in one case
described by Zeiller the lamina appears to be divided into segments like
those characteristic of the leaf of the Cycadean genus Anomozamites. It is
obviously difficult in many instances to distinguish between detached
Taeniopteroid pinnae of a compound frond and complete simple leaves. In
some compound fern fronds, as in the recent Polypodiaceous genus
Didymochlaena, the pinnules are deciduous, and the same feature
undoubtedly characterised the fronds of many extinct species. A specimen
figured by Zeiller which shows several petioles of T. Jourdyi attached to a
thick stem[1277] demonstrates the simple nature of the leaves. In other cases,
e.g. T. vittata, specimens occur in which the slightly enlarged petiole-base
has a clean-cut surface indicating abscission from a rhizome (fig. 332).
The fronds described by Zeiller as T. spatulata[1278] (fig. 330, B, C)
closely resemble Jurassic leaves from Victoria referred to Taeniopteris
Daintreei McCoy[1279].
Page 535
Fig. 330.
A. Taeniopteris Carnoti, Ren. and Zeill. (Nat. size. After Renault and Zeiller.)
B. T. spatulata, McClell. (Nat. size. After Zeiller.)
C. T. spatulata. (× 3. After Zeiller.)
D. Supposed sporangium of T. coriacea. (× 15. After Sellards.)
E. T. coriacea. (× 2. After Sellards.)
Whether specifically identical or not, these leaves represent a type
distinguished from the other species of the genus by the small breadth of the
linear-lanceolate or linear-spathulate lamina, which may be 6–15 cm. in
A. Taeniopteris Carnoti, Ren. and Zeill. (Nat. size. After Renault and Zeiller.)
B. T. spatulata, McClell. (Nat. size. After Zeiller.)
C. T. spatulata. (× 3. After Zeiller.)
D. Supposed sporangium of T. coriacea. (× 15. After Sellards.)
E. T. coriacea. (× 2. After Sellards.)
Whether specifically identical or not, these leaves represent a type
distinguished from the other species of the genus by the small breadth of the
linear-lanceolate or linear-spathulate lamina, which may be 6–15 cm. in
Page 536
length and 3–12 mm. broad. The lamina is often characterised by transverse
folds (fig. 330, C).
Taeniopteris Carruthersi. Fig. 331.
1872. Taeniopteris Daintreei, Carruthers, Quart. Journ. Geol. Soc. Vol.
xxviii. Pl. xxvii. fig. 6.
1883. T. Carruthersi, Tenison-Woods, Proc. Linn. Soc. N. S. Wales, Vol.
viii. p. 117.
Fig. 331. Taeniopteris Carruthersi, Ten.-Woods. Nat. size.
The simple fronds included under this specific name are characterised by
a strong midrib from which numerous simple or forked secondary veins are
given off at a right angle or slightly inclined. The breadth of the lamina
decreases gradually towards the petiole. The Australian species named by
McCoy Taeniopteris Daintreei, to which Carruthers referred the
Queensland fossils, has a much narrower and more linear form of frond,
and for this reason Tenison-Woods instituted a new specific name. T.
Carruthersi represents a form of leaf met with in Rhaetic, or possibly Upper
Triassic, rocks in S. Africa[1280] and Australia. A very similar, perhaps an
identical type, was described from Argentina by Geinitz[1281] as T.
folds (fig. 330, C).
Taeniopteris Carruthersi. Fig. 331.
1872. Taeniopteris Daintreei, Carruthers, Quart. Journ. Geol. Soc. Vol.
xxviii. Pl. xxvii. fig. 6.
1883. T. Carruthersi, Tenison-Woods, Proc. Linn. Soc. N. S. Wales, Vol.
viii. p. 117.
Fig. 331. Taeniopteris Carruthersi, Ten.-Woods. Nat. size.
The simple fronds included under this specific name are characterised by
a strong midrib from which numerous simple or forked secondary veins are
given off at a right angle or slightly inclined. The breadth of the lamina
decreases gradually towards the petiole. The Australian species named by
McCoy Taeniopteris Daintreei, to which Carruthers referred the
Queensland fossils, has a much narrower and more linear form of frond,
and for this reason Tenison-Woods instituted a new specific name. T.
Carruthersi represents a form of leaf met with in Rhaetic, or possibly Upper
Triassic, rocks in S. Africa[1280] and Australia. A very similar, perhaps an
identical type, was described from Argentina by Geinitz[1281] as T.
Page 537
mareyiaca: among many other examples of this form of frond may be
mentioned T. immersa[1282] Nath. from the Rhaetic rocks of Scania and T.
virgulata from the Rhaetic of Tonkin[1283].
A comparison of Taeniopteris Carruthersi or various other “species” of
Rhaetic fronds with the Jurassic species T. vittata illustrates the slight and
unimportant differences on which specific separation is based. It is hopeless
to attempt to draw a satisfactory distinction between the numerous
Taeniopteris fronds from Upper Triassic and Jurassic rocks.
Taeniopteris vittata, Brongniart. Fig. 332.
The simple leaves to which Brongniart applied this name are
characteristic of the Inferior Oolite flora of England, and examples of the
same type are recorded from Jurassic rocks of India, Poland, the Arctic
regions, Japan, China, Australia and other countries[1284].
Leaf linear-lanceolate, reaching a length of more than 20 cm. and a breadth of 3 cm. The
lamina increases gradually in breadth from the base and tapers towards the apex. Numerous
secondary veins are given off at right angles from a broad midrib: the lateral veins may be simple
or forked close to their origin, near the margin, or in the intermediate portion, of the lamina.
It is exceedingly difficult to use Taeniopteris leaves of this form as
evidence in regard to the Jurassic or Rhaetic age of plant-bearing strata. The
species T. tenuinervis Brauns, as figured by Schenk[1285] from the Rhaetic
rocks of Germany and Persia, and recorded from several other regions,
presents a close agreement with T. vittata. Oleandridium lentriculiforme
Etheridge[1286] from the Hawkesbury series of Australia is another similar
leaf. The species T. vittata from the Yorkshire coast, represented in fig. 332,
shows a well-preserved petiole with a clean-cut base like that of the petioles
of Oleandra neriiformis and other recent ferns which are detached from the
rhizome by the action of an absciss-layer.
mentioned T. immersa[1282] Nath. from the Rhaetic rocks of Scania and T.
virgulata from the Rhaetic of Tonkin[1283].
A comparison of Taeniopteris Carruthersi or various other “species” of
Rhaetic fronds with the Jurassic species T. vittata illustrates the slight and
unimportant differences on which specific separation is based. It is hopeless
to attempt to draw a satisfactory distinction between the numerous
Taeniopteris fronds from Upper Triassic and Jurassic rocks.
Taeniopteris vittata, Brongniart. Fig. 332.
The simple leaves to which Brongniart applied this name are
characteristic of the Inferior Oolite flora of England, and examples of the
same type are recorded from Jurassic rocks of India, Poland, the Arctic
regions, Japan, China, Australia and other countries[1284].
Leaf linear-lanceolate, reaching a length of more than 20 cm. and a breadth of 3 cm. The
lamina increases gradually in breadth from the base and tapers towards the apex. Numerous
secondary veins are given off at right angles from a broad midrib: the lateral veins may be simple
or forked close to their origin, near the margin, or in the intermediate portion, of the lamina.
It is exceedingly difficult to use Taeniopteris leaves of this form as
evidence in regard to the Jurassic or Rhaetic age of plant-bearing strata. The
species T. tenuinervis Brauns, as figured by Schenk[1285] from the Rhaetic
rocks of Germany and Persia, and recorded from several other regions,
presents a close agreement with T. vittata. Oleandridium lentriculiforme
Etheridge[1286] from the Hawkesbury series of Australia is another similar
leaf. The species T. vittata from the Yorkshire coast, represented in fig. 332,
shows a well-preserved petiole with a clean-cut base like that of the petioles
of Oleandra neriiformis and other recent ferns which are detached from the
rhizome by the action of an absciss-layer.
Page 538
Fig. 332. Taeniopteris vittata. (British Museum No. 39217. ⅔ nat. size.)
A broader form of frond with similar venation was described by Lindley
and Hutton[1287] as Taeniopteris major. An examination of the type-specimen
from the Inferior Oolite of Yorkshire, now in the Manchester Museum, led
me to doubt the necessity of specific separation from T. vittata[1288].
A broader form of frond with similar venation was described by Lindley
and Hutton[1287] as Taeniopteris major. An examination of the type-specimen
from the Inferior Oolite of Yorkshire, now in the Manchester Museum, led
me to doubt the necessity of specific separation from T. vittata[1288].
Page 539
A smaller frond of the same general type as T. vittata is recorded from
Wealden strata of North Germany and England under the name T.
Beyrichii[1289].
Weichselia.
This generic name was instituted by Stiehler[1290] for impressions of
bipinnate sterile fronds, presumably ferns, from Lower Cretaceous rocks
near Quedlinburg. The same type of leaf from English Wealden beds had
previously been referred by Mantell and other authors to Pecopteris, and by
Brongniart to his genus Lonchopteris[1291]. It is, however, advisable to
follow Nathorst’s example[1292] and restrict the latter name to Palaeozoic
species. As already suggested, it would obviate confusion to substitute a
new generic designation for Lonchopteris in the case of Triassic species
which are probably members of the Osmundaceae. The type-species of
Stiehler, Weichselia Ludowicae[1293], does not differ in any important
character from Weichselia Mantelli, the species originally described by
Stokes and Webb from the Wealden of England as Pecopteris reticulata.
Weichselia Mantelli (Brongn.)[1294]. Fig. 333.
1824. Pecopteris reticulata, Stokes and Webb, Trans. Geol. Soc. [2]. Vol. i. p. 423, Pls. xlvi. xlvii.
1828. Lonchopteris Mantelli, Brongniart, Prod. p. 6; Hist. vég. foss. p. 369, Pl. cxxxi.
1894. Weichselia Mantelli, Seward, Wealden Flora, Vol. i. p. 114. Pl. x. fig. 3.
1899. Weichselia reticulata, Fontaine, in Ward, Ann. Rep. U. S. Geol. Surv. p. 651.
Frond bipinnate, rachis broad; pinnae very long, of uniform breadth and with prominent axes;
pinnules crowded, entire, with obtuse apex, usually oblong but more or less triangular or rounded
towards the distal ends of the pinnae. The pinnules, which may reach a length of 9 cm., are
characterised by a fleshy lamina attached by the whole breadth of the base; the two rows of
segments on each secondary rachis are usually inclined towards one another so that they form
with the axis of the pinna a wide-open V instead of lying in one plane (fig. 333, C). From a
median rib are given off numerous anastomosing branches (fig. 333, B).
Wealden strata of North Germany and England under the name T.
Beyrichii[1289].
Weichselia.
This generic name was instituted by Stiehler[1290] for impressions of
bipinnate sterile fronds, presumably ferns, from Lower Cretaceous rocks
near Quedlinburg. The same type of leaf from English Wealden beds had
previously been referred by Mantell and other authors to Pecopteris, and by
Brongniart to his genus Lonchopteris[1291]. It is, however, advisable to
follow Nathorst’s example[1292] and restrict the latter name to Palaeozoic
species. As already suggested, it would obviate confusion to substitute a
new generic designation for Lonchopteris in the case of Triassic species
which are probably members of the Osmundaceae. The type-species of
Stiehler, Weichselia Ludowicae[1293], does not differ in any important
character from Weichselia Mantelli, the species originally described by
Stokes and Webb from the Wealden of England as Pecopteris reticulata.
Weichselia Mantelli (Brongn.)[1294]. Fig. 333.
1824. Pecopteris reticulata, Stokes and Webb, Trans. Geol. Soc. [2]. Vol. i. p. 423, Pls. xlvi. xlvii.
1828. Lonchopteris Mantelli, Brongniart, Prod. p. 6; Hist. vég. foss. p. 369, Pl. cxxxi.
1894. Weichselia Mantelli, Seward, Wealden Flora, Vol. i. p. 114. Pl. x. fig. 3.
1899. Weichselia reticulata, Fontaine, in Ward, Ann. Rep. U. S. Geol. Surv. p. 651.
Frond bipinnate, rachis broad; pinnae very long, of uniform breadth and with prominent axes;
pinnules crowded, entire, with obtuse apex, usually oblong but more or less triangular or rounded
towards the distal ends of the pinnae. The pinnules, which may reach a length of 9 cm., are
characterised by a fleshy lamina attached by the whole breadth of the base; the two rows of
segments on each secondary rachis are usually inclined towards one another so that they form
with the axis of the pinna a wide-open V instead of lying in one plane (fig. 333, C). From a
median rib are given off numerous anastomosing branches (fig. 333, B).
Page 540
Fig. 333. Weichselia Mantelli.
A. Part of a frond from the Wealden of Sussex, England. (British Museum; v. 2630. ¾ nat.
size.)
B. Pinnule from Bernissart, Belgium (× 3).
C. Weichselia erratica, Nath. Section of pinna. (After Nathorst.)
This characteristic Wealden species is recorded from England, Germany,
France, Belgium, Austria, Russia, Bornholm, North America, and Japan. It
is by no means certain that Weichselia Mantelli is a true fern: no
satisfactory evidence of fructification has been adduced.
The broad and strong rachis is comparable with that of a Cycadean leaf
and the thick lamina suggests a plant of xerophilous habit. I have retained
A. Part of a frond from the Wealden of Sussex, England. (British Museum; v. 2630. ¾ nat.
size.)
B. Pinnule from Bernissart, Belgium (× 3).
C. Weichselia erratica, Nath. Section of pinna. (After Nathorst.)
This characteristic Wealden species is recorded from England, Germany,
France, Belgium, Austria, Russia, Bornholm, North America, and Japan. It
is by no means certain that Weichselia Mantelli is a true fern: no
satisfactory evidence of fructification has been adduced.
The broad and strong rachis is comparable with that of a Cycadean leaf
and the thick lamina suggests a plant of xerophilous habit. I have retained
Page 541
the specific name Mantelli on the ground of long established usage instead
of following Fontaine in his adherence to strict priority.
Glossopteris.
The name Glossopteris was proposed by Brongniart in 1822[1295] for an
imperfect leaf-impression which he called Filicites (Glossopteris) dubius,
but the specimen so named has since been identified as part of a sporophyll
of a Lepidostrobus. The author of the genus afterwards published[1296] a
diagnosis, based on well-preserved leaves from Permo-Carboniferous rocks
in Australia and India, of the type-species Glossopteris Browniana, the
Indian examples being distinguished as G. Browniana var. indica while the
Australian form was named G. Browniana var. australasica. Schimper[1297]
afterwards raised the Indian fossils to specific rank as G. indica though
some authors[1298] have continued to consider the two forms as insufficiently
distinct to be regarded as different species.
The genus Glossopteris may be defined as follows:
Leaves simple, varying considerably in size, shape, and venation characters, but almost
without exception characterised by repeatedly anastomosing lateral veins. The leaves are of two
kinds: (i) foliage leaves; apparently always sterile, usually spathulate, with an obtuse apex, a
well-marked midrib which may persist to the apex or die out in the upper half of the lamina,
characterised by its slight prominence and comparatively great breadth especially in the basal
part of the frond. In most cases the lamina extends as a narrow margin to the leaf-base, but in a
few forms there is a short petiole (fig. 334). Though usually spathulate, the frond may be linear-
lanceolate, or ovate; the apex is sometimes acute. Leaves vary in length from 3 to 40 cm. and
may in larger forms have a breadth of 10 cm. Numerous lateral veins curve upwards and
outwards to the margin of the lamina or pursue a straight course almost at right-angles to the
midrib. (ii) Scale-leaves[1299] which differ from the foliage-leaves in their much smaller size and
in the absence of a midrib; they are deltoid, oval or cordate in shape and generally terminate in an
acute apex; the edge of the lamina may be slightly incurved so that the leaf presents a convex
upper surface supplied with anastomosing veins. The scale-leaves, which vary in length from
about 1 to 6 cm., probably acted as sporophylls. The only evidence as to the nature of the
fructification so far obtained is represented by empty sporangium-like organs (1·2–1·5 mm. long
by 0·6–0·8 mm. broad) frequently associated with the scale-leaves[1300].
The leaves, in some cases at least, were borne near together on a cylindrical stem or rhizome
which produced branched adventitious roots[1301]. The fossils long known as Vertebraria were
recognised by Zeiller[1302] and by Oldham[1303] as the stems of Glossopteris.
The systematic position of Glossopteris must for the present be left an
open question. Though usually spoken of as a fern, it is noteworthy that
despite the enormous abundance of its foliage leaves in the Permo-
of following Fontaine in his adherence to strict priority.
Glossopteris.
The name Glossopteris was proposed by Brongniart in 1822[1295] for an
imperfect leaf-impression which he called Filicites (Glossopteris) dubius,
but the specimen so named has since been identified as part of a sporophyll
of a Lepidostrobus. The author of the genus afterwards published[1296] a
diagnosis, based on well-preserved leaves from Permo-Carboniferous rocks
in Australia and India, of the type-species Glossopteris Browniana, the
Indian examples being distinguished as G. Browniana var. indica while the
Australian form was named G. Browniana var. australasica. Schimper[1297]
afterwards raised the Indian fossils to specific rank as G. indica though
some authors[1298] have continued to consider the two forms as insufficiently
distinct to be regarded as different species.
The genus Glossopteris may be defined as follows:
Leaves simple, varying considerably in size, shape, and venation characters, but almost
without exception characterised by repeatedly anastomosing lateral veins. The leaves are of two
kinds: (i) foliage leaves; apparently always sterile, usually spathulate, with an obtuse apex, a
well-marked midrib which may persist to the apex or die out in the upper half of the lamina,
characterised by its slight prominence and comparatively great breadth especially in the basal
part of the frond. In most cases the lamina extends as a narrow margin to the leaf-base, but in a
few forms there is a short petiole (fig. 334). Though usually spathulate, the frond may be linear-
lanceolate, or ovate; the apex is sometimes acute. Leaves vary in length from 3 to 40 cm. and
may in larger forms have a breadth of 10 cm. Numerous lateral veins curve upwards and
outwards to the margin of the lamina or pursue a straight course almost at right-angles to the
midrib. (ii) Scale-leaves[1299] which differ from the foliage-leaves in their much smaller size and
in the absence of a midrib; they are deltoid, oval or cordate in shape and generally terminate in an
acute apex; the edge of the lamina may be slightly incurved so that the leaf presents a convex
upper surface supplied with anastomosing veins. The scale-leaves, which vary in length from
about 1 to 6 cm., probably acted as sporophylls. The only evidence as to the nature of the
fructification so far obtained is represented by empty sporangium-like organs (1·2–1·5 mm. long
by 0·6–0·8 mm. broad) frequently associated with the scale-leaves[1300].
The leaves, in some cases at least, were borne near together on a cylindrical stem or rhizome
which produced branched adventitious roots[1301]. The fossils long known as Vertebraria were
recognised by Zeiller[1302] and by Oldham[1303] as the stems of Glossopteris.
The systematic position of Glossopteris must for the present be left an
open question. Though usually spoken of as a fern, it is noteworthy that
despite the enormous abundance of its foliage leaves in the Permo-
Page 542
Carboniferous strata of India, Australia, South Africa, and South America,
no single example has been discovered which shows undoubted remains of
sori or sporangia. Many authors have described fertile leaves of
Glossopteris; but it was not until Arber’s discovery of sporangia in close
association with the scale-leaves that any light was thrown on the nature of
the reproductive organs.
The probability is that Glossopteris was not a true fern but a member of
that large and ever-increasing class, the Pteridosperms. This opinion is
based largely on negative evidence. Such sporangia as have been described
may have contained microspores and the plant may have been
heterosporous. The occurrence of seeds in association with Glossopteris
fronds recorded by more than one writer[1304], though by no means decisive
and possibly the result of chance association, is favourable to this view. Dr
White[1305] has suggested that the small leaves described by Zeiller[1306] as
Ottokaria bengalensis from Lower Gondwana (Permo-Carboniferous) rocks
of India, and similar fossils recorded by himself from Brazil as O. ovalis,
may represent “sporangiferous” organs of Glossopteris or Gangamopteris,
“both of which are probably pteridospermic.” There is, however, no
conclusive evidence in support of this suggestion.
The genus, whatever its position may be, has a special interest for the
geologist and for the student of plant distribution; it is a characteristic
member of a Permo-Carboniferous flora which flourished over an enormous
area, including India, South Africa,—extending from Cape Colony to
Rhodesia and German East Africa[1307],—Australia, and South America[1308].
This flora, known as the Glossopteris flora, differed considerably in its
component genera from that which overspread Europe and North America
and some more southern regions in the Upper Carboniferous and Permian
periods.
The discovery by Amalitzky[1309] of Glossopteris, and other genera
characteristic of the Glossopteris flora, in the Upper Permian rocks in
Vologda (Russia) demonstrates the existence of a northern outpost of the
southern botanical province, and Zeiller’s discovery of the genus in the
Rhaetic flora of Tonkin[1310] shows that Glossopteris persisted beyond the
limits of the Palaeozoic epoch. Dr David White[1311] has recently proposed to
re-christen the Glossopteris flora the Gangamopteris flora on the ground
that Gangamopteris is strictly Palaeozoic in its range, whereas Glossopteris
no single example has been discovered which shows undoubted remains of
sori or sporangia. Many authors have described fertile leaves of
Glossopteris; but it was not until Arber’s discovery of sporangia in close
association with the scale-leaves that any light was thrown on the nature of
the reproductive organs.
The probability is that Glossopteris was not a true fern but a member of
that large and ever-increasing class, the Pteridosperms. This opinion is
based largely on negative evidence. Such sporangia as have been described
may have contained microspores and the plant may have been
heterosporous. The occurrence of seeds in association with Glossopteris
fronds recorded by more than one writer[1304], though by no means decisive
and possibly the result of chance association, is favourable to this view. Dr
White[1305] has suggested that the small leaves described by Zeiller[1306] as
Ottokaria bengalensis from Lower Gondwana (Permo-Carboniferous) rocks
of India, and similar fossils recorded by himself from Brazil as O. ovalis,
may represent “sporangiferous” organs of Glossopteris or Gangamopteris,
“both of which are probably pteridospermic.” There is, however, no
conclusive evidence in support of this suggestion.
The genus, whatever its position may be, has a special interest for the
geologist and for the student of plant distribution; it is a characteristic
member of a Permo-Carboniferous flora which flourished over an enormous
area, including India, South Africa,—extending from Cape Colony to
Rhodesia and German East Africa[1307],—Australia, and South America[1308].
This flora, known as the Glossopteris flora, differed considerably in its
component genera from that which overspread Europe and North America
and some more southern regions in the Upper Carboniferous and Permian
periods.
The discovery by Amalitzky[1309] of Glossopteris, and other genera
characteristic of the Glossopteris flora, in the Upper Permian rocks in
Vologda (Russia) demonstrates the existence of a northern outpost of the
southern botanical province, and Zeiller’s discovery of the genus in the
Rhaetic flora of Tonkin[1310] shows that Glossopteris persisted beyond the
limits of the Palaeozoic epoch. Dr David White[1311] has recently proposed to
re-christen the Glossopteris flora the Gangamopteris flora on the ground
that Gangamopteris is strictly Palaeozoic in its range, whereas Glossopteris
Page 543
persisted into the Mesozoic era; this is perhaps hardly a sufficient reason for
giving up so well established a title as the Glossopteris flora. A fuller
account of this southern flora must be reserved for another volume.
Glossopteris Browniana, Brongniart[1312]. Figs. 334–36.
The specific name Browniana is now applied to obtusely pointed leaves
which sometimes reach a length of 15 cm., but are usually rather shorter. In
form and venation they closely resemble the leaves of the recent genus
Antrophyum and species of Acrostichum. The comparatively broad midrib
may be replaced in its proximal portion by several parallel veins: from it are
given off numerous lateral veins which form a reticulum characterised by
meshes approximately equal in size and elongated in a direction parallel to
the general course of the secondary veins (fig. 334).
giving up so well established a title as the Glossopteris flora. A fuller
account of this southern flora must be reserved for another volume.
Glossopteris Browniana, Brongniart[1312]. Figs. 334–36.
The specific name Browniana is now applied to obtusely pointed leaves
which sometimes reach a length of 15 cm., but are usually rather shorter. In
form and venation they closely resemble the leaves of the recent genus
Antrophyum and species of Acrostichum. The comparatively broad midrib
may be replaced in its proximal portion by several parallel veins: from it are
given off numerous lateral veins which form a reticulum characterised by
meshes approximately equal in size and elongated in a direction parallel to
the general course of the secondary veins (fig. 334).
Page 544
Fig. 334. Glossopteris Browniana, Brongn. A. Nat. size: B × 3½.
The drawings, originally published by Zeiller[1313], reproduced in fig. 335
illustrate the venation and its range of variation; the meshes are usually
hexagonal and arranged as shown in figs. A and B, but occasionally (fig.
335, C) they follow a more steeply inclined course.
Small leaves with a more or less distinct midrib, 2–3 cm. in length,
supply transitional stages between foliage- and scale-leaves. In the true
scale-leaves spreading and occasionally anastomosing veins take the place
of the midrib and lateral veins of the ordinary frond. McCoy[1314] in
describing some Australian specimens of Glossopteris in 1847 spoke of
scale-like appendages of the rhizome which he compared with the large
ramenta of Acrostichum and other ferns. It was, however, Zeiller[1315] who
first recognised the leaf-nature of these scales and adequately described
them; additional figures of scale-leaves have been published by Mr
The drawings, originally published by Zeiller[1313], reproduced in fig. 335
illustrate the venation and its range of variation; the meshes are usually
hexagonal and arranged as shown in figs. A and B, but occasionally (fig.
335, C) they follow a more steeply inclined course.
Small leaves with a more or less distinct midrib, 2–3 cm. in length,
supply transitional stages between foliage- and scale-leaves. In the true
scale-leaves spreading and occasionally anastomosing veins take the place
of the midrib and lateral veins of the ordinary frond. McCoy[1314] in
describing some Australian specimens of Glossopteris in 1847 spoke of
scale-like appendages of the rhizome which he compared with the large
ramenta of Acrostichum and other ferns. It was, however, Zeiller[1315] who
first recognised the leaf-nature of these scales and adequately described
them; additional figures of scale-leaves have been published by Mr
Page 545
Arber[1316] and by myself[1317]. The importance of these small leaves has been
considerably increased by Mr Arber’s discovery of associated sporangia
which, as he suggests, were probably borne on their lower concave surface.
Fig. 335. Glossopteris Browniana, Brongn. (After Zeiller. × 2.)
The sporangia (fig. 336) are compared by Arber with the microsporangia
of recent Cycads and with the Palaeozoic sporangia described by Zeiller as
Discopteris Rallii (fig. 256, D); the latter are distinguished by the well-
defined group of thicker walled cells representing the annulus of true fern
sporangia. We know nothing as to the contents of the Glossopteris
sporangia, whether they contained microspores or whether they are the
spore-capsules of a homosporous plant.
considerably increased by Mr Arber’s discovery of associated sporangia
which, as he suggests, were probably borne on their lower concave surface.
Fig. 335. Glossopteris Browniana, Brongn. (After Zeiller. × 2.)
The sporangia (fig. 336) are compared by Arber with the microsporangia
of recent Cycads and with the Palaeozoic sporangia described by Zeiller as
Discopteris Rallii (fig. 256, D); the latter are distinguished by the well-
defined group of thicker walled cells representing the annulus of true fern
sporangia. We know nothing as to the contents of the Glossopteris
sporangia, whether they contained microspores or whether they are the
spore-capsules of a homosporous plant.
Page 546
Fig. 336. Glossopteris Browniana, Brongn. Sporangia. (× 30). After Arber.
The rhizome of Glossopteris Browniana has been described in detail by
Zeiller, who first demonstrated that the fossils originally assigned by
Royle[1318] to the genus Vertebraria represent the stem of this and, as we
now know, of some other species of Glossopteris. Vertebraria occurs in
abundance in Permo-Carboniferous strata in association with Glossopteris;
the differences between Australian, Indian, and South forms, though
expressed by specific names, are insignificant. The stems are usually
preserved in the form of flattened, single or branched, axes sometimes
bearing slender branched roots and characterised by one or two, or less
frequently three, longitudinal grooves or ridges (fig. 337) from which
lateral grooves or ridges are given off at right angles, dividing the surface
into more or less rectangular areas 1 cm. or more in length. The surface of
these areas is often slightly convex and in some specimens the outlines of
cells may be detected. Mr Oldham has described some interesting examples
of Vertebraria from India in which the longitudinal and transverse grooves
are occupied by a dark brown ferruginous substance or by the carbonised
remains of plant-tissues (fig. 338, C, D). In transverse section, a Vertebraria
The rhizome of Glossopteris Browniana has been described in detail by
Zeiller, who first demonstrated that the fossils originally assigned by
Royle[1318] to the genus Vertebraria represent the stem of this and, as we
now know, of some other species of Glossopteris. Vertebraria occurs in
abundance in Permo-Carboniferous strata in association with Glossopteris;
the differences between Australian, Indian, and South forms, though
expressed by specific names, are insignificant. The stems are usually
preserved in the form of flattened, single or branched, axes sometimes
bearing slender branched roots and characterised by one or two, or less
frequently three, longitudinal grooves or ridges (fig. 337) from which
lateral grooves or ridges are given off at right angles, dividing the surface
into more or less rectangular areas 1 cm. or more in length. The surface of
these areas is often slightly convex and in some specimens the outlines of
cells may be detected. Mr Oldham has described some interesting examples
of Vertebraria from India in which the longitudinal and transverse grooves
are occupied by a dark brown ferruginous substance or by the carbonised
remains of plant-tissues (fig. 338, C, D). In transverse section, a Vertebraria
Page 547
cast appears to be divided into a number of wedge-shaped segments
radiating from a common centre. Prof. Zeiller[1319] has figured specimens of
Vertebraria with portions of Glossopteris fronds still attached.
Fig. 337. Vertebraria indica, Royle. Nat. size. (After Feistmantel.)
The rhizome of Glossopteris, as represented by the Vertebraria casts, is
aptly compared by Zeiller[1320] with that of the recent Polypodiaceous fern
Onoclea struthiopteris. Sections of the recent stem (fig. 338, E, F) show
that the form is irregularly stellate owing to the presence of prominent
wings which anastomose laterally at intervals as shown by the examination
of a series of sections. The leaf-traces are derived from the steles of
adjacent wings. Fig. 338 (B and A) represents somewhat diagrammatically
a longitudinal and transverse view of a Vertebraria; the radiating arms
represented in the transverse section (fig. A) are the stem ribs or wings and
radiating from a common centre. Prof. Zeiller[1319] has figured specimens of
Vertebraria with portions of Glossopteris fronds still attached.
Fig. 337. Vertebraria indica, Royle. Nat. size. (After Feistmantel.)
The rhizome of Glossopteris, as represented by the Vertebraria casts, is
aptly compared by Zeiller[1320] with that of the recent Polypodiaceous fern
Onoclea struthiopteris. Sections of the recent stem (fig. 338, E, F) show
that the form is irregularly stellate owing to the presence of prominent
wings which anastomose laterally at intervals as shown by the examination
of a series of sections. The leaf-traces are derived from the steles of
adjacent wings. Fig. 338 (B and A) represents somewhat diagrammatically
a longitudinal and transverse view of a Vertebraria; the radiating arms
represented in the transverse section (fig. A) are the stem ribs or wings and
Page 548
the segments between them are intrusions of sedimentary material. The
rectangular areas characteristic of the surface of a Vertebraria are the
intruded segments of rock: these are separated at intervals by transverse
grooves, which mark the course of vascular strands given off at each
anastomosis of the longitudinal wings to supply the leaves.
Fig. 338.
A, B. Vertebraria indica. (After Zeiller.)
C, D. V. indica. (Nat. size. After Oldham.)
E, F. Onoclea struthiopteris. (× 2. After Zeiller.)
Mr Oldham, who discovered the connexion between Glossopteris and
Vertebraria independently of Dr Zeiller, does not agree with the
interpretation of the structural features of the rhizome which Zeiller bases
on a comparison between Vertebraria and Onoclea struthiopteris.
Oldham[1321] describes Vertebraria as consisting of a central axis “joined to
rectangular areas characteristic of the surface of a Vertebraria are the
intruded segments of rock: these are separated at intervals by transverse
grooves, which mark the course of vascular strands given off at each
anastomosis of the longitudinal wings to supply the leaves.
Fig. 338.
A, B. Vertebraria indica. (After Zeiller.)
C, D. V. indica. (Nat. size. After Oldham.)
E, F. Onoclea struthiopteris. (× 2. After Zeiller.)
Mr Oldham, who discovered the connexion between Glossopteris and
Vertebraria independently of Dr Zeiller, does not agree with the
interpretation of the structural features of the rhizome which Zeiller bases
on a comparison between Vertebraria and Onoclea struthiopteris.
Oldham[1321] describes Vertebraria as consisting of a central axis “joined to
Page 549
an outer rind by a series of radial septa,” the spaces between the septa being
divided into chambers by transverse partitions. His view is that the rhizome
of Glossopteris was a cylindrical organ and not an irregularly winged axis
like the stem of Onoclea. Zeiller[1322] has replied in detail to Oldham’s
interpretation and adheres to his original view, that the rhizome consisted of
a solid axis with radial wings or flanges which at intervals anastomosed
transversely in pairs at the nodes. It may, however, be possible that the
spaces between the longitudinal and transverse grooves on a Vertebraria
axis, which have been filled with the surrounding rock, were originally
occupied in part at least by secondary wood, and the transverse strips of
carbonaceous material[1323] lying in the grooves may represent medullary-
ray tissue and accompanying leaf-traces. The longitudinal striations seen in
some specimens of Vertebraria on the areas between the grooves may be
the impressions of woody tissue. It is impossible without the aid of more
perfectly preserved material to arrive at a satisfactory conception of the
structural features of a complete Glossopteris rhizome.
divided into chambers by transverse partitions. His view is that the rhizome
of Glossopteris was a cylindrical organ and not an irregularly winged axis
like the stem of Onoclea. Zeiller[1322] has replied in detail to Oldham’s
interpretation and adheres to his original view, that the rhizome consisted of
a solid axis with radial wings or flanges which at intervals anastomosed
transversely in pairs at the nodes. It may, however, be possible that the
spaces between the longitudinal and transverse grooves on a Vertebraria
axis, which have been filled with the surrounding rock, were originally
occupied in part at least by secondary wood, and the transverse strips of
carbonaceous material[1323] lying in the grooves may represent medullary-
ray tissue and accompanying leaf-traces. The longitudinal striations seen in
some specimens of Vertebraria on the areas between the grooves may be
the impressions of woody tissue. It is impossible without the aid of more
perfectly preserved material to arrive at a satisfactory conception of the
structural features of a complete Glossopteris rhizome.
Page 550
Fig. 339. Glossopteris fronds attached to rhizome. (From a specimen lent by Dr
Mohlengraaff. Considerably reduced.)
In the specimen of Glossopteris Browniana shown in fig. 339 several
leaves are attached to an axis which shows none of the surface-features of
Vertebraria. I am indebted to the kindness of Dr Mohlengraaff of Delft for
the loan of this specimen which was obtained from Permo-Carboniferous
rocks in the Transvaal. An axis figured by Etheridge[1324] from an Australian
locality bears a tuft of Glossopteris leaves, possibly G. Browniana; in place
of the rectangular areas characteristic of Vertebraria it shows transversely
Mohlengraaff. Considerably reduced.)
In the specimen of Glossopteris Browniana shown in fig. 339 several
leaves are attached to an axis which shows none of the surface-features of
Vertebraria. I am indebted to the kindness of Dr Mohlengraaff of Delft for
the loan of this specimen which was obtained from Permo-Carboniferous
rocks in the Transvaal. An axis figured by Etheridge[1324] from an Australian
locality bears a tuft of Glossopteris leaves, possibly G. Browniana; in place
of the rectangular areas characteristic of Vertebraria it shows transversely
Page 551
elongated leaf-scars or, on the internal cast, imbricate rod-like projections
which Etheridge suggests represent vascular bundles.
Glossopteris indica, Schimper. Figs. 340, A, 341.
It is a question of secondary importance whether or not the fronds which
Brongniart spoke of as a variety of Glossopteris Browniana should be
recognised as specifically distinct. The careful examination by Zeiller of the
venation characters has, however, afforded justification for separating G.
Browniana and G. indica. We must admit that the slight and not very
constant differences in the size and form of the meshes produced by the
anastomosing of the lateral veins are characters which cannot be recognised
as having more than a secondary value, though, as a matter of convenience,
we employ them as aids to determination. The arbitrary separation of sterile
leaves, which differ by small degrees from one another in form and in the
details of venation, by the application of specific names is a thankless task
necessitated by custom and convenience; it is, however, idle to ignore the
artificial basis of such separation. Mr Arber has recently published, in his
valuable Glossopteris Flora, an analytical key which serves to facilitate the
description and determination of different types of frond[1325].
which Etheridge suggests represent vascular bundles.
Glossopteris indica, Schimper. Figs. 340, A, 341.
It is a question of secondary importance whether or not the fronds which
Brongniart spoke of as a variety of Glossopteris Browniana should be
recognised as specifically distinct. The careful examination by Zeiller of the
venation characters has, however, afforded justification for separating G.
Browniana and G. indica. We must admit that the slight and not very
constant differences in the size and form of the meshes produced by the
anastomosing of the lateral veins are characters which cannot be recognised
as having more than a secondary value, though, as a matter of convenience,
we employ them as aids to determination. The arbitrary separation of sterile
leaves, which differ by small degrees from one another in form and in the
details of venation, by the application of specific names is a thankless task
necessitated by custom and convenience; it is, however, idle to ignore the
artificial basis of such separation. Mr Arber has recently published, in his
valuable Glossopteris Flora, an analytical key which serves to facilitate the
description and determination of different types of frond[1325].
Page 552
Fig. 340.
A. Glossopteris indica, Schimper. (½ nat. size.)
B. Glossopteris angustifolia, Brongniart. (Nat. size.) From Arber, after Feistmantel.
The large leaves of Glossopteris indica, reaching a length in extreme
cases of 40 cm. and a breadth of 10 cm., are characterised by a rather
greater regularity in the arrangement of the meshes and by the greater
parallelism of the upper and lower sides of each mesh (fig. 341) and by less
difference in size between the venation meshes than in G. Browniana, the
leaves of which are usually smaller. The relatively thick epidermis consists
of rectangular cells with stomata in depressions[1326]. The scale-leaves[1327],
A. Glossopteris indica, Schimper. (½ nat. size.)
B. Glossopteris angustifolia, Brongniart. (Nat. size.) From Arber, after Feistmantel.
The large leaves of Glossopteris indica, reaching a length in extreme
cases of 40 cm. and a breadth of 10 cm., are characterised by a rather
greater regularity in the arrangement of the meshes and by the greater
parallelism of the upper and lower sides of each mesh (fig. 341) and by less
difference in size between the venation meshes than in G. Browniana, the
leaves of which are usually smaller. The relatively thick epidermis consists
of rectangular cells with stomata in depressions[1326]. The scale-leaves[1327],
Page 553
rather larger than those of G. Browniana, are more or less rhomboidal with
rounded angles and reach a length of 1·5–6 cm. and a breadth of 1·5–2·5
cm. The rhizome is practically identical with that of G. Browniana[1328].
Fig. 341. Glossopteris indica, Schimp. (× 1½.) From Arber, after Zeiller.
This species occurs in great abundance in the Permo-Carboniferous rocks
of India, Australia, and in various parts of South Africa, and elsewhere. It
has been recognised also by Amalitzky[1329] in Upper Permian beds in Russia
and by Zeiller in the Rhaetic series of Tonkin[1330].
Fig. 342. Glossopteris angustifolia var. taeniopteroides. (× 3½.)
Glossopteris angustifolia, Brongniart. Figs. 340, B; 342.
rounded angles and reach a length of 1·5–6 cm. and a breadth of 1·5–2·5
cm. The rhizome is practically identical with that of G. Browniana[1328].
Fig. 341. Glossopteris indica, Schimp. (× 1½.) From Arber, after Zeiller.
This species occurs in great abundance in the Permo-Carboniferous rocks
of India, Australia, and in various parts of South Africa, and elsewhere. It
has been recognised also by Amalitzky[1329] in Upper Permian beds in Russia
and by Zeiller in the Rhaetic series of Tonkin[1330].
Fig. 342. Glossopteris angustifolia var. taeniopteroides. (× 3½.)
Glossopteris angustifolia, Brongniart. Figs. 340, B; 342.
Page 554
It is convenient to retain this designation for linear fronds with an acute
or obtuse apex and a venation-reticulum composed of long and narrow
meshes (fig. 340, B). It is by no means unlikely, as Arber suggests, that the
same plant may have produced leaves of the G. indica type and narrower
fronds which conform to G. angustifolia. In his description of some Indian
specimens of G. indica, Zeiller draws attention to the variation exhibited in
regard to the extent of anastomosing between the secondary veins: some
examples with very few cross-connexions agree more closely with
Taeniopteris than with Glossopteris as usually defined[1331]. The venation
shown in fig. 342 illustrates an extreme case of what is almost certainly a
Glossopteris leaf of the G. angustifolia type. This specimen, which was
discovered by Mr Leslie in the Permo-Carboniferous sandstone of
Vereeniging (Transvaal), has been referred to a variety of Brongniart’s
species as G. angustifolia var. taeniopteroides[1332] on account of the almost
complete absence of any cross-connexions. The reference to Glossopteris,
which my friend Dr Zeiller suggested, is amply justified by the form of the
leaf as a whole, by the angle at which the lateral veins leave the midrib, a
feature in contrast to the wider angle at which the lateral veins are usually
given off in Taeniopteris (figs. 329, 332), and by the similarity to the Indian
specimens already mentioned. Several authors have described leaves or
leaflets under the generic name Megalopteris[1333] from Carboniferous and
Permian rocks which bear a close resemblance to the South African variety,
but in some cases at least Megalopteris is known to be a pinnate and not a
simple leaf. The leaf figured by Jack and Etheridge as Taeniopteris sp.[1334]
from Queensland may also be an example of Glossopteris. Comparison may
be made also with the Palaeozoic leaves described in the first instance by
Lesquereux and more recently by Renault and Zeiller as species of
Lesleya[1335] (fig. 347).
or obtuse apex and a venation-reticulum composed of long and narrow
meshes (fig. 340, B). It is by no means unlikely, as Arber suggests, that the
same plant may have produced leaves of the G. indica type and narrower
fronds which conform to G. angustifolia. In his description of some Indian
specimens of G. indica, Zeiller draws attention to the variation exhibited in
regard to the extent of anastomosing between the secondary veins: some
examples with very few cross-connexions agree more closely with
Taeniopteris than with Glossopteris as usually defined[1331]. The venation
shown in fig. 342 illustrates an extreme case of what is almost certainly a
Glossopteris leaf of the G. angustifolia type. This specimen, which was
discovered by Mr Leslie in the Permo-Carboniferous sandstone of
Vereeniging (Transvaal), has been referred to a variety of Brongniart’s
species as G. angustifolia var. taeniopteroides[1332] on account of the almost
complete absence of any cross-connexions. The reference to Glossopteris,
which my friend Dr Zeiller suggested, is amply justified by the form of the
leaf as a whole, by the angle at which the lateral veins leave the midrib, a
feature in contrast to the wider angle at which the lateral veins are usually
given off in Taeniopteris (figs. 329, 332), and by the similarity to the Indian
specimens already mentioned. Several authors have described leaves or
leaflets under the generic name Megalopteris[1333] from Carboniferous and
Permian rocks which bear a close resemblance to the South African variety,
but in some cases at least Megalopteris is known to be a pinnate and not a
simple leaf. The leaf figured by Jack and Etheridge as Taeniopteris sp.[1334]
from Queensland may also be an example of Glossopteris. Comparison may
be made also with the Palaeozoic leaves described in the first instance by
Lesquereux and more recently by Renault and Zeiller as species of
Lesleya[1335] (fig. 347).
Page 555
Fig. 343. Blechnoxylon talbragarense, Eth.: s, scale-leaves; x, secondary xylem. (After
Etheridge. A × 2; B × 3; C much enlarged.)
Blechnoxylon talbragarense, Etheridge. Fig. 343.
Under this name Etheridge[1336] described some specimens from the
Permo-Carboniferous Coal-Measures of New South Wales, which he
regards as a fern, comparable, in the possession of a cylinder of secondary
xylem, with the recent genus Botrychium and with Lyginodendron and other
members of the Cycadofilices. The slender axis (1–3 mm. in diameter)
appears to consist of a zone of radially disposed tissue (fig. 343, C, x),
which is probably of the nature of secondary xylem, enclosing a pith and
surrounded externally by imperfectly preserved remnants of cortex.
Etheridge. A × 2; B × 3; C much enlarged.)
Blechnoxylon talbragarense, Etheridge. Fig. 343.
Under this name Etheridge[1336] described some specimens from the
Permo-Carboniferous Coal-Measures of New South Wales, which he
regards as a fern, comparable, in the possession of a cylinder of secondary
xylem, with the recent genus Botrychium and with Lyginodendron and other
members of the Cycadofilices. The slender axis (1–3 mm. in diameter)
appears to consist of a zone of radially disposed tissue (fig. 343, C, x),
which is probably of the nature of secondary xylem, enclosing a pith and
surrounded externally by imperfectly preserved remnants of cortex.
Page 556
Unfortunately no anatomical details could be made out, but the general
appearance, if not due to inorganic structure, certainly supports Etheridge’s
determination. The stem bore at intervals clusters of linear-lanceolate leaves
(reaching 12 mm. in length) in close spirals (fig. 343, A and B); the leaves
are characterised by a strong midrib and forked secondary veins. Small
“pyriform” bodies of the nature of scale-leaves occur in association with the
fronds (fig. 343, B, s).
In his description of this interesting plant, Etheridge quotes an opinion
which I expressed in regard to the comparison of the stem with those of
Botrychium, Lyginodendron, and other genera. No satisfactory evidence has
been found as to the nature of the fructification. Although the leaves of
Blechnoxylon are much smaller than those of Glossopteris, I am now
disposed to regard the genus as closely allied or even generically referable
to Glossopteris. The crowded disposition of the leaves is like that in
Glossopteris, shown in fig. 339 and in the figures published by Etheridge
and by Oldham; the association of scale-leaves and foliage-leaves is another
feature in common. The absence of a reticulum of anastomosing veins can
no longer be considered a fatal objection to the suggestion that the
Australian type may be a species of Glossopteris. If the view that
Blechnoxylon is not a distinct genus is correct, the occurrence of secondary
xylem is favourable to the opinion already expressed that Glossopteris is
more likely to be a Pteridosperm than a true fern. The data at present
available render it advisable to retain Mr Etheridge’s name: the comparison
with Glossopteris lacks confirmation.
BLECHNOXYLON
appearance, if not due to inorganic structure, certainly supports Etheridge’s
determination. The stem bore at intervals clusters of linear-lanceolate leaves
(reaching 12 mm. in length) in close spirals (fig. 343, A and B); the leaves
are characterised by a strong midrib and forked secondary veins. Small
“pyriform” bodies of the nature of scale-leaves occur in association with the
fronds (fig. 343, B, s).
In his description of this interesting plant, Etheridge quotes an opinion
which I expressed in regard to the comparison of the stem with those of
Botrychium, Lyginodendron, and other genera. No satisfactory evidence has
been found as to the nature of the fructification. Although the leaves of
Blechnoxylon are much smaller than those of Glossopteris, I am now
disposed to regard the genus as closely allied or even generically referable
to Glossopteris. The crowded disposition of the leaves is like that in
Glossopteris, shown in fig. 339 and in the figures published by Etheridge
and by Oldham; the association of scale-leaves and foliage-leaves is another
feature in common. The absence of a reticulum of anastomosing veins can
no longer be considered a fatal objection to the suggestion that the
Australian type may be a species of Glossopteris. If the view that
Blechnoxylon is not a distinct genus is correct, the occurrence of secondary
xylem is favourable to the opinion already expressed that Glossopteris is
more likely to be a Pteridosperm than a true fern. The data at present
available render it advisable to retain Mr Etheridge’s name: the comparison
with Glossopteris lacks confirmation.
BLECHNOXYLON
Page 557
Fig. 344. Glossopteris retifera. (Nat. size. From Arber, after Feistmantel.)
Glossopteris retifera, Feist. Fig. 344.
In some Glossopteris leaves the anastomosing secondary veins form a
coarser reticulum, as in the example represented in fig. 344. The name G.
retifera was given by Feistmantel[1337] to Indian fronds of this type; similar
forms have been described as G. conspicua and G. Tatei. The type
Glossopteris retifera, Feist. Fig. 344.
In some Glossopteris leaves the anastomosing secondary veins form a
coarser reticulum, as in the example represented in fig. 344. The name G.
retifera was given by Feistmantel[1337] to Indian fronds of this type; similar
forms have been described as G. conspicua and G. Tatei. The type
Page 558
illustrated by G. retifera is recorded also from Permo-Carboniferous rocks
in Zululand[1338], Natal, the Transvaal, Cape Colony, and the Argentine.
Gangamopteris.
In 1847 McCoy[1339] described a leaf-fragment from Permo-Carboniferous
rocks in New South Wales as Cyclopteris angustifolia. The type-specimen
of this species, which is now in the Sedgwick Museum, Cambridge, has
been re-described by Mr Arber[1340]. Subsequently[1341] McCoy instituted the
generic name Gangamopteris for leaves, like that previously referred by
him to Cyclopteris, from the Bacchus Marsh Sandstone, of New South
Wales, but he did not publish a diagnosis of the genus until several years
later[1342]. Feistmantel[1343], who has described many species of
Gangamopteris from the Lower Gondwana strata of India, slightly modified
the original diagnosis. The genus is represented by sterile fronds only. We
know nothing of the stem, and such evidence as is available in regard to the
form of the fertile leaves is of a circumstantial kind. It is, however, highly
probable that Gangamopteris is not a true fern but a Pteridosperm.
Leaves simple, sessile, varying in shape; obovate or spathulate, broadly lanceolate or rarely
linear; the apex is usually blunt (fig. 345) but occasionally gradually tapered. In general
appearance a Gangamopteris leaf is similar to that of Glossopteris indica, the chief distinction
being the absence of a midrib. Gangamopteris leaves are on the whole larger than those of
Glossopteris; many of them reach a length of 20 cm. and some of the large Indian fronds are
nearly 40 cm. long. The venation of Gangamopteris shows a greater uniformity in the size and
shape of the meshes than that of Glossopteris. The middle of the lamina, especially in the lower
part, is occupied by a few vertical veins from which branches curve upwards and outwards
towards the edge of the lamina. The secondary veins are connected by frequent anastomoses and
agree very closely with those of Glossopteris. The lamina becomes narrower towards the base,
which is either cuneate or in some cases slightly auriculate (fig. 345).
As I have elsewhere pointed out[1344], the presence or absence of a midrib
is not in itself a character of real taxonomic importance. In the recent fern
Scolopendrium vulgare the frond has a prominent midrib, while in S.
nigripes there is no median rib. Mr Arber has expressed the opinion that “it
is extremely doubtful whether the genus Gangamopteris should not be
merged in Glossopteris[1345].” The retention of the two names is, however,
convenient, and it would tend to confusion were we to carry to its logical
conclusion the view that the recognised distinction between the two genera
may not be a mark of generic difference.
in Zululand[1338], Natal, the Transvaal, Cape Colony, and the Argentine.
Gangamopteris.
In 1847 McCoy[1339] described a leaf-fragment from Permo-Carboniferous
rocks in New South Wales as Cyclopteris angustifolia. The type-specimen
of this species, which is now in the Sedgwick Museum, Cambridge, has
been re-described by Mr Arber[1340]. Subsequently[1341] McCoy instituted the
generic name Gangamopteris for leaves, like that previously referred by
him to Cyclopteris, from the Bacchus Marsh Sandstone, of New South
Wales, but he did not publish a diagnosis of the genus until several years
later[1342]. Feistmantel[1343], who has described many species of
Gangamopteris from the Lower Gondwana strata of India, slightly modified
the original diagnosis. The genus is represented by sterile fronds only. We
know nothing of the stem, and such evidence as is available in regard to the
form of the fertile leaves is of a circumstantial kind. It is, however, highly
probable that Gangamopteris is not a true fern but a Pteridosperm.
Leaves simple, sessile, varying in shape; obovate or spathulate, broadly lanceolate or rarely
linear; the apex is usually blunt (fig. 345) but occasionally gradually tapered. In general
appearance a Gangamopteris leaf is similar to that of Glossopteris indica, the chief distinction
being the absence of a midrib. Gangamopteris leaves are on the whole larger than those of
Glossopteris; many of them reach a length of 20 cm. and some of the large Indian fronds are
nearly 40 cm. long. The venation of Gangamopteris shows a greater uniformity in the size and
shape of the meshes than that of Glossopteris. The middle of the lamina, especially in the lower
part, is occupied by a few vertical veins from which branches curve upwards and outwards
towards the edge of the lamina. The secondary veins are connected by frequent anastomoses and
agree very closely with those of Glossopteris. The lamina becomes narrower towards the base,
which is either cuneate or in some cases slightly auriculate (fig. 345).
As I have elsewhere pointed out[1344], the presence or absence of a midrib
is not in itself a character of real taxonomic importance. In the recent fern
Scolopendrium vulgare the frond has a prominent midrib, while in S.
nigripes there is no median rib. Mr Arber has expressed the opinion that “it
is extremely doubtful whether the genus Gangamopteris should not be
merged in Glossopteris[1345].” The retention of the two names is, however,
convenient, and it would tend to confusion were we to carry to its logical
conclusion the view that the recognised distinction between the two genera
may not be a mark of generic difference.
Page 559
Gangamopteris is confined to Palaeozoic strata, a fact which leads
White[1346] to speak of the Gangamopteris rather than of the Glossopteris
Flora. It occurs in South America, South Africa, Australia, and India,
extending as far north as Kashmir; it has been discovered by Amalitzky in
Permian rocks of Russia[1347]. The Russian rocks in which Glossopteris and
Gangamopteris were found are no doubt of Permian age. In Australia,
South Africa, Brazil and Argentina, and in the Indian Coal-fields,
Gangamopteris is a characteristic genus of Lower Gondwana rocks. These
strata are usually spoken of as Permo-Carboniferous in order to avoid the
danger of attempting on insufficient data a precise correlation with
European formations.
Feistmantel speaks of Gangamopteris as most abundant in the Talchir-
Karharbári beds, though it is represented also in the overlying Damuda
series. In Australia the genus occurs in rocks which correspond in position
and in their plant fossils with the Talchir-Karharbári beds of India;
similarly, in South Africa and South America the Gangamopteris beds are
homotaxial with those of India and Australia. The leaf described by
Carruthers[1348] from Brazil as Noeggerathia obovata (the type-specimen is
in the British Museum) is no doubt specifically identical with
Gangamopteris cyclopteroides Feist.[1349] In a paper by Mr Hayden on
Gangamopteris beds in the Vihi Valley, Kashmir, evidence is adduced in
support of the conclusion that the rocks are “not younger than Upper
Carboniferous and may belong to the base of that subdivision or even to the
Middle Carboniferous[1350].” It would seem that Gangamopteris was a very
widely spread genus during the latter part of the Carboniferous period in the
vast Southern Continent to which the name Gondwana Land is often
applied, and that it flourished in the Southern Flora during at least part of
the Permian period: with other members of the Glossopteris Flora it
migrated to the North where it has been preserved in Permian rocks of
Northern Russia. The Glossopteris Flora must have had its birth in the
Southern hemisphere. The conclusion seems inevitable that the leaves of
Glossopteris and Gangamopteris in the shales and sandstones of India,
South Africa, South America, and Australia are relics of the vegetation of a
continent of which these regions are the disjuncta membra. Darwin wrote to
his friend Hooker in 1881, “I have sometimes speculated whether there did
not exist somewhere during long ages an extremely isolated continent,
White[1346] to speak of the Gangamopteris rather than of the Glossopteris
Flora. It occurs in South America, South Africa, Australia, and India,
extending as far north as Kashmir; it has been discovered by Amalitzky in
Permian rocks of Russia[1347]. The Russian rocks in which Glossopteris and
Gangamopteris were found are no doubt of Permian age. In Australia,
South Africa, Brazil and Argentina, and in the Indian Coal-fields,
Gangamopteris is a characteristic genus of Lower Gondwana rocks. These
strata are usually spoken of as Permo-Carboniferous in order to avoid the
danger of attempting on insufficient data a precise correlation with
European formations.
Feistmantel speaks of Gangamopteris as most abundant in the Talchir-
Karharbári beds, though it is represented also in the overlying Damuda
series. In Australia the genus occurs in rocks which correspond in position
and in their plant fossils with the Talchir-Karharbári beds of India;
similarly, in South Africa and South America the Gangamopteris beds are
homotaxial with those of India and Australia. The leaf described by
Carruthers[1348] from Brazil as Noeggerathia obovata (the type-specimen is
in the British Museum) is no doubt specifically identical with
Gangamopteris cyclopteroides Feist.[1349] In a paper by Mr Hayden on
Gangamopteris beds in the Vihi Valley, Kashmir, evidence is adduced in
support of the conclusion that the rocks are “not younger than Upper
Carboniferous and may belong to the base of that subdivision or even to the
Middle Carboniferous[1350].” It would seem that Gangamopteris was a very
widely spread genus during the latter part of the Carboniferous period in the
vast Southern Continent to which the name Gondwana Land is often
applied, and that it flourished in the Southern Flora during at least part of
the Permian period: with other members of the Glossopteris Flora it
migrated to the North where it has been preserved in Permian rocks of
Northern Russia. The Glossopteris Flora must have had its birth in the
Southern hemisphere. The conclusion seems inevitable that the leaves of
Glossopteris and Gangamopteris in the shales and sandstones of India,
South Africa, South America, and Australia are relics of the vegetation of a
continent of which these regions are the disjuncta membra. Darwin wrote to
his friend Hooker in 1881, “I have sometimes speculated whether there did
not exist somewhere during long ages an extremely isolated continent,
Page 560
perhaps near the South Pole[1351].” It is probable that Gangamopteris is one
of the genera which flourished on this continent.
Gangamopteris cyclopteroides, Feistmantel[1352]. Fig. 345.
1876. Feistmantel, Records Geol. Surv. India, Vol. ix. Pt iii. p. 73.
The specimen represented in fig. 345 illustrates the characters of this
commonest representative of the genus.
Fig. 345. Gangamopteris cyclopteroides, Feist. (Nat. size. From Arber, after Feistmantel.)
of the genera which flourished on this continent.
Gangamopteris cyclopteroides, Feistmantel[1352]. Fig. 345.
1876. Feistmantel, Records Geol. Surv. India, Vol. ix. Pt iii. p. 73.
The specimen represented in fig. 345 illustrates the characters of this
commonest representative of the genus.
Fig. 345. Gangamopteris cyclopteroides, Feist. (Nat. size. From Arber, after Feistmantel.)
Page 561
Gangamopteris kashmirensis, Seward.
1905. Seward, Mem. Geol. Surv. India, Vol. ii. Mem. ii.
This type agrees closely with G. cyclopteroides in size and in the form of
the leaf, but it is distinguished by the flatter form of the arch formed by the
lateral veins, by their greater inclination to the margin of the lamina, and by
the more acutely pointed apex of the lamina. This species, though not very
sharply distinguished from G. cyclopteroides, is important as coming from
beds which have been assigned on other than palaeobotanical evidence to
an Upper or possibly a Middle Carboniferous horizon[1353].
We have no definite information in regard to the nature of the
reproductive organs of Gangamopteris, but such evidence as there is
supports the view expressed by Dr White[1354] and shared by some other
authors that Gangamopteris and Glossopteris should be assigned to the
Pteridosperms. Despite the abundance of Gangamopteris leaves, no fertile
specimen has been discovered. This negative evidence may prove to be as
correct as that which led Stur[1355] to exclude Neuropteris, Alethopteris and
Odontopteris from the ferns. The only evidence of a positive kind is that
furnished by Dr David White in his recent Report on the Palaeozoic Flora
of South Brazil. This author describes some small Aphlebia-like leaves
under two new generic names Arberia[1356] and Derbyella[1357]. The
differences between the two sets of specimens, so far as can be determined
from the reproductions of imperfect impressions, are slight, and it is by no
means clear that a distinction of generic rank exists. These scale-leaves are
on the average about 2 cm. in length; the lamina is oval or rounded and has
more or less prominent lobes. In Derbyella there are indications of
anastomosing veins. The specimens referred to Arberia minasica are, as
White points out, very similar to the fossil described by Feistmantel from
Lower Gondwana rocks of India as probably a portion of an inflorescence
of Noeggerathiopsis[1358]. Feistmantel’s specimen is represented in fig. 346:
the curled lobes may have originally borne seeds. In the Brazilian examples
the abruptly truncated lobes “bear evidence of separation from reproductive
bodies.” An important point is the association of these scale-leaves with
Gangamopteris fronds and with gymnospermous seeds of the Samaropsis
type. On the leaves assigned to Derbyella aurita circular depressions occur
at the base of the lobes which are described as probably due to sporangia.
1905. Seward, Mem. Geol. Surv. India, Vol. ii. Mem. ii.
This type agrees closely with G. cyclopteroides in size and in the form of
the leaf, but it is distinguished by the flatter form of the arch formed by the
lateral veins, by their greater inclination to the margin of the lamina, and by
the more acutely pointed apex of the lamina. This species, though not very
sharply distinguished from G. cyclopteroides, is important as coming from
beds which have been assigned on other than palaeobotanical evidence to
an Upper or possibly a Middle Carboniferous horizon[1353].
We have no definite information in regard to the nature of the
reproductive organs of Gangamopteris, but such evidence as there is
supports the view expressed by Dr White[1354] and shared by some other
authors that Gangamopteris and Glossopteris should be assigned to the
Pteridosperms. Despite the abundance of Gangamopteris leaves, no fertile
specimen has been discovered. This negative evidence may prove to be as
correct as that which led Stur[1355] to exclude Neuropteris, Alethopteris and
Odontopteris from the ferns. The only evidence of a positive kind is that
furnished by Dr David White in his recent Report on the Palaeozoic Flora
of South Brazil. This author describes some small Aphlebia-like leaves
under two new generic names Arberia[1356] and Derbyella[1357]. The
differences between the two sets of specimens, so far as can be determined
from the reproductions of imperfect impressions, are slight, and it is by no
means clear that a distinction of generic rank exists. These scale-leaves are
on the average about 2 cm. in length; the lamina is oval or rounded and has
more or less prominent lobes. In Derbyella there are indications of
anastomosing veins. The specimens referred to Arberia minasica are, as
White points out, very similar to the fossil described by Feistmantel from
Lower Gondwana rocks of India as probably a portion of an inflorescence
of Noeggerathiopsis[1358]. Feistmantel’s specimen is represented in fig. 346:
the curled lobes may have originally borne seeds. In the Brazilian examples
the abruptly truncated lobes “bear evidence of separation from reproductive
bodies.” An important point is the association of these scale-leaves with
Gangamopteris fronds and with gymnospermous seeds of the Samaropsis
type. On the leaves assigned to Derbyella aurita circular depressions occur
at the base of the lobes which are described as probably due to sporangia.
Page 562
Dr White’s discovery gives us increased confidence in expressing the
view that Gangamopteris bore its reproductive organs on specialised leaves
very different from the sterile fronds; it also strengthens the suspicion that
the genus is a member of the class of seed-bearing fern-like plants.
Fig. 346. Arberia sp. (= Noeggerathiopsis of Feistmantel). (Nat. size. After Feistmantel.)
Lesleya.
This generic designation was instituted by Lesquereux[1359] for simple
oval-linear leaves from the Coal-Measures of Pennsylvania. The leaves so
named are probably generically identical with the specimen doubtfully
assigned by Brongniart[1360] to the Coal-Measures, and made by him the type
of the genus Cannophyllites on the ground of a resemblance to the leaves of
the recent flowering plant Canna. Fig. 347 illustrates the form of a Lesleya
leaf from the Coal-basin of Gard, named by Grand’Eury L.
simplicinervis[1361], a type in which the veins are frequently unbranched and
not repeatedly forked as in most examples of the genus (fig. 329, C). The
features of the genus are, the oval-linear or lanceolate shape of the
presumably simple frond, its entire or, in one species at least (L. Delafondi,
Zeill.), finely dentate margin, the stout rachis giving off at a very acute
angle numerous dichotomously branched secondary veins. In L. Delafondi
(fig. 329, C), described by Zeiller[1362] from the Lower Permian of Autun,
the frond may reach a length of more than 20 cm. and a breadth of 8 cm.
Similar species are represented by L. ensis[1363] from the coal-field of
Commentry, and L. grandis[1364] from Upper Carboniferous rocks of North
view that Gangamopteris bore its reproductive organs on specialised leaves
very different from the sterile fronds; it also strengthens the suspicion that
the genus is a member of the class of seed-bearing fern-like plants.
Fig. 346. Arberia sp. (= Noeggerathiopsis of Feistmantel). (Nat. size. After Feistmantel.)
Lesleya.
This generic designation was instituted by Lesquereux[1359] for simple
oval-linear leaves from the Coal-Measures of Pennsylvania. The leaves so
named are probably generically identical with the specimen doubtfully
assigned by Brongniart[1360] to the Coal-Measures, and made by him the type
of the genus Cannophyllites on the ground of a resemblance to the leaves of
the recent flowering plant Canna. Fig. 347 illustrates the form of a Lesleya
leaf from the Coal-basin of Gard, named by Grand’Eury L.
simplicinervis[1361], a type in which the veins are frequently unbranched and
not repeatedly forked as in most examples of the genus (fig. 329, C). The
features of the genus are, the oval-linear or lanceolate shape of the
presumably simple frond, its entire or, in one species at least (L. Delafondi,
Zeill.), finely dentate margin, the stout rachis giving off at a very acute
angle numerous dichotomously branched secondary veins. In L. Delafondi
(fig. 329, C), described by Zeiller[1362] from the Lower Permian of Autun,
the frond may reach a length of more than 20 cm. and a breadth of 8 cm.
Similar species are represented by L. ensis[1363] from the coal-field of
Commentry, and L. grandis[1364] from Upper Carboniferous rocks of North
Page 563
America. The genus is characteristic of Upper Carboniferous and Lower
Permian strata: the form of the leaf and the direction of the secondary veins
suggest comparison with Glossopteris, but in Lesleya there are no cross-
connexions between the veins. Nothing is known as to the fructification, a
fact which naturally evokes the opinion that the genus is a Pteridosperm[1365]
and not a true fern. Some years before the discovery of Pteridosperms,
Grand’Eury[1366] suggested that Lesleya might be a Gymnosperm; his
opinion being based on the woody nature of the rachis and on the simple
venation of Lesleya simplicinervis.
Fig. 347. Leslya simplicinervis, Grand’Eury. (Reduced: after Grand’Eury.)
Neuropteridium.
Permian strata: the form of the leaf and the direction of the secondary veins
suggest comparison with Glossopteris, but in Lesleya there are no cross-
connexions between the veins. Nothing is known as to the fructification, a
fact which naturally evokes the opinion that the genus is a Pteridosperm[1365]
and not a true fern. Some years before the discovery of Pteridosperms,
Grand’Eury[1366] suggested that Lesleya might be a Gymnosperm; his
opinion being based on the woody nature of the rachis and on the simple
venation of Lesleya simplicinervis.
Fig. 347. Leslya simplicinervis, Grand’Eury. (Reduced: after Grand’Eury.)
Neuropteridium.
Page 564
In their monograph of fossil plants from the Bunter Series of the Vosges,
Schimper and Mougeot[1367] described some pinnate leaves of ferns as
species of the genus Neuropteris. In 1869 Schimper[1368] placed these in a
new sub-genus Neuropteridium, in order to draw attention to the fact that
their fronds appear to be simply pinnate and not bipinnate or tripinnate as in
Neuropteris. The type-species of Neuropteridium is N. grandifolia Sch. and
Moug. from the Bunter Sandstones of the Vosges. The genus includes
Triassic European species and the widely distributed Permo-Carboniferous
species from Brazil[1369] originally described by Carruthers as Odontopteris
Plantiana. It is probable that some Carboniferous plants, particularly
species from the lower members of the formation, referred to the genus
Cardiopteris, are not genetically distinct from the Indian and southern
hemisphere type Neuropteridium validum (= Odontopteris Plantiana).
Fronds pinnate, linear; a broad rachis bears pinnules which may be either semicircular or
broadly linear with an entire or lobed margin. The longer pinnules may exceed 6 cm. in length.
The pinnules agree with those of Neuropteris in being attached by the median portion of the
lamina and not by the whole base, which is more or less auriculate. In some cases the repeatedly
forked veins diverge from the centre of the pinnule base; in others there is a midrib which
persists for a short distance only, and in some species the more persistent median vein gives the
segments a closer resemblance to those of Neuropteris. Fructification unknown, with the
exception of obscure indications of sporangia (?) on the fertile leaves of a Triassic species.
Schimper and Mougeot[1367] described some pinnate leaves of ferns as
species of the genus Neuropteris. In 1869 Schimper[1368] placed these in a
new sub-genus Neuropteridium, in order to draw attention to the fact that
their fronds appear to be simply pinnate and not bipinnate or tripinnate as in
Neuropteris. The type-species of Neuropteridium is N. grandifolia Sch. and
Moug. from the Bunter Sandstones of the Vosges. The genus includes
Triassic European species and the widely distributed Permo-Carboniferous
species from Brazil[1369] originally described by Carruthers as Odontopteris
Plantiana. It is probable that some Carboniferous plants, particularly
species from the lower members of the formation, referred to the genus
Cardiopteris, are not genetically distinct from the Indian and southern
hemisphere type Neuropteridium validum (= Odontopteris Plantiana).
Fronds pinnate, linear; a broad rachis bears pinnules which may be either semicircular or
broadly linear with an entire or lobed margin. The longer pinnules may exceed 6 cm. in length.
The pinnules agree with those of Neuropteris in being attached by the median portion of the
lamina and not by the whole base, which is more or less auriculate. In some cases the repeatedly
forked veins diverge from the centre of the pinnule base; in others there is a midrib which
persists for a short distance only, and in some species the more persistent median vein gives the
segments a closer resemblance to those of Neuropteris. Fructification unknown, with the
exception of obscure indications of sporangia (?) on the fertile leaves of a Triassic species.
Page 565
Fig. 348. Neuropteridium validum, Feist. Nat. size. From the Karharbári Coal-field, India.
From Arber, after Feistmantel.
Neuropteridium validum. (Feistmantel[1370]). Fig. 348.
1869. Odontopteris Plantiana, Carruthers, Geol. Mag. Vol. vi. p. 9,
Pl. vi. figs. 2, 3.
1878. Neuropteris valida, Feistmantel, Mem. Geol. Surv. India,
Foss. Flor. Gondwana Syst., Vol. iii. p. 10, pl. ii.–vi.
1880. Neuropteridium validum, Feistmantel, Ibid. 2, p. 84.
From Arber, after Feistmantel.
Neuropteridium validum. (Feistmantel[1370]). Fig. 348.
1869. Odontopteris Plantiana, Carruthers, Geol. Mag. Vol. vi. p. 9,
Pl. vi. figs. 2, 3.
1878. Neuropteris valida, Feistmantel, Mem. Geol. Surv. India,
Foss. Flor. Gondwana Syst., Vol. iii. p. 10, pl. ii.–vi.
1880. Neuropteridium validum, Feistmantel, Ibid. 2, p. 84.
Page 566
The specimen represented in fig. 348 illustrates the main features of
Neuropteridium validum. This species is referred to by Dr White[1371] as N.
Plantianum on the ground of priority, and with a view to perpetuate the
name of the English engineer Nathaniel Plant who discovered the species in
a Brazilian Coal-field in the province of Rio Grande do Sul. Feistmantel’s
specific name is however retained as being much better known. An
examination of Mr Plant’s specimen in the British Museum led me[1372] to
speak of the Brazilian species as identical with N. validum described by
Feistmantel from Lower Gondwana rocks of India. Zeiller[1373] had
previously drawn attention to the resemblance between the two sets of
specimens. The frond of N. validum may exceed 50 cm. in length. The
lower pinnules may be entire and semicircular in form while the upper and
larger segments, which may reach a length of 5 or 6 cm., are characterised
by broad lobes (fig. 348).
This type is represented in the flora of the Talchir-Karharbári series
(Lower Gondwana) of India[1374], in Permo-Carboniferous rocks of Brazil
and Argentine[1375], and in the sandstones of Vereeniging on the borders of
the Transvaal and Cape Colony. It is a characteristic member of the
Glossopteris Flora and occurs in association with Glossopteris and
Gangamopteris.
Neuropteridium intermedium (Schimper). Fig. 349.
This species has been figured by Schimper and Mougeot[1376] from the
Bunter of the Vosges and more fully described by Blanckenhorn[1377] from
the Bunter beds of Commern. The pinnate leaves reach a length of 65 cm.;
the lower semicircular pinnules pass gradually into broadly linear segments
characterised by an auriculate base and a Neuropteris type of venation (fig.
354, D′, E). In the example reproduced in fig. 349 from one of
Blanckenhorn’s figures, the fronds are attached to a short and thick rhizome
bearing roots and portions of old petioles.
Neuropteridium validum. This species is referred to by Dr White[1371] as N.
Plantianum on the ground of priority, and with a view to perpetuate the
name of the English engineer Nathaniel Plant who discovered the species in
a Brazilian Coal-field in the province of Rio Grande do Sul. Feistmantel’s
specific name is however retained as being much better known. An
examination of Mr Plant’s specimen in the British Museum led me[1372] to
speak of the Brazilian species as identical with N. validum described by
Feistmantel from Lower Gondwana rocks of India. Zeiller[1373] had
previously drawn attention to the resemblance between the two sets of
specimens. The frond of N. validum may exceed 50 cm. in length. The
lower pinnules may be entire and semicircular in form while the upper and
larger segments, which may reach a length of 5 or 6 cm., are characterised
by broad lobes (fig. 348).
This type is represented in the flora of the Talchir-Karharbári series
(Lower Gondwana) of India[1374], in Permo-Carboniferous rocks of Brazil
and Argentine[1375], and in the sandstones of Vereeniging on the borders of
the Transvaal and Cape Colony. It is a characteristic member of the
Glossopteris Flora and occurs in association with Glossopteris and
Gangamopteris.
Neuropteridium intermedium (Schimper). Fig. 349.
This species has been figured by Schimper and Mougeot[1376] from the
Bunter of the Vosges and more fully described by Blanckenhorn[1377] from
the Bunter beds of Commern. The pinnate leaves reach a length of 65 cm.;
the lower semicircular pinnules pass gradually into broadly linear segments
characterised by an auriculate base and a Neuropteris type of venation (fig.
354, D′, E). In the example reproduced in fig. 349 from one of
Blanckenhorn’s figures, the fronds are attached to a short and thick rhizome
bearing roots and portions of old petioles.
Page 567
Fig. 349. Neuropteridium intermedium (Schimp.). (After Blanckenhorn. ¼ nat. size.)
An example of another Triassic species is afforded by Neuropteridium
grandifolium Schimp. and Moug., which agrees very closely with N.
validum in the size and shape of the pinnules. The occurrence in Lower
Mesozoic European rocks of fronds hardly distinguishable from the older
southern species may be regarded as favourable to the view already
expressed, that some at least of the Permo-Carboniferous plants migrated
north of the Equator. The resemblance between the Vosges Triassic species
of Schizoneura[1378] and the examples of this genus recorded from the Lower
An example of another Triassic species is afforded by Neuropteridium
grandifolium Schimp. and Moug., which agrees very closely with N.
validum in the size and shape of the pinnules. The occurrence in Lower
Mesozoic European rocks of fronds hardly distinguishable from the older
southern species may be regarded as favourable to the view already
expressed, that some at least of the Permo-Carboniferous plants migrated
north of the Equator. The resemblance between the Vosges Triassic species
of Schizoneura[1378] and the examples of this genus recorded from the Lower
Page 568
Gondwana rocks of India affords additional evidence of a northern
migration.
Our knowledge of the reproductive organs of Neuropteridium is
practically nil. There is no doubt that Zeiller[1379] and Blanckenhorn[1380] are
correct in regarding the Bunter fronds assigned by Schimper and Mougeot
to the genus Crematopteris as the fertile leaves of Neuropteridium
intermedium or some other species from the same horizon. These fronds
bear crowded pinnules similar to those of Neuropteridium intermedium, N.
Voltzii[1381], and other species, exhibiting on the exposed surface numerous
carbonaceous spots which may be the remains of sporangia.
Cardiopteris.
Schimper[1382] applied this generic name to Lower Carboniferous fronds
of a simple-pinnate habit which had previously been described as species of
Cyclopteris. Cardiopteris frondosa may serve as a typical example. This
species, originally described by Goeppert as Cyclopteris frondosa (fig.
350), is recorded from Lower Carboniferous rocks in the Vosges district[1383]
in Silesia, Moravia[1384], and Thuringia[1385]. The pinnules, which are attached
in opposite pairs to a broad rachis, vary in length from 2 to 10 cm. and have
a breadth of 2 to 8 cm.; in manner of attachment and venation they agree
with those of Neuropteridium validum. The venation is very clearly shown
in a drawing of some large pinnules figured by Stur[1386].
The specimen of Cardiopteris frondosa, a portion of which is shown in
fig. 350 on a slightly reduced scale, was originally figured by Schimper
from an unusually good example in the Strassburg Museum. Schimper’s
drawing hardly does justice to the original specimen.
A frond bearing rather narrower pinnules, alternately placed on the
rachis, which Fritsch has described as Cardiopteris Hochstetterii var.
franconica from the Culm of Thuringia, bears a close resemblance to
Neuropteridium validum but differs in the entire margin of the pinnules. An
Upper Carboniferous species from Russia described by Grigoriew[1387] as
Neuropteris, cf. cordata var. densineura, represents another form of similar
habit.
migration.
Our knowledge of the reproductive organs of Neuropteridium is
practically nil. There is no doubt that Zeiller[1379] and Blanckenhorn[1380] are
correct in regarding the Bunter fronds assigned by Schimper and Mougeot
to the genus Crematopteris as the fertile leaves of Neuropteridium
intermedium or some other species from the same horizon. These fronds
bear crowded pinnules similar to those of Neuropteridium intermedium, N.
Voltzii[1381], and other species, exhibiting on the exposed surface numerous
carbonaceous spots which may be the remains of sporangia.
Cardiopteris.
Schimper[1382] applied this generic name to Lower Carboniferous fronds
of a simple-pinnate habit which had previously been described as species of
Cyclopteris. Cardiopteris frondosa may serve as a typical example. This
species, originally described by Goeppert as Cyclopteris frondosa (fig.
350), is recorded from Lower Carboniferous rocks in the Vosges district[1383]
in Silesia, Moravia[1384], and Thuringia[1385]. The pinnules, which are attached
in opposite pairs to a broad rachis, vary in length from 2 to 10 cm. and have
a breadth of 2 to 8 cm.; in manner of attachment and venation they agree
with those of Neuropteridium validum. The venation is very clearly shown
in a drawing of some large pinnules figured by Stur[1386].
The specimen of Cardiopteris frondosa, a portion of which is shown in
fig. 350 on a slightly reduced scale, was originally figured by Schimper
from an unusually good example in the Strassburg Museum. Schimper’s
drawing hardly does justice to the original specimen.
A frond bearing rather narrower pinnules, alternately placed on the
rachis, which Fritsch has described as Cardiopteris Hochstetterii var.
franconica from the Culm of Thuringia, bears a close resemblance to
Neuropteridium validum but differs in the entire margin of the pinnules. An
Upper Carboniferous species from Russia described by Grigoriew[1387] as
Neuropteris, cf. cordata var. densineura, represents another form of similar
habit.
Page 569
Fig. 350. Cardiopteris frondosa (Goepp.). (¾ nat. size. After Schimper.)
Schuster[1388] has recently proposed a new generic name Ulvopteris for a
fragment of a pinna from the Coal-Measures of Dudweiler in Germany
bearing large pinnules, which he compares with those of Cardiopteris and
species of Rhacopteris. The specimen appears to be indistinguishable from
some of those already referred to as conforming to Neuropteridium, and it is
difficult to recognise any reason for the creation of a new generic name.
We cannot hope to arrive at any satisfactory decision in regard to the
precise affinity between Neuropteridium validum and species referred to
Cardiopteris and other genera so long as portions of sterile fronds are the
only tests at our disposal. It is difficult to determine whether a specimen
consisting of an axis bearing pinnules represents a large pinna of a bipinnate
frond or if it is a complete pinnate leaf. There is, however, no adequate
reason for supposing that the presumably pinnate fronds from the
Gondwana Land rocks are generically distinct from the Lower
Carboniferous European species Cardiopteris frondosa. Granting the
probability that both genera are Pteridosperms and closely allied to one
Schuster[1388] has recently proposed a new generic name Ulvopteris for a
fragment of a pinna from the Coal-Measures of Dudweiler in Germany
bearing large pinnules, which he compares with those of Cardiopteris and
species of Rhacopteris. The specimen appears to be indistinguishable from
some of those already referred to as conforming to Neuropteridium, and it is
difficult to recognise any reason for the creation of a new generic name.
We cannot hope to arrive at any satisfactory decision in regard to the
precise affinity between Neuropteridium validum and species referred to
Cardiopteris and other genera so long as portions of sterile fronds are the
only tests at our disposal. It is difficult to determine whether a specimen
consisting of an axis bearing pinnules represents a large pinna of a bipinnate
frond or if it is a complete pinnate leaf. There is, however, no adequate
reason for supposing that the presumably pinnate fronds from the
Gondwana Land rocks are generically distinct from the Lower
Carboniferous European species Cardiopteris frondosa. Granting the
probability that both genera are Pteridosperms and closely allied to one
Page 570
another, the two generic names may be retained on the ground of long usage
and in default of satisfactory evidence confirmatory of generic identity.
Cardiopteris would thus stand for a type of frond characteristic of the
Lower Carboniferous strata of Europe, while Neuropteridium is retained for
the Southern species N. validum, and for others from the Trias of the
Vosges.
Aphlebia.
This name was proposed by Presl[1389] for large leaf-like impressions
having a pinnate or pinnatifid form and characterised by a confused
irregular type of venation, or by a fine superficial striation or wrinkling
which simulates veins. Gutbier had previously described similar fossils as
Fucoides, and other authors have described Aphlebiae as species of
Rhacophyllum, Schizopteris, and other genera[1390]. The term Aphlebia is
retained, not as denoting a distinct genus but (i) as a descriptive name for
detached leafy structures similar to those figured by Presl, which are now
recognised as laminar appendages of the petioles of ferns or fern-like
fronds, and (ii) as an epithet for highly modified pinnules which frequently
occur at the base of the primary pinnae of Pecopteroid and Sphenopteroid
fronds (e.g. Dactylotheca plumosa, fig. 293)[1391].
Modified pinnules, similar in their reduced and deeply dissected lamina
to those represented in fig. 293, are frequently found at the base of the
primary pinnae of Palaeozoic species of Sphenopteris and other genera of
Pteridosperms or ferns, including members of the Coenopterideae.
Potonié[1392] gives a list of various types of Aphlebiae in his paper on these
organs. A striking case has recently been described by Zeiller in a French
Upper Carboniferous species, Sphenopteris Matheti[1393]. It would seem that
the larger examples of Aphlebiae are more frequently associated with the
compound leaves of Pteridosperms than with those of Ferns[1394].
As examples of the larger types of Aphlebiae reference may be made to
Aphlebia crispa (Gutb.)[1395], which reaches a length of nearly 60 cm. and
has the form of a more or less triangular pinnate leaf divided into decurrent
deeply lobed segments, to a similar species represented by A. Germari (=
Schizopteris lactuca Germ.)[1396] which simulates the leaves of endive
and in default of satisfactory evidence confirmatory of generic identity.
Cardiopteris would thus stand for a type of frond characteristic of the
Lower Carboniferous strata of Europe, while Neuropteridium is retained for
the Southern species N. validum, and for others from the Trias of the
Vosges.
Aphlebia.
This name was proposed by Presl[1389] for large leaf-like impressions
having a pinnate or pinnatifid form and characterised by a confused
irregular type of venation, or by a fine superficial striation or wrinkling
which simulates veins. Gutbier had previously described similar fossils as
Fucoides, and other authors have described Aphlebiae as species of
Rhacophyllum, Schizopteris, and other genera[1390]. The term Aphlebia is
retained, not as denoting a distinct genus but (i) as a descriptive name for
detached leafy structures similar to those figured by Presl, which are now
recognised as laminar appendages of the petioles of ferns or fern-like
fronds, and (ii) as an epithet for highly modified pinnules which frequently
occur at the base of the primary pinnae of Pecopteroid and Sphenopteroid
fronds (e.g. Dactylotheca plumosa, fig. 293)[1391].
Modified pinnules, similar in their reduced and deeply dissected lamina
to those represented in fig. 293, are frequently found at the base of the
primary pinnae of Palaeozoic species of Sphenopteris and other genera of
Pteridosperms or ferns, including members of the Coenopterideae.
Potonié[1392] gives a list of various types of Aphlebiae in his paper on these
organs. A striking case has recently been described by Zeiller in a French
Upper Carboniferous species, Sphenopteris Matheti[1393]. It would seem that
the larger examples of Aphlebiae are more frequently associated with the
compound leaves of Pteridosperms than with those of Ferns[1394].
As examples of the larger types of Aphlebiae reference may be made to
Aphlebia crispa (Gutb.)[1395], which reaches a length of nearly 60 cm. and
has the form of a more or less triangular pinnate leaf divided into decurrent
deeply lobed segments, to a similar species represented by A. Germari (=
Schizopteris lactuca Germ.)[1396] which simulates the leaves of endive
Page 571
(Cichorium endivia L.), and to some large forms figured by Grand’Eury[1397]
as species of Schizopteris.
Aphlebiae such as that figured by Kidston[1398] as Rhacophyllum crispum,
with narrow ultimate segments, might easily be mistaken for the
impressions of an alga.
The term Aphlebia may be applied also to the Cyclopteroid pinnules on
the petioles of some species of Neuropteris, Odontopteris and
Archaeopteris. Goebel[1399] has referred to the application by Potonié and
other authors of the term Aphlebioid to the pinnules which serve as bud-
protecting organs in recent fronds of Gleichenia (fig. 226, p. 290); he
expresses the opinion that it is superfluous and misleading to make use of a
special designation for structures which are undoubtedly modified pinnules.
In the case of fossils it is, however, convenient to employ the term Aphlebia
as a descriptive name for modified pinnules or stipular structures which
cannot be connected with definite species of fronds. It is clear that some
Aphlebiod leaflets, such as those of Dactylotheca, served as protective
organs for the unexpanded pinnae[1400], and in all probability the large
Aphlebiae served the same purpose as the fleshy stipules of Angiopteris and
Marattia which cover the uncoiled fronds. The pinnatifid scale-leaves of
considerable size (fig. 351) which occur in the leaf-axils or as ochrea-like
stipules on the fronds of Gunnera (a tropical and subtropical
Dicotyledonous genus) bear a very close resemblance to some Palaeozoic
Aphlebiae, e.g. Aphlebia crispa (Gutb.). The recent and fossil scale-leaves
may be regarded as similar in function as in form; moreover the delicate
coiled fronds of Palaeozoic Pteridosperms or ferns, like those of some
recent flowering plants, may have been kept moist by a secretion of
mucilage. The pinnatifid stipules of Marattia fraxinea (fig. 241, B, p. 317)
resemble certain fossil Aphlebiae, and the wrinkled surface of the recent
stipules presents an appearance similar to that which in some fossil forms
has been erroneously described as veining. It is not improbable that mantle-
leaves of such recent ferns as Polypodium quercifolium (fig. 234, M, p. 303)
are comparable with some fossil Aphlebiae which may have served as
humus-collectors for Palaeozoic epiphytes.
as species of Schizopteris.
Aphlebiae such as that figured by Kidston[1398] as Rhacophyllum crispum,
with narrow ultimate segments, might easily be mistaken for the
impressions of an alga.
The term Aphlebia may be applied also to the Cyclopteroid pinnules on
the petioles of some species of Neuropteris, Odontopteris and
Archaeopteris. Goebel[1399] has referred to the application by Potonié and
other authors of the term Aphlebioid to the pinnules which serve as bud-
protecting organs in recent fronds of Gleichenia (fig. 226, p. 290); he
expresses the opinion that it is superfluous and misleading to make use of a
special designation for structures which are undoubtedly modified pinnules.
In the case of fossils it is, however, convenient to employ the term Aphlebia
as a descriptive name for modified pinnules or stipular structures which
cannot be connected with definite species of fronds. It is clear that some
Aphlebiod leaflets, such as those of Dactylotheca, served as protective
organs for the unexpanded pinnae[1400], and in all probability the large
Aphlebiae served the same purpose as the fleshy stipules of Angiopteris and
Marattia which cover the uncoiled fronds. The pinnatifid scale-leaves of
considerable size (fig. 351) which occur in the leaf-axils or as ochrea-like
stipules on the fronds of Gunnera (a tropical and subtropical
Dicotyledonous genus) bear a very close resemblance to some Palaeozoic
Aphlebiae, e.g. Aphlebia crispa (Gutb.). The recent and fossil scale-leaves
may be regarded as similar in function as in form; moreover the delicate
coiled fronds of Palaeozoic Pteridosperms or ferns, like those of some
recent flowering plants, may have been kept moist by a secretion of
mucilage. The pinnatifid stipules of Marattia fraxinea (fig. 241, B, p. 317)
resemble certain fossil Aphlebiae, and the wrinkled surface of the recent
stipules presents an appearance similar to that which in some fossil forms
has been erroneously described as veining. It is not improbable that mantle-
leaves of such recent ferns as Polypodium quercifolium (fig. 234, M, p. 303)
are comparable with some fossil Aphlebiae which may have served as
humus-collectors for Palaeozoic epiphytes.
Page 572
Fig. 351. Scale-leaf of Gunnera manicata. (Slightly reduced. M.S.)
The filiform appendages on the petioles of the recent fern Hemitelia
capensis (fig. 235, p. 304) have often been compared with the aphlebioid
leaflets of fossil fronds.
Potonié who has discussed the nature of Aphlebiae regards them as
vestiges of a once continuous lamina, which formed a winged border to the
branched axes of more primitive forms of fronds. It is possible that the
pinnules between the pinnae on the rachis of Archaeopteris and the
Cyclopteroid leaflets of Neuropteris and Odontopteris may have the
morphological significance attributed to them by Potonié. In some cases it
The filiform appendages on the petioles of the recent fern Hemitelia
capensis (fig. 235, p. 304) have often been compared with the aphlebioid
leaflets of fossil fronds.
Potonié who has discussed the nature of Aphlebiae regards them as
vestiges of a once continuous lamina, which formed a winged border to the
branched axes of more primitive forms of fronds. It is possible that the
pinnules between the pinnae on the rachis of Archaeopteris and the
Cyclopteroid leaflets of Neuropteris and Odontopteris may have the
morphological significance attributed to them by Potonié. In some cases it
Page 573
is probable that the Aphlebiae, whether vestiges or not, served the purpose
of protecting either the whole frond or individual pinnae. Aphlebiae, though
especially characteristic of Palaeozoic leaves, are occasionally met with in
the form of modified pinnules at the base of the primary pinnae on
Mesozoic ferns, e.g. in Coniopteris hymenophylloides[1401].
In some fern fronds the lowest pinnule of each pinna differs in shape or
size from the normal ultimate segments, but it would be almost affectation
to extend the use of the term Aphlebia to such pinnules. The Jurassic
species Cladophlebis lobifolia (Phill.) is a case in point[1402]. In this fern,
which some authors speak of, without sufficient reason, as Dicksonia
lobifolia[1403], the lowest pinnule is large and different in shape from the
others.
of protecting either the whole frond or individual pinnae. Aphlebiae, though
especially characteristic of Palaeozoic leaves, are occasionally met with in
the form of modified pinnules at the base of the primary pinnae on
Mesozoic ferns, e.g. in Coniopteris hymenophylloides[1401].
In some fern fronds the lowest pinnule of each pinna differs in shape or
size from the normal ultimate segments, but it would be almost affectation
to extend the use of the term Aphlebia to such pinnules. The Jurassic
species Cladophlebis lobifolia (Phill.) is a case in point[1402]. In this fern,
which some authors speak of, without sufficient reason, as Dicksonia
lobifolia[1403], the lowest pinnule is large and different in shape from the
others.
Page 574
Fig. 352.
A. Sphenopteris obtusiloba. Pinnule. (Enlarged. After Zeiller.)
B, C. S. obtusiloba. (⅞ nat. size. After Zeiller.)
D. Pecopteris arborescens. (Slightly enlarged. After Zeiller.)
E. Sphenopteris furcata (= Diplotmema furcatum). (Slightly enlarged. After Zeiller.)
Sphenopteris.
Sphenopteris is one of the many generic names which we owe to
Brongniart[1404]. It is the generic designation used for a great number of
Palaeozoic and later fronds, most of which are those of true ferns while
some Palaeozoic species are undoubted Pteridosperms. The genus, which is
purely provisional, includes members of widely different families
possessing pinnules of the same general type, such as is represented in some
recent species of Davallia, Asplenium, and other ferns.
A. Sphenopteris obtusiloba. Pinnule. (Enlarged. After Zeiller.)
B, C. S. obtusiloba. (⅞ nat. size. After Zeiller.)
D. Pecopteris arborescens. (Slightly enlarged. After Zeiller.)
E. Sphenopteris furcata (= Diplotmema furcatum). (Slightly enlarged. After Zeiller.)
Sphenopteris.
Sphenopteris is one of the many generic names which we owe to
Brongniart[1404]. It is the generic designation used for a great number of
Palaeozoic and later fronds, most of which are those of true ferns while
some Palaeozoic species are undoubted Pteridosperms. The genus, which is
purely provisional, includes members of widely different families
possessing pinnules of the same general type, such as is represented in some
recent species of Davallia, Asplenium, and other ferns.
Page 575
The fronds of Sphenopteris may be bipinnate, tripinnate, or quadripinnate; the rachis may be
dichotomously branched or the branching may be of the pinnate type characteristic of most
recent ferns. The pinnules are small; they vary considerably in shape even in a single frond, but
the chief characteristics are: the lobed lamina, contracted and often wedge-shaped at the base
(fig. 352), the dichotomously branched veins radiating from the base or given off from a median
rib at an acute angle. The lamina may be divided into a few bluntly rounded lobes (fig. 352, C) or
deeply dissected into linear or cuneate segments (fig. 352, A, B, E).
Examples of Sphenopteroid leaves have already been described under the
genera Coniopteris, Onychiopsis, Ruffordia, etc. Among the numerous
examples of Sphenopteris species from the Carboniferous rocks mention
may be made of Sphenopteris obtusiloba Brogn.[1405] (fig. 352, A–C), which
occurs in the Middle and Lower Coal-Measures of Britain[1406]. This type is
characterised by the almost orbicular, oval or triangular pinnules which may
reach a length of 15 mm.; they are occasionally entire, but more usually
divided into 3 to 5 rounded lobes. The forked veins radiate from the base of
the pinnule. The rachis may be dichotomously branched. Fructification
unknown.
The species S. furcata Brongn.[1407], characteristic of the Middle and
Lower Coal-Measures of Britain (fig. 352, E), is referred to under Stur’s
genus Diplotmema[1408] in which it is included by some authors solely
because of the dichotomous habit of branching of the pinnae.
The pinna represented in fig. 353 illustrates a similar type of pinnule.
This species, which is very common in the Calciferous Sandstone of
Scotland, was described by Lindley and Hutton as Sphenopteris affinis[1409].
The fronds of Sphenopteris affinis were discovered by Mr Peach[1410] in a
fertile condition, but he regarded the reproductive organs as those of a plant
parasitic on the Sphenopteris fronds. Kidston[1411] substituted Stur’s genus
Calymmatotheca for Sphenopteris on the ground that the sporangia figured
by Peach under the name Staphylopteris Peachii bear a close resemblance
to the organs which Stur described as valves of an indusium in his species
Calymmatotheca Stangeri[1412]. An examination of Stur’s specimens by Miss
Benson[1413] and by Prof. Oliver and Dr Scott has confirmed Stur’s
interpretation of the appendages at the tips of the fertile pinnae as valves of
an indusial or cupular structure. The superficially similar bodies on the
fertile pinnae of S. affinis are however true sporangia, and cannot
legitimately be included in the genus Calymmatotheca as described by Stur.
For this reason Miss Benson institutes a new genus Telangium, the type-
dichotomously branched or the branching may be of the pinnate type characteristic of most
recent ferns. The pinnules are small; they vary considerably in shape even in a single frond, but
the chief characteristics are: the lobed lamina, contracted and often wedge-shaped at the base
(fig. 352), the dichotomously branched veins radiating from the base or given off from a median
rib at an acute angle. The lamina may be divided into a few bluntly rounded lobes (fig. 352, C) or
deeply dissected into linear or cuneate segments (fig. 352, A, B, E).
Examples of Sphenopteroid leaves have already been described under the
genera Coniopteris, Onychiopsis, Ruffordia, etc. Among the numerous
examples of Sphenopteris species from the Carboniferous rocks mention
may be made of Sphenopteris obtusiloba Brogn.[1405] (fig. 352, A–C), which
occurs in the Middle and Lower Coal-Measures of Britain[1406]. This type is
characterised by the almost orbicular, oval or triangular pinnules which may
reach a length of 15 mm.; they are occasionally entire, but more usually
divided into 3 to 5 rounded lobes. The forked veins radiate from the base of
the pinnule. The rachis may be dichotomously branched. Fructification
unknown.
The species S. furcata Brongn.[1407], characteristic of the Middle and
Lower Coal-Measures of Britain (fig. 352, E), is referred to under Stur’s
genus Diplotmema[1408] in which it is included by some authors solely
because of the dichotomous habit of branching of the pinnae.
The pinna represented in fig. 353 illustrates a similar type of pinnule.
This species, which is very common in the Calciferous Sandstone of
Scotland, was described by Lindley and Hutton as Sphenopteris affinis[1409].
The fronds of Sphenopteris affinis were discovered by Mr Peach[1410] in a
fertile condition, but he regarded the reproductive organs as those of a plant
parasitic on the Sphenopteris fronds. Kidston[1411] substituted Stur’s genus
Calymmatotheca for Sphenopteris on the ground that the sporangia figured
by Peach under the name Staphylopteris Peachii bear a close resemblance
to the organs which Stur described as valves of an indusium in his species
Calymmatotheca Stangeri[1412]. An examination of Stur’s specimens by Miss
Benson[1413] and by Prof. Oliver and Dr Scott has confirmed Stur’s
interpretation of the appendages at the tips of the fertile pinnae as valves of
an indusial or cupular structure. The superficially similar bodies on the
fertile pinnae of S. affinis are however true sporangia, and cannot
legitimately be included in the genus Calymmatotheca as described by Stur.
For this reason Miss Benson institutes a new genus Telangium, the type-
Page 576
species of which, T. Scotti from the Lower Coal-Measures of Lancashire, is
based on petrified material. The Scotch species Sphenopteris affinis (=
Calymmatotheca affinis of Kidston) is also transferred to Telangium; the
sporangia are considered by Miss Benson to be microsporangia. This with
other species is no doubt correctly included in the Pteridosperms. A
complete frond of Sphenopteris affinis, showing a regular dichotomy of the
main axes, is represented by an admirable drawing in Hugh Miller’s
Testimony of the Rocks[1414].
Fig. 353. Sphenopteris affinis, Lind. and Hutt. From the Calciferous Sandstone of
Burdiehouse (Scotland). (Sedgwick Museum, Cambridge.) M.S.
based on petrified material. The Scotch species Sphenopteris affinis (=
Calymmatotheca affinis of Kidston) is also transferred to Telangium; the
sporangia are considered by Miss Benson to be microsporangia. This with
other species is no doubt correctly included in the Pteridosperms. A
complete frond of Sphenopteris affinis, showing a regular dichotomy of the
main axes, is represented by an admirable drawing in Hugh Miller’s
Testimony of the Rocks[1414].
Fig. 353. Sphenopteris affinis, Lind. and Hutt. From the Calciferous Sandstone of
Burdiehouse (Scotland). (Sedgwick Museum, Cambridge.) M.S.
Page 577
Some of the Palaeozoic species of Sphenopteris probably represent the
fronds of true ferns, but others are known to have been borne by
Pteridosperms. S. Hoeninghausi (fig. 290, C, p. 399) is the foliage of
Lyginodendron, and Scott[1415] speaks of three species, S. dissecta, S.
elegans, and S. Linkii as the leaves of Heterangium. Grand’Eury[1416] has
recorded the occurrence in French Coal-Measures of seeds in association
with other Sphenopteroid fronds.
Mariopteris, Diplotmema, Palmatopteris.
The discovery of sporangia on the fronds of several Palaeozoic species of
Sphenopteris and Pecopteris has led to the institution of new generic
names, which indicate an advance in knowledge beyond the stage implied
by the use of those provisional designations based solely on the form and
venation of the pinnules. Other names have been created by authors in place
of Sphenopteris and Pecopteris on the ground that a striking feature in the
mode of branching of fronds is sufficiently important to justify generic
recognition even in the absence of fertile specimens. As examples of
designations based primarily on the branch-system of compound leaves, the
genera Mariopteris, Diplotmema, and Palmatopteris may be briefly
considered (fig. 354 A–C). Dr Kidston[1417] is of opinion that the creation of
new genera for purely vegetative characters of fronds is of no real
advantage, and he prefers to retain the older provisional names for species
known only in the sterile condition. On the other hand, if we are sufficiently
familiar with specimens large enough to enable us to recognise a well-
defined morphological character, it may serve a useful purpose to employ a
generic designation for features which may have a phylogenetic value. A
comparative examination of Palaeozoic, Mesozoic, and recent compound
fronds, including both Pteridosperms and true ferns, brings to light certain
distinguishing features characteristic of the older types which, as Potonié
maintains[1418], point to the derivation of the pinnate habit from a primitive
dichotomous system of branching. For a more complete discussion of this
question reference should be made to Potonié’s suggestive papers. Among
recent ferns Matonia and Dipteris, two survivals from the past, afford
instances of fronds with a branching system of the dichotomous type.
Similarly, in Gleichenia, Lygodium, and more rarely in species of
Polypodiaceae (e.g. Davallia aculeata, fig. 232) dichotomy is a striking
fronds of true ferns, but others are known to have been borne by
Pteridosperms. S. Hoeninghausi (fig. 290, C, p. 399) is the foliage of
Lyginodendron, and Scott[1415] speaks of three species, S. dissecta, S.
elegans, and S. Linkii as the leaves of Heterangium. Grand’Eury[1416] has
recorded the occurrence in French Coal-Measures of seeds in association
with other Sphenopteroid fronds.
Mariopteris, Diplotmema, Palmatopteris.
The discovery of sporangia on the fronds of several Palaeozoic species of
Sphenopteris and Pecopteris has led to the institution of new generic
names, which indicate an advance in knowledge beyond the stage implied
by the use of those provisional designations based solely on the form and
venation of the pinnules. Other names have been created by authors in place
of Sphenopteris and Pecopteris on the ground that a striking feature in the
mode of branching of fronds is sufficiently important to justify generic
recognition even in the absence of fertile specimens. As examples of
designations based primarily on the branch-system of compound leaves, the
genera Mariopteris, Diplotmema, and Palmatopteris may be briefly
considered (fig. 354 A–C). Dr Kidston[1417] is of opinion that the creation of
new genera for purely vegetative characters of fronds is of no real
advantage, and he prefers to retain the older provisional names for species
known only in the sterile condition. On the other hand, if we are sufficiently
familiar with specimens large enough to enable us to recognise a well-
defined morphological character, it may serve a useful purpose to employ a
generic designation for features which may have a phylogenetic value. A
comparative examination of Palaeozoic, Mesozoic, and recent compound
fronds, including both Pteridosperms and true ferns, brings to light certain
distinguishing features characteristic of the older types which, as Potonié
maintains[1418], point to the derivation of the pinnate habit from a primitive
dichotomous system of branching. For a more complete discussion of this
question reference should be made to Potonié’s suggestive papers. Among
recent ferns Matonia and Dipteris, two survivals from the past, afford
instances of fronds with a branching system of the dichotomous type.
Similarly, in Gleichenia, Lygodium, and more rarely in species of
Polypodiaceae (e.g. Davallia aculeata, fig. 232) dichotomy is a striking
Page 578
feature of the fronds. In the great majority of recent ferns the fronds have
assumed a pinnate habit. Among Palaeozoic fern-like fronds dichotomous
branching of the main rachis and of the pinnae is much more common.
Potonié draws attention to several other features which distinguish
Palaeozoic fronds from the majority of later species: the frequent
occurrence of pinnules borne directly on the main rachis (fig. 354, D), and
of modified pinnules or Aphlebiae on the rachis and petiole, are characters
to which he attributes an evolutionary significance. The main point is that a
comparative examination of leaf-form affords evidence in favour of the
view that the modern type of frond, with its naked rachis bearing two rows
of pinnae, has been derived from a less specialised type in which the
distinction between the parts of the leaf is much less evident. The primitive
leaf was probably a dichotomously branched axis provided with a
continuous lamina which eventually became broken up into separate lobes
or pinnules.
As the dichotomy of the frond became less regular, a pinnate habit was
acquired, as is clearly seen in many Palaeozoic types which constitute
connecting links between forked and pinnate fronds (fig. 354, D). The
Aphlebiae may be remnants of the once-continuous lamina on the petiole,
and the normal pinnules borne on the rachis may be regarded as the
attributes of fronds in which the division of physiological labour had not
reached the stage which characterises the leaves of recent ferns.
Mariopteris.
This name, which is due to Zeiller[1419], is applied by him to Palaeozoic
fronds characterised by a double bifurcation of the rachis of the primary
pinnae. Mariopteris muricata (= Pecopteris muricata Schloth.) may be
taken as the type of the genus. This species is common in the Lower and
Middle Coal-Measures of Britain and rare in the Upper Coal-Measures[1420].
It is described by Kidston[1421] as one of the most polymorphic and widely
distributed Coal-Measure species. The pinnules as seen in fig. 364, B, are of
the Sphenopteroid type. No fertile specimens are known, but it is significant
that Grand’Eury[1422] has recorded the association of Mariopteris muricata
and seeds.
The main rachis gives off alternate naked branches, each of which
bifurcates at its apex into two short naked axes, and these are again forked,
assumed a pinnate habit. Among Palaeozoic fern-like fronds dichotomous
branching of the main rachis and of the pinnae is much more common.
Potonié draws attention to several other features which distinguish
Palaeozoic fronds from the majority of later species: the frequent
occurrence of pinnules borne directly on the main rachis (fig. 354, D), and
of modified pinnules or Aphlebiae on the rachis and petiole, are characters
to which he attributes an evolutionary significance. The main point is that a
comparative examination of leaf-form affords evidence in favour of the
view that the modern type of frond, with its naked rachis bearing two rows
of pinnae, has been derived from a less specialised type in which the
distinction between the parts of the leaf is much less evident. The primitive
leaf was probably a dichotomously branched axis provided with a
continuous lamina which eventually became broken up into separate lobes
or pinnules.
As the dichotomy of the frond became less regular, a pinnate habit was
acquired, as is clearly seen in many Palaeozoic types which constitute
connecting links between forked and pinnate fronds (fig. 354, D). The
Aphlebiae may be remnants of the once-continuous lamina on the petiole,
and the normal pinnules borne on the rachis may be regarded as the
attributes of fronds in which the division of physiological labour had not
reached the stage which characterises the leaves of recent ferns.
Mariopteris.
This name, which is due to Zeiller[1419], is applied by him to Palaeozoic
fronds characterised by a double bifurcation of the rachis of the primary
pinnae. Mariopteris muricata (= Pecopteris muricata Schloth.) may be
taken as the type of the genus. This species is common in the Lower and
Middle Coal-Measures of Britain and rare in the Upper Coal-Measures[1420].
It is described by Kidston[1421] as one of the most polymorphic and widely
distributed Coal-Measure species. The pinnules as seen in fig. 364, B, are of
the Sphenopteroid type. No fertile specimens are known, but it is significant
that Grand’Eury[1422] has recorded the association of Mariopteris muricata
and seeds.
The main rachis gives off alternate naked branches, each of which
bifurcates at its apex into two short naked axes, and these are again forked,
Page 579
the ultimate branches having the form of bipinnate pinnae provided with
large Sphenopteroid pinnules (fig. 354, B). Zeiller includes in Mariopteris
some species which Stur[1423] referred to his genus Diplotmema. Possibly
some of the Palaeozoic fronds with a zigzag rachis may have been climbers
like Lygodium.
large Sphenopteroid pinnules (fig. 354, B). Zeiller includes in Mariopteris
some species which Stur[1423] referred to his genus Diplotmema. Possibly
some of the Palaeozoic fronds with a zigzag rachis may have been climbers
like Lygodium.
Page 580
Fig. 354.
A. Palmatopteris.
B. Mariopteris. (A, B, after Potonié.)
C. Diplotmema Zeilleri, Stur. (After Zeiller.)
C′. D. Zeilleri. Pinnule. (× 3. After Zeiller.)
D. Neuropteris macrophylla. (British Museum.)
D′. N. macrophylla. Pinnule. (Slightly enlarged. After Kidston.)
E. N. heterophylla. Pinnule. (Slightly enlarged. After Zeiller.)
F. N. Scheuchzeri. (Slightly reduced. After Kidston.)
G. Alloiopteris Essinghii. (Enlarged. After Potonié.)
Diplotmema.
A. Palmatopteris.
B. Mariopteris. (A, B, after Potonié.)
C. Diplotmema Zeilleri, Stur. (After Zeiller.)
C′. D. Zeilleri. Pinnule. (× 3. After Zeiller.)
D. Neuropteris macrophylla. (British Museum.)
D′. N. macrophylla. Pinnule. (Slightly enlarged. After Kidston.)
E. N. heterophylla. Pinnule. (Slightly enlarged. After Zeiller.)
F. N. Scheuchzeri. (Slightly reduced. After Kidston.)
G. Alloiopteris Essinghii. (Enlarged. After Potonié.)
Diplotmema.
Page 581
This generic name is employed by Zeiller[1424] and other authors in a more
restricted sense than that in which it was originally used by Stur. The Upper
Carboniferous species Sphenopteris furcata Brongn. (fig. 352, E) may serve
as the type. This species occurs in the Middle and Lower Coal-Measures of
Britain[1425]. The main rachis gives off branches as in Mariopteris, but in
Diplotmema each naked lateral branch is forked at its apex into two
opposite pinnae bearing deeply dissected Sphenopteroid pinnules.
Zeiller[1426] and Stur have recorded fertile specimens of Diplotmema, but in
no case have actual sporangia been discovered. In the species Diplotmema
Zeilleri Stur (fig. 354, C, C′) two Aphlebiae occur at the base of each
secondary axis[1427]. It has been pointed out by Potonié that in Diplotmema
furcatum the equal dichotomy of the lateral branches is not characteristic of
the frond as a whole. In the case of branches higher on the rachis the
dichotomy becomes unequal and the forked axis is gradually replaced by a
simple pinna (fig. 354, A). For this type of frond, Potonié proposed the
generic name Palmatopteris in place of Diplotmema, which he discards.
The long comparatively slender rachis of P. furcata suggests comparison
with the liane species of Lygodium[1428].
restricted sense than that in which it was originally used by Stur. The Upper
Carboniferous species Sphenopteris furcata Brongn. (fig. 352, E) may serve
as the type. This species occurs in the Middle and Lower Coal-Measures of
Britain[1425]. The main rachis gives off branches as in Mariopteris, but in
Diplotmema each naked lateral branch is forked at its apex into two
opposite pinnae bearing deeply dissected Sphenopteroid pinnules.
Zeiller[1426] and Stur have recorded fertile specimens of Diplotmema, but in
no case have actual sporangia been discovered. In the species Diplotmema
Zeilleri Stur (fig. 354, C, C′) two Aphlebiae occur at the base of each
secondary axis[1427]. It has been pointed out by Potonié that in Diplotmema
furcatum the equal dichotomy of the lateral branches is not characteristic of
the frond as a whole. In the case of branches higher on the rachis the
dichotomy becomes unequal and the forked axis is gradually replaced by a
simple pinna (fig. 354, A). For this type of frond, Potonié proposed the
generic name Palmatopteris in place of Diplotmema, which he discards.
The long comparatively slender rachis of P. furcata suggests comparison
with the liane species of Lygodium[1428].
Page 582
Fig. 355.
A. Cephalotheca mirabilis, Nath. Fertile pinnae. (Partially restored. After Nathorst.)
B. C. mirabilis. Sterile pinnule. Nat. size. (After Nathorst.)
Cephalotheca.
This genus was proposed by Nathorst[1429] for some peculiar bipinnate
fertile fronds from the Upper Devonian rocks of Bear Island. The pinnae
bear slender forked ultimate segments represented by a few detached
fragments (fig. 355, B), associated with the rachises. The fertile pinnae are
given off in opposite pairs from the main axis over which they are
A. Cephalotheca mirabilis, Nath. Fertile pinnae. (Partially restored. After Nathorst.)
B. C. mirabilis. Sterile pinnule. Nat. size. (After Nathorst.)
Cephalotheca.
This genus was proposed by Nathorst[1429] for some peculiar bipinnate
fertile fronds from the Upper Devonian rocks of Bear Island. The pinnae
bear slender forked ultimate segments represented by a few detached
fragments (fig. 355, B), associated with the rachises. The fertile pinnae are
given off in opposite pairs from the main axis over which they are
Page 583
concrescent (fig. 355, A). A mop-like cluster of sporangia is borne on the
lower surface and close to the base of a fertile pinna: the exannulate
sporangia are compared with those of Scolecopteris. Nathorst compares
Cephalotheca with a Belgian species of Upper Devonian age described by
Crépin[1430] as Rhacophyton condrusorum and by Gilkinet[1431] as
Sphenopteris condrusorum. A similar fossil is also described by Baily[1432] as
Filicites lineatus from the Kitorkan Grits of Ireland.
The position of Cephalotheca cannot be definitely determined from the
available data, but it is more probable that it was a seed-bearing
Pteridosperm and not a true fern. Zeiller[1433] has recently expressed the
same opinion.
Thinnfeldia.
The genus Thinnfeldia, founded by Ettingshausen in 1852[1434] on some
Hungarian Liassic specimens, though frequently included in the Filicales,
cannot be said to occupy that position by virtue of any well-authenticated
filicinean features. It is by no means improbable that many of the species
referred to this genus are closely allied to Palaeozoic Pteridosperms.
Thinnfeldia may be briefly defined as follows:
Fronds simple and pinnatifid, pinnate or bipinnate: rachis broad and occasionally
dichotomously branched. Pinnules often fleshy or coriaceous; broadly linear, entire or lobed,
provided with a midrib from which simple or forked secondary veins are given off at an acute
angle: or the laminae may be short and broad without a midrib and traversed by several slightly
divergent and forked veins.
No satisfactory evidence of reproductive organs has so far been adduced.
The genus is chiefly characteristic of Upper Triassic, Rhaetic, and
Jurassic floras, though it was in all probability represented in Permian
floras. Several species, many of which are valueless, are recorded also from
Cretaceous and Tertiary formations. Search should be made for fertile
specimens or for evidence as to the association of seeds with Thinnfeldia
fronds.
Some Permian fossils from Kansas which Sellards[1435] has made the type
of a new genus, Glenopteris, appear to be indistinguishable generically
lower surface and close to the base of a fertile pinna: the exannulate
sporangia are compared with those of Scolecopteris. Nathorst compares
Cephalotheca with a Belgian species of Upper Devonian age described by
Crépin[1430] as Rhacophyton condrusorum and by Gilkinet[1431] as
Sphenopteris condrusorum. A similar fossil is also described by Baily[1432] as
Filicites lineatus from the Kitorkan Grits of Ireland.
The position of Cephalotheca cannot be definitely determined from the
available data, but it is more probable that it was a seed-bearing
Pteridosperm and not a true fern. Zeiller[1433] has recently expressed the
same opinion.
Thinnfeldia.
The genus Thinnfeldia, founded by Ettingshausen in 1852[1434] on some
Hungarian Liassic specimens, though frequently included in the Filicales,
cannot be said to occupy that position by virtue of any well-authenticated
filicinean features. It is by no means improbable that many of the species
referred to this genus are closely allied to Palaeozoic Pteridosperms.
Thinnfeldia may be briefly defined as follows:
Fronds simple and pinnatifid, pinnate or bipinnate: rachis broad and occasionally
dichotomously branched. Pinnules often fleshy or coriaceous; broadly linear, entire or lobed,
provided with a midrib from which simple or forked secondary veins are given off at an acute
angle: or the laminae may be short and broad without a midrib and traversed by several slightly
divergent and forked veins.
No satisfactory evidence of reproductive organs has so far been adduced.
The genus is chiefly characteristic of Upper Triassic, Rhaetic, and
Jurassic floras, though it was in all probability represented in Permian
floras. Several species, many of which are valueless, are recorded also from
Cretaceous and Tertiary formations. Search should be made for fertile
specimens or for evidence as to the association of seeds with Thinnfeldia
fronds.
Some Permian fossils from Kansas which Sellards[1435] has made the type
of a new genus, Glenopteris, appear to be indistinguishable generically
Page 584
from leaves of Lower Mesozoic age universally recognised as typical
examples of Thinnfeldia.
Thinnfeldia odontopteroides (Morris)[1436]. Figs. 356–358.
This is a very variable species as regards the shape and size of the
ultimate segments and their venation. It is a type of extended geographical
range characteristic of Rhaetic or Upper Triassic rocks in Australia, South
Africa, India, South America, and various European localities.
Frond bipinnate; the broad rachis may be dichotomously branched. Pinnules with a thick
lamina which may be almost semicircular in form, deltoid, broadly oval or broadly linear, and
often confluent at the base. Short and broad pinnules occur on some fronds directly attached to
the main rachis between the pinnae. The longer and narrower pinnules (fig. 356, C), resembling
those of the Palaeozoic genus Alethopteris, have a well-defined midrib, while the smaller
segments are characterised by several slightly divergent veins which spring directly from the
rachis (fig. 356, A). Epidermal cells polygonal or, above the veins, rectangular in shape; stomata,
which are slightly sunk, occur on both the upper and lower epidermis. Fertile specimens
unknown.
The portion of a lobed pinnule shown in fig. 356, B, illustrates a form of
segment intermediate between the linear type with a midrib and a row of
shorter pinnules without a median vein. Fig. 356, D, represents another
instance of variation in the arrangement of the veins in segments of
different sizes. Various specific and generic names have been assigned to
Thinnfeldia fronds of Rhaetic age on the ground of the occurrence of
pinnules longer and narrower than those usually associated with T.
odontopteroides; but in view of the range of variation met with in a single
leaf it is advisable to extend rather than to restrict the boundary of what we
are pleased to regard as a specific type.
examples of Thinnfeldia.
Thinnfeldia odontopteroides (Morris)[1436]. Figs. 356–358.
This is a very variable species as regards the shape and size of the
ultimate segments and their venation. It is a type of extended geographical
range characteristic of Rhaetic or Upper Triassic rocks in Australia, South
Africa, India, South America, and various European localities.
Frond bipinnate; the broad rachis may be dichotomously branched. Pinnules with a thick
lamina which may be almost semicircular in form, deltoid, broadly oval or broadly linear, and
often confluent at the base. Short and broad pinnules occur on some fronds directly attached to
the main rachis between the pinnae. The longer and narrower pinnules (fig. 356, C), resembling
those of the Palaeozoic genus Alethopteris, have a well-defined midrib, while the smaller
segments are characterised by several slightly divergent veins which spring directly from the
rachis (fig. 356, A). Epidermal cells polygonal or, above the veins, rectangular in shape; stomata,
which are slightly sunk, occur on both the upper and lower epidermis. Fertile specimens
unknown.
The portion of a lobed pinnule shown in fig. 356, B, illustrates a form of
segment intermediate between the linear type with a midrib and a row of
shorter pinnules without a median vein. Fig. 356, D, represents another
instance of variation in the arrangement of the veins in segments of
different sizes. Various specific and generic names have been assigned to
Thinnfeldia fronds of Rhaetic age on the ground of the occurrence of
pinnules longer and narrower than those usually associated with T.
odontopteroides; but in view of the range of variation met with in a single
leaf it is advisable to extend rather than to restrict the boundary of what we
are pleased to regard as a specific type.
Page 585
Fig. 356.
A–D. Thinnfeldia odontopteroides (Morris).
E. Ptilozamites. (E, after Nathorst.)
The name Thinnfeldia lancifolia has been applied by Morris to fossils
from Australia which may be identified with T. odontopteroides, and the
same designation is employed by Szajnocha and by Solms-Laubach[1437] for
Rhaetic specimens from South America. Similar fronds are described by
Geinitz[1438] as Thinnfeldia tenuinervis from Argentine Rhaetic strata.
Odontopteris macrophylla Curran, T. falcata Ten.-Woods, Gleichenia
lineata Ten.-Woods, and Cardiopteris Zuberi Szaj. afford other examples of
what are probably closely allied forms[1439].
A–D. Thinnfeldia odontopteroides (Morris).
E. Ptilozamites. (E, after Nathorst.)
The name Thinnfeldia lancifolia has been applied by Morris to fossils
from Australia which may be identified with T. odontopteroides, and the
same designation is employed by Szajnocha and by Solms-Laubach[1437] for
Rhaetic specimens from South America. Similar fronds are described by
Geinitz[1438] as Thinnfeldia tenuinervis from Argentine Rhaetic strata.
Odontopteris macrophylla Curran, T. falcata Ten.-Woods, Gleichenia
lineata Ten.-Woods, and Cardiopteris Zuberi Szaj. afford other examples of
what are probably closely allied forms[1439].
Page 586
Fig. 357. Thinnfeldia odontopteroides (Morris). ⅘ nat. size.
Some exceptionally large examples of T. odontopteroides are figured by
Feistmantel[1440] from the Hawkesbury series of New South Wales in which
the bipinnate frond has a breadth of 25–30 cm. A specimen from the
Molteno beds of South Africa, probably of Rhaetic age, represented in fig.
357, illustrates a smaller leaf with pinnules of the linear type, some of
which are partially divided into shorter pinnules with forked veins. The
example represented in fig. 358, from Cyphergat (S. Africa), shows two
equal branches of a rachis with small contiguous segments.
Some exceptionally large examples of T. odontopteroides are figured by
Feistmantel[1440] from the Hawkesbury series of New South Wales in which
the bipinnate frond has a breadth of 25–30 cm. A specimen from the
Molteno beds of South Africa, probably of Rhaetic age, represented in fig.
357, illustrates a smaller leaf with pinnules of the linear type, some of
which are partially divided into shorter pinnules with forked veins. The
example represented in fig. 358, from Cyphergat (S. Africa), shows two
equal branches of a rachis with small contiguous segments.
Page 587
Fig. 358. Thinnfeldia odontopteroides. From a specimen in the British Museum (v. 2490). 1½
nat. size.
Some specimens figured by Zeiller[1441] from the Rhaetic strata of Tonkin
as Pecopteris (Bernouillia?) sp. may be portions of Thinnfeldia fronds, and
the large leaves which he refers to Ctenopteris Sarreni differ but slightly
from the Australian specimens described by Feistmantel as T.
odontopteroides.
Thinnfeldia rhomboidalis, Ettingshausen. Figs. 359, 360, C.
Under this name Ettingshausen described the type-specimen of the genus
from Lower Lias strata at Steierdorf in Hungary. He assigned the plant to
the Coniferae on the ground of a resemblance of the pinnules to the
phylloclades of Phyllocladus. Thinnfeldia rhomboidalis bears a close
resemblance to T. odontopteroides, but the pinnules are usually longer and
nat. size.
Some specimens figured by Zeiller[1441] from the Rhaetic strata of Tonkin
as Pecopteris (Bernouillia?) sp. may be portions of Thinnfeldia fronds, and
the large leaves which he refers to Ctenopteris Sarreni differ but slightly
from the Australian specimens described by Feistmantel as T.
odontopteroides.
Thinnfeldia rhomboidalis, Ettingshausen. Figs. 359, 360, C.
Under this name Ettingshausen described the type-specimen of the genus
from Lower Lias strata at Steierdorf in Hungary. He assigned the plant to
the Coniferae on the ground of a resemblance of the pinnules to the
phylloclades of Phyllocladus. Thinnfeldia rhomboidalis bears a close
resemblance to T. odontopteroides, but the pinnules are usually longer and
Page 588
narrower, as shown in the English specimen from the Lower Lias of
Dorsetshire represented in fig. 359. The darker margin of the pinnules
shown in fig. 360, C, gives the impression of a revolute lamina, but a
microscopical examination points to a thicker cuticle at the edge of the
segments.
Fig. 359. Thinnfeldia rhomboidalis, Ettings. Slightly reduced. From an English Liassic
specimen in the British Museum. [M.S.]
The species is recorded from Jurassic rocks of France, Germany, Italy,
India, Australia, and elsewhere[1442].
Palaeobotanical literature contains numerous records of Jurassic,
Cretaceous and some Tertiary species referred to Thinnfeldia, but many of
these are probably not generically identical with T. odontopteroides or T.
rhomboidalis. Mr Berry[1443] in a paper on The American species referred to
Thinnfeldia concludes that the genus is “a rather indefinite one ... and badly
in need of revision.” He regards the Middle and Upper Cretaceous
American species as Conifers related to Phyllocladus and probably forming
Dorsetshire represented in fig. 359. The darker margin of the pinnules
shown in fig. 360, C, gives the impression of a revolute lamina, but a
microscopical examination points to a thicker cuticle at the edge of the
segments.
Fig. 359. Thinnfeldia rhomboidalis, Ettings. Slightly reduced. From an English Liassic
specimen in the British Museum. [M.S.]
The species is recorded from Jurassic rocks of France, Germany, Italy,
India, Australia, and elsewhere[1442].
Palaeobotanical literature contains numerous records of Jurassic,
Cretaceous and some Tertiary species referred to Thinnfeldia, but many of
these are probably not generically identical with T. odontopteroides or T.
rhomboidalis. Mr Berry[1443] in a paper on The American species referred to
Thinnfeldia concludes that the genus is “a rather indefinite one ... and badly
in need of revision.” He regards the Middle and Upper Cretaceous
American species as Conifers related to Phyllocladus and probably forming
Page 589
a link between the Podocarpeae and Taxeae: for these forms he proposes the
generic name Protophyllocladus. The opinion has been expressed
elsewhere[1444] that this “problematical[1445]” genus rests on an unsatisfactory
basis; the available data do not justify the use of a name which implies the
existence in North American Cretaceous floras of a type related to the New
Zealand and Tasmanian Conifer Phyllocladus. We are not in a position to
assign a single species of Thinnfeldia to the Filicales or the Gymnosperms.
A leaflet from Jurassic rocks of Poland figured by Raciborski[1446] shows
what this author regards as the impression of a circular sorus: no sporangia
have been found. A specimen in the British Museum[1447], which is said to
come from Rhaetic beds in Queensland, shows a row of contiguous
polygonal prominences on each side of the midrib which resemble the sori
of a fern; but until sporangia are discovered we cannot determine the
precise nature of this apparently fertile frond.
A species described by Fontaine[1448] from the Potomac beds (Wealden-
Jurassic) of North America as Thinnfeldia variabilis affords a good example
of a plant which cannot be identified with any degree of confidence either
as a fern or a seed-bearing type. Mr Berry draws attention to the former
application of this name by Velenovský to a distinct Lower Cretaceous
Bohemian species and proposes for Fontaine’s plant the name T. Fontainei;
he maintains that no one has doubted the fern-nature of the Potomac plant.
T. variabilis may indeed be a fern, but the evidence is not such as to
preclude legitimate doubts as to the correctness of this suggestion. Solms-
Laubach[1449], in referring to Schenk’s view that Thinnfeldia and its allies
may represent a group intermediate between Ferns and Gymnosperms,
admits that it is a possible supposition; he is, however, inclined to consider
Lomatopteris and Cycadopteris, “genera especially comparable with
Thinnfeldia” as more probably ferns.
At this point we may conveniently consider a series of genera which
occupy an equally uncertain position and bear a very close resemblance to
Thinnfeldia.
generic name Protophyllocladus. The opinion has been expressed
elsewhere[1444] that this “problematical[1445]” genus rests on an unsatisfactory
basis; the available data do not justify the use of a name which implies the
existence in North American Cretaceous floras of a type related to the New
Zealand and Tasmanian Conifer Phyllocladus. We are not in a position to
assign a single species of Thinnfeldia to the Filicales or the Gymnosperms.
A leaflet from Jurassic rocks of Poland figured by Raciborski[1446] shows
what this author regards as the impression of a circular sorus: no sporangia
have been found. A specimen in the British Museum[1447], which is said to
come from Rhaetic beds in Queensland, shows a row of contiguous
polygonal prominences on each side of the midrib which resemble the sori
of a fern; but until sporangia are discovered we cannot determine the
precise nature of this apparently fertile frond.
A species described by Fontaine[1448] from the Potomac beds (Wealden-
Jurassic) of North America as Thinnfeldia variabilis affords a good example
of a plant which cannot be identified with any degree of confidence either
as a fern or a seed-bearing type. Mr Berry draws attention to the former
application of this name by Velenovský to a distinct Lower Cretaceous
Bohemian species and proposes for Fontaine’s plant the name T. Fontainei;
he maintains that no one has doubted the fern-nature of the Potomac plant.
T. variabilis may indeed be a fern, but the evidence is not such as to
preclude legitimate doubts as to the correctness of this suggestion. Solms-
Laubach[1449], in referring to Schenk’s view that Thinnfeldia and its allies
may represent a group intermediate between Ferns and Gymnosperms,
admits that it is a possible supposition; he is, however, inclined to consider
Lomatopteris and Cycadopteris, “genera especially comparable with
Thinnfeldia” as more probably ferns.
At this point we may conveniently consider a series of genera which
occupy an equally uncertain position and bear a very close resemblance to
Thinnfeldia.
Page 590
Fig. 360.
A. Lomatopteris jurensis. (⅞ nat. size. After Kurr.)
B. L. Schimperi. (⅞ nat. size. After Salfeld.)
C. Thinnfeldia rhomboidalis, Ett. (Slightly enlarged. British Museum. No. 52672.)
Lomatopteris.
The generic name Lomatopteris was proposed by Schimper[1450] for some
bipinnate fronds originally described by Kurr[1451] from Jurassic rocks of
Württemberg as Odontopteris (?) jurensis (fig. 360, A). I have elsewhere
expressed the opinion[1452] that this German species may be identical with
Thinnfeldia rhomboidalis Ett. Kurr’s type-specimen, a portion of which is
reproduced in fig. 360, A, consists of a frond or large pinna characterised by
a prominent and broad rachis giving off alternate linear pinnae bearing
bluntly rounded, contiguous and basally concrescent pinnules having a
thick or revolute border and a central rib. The lateral veins are visible in the
ultimate segments of Kurr’s fossil. Saporta[1453] has described several
species, which he refers to Schimper’s genus, from French Jurassic strata: it
is, however, difficult to recognise some of the examples represented in his
illustrations as specifically distinct forms. This author notices the
resemblance of Lomatopteris to Thinnfeldia, not only in habit but in the
structure of the epidermal cells[1454]. In Lomatopteris and in Thinnfeldia the
cells have straight and not sinuous walls and the slightly sunken stomata are
A. Lomatopteris jurensis. (⅞ nat. size. After Kurr.)
B. L. Schimperi. (⅞ nat. size. After Salfeld.)
C. Thinnfeldia rhomboidalis, Ett. (Slightly enlarged. British Museum. No. 52672.)
Lomatopteris.
The generic name Lomatopteris was proposed by Schimper[1450] for some
bipinnate fronds originally described by Kurr[1451] from Jurassic rocks of
Württemberg as Odontopteris (?) jurensis (fig. 360, A). I have elsewhere
expressed the opinion[1452] that this German species may be identical with
Thinnfeldia rhomboidalis Ett. Kurr’s type-specimen, a portion of which is
reproduced in fig. 360, A, consists of a frond or large pinna characterised by
a prominent and broad rachis giving off alternate linear pinnae bearing
bluntly rounded, contiguous and basally concrescent pinnules having a
thick or revolute border and a central rib. The lateral veins are visible in the
ultimate segments of Kurr’s fossil. Saporta[1453] has described several
species, which he refers to Schimper’s genus, from French Jurassic strata: it
is, however, difficult to recognise some of the examples represented in his
illustrations as specifically distinct forms. This author notices the
resemblance of Lomatopteris to Thinnfeldia, not only in habit but in the
structure of the epidermal cells[1454]. In Lomatopteris and in Thinnfeldia the
cells have straight and not sinuous walls and the slightly sunken stomata are
Page 591
surrounded by a ring of epidermal cells. Salfeld[1455] has recently described
portions of fronds from Jurassic rocks of South-West Germany, which he
identifies as Lomatopteris jurensis. He disagrees with my view that
Lomatopteris does not differ sufficiently from Thinnfeldia to be accorded
generic autonomy, chiefly on the ground that the folded-over edge of the
pinnules is a distinguishing feature of Lomatopteris. There is, however, no
difference, in appearance at least, between the leaflets of some species of
Thinnfeldia, e.g. T. rhomboidalis from Liassic rocks of England[1456], and
those referred to Lomatopteris. In a later paper, Salfeld[1457] describes some
Portlandian fragments from North Germany as Lomatopteris Schimperi,
identifying them with a Wealden fossil of somewhat doubtful affinity,
which Schenk[1458] makes the type of his species. The Portlandian specimens
are described as tripinnate, with thick decurrent obtusely terminated
pinnules with a revolute edge. The general form of the frond is very similar
to that of L. jurensis. Salfeld publishes a photograph of a large specimen
which he describes as fertile and a drawing of a piece of a pinna: the latter
is reproduced in fig. 360, B. He speaks of sori occurring in two rows,
probably attached to lateral veins, in the groove between the midrib and the
revolute edge of the lamina. The sporangia are described as “nicht näher
bekannt[1459].” An examination of the figures reveals nothing as to the nature
of the “sori.” The specimens are considered by Salfeld to afford decisive
evidence against the view that Lomatopteris and Thinnfeldia are generically
identical. Nothing has so far been published which constitutes a valid
argument in favour of retaining Schimper’s generic name.
Cycadopteris.
Zigno[1460] founded the genus Cycadopteris on Italian Jurassic
impressions regarded by Schimper as indistinguishable from Lomatopteris.
As Solms-Laubach[1461] points out, the supposed sori of Cycadopteris
described by Zigno are not convincing. There appear to be no satisfactory
reasons for separating Cycadopteris from Lomatopteris, nor do the fronds
described under these names exhibit any important differences from
Thinnfeldia.
Ptilozamites.
portions of fronds from Jurassic rocks of South-West Germany, which he
identifies as Lomatopteris jurensis. He disagrees with my view that
Lomatopteris does not differ sufficiently from Thinnfeldia to be accorded
generic autonomy, chiefly on the ground that the folded-over edge of the
pinnules is a distinguishing feature of Lomatopteris. There is, however, no
difference, in appearance at least, between the leaflets of some species of
Thinnfeldia, e.g. T. rhomboidalis from Liassic rocks of England[1456], and
those referred to Lomatopteris. In a later paper, Salfeld[1457] describes some
Portlandian fragments from North Germany as Lomatopteris Schimperi,
identifying them with a Wealden fossil of somewhat doubtful affinity,
which Schenk[1458] makes the type of his species. The Portlandian specimens
are described as tripinnate, with thick decurrent obtusely terminated
pinnules with a revolute edge. The general form of the frond is very similar
to that of L. jurensis. Salfeld publishes a photograph of a large specimen
which he describes as fertile and a drawing of a piece of a pinna: the latter
is reproduced in fig. 360, B. He speaks of sori occurring in two rows,
probably attached to lateral veins, in the groove between the midrib and the
revolute edge of the lamina. The sporangia are described as “nicht näher
bekannt[1459].” An examination of the figures reveals nothing as to the nature
of the “sori.” The specimens are considered by Salfeld to afford decisive
evidence against the view that Lomatopteris and Thinnfeldia are generically
identical. Nothing has so far been published which constitutes a valid
argument in favour of retaining Schimper’s generic name.
Cycadopteris.
Zigno[1460] founded the genus Cycadopteris on Italian Jurassic
impressions regarded by Schimper as indistinguishable from Lomatopteris.
As Solms-Laubach[1461] points out, the supposed sori of Cycadopteris
described by Zigno are not convincing. There appear to be no satisfactory
reasons for separating Cycadopteris from Lomatopteris, nor do the fronds
described under these names exhibit any important differences from
Thinnfeldia.
Ptilozamites.
Page 592
Nathorst[1462] founded this genus on a remarkable series of specimens
from the Rhaetic Coal-beds of Scania and assigned it to the Cycadophyta.
The species Ptilozamites Heeri may be taken as a representative type. The
leaves are linear and simply pinnate. In the example shown on a much
reduced scale in fig. 361 the frond is 53 cm. long and 2·1 cm. broad. The
upper edge of each pinnule is straight or slightly concave; the lower edge is
rounded; the veins are slightly divergent and dichotomously branched (fig.
356, E, p. 539). In some of Nathorst’s specimens the broad rachis is forked
as in many Thinnfeldias.
As a comparison of fig. 356, A and E, shows, the pinnules of some
specimens of Thinnfeldia odontopteroides are identical with those of
Ptilozamites. In the latter genus the rachis is either unbranched or
occasionally forked, while in Thinnfeldia the branching may be of the
dichotomous or pinnate type. In Ptilozamites the segments appear to be
always without a midrib, while a median vein frequently occurs in those of
Thinnfeldia. There can be little doubt as to the very close alliance between
the Rhaetic species referred to these two genera. The name Ptilozamites
should perhaps be retained for such long and narrow fronds as that shown in
fig. 361: no species included in Thinnfeldia is known in which the rachis
reached so great a length without branching. The habit of Ptilozamites
Heeri predisposes one in favour of Nathorst’s opinion that the fronds are
Cycadean: we have no information in regard to the nature of the
reproductive organs.
from the Rhaetic Coal-beds of Scania and assigned it to the Cycadophyta.
The species Ptilozamites Heeri may be taken as a representative type. The
leaves are linear and simply pinnate. In the example shown on a much
reduced scale in fig. 361 the frond is 53 cm. long and 2·1 cm. broad. The
upper edge of each pinnule is straight or slightly concave; the lower edge is
rounded; the veins are slightly divergent and dichotomously branched (fig.
356, E, p. 539). In some of Nathorst’s specimens the broad rachis is forked
as in many Thinnfeldias.
As a comparison of fig. 356, A and E, shows, the pinnules of some
specimens of Thinnfeldia odontopteroides are identical with those of
Ptilozamites. In the latter genus the rachis is either unbranched or
occasionally forked, while in Thinnfeldia the branching may be of the
dichotomous or pinnate type. In Ptilozamites the segments appear to be
always without a midrib, while a median vein frequently occurs in those of
Thinnfeldia. There can be little doubt as to the very close alliance between
the Rhaetic species referred to these two genera. The name Ptilozamites
should perhaps be retained for such long and narrow fronds as that shown in
fig. 361: no species included in Thinnfeldia is known in which the rachis
reached so great a length without branching. The habit of Ptilozamites
Heeri predisposes one in favour of Nathorst’s opinion that the fronds are
Cycadean: we have no information in regard to the nature of the
reproductive organs.
Page 593
Fig. 361. Ptilozamites Heeri, Nath. (⅓ nat. size. After Nathorst.)
Ctenopteris.
This name was instituted by Saporta[1463], at Brongniart’s suggestion, for
Liassic species characterised by pinnules like those of Thinnfeldia, but
distinguished by the bipinnate habit of the frond. Saporta compares the
genus with the Palaeozoic leaves known as Odontopteris, and with Italian
Jurassic plants referred by Zigno to his genus Dichopteris.
The name Ctenozamites is applied by Nathorst[1464] to the type of frond
which Saporta, Zeiller, and other authors refer to Ctenopteris. Nathorst
Ctenopteris.
This name was instituted by Saporta[1463], at Brongniart’s suggestion, for
Liassic species characterised by pinnules like those of Thinnfeldia, but
distinguished by the bipinnate habit of the frond. Saporta compares the
genus with the Palaeozoic leaves known as Odontopteris, and with Italian
Jurassic plants referred by Zigno to his genus Dichopteris.
The name Ctenozamites is applied by Nathorst[1464] to the type of frond
which Saporta, Zeiller, and other authors refer to Ctenopteris. Nathorst
Page 594
instituted Ctenozamites for fossils agreeing in the form and venation of the
pinnules with his genus Ptilizamites but differing in being bipinnate and not
pinnate.
Fronds of Ctenopteris are characteristic of the Jurassic and Rhaetic
series; they are known only in the sterile condition. As Zeiller[1465] says,
Ctenopteris may be a member of the Cycadofilices, an extinct group
founded on Palaeozoic plants combining Cycadean and Filicinean
characters, and some of which are now known to be Pteridosperms. It is
probable that the genus is not a true fern: it is more likely to be a member of
the Cycadophyta or of some generalised extinct group.
Ctenopteris cycadea (Brongniart). Fig. 362.
1828. Filicites cycadea, Brongniart, Hist. Vég. foss. p. 387, Pl.
cxxix.
1832. Odontopteris cycadea, Berger, Verstein. Coburg Geg. p. 23,
Pl. iii.
1873. Ctenopteris cycadea, Saporta, Pal. Franç. Vol. i. p. 355, Pls.
xl. xli.
Frond bipinnate, broad rachis giving off branches at an acute angle; pinnules broadly linear,
slightly falcate, with several slightly divergent forked veins.
A frond very similar to the Lower Lias specimen from Dorsetshire
represented in fig. 362 was described by Leckenby as Ctenis Leckenbyi
(Bean MS.) from the Inferior Oolite of Yorkshire[1466]. Leckenby recognised
the possibility of a Cycadean affinity, but regarded the bipinnate habit as an
objection. The branched fronds of the Australian Cycad Bowenia supply an
answer to this objection. Several good examples of Ctenopteris cycadea are
figured by Schenk[1467] from Rhaetic rocks of Persia. Zeiller’s Tonkin
Rhaetic species, C. Sarrani[1468], affords a striking illustration of the
difficulty of drawing a clear line of separation between Ctenopteris and
some species of Thinnfeldia.
pinnules with his genus Ptilizamites but differing in being bipinnate and not
pinnate.
Fronds of Ctenopteris are characteristic of the Jurassic and Rhaetic
series; they are known only in the sterile condition. As Zeiller[1465] says,
Ctenopteris may be a member of the Cycadofilices, an extinct group
founded on Palaeozoic plants combining Cycadean and Filicinean
characters, and some of which are now known to be Pteridosperms. It is
probable that the genus is not a true fern: it is more likely to be a member of
the Cycadophyta or of some generalised extinct group.
Ctenopteris cycadea (Brongniart). Fig. 362.
1828. Filicites cycadea, Brongniart, Hist. Vég. foss. p. 387, Pl.
cxxix.
1832. Odontopteris cycadea, Berger, Verstein. Coburg Geg. p. 23,
Pl. iii.
1873. Ctenopteris cycadea, Saporta, Pal. Franç. Vol. i. p. 355, Pls.
xl. xli.
Frond bipinnate, broad rachis giving off branches at an acute angle; pinnules broadly linear,
slightly falcate, with several slightly divergent forked veins.
A frond very similar to the Lower Lias specimen from Dorsetshire
represented in fig. 362 was described by Leckenby as Ctenis Leckenbyi
(Bean MS.) from the Inferior Oolite of Yorkshire[1466]. Leckenby recognised
the possibility of a Cycadean affinity, but regarded the bipinnate habit as an
objection. The branched fronds of the Australian Cycad Bowenia supply an
answer to this objection. Several good examples of Ctenopteris cycadea are
figured by Schenk[1467] from Rhaetic rocks of Persia. Zeiller’s Tonkin
Rhaetic species, C. Sarrani[1468], affords a striking illustration of the
difficulty of drawing a clear line of separation between Ctenopteris and
some species of Thinnfeldia.
Page 595
Fig. 362. Ctenopteris cycadea, Brongn. (½ nat. size.) From a specimen in the British
Museum. [M.S.]
Ctenopteris is in all probability very closely related to Thinnfeldia and
Ptilozamites.
Dichopteris.
This genus was proposed by Zigno[1469] for some large specimens from
the Jurassic plant-beds of Northern Italy.
The bipinnate leaves are characterised by the great breadth of the rachis which is
dichotomously branched in the distal region (fig. 363); the linear pinnae reach a considerable
length. Pinnules relatively small, oblong and slightly contracted at the base; the decurrent and
confluent lamina forms a narrow wing to the main axis. Veins slightly divergent and forked, as in
Ptilozamites.
Dichopteris visianica, Zigno. Fig. 363.
Museum. [M.S.]
Ctenopteris is in all probability very closely related to Thinnfeldia and
Ptilozamites.
Dichopteris.
This genus was proposed by Zigno[1469] for some large specimens from
the Jurassic plant-beds of Northern Italy.
The bipinnate leaves are characterised by the great breadth of the rachis which is
dichotomously branched in the distal region (fig. 363); the linear pinnae reach a considerable
length. Pinnules relatively small, oblong and slightly contracted at the base; the decurrent and
confluent lamina forms a narrow wing to the main axis. Veins slightly divergent and forked, as in
Ptilozamites.
Dichopteris visianica, Zigno. Fig. 363.
Page 596
A specimen of this species in the Padua Museum has a total length of 83
cm. It has been elsewhere suggested[1470] that a fragment figured by Zigno as
a fertile example of this type is probably part of a frond of the
Osmundaceous fern Todites. Since this opinion was expressed I have had an
opportunity of examining the actual specimen at Padua: the circular patches
described by Zigno as sori appear to be irregularities in the matrix and not
an original feature.
Brongniart[1471] instituted the genus Pachypteris for some imperfectly
preserved English Jurassic fossils from Whitby, which he described as P.
lanceolata. Specimens have since been described[1472] from the Inferior
Oolite rocks of the Yorkshire coast. Brongniart described the pinnules as
being without veins or as possessing only a midrib. It is almost certain that
the apparent absence of veins in most specimens[1473] is due to the fleshy
nature of the segments and that the species P. lanceolata should be
transferred to Dichopteris.
Krasser[1474] has described a species from Cretaceous rocks of the island
of Lesina, off the Dalmatian coast, as Pachypteris dalmatica which is very
similar in habit to the English specimens and to Zigno’s Dichopteris
visianica. One of Krasser’s specimens is practically identical with
Dichopteris lanceolata (Brongn.), while in others the small pinnules are
replaced in some of the pinnae by a continuous lamina with a few distal
serrations. The latter form a link between the Dichopteris and Thinnfeldia
type of segment. Krasser gives a full résumé of opinions expressed by other
authors in regard to the position of Pachypteris (= Dichopteris) and decides
in favour of a Cycadean alliance.
cm. It has been elsewhere suggested[1470] that a fragment figured by Zigno as
a fertile example of this type is probably part of a frond of the
Osmundaceous fern Todites. Since this opinion was expressed I have had an
opportunity of examining the actual specimen at Padua: the circular patches
described by Zigno as sori appear to be irregularities in the matrix and not
an original feature.
Brongniart[1471] instituted the genus Pachypteris for some imperfectly
preserved English Jurassic fossils from Whitby, which he described as P.
lanceolata. Specimens have since been described[1472] from the Inferior
Oolite rocks of the Yorkshire coast. Brongniart described the pinnules as
being without veins or as possessing only a midrib. It is almost certain that
the apparent absence of veins in most specimens[1473] is due to the fleshy
nature of the segments and that the species P. lanceolata should be
transferred to Dichopteris.
Krasser[1474] has described a species from Cretaceous rocks of the island
of Lesina, off the Dalmatian coast, as Pachypteris dalmatica which is very
similar in habit to the English specimens and to Zigno’s Dichopteris
visianica. One of Krasser’s specimens is practically identical with
Dichopteris lanceolata (Brongn.), while in others the small pinnules are
replaced in some of the pinnae by a continuous lamina with a few distal
serrations. The latter form a link between the Dichopteris and Thinnfeldia
type of segment. Krasser gives a full résumé of opinions expressed by other
authors in regard to the position of Pachypteris (= Dichopteris) and decides
in favour of a Cycadean alliance.
Page 597
Fig. 363. Dichopteris visianica, Zigno. (⅓ nat. size. After Zigno.)
A French Jurassic plant which Saporta[1475] made the type of a new genus
Scleropteris, and described as S. Pomelii, appears to be indistinguishable
from Dichopteris.
Dichopteris, though conveniently retained as a distinct genus, agrees so
closely, in the broad and forked rachis and in the fleshy pinnules, with
Thinnfeldia that it would seem reasonable to regard the two genera as
members of the same group.
Several authors have drawn attention to the striking resemblance in form
and venation between the fronds of the Palaeozoic genus Odontopteris and
A French Jurassic plant which Saporta[1475] made the type of a new genus
Scleropteris, and described as S. Pomelii, appears to be indistinguishable
from Dichopteris.
Dichopteris, though conveniently retained as a distinct genus, agrees so
closely, in the broad and forked rachis and in the fleshy pinnules, with
Thinnfeldia that it would seem reasonable to regard the two genera as
members of the same group.
Several authors have drawn attention to the striking resemblance in form
and venation between the fronds of the Palaeozoic genus Odontopteris and
Page 598
those of Ctenopteris and Thinnfeldia. In Odontopteris, as in Neuropteris,
another Palaeozoic genus, the rachis occasionally bifurcates as in
Thinnfeldia and Dichopteris, and the ultimate segments of some species of
Odontopteris (fig. 366, A) are practically identical with those of Thinnfeldia
and Ptilozamites.
Odontopteris is probably a Pteridosperm. There is no adequate reason for
supposing that this group of plants which played a prominent part in the
Permo-Carboniferous floras was no longer in existence during the Mesozoic
era.
Odontopteris.
Brongniart[1476] instituted the genus Odontopteris for compound fronds
from the Coal-Measures characterised by pinnules attached by the whole
breadth of the base and traversed by numerous forked veins. Odontopteris
is very rare in British Carboniferous rocks and “appears to be restricted to
the Middle and Upper Coal-Measures[1477].”
another Palaeozoic genus, the rachis occasionally bifurcates as in
Thinnfeldia and Dichopteris, and the ultimate segments of some species of
Odontopteris (fig. 366, A) are practically identical with those of Thinnfeldia
and Ptilozamites.
Odontopteris is probably a Pteridosperm. There is no adequate reason for
supposing that this group of plants which played a prominent part in the
Permo-Carboniferous floras was no longer in existence during the Mesozoic
era.
Odontopteris.
Brongniart[1476] instituted the genus Odontopteris for compound fronds
from the Coal-Measures characterised by pinnules attached by the whole
breadth of the base and traversed by numerous forked veins. Odontopteris
is very rare in British Carboniferous rocks and “appears to be restricted to
the Middle and Upper Coal-Measures[1477].”
Page 599
Fig. 364.
A. Alethopteris lonchitica (Schloth.). ½ nat. size.
B. Mariopteris muricata (Schloth.). × 2.
C. Odontopteris cf. alpina (Presl). ⅗ nat. size.
D. O. cf. alpina. Portion of pinna enlarged.
(A–D. From photographs by Dr Kidston.)]
Fronds large, bipinnate or tripinnate, the main rachis, which may be dichotomously branched,
bears long linear pinnae with broadly linear or deltoid pinnules, acute or blunt, attached by the
whole of the base; the lower margin of the lamina, which is usually entire and rarely lobed (e.g.
Odontopteris osmundaeformis)[1478], is often decurrent on the axis of the pinna. The basal
pinnule of each pinna is frequently attached by a contracted base, and the lamina may differ in
form from that of the normal segments. Pinnules often occur on the main rachis, and in some
species the petiole bears modified pinnules which are larger than the ultimate segments of the
A. Alethopteris lonchitica (Schloth.). ½ nat. size.
B. Mariopteris muricata (Schloth.). × 2.
C. Odontopteris cf. alpina (Presl). ⅗ nat. size.
D. O. cf. alpina. Portion of pinna enlarged.
(A–D. From photographs by Dr Kidston.)]
Fronds large, bipinnate or tripinnate, the main rachis, which may be dichotomously branched,
bears long linear pinnae with broadly linear or deltoid pinnules, acute or blunt, attached by the
whole of the base; the lower margin of the lamina, which is usually entire and rarely lobed (e.g.
Odontopteris osmundaeformis)[1478], is often decurrent on the axis of the pinna. The basal
pinnule of each pinna is frequently attached by a contracted base, and the lamina may differ in
form from that of the normal segments. Pinnules often occur on the main rachis, and in some
species the petiole bears modified pinnules which are larger than the ultimate segments of the
Page 600
pinnae and in some cases Cyclopteroid in shape. The pinnules are traversed by numerous
dichotomously branched veins; if a midrib is present it dies out in the basal part of the lamina. In
some species (genus Mixoneura) pinnules of the Neuropteroid type, characterised by a well-
defined midrib, occur in association with typical Odontopteroid pinnules on the same pinna.
Fig. 365. Odontopteris minor, Brongn. (Rather less than ⅓ nat. size. After Zeiller.) [The
pinnules are omitted in the right-hand branch.]
The species represented in fig. 364, C, D, from the Middle Coal-
Measures of Barnsley, Yorkshire, illustrates the form and venation of the
Odontopteris type of pinnule. Another species, O. Reichiana Gutb.[1479], is
also recorded by Kidston from the Lower Coal-Measures of Lancashire.
Some unusually good specimens of the type-species of the genus
dichotomously branched veins; if a midrib is present it dies out in the basal part of the lamina. In
some species (genus Mixoneura) pinnules of the Neuropteroid type, characterised by a well-
defined midrib, occur in association with typical Odontopteroid pinnules on the same pinna.
Fig. 365. Odontopteris minor, Brongn. (Rather less than ⅓ nat. size. After Zeiller.) [The
pinnules are omitted in the right-hand branch.]
The species represented in fig. 364, C, D, from the Middle Coal-
Measures of Barnsley, Yorkshire, illustrates the form and venation of the
Odontopteris type of pinnule. Another species, O. Reichiana Gutb.[1479], is
also recorded by Kidston from the Lower Coal-Measures of Lancashire.
Some unusually good specimens of the type-species of the genus
Page 601
Odontopteris minor, Brongn., have been figured by Zeiller[1480] from the
Coal-Measures of Blanzy (fig. 365) which show the dichotomy of the main
axis and the occurrence of Aphlebiae on the petiole. The late Dr Weiss[1481]
divided Odontopteris into two sections, Xenopteris and Mixoneura, the
pinnules of the former having the form shown in fig. 364, D; while in
species of the latter sub-genus some of the pinnules are identical in form
and venation with those of Neuropteris except that they are attached by the
whole breadth of the base. Zeiller[1482] employs Mixoneura as a generic
designation. In an American species O. Wortheni Lesq.[1483] the pinnules
bear numerous hairs like those on some species of Neuropteris (fig. 373, p.
570). The large size of the fronds of Odontopteris suggested to Weiss[1484]
that they were borne on the stems of tree-ferns, but Grand’Eury’s[1485]
examination of specimens in the Coal-beds of central France led him to
picture the plant as bearing a tuft of leaves on a short subterranean stem.
Renault and Zeiller[1486], on the other hand, obtained evidence in the
Commentry Coal-field of fronds borne on elongated stems which grew on
the ground and were supported by stronger plants. Stur[1487] was the first to
suggest that Odontopteris should be excluded from the ferns.
Grand’Eury’s[1488] supposed fertile pinnules of Odontopteris do not afford
any satisfactory evidence of the sporangial nature of the small swellings
which he figures at the ends of the veins. This author pointed out several
years ago that the petioles of some species of Odontopteris possess the
anatomical features of Myeloxylon, a type of leaf-stalk which is now known
to belong to Pteridosperms. In a recent paper Grand’Eury[1489] records the
association of Odontopteris fronds with small seeds (Odontopterocarpus), a
discovery which leaves little or no doubt as to the Pteridospermic nature of
the genus. The fronds of Odontopteris are very similar in habit to those of
Neuropteris, another Pteridospermic genus.
The similarity between some Odontopteris and Thinnfeldia leaves, to
which attention has already been called, is well illustrated by O. genuina
Grand’Eury[1490], a pinnule of which is represented in fig. 366, A.
Odontopteris is a fairly widespread genus in Upper Carboniferous and
Lower Permian rocks, and is recorded also from Triassic strata: it is
represented in the Coal-fields of North America and in several parts of
Europe[1491].
Coal-Measures of Blanzy (fig. 365) which show the dichotomy of the main
axis and the occurrence of Aphlebiae on the petiole. The late Dr Weiss[1481]
divided Odontopteris into two sections, Xenopteris and Mixoneura, the
pinnules of the former having the form shown in fig. 364, D; while in
species of the latter sub-genus some of the pinnules are identical in form
and venation with those of Neuropteris except that they are attached by the
whole breadth of the base. Zeiller[1482] employs Mixoneura as a generic
designation. In an American species O. Wortheni Lesq.[1483] the pinnules
bear numerous hairs like those on some species of Neuropteris (fig. 373, p.
570). The large size of the fronds of Odontopteris suggested to Weiss[1484]
that they were borne on the stems of tree-ferns, but Grand’Eury’s[1485]
examination of specimens in the Coal-beds of central France led him to
picture the plant as bearing a tuft of leaves on a short subterranean stem.
Renault and Zeiller[1486], on the other hand, obtained evidence in the
Commentry Coal-field of fronds borne on elongated stems which grew on
the ground and were supported by stronger plants. Stur[1487] was the first to
suggest that Odontopteris should be excluded from the ferns.
Grand’Eury’s[1488] supposed fertile pinnules of Odontopteris do not afford
any satisfactory evidence of the sporangial nature of the small swellings
which he figures at the ends of the veins. This author pointed out several
years ago that the petioles of some species of Odontopteris possess the
anatomical features of Myeloxylon, a type of leaf-stalk which is now known
to belong to Pteridosperms. In a recent paper Grand’Eury[1489] records the
association of Odontopteris fronds with small seeds (Odontopterocarpus), a
discovery which leaves little or no doubt as to the Pteridospermic nature of
the genus. The fronds of Odontopteris are very similar in habit to those of
Neuropteris, another Pteridospermic genus.
The similarity between some Odontopteris and Thinnfeldia leaves, to
which attention has already been called, is well illustrated by O. genuina
Grand’Eury[1490], a pinnule of which is represented in fig. 366, A.
Odontopteris is a fairly widespread genus in Upper Carboniferous and
Lower Permian rocks, and is recorded also from Triassic strata: it is
represented in the Coal-fields of North America and in several parts of
Europe[1491].
Page 602
In some fronds included in Odontopteris the pinnae are characterised by
a broad irregularly lobed lamina which also forms a winged border to the
rachis. Examples of this form are afforded by Odontopteris Browni Sew.
[1492]
from the Burghersdorp Series (Triassic?) of Cape Colony, and O.
Fischeri described by Brongniart[1493] from the Permian of Russia. The
Russian species would perhaps be more appropriately placed in the genus
Callipteris, as Weiss[1494] suggests; the absence of venation in O. Browni
renders generic identification unsatisfactory.
a broad irregularly lobed lamina which also forms a winged border to the
rachis. Examples of this form are afforded by Odontopteris Browni Sew.
[1492]
from the Burghersdorp Series (Triassic?) of Cape Colony, and O.
Fischeri described by Brongniart[1493] from the Permian of Russia. The
Russian species would perhaps be more appropriately placed in the genus
Callipteris, as Weiss[1494] suggests; the absence of venation in O. Browni
renders generic identification unsatisfactory.
Page 603
Fig. 366.
A. Odontopteris genuina (Grand’Eury). (× 2⅝. After Renault and Zeiller.)
B. Callipteridium gigas (Gutb.). (× 2⅝. After Zeiller.)
C. Callipteris Pellati (Zeill.). (× 1¾. After Zeiller.)
D. C. lyratifolia (Goepp.). (× 1¾. After Zeiller.)
Callipteris.
Brongniart[1495] instituted this genus for certain species of supposed ferns
previously referred to the genera Pecopteris, Alethopteris, and Neuropteris.
Callipteris is a characteristic Permian plant which is almost certainly a
Pteridosperm. Zeiller has pointed out that such descriptions of fertile
specimens as have been written are unsatisfactory. A few years ago,
however, Grand’Eury[1496] recorded the occurrence of seeds in association
A. Odontopteris genuina (Grand’Eury). (× 2⅝. After Renault and Zeiller.)
B. Callipteridium gigas (Gutb.). (× 2⅝. After Zeiller.)
C. Callipteris Pellati (Zeill.). (× 1¾. After Zeiller.)
D. C. lyratifolia (Goepp.). (× 1¾. After Zeiller.)
Callipteris.
Brongniart[1495] instituted this genus for certain species of supposed ferns
previously referred to the genera Pecopteris, Alethopteris, and Neuropteris.
Callipteris is a characteristic Permian plant which is almost certainly a
Pteridosperm. Zeiller has pointed out that such descriptions of fertile
specimens as have been written are unsatisfactory. A few years ago,
however, Grand’Eury[1496] recorded the occurrence of seeds in association
Page 604
with Callipteris fronds in the Autun district, and in some cases they were
found attached to the pinnae and rachis. The seeds are ovoid or spherical
(5–10 mm. broad) and smaller than those of Neuropteris. The drawings of
fertile segments published by Weiss[1497] afford no indication of reproductive
organs. Potonié[1498] figures some pinnules of Callipteris conferta in which
the thick lamina is covered with sinuous grooves probably made by some
insect larvae: as he suggests, similar markings may have been mistaken for
the remains of sori. The occurrence of Callipteris fronds recorded by Weber
and Sterzel[1499] in association with Medullosa stems in the Lower Permian
of Saxony is in accordance with Grand’Eury’s conclusion.
Fronds reaching 1 metre in length, bipinnate or tripinnate, main rachis frequently exhibiting a
combination of dichotomous and pinnate branching. Pinnae linear, usually crowded, decurrent on
the rachis; the pinnules on the lower side of the pinnae are continued on to the rachis. Pinnules of
the Pecopteroid type, entire or slightly lobed, or of the Sphenopteroid type and more or less
deeply dissected (fig. 366 C, D), the lamina of adjacent pinnules concrescent; on the lower
pinnae the lamina may be continuous as in an Alethopteris pinnule. A midrib may extend almost
to the bluntly rounded apex of the ultimate segments, giving off oblique, simple, or forked veins,
the lowest of which arise directly from the rachis; in the Sphenopteroid forms the lateral veins
are given off at a more acute angle.
A striking feature of the genus is the occurrence of pinnules on the main
rachis, as in Odontopteris. Zeiller has wisely extended the application of
Callipteris to fronds possessing this character irrespective of the entire or
lobed form of the ultimate segments. He found among the numerous
examples of the genus obtained from Autun[1500] and Lodève[1501] transitional
forms connecting such species as C. conferta (fig. 367) and C. Pellati Zeill.
(fig. 366, C) in which the Pecopteroid pinnules are slightly lobed, with C.
lyratifolia (Goepp.) (fig. 366, D), C. flabellifera[1502] (Weiss), and C.
Bergeroni Zeill. characterised by deeply lobed Sphenopteroid segments.
Callipteris conferta (Sternberg)[1503]. Fig. 367.
1723. Scheuchzer, Herb. Diluv. Pl. ii., fig. 3.
1826. Neuropteris conferta, Sternberg, Flor. Vorwelt, p. 17.
1849. Callipteris conferta, Brongniart, Tableau, p. 24.
This polymorphic species (fig. 367) is one of the most characteristic
Permian plants. The oval-linear pinnules, attached by the whole base, occur
on both pinnae and rachis; this feature, the thick texture of the lamina, and
found attached to the pinnae and rachis. The seeds are ovoid or spherical
(5–10 mm. broad) and smaller than those of Neuropteris. The drawings of
fertile segments published by Weiss[1497] afford no indication of reproductive
organs. Potonié[1498] figures some pinnules of Callipteris conferta in which
the thick lamina is covered with sinuous grooves probably made by some
insect larvae: as he suggests, similar markings may have been mistaken for
the remains of sori. The occurrence of Callipteris fronds recorded by Weber
and Sterzel[1499] in association with Medullosa stems in the Lower Permian
of Saxony is in accordance with Grand’Eury’s conclusion.
Fronds reaching 1 metre in length, bipinnate or tripinnate, main rachis frequently exhibiting a
combination of dichotomous and pinnate branching. Pinnae linear, usually crowded, decurrent on
the rachis; the pinnules on the lower side of the pinnae are continued on to the rachis. Pinnules of
the Pecopteroid type, entire or slightly lobed, or of the Sphenopteroid type and more or less
deeply dissected (fig. 366 C, D), the lamina of adjacent pinnules concrescent; on the lower
pinnae the lamina may be continuous as in an Alethopteris pinnule. A midrib may extend almost
to the bluntly rounded apex of the ultimate segments, giving off oblique, simple, or forked veins,
the lowest of which arise directly from the rachis; in the Sphenopteroid forms the lateral veins
are given off at a more acute angle.
A striking feature of the genus is the occurrence of pinnules on the main
rachis, as in Odontopteris. Zeiller has wisely extended the application of
Callipteris to fronds possessing this character irrespective of the entire or
lobed form of the ultimate segments. He found among the numerous
examples of the genus obtained from Autun[1500] and Lodève[1501] transitional
forms connecting such species as C. conferta (fig. 367) and C. Pellati Zeill.
(fig. 366, C) in which the Pecopteroid pinnules are slightly lobed, with C.
lyratifolia (Goepp.) (fig. 366, D), C. flabellifera[1502] (Weiss), and C.
Bergeroni Zeill. characterised by deeply lobed Sphenopteroid segments.
Callipteris conferta (Sternberg)[1503]. Fig. 367.
1723. Scheuchzer, Herb. Diluv. Pl. ii., fig. 3.
1826. Neuropteris conferta, Sternberg, Flor. Vorwelt, p. 17.
1849. Callipteris conferta, Brongniart, Tableau, p. 24.
This polymorphic species (fig. 367) is one of the most characteristic
Permian plants. The oval-linear pinnules, attached by the whole base, occur
on both pinnae and rachis; this feature, the thick texture of the lamina, and
Page 605
the linear, obliquely set, pinnae render the fronds easily recognisable. The
fronds bore seeds.
Fig. 367. Callipteris conferta. From the Permian of Aschbach, Rhenish Prussia (British
Museum, No. 39052).
In a recent account of some Permian plants from Germany, Schuster[1504]
refers a portion of a frond to Callipteris conferta (Sternberg) var.
polymorpha Sterzel, which is characterised by unusually large and
polymorphic pinnules. In size and shape the pinnules recall those of
Neuropteridium validum Feist.
fronds bore seeds.
Fig. 367. Callipteris conferta. From the Permian of Aschbach, Rhenish Prussia (British
Museum, No. 39052).
In a recent account of some Permian plants from Germany, Schuster[1504]
refers a portion of a frond to Callipteris conferta (Sternberg) var.
polymorpha Sterzel, which is characterised by unusually large and
polymorphic pinnules. In size and shape the pinnules recall those of
Neuropteridium validum Feist.
Page 606
Callipteridium.
The name Callipteridium, created by Weiss[1505] as a sub-genus of
Odontopteris, is applied by Zeiller and other authors to a few Upper
Carboniferous and Permian species characterised by the occurrence of
simply pinnate pinnae on the main rachis between the bipinnate primary
pinnae. Single pinnules are borne directly on the rachis of the primary
pinnae between the pinnate branches. The form and venation of a typical
pinnule are shown in fig. 366, B. Callipteridium pteridium, originally
recorded by Schlotheim as Filicites pteridius[1506], has been fully described
by Renault and Zeiller from unusually large specimens found in the
Commentry Coal-field[1507]. This species illustrates the peculiar
morphological features of the genus. The main rachis of the tripinnate
fronds, several metres long, shows a combination of dichotomous and
pinnate branching; from the zigzag and forked axis are given off bipinnate
pinnae and, between these, shorter pinnate branches. The pinnules closely
resemble those of Callipteris conferta but reach a greater length; the
pinnules borne on the rachises of the lateral branches differ from the others
in their broader base and more triangular lamina.
No fertile specimens have been found. It is probable that Callipteridium
was not a true fern, and that White[1508] is correct in including it among the
Pteridosperms.
Archaeopteris.
In 1852 Forbes[1509] published a brief description of some supposed fern
fronds, found by the Geological Surveyors of Ireland in Upper Devonian
rocks of Kilkenny, under the name Cyclopteris hibernica. The Irish
specimens were more fully described by Baily[1510] in 1858. Fronds of the
same type were referred by other authors to Cyclopteris, Adiantites or
Noeggerathia, until Schimper[1511] proposed the generic name Palaeopteris
on the ground that the fronds described by Forbes and Baily are
distinguished by the nature of their fertile pinnae from the sterile leaves
included in Brongniart’s provisional genus Cyclopteris. The earlier use of
Palaeopteris by Geinitz for an entirely different plant led Dawson[1512] to
institute the genus Archaeopteris. The genus Archaeopteris may be defined
as follows:
The name Callipteridium, created by Weiss[1505] as a sub-genus of
Odontopteris, is applied by Zeiller and other authors to a few Upper
Carboniferous and Permian species characterised by the occurrence of
simply pinnate pinnae on the main rachis between the bipinnate primary
pinnae. Single pinnules are borne directly on the rachis of the primary
pinnae between the pinnate branches. The form and venation of a typical
pinnule are shown in fig. 366, B. Callipteridium pteridium, originally
recorded by Schlotheim as Filicites pteridius[1506], has been fully described
by Renault and Zeiller from unusually large specimens found in the
Commentry Coal-field[1507]. This species illustrates the peculiar
morphological features of the genus. The main rachis of the tripinnate
fronds, several metres long, shows a combination of dichotomous and
pinnate branching; from the zigzag and forked axis are given off bipinnate
pinnae and, between these, shorter pinnate branches. The pinnules closely
resemble those of Callipteris conferta but reach a greater length; the
pinnules borne on the rachises of the lateral branches differ from the others
in their broader base and more triangular lamina.
No fertile specimens have been found. It is probable that Callipteridium
was not a true fern, and that White[1508] is correct in including it among the
Pteridosperms.
Archaeopteris.
In 1852 Forbes[1509] published a brief description of some supposed fern
fronds, found by the Geological Surveyors of Ireland in Upper Devonian
rocks of Kilkenny, under the name Cyclopteris hibernica. The Irish
specimens were more fully described by Baily[1510] in 1858. Fronds of the
same type were referred by other authors to Cyclopteris, Adiantites or
Noeggerathia, until Schimper[1511] proposed the generic name Palaeopteris
on the ground that the fronds described by Forbes and Baily are
distinguished by the nature of their fertile pinnae from the sterile leaves
included in Brongniart’s provisional genus Cyclopteris. The earlier use of
Palaeopteris by Geinitz for an entirely different plant led Dawson[1512] to
institute the genus Archaeopteris. The genus Archaeopteris may be defined
as follows:
Page 607
Fronds bipinnate, reaching a considerable length (90 cm.); the stout rachis bears long linear
pinnae; sterile pinnules obovate or cuneate with an entire, lobed, fimbriate, or laciniate lamina
traversed by divergent dichotomously branched veins. The fertile pinnae usually occur on the
lower part of the rachis; pinnules with a much reduced lamina bear numerous fusiform or oval
exannulate sporangia (fig. 369, A, E, H), sessile or shortly stalked, singly, or in groups of two or
three. The base of the petiole is characterised by a pair of partially adnate stipules (fig. 369, C,
D), and single pinnules or scales occur in some species on the rachis between the pinnae and on
the petiole.
Fig. 368. Archaeopteris hibernica. (From a specimen in the Science and Art Museum,
Dublin. Rather less than ⅙ nat. size.)
Archaeopteris hibernica (Forbes). Figs. 368, 369, A–C.
pinnae; sterile pinnules obovate or cuneate with an entire, lobed, fimbriate, or laciniate lamina
traversed by divergent dichotomously branched veins. The fertile pinnae usually occur on the
lower part of the rachis; pinnules with a much reduced lamina bear numerous fusiform or oval
exannulate sporangia (fig. 369, A, E, H), sessile or shortly stalked, singly, or in groups of two or
three. The base of the petiole is characterised by a pair of partially adnate stipules (fig. 369, C,
D), and single pinnules or scales occur in some species on the rachis between the pinnae and on
the petiole.
Fig. 368. Archaeopteris hibernica. (From a specimen in the Science and Art Museum,
Dublin. Rather less than ⅙ nat. size.)
Archaeopteris hibernica (Forbes). Figs. 368, 369, A–C.
Page 608
The specimen from Kilkenny represented in fig. 368 has a length of over
80 cm. The upper pinnae bear numerous imbricate obovate pinnules (fig.
369, A, B) with an entire or very slightly fimbriate margin, while on the
shorter lower pinnae the ultimate segments are reduced to a slender axis
bearing numerous fusiform sporangia, 2–3 mm. in length. Kidston[1513] has
pointed out that sporangia occasionally occur on the edge of ordinary
pinnules, and he first recognised the stipular nature of the scale-like
appendages which Baily noticed on the swollen petiole base (5 cm. broad)
of the Irish species (fig. 369, C). Restorations of Archaeopteris hibernica
have been figured by Baily[1514] and by Carruthers[1515], but the description of
the fertile pinnae by the latter author requires modification in the light of
Kidston’s description of the Dublin specimens.
• • • • •
Archaeopteris is recorded from Upper Devonian rocks of the South of
Ireland, Belgium, Germany, Southern Russia, Bear Island, and Ellesmere
Land in the Arctic regions, Canada, Pennsylvania, and elsewhere. Many of
the specimens described under different names bear a close resemblance,
which in some cases probably amounts to specific identity, to A. hibernica.
A. Jacksoni originally described by Dawson[1516] and more recently by Smith
and White[1517] from Devonian rocks of Maine, the Canadian type A.
gaspiensis Daws., and some species figured by Lesquereux[1518] from
Pennsylvania, are examples of forms which present a striking similarity in
habit to the Irish species. The Belgian Devonian fossils named by
Crépin[1519] Palaeopteris hibernica var. minor are regarded by him as
probably identical with Goeppert’s species Cyclopteris Roemeriana from
the neighbourhood of Aachen. Heer recorded Archaeopteris Roemeriana
from Upper Devonian beds in Bear Island, and Nathorst[1520], who has
published a more complete account of the Arctic forms, draws attention to
the resemblance of some of them to A. hibernica. A species described by
Schmalhausen[1521] from the Upper Devonian of Southern Russia as A.
archetypus (fig. 369, D) appears to differ from A. hibernica in the slightly
less reduced lamina of the fertile segments. This species has been more
adequately illustrated by Nathorst[1522] from material collected in Ellesmere
Land: he is unable to confirm Schmalhausen’s statement that the pinnae are
spirally disposed.
80 cm. The upper pinnae bear numerous imbricate obovate pinnules (fig.
369, A, B) with an entire or very slightly fimbriate margin, while on the
shorter lower pinnae the ultimate segments are reduced to a slender axis
bearing numerous fusiform sporangia, 2–3 mm. in length. Kidston[1513] has
pointed out that sporangia occasionally occur on the edge of ordinary
pinnules, and he first recognised the stipular nature of the scale-like
appendages which Baily noticed on the swollen petiole base (5 cm. broad)
of the Irish species (fig. 369, C). Restorations of Archaeopteris hibernica
have been figured by Baily[1514] and by Carruthers[1515], but the description of
the fertile pinnae by the latter author requires modification in the light of
Kidston’s description of the Dublin specimens.
• • • • •
Archaeopteris is recorded from Upper Devonian rocks of the South of
Ireland, Belgium, Germany, Southern Russia, Bear Island, and Ellesmere
Land in the Arctic regions, Canada, Pennsylvania, and elsewhere. Many of
the specimens described under different names bear a close resemblance,
which in some cases probably amounts to specific identity, to A. hibernica.
A. Jacksoni originally described by Dawson[1516] and more recently by Smith
and White[1517] from Devonian rocks of Maine, the Canadian type A.
gaspiensis Daws., and some species figured by Lesquereux[1518] from
Pennsylvania, are examples of forms which present a striking similarity in
habit to the Irish species. The Belgian Devonian fossils named by
Crépin[1519] Palaeopteris hibernica var. minor are regarded by him as
probably identical with Goeppert’s species Cyclopteris Roemeriana from
the neighbourhood of Aachen. Heer recorded Archaeopteris Roemeriana
from Upper Devonian beds in Bear Island, and Nathorst[1520], who has
published a more complete account of the Arctic forms, draws attention to
the resemblance of some of them to A. hibernica. A species described by
Schmalhausen[1521] from the Upper Devonian of Southern Russia as A.
archetypus (fig. 369, D) appears to differ from A. hibernica in the slightly
less reduced lamina of the fertile segments. This species has been more
adequately illustrated by Nathorst[1522] from material collected in Ellesmere
Land: he is unable to confirm Schmalhausen’s statement that the pinnae are
spirally disposed.
Page 609
The species A. fimbriata (fig. 369, G) described by Nathorst from Bear
Island is characterised by the more deeply dissected lamina of the sterile
pinnules. In A. fissilis Schmal. from Russia and Ellesmere Land the lamina
(fig. 369, E, F) is cut up into filiform segments: a fertile pinnule of this
species is represented in fig. 369, E.
Some sterile impressions figured by Krasser[1523] from Palaeozoic strata
(Lower Carboniferous or Upper Devonian?) in the province of Nanshan in
China as Noeggerathia acuminifissa are considered by Zeiller[1524] to be
portions of an Archaeopteris or Rhacopteris frond. The resemblance to the
former genus is however by no means close enough to warrant a reference
to Archaeopteris. The sterile specimens described by Stur[1525] from the
Culm of Altendorf as species of Archaeopteris are probably not generically
identical with the Irish and Arctic species. The dichotomous branching of
the rachis in A. Tschermaki and A. Dawsoni is a feature unknown in
Archaeopteris. In the absence of fertile pinnae the separation of
Archaeopteris from Rhacopteris is by no means easy.
Island is characterised by the more deeply dissected lamina of the sterile
pinnules. In A. fissilis Schmal. from Russia and Ellesmere Land the lamina
(fig. 369, E, F) is cut up into filiform segments: a fertile pinnule of this
species is represented in fig. 369, E.
Some sterile impressions figured by Krasser[1523] from Palaeozoic strata
(Lower Carboniferous or Upper Devonian?) in the province of Nanshan in
China as Noeggerathia acuminifissa are considered by Zeiller[1524] to be
portions of an Archaeopteris or Rhacopteris frond. The resemblance to the
former genus is however by no means close enough to warrant a reference
to Archaeopteris. The sterile specimens described by Stur[1525] from the
Culm of Altendorf as species of Archaeopteris are probably not generically
identical with the Irish and Arctic species. The dichotomous branching of
the rachis in A. Tschermaki and A. Dawsoni is a feature unknown in
Archaeopteris. In the absence of fertile pinnae the separation of
Archaeopteris from Rhacopteris is by no means easy.
Page 610
Fig. 369.
A. Archaeopteris hibernica. Fertile pinna. Dublin Geological Survey Museum. (Reduced.
After Kidston.)
B. A. hibernica. Pinnule. (Slightly enlarged. After Carruthers.)
C. A. hibernica. Base of petiole. (Dublin Museum. After Kidston.)
D. A. archetypus. Base of petiole: Ellesmere Land. (After Nathorst. ⅚ nat. size.)
E. A. fissilis. Sporangia. (Slightly enlarged. After Schmalhausen.)
F. A. fissilis. Sterile pinnule. Ellesmere Land. (Slightly enlarged. After Nathorst.)
G. A. fimbriata. Bear Island. (After Nathorst. ⅚ nat. size.)
H. Archaeopteris sp. Ellesmere Land. (After Nathorst. ⅚ nat. size.)
Archaeopteris was regarded by Carruthers as a fern closely allied to
recent species of Hymenophyllaceae, but this conclusion was based upon an
interpretation of the fertile segments which Kidston[1526] has shown to be
A. Archaeopteris hibernica. Fertile pinna. Dublin Geological Survey Museum. (Reduced.
After Kidston.)
B. A. hibernica. Pinnule. (Slightly enlarged. After Carruthers.)
C. A. hibernica. Base of petiole. (Dublin Museum. After Kidston.)
D. A. archetypus. Base of petiole: Ellesmere Land. (After Nathorst. ⅚ nat. size.)
E. A. fissilis. Sporangia. (Slightly enlarged. After Schmalhausen.)
F. A. fissilis. Sterile pinnule. Ellesmere Land. (Slightly enlarged. After Nathorst.)
G. A. fimbriata. Bear Island. (After Nathorst. ⅚ nat. size.)
H. Archaeopteris sp. Ellesmere Land. (After Nathorst. ⅚ nat. size.)
Archaeopteris was regarded by Carruthers as a fern closely allied to
recent species of Hymenophyllaceae, but this conclusion was based upon an
interpretation of the fertile segments which Kidston[1526] has shown to be
Page 611
incorrect. The latter author regarded the presence of stipules and the
structure of the exannulate sporangia as evidence of a Marattiaceous
alliance. In a later reference to Archaeopteris, Kidston expresses the
opinion that the genus is not a true fern but a member of the Cycadofilices
or Pteridosperms, a view shared by Grand’Eury[1527] and doubtless by many
other palaeobotanists. The sporangia of Archaeopteris appear to be of the
same type as those of Dactylotheca (fig. 290, E, p. 399). Schmalhausen
gave expression to his disagreement with Nathorst and other authors who
referred Archaeopteris to the Marattiaceae by proposing the distinctive
group-name Archaeopterideae.
There can be little doubt that the reproductive organs of Archaeopteris so
far discovered are microsporangia, and that the plant bore seeds. The
sporangia are larger than those of any known fern and, as Kidston points
out, they are similar to those of Crossotheca which he has shown to be
microsporangia of the Pteridosperm Lyginodendron. The presence of
stipules in Archaeopteris hibernica, A. fimbriata, A. archetypus (fig. 369,
D) and probably throughout the genus does not materially affect the
question of taxonomic position. Stipules are a characteristic feature of
Marattiaceae and, in a reduced form, of Osmundaceae, but similar
appendages are borne at the base of the petiole of the Cycad Ceratozamia.
The occurrence of Aphlebiae on the rachis of Archaeopteris is a feature
shared by the fronds of Neuropteris and other Pteridosperms.
Neuropteris.
The fronds for which Brongniart[1528] created this genus, though suspected
by Stur in 1883 as wrongly classed among the ferns, have only recently
been shown to be the leaves of Pteridosperms. As yet only one case is
recorded in which
Neuropteris pinnae occur in organic connexion with seeds[1529], but it is
almost certain that the genus as a whole must be placed in this generalised
group. Renault[1530] pointed out that the petioles of Neuropteris fronds from
Autun had the anatomical features of Myeloxylon (petiole of Medullosa).
Since Kidston’s important discovery of seed-bearing pinnae of N.
heterophylla, Grand’Eury[1531] has recorded the association of Neuropteris
fronds with seeds in French Coal-fields. By some of the older authors
structure of the exannulate sporangia as evidence of a Marattiaceous
alliance. In a later reference to Archaeopteris, Kidston expresses the
opinion that the genus is not a true fern but a member of the Cycadofilices
or Pteridosperms, a view shared by Grand’Eury[1527] and doubtless by many
other palaeobotanists. The sporangia of Archaeopteris appear to be of the
same type as those of Dactylotheca (fig. 290, E, p. 399). Schmalhausen
gave expression to his disagreement with Nathorst and other authors who
referred Archaeopteris to the Marattiaceae by proposing the distinctive
group-name Archaeopterideae.
There can be little doubt that the reproductive organs of Archaeopteris so
far discovered are microsporangia, and that the plant bore seeds. The
sporangia are larger than those of any known fern and, as Kidston points
out, they are similar to those of Crossotheca which he has shown to be
microsporangia of the Pteridosperm Lyginodendron. The presence of
stipules in Archaeopteris hibernica, A. fimbriata, A. archetypus (fig. 369,
D) and probably throughout the genus does not materially affect the
question of taxonomic position. Stipules are a characteristic feature of
Marattiaceae and, in a reduced form, of Osmundaceae, but similar
appendages are borne at the base of the petiole of the Cycad Ceratozamia.
The occurrence of Aphlebiae on the rachis of Archaeopteris is a feature
shared by the fronds of Neuropteris and other Pteridosperms.
Neuropteris.
The fronds for which Brongniart[1528] created this genus, though suspected
by Stur in 1883 as wrongly classed among the ferns, have only recently
been shown to be the leaves of Pteridosperms. As yet only one case is
recorded in which
Neuropteris pinnae occur in organic connexion with seeds[1529], but it is
almost certain that the genus as a whole must be placed in this generalised
group. Renault[1530] pointed out that the petioles of Neuropteris fronds from
Autun had the anatomical features of Myeloxylon (petiole of Medullosa).
Since Kidston’s important discovery of seed-bearing pinnae of N.
heterophylla, Grand’Eury[1531] has recorded the association of Neuropteris
fronds with seeds in French Coal-fields. By some of the older authors
Page 612
Neuropteris was compared with Osmunda because of a similarity in
venation. In the frequent dichotomy of the frond and in the occurrence of
pinnules on the rachis, Neuropteris closely resembles Odontopteris[1532]:
there can be little doubt as to the close relationship of the Pteridosperms
possessing these two types of foliage. Neuropteris may be defined as
follows:
Fronds reaching a considerable size, probably in soma cases a length of 10 metres[1533]; bi- or
tri-pinnate; the rachis may be dichotomously branched (figs. 354, D; 370); both rachis and
petiole bear single pinnules, those on the latter frequently differ from the normal leaflets in their
larger Cyclopteroid laminae (fig. 370). Pinnules entire, rarely slightly lobed, broadly linear,
attached by a small portion of the base, which is usually more or less cordate. In N. Grangeri
Brongn. the pinnules are attached by a short pedicel[1534]. The midrib always dies out before
reaching the blunt or pointed apex of the lamina and gives off at an acute angle numerous
secondary veins characterised by their arched course and repeated forking.
venation. In the frequent dichotomy of the frond and in the occurrence of
pinnules on the rachis, Neuropteris closely resembles Odontopteris[1532]:
there can be little doubt as to the close relationship of the Pteridosperms
possessing these two types of foliage. Neuropteris may be defined as
follows:
Fronds reaching a considerable size, probably in soma cases a length of 10 metres[1533]; bi- or
tri-pinnate; the rachis may be dichotomously branched (figs. 354, D; 370); both rachis and
petiole bear single pinnules, those on the latter frequently differ from the normal leaflets in their
larger Cyclopteroid laminae (fig. 370). Pinnules entire, rarely slightly lobed, broadly linear,
attached by a small portion of the base, which is usually more or less cordate. In N. Grangeri
Brongn. the pinnules are attached by a short pedicel[1534]. The midrib always dies out before
reaching the blunt or pointed apex of the lamina and gives off at an acute angle numerous
secondary veins characterised by their arched course and repeated forking.
Page 613
Fig. 370. Neuropteris frond with Cyclopteris leaflets. English Coal-Measures. (From a block
given to me by Mr Carruthers. A.C.S.)
Potonié describes the secondary veins of the pinnules of Neuropteris
pseudogigantea[1535] as occasionally anastomosing, a feature which may be
regarded as a step towards the reticulate venation of the closely allied genus
Linopteris.
Renault[1536] described some petrified pinnules of Neuropteris in which
the mesophyll shows a differentiation into upper palisade tissue and lacunar
tissue below; the lower epidermis is infolded at intervals where grooves
given to me by Mr Carruthers. A.C.S.)
Potonié describes the secondary veins of the pinnules of Neuropteris
pseudogigantea[1535] as occasionally anastomosing, a feature which may be
regarded as a step towards the reticulate venation of the closely allied genus
Linopteris.
Renault[1536] described some petrified pinnules of Neuropteris in which
the mesophyll shows a differentiation into upper palisade tissue and lacunar
tissue below; the lower epidermis is infolded at intervals where grooves
Page 614
(probably stomatal) occur like those on the leaves of an Oleander (Nerium
oleander).
The rachises of Neuropteris fronds are described by Grand’Eury under
the generic name Aulacopteris[1537].
Neuropteris heterophylla, Brongniart[1538]. Figs. 354, E; 371.
This species is characteristic of the Lower Coal-Measures of Britain; it
occurs also in the Middle Coal-Measures and is a common type in Upper
Carboniferous rocks in various parts of the world. The fronds are large and
tripinnate, the rachis is often dichotomously branched and Cyclopteroid
pinnules may occur on the petiole. The pinnules, 5–20 mm. in length and 3–
8 mm. broad, have a rounded apex (fig. 354, E, p. 535).
oleander).
The rachises of Neuropteris fronds are described by Grand’Eury under
the generic name Aulacopteris[1537].
Neuropteris heterophylla, Brongniart[1538]. Figs. 354, E; 371.
This species is characteristic of the Lower Coal-Measures of Britain; it
occurs also in the Middle Coal-Measures and is a common type in Upper
Carboniferous rocks in various parts of the world. The fronds are large and
tripinnate, the rachis is often dichotomously branched and Cyclopteroid
pinnules may occur on the petiole. The pinnules, 5–20 mm. in length and 3–
8 mm. broad, have a rounded apex (fig. 354, E, p. 535).
Page 615
Fig. 371. Neuropteris heterophylla. From a specimen in the Manchester Museum. ½ nat.
size. M.S.
As shown in fig. 371 which represents a primary pinna, the small
pinnules on the lower branches are gradually replaced in the upper portion
of the specimen by falcate segments.
Neuropteris macrophylla, Brongniart[1539]. Figs. 354, D, D′; 372.
The rachis of the large fronds of this species illustrates the dichotomous
habit of many Neuropteris fronds, also the occurrence on the petiole of
large Cyclopteroid pinnules (cf. fig. 370). The small piece of a pinna
size. M.S.
As shown in fig. 371 which represents a primary pinna, the small
pinnules on the lower branches are gradually replaced in the upper portion
of the specimen by falcate segments.
Neuropteris macrophylla, Brongniart[1539]. Figs. 354, D, D′; 372.
The rachis of the large fronds of this species illustrates the dichotomous
habit of many Neuropteris fronds, also the occurrence on the petiole of
large Cyclopteroid pinnules (cf. fig. 370). The small piece of a pinna
Page 616
reproduced in fig. 372 shows the slender attachment of the segments, the
blunt apex, and the Neuropteroid venation. Single pinnules of this species
may be distinguished from those of N. Scheuchzeri by the blunter apex, the
absence of the pair of small Cyclopteroid pinnules on the same branch and
by the absence of hairs. N. macrophylla is characteristic of the Upper Coal-
Measures of Britain.
Fig. 372. Neuropteris macrophylla, Brongn. From a photograph by Mr Hemingway.
Neuropteris Scheuchzeri, Hoffmann. Figs. 354, F; 373.
Fragments of this well-known Coal-Measure species were figured by
Scheuchzer in his Herbarium Diluvianum[1540] as Lithosmunda minor, and
by Lhywd (Luidius[1541]) as Phyllites mineralis as early as 1760. Neuropteris
Scheuchzeri, so named by Hoffmann in 1826, is a type which many authors
have described under different names. Lesquereux[1542] figured it as N.
hirsuta from the Coal-fields of Pennsylvania, and under the same name it is
recorded by Fontaine and White[1543] from Permian rocks of Virginia. The
oval patches on the surface of a pinnule described by these authors as sori
are certainly not of that nature. The same species is described by
Bunbury[1544] from Nova Scotia as N. cordata Brongn. var. angustifolia. For
blunt apex, and the Neuropteroid venation. Single pinnules of this species
may be distinguished from those of N. Scheuchzeri by the blunter apex, the
absence of the pair of small Cyclopteroid pinnules on the same branch and
by the absence of hairs. N. macrophylla is characteristic of the Upper Coal-
Measures of Britain.
Fig. 372. Neuropteris macrophylla, Brongn. From a photograph by Mr Hemingway.
Neuropteris Scheuchzeri, Hoffmann. Figs. 354, F; 373.
Fragments of this well-known Coal-Measure species were figured by
Scheuchzer in his Herbarium Diluvianum[1540] as Lithosmunda minor, and
by Lhywd (Luidius[1541]) as Phyllites mineralis as early as 1760. Neuropteris
Scheuchzeri, so named by Hoffmann in 1826, is a type which many authors
have described under different names. Lesquereux[1542] figured it as N.
hirsuta from the Coal-fields of Pennsylvania, and under the same name it is
recorded by Fontaine and White[1543] from Permian rocks of Virginia. The
oval patches on the surface of a pinnule described by these authors as sori
are certainly not of that nature. The same species is described by
Bunbury[1544] from Nova Scotia as N. cordata Brongn. var. angustifolia. For
Page 617
a full synonymy of the species reference should be made to lists published
by Kidston[1545], White[1546], and Zeiller[1547].
Fig. 373. Neuropteris Scheuchzeri. From a specimen (v. 2009) in the British Museum. ¾ nat.
size.
The large tripinnate fronds are characterised by the long linear- or oval-
lanceolate pinnules (fig. 373)[1548] with a pointed apex and numerous bristle-
like hairs on the lamina; two much smaller Cyclopteroid segments occur at
the base of the pinnae which are terminated by the linear leaflets (fig. 354,
F, p. 535).
Neuropteris Scheuchzeri is characteristic of the Upper and Middle Coal-
Measures of Britain and is recorded from several localities in North
America and the Continent. Zalessky[1549] has recently recorded the species
from the Coal-Measures of Donetz. The frequent occurrence of detached
pinnules points to a caducous habit. Even single leaflets can, however, be
identified by their large size, the pointed apex, and hairy lamina. The hairs
are preserved as fine oblique lines simulating veins; they were so described
by Roemer[1550] who took them for cross-connexions between the secondary
veins and referred the pinnules to Gutbier’s genus Dictyopteris.
Another example of Neuropteris with hairy pinnules is described from
the Commentry Coal-field by Renault and Zeiller as N. horrida[1551]. The
oval-linear, bluntly rounded, pinnules are characterised by a median band of
hairs on each surface and a narrower strip at the edge of the lamina.
Cyclopteris.
This generic name was created by Brongniart in 1828[1552] for specimens
which he believed to be complete single leaves of orbicular or reniform
shape similar to those of Trichomanes reniforme. The lamina is traversed by
by Kidston[1545], White[1546], and Zeiller[1547].
Fig. 373. Neuropteris Scheuchzeri. From a specimen (v. 2009) in the British Museum. ¾ nat.
size.
The large tripinnate fronds are characterised by the long linear- or oval-
lanceolate pinnules (fig. 373)[1548] with a pointed apex and numerous bristle-
like hairs on the lamina; two much smaller Cyclopteroid segments occur at
the base of the pinnae which are terminated by the linear leaflets (fig. 354,
F, p. 535).
Neuropteris Scheuchzeri is characteristic of the Upper and Middle Coal-
Measures of Britain and is recorded from several localities in North
America and the Continent. Zalessky[1549] has recently recorded the species
from the Coal-Measures of Donetz. The frequent occurrence of detached
pinnules points to a caducous habit. Even single leaflets can, however, be
identified by their large size, the pointed apex, and hairy lamina. The hairs
are preserved as fine oblique lines simulating veins; they were so described
by Roemer[1550] who took them for cross-connexions between the secondary
veins and referred the pinnules to Gutbier’s genus Dictyopteris.
Another example of Neuropteris with hairy pinnules is described from
the Commentry Coal-field by Renault and Zeiller as N. horrida[1551]. The
oval-linear, bluntly rounded, pinnules are characterised by a median band of
hairs on each surface and a narrower strip at the edge of the lamina.
Cyclopteris.
This generic name was created by Brongniart in 1828[1552] for specimens
which he believed to be complete single leaves of orbicular or reniform
shape similar to those of Trichomanes reniforme. The lamina is traversed by
Page 618
numerous dichotomously branched veins which spread from the centre of
the base.
It was suspected by Lindley and Hutton[1553] that certain Cyclopteris
leaves belonged to the frond of a species of Neuropteris, and some years
later Lesquereux[1554] concluded that Brongniart’s genus was founded on
orbicular leaflets of Neuropteris. In 1869 Roehl[1555] figured a specimen of
Neuropteris bearing Cyclopteroid pinnules on its rachis. It is now
universally admitted that Cyclopteris is not a distinct genus and that the
specimens so named were borne as modified pinnules on the main rachis of
Neuropteris and Odontopteris. It is, however, convenient to retain the name
for detached leaflets which cannot be referred to the fronds on which they
were borne. A specimen found by Mr Hemingway in the Upper Coal-
Measures of Yorkshire and described in 1888[1556] affords a striking example
of the large size attained by what was probably a frond of Neuropteris. The
piece of main rachis reached a length of over 120 cm. and bore five pairs of
Cyclopteris pinnules, some of which were 7 cm. long and 5 cm. broad. The
complete frond must have reached a length of at least 4 metres. Fig. 370
shows some typical Cyclopteroid leaflets on the petiole of a Neuropteris
frond.
Linopteris.
The Upper Palaeozoic fronds included in this genus are more familiar as
species of Dictyopteris. Potonié[1557] has, however, pointed out that the
creation of this name by Lamouroux in 1809 for a genus of Brown Algae
which is still retained, makes it advisable to fall back upon the designation
Linopteris. Gutbier[1558] proposed the genus Dictyopteris in 1835: Linopteris
was first used by Presl[1559] in 1838. The fronds so named are identical with
species of Neuropteris except in the anastomosis of the secondary veins;
Linopteris bears to Neuropteris the same relation as Lonchopteris bears to
Alethopteris. As in Neuropteris, Cyclopteroid pinnules occur on the petioles
of Linopteris, but the veins form a fine reticulum. Grand’Eury[1560] records
the association of Linopteris Brongniarti with seeds belonging to the genus
Hexagonocarpon, a fact which points to the Pteridosperm nature of the
foliage.
the base.
It was suspected by Lindley and Hutton[1553] that certain Cyclopteris
leaves belonged to the frond of a species of Neuropteris, and some years
later Lesquereux[1554] concluded that Brongniart’s genus was founded on
orbicular leaflets of Neuropteris. In 1869 Roehl[1555] figured a specimen of
Neuropteris bearing Cyclopteroid pinnules on its rachis. It is now
universally admitted that Cyclopteris is not a distinct genus and that the
specimens so named were borne as modified pinnules on the main rachis of
Neuropteris and Odontopteris. It is, however, convenient to retain the name
for detached leaflets which cannot be referred to the fronds on which they
were borne. A specimen found by Mr Hemingway in the Upper Coal-
Measures of Yorkshire and described in 1888[1556] affords a striking example
of the large size attained by what was probably a frond of Neuropteris. The
piece of main rachis reached a length of over 120 cm. and bore five pairs of
Cyclopteris pinnules, some of which were 7 cm. long and 5 cm. broad. The
complete frond must have reached a length of at least 4 metres. Fig. 370
shows some typical Cyclopteroid leaflets on the petiole of a Neuropteris
frond.
Linopteris.
The Upper Palaeozoic fronds included in this genus are more familiar as
species of Dictyopteris. Potonié[1557] has, however, pointed out that the
creation of this name by Lamouroux in 1809 for a genus of Brown Algae
which is still retained, makes it advisable to fall back upon the designation
Linopteris. Gutbier[1558] proposed the genus Dictyopteris in 1835: Linopteris
was first used by Presl[1559] in 1838. The fronds so named are identical with
species of Neuropteris except in the anastomosis of the secondary veins;
Linopteris bears to Neuropteris the same relation as Lonchopteris bears to
Alethopteris. As in Neuropteris, Cyclopteroid pinnules occur on the petioles
of Linopteris, but the veins form a fine reticulum. Grand’Eury[1560] records
the association of Linopteris Brongniarti with seeds belonging to the genus
Hexagonocarpon, a fact which points to the Pteridosperm nature of the
foliage.
Page 619
Some fertile pinnules of Linopteris Schutzei (Roemer) are described by
Zeiller[1561] from Autun as bearing on the under surface of the lamina two
rows of long and pointed sporangia, probably united in groups. The
presumption is that these are microsporangia.
Fig. 374 is a reproduction of a careful drawing, originally published by
Zeiller[1562], of a pinnule of the type-specimen of Gutbier’s species
Linopteris neuropteroides. This species differs from Linopteris obliqua,
instituted by Bunbury[1563] for specimens obtained by Lyell[1564] from the
Coal-Measures of Nova Scotia, in the smaller size of the meshes. Linopteris
obliqua occurs in the Upper and Middle Coal-Measures of Britain; it is
recorded by Zeiller from Asia Minor, by Lesquereux[1565] from
Pennsylvania, and by other authors from several European localities. The
pinnules frequently occur detached from the frond and like those of some
species of Neuropteris were caducous. Linopteris is rare in British strata.
Fig. 374. Linopteris neuropteroides, Gutb. (Pinnule of type-specimen. Enlarged. After
Zeiller.)
Alethopteris.
The name Alethopteris, instituted by Sternberg[1566], is applied to
compound fronds often reaching a considerable size, exhibiting the
following features:
The linear pinnules are attached by the whole breadth of the base, with the lower edge of the
lamina decurrent and usually continuous with that of the next pinnule (figs. 290, A, p. 399; 375).
The ultimate segments are entire, with an acute or rounded apex and often characterised by a
fairly thick lamina convex on the upper surface. From a prominent midrib, continued to the apex
of the pinnule, numerous simple and forked secondary veins are given off at a wide angle, the
decurrent portion of the lamina being supplied by veins direct from the axis of the pinna. In the
upper part of a frond or primary pinna the pinnules may be replaced by a continuous, lobed, or
entire simple lamina. The main rachis occasionally exhibits dichotomous branching, but the
Zeiller[1561] from Autun as bearing on the under surface of the lamina two
rows of long and pointed sporangia, probably united in groups. The
presumption is that these are microsporangia.
Fig. 374 is a reproduction of a careful drawing, originally published by
Zeiller[1562], of a pinnule of the type-specimen of Gutbier’s species
Linopteris neuropteroides. This species differs from Linopteris obliqua,
instituted by Bunbury[1563] for specimens obtained by Lyell[1564] from the
Coal-Measures of Nova Scotia, in the smaller size of the meshes. Linopteris
obliqua occurs in the Upper and Middle Coal-Measures of Britain; it is
recorded by Zeiller from Asia Minor, by Lesquereux[1565] from
Pennsylvania, and by other authors from several European localities. The
pinnules frequently occur detached from the frond and like those of some
species of Neuropteris were caducous. Linopteris is rare in British strata.
Fig. 374. Linopteris neuropteroides, Gutb. (Pinnule of type-specimen. Enlarged. After
Zeiller.)
Alethopteris.
The name Alethopteris, instituted by Sternberg[1566], is applied to
compound fronds often reaching a considerable size, exhibiting the
following features:
The linear pinnules are attached by the whole breadth of the base, with the lower edge of the
lamina decurrent and usually continuous with that of the next pinnule (figs. 290, A, p. 399; 375).
The ultimate segments are entire, with an acute or rounded apex and often characterised by a
fairly thick lamina convex on the upper surface. From a prominent midrib, continued to the apex
of the pinnule, numerous simple and forked secondary veins are given off at a wide angle, the
decurrent portion of the lamina being supplied by veins direct from the axis of the pinna. In the
upper part of a frond or primary pinna the pinnules may be replaced by a continuous, lobed, or
entire simple lamina. The main rachis occasionally exhibits dichotomous branching, but the
Page 620
fronds are for the most part constructed on the pinnate plan. Single Cyclopteroid pinnules[1567]
occur on the petiole of some species of the genus.
In certain species of Alethopteris the pinnules appear to have been
deciduous as in Didymochlaena among recent ferns[1568]. A piece of cuticle
from the upper surface of a pinnule of Alethopteris Grandini (Brongn.)
figured by Zeiller[1569] shows very clearly the polygonal form and straight
walls of most of the epidermal cells, those above the veins being almost
rectangular. The position of the sunken stomata is revealed by small circular
spaces surrounded by a circle of cells.
The absence of fertile specimens of this common genus of Upper
Carboniferous plants led Stur[1570] to exclude it from the ferns. Although no
seeds have so far been found in organic connexion with an Alethopteris
frond, it is certain that some species, probably all, represent the foliage of
Pteridosperms. Renault was the first to describe petrified specimens of
Alethopteris fronds exhibiting the anatomical structure of Myeloxylon (leaf-
axis of Medullosa). The calcareous nodules from English Coal-seams
contain numerous fragments of the Myeloxylon type of rachis bearing
Alethopteroid pinnules.
The constant association of the fronds of Alethopteris lonchitica and
Trigonocarpon seeds noticed by Mr Hemingway in the Coal-Measures of
Yorkshire led him to regard the species as seed-bearing: it has since been
recognised as the foliage of the Pteridosperm Medullosa anglica[1571].
Grand’Eury[1572] has recorded the association in French Coal-fields of
species of Alethopteris with Trigonocarpon and Pachytesta seeds.
Alethopteris lonchitica (Schlotheim)[1573]. Figs. 364, A; 290, A.
This species, described by Schlotheim in 1820 as Filicites lonchiticus and
previously figured by Scheuchzer[1574], is abundant in the Middle and Lower
Coal-Measures of Britain[1575]. It is characterised by large tripinnate fronds,
probably quadripinnate in the lower part, bearing primary pinnae of a more
or less triangular form divided into pinnate branches replaced in the apical
region by linear segments. The pinnules, 8–30 mm. long and 3–5 broad, are
linear- or oval-lanceolate with an obtuse apex; the upper margin of the
lamina is slightly contracted at the base, while the lower edge is decurrent.
occur on the petiole of some species of the genus.
In certain species of Alethopteris the pinnules appear to have been
deciduous as in Didymochlaena among recent ferns[1568]. A piece of cuticle
from the upper surface of a pinnule of Alethopteris Grandini (Brongn.)
figured by Zeiller[1569] shows very clearly the polygonal form and straight
walls of most of the epidermal cells, those above the veins being almost
rectangular. The position of the sunken stomata is revealed by small circular
spaces surrounded by a circle of cells.
The absence of fertile specimens of this common genus of Upper
Carboniferous plants led Stur[1570] to exclude it from the ferns. Although no
seeds have so far been found in organic connexion with an Alethopteris
frond, it is certain that some species, probably all, represent the foliage of
Pteridosperms. Renault was the first to describe petrified specimens of
Alethopteris fronds exhibiting the anatomical structure of Myeloxylon (leaf-
axis of Medullosa). The calcareous nodules from English Coal-seams
contain numerous fragments of the Myeloxylon type of rachis bearing
Alethopteroid pinnules.
The constant association of the fronds of Alethopteris lonchitica and
Trigonocarpon seeds noticed by Mr Hemingway in the Coal-Measures of
Yorkshire led him to regard the species as seed-bearing: it has since been
recognised as the foliage of the Pteridosperm Medullosa anglica[1571].
Grand’Eury[1572] has recorded the association in French Coal-fields of
species of Alethopteris with Trigonocarpon and Pachytesta seeds.
Alethopteris lonchitica (Schlotheim)[1573]. Figs. 364, A; 290, A.
This species, described by Schlotheim in 1820 as Filicites lonchiticus and
previously figured by Scheuchzer[1574], is abundant in the Middle and Lower
Coal-Measures of Britain[1575]. It is characterised by large tripinnate fronds,
probably quadripinnate in the lower part, bearing primary pinnae of a more
or less triangular form divided into pinnate branches replaced in the apical
region by linear segments. The pinnules, 8–30 mm. long and 3–5 broad, are
linear- or oval-lanceolate with an obtuse apex; the upper margin of the
lamina is slightly contracted at the base, while the lower edge is decurrent.
Page 621
Fig. 375. Alethopteris Serlii (Brongn.). From a specimen in the York Museum. ¾ nat. size.
Alethopteris Serlii (Brongniart)[1576]. Fig. 375.
This species, figured by Parkinson in 1811, closely resembles A.
lonchitica, but is distinguished by the more crowded and relatively longer
pinnules which are joined to one another by a narrow connecting lamina
(Fig. 375). The secondary veins in A. Serlii are rather finer and more
numerous. Grand’Eury[1577] records the association of the seed Pachytesta
with fronds of this species in the Coal-Measures of St Étienne.
A. Serlii is very abundant in the Upper Coal-Measures but rare in the
Middle Coal-Measures of Britain[1578].
Lonchopteris.
Alethopteris Serlii (Brongniart)[1576]. Fig. 375.
This species, figured by Parkinson in 1811, closely resembles A.
lonchitica, but is distinguished by the more crowded and relatively longer
pinnules which are joined to one another by a narrow connecting lamina
(Fig. 375). The secondary veins in A. Serlii are rather finer and more
numerous. Grand’Eury[1577] records the association of the seed Pachytesta
with fronds of this species in the Coal-Measures of St Étienne.
A. Serlii is very abundant in the Upper Coal-Measures but rare in the
Middle Coal-Measures of Britain[1578].
Lonchopteris.
Page 622
This name was proposed by Brongniart[1579] for sterile fronds from Upper
Carboniferous rocks which are practically identical with species of
Alethopteris, but differ in the reticulate venation of the pinnules. It has been
pointed out in a previous chapter[1580] that Lonchopteris is usually used for
Palaeozoic species, the Wealden leaves, which were placed in this genus by
Brongniart, being transferred to Weichselia.
There can be little doubt as to the close relationship of Lonchopteris with
Alethopteris: both may be referred to the Pteridosperms. Lonchopteris
rugosa Brongn.[1581] (fig. 290, B, p. 399) and L. Bricei Brongn., both British
species, are fairly common in Upper Carboniferous strata. In L. rugosa, a
Middle Coal-Measures species, the anastomosing secondary veins form
polygonal meshes (fig. 290, B, p. 399) smaller than those of L. Bricei.
Pecopteris.
Reference has already been made to this genus in the chapter on
Marattiales, so far as regards certain species of fertile fronds the sporangia
of which resemble those of recent Marattiaceae. It is, however, by no means
safe to assume that such Pecopteris fronds were borne on stems having the
anatomical characters of ferns. The sporangia in some at least of the species
may have contained microspores. In one Upper Carboniferous species
usually referred to Pecopteris, P. Pluckeneti, Schlot., Grand’Eury[1582] has
recorded the occurrence of seeds on the pinnules of the ordinary fronds.
This species will be referred to in Volume iii. The substitution of such
generic names as Ptychocarpus, Asterotheca, Hawlea, Dactylotheca and
others for the purely provisional designation Pecopteris indicates a step
towards a conclusion as to natural affinity. The probability is that
Pecopteris, as applied to Palaeozoic species, in many cases stands for the
compound fronds of true ferns, but the possibility of the inclusion of those
of Pteridosperms in the same category is by no means excluded. The
designation Pecopteris may conveniently be retained for sterile bipinnate,
tripinnate, or quadripinnate fronds bearing pinnules having the following
characteristics:
Lamina short, attached to the rachis by the whole of the base and at a wide angle, with the
edges parallel or slightly converging towards the usually blunt apex; adjacent pinnules may be
continuous basally by a narrow lamina. A well-marked midrib extends to the apex and gives off
simple or forked lateral veins almost at right angles (fig. 352, D, p. 529).
Carboniferous rocks which are practically identical with species of
Alethopteris, but differ in the reticulate venation of the pinnules. It has been
pointed out in a previous chapter[1580] that Lonchopteris is usually used for
Palaeozoic species, the Wealden leaves, which were placed in this genus by
Brongniart, being transferred to Weichselia.
There can be little doubt as to the close relationship of Lonchopteris with
Alethopteris: both may be referred to the Pteridosperms. Lonchopteris
rugosa Brongn.[1581] (fig. 290, B, p. 399) and L. Bricei Brongn., both British
species, are fairly common in Upper Carboniferous strata. In L. rugosa, a
Middle Coal-Measures species, the anastomosing secondary veins form
polygonal meshes (fig. 290, B, p. 399) smaller than those of L. Bricei.
Pecopteris.
Reference has already been made to this genus in the chapter on
Marattiales, so far as regards certain species of fertile fronds the sporangia
of which resemble those of recent Marattiaceae. It is, however, by no means
safe to assume that such Pecopteris fronds were borne on stems having the
anatomical characters of ferns. The sporangia in some at least of the species
may have contained microspores. In one Upper Carboniferous species
usually referred to Pecopteris, P. Pluckeneti, Schlot., Grand’Eury[1582] has
recorded the occurrence of seeds on the pinnules of the ordinary fronds.
This species will be referred to in Volume iii. The substitution of such
generic names as Ptychocarpus, Asterotheca, Hawlea, Dactylotheca and
others for the purely provisional designation Pecopteris indicates a step
towards a conclusion as to natural affinity. The probability is that
Pecopteris, as applied to Palaeozoic species, in many cases stands for the
compound fronds of true ferns, but the possibility of the inclusion of those
of Pteridosperms in the same category is by no means excluded. The
designation Pecopteris may conveniently be retained for sterile bipinnate,
tripinnate, or quadripinnate fronds bearing pinnules having the following
characteristics:
Lamina short, attached to the rachis by the whole of the base and at a wide angle, with the
edges parallel or slightly converging towards the usually blunt apex; adjacent pinnules may be
continuous basally by a narrow lamina. A well-marked midrib extends to the apex and gives off
simple or forked lateral veins almost at right angles (fig. 352, D, p. 529).
Page 623
Hydathodes like those on the leaflets of Polypodium vulgare and other recent ferns[1583] are
occasionally seen at the ends of the lateral veins of Pecopteris pinnules.
In addition to the examples of Palaeozoic fronds with the Pecopteris
form of pinnule referred to in chapter xxii., the species Pecopteris
arborescens may be briefly described.
Pecopteris arborescens (Schlotheim)[1584]. Figs. 352, D: 376.
The species named by Schlotheim Filicites arborescens in 1804 is
characteristic of the Upper Coal-Measures and is recorded also from
Permian strata[1585].
Fronds large; the rachis, which may reach a breadth of 3 cm.[1586], gives off long ovoid-
lanceolate pinnae in two alternate rows (fig. 376); pinnules small, 1·5–4mm. long and 1–2mm.
broad, contiguous, with rounded apex, attached approximately at right angles; the upper surface
of the lamina is slightly convex and may be hairy[1587]. The fertile pinnules, identical in shape
with the sterile, bear groups of ovoid exannulate sporangia (synangia). The midrib extends to the
apex of the pinnule and gives off simple veins at a wide angle (fig. 352, D).
Our knowledge of the reproductive organs is very meagre. Grand’Eury
described the synangia as consisting of 3–5 sporangia borne on a central
receptacle; sporangia have been described also by Stur[1588], Renault and
Zeiller[1589], and Potonié[1590], but no fertile British specimens are recorded.
Stur places this species in the genus Scolecopteris, and Potonié regards the
sporangia found by him on Permian fronds, which may be identical with
Pecopteris arborescens, as conforming to those of the Asterotheca type. It
is impossible to decide on the evidence available whether this species is a
Pteridosperm or a fern, but there is a natural inclination in doubtful cases to
give preference to the first of these two choices.
occasionally seen at the ends of the lateral veins of Pecopteris pinnules.
In addition to the examples of Palaeozoic fronds with the Pecopteris
form of pinnule referred to in chapter xxii., the species Pecopteris
arborescens may be briefly described.
Pecopteris arborescens (Schlotheim)[1584]. Figs. 352, D: 376.
The species named by Schlotheim Filicites arborescens in 1804 is
characteristic of the Upper Coal-Measures and is recorded also from
Permian strata[1585].
Fronds large; the rachis, which may reach a breadth of 3 cm.[1586], gives off long ovoid-
lanceolate pinnae in two alternate rows (fig. 376); pinnules small, 1·5–4mm. long and 1–2mm.
broad, contiguous, with rounded apex, attached approximately at right angles; the upper surface
of the lamina is slightly convex and may be hairy[1587]. The fertile pinnules, identical in shape
with the sterile, bear groups of ovoid exannulate sporangia (synangia). The midrib extends to the
apex of the pinnule and gives off simple veins at a wide angle (fig. 352, D).
Our knowledge of the reproductive organs is very meagre. Grand’Eury
described the synangia as consisting of 3–5 sporangia borne on a central
receptacle; sporangia have been described also by Stur[1588], Renault and
Zeiller[1589], and Potonié[1590], but no fertile British specimens are recorded.
Stur places this species in the genus Scolecopteris, and Potonié regards the
sporangia found by him on Permian fronds, which may be identical with
Pecopteris arborescens, as conforming to those of the Asterotheca type. It
is impossible to decide on the evidence available whether this species is a
Pteridosperm or a fern, but there is a natural inclination in doubtful cases to
give preference to the first of these two choices.
Page 624
Fig. 376. Pecopteris arborescens (Schloth.). From the Upper Coal-Measures of Radstock.
From a photograph by Dr Kidston. Reduced.
The numerous fronds from Carboniferous and Permian rocks described
as species of Pecopteris exhibit a considerable range of variation in the
form of the pinnules. In many species the pinnules are of the type
represented in fig. 352, D; in others the lamina of the ultimate segments is
slightly contracted at the base and the secondary veins are given off at a
more acute angle, as in Pecopteris polymorpha, Brongn.[1591] In Pecopteris
unita, Brongn., already described as Ptychocarpus unita[1592], the pinnules
are joined together except in the apical region. Some fronds included in
Pecopteris possess pinnules in which Pecopteroid and Sphenopteroid
features are combined; P. Sterzeli, Zeill.[1593] and P. Pluckeneti, Schlot. are
examples of fronds in which the pinnules are lobed as in Sphenopteris, but
the base of the lamina is only slightly contracted and the venation is not that
of typical Sphenopteris species.
From a photograph by Dr Kidston. Reduced.
The numerous fronds from Carboniferous and Permian rocks described
as species of Pecopteris exhibit a considerable range of variation in the
form of the pinnules. In many species the pinnules are of the type
represented in fig. 352, D; in others the lamina of the ultimate segments is
slightly contracted at the base and the secondary veins are given off at a
more acute angle, as in Pecopteris polymorpha, Brongn.[1591] In Pecopteris
unita, Brongn., already described as Ptychocarpus unita[1592], the pinnules
are joined together except in the apical region. Some fronds included in
Pecopteris possess pinnules in which Pecopteroid and Sphenopteroid
features are combined; P. Sterzeli, Zeill.[1593] and P. Pluckeneti, Schlot. are
examples of fronds in which the pinnules are lobed as in Sphenopteris, but
the base of the lamina is only slightly contracted and the venation is not that
of typical Sphenopteris species.
Page 625
The species to which Potonié has applied the generic name
Alloiopteris[1594] also illustrates the impossibility of drawing a sharp line
between Pecopteris and Sphenopteris. The fronds already described in
chapter xxv. under the designation Corynepteris bear pinnules with a
contracted base; in some species the lamina is lobed, but in others (fig. 354,
G) it is entire with a midrib nearer one edge than the other. The species
which Potonié assigns to Alloiopteris, like many other Sphenopteroid and
Pecopteroid fronds, are characterised by the occurrence of an abnormal
pinnule (aphlebia) at the base of each pinna (fig. 354, G, p. 535). Young
fronds of Pecopteris are occasionally met with showing very clearly the
circinate vernation of the pinnae as in the leaves of Cycas and Angiopteris
represented in fig. 220, p. 283. The genus Spiropteris was created by
Schimper[1595] for coiled unexpanded fronds of fossil ferns; it is however
superfluous to apply a distinctive term to specimens of this kind.
The designation Pecopteris is employed chiefly for leaves of Palaeozoic
age which are unknown in the fertile state, or do not afford sufficient
evidence as to the nature of the sporangia to justify the substitution of a
special generic name. Many Mesozoic species have also been referred to
Pecopteris, but most of these are more appropriately included in
Brongniart’s later genus Cladophlebis. The pinnules of Cladophlebis, as
Brongniart pointed out, are intermediate between Pecopteris and
Neuropteris; they are usually attached by the whole breadth of the base, as
in Pecopteris, but the more acute origin, more arched form, and more
frequent dichotomy of the lateral veins are features shared by Neuropteris.
As a rule, Mesozoic sterile fronds with straight or folded, entire or dentate
pinnules are of the Cladophlebis type: this genus is especially characteristic
of Rhaetic and Jurassic floras. Examples of Cladophlebis pinnules are
shown in figs. 256, 257 (pp. 340, 342). It is to be regretted that authors do
not make more use of the generic name Cladophlebis in describing sterile
fronds, instead of following the misleading and unscientific practice of
employing such genera as Pteris, Asplenites, and others on wholly
insufficient grounds.
Alloiopteris[1594] also illustrates the impossibility of drawing a sharp line
between Pecopteris and Sphenopteris. The fronds already described in
chapter xxv. under the designation Corynepteris bear pinnules with a
contracted base; in some species the lamina is lobed, but in others (fig. 354,
G) it is entire with a midrib nearer one edge than the other. The species
which Potonié assigns to Alloiopteris, like many other Sphenopteroid and
Pecopteroid fronds, are characterised by the occurrence of an abnormal
pinnule (aphlebia) at the base of each pinna (fig. 354, G, p. 535). Young
fronds of Pecopteris are occasionally met with showing very clearly the
circinate vernation of the pinnae as in the leaves of Cycas and Angiopteris
represented in fig. 220, p. 283. The genus Spiropteris was created by
Schimper[1595] for coiled unexpanded fronds of fossil ferns; it is however
superfluous to apply a distinctive term to specimens of this kind.
The designation Pecopteris is employed chiefly for leaves of Palaeozoic
age which are unknown in the fertile state, or do not afford sufficient
evidence as to the nature of the sporangia to justify the substitution of a
special generic name. Many Mesozoic species have also been referred to
Pecopteris, but most of these are more appropriately included in
Brongniart’s later genus Cladophlebis. The pinnules of Cladophlebis, as
Brongniart pointed out, are intermediate between Pecopteris and
Neuropteris; they are usually attached by the whole breadth of the base, as
in Pecopteris, but the more acute origin, more arched form, and more
frequent dichotomy of the lateral veins are features shared by Neuropteris.
As a rule, Mesozoic sterile fronds with straight or folded, entire or dentate
pinnules are of the Cladophlebis type: this genus is especially characteristic
of Rhaetic and Jurassic floras. Examples of Cladophlebis pinnules are
shown in figs. 256, 257 (pp. 340, 342). It is to be regretted that authors do
not make more use of the generic name Cladophlebis in describing sterile
fronds, instead of following the misleading and unscientific practice of
employing such genera as Pteris, Asplenites, and others on wholly
insufficient grounds.
Page 626
Page 627
LIST OF WORKS REFERRED TO IN THE
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Arber, E. A. N. (02) On the distribution of the Glossopteris Flora. Geol.
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—— (05) Catalogue of the fossil plants of the Glossopteris Flora in the
British Museum. A monograph of the Permo-Carboniferous Flora of
India and the Southern Hemisphere. London.
—— (052) The Sporangium-like organs of Glossopteris Browniana,
Brongn. Quart. Journ. Geol. Soc. vol. lxi. p. 324
—— (053) The fossil flora of the Culm-measures of N. W. Devon &c. Phil.
Trans. R. Soc. vol. cxcvii. p. 291.
—— (06) On the past history of Ferns. Annals Bot. vol. xx. p. 215.
Arber, E. A. N. and H. H. Thomas. (08) On the structure of Sigillaria
scutellata, Brongn. and other Eusigillarian stems, in comparison with
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Armour, H. M. (07) On the Sorus of Dipteris. New Phytologist, vol. vi. p.
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Atkinson, G. F. (94) The study of the biology of Ferns, by the collodion
method. New York.
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du Nord de la Russie, d’une flore Glossoptérienne &c. Compt. Rend.
vol. cxxxii. p. 591.
Arber, E. A. N. (02) On the distribution of the Glossopteris Flora. Geol.
Mag. vol. ix. p. 346.
—— (022) The Clarke collection of fossil plants from New South Wales.
Quart. Journ. Geol. Soc. vol. lviii. p. 1.
—— (03) Notes on some fossil plants collected by Mr Molyneux in
Rhodesia. Quart. Journ. Geol. Soc. vol. lix. p. 288.
—— (05) Catalogue of the fossil plants of the Glossopteris Flora in the
British Museum. A monograph of the Permo-Carboniferous Flora of
India and the Southern Hemisphere. London.
—— (052) The Sporangium-like organs of Glossopteris Browniana,
Brongn. Quart. Journ. Geol. Soc. vol. lxi. p. 324
—— (053) The fossil flora of the Culm-measures of N. W. Devon &c. Phil.
Trans. R. Soc. vol. cxcvii. p. 291.
—— (06) On the past history of Ferns. Annals Bot. vol. xx. p. 215.
Arber, E. A. N. and H. H. Thomas. (08) On the structure of Sigillaria
scutellata, Brongn. and other Eusigillarian stems, in comparison with
those of other Palaeozoic Lycopods. Phil. Trans. R. Soc. vol. cc. p.
133.
Armour, H. M. (07) On the Sorus of Dipteris. New Phytologist, vol. vi. p.
238.
Atkinson, G. F. (94) The study of the biology of Ferns, by the collodion
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Auerbach, J. and H. Trautschold. (60) Ueber die Kohlen von Central
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from the Upper Devonian or Lower Carboniferous strata at Kiltorkan
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meeting, 1858.)
—— (60) On Corynepteris, a new generic form of fossil fern. Journ. Geol.
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—— (75) Figures of characteristic British fossils. London.
Baker, J. G. (67) Descriptions of six new species of simple fronded
Hymenophyllaceae. Journ. Linn. Soc. vol. ix. p. 335.
—— (68) On the geographical distribution of Ferns. Trans. Linn. Soc. vol.
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—— (68) See Hooker, Sir W. J. and J. G. Baker.
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Hill, County Kilkenny. Brit. Assoc. Rep. London, 1859, p. 75. (Leeds
meeting, 1858.)
—— (60) On Corynepteris, a new generic form of fossil fern. Journ. Geol.
Soc. Dublin, vol. viii. p. 237.
—— (75) Figures of characteristic British fossils. London.
Baker, J. G. (67) Descriptions of six new species of simple fronded
Hymenophyllaceae. Journ. Linn. Soc. vol. ix. p. 335.
—— (68) On the geographical distribution of Ferns. Trans. Linn. Soc. vol.
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—— (68) See Hooker, Sir W. J. and J. G. Baker.
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Balfour, J. H. (57) On the occurrence in coal of peculiar vegetable
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Barber, C. A. (89) On the structure and development of the bulb in
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Bather, F. A. (07) Nathorst’s use of Collodion imprints in the study of fossil
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Benson, Margaret. (04) Telangium Scotti, a new species of Telangium
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Bernard, C. (04) Le bois centripète dans les feuilles de Conifères. Bot.
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Bertrand, C. E. (81) Recherches sur les Tmésiptéridées. Arch. Bot. Nord
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—— (82) Phylloglossum. Arch. Bot. Nord France, vol. ii. p. 70.
—— (91) Remarques sur le Lepidodendron Harcourtii de Witham. Trav.
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Page 633
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vol. i. Abth. 3.
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Page 637
Feistmantel, O. (72) Ueber Baumfarrenreste der böhmischen Steinkohlen.
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India. Foss. Flor. Lower Gondwanas, i.
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iii.
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India. Foss. Flor. Lower Gondwanas, i.
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iv. pt. i.
Fischer, F. (04) Zur Nomenclatur von Lepidodendron und zur Artkritik
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1903 (April 6th).
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Mesozoic Flora of Virginia. Monographs U. S. Geol. Surv. Vol. vi.
—— (89) The Potomac or younger Mesozoic Flora of Virginia. U. S. Geol.
Surv. Monographs, vi.
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Fontaine, W. M. and I. C. White. (80) The Permian or Upper-
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Page 638
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—— (53) On the fossils of the Yellow Sandstone of the South of Ireland.
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Ford, S. O. (02) On the anatomy of Ceratopteris thalictroides L., Annals
Bot. vol. xvi. p. 95.
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—— (06) See Seward, A. C. and S. O. Ford.
Freeman, W. G. (99) See Farmer, J. B. and W. G. Freeman.
Frič, A. and E. Bayer. (01) Studien im Gebiete der Böhmischen
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Gardner, J. S. and C. von Ettingshausen. (82) A monograph of the British
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Geikie, Sir Archibald. (03) Text-book of Geology. 2 vols. London.
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Geinitz, H. B. (72) Fossile Myriopoden in dem Rothliegenden bei
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Page 639
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Gilkinet, A. (75) Sur quelques plantes de l’étage du poudingue de Burnot.
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—— (54) See Roemer, F. A.
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—— (05) Sur les graines trouvées attachées au Pecopteris Pluckeneti,
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—— (052) Sur les graines de Sphenopteris &c. Compt. Rend. cxli. p. 812.
Provinzen La Rioja &c. Palaeontograph. Suppl. iii.
Germar, E. F. (52) Sigillaria Sternbergi Münster, aus dem bunten
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Löbejün im Saalkreise. Halle.
Geyler, H. T. (77) Ueber fossile Pflanzen aus der Juraformation Japans.
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Giesenhagen, C. (90) Die Hymenophyllaceen. Flora, p. 411.
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Gilkinet, A. (75) Sur quelques plantes de l’étage du poudingue de Burnot.
Acad. Roy. Belg. [2] vol. xl. No. 8.
Goebel, K. (91) Pflanzenbiologische Schilderungen. Teil 2. Marburg.
—— (05) Organography of Plants. Vol. ii. (Trans. by J. B. Balfour.) Oxford.
Goeppert, H. R. (41) Die Gattungen der fossilen Pflanzen. Bonn.
—— (32) Fossile Flora des Uebergangsgebirges. Nov. Act. Caes. Leop.-
Carol. Vol. xiv. (Supplt.).
—— (54) See Roemer, F. A.
Goldenberg, F. (55–62) Flora Saraepontana Fossilis. Saarbrücken.
Gordon, W. T. (08) On the Prothallus of Lepidodendron Veltheimianum.
Trans. Bot. Soc. Edinburgh, vol. xxiii. p. 330.
—— (09) On the structure of a new Zygopteris. Nature. (Botany at the
British Association.) Vol. lxxxi. p. 537.
Grand’Eury, C. (75) See Renault, B. and C. Grand’Eury.
—— (04) Sur les graines des Neuroptéridées. Compt. Rend. cxxxix. p. 782.
—— (05) Sur les graines trouvées attachées au Pecopteris Pluckeneti,
Schlot. Compt. Rend. vol. cxl. p. 920.
—— (052) Sur les graines de Sphenopteris &c. Compt. Rend. cxli. p. 812.
Page 640
—— (06) Sur les graines et inflorescences des Callipteris. Compt. Rend.
cxliii. p. 664.
—— (08) Sur les organes et la mode de végétation des Neuroptéridées et
autres Ptéridospermes. Compt. Rend. clxvi. p. 1241.
Gresley, W. S. (89) Note on further discoveries of Stigmaria (? ficoides)
and their bearing upon the question of the formation of Coal-Beds.
Midland Naturalist, vol. xii. p. 25.
Greville, R. K. (31) See Hooker, W. J. and R. K. Greville.
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environs des villages Troitskoie et Longanskoie dans le bassin du
Donetz. Bull. Com. Géol. St. Pétersbourg, tome xvii.
Gwynne-Vaughan, D. T. (01) Observations on the anatomy of solenostelic
ferns. Annals Bot. vol. xiv. p. 71.
—— (03) Observations &c. Ibid. vol. xvii. p. 689.
—— (05) On the anatomy of Archangiopteris Henryi and other
Marattiaceae. Annals Bot. vol. xix. p. 259.
—— (07–09) See Kidston, R. and D. T. Gwynne-Vaughan.
—— (08) On the real nature of the Tracheae in the ferns. Annals Bot. vol.
xxii. p. 517.
—— and R. Kidston. (08) On the origin of the adaxially curved leaf-trace
in the Filicales. Proc. R. Soc. Edinb. vol. xxviii. pt. vi. p. 433.
Hall, Kate M. (91) See Jennings, A. Vaughan, and Kate M. Hall.
Halle, T. G. (07) Einige krautartige Lycopodiaceen Paläozoischen und
Mesozoischen Alters. Arkiv Bot. Bd. vii. No. 5.
Hannig, E. (98) Ueber die Staubgrübchen auf den Stämmen und
Blattstielen der Cyathaeaceen und Marattiaceen. Bot. Zeit. p. 9.
Harvey-Gibson, R. J. (94) Contributions towards a knowledge of the
anatomy of the genus Selaginella, Spr. Annals Bot. vol. viii. p. 133.
—— (96) Contributions &c. Ibid. vol. x. p. 77.
—— (97) Contributions &c. Ibid. vol. xi. p. 123.
cxliii. p. 664.
—— (08) Sur les organes et la mode de végétation des Neuroptéridées et
autres Ptéridospermes. Compt. Rend. clxvi. p. 1241.
Gresley, W. S. (89) Note on further discoveries of Stigmaria (? ficoides)
and their bearing upon the question of the formation of Coal-Beds.
Midland Naturalist, vol. xii. p. 25.
Greville, R. K. (31) See Hooker, W. J. and R. K. Greville.
Grigoriew, N. (98) Sur la flore paléozoique supérieure recueillie aux
environs des villages Troitskoie et Longanskoie dans le bassin du
Donetz. Bull. Com. Géol. St. Pétersbourg, tome xvii.
Gwynne-Vaughan, D. T. (01) Observations on the anatomy of solenostelic
ferns. Annals Bot. vol. xiv. p. 71.
—— (03) Observations &c. Ibid. vol. xvii. p. 689.
—— (05) On the anatomy of Archangiopteris Henryi and other
Marattiaceae. Annals Bot. vol. xix. p. 259.
—— (07–09) See Kidston, R. and D. T. Gwynne-Vaughan.
—— (08) On the real nature of the Tracheae in the ferns. Annals Bot. vol.
xxii. p. 517.
—— and R. Kidston. (08) On the origin of the adaxially curved leaf-trace
in the Filicales. Proc. R. Soc. Edinb. vol. xxviii. pt. vi. p. 433.
Hall, Kate M. (91) See Jennings, A. Vaughan, and Kate M. Hall.
Halle, T. G. (07) Einige krautartige Lycopodiaceen Paläozoischen und
Mesozoischen Alters. Arkiv Bot. Bd. vii. No. 5.
Hannig, E. (98) Ueber die Staubgrübchen auf den Stämmen und
Blattstielen der Cyathaeaceen und Marattiaceen. Bot. Zeit. p. 9.
Harvey-Gibson, R. J. (94) Contributions towards a knowledge of the
anatomy of the genus Selaginella, Spr. Annals Bot. vol. viii. p. 133.
—— (96) Contributions &c. Ibid. vol. x. p. 77.
—— (97) Contributions &c. Ibid. vol. xi. p. 123.
Page 641
—— (02) Contributions &c. Ibid. vol. xvi. p. 449.
Haughton, S. (59) On Cyclostigma, a new genus of fossil plants from the
Old Red Sandstone of Kiltorkan, W. Kilkenny. Journ. Roy. Dublin Soc.
vol. ii. p. 407.
Hawkshaw, J. (42) Description of the fossil trees found in the excavations
for the Manchester and Bolton railway. Trans. Geol. Soc. [2] vol. vi. p.
173.
Hayden, H. H. (07) The stratigraphical position of the Gangamopteris beds
of Kashmir. Rec. Geol. Surv. India, vol. xxxvi. pt. i.
Heer, O. (71) Fossile Flora der Bären Inseln. Flor. Foss. Arct. vol. ii.
—— (74) Die Kreideflora der Arctischen Zone. K. Svensk. Vetenskaps-
Akad. Hand. Bd. xii. [Flor. Foss. Arct. vol. iii. 1875.]
—— (75) Flora Fossilis Arctica, vol. iii.
—— (76) Jura-Flora Ostsibiriens und des Amurlandes. Ibid. vol. iv. [ii].
—— (80) Nachträge zur fossilen Flora Grönlands. K. Svensk. Vetenskaps-
Akad. Hand. Bd. xviii. [Flor. Foss. Arct. vol. vi. 1882.]
—— (82) Die Fossile-Flora Grönlands. Flor. Foss. Arct. vol. vi.
Hegelmaier, F. (72) Zur Morphologie der Gattung Lycopodium. Bot. Zeit.
1872, p. 773.
Hick, T. (93) On a new fossil plant from the Lower Coal-Measures. Journ.
Linn. Soc. vol. xxix. p. 86.
—— (932) Supplementary note on a new fossil plant. Ibid. p. 216.
—— (96) On Rachiopteris cylindrica. Mem. Proc. Manchester Lit. Phil.
Soc. vol. xli. pt. i.
Hieronymus, G. (02) Selaginellaceae. Die Natürlichen Pflanzenfamilien.
Engler and Prantl, Teil i. Abt. 4, p. 621.
Hill, T. G. (00) See Scott, D. H. and T. G. Hill.
—— (02) See Farmer, J. B. and T. G. Hill.
—— (04) On the presence of a parichnos in recent plants. Annals Bot. vol.
xviii. p. 654.
Haughton, S. (59) On Cyclostigma, a new genus of fossil plants from the
Old Red Sandstone of Kiltorkan, W. Kilkenny. Journ. Roy. Dublin Soc.
vol. ii. p. 407.
Hawkshaw, J. (42) Description of the fossil trees found in the excavations
for the Manchester and Bolton railway. Trans. Geol. Soc. [2] vol. vi. p.
173.
Hayden, H. H. (07) The stratigraphical position of the Gangamopteris beds
of Kashmir. Rec. Geol. Surv. India, vol. xxxvi. pt. i.
Heer, O. (71) Fossile Flora der Bären Inseln. Flor. Foss. Arct. vol. ii.
—— (74) Die Kreideflora der Arctischen Zone. K. Svensk. Vetenskaps-
Akad. Hand. Bd. xii. [Flor. Foss. Arct. vol. iii. 1875.]
—— (75) Flora Fossilis Arctica, vol. iii.
—— (76) Jura-Flora Ostsibiriens und des Amurlandes. Ibid. vol. iv. [ii].
—— (80) Nachträge zur fossilen Flora Grönlands. K. Svensk. Vetenskaps-
Akad. Hand. Bd. xviii. [Flor. Foss. Arct. vol. vi. 1882.]
—— (82) Die Fossile-Flora Grönlands. Flor. Foss. Arct. vol. vi.
Hegelmaier, F. (72) Zur Morphologie der Gattung Lycopodium. Bot. Zeit.
1872, p. 773.
Hick, T. (93) On a new fossil plant from the Lower Coal-Measures. Journ.
Linn. Soc. vol. xxix. p. 86.
—— (932) Supplementary note on a new fossil plant. Ibid. p. 216.
—— (96) On Rachiopteris cylindrica. Mem. Proc. Manchester Lit. Phil.
Soc. vol. xli. pt. i.
Hieronymus, G. (02) Selaginellaceae. Die Natürlichen Pflanzenfamilien.
Engler and Prantl, Teil i. Abt. 4, p. 621.
Hill, T. G. (00) See Scott, D. H. and T. G. Hill.
—— (02) See Farmer, J. B. and T. G. Hill.
—— (04) On the presence of a parichnos in recent plants. Annals Bot. vol.
xviii. p. 654.
Page 642
—— (06) On the presence of a parichnos in recent plants. Ibid. vol. xx. p.
267.
Hofmeister, W. (62) On the germination, development, and fructification of
the Higher Cryptogamia, and on the fructification of the Coniferae.
Ray Soc. 1862.
Hollick, A. (94) Fossil Salvinias, including description of a new species.
Torrey Bot. Club, vol. xxi. No. 6, p. 253.
—— (04) Additions to the Palaeobotany of the Cretaceous Formation on
Long Island. Bull. New York Bot. Gard. vol. iii. p. 403.
—— and E. C. Jeffrey. (09) Studies of Cretaceous coniferous remains from
Kreischerville, New York. Mem. New York Bot. Gard. vol. iii.
Hooker, Sir J. D. (48) On the vegetation of the Carboniferous Period, as
compared with that of the present day. Mem. Geol. Soc. Great Britain,
vol. ii. pt. ii. p. 387.
—— (482) Remarks on the structure and affinities of some Lepidostrobi.
Ibid. p. 440.
—— (59) Stangeria paradoxa. Bot. Mag. Tab. 5121.
Hooker, Sir W. J. and J. G. Baker. (68) Synopsis Filicum. London.
Hooker, Sir W. J. and R. K. Greville. (31) Icones Filicum. Vol. ii. London.
Hosius and von der Marck. (80) Die Flora der Westfälischen
Kreideformation. Palaeont. Bd. xxvi. p. 127.
Hovelacque, M. (92) Recherches sur le Lepidodendron selaginoides,
Sternb. Mém. Soc. Linn. Normandie, vol. xvii.
Hudson, W. H. (92) The Naturalist in La Plata. London.
Jack, R. L. and R. Etheridge. (92) The geology and palæontology of
Queensland and New Guinea. Brisbane.
Jahn, J. J. (03) Ueber die Étage H. im mittelböhmischen Devon. Verh.
Reichsanst. Wien, No. 4, p. 73.
Jeffrey, E. C. (98) The morphology of the central cylinder in vascular
plants. Brit. Assoc. Rep. (Toronto Meeting), p. 869.
267.
Hofmeister, W. (62) On the germination, development, and fructification of
the Higher Cryptogamia, and on the fructification of the Coniferae.
Ray Soc. 1862.
Hollick, A. (94) Fossil Salvinias, including description of a new species.
Torrey Bot. Club, vol. xxi. No. 6, p. 253.
—— (04) Additions to the Palaeobotany of the Cretaceous Formation on
Long Island. Bull. New York Bot. Gard. vol. iii. p. 403.
—— and E. C. Jeffrey. (09) Studies of Cretaceous coniferous remains from
Kreischerville, New York. Mem. New York Bot. Gard. vol. iii.
Hooker, Sir J. D. (48) On the vegetation of the Carboniferous Period, as
compared with that of the present day. Mem. Geol. Soc. Great Britain,
vol. ii. pt. ii. p. 387.
—— (482) Remarks on the structure and affinities of some Lepidostrobi.
Ibid. p. 440.
—— (59) Stangeria paradoxa. Bot. Mag. Tab. 5121.
Hooker, Sir W. J. and J. G. Baker. (68) Synopsis Filicum. London.
Hooker, Sir W. J. and R. K. Greville. (31) Icones Filicum. Vol. ii. London.
Hosius and von der Marck. (80) Die Flora der Westfälischen
Kreideformation. Palaeont. Bd. xxvi. p. 127.
Hovelacque, M. (92) Recherches sur le Lepidodendron selaginoides,
Sternb. Mém. Soc. Linn. Normandie, vol. xvii.
Hudson, W. H. (92) The Naturalist in La Plata. London.
Jack, R. L. and R. Etheridge. (92) The geology and palæontology of
Queensland and New Guinea. Brisbane.
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Reichsanst. Wien, No. 4, p. 73.
Jeffrey, E. C. (98) The morphology of the central cylinder in vascular
plants. Brit. Assoc. Rep. (Toronto Meeting), p. 869.
Page 643
—— (982) The Gametophyte of Botrychium virginianum. Trans. Canad.
Inst. vol. v. p. 265.
—— (00) The morphology of the central cylinder in the Angiosperms. Ibid.
vol. vi. p. 599.
—— (03) The structure and development of the stem in the Pteridophyta
and Gymnosperms. Phil. Trans. R. Soc. vol. cxcv. p. 119.
—— (09) See Hollick, A. and E. C. Jeffrey.
Jennings, A. Vaughan and Kate M. Hall. (91) Notes on the structure of
Tmesipteris. Proc. R. Irish Acad. [3] vol. ii. p. 1.
Jones, C. E. (05) The morphology and anatomy of the stem of the genus
Lycopodium. Trans. Linn. Soc. vol. vii. p. 15.
Jordan, Rose. (03) On some peculiar tyloses in Cucumis sativus. New
Phytologist, vol. ii. p. 208.
Karsten, G. (95) Morphologische und biologische Untersuchungen über
einige Epiphytenformen der Molukken. Ann. Jard. Buitenzorg, vol. xii.
p. 117.
Kidston, R. (82) On the fructification of Eusphenopteris tenella and
Sphenopteris microcarpa. R. Physc. Soc. Edinb. vol. vii.
—— (83) Report on the fossil plants collected by the Geological Survey of
Scotland in Eskdale and Liddesdale. Trans. R. Soc. Edinburgh, vol.
xxx. p. 531.
—— (84) On a new species of Lycopodites, Goldenberg (L. Stockii), from
the Calciferous Sandstone Series of Scotland. Ann. Mag. Nat. Hist. [5]
vol. xiv. p. 111.
—— (842) On the fructification of Zeilleria (Sphenopteris) delicatula,
Sternb. sp.; with remarks on Urnatopteris (Sphenopteris) tenella,
Brongnt., and Hymenophyllites (Sphenopteris) quadridactylites,
Gutbier sp. Quart. Journ. Geol. Soc. vol. xl. p. 590.
—— (85) On the relationship of Ulodendron, Lindley and Hutton, to
Lepidodendron, Sternberg; Bothrodendron, Lindley and Hutton;
Sigillaria, Brongniart; and Rhytidodendron, Boulay. Ann. Mag. Nat.
Hist. vol. xvi. p. 123.
Inst. vol. v. p. 265.
—— (00) The morphology of the central cylinder in the Angiosperms. Ibid.
vol. vi. p. 599.
—— (03) The structure and development of the stem in the Pteridophyta
and Gymnosperms. Phil. Trans. R. Soc. vol. cxcv. p. 119.
—— (09) See Hollick, A. and E. C. Jeffrey.
Jennings, A. Vaughan and Kate M. Hall. (91) Notes on the structure of
Tmesipteris. Proc. R. Irish Acad. [3] vol. ii. p. 1.
Jones, C. E. (05) The morphology and anatomy of the stem of the genus
Lycopodium. Trans. Linn. Soc. vol. vii. p. 15.
Jordan, Rose. (03) On some peculiar tyloses in Cucumis sativus. New
Phytologist, vol. ii. p. 208.
Karsten, G. (95) Morphologische und biologische Untersuchungen über
einige Epiphytenformen der Molukken. Ann. Jard. Buitenzorg, vol. xii.
p. 117.
Kidston, R. (82) On the fructification of Eusphenopteris tenella and
Sphenopteris microcarpa. R. Physc. Soc. Edinb. vol. vii.
—— (83) Report on the fossil plants collected by the Geological Survey of
Scotland in Eskdale and Liddesdale. Trans. R. Soc. Edinburgh, vol.
xxx. p. 531.
—— (84) On a new species of Lycopodites, Goldenberg (L. Stockii), from
the Calciferous Sandstone Series of Scotland. Ann. Mag. Nat. Hist. [5]
vol. xiv. p. 111.
—— (842) On the fructification of Zeilleria (Sphenopteris) delicatula,
Sternb. sp.; with remarks on Urnatopteris (Sphenopteris) tenella,
Brongnt., and Hymenophyllites (Sphenopteris) quadridactylites,
Gutbier sp. Quart. Journ. Geol. Soc. vol. xl. p. 590.
—— (85) On the relationship of Ulodendron, Lindley and Hutton, to
Lepidodendron, Sternberg; Bothrodendron, Lindley and Hutton;
Sigillaria, Brongniart; and Rhytidodendron, Boulay. Ann. Mag. Nat.
Hist. vol. xvi. p. 123.
Page 644
—— (862) On a new species of Psilotites from the Lanarkshire Coal-field.
Ann. Mag. Nat. Hist. 1886, p. 494.
—— (863) On the occurrence of Lycopodites Vanuxemi, Göppert, in Britain,
with remarks on its affinities. Journ. Linn. Soc. vol. xxi. p. 560.
—— (864) Notes on some fossil plants collected by Mr R. Dunlop, Airdrie,
from the Lanarkshire Coal-field. Trans. Geol. Soc. Glasgow, vol. viii.
p. 47.
—— (87) On the fructification of some ferns from the Carboniferous
formation. Trans. R. Soc. Edinb. vol. xxxiii. pt. i.
—— (88) See Bennie, J. and R. Kidston.
—— (88) On the fossil flora of the Radstock series of the Somerset and
Bristol Coal-field (Upper Coal-Measures). Part I. Trans. R. Soc. Edinb.
vol. xxxiii. pt. 2.
—— (882) On the fructification and affinities of Archaeopteris hibernica,
Forbes sp. Ann. Mag. Nat. Hist. [6] vol. ii.
—— (89) On the fossil plants in the Ravenhead Collection in the Free
Library and Museum, Liverpool. Trans. R. Soc. Edinb. vol. xxxv. pt. ii.
—— (892) Additional notes on some British Carboniferous Lycopods. Ann.
Mag. Nat. Hist. vol. iv. p. 60.
—— (893) On some fossil plants from Teilia quarry, Gwaenysgor, near
Prestatyn, Flintshire. Trans. R. Soc. Edinb. vol. xxxv. pt. ii.
—— (91) On the fructification of Sphenophyllum trichomatosum, Stern.
from the Yorkshire Coal-field. Proc. R. Soc. Edinb. vol. xi. p. 56.
—— (912) On the fructification and internal structure of Carboniferous
ferns in their relation to those of existing genera. Trans. Geol. Soc.
Glasgow, vol. ix. pt. i.
—— (913) On the Fossil Flora of the Staffordshire Coal-fields. II. Trans. R.
Soc. Edinb. vol. xxxvi. p. 63.
—— (93) On Lepidophloios, and on the British species of the genus. Trans.
R. Soc. Edinb. vol. xxxvii. pt. iii. p. 529.
Ann. Mag. Nat. Hist. 1886, p. 494.
—— (863) On the occurrence of Lycopodites Vanuxemi, Göppert, in Britain,
with remarks on its affinities. Journ. Linn. Soc. vol. xxi. p. 560.
—— (864) Notes on some fossil plants collected by Mr R. Dunlop, Airdrie,
from the Lanarkshire Coal-field. Trans. Geol. Soc. Glasgow, vol. viii.
p. 47.
—— (87) On the fructification of some ferns from the Carboniferous
formation. Trans. R. Soc. Edinb. vol. xxxiii. pt. i.
—— (88) See Bennie, J. and R. Kidston.
—— (88) On the fossil flora of the Radstock series of the Somerset and
Bristol Coal-field (Upper Coal-Measures). Part I. Trans. R. Soc. Edinb.
vol. xxxiii. pt. 2.
—— (882) On the fructification and affinities of Archaeopteris hibernica,
Forbes sp. Ann. Mag. Nat. Hist. [6] vol. ii.
—— (89) On the fossil plants in the Ravenhead Collection in the Free
Library and Museum, Liverpool. Trans. R. Soc. Edinb. vol. xxxv. pt. ii.
—— (892) Additional notes on some British Carboniferous Lycopods. Ann.
Mag. Nat. Hist. vol. iv. p. 60.
—— (893) On some fossil plants from Teilia quarry, Gwaenysgor, near
Prestatyn, Flintshire. Trans. R. Soc. Edinb. vol. xxxv. pt. ii.
—— (91) On the fructification of Sphenophyllum trichomatosum, Stern.
from the Yorkshire Coal-field. Proc. R. Soc. Edinb. vol. xi. p. 56.
—— (912) On the fructification and internal structure of Carboniferous
ferns in their relation to those of existing genera. Trans. Geol. Soc.
Glasgow, vol. ix. pt. i.
—— (913) On the Fossil Flora of the Staffordshire Coal-fields. II. Trans. R.
Soc. Edinb. vol. xxxvi. p. 63.
—— (93) On Lepidophloios, and on the British species of the genus. Trans.
R. Soc. Edinb. vol. xxxvii. pt. iii. p. 529.
Page 645
—— (94) On the various divisions of British Carboniferous rocks as
determined by their fossil flora. R. Physc. Soc. Edinb. vol. xii. p. 183.
—— (96) On the Fossil Flora of the Yorkshire Coal-fields. I. Trans. R. Soc.
Edinb. vol. xxxviii. p. 203.
—— (97) On the Fossil Flora of the Yorkshire Coal-fields. II. Trans. R. Soc.
Edinb. vol. xxxix. pt. i. p. 33.
—— (01) Carboniferous Lycopods and Sphenophylls. Trans. Nat. Hist. Soc.
Glasgow, vol. vi. pt. i. p. 25.
—— (012) The flora of the Carboniferous Period. Proc. Yorks. Geol. Polyt.
Soc. vol. xiv. pt. ii.
—— (02) The flora &c. Second Paper. Ibid. vol. xiv. pt. iii. p. 344.
—— (03) The fossil plants of the Carboniferous rocks of Canonbie,
Dumfriesshire, and of parts of Cumberland and Northumberland.
Trans. R. Soc. Edinb. vol. xl. pt. iv. p. 741.
—— (05) On the internal structure of Sigillaria elegans of Brongniart’s
“Histoire des Végétaux Fossiles.” Ibid. vol. xli. pt. iii. p. 533.
—— (052) On the fructification of Neuropteris heterophylla. Trans. R. Soc.
London, vol. cxcvii. p. 1.
—— (06) On the microsporangia of the Pteridospermeae, with remarks on
their relationship to existing Ferns. Phil. Trans. R. Soc. vol. cxcviii. p.
413.
—— (07) Note on a new species of Lepidodendron from Pettycur (L.
Pettycurense). Proc. R. Soc. Edinb. 1906–07, p. 207.
—— (072) Preliminary note on the internal structure of Sigillaria
mammillaris Brongniart and S. scutellata Brongniart. Ibid. vol. xxvii.
p. 203.
—— (08) On a new species of Dineuron and of Botryopteris from Pettycur,
Fife. Trans. R. Soc. Edinb. vol. xlvi. pt. ii. p. 361.
—— (08) See Gwynne-Vaughan, D. T. and R. Kidston.
Kidston, R. and D. T. Gwynne-Vaughan. (07) On the fossil Osmundaceae.
Pt. I. Trans. R. Soc. Edinb. vol. xlv. pt. iii. p. 759.
determined by their fossil flora. R. Physc. Soc. Edinb. vol. xii. p. 183.
—— (96) On the Fossil Flora of the Yorkshire Coal-fields. I. Trans. R. Soc.
Edinb. vol. xxxviii. p. 203.
—— (97) On the Fossil Flora of the Yorkshire Coal-fields. II. Trans. R. Soc.
Edinb. vol. xxxix. pt. i. p. 33.
—— (01) Carboniferous Lycopods and Sphenophylls. Trans. Nat. Hist. Soc.
Glasgow, vol. vi. pt. i. p. 25.
—— (012) The flora of the Carboniferous Period. Proc. Yorks. Geol. Polyt.
Soc. vol. xiv. pt. ii.
—— (02) The flora &c. Second Paper. Ibid. vol. xiv. pt. iii. p. 344.
—— (03) The fossil plants of the Carboniferous rocks of Canonbie,
Dumfriesshire, and of parts of Cumberland and Northumberland.
Trans. R. Soc. Edinb. vol. xl. pt. iv. p. 741.
—— (05) On the internal structure of Sigillaria elegans of Brongniart’s
“Histoire des Végétaux Fossiles.” Ibid. vol. xli. pt. iii. p. 533.
—— (052) On the fructification of Neuropteris heterophylla. Trans. R. Soc.
London, vol. cxcvii. p. 1.
—— (06) On the microsporangia of the Pteridospermeae, with remarks on
their relationship to existing Ferns. Phil. Trans. R. Soc. vol. cxcviii. p.
413.
—— (07) Note on a new species of Lepidodendron from Pettycur (L.
Pettycurense). Proc. R. Soc. Edinb. 1906–07, p. 207.
—— (072) Preliminary note on the internal structure of Sigillaria
mammillaris Brongniart and S. scutellata Brongniart. Ibid. vol. xxvii.
p. 203.
—— (08) On a new species of Dineuron and of Botryopteris from Pettycur,
Fife. Trans. R. Soc. Edinb. vol. xlvi. pt. ii. p. 361.
—— (08) See Gwynne-Vaughan, D. T. and R. Kidston.
Kidston, R. and D. T. Gwynne-Vaughan. (07) On the fossil Osmundaceae.
Pt. I. Trans. R. Soc. Edinb. vol. xlv. pt. iii. p. 759.
Page 646
—— (08) Ibid. pt. II. loc. cit. vol. xlvi. pt. ii. p. 213.
—— (09) Ibid. pt. III. loc. cit. vol. xlvi. pt. iii. p. 651.
Kitchin, F. L. (08) The invertebrate fauna and palaeontological relations of
the Uitenhage series. Ann. S. African Mus. vol. vii. pt. ii.
Knowlton, F. H. (98) A catalogue of the Cretaceous and Tertiary plants of
North America. Bull. U. S. Geol. Surv. No. 152.
—— (99) Fossil flora of the Yellowstone National Park. U. S. Geol. Surv.
Mem. xxxiii. pt. ii.
—— (02) Report on a small collection of fossil plants from the vicinity of
Porcupine Butte, Montana. Bull. Torrey Bot. Club, vol. xxix.
Kny, L. (75) Die Entwickelung der Parkeriaceen dargestellt an Ceratopteris
thalictroides, Brongniart. Nova Acta K. Leop.-Car. Deutsch. Akad.
Naturf. vol. xxxvii.
Koehne, W. (04) Sigillarienstämme, Unterscheidungsmerkmale, Arten,
Geologische Verbreitung &c. Abh. K. Preuss. Geol. Landes. [N. F.],
Heft xliii.
Krasser, F. (95) Kreidepflanzen von Lesina. Jahrb. K.-K. Geol. Reichs. Bd.
xlv. p. 37.
—— (96) Beiträge zur Kenntniss der Fossilen Kreideflora von Kunstadt in
Mähren. Beit. Paläont. Geol. Österreich.-Ung. und des Orients, Bd. x.
Heft 3.
—— (00) Die von W. A. Obrutschew in China und Centralasien 1893–94
gesammelten fossilen Pflanzen. Denksch. K. Akad. Wiss. Wien, Bd.
lxx.
—— (06) Ueber die fossile Kreideflora von Grünbach in Niederösterreich.
Sitzb. K. Akad. Wiss. Wien (Anz. iii.).
—— (09) Die Diagnosen der von D. Stur in der obertriadischen Flora der
Lunzerschichten als Marattiaceenarten unterschiedenen Farne. Sitz.
Kais. Akad. Wiss. Wien, Bd. cxviii. Abt. i.
Kubart, B. (09) Untersuchungen über die Flora des Ostrau-Karwiner
Kohlenbeckens. I. Die Spore von Spencerites membranaceus n. sp.
—— (09) Ibid. pt. III. loc. cit. vol. xlvi. pt. iii. p. 651.
Kitchin, F. L. (08) The invertebrate fauna and palaeontological relations of
the Uitenhage series. Ann. S. African Mus. vol. vii. pt. ii.
Knowlton, F. H. (98) A catalogue of the Cretaceous and Tertiary plants of
North America. Bull. U. S. Geol. Surv. No. 152.
—— (99) Fossil flora of the Yellowstone National Park. U. S. Geol. Surv.
Mem. xxxiii. pt. ii.
—— (02) Report on a small collection of fossil plants from the vicinity of
Porcupine Butte, Montana. Bull. Torrey Bot. Club, vol. xxix.
Kny, L. (75) Die Entwickelung der Parkeriaceen dargestellt an Ceratopteris
thalictroides, Brongniart. Nova Acta K. Leop.-Car. Deutsch. Akad.
Naturf. vol. xxxvii.
Koehne, W. (04) Sigillarienstämme, Unterscheidungsmerkmale, Arten,
Geologische Verbreitung &c. Abh. K. Preuss. Geol. Landes. [N. F.],
Heft xliii.
Krasser, F. (95) Kreidepflanzen von Lesina. Jahrb. K.-K. Geol. Reichs. Bd.
xlv. p. 37.
—— (96) Beiträge zur Kenntniss der Fossilen Kreideflora von Kunstadt in
Mähren. Beit. Paläont. Geol. Österreich.-Ung. und des Orients, Bd. x.
Heft 3.
—— (00) Die von W. A. Obrutschew in China und Centralasien 1893–94
gesammelten fossilen Pflanzen. Denksch. K. Akad. Wiss. Wien, Bd.
lxx.
—— (06) Ueber die fossile Kreideflora von Grünbach in Niederösterreich.
Sitzb. K. Akad. Wiss. Wien (Anz. iii.).
—— (09) Die Diagnosen der von D. Stur in der obertriadischen Flora der
Lunzerschichten als Marattiaceenarten unterschiedenen Farne. Sitz.
Kais. Akad. Wiss. Wien, Bd. cxviii. Abt. i.
Kubart, B. (09) Untersuchungen über die Flora des Ostrau-Karwiner
Kohlenbeckens. I. Die Spore von Spencerites membranaceus n. sp.
Page 647
Denksch. K. Akad. Wiss. Wien, Bd. lxxxv.
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—— (08) Preliminary statement on the morphology of the cone of
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Mohl, H. von. (40) Ueber den Bau des Stammes von Isoetes lacustris.
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Morris, J. (40) Ex Prestwich’s, J., Memoir on the Geology of Coalbrook
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—— (45) See Strzelecki, Count.
—— (63) See Oldham, T. and J. Morris.
Motelay, L. and Vendryès. (82) Monographie der Isoetaceae. Actes Soc.
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Münster, G. Graf zu. (42) Beiträge zur Petrefacten-Kunde. Heft 5.
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Nathorst, A. G. (78) Beiträge zur fossilen Flora Schwedens. Ueber einige
Rhätische Pflanzen von Pålsjö in Schonen. Stuttgart.
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Lunds Univ. Årsskrift, N.F. Bd. ii. No. 8.
Linnaea, vol. xiv.
Morris, J. (40) Ex Prestwich’s, J., Memoir on the Geology of Coalbrook
Dale. Trans. Geol. Soc. vol. v. p. 413.
—— (45) See Strzelecki, Count.
—— (63) See Oldham, T. and J. Morris.
Motelay, L. and Vendryès. (82) Monographie der Isoetaceae. Actes Soc.
Linn. Bordeaux, Tom. xxxvi. p. 309.
Münster, G. Graf zu. (42) Beiträge zur Petrefacten-Kunde. Heft 5.
Bayreuth.
Murchison, R. I., J. Buchman, and H. E. Strickland. (45) Outline of the
Geology of the neighbourhood of Cheltenham. London.
Murchison, R., E. de Verneuil, and Count A. Keyserling. (45) Géologie
de la Russie d’Europe. Vol. ii. London and Paris.
Nathorst, A. G. (78) Beiträge zur fossilen Flora Schwedens. Ueber einige
Rhätische Pflanzen von Pålsjö in Schonen. Stuttgart.
—— (782) Om Floran i Skånes kolförande Bildningar. Sver. Geol. Unders.
Ser. C.
—— (90) Ueber das angebliche Vorkommen von Geschieben des
Hörsandsteins in den norddeutschen Diluvialablagerungen. Arch. Ver.
Freund. Nat. Mecklenb., Jahr. xliv.
—— (02) Zur fossilen Flora der Polarländer. i. Zur Oberdevonischen Flora
der Bären-Insel. K. Svensk. Vetenskaps-Akad. Hand. Bd. xxxvi. No. 3.
—— (022) Beiträge zur Kenntniss Mesozoischen Cycadophyten. Ibid. Bd.
xxxvi. No. 4.
—— (04) Die Oberdevonische Flora des Ellesmere Landes. Rep. Second
Norwegian Arctic Exp. in the Fram (1898–02), No. 1.
—— (042) Sur la flore fossile antarctique. Compt. Rend. (June 6.)
—— (06) Om Några Ginkgoväxter från Kolgrufvorna vid Stabbarp i Skåne.
Lunds Univ. Årsskrift, N.F. Bd. ii. No. 8.
Page 650
—— (062) Bemerkungen über Clathropteris meniscoides, Brongn., und
Rhizomopteris cruciata, Nath. K. Svensk. Vetenskaps-Akad. Hand. Bd.
xli. No. 2.
—— (063) Ueber Dictyophyllum und Camptopteris spiralis. Ibid. No. 5.
—— (07) Ueber die Anwendung von Kollodium-Abdrücken bei der
Untersuchung fossiler Pflanzen. Arkiv Bot., Stockholm, Bd. vii. No. 4.
—— (072) Ueber Thaumatopteris Schenki. K. Svensk. Vetenskaps-Akad.
Hand. Bd. xlii. No. 3.
—— (08) Paläobotanisch. Mitteilungen, iii. Ibid. Bd. xliii. No. 3.
Newberry, J. S. (91) The Flora of the Great Falls Coal-Field, Montana.
Amer. Journ. Sci. vol. xli. p. 191.
Newton, R. Bullen. (09) Fossils from the Nubian Sandstone of Egypt.
Geol. Mag. vol. vi. p. 352.
Oldham, R. D. (97) On a plant of Glossopteris with part of the rhizome
attached, and on the structure of Vertebraria. Rec. Geol. Surv. India,
vol. xxx. pt. i. p. 45.
Oldham, T. and J. Morris. (63) Fossil Flora of the Gondwana system. Vol.
i. pt. i. Fossil Flora of the Rajmahal series in the Rajmahal Hills. Mem.
Geol. Surv. India [2], Calcutta.
Oliver, F. W. (02) A vascular Sporangium. New Phytologist, vol. i. p. 60.
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Sphenopteris affinis and on Staphylopteris (?) Peachii of Etheridge and
Balfour, a genus of plants new to British rocks. Quart. Journ. Geol.
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Pelourde, F. (08) Recherches sur la position systématique des plantes
fossiles dont les tiges out été appelées Psaronius, Psaroniocaulon,
Caulopteris. Bull. Soc. bot. France [4], tome viii.
—— (082) Recherches comparatives sur la structure de la racine chez un
certain nombre de Psaronius. Ibid. p. 352.
Rhizomopteris cruciata, Nath. K. Svensk. Vetenskaps-Akad. Hand. Bd.
xli. No. 2.
—— (063) Ueber Dictyophyllum und Camptopteris spiralis. Ibid. No. 5.
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Untersuchung fossiler Pflanzen. Arkiv Bot., Stockholm, Bd. vii. No. 4.
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Hand. Bd. xlii. No. 3.
—— (08) Paläobotanisch. Mitteilungen, iii. Ibid. Bd. xliii. No. 3.
Newberry, J. S. (91) The Flora of the Great Falls Coal-Field, Montana.
Amer. Journ. Sci. vol. xli. p. 191.
Newton, R. Bullen. (09) Fossils from the Nubian Sandstone of Egypt.
Geol. Mag. vol. vi. p. 352.
Oldham, R. D. (97) On a plant of Glossopteris with part of the rhizome
attached, and on the structure of Vertebraria. Rec. Geol. Surv. India,
vol. xxx. pt. i. p. 45.
Oldham, T. and J. Morris. (63) Fossil Flora of the Gondwana system. Vol.
i. pt. i. Fossil Flora of the Rajmahal series in the Rajmahal Hills. Mem.
Geol. Surv. India [2], Calcutta.
Oliver, F. W. (02) A vascular Sporangium. New Phytologist, vol. i. p. 60.
—— (04) On the structure and affinities of Stephanospermum, Brongn., a
genus of fossil Gymnosperm seeds. Trans. Linn. Soc. vol. vi. pt. 8.
Peach, C. W. (78) On the circinate vernation, fructification, and varieties of
Sphenopteris affinis and on Staphylopteris (?) Peachii of Etheridge and
Balfour, a genus of plants new to British rocks. Quart. Journ. Geol.
Soc. vol. xxxiv. p. 131.
Pelourde, F. (08) Recherches sur la position systématique des plantes
fossiles dont les tiges out été appelées Psaronius, Psaroniocaulon,
Caulopteris. Bull. Soc. bot. France [4], tome viii.
—— (082) Recherches comparatives sur la structure de la racine chez un
certain nombre de Psaronius. Ibid. p. 352.
Page 651
—— (09) Recherches comparatives sur la structure des fougères fossiles et
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der beiden Seitennärbchen der Blattnarbe des Lepidodendron-
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—— (933) Eine gewöhnliche Art der Erhaltung von Stigmaria als Beweis
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—— (95) Die Beziehung zwischen dem echt-gabeligen und dem fiederigen
Wedel-Aufbau der Farne. Ber. Deutsch. Bot. Ges. Bd. xiii. Heft 6.
—— (99) Lehrbuch der Pflanzenpalaeontologie. Berlin.
—— (00) Fossile Pflanzen aus Deutsch- und Portugiesisch-Ost-Afrika.
Deutsch-Ost-Afrika, Bd. vii.
vivants. Ann. Sci. nat. vol. x. p. 115.
—— (092) Observations sur un nouveau type de pétiole fossile, le Flicheia
esnostensis. Mém. Soc. d’hist. nat. d’Autun, tome xxi.
Penhallow, D. P. (92) Additional notes on Devonian plants from Scotland.
Canadian Rec. Sci. vol. v. no. 1.
—— (02) Osmundites skidegatensis. Trans. R. Soc. Canada [2], vol. viii.
sect. 4.
Phillips, J. (75) Illustrations of the Geology of Yorkshire, pt. i. The
Yorkshire Coast (edit. 3). London.
Pittman, E. F. (93) See David, E. and E. F. Pittman.
Potonié, H. (89) Der im Lichthof der Königlichen Geologischen
Landesanstalt und Bergakademie aufgestellte Baumstumpf mit Wurzel
aus dem Carbon des Piesberges. Jahrb. K. Preuss. Geol. Landes, p.
246.
—— (91) Bericht. Deutsch. bot. Ges. vol. ix. p. 256.
—— (92) Ueber einige Carbonfarne. Jahrb. K. Preuss. Geol. Landes. 1891.
—— (922) Die den Wasserspalten physiologischentsprechenden Organe bei
fossilen und recenten Farnarten. Sitz.-Ber. Ges. naturforsch. Freunde
zu Berlin. July 19, 1892.
—— (932) Anatomie der beiden “Male” auf dem unteren Wangenpaar und
der beiden Seitennärbchen der Blattnarbe des Lepidodendron-
Blattpolsters. Ber. deutsch. Bot. Ges. Bd. xi. Heft 5, p. 319.
—— (933) Eine gewöhnliche Art der Erhaltung von Stigmaria als Beweis
für die Autochthonie von Carbon-Pflanzen. Zeits. Deutsch. Geol. Ges.
—— (95) Die Beziehung zwischen dem echt-gabeligen und dem fiederigen
Wedel-Aufbau der Farne. Ber. Deutsch. Bot. Ges. Bd. xiii. Heft 6.
—— (99) Lehrbuch der Pflanzenpalaeontologie. Berlin.
—— (00) Fossile Pflanzen aus Deutsch- und Portugiesisch-Ost-Afrika.
Deutsch-Ost-Afrika, Bd. vii.
Page 652
—— (01) Fossile Lycopodiaceae und Selaginellaceae. Engler and Prantl:
Die natürlichen Pflanzenfamilien, Teil i. Abt. iv. p. 715.
—— (012) Die Silur- und die Culm-Flora. Abh. K. Preuss. Geol. Landes.
Heft xxxvi.
—— (02) Ueber die fossilen Filicales &c. Engler and Prantl: Die
natürlichen Pflanzenfamilien, Teil i. Abt. iv. p. 473.
—— (03) Zur Physiologie und Morphologie der fossilen Farn-Aphlebien.
Ber. Deutsch. Bot. Ges. Bd. xxi. Heft 3.
—— (04) Abbildungen und Beschreibungen fossilen Pflanzen-Reste der
Palaeozoischen und Mesozoischen Formationen. Lief. ii. K. Preuss.
Geol. Landes- und Bergakad.
—— (05) Ibid. Lief. iii.
—— (06) Ibid. Lief. iii.
—— (07) Abbildungen und Beschreibungen &c. Lief. v.
Prantl, K. (81) Untersuchungen zur Morphologie der Gefässkryptogamen.
Heft ii. Leipzig.
—— (02) See Engler, A. and K. Prantl.
Pritzel, E. (02) Lycopodiales. Engler and Prantl: Die natürlichen
Pflanzenfamilien, Teil i. Abt. iv. p. 563.
Raciborski, M. (91) Ueber die Osmundaceen und Schizaeaceen der
Juraformation. Engler’s Bot. Jahrb. vol. xiii. p. 1.
Reid, C. (99) The Origin of the British Flora. London.
Reinecke, F. (97) Die Flora der Samoa-Inseln. Engler’s Bot. Jahrb. Bd.
xxiii. p. 237.
Renault, B. (69) Étude sur quelques végétaux silicifiés des environs
d’Autun. Ann. Sci. nat. [5], vol. xii. p. 161.
—— (76) Étude du genre Botryopteris. Ann. Sci. nat. [6], vol. i. p. 220.
—— (76) Étude du genre Myelopteris. Mém. Acad. Sci. l’Instit. France,
Tome xxii.
Die natürlichen Pflanzenfamilien, Teil i. Abt. iv. p. 715.
—— (012) Die Silur- und die Culm-Flora. Abh. K. Preuss. Geol. Landes.
Heft xxxvi.
—— (02) Ueber die fossilen Filicales &c. Engler and Prantl: Die
natürlichen Pflanzenfamilien, Teil i. Abt. iv. p. 473.
—— (03) Zur Physiologie und Morphologie der fossilen Farn-Aphlebien.
Ber. Deutsch. Bot. Ges. Bd. xxi. Heft 3.
—— (04) Abbildungen und Beschreibungen fossilen Pflanzen-Reste der
Palaeozoischen und Mesozoischen Formationen. Lief. ii. K. Preuss.
Geol. Landes- und Bergakad.
—— (05) Ibid. Lief. iii.
—— (06) Ibid. Lief. iii.
—— (07) Abbildungen und Beschreibungen &c. Lief. v.
Prantl, K. (81) Untersuchungen zur Morphologie der Gefässkryptogamen.
Heft ii. Leipzig.
—— (02) See Engler, A. and K. Prantl.
Pritzel, E. (02) Lycopodiales. Engler and Prantl: Die natürlichen
Pflanzenfamilien, Teil i. Abt. iv. p. 563.
Raciborski, M. (91) Ueber die Osmundaceen und Schizaeaceen der
Juraformation. Engler’s Bot. Jahrb. vol. xiii. p. 1.
Reid, C. (99) The Origin of the British Flora. London.
Reinecke, F. (97) Die Flora der Samoa-Inseln. Engler’s Bot. Jahrb. Bd.
xxiii. p. 237.
Renault, B. (69) Étude sur quelques végétaux silicifiés des environs
d’Autun. Ann. Sci. nat. [5], vol. xii. p. 161.
—— (76) Étude du genre Botryopteris. Ann. Sci. nat. [6], vol. i. p. 220.
—— (76) Étude du genre Myelopteris. Mém. Acad. Sci. l’Instit. France,
Tome xxii.
Page 653
—— (79) Structure comparée de quelques tiges de la Flore Carbonifère.
Nouv. Arch. Mus. Paris.
—— (81) Étude sur les Stigmaria. Ann. Sci. Géol. tome xii.
—— (90) Sur une nouvelle Lycopodiacée houillère (Lycopodiopsis Derbyi).
Compt. Rend., April 14.
Renault, B. and C. Grand’Eury. (75) Recherches sur les végétaux
silicifiés d’Autun. Mém. Acad. Paris, vol. xxii.
Renault, B. and A. Roche. (97) Sur une nouveau Diploxylée. Bull. Soc.
d’hist. nat. d’Autun.
Renier, A. (08) Origine raméale des cicatrices Ulodendroides du
Bothrodendron punctatum, Lind. et Hutt. Compt. Rend., June 29.
Reuss, A. E. (46) Die Versteinerungen der Böhmischen Kreideformation.
Stuttgart, 1845–46.
Rhode, J. G. (20) Beiträge zur Pflanzenkunde der Vorwelt. Breslau.
Richter, P. B. (06) Beiträge zur Flora der unteren Kreide Quedlinburgs. Teil
i. Die Gattung Hausmannia, Dunker, und einige seltenere
Pflanzenarten. Leipzig.
Richter, R. (56) See Unger, F. and R. Richter.
Roche, A. (97) See Renault, B. and A. Roche.
Roehl, Major von. (69) Fossile Flora der Steinkohlen Formation
Westphalens. Palaeont. Bd. xviii. p. 1.
Roemer, F. A. (54) Beiträge zur geologischen Kenntniss des nordwestlichen
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Royle, J. F. (33) Illustrations of the Botany and other branches of natural
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Rudolph, K. (05) Psaronien und Marattiaceen. Denksch. Kais. Akad. Wiss.
Wien, Bd. lxxviii.
Sadebeck, H. (02) See Engler, A. and K. Prantl.
Salfeld, H. (07) Fossile Landpflanzen der Rät.- und Juraformation
Südwestdeutschlands. Palaeont. Bd. liv.
Nouv. Arch. Mus. Paris.
—— (81) Étude sur les Stigmaria. Ann. Sci. Géol. tome xii.
—— (90) Sur une nouvelle Lycopodiacée houillère (Lycopodiopsis Derbyi).
Compt. Rend., April 14.
Renault, B. and C. Grand’Eury. (75) Recherches sur les végétaux
silicifiés d’Autun. Mém. Acad. Paris, vol. xxii.
Renault, B. and A. Roche. (97) Sur une nouveau Diploxylée. Bull. Soc.
d’hist. nat. d’Autun.
Renier, A. (08) Origine raméale des cicatrices Ulodendroides du
Bothrodendron punctatum, Lind. et Hutt. Compt. Rend., June 29.
Reuss, A. E. (46) Die Versteinerungen der Böhmischen Kreideformation.
Stuttgart, 1845–46.
Rhode, J. G. (20) Beiträge zur Pflanzenkunde der Vorwelt. Breslau.
Richter, P. B. (06) Beiträge zur Flora der unteren Kreide Quedlinburgs. Teil
i. Die Gattung Hausmannia, Dunker, und einige seltenere
Pflanzenarten. Leipzig.
Richter, R. (56) See Unger, F. and R. Richter.
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Roehl, Major von. (69) Fossile Flora der Steinkohlen Formation
Westphalens. Palaeont. Bd. xviii. p. 1.
Roemer, F. A. (54) Beiträge zur geologischen Kenntniss des nordwestlichen
Harzgebirges. Palaeont. Bd. iii.
Royle, J. F. (33) Illustrations of the Botany and other branches of natural
history of the Himalayan Mountains. London, 1833–39.
Rudolph, K. (05) Psaronien und Marattiaceen. Denksch. Kais. Akad. Wiss.
Wien, Bd. lxxviii.
Sadebeck, H. (02) See Engler, A. and K. Prantl.
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Südwestdeutschlands. Palaeont. Bd. liv.
Page 654
—— (09) Beiträge zur Kenntniss jurassischer Pflanzenreste aus
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en-Provence. Ann. Sci. nat. [7], vol. vii.
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Schenck, H. (93) Beiträge zur Biologie und Anatomie der Lianen. Th. ii.
Jena.
Schenk, A. (71) Beiträge zur Flora der Vorwelt. Die Flora der
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Schmalhausen, J. (77) Die Pflanzenreste aus der Ursa-Stufe im Fluss-
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Petersburg. Tome xxii. p. 278.
—— (94) Ueber Devonische Pflanzen aus dem Donetz-Becken. Mém. Com.
Géol. vol. viii. St Petersburg.
Schuster, J. (08) Zur Kenntniss der Flora der Saarbrücker Schichten und
des pfälzischen Oberrotliegenden. Geognost. Jahresheft, xx. 1907.
Scott, D. H. (96) An introduction to structural botany. Pt. ii. London.
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Norddeutschland. Palaeont. Bd. lvi.
Salter, J. W. (58) On some remains of terrestrial plants in the Old Red
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Saporta, le Marquis de. (88) Dernières adjonctions à la flore fossile d’Aix-
en-Provence. Ann. Sci. nat. [7], vol. vii.
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Saxelby, E. M. (08) The origin of the roots in Lycopodium Selago. Annals
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Schenck, H. (93) Beiträge zur Biologie und Anatomie der Lianen. Th. ii.
Jena.
Schenk, A. (71) Beiträge zur Flora der Vorwelt. Die Flora der
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Bd. xxviii. p. 157.
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Schmalhausen, J. (77) Die Pflanzenreste aus der Ursa-Stufe im Fluss-
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Schuster, J. (08) Zur Kenntniss der Flora der Saarbrücker Schichten und
des pfälzischen Oberrotliegenden. Geognost. Jahresheft, xx. 1907.
Scott, D. H. (96) An introduction to structural botany. Pt. ii. London.
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Carboniferous strata (Calciferous Sandstone series). Phil. Trans. R.
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Page 655
—— (98) On the structure and affinities &c. II. On Spencerites, a new
genus of Lycopodiaceous cones from the Coal-Measures founded on
the Lepidodendron Spenceri of Williamson. Ibid. vol. clxxxix. p. 83.
—— (00) Studies in fossil botany. London.
—— (01) On the structure and affinities &c. IV. The seed-like fructification
of Lepidocarpon, a genus of Lycopodiaceous cones from the
Carboniferous formation. Phil. Trans. R. Soc. vol. cxciv. p. 291.
—— (02) The Old Wood and the New. New Phytologist, vol. i. p. 25.
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18.
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of Britain. Annals Bot. vol. xviii. p. 519.
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Coal-Measures. Phil Trans. R. Soc. vol. cxcviii. p. 17.
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New Phyt. vol. v. p. 170.
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Bot. vol. xx. p. 317.
—— (07) The present position of Palaeozoic botany. Progressus Rei
Botanicae, Bd. i. p. 139.
—— (08) Studies in fossil botany (edit. ii). Vol. i. London.
—— (09) Ibid. Vol. ii.
—— (092) Dr Paul Bertrand on the Zygopterideae. New Phyt. vol. viii. p.
266.
genus of Lycopodiaceous cones from the Coal-Measures founded on
the Lepidodendron Spenceri of Williamson. Ibid. vol. clxxxix. p. 83.
—— (00) Studies in fossil botany. London.
—— (01) On the structure and affinities &c. IV. The seed-like fructification
of Lepidocarpon, a genus of Lycopodiaceous cones from the
Carboniferous formation. Phil. Trans. R. Soc. vol. cxciv. p. 291.
—— (02) The Old Wood and the New. New Phytologist, vol. i. p. 25.
—— (04) Germinating spores in a fossil fern Sporangium. Ibid. vol. iii. p.
18.
—— (042) On the occurrence of Sigillariopsis in the Lower Coal-Measures
of Britain. Annals Bot. vol. xviii. p. 519.
—— (05) On the structure and affinities &c. v. On a new type of
Sphenophyllaceous cone (Sphenophyllum fertile) from the Lower
Coal-Measures. Phil Trans. R. Soc. vol. cxcviii. p. 17.
—— (052) What were the Carboniferous ferns? Journ. R. Micr. Soc. p. 137.
—— (053) The Sporangia of Stauropteris oldhamia. New Phyt. vol. iv. p.
114.
—— (06) On the structure of some Carboniferous ferns. Journ. R. Micr.
Soc. p. 518.
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New Phyt. vol. v. p. 170.
—— (063) The structure of Lepidodendron obovatum, Sternberg. Annals
Bot. vol. xx. p. 317.
—— (07) The present position of Palaeozoic botany. Progressus Rei
Botanicae, Bd. i. p. 139.
—— (08) Studies in fossil botany (edit. ii). Vol. i. London.
—— (09) Ibid. Vol. ii.
—— (092) Dr Paul Bertrand on the Zygopterideae. New Phyt. vol. viii. p.
266.
Page 656
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Watson, D. M. S. (06) On a “fern” synangium from the Lower Coal-
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Page 663
Weber, O. and J. T. Sterzel. (96) Beiträge zur Kenntniss der Medulloseae.
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Weiss, C. E. (69) Fossile Flora der jüngsten Steinkohlenformation und des
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—— (84) Zur Flora der ältesten Schichten des Harzes. Jahrb. K. Preuss.
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—— (86) Ueber eine Buntsandstein Sigillaria und deren nächste
Verwandte. Ibid. 1885.
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Steinkohlengrube. Zeitsch. Deutsch. Geol. Ges.
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Jahrb. Bd. xli. p. 376.
—— and J. Sterzel. (93) Die Sigillarien der Preussischen Steinkohlen und
Rothliegenden Gebiete. K. Preuss. Geol. Landes. [N.F.], Heft 2.
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rootlet probably related to Lepidophloios fuliginosus (Will.). Mem.
Proc. Manch. Lit. Phil. Soc. vol. xlvi. pt. 3.
—— (03) A biseriate Halonial branch of Lepidophloios fuliginosus. Trans.
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63.
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—— (07) The Parichnos in Lepidodendraceae. Mem. Proc. Manch. Lit.
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Page 664
White, D. (93) A new Taeniopteroid Fern and its allies. Bull. Geol. Soc.
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xlviii. pt. iii.
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Williamson, W. C. (72) On the organization of the fossil plants of the Coal-
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America, vol. iv. p. 119.
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329.
—— (99) Fossil flora of the Lower Coal-Measures of Missouri. U. S. Geol.
Surv. Mon. xxxvii.
—— (02) Description of a fossil alga from the Chemung of New York. Rep.
New York State Palaeontologist, 1901.
—— (04) The seeds of Aneimites. Smithsonian Miscell. Coll. vol. xlvii. pt.
iii. p. 322.
—— (05) See Smith, G. O. and D. White.
—— (052) Fossil plants of the group Cycadofilices. Smiths. Misc. Coll. vol.
xlviii. pt. iii.
—— (07) Permo-Carboniferous changes in South America. Journ. Geol.
vol. xv. p. 615.
—— (072) A remarkable fossil tree trunk from the Middle Devonic of New
York. New York State Mus. Bull. 107. Albany.
—— (08) Fossil flora of the Coal-Measures of Brazil. Rio de Janeiro.
White, I. C. (80) See Fontaine, W. M. and I. C. White.
Wickes, W. H. (00) A new Rhaetic section at Bristol. Proc. Geol. Assoc.
vol. xvi. p. 421.
Wigglesworth, Grace. (02) Notes on the rhizome of Matonia pectinata.
New Phyt. vol. i. p. 157.
Wild, G. and J. Lomax. (00) A new Cardiocarpon-bearing strobilus.
Annals Bot. vol. xiv. p. 160.
Williamson, W. C. (72) On the organization of the fossil plants of the Coal-
Measures. III. Lycopodiaceae. Phil. Trans. R. Soc. vol. clxii. p. 283.
—— (76) Ibid. pt. vii. Phil. Trans. R. Soc. vol. clxvi. p. 1.
Page 665
—— (77) Ibid. pt. viii. Phil. Trans. R. Soc. vol. clxvii. p. 213.
—— (83) Presidential address. Brit. Assoc.
—— (87) Note on Lepidodendron Harcourtii and L. fuliginosum. Proc. R.
Soc. vol. xlii. p. 6.
—— (92) Sigillaria and Stigmaria. Nat. Science, p. 214.
—— (93) On the organization &c. pt. xix. Phil. Trans. R. Soc. vol. clxxxiv.
p. 1.
—— (932) General morphological and histological index to the author’s
collective memoirs on the fossil plants of the Coal-Measures, pt. ii.
Mem. Proc. Manch. Lit. Phil. Soc. [7] vol. vii.
—— (95) On the light thrown upon the question of growth and
development of the Carboniferous arborescent Lepidodendra by a
study of the details of their organisation. Ibid. vol. ix. p. 31.
—— (96) Reminiscences of a Yorkshire Naturalist. (Edited by Mrs
Crawford Williamson.) London.
Woodward, A. Smith. (05) See Seward, A. C. and A. Smith Woodward.
Worsdell, W. C. (95) On transfusion-tissue; its origin and function in the
leaves of Gymnospermous plants. Trans. Linn. Soc. vol. v. p. 301.
Wünsch, E. A. (67) Discovery of erect stems of fossil trees in trappean ash
in Arran. Trans. Geol. Soc. Glasgow, vol. ii. p. 97.
Yabe, H. (05) Mesozoic plants from Korea. Journ. Colt. Sci. Imp. Univ.
Japan, vol. xx.
Yapp, R. H. (02) Two Malayan ‘Myrmecophilous’ ferns, Polypodium
(Lecanopteris) carnosum (Blume), and P. sinuosum. Annals Bot. vol.
xvi. p. 185.
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—— (83) Presidential address. Brit. Assoc.
—— (87) Note on Lepidodendron Harcourtii and L. fuliginosum. Proc. R.
Soc. vol. xlii. p. 6.
—— (92) Sigillaria and Stigmaria. Nat. Science, p. 214.
—— (93) On the organization &c. pt. xix. Phil. Trans. R. Soc. vol. clxxxiv.
p. 1.
—— (932) General morphological and histological index to the author’s
collective memoirs on the fossil plants of the Coal-Measures, pt. ii.
Mem. Proc. Manch. Lit. Phil. Soc. [7] vol. vii.
—— (95) On the light thrown upon the question of growth and
development of the Carboniferous arborescent Lepidodendra by a
study of the details of their organisation. Ibid. vol. ix. p. 31.
—— (96) Reminiscences of a Yorkshire Naturalist. (Edited by Mrs
Crawford Williamson.) London.
Woodward, A. Smith. (05) See Seward, A. C. and A. Smith Woodward.
Worsdell, W. C. (95) On transfusion-tissue; its origin and function in the
leaves of Gymnospermous plants. Trans. Linn. Soc. vol. v. p. 301.
Wünsch, E. A. (67) Discovery of erect stems of fossil trees in trappean ash
in Arran. Trans. Geol. Soc. Glasgow, vol. ii. p. 97.
Yabe, H. (05) Mesozoic plants from Korea. Journ. Colt. Sci. Imp. Univ.
Japan, vol. xx.
Yapp, R. H. (02) Two Malayan ‘Myrmecophilous’ ferns, Polypodium
(Lecanopteris) carnosum (Blume), and P. sinuosum. Annals Bot. vol.
xvi. p. 185.
—— (08) Sketches of vegetation at home and abroad. IV. Wicken Fen. New
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Yokoyama, M. (89) Jurassic plants from Kaga, Hida, and Echizen. Journ.
Coll. Sci. Imp. Univ. Japan, vol. iii.
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Page 666
Zalessky, M. (04) Végétaux fossiles du Terrain Carbonifère du Bassin du
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tome xxxii. p. 21.
—— (86) Présentation d’une brochure de M. Kidston sur les Ulodendron et
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—— (89) Sur les variations de formes du Sigillaria Brardi, Brongn. Ibid.
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—— (90) Bassin Houiller et Permien d’Autun et d’Épinac. Études des
Gîtes Min. France.
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do Sul. Bull. Soc. Géol. France [3], tome xxiii. p. 601.
—— (97) Observations sur quelques fougères des Dépôts houillers d’Asie
Mineure. Bull. Soc. Bot. France [3], tome xliv. p. 195.
—— (972) The reference of the genus Vertebraria. (Translation from the
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—— (07) Sur la présence de Mixoneura neuropteroides, Göpp. avec
Neuropteris Scheuchzeri, Hoffmann, et N. rarinervis, Bunbury &c.
Bull. Com. Géol. St Pétersbourg, tome xxvi.
—— (08) Végétaux fossiles du Terrain Carbonifère du bassin du Donetz. II.
Étude sur la structure anatomique d’un Lepidostrobus. Mém. Com.
Géol., Livr. xlvi.
Zeiller, R. (79) Note sur quelques fossiles du terrain permien de la Corrèze.
Bull. Soc. Géol. France, tome viii. p. 196.
—— (792) Note sur le genre Mariopteris. Bull. Soc. Géol. France [3], tome
vii. p. 92.
—— (83) Fructifications de Fougères houillères. Ann. Sci. nat. [6], vol. xvi.
—— (84) Cônes de fructification des Sigillaires. Ibid. vol. xix. p. 256.
—— (85) Sur les affinités du genre Laccopteris. Bull. Soc. Bot. France,
tome xxxii. p. 21.
—— (86) Présentation d’une brochure de M. Kidston sur les Ulodendron et
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Géol. France [3], tome xiv. p. 168.
—— (89) Sur les variations de formes du Sigillaria Brardi, Brongn. Ibid.
[3], tome xvii. p. 603.
—— (90) Bassin Houiller et Permien d’Autun et d’Épinac. Études des
Gîtes Min. France.
—— (94) Notes sur la flore des Couches Permiennes de Trienbach
(Alsace). Bull. Soc. Geol. France [3], tome xxii. p. 163.
—— (95) Note sur la flore fossile des Gisements houillers de Rio Grande
do Sul. Bull. Soc. Géol. France [3], tome xxiii. p. 601.
—— (97) Observations sur quelques fougères des Dépôts houillers d’Asie
Mineure. Bull. Soc. Bot. France [3], tome xliv. p. 195.
—— (972) The reference of the genus Vertebraria. (Translation from the
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—— (02) Observations sur quelques plantes fossiles des Lower
Gondwanas. Mem. Geol. Surv. India [New Series], vol. ii.
—— (03) Flore fossile des Gîtes de Charbon du Tonkin. Études des Gîtes
Min. France. Paris.
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xv.
—— (05) Une nouvelle classe de Gymnospermes: les Ptéridospermées.
Rev. Gén. Sci. p. 718.
—— (06) Bassin houiller et Permien de Blanzy et du Creusot (Fasc. ii).
Études Gîtes Min. France.
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cxlviii. p. 890.
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Page 668
Zenker, J. C. (37) Scolecopteris elegans Zenk. Ein neues fossiles
Farrngewächs mit Fructificationen. Linnaea, vol. xi. p. 509.
Farrngewächs mit Fructificationen. Linnaea, vol. xi. p. 509.
Page 669
Page 670
INDEX
The Index includes the names of Authors and plants mentioned in this
volume. No references are, however, given to the following Authors, whose
names occur too frequently to render special reference of use to the reader:
A. Brongniart, R. Kidston, A. G. Nathorst, H. Potonié, B. Renault, D. H.
Scott, H. Graf zu Solms-Laubach, D. Stur, W. C. Williamson, K. Zeiller.
Abies pectinata, 217
Acrostichites Goeppertianus, 340, 341
A. linnaeaefolius, 340
A. rhombifolius, 340
A. tenuifolius, 332
A. Williamsonis, 339
Acrostichum, 499, 500
A. aureum, 309, 379
A. (Lomariopsis) sorbifolium, 301
Adiantites, 376, 560
A. antiquus, 376, 377
A. lindsayoides, 376, 377
A. Sewardi, 377
Adiantum pedatum, 300
A. apalophyllum, 380
Agathis, 131, 195
A. australis, 95
The Index includes the names of Authors and plants mentioned in this
volume. No references are, however, given to the following Authors, whose
names occur too frequently to render special reference of use to the reader:
A. Brongniart, R. Kidston, A. G. Nathorst, H. Potonié, B. Renault, D. H.
Scott, H. Graf zu Solms-Laubach, D. Stur, W. C. Williamson, K. Zeiller.
Abies pectinata, 217
Acrostichites Goeppertianus, 340, 341
A. linnaeaefolius, 340
A. rhombifolius, 340
A. tenuifolius, 332
A. Williamsonis, 339
Acrostichum, 499, 500
A. aureum, 309, 379
A. (Lomariopsis) sorbifolium, 301
Adiantites, 376, 560
A. antiquus, 376, 377
A. lindsayoides, 376, 377
A. Sewardi, 377
Adiantum pedatum, 300
A. apalophyllum, 380
Agathis, 131, 195
A. australis, 95
Page 671
Alethopteris, 485, 516, 557, 572–576
A. Grandini, 574
A. lonchitica, 399, 553, 574, 575
A. Roesserti, 346
A. Serlii, 575, 576
Alloiopteris, 470, 579
A. Essinghii, 535
Alsophila, 295
A. excelsa, 294
A. tahitiensis, 309
Alsophilina, 372
Amalitzky, W., 498, 513
Anachoropteris Decaisnii, 462
Anachoropteroides, 455
Andrae, K. J., 390
Androstrobus, 88
Aneimia, 287, 288, 346, 350
A. flexuosa, 289
A. phyllitidis, 289
A. rotundifolia, 288, 307
Aneimites, 346
Angiopteridium, 485
A. californicum, 409
Angiopteris, 172, 317, 417, 425, 455, 527
A. evecta, 283, 317–319
A. Richthofeni, 409
A. Grandini, 574
A. lonchitica, 399, 553, 574, 575
A. Roesserti, 346
A. Serlii, 575, 576
Alloiopteris, 470, 579
A. Essinghii, 535
Alsophila, 295
A. excelsa, 294
A. tahitiensis, 309
Alsophilina, 372
Amalitzky, W., 498, 513
Anachoropteris Decaisnii, 462
Anachoropteroides, 455
Andrae, K. J., 390
Androstrobus, 88
Aneimia, 287, 288, 346, 350
A. flexuosa, 289
A. phyllitidis, 289
A. rotundifolia, 288, 307
Aneimites, 346
Angiopteridium, 485
A. californicum, 409
Angiopteris, 172, 317, 417, 425, 455, 527
A. evecta, 283, 317–319
A. Richthofeni, 409
Page 672
Ankyropteris, 365, 450–462, 465
A. bibractensis, 453–456, 471
A. corrugata, 436, 453, 455–462, 471
A. scandens, 450–452, 456, 461, 462, 471
Anomopteris Mougeotii, 329
A. Schlectendalii, 329
Anomozamites, 489
Antrophyum, 499
Aphlebia 525–529, 533–536, 555
A. crispa, 526, 528
A. Germari, 526
Aphyllum cristatum, 127
Araucaria, 25
A. Balansae, 36
A. excelsa, 36
A. imbricata, 93, 211
Araucarieae, 44, 275
Araucarites Cordai, 187
A. gracilis, 84
Arber, E. A. N., 178, 395, 420, 433, 497, 500, 507, 508, 512, 513
Arber, E. A. N. and H. H. Thomas, 214, 222
Arberia, 516
A. minasica, 516
Arberia sp., 517
Archaeopterideae, 565
Archaeopteris, 15, 526, 560–565
A. bibractensis, 453–456, 471
A. corrugata, 436, 453, 455–462, 471
A. scandens, 450–452, 456, 461, 462, 471
Anomopteris Mougeotii, 329
A. Schlectendalii, 329
Anomozamites, 489
Antrophyum, 499
Aphlebia 525–529, 533–536, 555
A. crispa, 526, 528
A. Germari, 526
Aphyllum cristatum, 127
Araucaria, 25
A. Balansae, 36
A. excelsa, 36
A. imbricata, 93, 211
Araucarieae, 44, 275
Araucarites Cordai, 187
A. gracilis, 84
Arber, E. A. N., 178, 395, 420, 433, 497, 500, 507, 508, 512, 513
Arber, E. A. N. and H. H. Thomas, 214, 222
Arberia, 516
A. minasica, 516
Arberia sp., 517
Archaeopterideae, 565
Archaeopteris, 15, 526, 560–565
Page 673
A. archetypus, 563–565
A. Dawsoni, 564
A. fimbriata, 563–565
A. fissilis, 563, 564
A. gaspiensis, 563
A. hibernica, 561–565
A. Jacksoni, 563
A. Roemeriana, 563
A. Tschermaki, 564
Archaeosigillaria, 78, 267, 268
A. primaeva, 201, 268
Archangiopteris, 318, 319
Arctopodium insigne, 456
Artis, F. T., 127, 196, 229, 231, 422
Aspidiaria, 124, 127, 128
Aspidites caudatus, 404
Asplenites, 580
A. macrocarpus, 346
A. ottonis, 346
Asplenium Johnstrupi, 369
A. multilineatum, 301
A. nebbense, 344
A. nidus, 485
A. resectum, 300
A. whitbiense, 344
Asterochlaena duplex, 448
A. Dawsoni, 564
A. fimbriata, 563–565
A. fissilis, 563, 564
A. gaspiensis, 563
A. hibernica, 561–565
A. Jacksoni, 563
A. Roemeriana, 563
A. Tschermaki, 564
Archaeosigillaria, 78, 267, 268
A. primaeva, 201, 268
Archangiopteris, 318, 319
Arctopodium insigne, 456
Artis, F. T., 127, 196, 229, 231, 422
Aspidiaria, 124, 127, 128
Aspidites caudatus, 404
Asplenites, 580
A. macrocarpus, 346
A. ottonis, 346
Asplenium Johnstrupi, 369
A. multilineatum, 301
A. nebbense, 344
A. nidus, 485
A. resectum, 300
A. whitbiense, 344
Asterochlaena duplex, 448
Page 674
A. laxa, 462, 471, 472
A. ramosa, 471
Asterotheca, 398, 409, 426, 576
A. Sternbergii, 398, 400
Aulacopteris, 567
Azolla, 192, 274, 475
Baiera, 307, 390
Baily, W. H., 469, 537, 560, 562
Baker, J. G., 33, 307
Balfour, J. H., 191
Barrois, C., 103
Bartholin, C. T., 392
Bates, H. W., 309
Bennettitales, 396
Bennie, J., 7
Bennie, J. and R. Kidston, 85
Benson, Margaret, 277, 532
Bensonites fusiformis, 469
Bergeria, 124, 126, 127, 174, 181
Bernouillia, 409, 410, 541
Berridge, E. M., 194
Berry, E. W., 543
Bertrand, C. E., 163, 213, 214, 222, 275, 277
Bertrand, C. E. and F. Cornaille, 316
Bertrand, P., 432, 434, 435, 443, 447, 449–452, 462, 467, 468
A. ramosa, 471
Asterotheca, 398, 409, 426, 576
A. Sternbergii, 398, 400
Aulacopteris, 567
Azolla, 192, 274, 475
Baiera, 307, 390
Baily, W. H., 469, 537, 560, 562
Baker, J. G., 33, 307
Balfour, J. H., 191
Barrois, C., 103
Bartholin, C. T., 392
Bates, H. W., 309
Bennettitales, 396
Bennie, J., 7
Bennie, J. and R. Kidston, 85
Benson, Margaret, 277, 532
Bensonites fusiformis, 469
Bergeria, 124, 126, 127, 174, 181
Bernouillia, 409, 410, 541
Berridge, E. M., 194
Berry, E. W., 543
Bertrand, C. E., 163, 213, 214, 222, 275, 277
Bertrand, C. E. and F. Cornaille, 316
Bertrand, P., 432, 434, 435, 443, 447, 449–452, 462, 467, 468
Page 675
Binney, E. W., 103, 110, 137, 153, 164, 171, 188, 232, 238, 462, 465
Bischof, — 69
Blanckenhorn, M., 72, 522, 523
Blechnoxylon talbragarense, 509–511
Bommer, C., 40, 353, 361
Boodle, L. A., 20, 21, 24, 304, 311, 468
Bothrodendreae, 248–266
Bothrodendron, 75, 128, 130–133, 137, 188, 209, 234, 240, 248–268,
276
B. kiltorkense, 252, 255, 257–259
B. Leslei, 258
B. minutifolium, 251–256, 262
B. mundum, 256, 262, 263
B. punctatum, 135, 248, 250, 252, 254, 260
B. tenerrimum, 264
Bothrostrobus, 192, 262–264, 278
Botrychioxylon, 459
Botrychium, 169, 427, 438, 459, 510
B. Lunaria, 322
B. virginianum, 322
Botryoptereae, 434–443
Botryopterideae, 325, 365, 375, 427, 432–472
Botryopteris, 436–443
Botryopteris antiqua, 436, 442, 443, 470, 471
B. cylindrica, 436, 438
B. forensis, 437, 438, 442–445, 463, 470
Bischof, — 69
Blanckenhorn, M., 72, 522, 523
Blechnoxylon talbragarense, 509–511
Bommer, C., 40, 353, 361
Boodle, L. A., 20, 21, 24, 304, 311, 468
Bothrodendreae, 248–266
Bothrodendron, 75, 128, 130–133, 137, 188, 209, 234, 240, 248–268,
276
B. kiltorkense, 252, 255, 257–259
B. Leslei, 258
B. minutifolium, 251–256, 262
B. mundum, 256, 262, 263
B. punctatum, 135, 248, 250, 252, 254, 260
B. tenerrimum, 264
Bothrostrobus, 192, 262–264, 278
Botrychioxylon, 459
Botrychium, 169, 427, 438, 459, 510
B. Lunaria, 322
B. virginianum, 322
Botryoptereae, 434–443
Botryopterideae, 325, 365, 375, 427, 432–472
Botryopteris, 436–443
Botryopteris antiqua, 436, 442, 443, 470, 471
B. cylindrica, 436, 438
B. forensis, 437, 438, 442–445, 463, 470
Page 676
B. hirsuta, 436, 438
B. ramosa, 436, 438, 440, 441, 470
Boulay, N., 251
Bowenia, 549
B. spectabilis, 438
Bower, F. O., 13, 14, 17, 44, 46, 53, 78, 191, 264, 268, 282, 284, 296,
298, 300, 307, 325
Bowman, J. E., 232
Brabenec, — 476
Brainea, 299
Brittsia, 464
B. problematica, 464
Brodie, P. B., 82
Brongniart, A. See note, page 609
Brown, Richard, 232, 233, 237, 239
Brown, Robert, 160, 190
Browne, Lady Isabel, 267, 269
Bruchmann, H., 64
Bunbury, Sir Charles, 348, 352, 481, 570, 572
Butterworth, J., 171, 413
Calamites, 6, 11, 73, 207, 208
C. radiatus, 11, 265, 256
Calamodendron, 73
Calamostachys, 9
Callipteridium, 560
C. gigas, 557
B. ramosa, 436, 438, 440, 441, 470
Boulay, N., 251
Bowenia, 549
B. spectabilis, 438
Bower, F. O., 13, 14, 17, 44, 46, 53, 78, 191, 264, 268, 282, 284, 296,
298, 300, 307, 325
Bowman, J. E., 232
Brabenec, — 476
Brainea, 299
Brittsia, 464
B. problematica, 464
Brodie, P. B., 82
Brongniart, A. See note, page 609
Brown, Richard, 232, 233, 237, 239
Brown, Robert, 160, 190
Browne, Lady Isabel, 267, 269
Bruchmann, H., 64
Bunbury, Sir Charles, 348, 352, 481, 570, 572
Butterworth, J., 171, 413
Calamites, 6, 11, 73, 207, 208
C. radiatus, 11, 265, 256
Calamodendron, 73
Calamostachys, 9
Callipteridium, 560
C. gigas, 557
Page 677
C. pteridium, 560
Callipteris, 556–560
C. Bergeroni, 558
C. conferta, 558–560
C. conferta var. polymorpha, 559
C. flabellifera, 568
C. lyratifolia, 557, 558
Calymmatotheca, 407, 531, 532
C. affinis, 532
C. Stangeri, 531
Campbell, D. H., 68, 192, 308
Camptopteridinae, 385
Camptopteris, 389, 390
C. exilis, 381
C. lunzensis, 385
C. Phillipsii, 383
C. spiralis, 382, 389, 390
Cancellatae, 203
Canna, 517
Cannophyllites, 517
Cardiocarpon, 271
C. anomalum, 271
Cardiopteris, 519, 523–525
C. frondosa, 523–526
C. Hochstetterii var. franconica, 524
C. Zuberi, 540
Callipteris, 556–560
C. Bergeroni, 558
C. conferta, 558–560
C. conferta var. polymorpha, 559
C. flabellifera, 568
C. lyratifolia, 557, 558
Calymmatotheca, 407, 531, 532
C. affinis, 532
C. Stangeri, 531
Campbell, D. H., 68, 192, 308
Camptopteridinae, 385
Camptopteris, 389, 390
C. exilis, 381
C. lunzensis, 385
C. Phillipsii, 383
C. spiralis, 382, 389, 390
Cancellatae, 203
Canna, 517
Cannophyllites, 517
Cardiocarpon, 271
C. anomalum, 271
Cardiopteris, 519, 523–525
C. frondosa, 523–526
C. Hochstetterii var. franconica, 524
C. Zuberi, 540
Page 678
Carica sp., 202, 203
Carolopteris, 360
Carruthers, W., 27, 130, 137, 163, 171, 175–181, 271, 339, 374, 491,
514, 562, 565
Cash, W. and J. Lomax, 154
Castilloa, 131
Caulopteris, 372, 413, 421, 422
C. anglica, 421
C. gigantea, 424
C. peltigera, 419–422
C. Saportae, 421
C. tessellata, 90
Cephalotheca, 29, 537
C. mirabilis, 536, 537
Ceratopteris, 303
C. thalictroides, 297
Ceratozamia, 565
Cheirolepis, 84
Cheiropteris palmatopedata, 300
Cheirostrobeae, 12
Cheirostrobus, 7–12, 14, 15, 21, 24
C. pettycurensis, 8
Chiropteris, 431
C. spatulata, 431
C. Williamsii, 431
C. Zeilleri, 430
Carolopteris, 360
Carruthers, W., 27, 130, 137, 163, 171, 175–181, 271, 339, 374, 491,
514, 562, 565
Cash, W. and J. Lomax, 154
Castilloa, 131
Caulopteris, 372, 413, 421, 422
C. anglica, 421
C. gigantea, 424
C. peltigera, 419–422
C. Saportae, 421
C. tessellata, 90
Cephalotheca, 29, 537
C. mirabilis, 536, 537
Ceratopteris, 303
C. thalictroides, 297
Ceratozamia, 565
Cheirolepis, 84
Cheiropteris palmatopedata, 300
Cheirostrobeae, 12
Cheirostrobus, 7–12, 14, 15, 21, 24
C. pettycurensis, 8
Chiropteris, 431
C. spatulata, 431
C. Williamsii, 431
C. Zeilleri, 430
Page 679
Chodat, R., 280, 281, 316
Chorionopteris gleichenoides, 476
Christ, H., 293
Christ, H. and K. Giesenhagen, 319
Chrysodium lanzaeanum, 350, 378
Cladophlebis, 343–346, 579, 580
C. Albertsii, 344
C. Brownii, 349
C. denticulata, 332, 335, 340–346
C. Dunkeri, 349
C. koraiensis, 349
C. lobifolia, 529
C. Roesserti, 343
C. virginiensis, 340
Clathraria, 203
C. Brardi, 198, 224
Clathropteris, 385–389
C. egyptiaca, 388, 389
C. meniscoides, 386, 387
C. platyphylla, 387
C. whitbyensis, 383
Clepsydropsis, 448–450
C. antiqua, 444, 446, 449
Coenopterideae, 365, 432–472, 526
Coniopteris, 367, 368, 409
C. arguta, 370, 371
Chorionopteris gleichenoides, 476
Christ, H., 293
Christ, H. and K. Giesenhagen, 319
Chrysodium lanzaeanum, 350, 378
Cladophlebis, 343–346, 579, 580
C. Albertsii, 344
C. Brownii, 349
C. denticulata, 332, 335, 340–346
C. Dunkeri, 349
C. koraiensis, 349
C. lobifolia, 529
C. Roesserti, 343
C. virginiensis, 340
Clathraria, 203
C. Brardi, 198, 224
Clathropteris, 385–389
C. egyptiaca, 388, 389
C. meniscoides, 386, 387
C. platyphylla, 387
C. whitbyensis, 383
Clepsydropsis, 448–450
C. antiqua, 444, 446, 449
Coenopterideae, 365, 432–472, 526
Coniopteris, 367, 368, 409
C. arguta, 370, 371
Page 680
C. hymenophylloides, 366–370, 528
C. lunzensis, 367
C. Murrayana, 367
C. quinqueloba, 370
Corda, A. J., 68, 69, 105, 346, 347, 354, 373, 422, 443, 476
Corynepteris, 469, 470, 578
C. coralloides, 445
C. stellata, 469
Cotta, C. B., 412, 443
Coward, K. H., 221
Crematopteris, 523
Crépin, F., 27, 537, 563
Crossotheca, 396
Cryptomeria, 36
Ctenis Leckenbyi, 549
Ctenopteris, 548–550
C. cycadea, 548, 549
C. Sarrani, 541, 549
Ctenozamites, 548
Cyathea, 295, 313
C. dealbata, 344
C. Imrayana, 313
Cyathea sinuata, 295
C. spinulosa, 294
Cyatheaceae, 294–296, 365–375, 403
Cyatheites, 366
C. lunzensis, 367
C. Murrayana, 367
C. quinqueloba, 370
Corda, A. J., 68, 69, 105, 346, 347, 354, 373, 422, 443, 476
Corynepteris, 469, 470, 578
C. coralloides, 445
C. stellata, 469
Cotta, C. B., 412, 443
Coward, K. H., 221
Crematopteris, 523
Crépin, F., 27, 537, 563
Crossotheca, 396
Cryptomeria, 36
Ctenis Leckenbyi, 549
Ctenopteris, 548–550
C. cycadea, 548, 549
C. Sarrani, 541, 549
Ctenozamites, 548
Cyathea, 295, 313
C. dealbata, 344
C. Imrayana, 313
Cyathea sinuata, 295
C. spinulosa, 294
Cyatheaceae, 294–296, 365–375, 403
Cyatheites, 366
Page 681
Cyathocarpus dentatus, 404
Cyathotrachus altus, 398
Cycadophyta, 484
Cycadopteris, 544, 546
Cycas, 133
C. Micholitzii, 307
Cyclopteris, 560, 561, 566, 571–572
C. angustifolia, 512
C. hibernica, 560
C. Roemeriana, 563
Cyclostigma, 251
C. australe, 259
C. densifolium, 257
C. Griffithsi, 251, 255
C. hercynium, 257
C. kiltorkense, 251, 255, 257
C. minutum, 251, 255
Cyparissidium, 39
Cyperus papyrus, 230
Czekanowskia, 67
Dacrydium, 36
D. cupressinum, 75
D. Kirkii, 75
Dactylotheca, 396, 404–406, 527, 565, 576
D. dentata, 404
Cyathotrachus altus, 398
Cycadophyta, 484
Cycadopteris, 544, 546
Cycas, 133
C. Micholitzii, 307
Cyclopteris, 560, 561, 566, 571–572
C. angustifolia, 512
C. hibernica, 560
C. Roemeriana, 563
Cyclostigma, 251
C. australe, 259
C. densifolium, 257
C. Griffithsi, 251, 255
C. hercynium, 257
C. kiltorkense, 251, 255, 257
C. minutum, 251, 255
Cyparissidium, 39
Cyperus papyrus, 230
Czekanowskia, 67
Dacrydium, 36
D. cupressinum, 75
D. Kirkii, 75
Dactylotheca, 396, 404–406, 527, 565, 576
D. dentata, 404
Page 682
D. plumosa, 399, 400, 404–406
Danaea, 321, 398
D. microphylla, 410
D. trichomanoides, 300
Danaeites, 398, 485
D. Heeri, 410
D. sarepontanus, 398, 400
Danaeopsis, 407
D. Hughesi, 409
D. marantacea, 408
D. Storrsii, 345
Darwin, C., 103, 301, 514
Davallia, 28, 293, 296, 366
D. aculeata, 299, 300, 355, 533
D. concinna, 294
Dawes, J. S., 130, 137, 153
Dawson, Sir J. W., 26–29, 177, 257, 346, 476, 563
Debey, M. H. and C. von Ettingshausen, 355, 360
Dechenia Roemeriana, 257
Dennstaedtiinae, 296
Derbyella, 516
D. aurita, 517
Dichopteris, 550–552
D. lanceolata, 551
D. visianica, 550, 551
Dicksonia, 293, 366, 374
Danaea, 321, 398
D. microphylla, 410
D. trichomanoides, 300
Danaeites, 398, 485
D. Heeri, 410
D. sarepontanus, 398, 400
Danaeopsis, 407
D. Hughesi, 409
D. marantacea, 408
D. Storrsii, 345
Darwin, C., 103, 301, 514
Davallia, 28, 293, 296, 366
D. aculeata, 299, 300, 355, 533
D. concinna, 294
Dawes, J. S., 130, 137, 153
Dawson, Sir J. W., 26–29, 177, 257, 346, 476, 563
Debey, M. H. and C. von Ettingshausen, 355, 360
Dechenia Roemeriana, 257
Dennstaedtiinae, 296
Derbyella, 516
D. aurita, 517
Dichopteris, 550–552
D. lanceolata, 551
D. visianica, 550, 551
Dicksonia, 293, 366, 374
Page 683
D. antarctica, 424
D. Bertervana, 295
Dicksonia coniifolia, 294
D. culcita, 294
D. Johnstrupi, 369, 370
D. lobifolia, 529
Dicksonites Pluckeneti, 366
Dictophyllum, 380–385
D. acutilobum, 381
D. exile, 381–383, 386
D. Fuchsi, 385
D. Nathorsti, 383, 385, 387
D. Nilssoni, 382
D. rugosum, 380, 383–385
Dictyopteris, 571, 572
Dictyoxylon, 220
Didymochlaena, 574
Didymophyllum Schollini, 124
Didymosorus comptonifolius, 355
Diplolabis, 433, 434, 446–449, 465
D. esnostensis, 447, 448
D. forensis, 444–446
Diplotmema, 351, 530, 533–537
D. furcatum, 529, 536
D. Zeilleri, 535, 536
Dipteridinae, 298, 380–394
D. Bertervana, 295
Dicksonia coniifolia, 294
D. culcita, 294
D. Johnstrupi, 369, 370
D. lobifolia, 529
Dicksonites Pluckeneti, 366
Dictophyllum, 380–385
D. acutilobum, 381
D. exile, 381–383, 386
D. Fuchsi, 385
D. Nathorsti, 383, 385, 387
D. Nilssoni, 382
D. rugosum, 380, 383–385
Dictyopteris, 571, 572
Dictyoxylon, 220
Didymochlaena, 574
Didymophyllum Schollini, 124
Didymosorus comptonifolius, 355
Diplolabis, 433, 434, 446–449, 465
D. esnostensis, 447, 448
D. forensis, 444–446
Diplotmema, 351, 530, 533–537
D. furcatum, 529, 536
D. Zeilleri, 535, 536
Dipteridinae, 298, 380–394
Page 684
Dipteris, 308, 312, 381, 390, 393, 394, 533
D. bifurcata, 298
D. conjugata, 297, 298, 384
D. Lobbiana, 298
D. quinquefurcata, 297
D. Wallichii, 297, 298
Discopteris, 402, 403
D. cristata, 402, 403
D. karwinensis, 402, 403
D. Rallii, 340, 500
D. Schumanni, 402
Drymoglossum carnosum, 304
Drynaria fascia, 411
Dunker, W., 390
Eichwald, E. d’, 326, 329
Endogenites, 412
Engler, A., 282
Equisetales, 10, 15
Etapteris, 435, 465
E. Scotti, 444, 462, 463
Etheridge, R., 505, 510
Ettingshausen, C. von, 25, 364, 376, 537, 542
Eufilicineae, 283–316
Euphorbia, 196, 231
Euphorbites vulgaris, 196, 198
D. bifurcata, 298
D. conjugata, 297, 298, 384
D. Lobbiana, 298
D. quinquefurcata, 297
D. Wallichii, 297, 298
Discopteris, 402, 403
D. cristata, 402, 403
D. karwinensis, 402, 403
D. Rallii, 340, 500
D. Schumanni, 402
Drymoglossum carnosum, 304
Drynaria fascia, 411
Dunker, W., 390
Eichwald, E. d’, 326, 329
Endogenites, 412
Engler, A., 282
Equisetales, 10, 15
Etapteris, 435, 465
E. Scotti, 444, 462, 463
Etheridge, R., 505, 510
Ettingshausen, C. von, 25, 364, 376, 537, 542
Eufilicineae, 283–316
Euphorbia, 196, 231
Euphorbites vulgaris, 196, 198
Page 685
Eu-Sigillariae, 203
Eusphenopteris tenella, 407
Farmer, J. B. and T. G. Hill, 318, 418
Favularia, 198, 203
Fée, A. L. A., 301
Feistmantel, C., 84, 126, 136, 137, 346, 372, 409, 430, 489, 513, 540,
541
Feistmantel, O., 430
Felix, J., 438
Ferns, fossil, 324–472
—— recent, 280–323
Ficoidites verrucosus, 231
Filicales, 280–472
Filicites arborescens, 577
F. cycadea, 548
F. dubius, 181, 496
F. lineatus, 537
F. lonchiticus, 574
F. meniscoides, 386
F. Miltoni, 399
F. Nilssoniana, 482
F. plumosus, 404
F. pteridius, 560
Fitting, H., 72, 73
Flemingites, 181
F. Pedroanus, 177
Eusphenopteris tenella, 407
Farmer, J. B. and T. G. Hill, 318, 418
Favularia, 198, 203
Fée, A. L. A., 301
Feistmantel, C., 84, 126, 136, 137, 346, 372, 409, 430, 489, 513, 540,
541
Feistmantel, O., 430
Felix, J., 438
Ferns, fossil, 324–472
—— recent, 280–323
Ficoidites verrucosus, 231
Filicales, 280–472
Filicites arborescens, 577
F. cycadea, 548
F. dubius, 181, 496
F. lineatus, 537
F. lonchiticus, 574
F. meniscoides, 386
F. Miltoni, 399
F. Nilssoniana, 482
F. plumosus, 404
F. pteridius, 560
Fitting, H., 72, 73
Flemingites, 181
F. Pedroanus, 177
Page 686
Fliche, P., 73, 90, 91
Flicheia esnostensis, 448
Fontaine, W. M., 342, 343, 345, 352, 362, 363, 368, 378, 543
Fontaine, W. M. and I. C. White, 424, 487, 570
Frič, A. and E. Bayer, 375, 474
Fritel, P. H., 476
Fritsch, K. von, 524
Forbes, E., 380, 560
Fucoides, 525
Gangamopteris, 512–517
G. cyclopteroides, 514–516
G. kashmirensis, 516, 517
Gangamopteris flora, 181, 513
Gardiner, Stanley, 43
Gardner, J. S., 82
Gardner, J. S. and C. von Ettingshausen, 339, 350, 380, 394
Geinitz, H. B., 26, 79, 130, 174, 233, 402, 491, 540, 561
Germar, E. F., 69, 201, 265
Geyler, H. T., 378
Gilkinet, A., 28, 537
Ginkgo, 307
G. digitata, 376
Gleichenia, 83, 311, 312, 351, 446, 526, 533
G. circinata, 289
G. Cunninghami, 300
Flicheia esnostensis, 448
Fontaine, W. M., 342, 343, 345, 352, 362, 363, 368, 378, 543
Fontaine, W. M. and I. C. White, 424, 487, 570
Frič, A. and E. Bayer, 375, 474
Fritel, P. H., 476
Fritsch, K. von, 524
Forbes, E., 380, 560
Fucoides, 525
Gangamopteris, 512–517
G. cyclopteroides, 514–516
G. kashmirensis, 516, 517
Gangamopteris flora, 181, 513
Gardiner, Stanley, 43
Gardner, J. S., 82
Gardner, J. S. and C. von Ettingshausen, 339, 350, 380, 394
Geinitz, H. B., 26, 79, 130, 174, 233, 402, 491, 540, 561
Germar, E. F., 69, 201, 265
Geyler, H. T., 378
Gilkinet, A., 28, 537
Ginkgo, 307
G. digitata, 376
Gleichenia, 83, 311, 312, 351, 446, 526, 533
G. circinata, 289
G. Cunninghami, 300
Page 687
G. dicarpa, 290, 310, 351, 354
G. dichotoma, 290, 291
G. dubia, 344
G. hantonensis, 355
G. linearis, 291
G. lineata, 540
G. moniliformis, 291
Gleicheniaceae, 288–291, 351–355
Gleichenites, 351
G. elegans, 353
G. gracilis, 353
G. hantonensis, 356
G. longipennis, 354
G. microphyllus, 353
G. neuropteroides, 351
G. Nordenskioldii, 354
G. Rostafinskii, 290, 353
G. Zippei, 354, 355
Glenopteris, 538
Glossopteris, 309, 496–512
G. angustifolia, 507, 508, 509
G. angustifolia var. taeniopteroides, 508
G. Browniana, 496–507
G. conspicua, 512
Glossopteris flora, 181, 513, 514
G. indica, 505–508, 512
G. dichotoma, 290, 291
G. dubia, 344
G. hantonensis, 355
G. linearis, 291
G. lineata, 540
G. moniliformis, 291
Gleicheniaceae, 288–291, 351–355
Gleichenites, 351
G. elegans, 353
G. gracilis, 353
G. hantonensis, 356
G. longipennis, 354
G. microphyllus, 353
G. neuropteroides, 351
G. Nordenskioldii, 354
G. Rostafinskii, 290, 353
G. Zippei, 354, 355
Glenopteris, 538
Glossopteris, 309, 496–512
G. angustifolia, 507, 508, 509
G. angustifolia var. taeniopteroides, 508
G. Browniana, 496–507
G. conspicua, 512
Glossopteris flora, 181, 513, 514
G. indica, 505–508, 512
Page 688
G. longifolia, 482
G. Phillipsi, 480
G. retifera, 511, 512
G. Tatei, 512
Goebel, K., 301, 526
Goeppert, H. R., 124, 228, 233, 235, 351, 366, 385, 398
Goldenberg, F., 76, 77, 79, 86, 87, 126, 198, 208, 217, 231
Gomphostrobus, 25, 26
Gonatosorus Nathorsti, 366
Goniopteris unita, 397
Gordon, W. T., 177, 447, 448, 471
Gradatae, 285, 298
Grammatopteris, 434–436, 443, 471
G. Rigolloti, 434
Grand’Eury, C., 137, 200, 204, 205, 226, 234–238, 352, 366, 398, 414,
426, 464, 532, 534, 555–557, 565, 567, 572, 575, 576
Gresley, W. S., 228
Grigoriew, N., 524
Gunn, Marcus, 361, 392
Gunnera, 528
G. manicata, 527
Gutbier, A. von, 525, 572
Gwynne-Vaughan, D. T., 113, 314, 327, 375, 461
Gymnogramme reniformis, 300
Haliserites Dechianus, 27
Halle, T. G., 76–80, 83, 87
G. Phillipsi, 480
G. retifera, 511, 512
G. Tatei, 512
Goebel, K., 301, 526
Goeppert, H. R., 124, 228, 233, 235, 351, 366, 385, 398
Goldenberg, F., 76, 77, 79, 86, 87, 126, 198, 208, 217, 231
Gomphostrobus, 25, 26
Gonatosorus Nathorsti, 366
Goniopteris unita, 397
Gordon, W. T., 177, 447, 448, 471
Gradatae, 285, 298
Grammatopteris, 434–436, 443, 471
G. Rigolloti, 434
Grand’Eury, C., 137, 200, 204, 205, 226, 234–238, 352, 366, 398, 414,
426, 464, 532, 534, 555–557, 565, 567, 572, 575, 576
Gresley, W. S., 228
Grigoriew, N., 524
Gunn, Marcus, 361, 392
Gunnera, 528
G. manicata, 527
Gutbier, A. von, 525, 572
Gwynne-Vaughan, D. T., 113, 314, 327, 375, 461
Gymnogramme reniformis, 300
Haliserites Dechianus, 27
Halle, T. G., 76–80, 83, 87
Page 689
Halonia, 128, 135–139, 148, 150, 153, 154
H. regularis, 141, 153
H. tortuosa, 136
Hapalopteris, 406
Harcourt, C. G. V. V., 160
Harvey, W. H., 303
Harvey-Gibson, R. J., 51, 54, 55
Haughton, S., 251, 255
Hausmannia, 390–394
H. dichotoma, 391, 392
H. Forchammeri, 392
H. Kohlmanni, 374, 392
H. Richteri, 393
H. Sewardi, 374, 393
Hawkshaw, J., 232, 238
Hawlea, 398, 400, 401, 576
H. Miltoni, 399, 400
H. pulcherrima, 399, 400
Hayden, H. H., 514
Heer, O., 11, 25, 84, 257, 351, 354, 355, 368, 369, 375, 407, 410, 411,
474
Hegelmaier, F., 43
Helminthostachys, 322, 434, 436, 438
Hemingway, W., 79, 253, 571, 574
Hemitelia capensis, 302, 304, 528
Hemitelites, 366
H. regularis, 141, 153
H. tortuosa, 136
Hapalopteris, 406
Harcourt, C. G. V. V., 160
Harvey, W. H., 303
Harvey-Gibson, R. J., 51, 54, 55
Haughton, S., 251, 255
Hausmannia, 390–394
H. dichotoma, 391, 392
H. Forchammeri, 392
H. Kohlmanni, 374, 392
H. Richteri, 393
H. Sewardi, 374, 393
Hawkshaw, J., 232, 238
Hawlea, 398, 400, 401, 576
H. Miltoni, 399, 400
H. pulcherrima, 399, 400
Hayden, H. H., 514
Heer, O., 11, 25, 84, 257, 351, 354, 355, 368, 369, 375, 407, 410, 411,
474
Hegelmaier, F., 43
Helminthostachys, 322, 434, 436, 438
Hemingway, W., 79, 253, 571, 574
Hemitelia capensis, 302, 304, 528
Hemitelites, 366
Page 690
Henry, A., 319
Hepaticae, 308
Heterangium, 77, 351, 532
Hexagonocarpon, 572
Hick, T., 157–159, 438
Hill, A. W., 42, 164, 286
Hill, T. G., 61, 65
Hofmeister, W., 56, 63
Hollick, A., 25, 474, 475
Hooker, Sir Joseph, 40, 130, 246, 309
Hooker, Sir J. and E. W. Binney, 185
Hooker, Sir William, 291
Hose, C., 291
Hostinella, 28
Hovelacque, M., 111
Hutton, W., 255
Hydropterideae, 280, 284, 473–483
Hymenophyllaceae, 294, 301, 363–365, 434, 465
Hymenophyllites, 363
H. patentissima, 364
H. Phillipsi, 367
H. quadridactylites, 365
Hymenophyllum dilatatum, 289
H. tunbridgense, 294, 300, 315
H. waldenburgense, 363
H. Weissi, 364
Hepaticae, 308
Heterangium, 77, 351, 532
Hexagonocarpon, 572
Hick, T., 157–159, 438
Hill, A. W., 42, 164, 286
Hill, T. G., 61, 65
Hofmeister, W., 56, 63
Hollick, A., 25, 474, 475
Hooker, Sir Joseph, 40, 130, 246, 309
Hooker, Sir J. and E. W. Binney, 185
Hooker, Sir William, 291
Hose, C., 291
Hostinella, 28
Hovelacque, M., 111
Hutton, W., 255
Hydropterideae, 280, 284, 473–483
Hymenophyllaceae, 294, 301, 363–365, 434, 465
Hymenophyllites, 363
H. patentissima, 364
H. Phillipsi, 367
H. quadridactylites, 365
Hymenophyllum dilatatum, 289
H. tunbridgense, 294, 300, 315
H. waldenburgense, 363
H. Weissi, 364
Page 691
H. Wilsoni, 294
Hymenopteris psilotoides, 378
Inversicatenales, 432
Isoetaceae, 33, 58–66
Isoetes, 30–33, 46, 58–68, 72, 88–91, 103, 175, 184, 191, 208, 217,
246, 269, 274, 277, 278
Isoetes Boryana, 60
I. Braunii, 68
I. Choffati, 66
I. echinospora, 58, 59
I. hystrix, 33, 60, 61, 65, 66
I. lacustris, 33, 58, 59, 61, 62, 66
I. Scheuzeri, 68
I. setacea, 68
Isoetites, 67, 68
I. Choffati, 67
I. crociformis, 67
Isoetopsis, 68
I. subaphylla, 68
Jack, R. L. and R. Etheridge, 509
Jahn, J. J., 28
Jamesonia, 304, 312
Jeffrey, E. C., 113, 310, 312, 315
Jordan, R., 461
Juncus, 58
Hymenopteris psilotoides, 378
Inversicatenales, 432
Isoetaceae, 33, 58–66
Isoetes, 30–33, 46, 58–68, 72, 88–91, 103, 175, 184, 191, 208, 217,
246, 269, 274, 277, 278
Isoetes Boryana, 60
I. Braunii, 68
I. Choffati, 66
I. echinospora, 58, 59
I. hystrix, 33, 60, 61, 65, 66
I. lacustris, 33, 58, 59, 61, 62, 66
I. Scheuzeri, 68
I. setacea, 68
Isoetites, 67, 68
I. Choffati, 67
I. crociformis, 67
Isoetopsis, 68
I. subaphylla, 68
Jack, R. L. and R. Etheridge, 509
Jahn, J. J., 28
Jamesonia, 304, 312
Jeffrey, E. C., 113, 310, 312, 315
Jordan, R., 461
Juncus, 58
Page 692
Karsten, G., 301
Kaulfussia, 321, 434
Kerr, T., 164
Kidston, B. See note, page 609
Kidston, B. and J. Bennie, 191
Kidston, B. and D. T. Gwynne-Vaughan, 267, 314, 326, 329, 334, 338,
346, 377, 461, 472
Kidstonia heracleensis, 325, 340
Klukia, 348
K. exilis, 347–349, 370
Knorr, G. W., 124
Knorria, 124–127, 174
K. imbricata, 255
K. mirabilis, 125
Knowlton, F. H., 350, 380
Kolbe, — 335
König, C., 209
Krasser, F., 181, 361, 409, 410, 474, 550, 552, 563
Kubart, B., 195
Kunze, — 307
Kurr, J. G., 431, 544
Laccopteris, 355–361, 411
L. Dunkeri, 361
L. elegans, 357
L. Goepperti, 357, 358
L. Muensteri, 374
Kaulfussia, 321, 434
Kerr, T., 164
Kidston, B. See note, page 609
Kidston, B. and J. Bennie, 191
Kidston, B. and D. T. Gwynne-Vaughan, 267, 314, 326, 329, 334, 338,
346, 377, 461, 472
Kidstonia heracleensis, 325, 340
Klukia, 348
K. exilis, 347–349, 370
Knorr, G. W., 124
Knorria, 124–127, 174
K. imbricata, 255
K. mirabilis, 125
Knowlton, F. H., 350, 380
Kolbe, — 335
König, C., 209
Krasser, F., 181, 361, 409, 410, 474, 550, 552, 563
Kubart, B., 195
Kunze, — 307
Kurr, J. G., 431, 544
Laccopteris, 355–361, 411
L. Dunkeri, 361
L. elegans, 357
L. Goepperti, 357, 358
L. Muensteri, 374
Page 693
L. polypodioides, 358–361, 374
L. Woodwardi, 360
Laminaria bulbosa, 71
Lamouroux, J., 572
Lang, W. H., 47, 49, 194, 195
Lavoisiera lycopodioides, 40, 75
Leckenby, J., 549
Leckenbya, 353
Leiodermaria, 198
Leiodermariae, 203
Leitgeb, H., 55
Lepidocarpon, 58, 92, 271–279
L. Lomaxi, 272–275
L. Wildianum, 274
Lepidodendron, 7–10, 27, 28, 34, 40–43, 55, 60–63, 71–77, 90–192,
196, 199–201, 207–211, 217–225, 230–249, 267–270, 312, 331
L. aculeatum, 142, 155, 156
L. anglicum, 264
L. australe, 178–181
L. brevifolium, 175, 176, 222
L. cyclostigma, 264
L. dichotomum, 178
L. discophorum, 209
L. esnostense, 99, 113, 139, 140, 266
L. fuliginosum, 21, 139, 141–162, 169, 175, 177, 191, 246, 262
L. gaspianum, 27
L. Woodwardi, 360
Laminaria bulbosa, 71
Lamouroux, J., 572
Lang, W. H., 47, 49, 194, 195
Lavoisiera lycopodioides, 40, 75
Leckenby, J., 549
Leckenbya, 353
Leiodermaria, 198
Leiodermariae, 203
Leitgeb, H., 55
Lepidocarpon, 58, 92, 271–279
L. Lomaxi, 272–275
L. Wildianum, 274
Lepidodendron, 7–10, 27, 28, 34, 40–43, 55, 60–63, 71–77, 90–192,
196, 199–201, 207–211, 217–225, 230–249, 267–270, 312, 331
L. aculeatum, 142, 155, 156
L. anglicum, 264
L. australe, 178–181
L. brevifolium, 175, 176, 222
L. cyclostigma, 264
L. dichotomum, 178
L. discophorum, 209
L. esnostense, 99, 113, 139, 140, 266
L. fuliginosum, 21, 139, 141–162, 169, 175, 177, 191, 246, 262
L. gaspianum, 27
Page 694
L. Harcourtii, 113, 139, 141, 143, 160–163, 170–178, 182, 189, 191,
262, 266, 275, 333
L. Hickii, 101, 166, 161
L. longifolium, 97
L. Losseni, 253
L. macrophyllum, 171, 176
L. mammillatum, 266
L. mundum, 241, 260–263
L. nothum, 180
L. obovatum, 139, 142, 154, 156
L. ottonis, 224
L. Peachii, 201
L. Pedroanum, 177, 178
L. punctatum, 371
L. rhodumnense, 140, 266, 333
L. saalfeldense, 141
L. selaginoides, 110
L. Spenceri, 192
L. Sternbergii, 97, 98, 110
L. tenerrimum, 260
L. vasculare, 109–123, 139, 145, 148, 152, 163, 166, 169, 189, 266,
334
L. Veltheimi, 172
L. Veltheimianum, 94, 99, 101, 125–129, 134, 141, 171–178, 187, 188,
209, 222, 223, 245, 249, 255
L. vereenigense, 105
L. volkmannianum, 105
262, 266, 275, 333
L. Hickii, 101, 166, 161
L. longifolium, 97
L. Losseni, 253
L. macrophyllum, 171, 176
L. mammillatum, 266
L. mundum, 241, 260–263
L. nothum, 180
L. obovatum, 139, 142, 154, 156
L. ottonis, 224
L. Peachii, 201
L. Pedroanum, 177, 178
L. punctatum, 371
L. rhodumnense, 140, 266, 333
L. saalfeldense, 141
L. selaginoides, 110
L. Spenceri, 192
L. Sternbergii, 97, 98, 110
L. tenerrimum, 260
L. vasculare, 109–123, 139, 145, 148, 152, 163, 166, 169, 189, 266,
334
L. Veltheimi, 172
L. Veltheimianum, 94, 99, 101, 125–129, 134, 141, 171–178, 187, 188,
209, 222, 223, 245, 249, 255
L. vereenigense, 105
L. volkmannianum, 105
Page 695
L. Williamsoni, 141, 142
L. Wortheni, 200, 201
L. Wükianum, 257
L. Wünschianum, 142, 152, 161–171, 187, 222, 223, 245
Lepidophloios, 104–109, 138, 139, 142, 153, 154, 157, 170, 171
L. Dessorti, 106
L. fuliginosus, 141
L. laricinus, 137
L. scoticus, 106, 135, 136, 185
Lepidophyllum, 181
Lepidospermae, 278
Lepidostrobus, 9, 39, 46, 60, 175, 181–192, 209, 248, 263, 272, 274,
496
L. Bailyanus, 257
L. Brownii, 189–191
L. fimbriatus, 46
L. foliaceus, 192, 193
L. insignis, 192, 193
L. oldhamius, 188
L. Olryi, 248–253
L. ornatus, 181, 187, 188
L. variabilis, 187, 188
L. Veltheimianus, 175
L. Wünschianus, 171
L. Zeilleri, 264
Leptophloeum rhombicum, 180
L. Wortheni, 200, 201
L. Wükianum, 257
L. Wünschianum, 142, 152, 161–171, 187, 222, 223, 245
Lepidophloios, 104–109, 138, 139, 142, 153, 154, 157, 170, 171
L. Dessorti, 106
L. fuliginosus, 141
L. laricinus, 137
L. scoticus, 106, 135, 136, 185
Lepidophyllum, 181
Lepidospermae, 278
Lepidostrobus, 9, 39, 46, 60, 175, 181–192, 209, 248, 263, 272, 274,
496
L. Bailyanus, 257
L. Brownii, 189–191
L. fimbriatus, 46
L. foliaceus, 192, 193
L. insignis, 192, 193
L. oldhamius, 188
L. Olryi, 248–253
L. ornatus, 181, 187, 188
L. variabilis, 187, 188
L. Veltheimianus, 175
L. Wünschianus, 171
L. Zeilleri, 264
Leptophloeum rhombicum, 180
Page 696
Leptosporangiate Filicales, 283–316, 324–394
Lesleya, 510, 517–519
L. Delafondi, 487, 518
L. ensis, 518
L. grandis, 518
L. simplicinervis, 518, 519
Leslie, T. N., 105, 178, 258, 508
Lesquereux, L., 77, 201, 419, 510, 517, 563, 570, 571, 573
Leuthardt, F., 332, 343, 353, 408, 410
Lhywd, E., 570
Lignier, O., 15, 23
Lindley, J., 67, 82, 84
Lindley, J. and W. Hutton, 128, 130, 135, 160, 209, 210, 221, 239, 249,
405, 421, 431, 481, 494, 530, 571
Lindman, C. A. M., 473
Lindsaya, 311–313, 377
Linopteris, 567, 572, 573
L. Brongniarti, 572
L. neuropteroides, 572, 573
L. obliqua, 572, 573
L. Schutzei, 572
Lithosmunda minor, 570
Logan, W. E., 228, 232
Lomatophloios macrolepidotus, 182
Lomatophloyos Wünschianus, 163
Lomatopteris, 544–546
Lesleya, 510, 517–519
L. Delafondi, 487, 518
L. ensis, 518
L. grandis, 518
L. simplicinervis, 518, 519
Leslie, T. N., 105, 178, 258, 508
Lesquereux, L., 77, 201, 419, 510, 517, 563, 570, 571, 573
Leuthardt, F., 332, 343, 353, 408, 410
Lhywd, E., 570
Lignier, O., 15, 23
Lindley, J., 67, 82, 84
Lindley, J. and W. Hutton, 128, 130, 135, 160, 209, 210, 221, 239, 249,
405, 421, 431, 481, 494, 530, 571
Lindman, C. A. M., 473
Lindsaya, 311–313, 377
Linopteris, 567, 572, 573
L. Brongniarti, 572
L. neuropteroides, 572, 573
L. obliqua, 572, 573
L. Schutzei, 572
Lithosmunda minor, 570
Logan, W. E., 228, 232
Lomatophloios macrolepidotus, 182
Lomatophloyos Wünschianus, 163
Lomatopteris, 544–546
Page 697
L. jurensis, 544, 545
L. Schimperi, 546
Lomax, J., 4, 240, 260
Lomax, J. and F. E. Weiss, 110
Lonchopteris, 494, 576
L. Bricei, 576
L. Mantelli, 494
L. rugosa, 576
L. virginiensis, 331, 332
Loxsoma, 293, 298, 312
Loxsomaceae, 293
Loxsomopsis costaricensis, 293
Lycopodiaceae, 33–49
Lycopodiales, 7, 10, 14, 30–279
Lycopodites, 28, 74–84
L. carbonaceus, 251
Lycopodiopsis Derbyi, 178
Lycopodites ciliatus, 79
L. elongatus, 79, 87
L. falcatus, 39, 76, 83, 84
L. Gutbieri, 79
L. lanceolatus, 81–83
L. macrophyllus, 79, 80, 85, 171
L. Milleri, 28
L. Reidii, 78, 79
L. scanicus, 83
L. Schimperi, 546
Lomax, J., 4, 240, 260
Lomax, J. and F. E. Weiss, 110
Lonchopteris, 494, 576
L. Bricei, 576
L. Mantelli, 494
L. rugosa, 576
L. virginiensis, 331, 332
Loxsoma, 293, 298, 312
Loxsomaceae, 293
Loxsomopsis costaricensis, 293
Lycopodiaceae, 33–49
Lycopodiales, 7, 10, 14, 30–279
Lycopodites, 28, 74–84
L. carbonaceus, 251
Lycopodiopsis Derbyi, 178
Lycopodites ciliatus, 79
L. elongatus, 79, 87
L. falcatus, 39, 76, 83, 84
L. Gutbieri, 79
L. lanceolatus, 81–83
L. macrophyllus, 79, 80, 85, 171
L. Milleri, 28
L. Reidii, 78, 79
L. scanicus, 83
Page 698
L. squamatus, 76
L. Stockii, 78
L. suissei, 85
L. tenerrimus, 84
L. Vanuxemi, 78
L. victoriae, 84
L. Zeilleri, 80
Lycopodium, 17, 24, 30–51, 56, 60, 63–66, 74–78, 82, 88, 96, 194,
195, 215, 251, 253, 263, 417
L. alopecuroides, 32, 82
L. alpinum, 32, 41
L. annotinum, 32
L. arboreum, 76
L. casuarinoides, 35, 39
L. cernuum, 31, 37, 39, 41–49, 93, 185, 194, 217
L. clavatum, 32, 40, 41, 46
L. complanatum, 87
L. cruentum, 32
L. Dalhousianum, 35, 38, 42
L. densum, 40
L. dichotomum, 34, 35, 41, 44, 46, 106
L. elongatum, 87
L. eryithraeum, 36
L. falcatum, 83
L. inundatum, 32, 43, 44
L. nummularifolium, 35, 38
L. Stockii, 78
L. suissei, 85
L. tenerrimus, 84
L. Vanuxemi, 78
L. victoriae, 84
L. Zeilleri, 80
Lycopodium, 17, 24, 30–51, 56, 60, 63–66, 74–78, 82, 88, 96, 194,
195, 215, 251, 253, 263, 417
L. alopecuroides, 32, 82
L. alpinum, 32, 41
L. annotinum, 32
L. arboreum, 76
L. casuarinoides, 35, 39
L. cernuum, 31, 37, 39, 41–49, 93, 185, 194, 217
L. clavatum, 32, 40, 41, 46
L. complanatum, 87
L. cruentum, 32
L. Dalhousianum, 35, 38, 42
L. densum, 40
L. dichotomum, 34, 35, 41, 44, 46, 106
L. elongatum, 87
L. eryithraeum, 36
L. falcatum, 83
L. inundatum, 32, 43, 44
L. nummularifolium, 35, 38
Page 699
L. obscurum, 38, 39, 93
L. Phlegmaria, 39, 44, 45, 78
L. primaevum, 86
L. rufescens, 34–36
L. saururus, 41, 42
L. selaginoides, 33
L. Selago, 4, 32, 34, 44, 87, 133, 256
L. serratum, 42
L. squarrosum, 36, 38, 39
L. tetragonum, 35, 39, 76
L. verticillatum, 39
L. volubile, 35, 39
Lycopsida, 312
Lycostrobus, 88–91
L. Scotti, 88–91
Lyginodendron, 140, 221, 270, 460, 510, 532, 565
Lygodium, 42, 287, 311, 446, 533, 534, 537
L. dichotomum, 337
L. Kaulfussi, 350
Lyon, F. M., 57, 58
McCoy, Sir F., 180, 491, 500, 512
McNicol, Mary, 461
Macroglossum alidae, 321
Macrotaeniopteris, 486
M. Feddeni, 489
L. Phlegmaria, 39, 44, 45, 78
L. primaevum, 86
L. rufescens, 34–36
L. saururus, 41, 42
L. selaginoides, 33
L. Selago, 4, 32, 34, 44, 87, 133, 256
L. serratum, 42
L. squarrosum, 36, 38, 39
L. tetragonum, 35, 39, 76
L. verticillatum, 39
L. volubile, 35, 39
Lycopsida, 312
Lycostrobus, 88–91
L. Scotti, 88–91
Lyginodendron, 140, 221, 270, 460, 510, 532, 565
Lygodium, 42, 287, 311, 446, 533, 534, 537
L. dichotomum, 337
L. Kaulfussi, 350
Lyon, F. M., 57, 58
McCoy, Sir F., 180, 491, 500, 512
McNicol, Mary, 461
Macroglossum alidae, 321
Macrotaeniopteris, 486
M. Feddeni, 489
Page 700
M. Wianamattae, 489
Macrozamia corallipes, 382
M. Fawcettiae, 382
Malaquin, M., 103
Marattia, 320, 408, 409, 417, 455, 485, 527
M. fraxinea, 317, 320, 528
M. Hookeri, 350, 411
M. Kaulfussii, 320, 397, 401, 411
Marattiaceae, 316–321, 351, 352, 395, 411, 434, 447, 565, 576
Marattiales, 316–321, 395–411
Marattiopsis, 407–409
Marattiopsis marantacea, 358, 408, 409
M. Muensteri, 320, 408, 409
Marion, A. F., 25, 26
Mariopteris, 351, 533–536
M. muricata, 534, 553
Marsilia, 473, 477–479
M. Andersoni, 474
M. cretacea, 474
M. Drummondi, 474
Marsilia elata, 474
M. Nathorsti, 474
M. perucensis, 474
M. quadrifoliata, 473
Marsiliaceae, 473–475
Marsilidium, 474
Macrozamia corallipes, 382
M. Fawcettiae, 382
Malaquin, M., 103
Marattia, 320, 408, 409, 417, 455, 485, 527
M. fraxinea, 317, 320, 528
M. Hookeri, 350, 411
M. Kaulfussii, 320, 397, 401, 411
Marattiaceae, 316–321, 351, 352, 395, 411, 434, 447, 565, 576
Marattiales, 316–321, 395–411
Marattiopsis, 407–409
Marattiopsis marantacea, 358, 408, 409
M. Muensteri, 320, 408, 409
Marion, A. F., 25, 26
Mariopteris, 351, 533–536
M. muricata, 534, 553
Marsilia, 473, 477–479
M. Andersoni, 474
M. cretacea, 474
M. Drummondi, 474
Marsilia elata, 474
M. Nathorsti, 474
M. perucensis, 474
M. quadrifoliata, 473
Marsiliaceae, 473–475
Marsilidium, 474
Page 701
M. speciosum, 474
Martin, W., 229
Martius, K. F. P. von, 420
Maslen, A. J., 187, 189, 190
Matonia, 291, 292, 298, 308, 316, 381, 420, 533
M. pectinata, 289–293, 300, 310, 314, 356, 357, 362, 363, 383
M. sarmentosa, 291, 310
Matonidium, 63, 310, 355, 359, 361–363
M. Althausii, 362, 363
M. Goepperti, 362
M. Wiesneri, 358, 363
Matonineae, 291–293, 355–363
Medullosa, 558, 567
M. anglica, 574
Megalopteris, 509
Megaloxylon, 331
Megaphyton, 413–415, 422
M. frondosum, 422
M. insigne, 421
M. McLayi, 422
Mellor, E. T. and T. N. Leslie, 233
Mertensides, 352
Mesostrobus, 195
Metaclepsydropsis, 447–450
M. duplex, 448–450
Mettenius, G., 223, 424, 425
Martin, W., 229
Martius, K. F. P. von, 420
Maslen, A. J., 187, 189, 190
Matonia, 291, 292, 298, 308, 316, 381, 420, 533
M. pectinata, 289–293, 300, 310, 314, 356, 357, 362, 363, 383
M. sarmentosa, 291, 310
Matonidium, 63, 310, 355, 359, 361–363
M. Althausii, 362, 363
M. Goepperti, 362
M. Wiesneri, 358, 363
Matonineae, 291–293, 355–363
Medullosa, 558, 567
M. anglica, 574
Megalopteris, 509
Megaloxylon, 331
Megaphyton, 413–415, 422
M. frondosum, 422
M. insigne, 421
M. McLayi, 422
Mellor, E. T. and T. N. Leslie, 233
Mertensides, 352
Mesostrobus, 195
Metaclepsydropsis, 447–450
M. duplex, 448–450
Mettenius, G., 223, 424, 425
Page 702
Miadesmia, 92, 275–279
M. membranacea, 275, 276
Microcachrys tetragona, 76
Microdictyon, 360
Miller, H., 27, 28, 532
Mixoneura, 555
Mixtae, 285
Mohl, H. von, 63
Mohlengraaff, G. A. F., 505
Mohria, 287
Möller, H., 392, 481
Monogramme, 306
Morris, J., 185, 191, 539
Münster, G. Graf zu, 24, 67–69
Muscites falcatus, 83
Myeloxylon, 556, 574
Nägeli, K. W. von, 55
Naiadaceae, 82
Naiadea acuminata, 81
N. lanceolata, 81
N. petiolata, 81
Naiadita, 82, 83
N. lanceolata, 81
Naiadites acuminatus, 81
Nathorst, A. G. See note, page 609
M. membranacea, 275, 276
Microcachrys tetragona, 76
Microdictyon, 360
Miller, H., 27, 28, 532
Mixoneura, 555
Mixtae, 285
Mohl, H. von, 63
Mohlengraaff, G. A. F., 505
Mohria, 287
Möller, H., 392, 481
Monogramme, 306
Morris, J., 185, 191, 539
Münster, G. Graf zu, 24, 67–69
Muscites falcatus, 83
Myeloxylon, 556, 574
Nägeli, K. W. von, 55
Naiadaceae, 82
Naiadea acuminata, 81
N. lanceolata, 81
N. petiolata, 81
Naiadita, 82, 83
N. lanceolata, 81
Naiadites acuminatus, 81
Nathorst, A. G. See note, page 609
Page 703
Nathorstia, 361, 410, 411
N. angustifolia, 410
N. latifolia, 410
Nephrodium filix-mas, 313
Nerium oleander, 567
Neuropteridium, 519–523, 525
N. grandifolium, 519, 522
N. intermedium, 521–523
N. Plantianum, 521
N. validum, 519–523, 525, 559
N. Voltzii, 523
Neuropteris, 398, 516, 526, 528, 552, 553, 556, 557, 565–572, 579,
580
N. cordata, var. angustifolia, 570
N. cordata, var. densineura, 524
N. conferta, 559
N. Goeppertiana, 340
N. Grangeri, 567
N. heterophylla, 351, 535, 568
N. hirsuta, 570
N. horrida, 571
N. macrophylla, 535, 569
N. pseudogigantea, 567
N. recentior, 339
N. Scheuchzeri, 535, 569–571
N. valida, 520
N. angustifolia, 410
N. latifolia, 410
Nephrodium filix-mas, 313
Nerium oleander, 567
Neuropteridium, 519–523, 525
N. grandifolium, 519, 522
N. intermedium, 521–523
N. Plantianum, 521
N. validum, 519–523, 525, 559
N. Voltzii, 523
Neuropteris, 398, 516, 526, 528, 552, 553, 556, 557, 565–572, 579,
580
N. cordata, var. angustifolia, 570
N. cordata, var. densineura, 524
N. conferta, 559
N. Goeppertiana, 340
N. Grangeri, 567
N. heterophylla, 351, 535, 568
N. hirsuta, 570
N. horrida, 571
N. macrophylla, 535, 569
N. pseudogigantea, 567
N. recentior, 339
N. Scheuchzeri, 535, 569–571
N. valida, 520
Page 704
Newberry, J. S., 431
Nilssonia, 485
Nipa, 309
Noeggerathia, 428–431, 560
N. acuminifissa, 563
N. flabellata, 431
N. foliosa, 429
N. obovata, 514
Noeggerathiopsis, 233, 516
Northampton, Marquis of, 190
Odontopteris, 516, 526, 528, 552–558, 560, 567, 571
O. cf. alpina, 555
O. Browni, 556
O. cycadea, 548
O. Fischeri, 556
O. genuina, 556, 557
O. jurensis, 544
O. macrophylla, 540
O. minor, 554, 555
O. osmundaeformis, 554
O. Plantiana, 519, 521
O. Reichiana, 555
O. Wortheni, 555
Oldham, R. D., 497, 501, 503, 505, 510
Oldham, T. and J. Morris, 84
Nilssonia, 485
Nipa, 309
Noeggerathia, 428–431, 560
N. acuminifissa, 563
N. flabellata, 431
N. foliosa, 429
N. obovata, 514
Noeggerathiopsis, 233, 516
Northampton, Marquis of, 190
Odontopteris, 516, 526, 528, 552–558, 560, 567, 571
O. cf. alpina, 555
O. Browni, 556
O. cycadea, 548
O. Fischeri, 556
O. genuina, 556, 557
O. jurensis, 544
O. macrophylla, 540
O. minor, 554, 555
O. osmundaeformis, 554
O. Plantiana, 519, 521
O. Reichiana, 555
O. Wortheni, 555
Oldham, R. D., 497, 501, 503, 505, 510
Oldham, T. and J. Morris, 84
Page 705
Oleandra, 301
O. neriiformis, 485, 492
Oleandridium, 485, 486
O. lentriculiforme, 492
Oligocarpia, 409
O. Brongniarti, 352, 364
O. Gutbieri, 352
Oliver, F. W., 437, 443, 532
Omphalophloios, 264–266
O. anglicus, 197, 264
Oncopteris, 372, 373
O. Nettvalli, 373
Onoclea hebraidica, 380
O. sensibilis, 380
O. struthiopteris, 303, 344, 502, 503
Onychiopsis, 369, 377–380
O. elongata, 378
O. Mantelli, 374, 378, 379
O. psilotoides, 378
Ophioglossaceae, 321–323, 434
Ophioglossales, 427–431
Ophioglossites antiqua, 428
Ophioglossum, 12, 321, 428
O. palmatum, 322
O. pendulum, 321
O. vulgatum, 321, 322
O. neriiformis, 485, 492
Oleandridium, 485, 486
O. lentriculiforme, 492
Oligocarpia, 409
O. Brongniarti, 352, 364
O. Gutbieri, 352
Oliver, F. W., 437, 443, 532
Omphalophloios, 264–266
O. anglicus, 197, 264
Oncopteris, 372, 373
O. Nettvalli, 373
Onoclea hebraidica, 380
O. sensibilis, 380
O. struthiopteris, 303, 344, 502, 503
Onychiopsis, 369, 377–380
O. elongata, 378
O. Mantelli, 374, 378, 379
O. psilotoides, 378
Ophioglossaceae, 321–323, 434
Ophioglossales, 427–431
Ophioglossites antiqua, 428
Ophioglossum, 12, 321, 428
O. palmatum, 322
O. pendulum, 321
O. vulgatum, 321, 322
Page 706
Osmunda, 267, 341, 567
O. cinnamomea, 286, 333, 339
O. Claytoniana, 314, 315, 333, 338
O. lignitum, 339
O. regalis, 285, 286, 331, 338, 342
O. Sturii, 339
Osmundaceae, 285, 286, 308, 314, 315, 324–346, 403, 409, 434, 443,
448, 461, 472
Osmundites Dowkeri, 338, 339
O. Dunlopi, 331–334, 337, 346
O. Gibbiana, 335, 339
O. Kolbei, 334–337
O. skidegatensis, 337, 338
O. Sturii, 339
Otopteris cuneata, 481
Otozamites Beani, 307
Ottokaria bengalensis, 498
O. ovalis, 498
Pachyphloeus tetragonus, 171
Pachypteris, 550, 552
P. dalmatica, 550
P. lanceolata, 550
Pachytesta, 574, 575
Palaeojulus dyadieus, 401, 402
Palaeopteris, 560, 561
P. hibernica var. minor, 563
O. cinnamomea, 286, 333, 339
O. Claytoniana, 314, 315, 333, 338
O. lignitum, 339
O. regalis, 285, 286, 331, 338, 342
O. Sturii, 339
Osmundaceae, 285, 286, 308, 314, 315, 324–346, 403, 409, 434, 443,
448, 461, 472
Osmundites Dowkeri, 338, 339
O. Dunlopi, 331–334, 337, 346
O. Gibbiana, 335, 339
O. Kolbei, 334–337
O. skidegatensis, 337, 338
O. Sturii, 339
Otopteris cuneata, 481
Otozamites Beani, 307
Ottokaria bengalensis, 498
O. ovalis, 498
Pachyphloeus tetragonus, 171
Pachypteris, 550, 552
P. dalmatica, 550
P. lanceolata, 550
Pachytesta, 574, 575
Palaeojulus dyadieus, 401, 402
Palaeopteris, 560, 561
P. hibernica var. minor, 563
Page 707
Palmatopteris, 533, 535, 537
P. furcata, 537
Parapecopteris, 398
P. neuropteroides, 398, 399
Parkeriaceae, 297
Parkinson, J., 181, 231, 413, 575
Paullinia thalictrifolia, 307
Peach, C. W., 530
Pecopteris, 298, 398, 494, 532, 541, 557, 576–580
P. abbreviata, 399
P. arborescens, 422, 529, 577, 578
P. bullatus, 352
P. caespitosa, 359
P. crenifolia, 359
P. cristata, 402
P. curtata, 339
P. cyathea, 422
P. dentata, 339, 404
P. denticulata, 343
P. exilis, 348
P. Huttoniana, 340
P. ligata, 359
P. Miltoni, 399
P. Phillipsii, 343
P. Pluckeneti, 419, 426, 576, 579
P. plumosa, 399, 404
P. furcata, 537
Parapecopteris, 398
P. neuropteroides, 398, 399
Parkeriaceae, 297
Parkinson, J., 181, 231, 413, 575
Paullinia thalictrifolia, 307
Peach, C. W., 530
Pecopteris, 298, 398, 494, 532, 541, 557, 576–580
P. abbreviata, 399
P. arborescens, 422, 529, 577, 578
P. bullatus, 352
P. caespitosa, 359
P. crenifolia, 359
P. cristata, 402
P. curtata, 339
P. cyathea, 422
P. dentata, 339, 404
P. denticulata, 343
P. exilis, 348
P. Huttoniana, 340
P. ligata, 359
P. Miltoni, 399
P. Phillipsii, 343
P. Pluckeneti, 419, 426, 576, 579
P. plumosa, 399, 404
Page 708
P. polymorpha, 579
P. recentior, 339
P. reticulata, 494
P. Rutimeyeri, 343
P. serra, 404
P. Sterzeli, 419, 426, 579
P. tenuis, 339
P. undans, 345
P. unita, 397, 579
P. whitbiensis, 339, 343, 344
P. Williamsonis, 339
P. Zippei, 354
Pelourde, F., 448
Penhallow, D. P., 28, 78, 337
Petver, — 231
Phanerosorus, 292
Phillips, J., 67, 348
Phlebopteris Phillipsi, 383
P. polypodioides, 358
P. propinqua, 358
P. Woodwardi, 360
Phragmites, 206
Phyllachne clavigera, 40
Phyllites nervulosis, 383
Phyllocladus, 542, 543
Phylloglossum, 30, 31, 33
P. recentior, 339
P. reticulata, 494
P. Rutimeyeri, 343
P. serra, 404
P. Sterzeli, 419, 426, 579
P. tenuis, 339
P. undans, 345
P. unita, 397, 579
P. whitbiensis, 339, 343, 344
P. Williamsonis, 339
P. Zippei, 354
Pelourde, F., 448
Penhallow, D. P., 28, 78, 337
Petver, — 231
Phanerosorus, 292
Phillips, J., 67, 348
Phlebopteris Phillipsi, 383
P. polypodioides, 358
P. propinqua, 358
P. Woodwardi, 360
Phragmites, 206
Phyllachne clavigera, 40
Phyllites nervulosis, 383
Phyllocladus, 542, 543
Phylloglossum, 30, 31, 33
Page 709
P. Drummondi, 33
Phytolithus cancellatus, 126
P. parmatus, 129
P. verrucosus, 231
Picea excelsa, 94
Pilularia, 67, 473
P. globulifera, 473
P. minuta, 473
P. pedunculata, 475
Pinakodendron, 264
P. musivum, 268
Pinus, 194
P. attenuata, 134
P. clausa, 134
P. excelsa, 174, 182
P. longifolia, 95, 98
Plagiogyria, 297
Plant, N., 177
Platyzoma, 291
P. microphylla, 312
Pleuromeia, 66–73, 91, 141
P. oculina, 69
P. Sternbergii, 68–70
Podocarpus, 210
P. dacrydioides, 75
Podoloma polypodioides, 394
Phytolithus cancellatus, 126
P. parmatus, 129
P. verrucosus, 231
Picea excelsa, 94
Pilularia, 67, 473
P. globulifera, 473
P. minuta, 473
P. pedunculata, 475
Pinakodendron, 264
P. musivum, 268
Pinus, 194
P. attenuata, 134
P. clausa, 134
P. excelsa, 174, 182
P. longifolia, 95, 98
Plagiogyria, 297
Plant, N., 177
Platyzoma, 291
P. microphylla, 312
Pleuromeia, 66–73, 91, 141
P. oculina, 69
P. Sternbergii, 68–70
Podocarpus, 210
P. dacrydioides, 75
Podoloma polypodioides, 394
Page 710
Poecilitostachys, 91
P. Hangi, 91
Polypodiaceae, 296, 375–380
Polypodium, 344
P. Billardieri, 302
P. carnosum, 301
P. heracleifolius, 383
P. oregonense, 377
P. quercifolium, 297, 298, 302, 303, 392, 528
P. vulgare, 301, 313, 577
Potonié, H. See p. 609
Prantl, K., 296
Presl, C. B., 127, 356, 390, 407, 477, 525, 572
Prestwick. J., 229
Primofilices, 433
Protophyllocladus, 543
Protopteris, 370–374, 390
P. punctata, 373–375
P. Sternbergii, 371
P. Witteana, 374, 375
Protorhipis asarifolius, 390
Protosalvinia, 476
Psaronieae, 412–426
Psaronius, 309, 372, 396, 412–426, 452
P. asterolithus, 416
P. brasiliensis, 420
P. Hangi, 91
Polypodiaceae, 296, 375–380
Polypodium, 344
P. Billardieri, 302
P. carnosum, 301
P. heracleifolius, 383
P. oregonense, 377
P. quercifolium, 297, 298, 302, 303, 392, 528
P. vulgare, 301, 313, 577
Potonié, H. See p. 609
Prantl, K., 296
Presl, C. B., 127, 356, 390, 407, 477, 525, 572
Prestwick. J., 229
Primofilices, 433
Protophyllocladus, 543
Protopteris, 370–374, 390
P. punctata, 373–375
P. Sternbergii, 371
P. Witteana, 374, 375
Protorhipis asarifolius, 390
Protosalvinia, 476
Psaronieae, 412–426
Psaronius, 309, 372, 396, 412–426, 452
P. asterolithus, 416
P. brasiliensis, 420
Page 711
P. coalescens, 416, 420
P. Cottai, 415
P. Cromptonensis, 413, 425
P. infarctus, 415–421, 424
P. musaeformis, 416, 420
P. Renaulti, 413, 418, 420, 425
P. Sterzeli, 419, 420
Pseudobornia, 11
P. ursina, 8
Psilophyton, 26–29
P. Dechianum, 27
P. filiformis, 24
P. princeps, 26–29
P. robustius, 27, 29
Psilotaceae, 12–15
Psilotales, 17–29
Psilotiphyllum, 26
Psilotites, 24, 25
P. filiformis, 24
P. lithranthracis, 25
P. unilateralis, 25
Psilotum, 12–24, 26, 29, 237
P. complanatum, 18
P. triquetrum, 17, 18, 20
Psygmophyllum, 431
Pteridospermaphyta, 278
P. Cottai, 415
P. Cromptonensis, 413, 425
P. infarctus, 415–421, 424
P. musaeformis, 416, 420
P. Renaulti, 413, 418, 420, 425
P. Sterzeli, 419, 420
Pseudobornia, 11
P. ursina, 8
Psilophyton, 26–29
P. Dechianum, 27
P. filiformis, 24
P. princeps, 26–29
P. robustius, 27, 29
Psilotaceae, 12–15
Psilotales, 17–29
Psilotiphyllum, 26
Psilotites, 24, 25
P. filiformis, 24
P. lithranthracis, 25
P. unilateralis, 25
Psilotum, 12–24, 26, 29, 237
P. complanatum, 18
P. triquetrum, 17, 18, 20
Psygmophyllum, 431
Pteridospermaphyta, 278
Page 712
Pteridosperms, 282, 395, 396, 403, 407, 426, 484–580
Pteridotheca, 325, 375
P. Butterworthi, 325
Pteris, 312, 580
P. aquilina, 305–309
P. arguta, 344
Pteropsida, 312
Ptilozamites, 539, 546, 547, 550
P. Heeri, 546–548
Ptychocarpus, 397, 411, 576, 578
P. oblongus, 397
P. unita, 397, 400, 578
Ptychopteris, 413, 414, 422–424
Rachiopteris antiqua, 449
R. corrugata, 450, 455, 460
R. cylindrica, 438
R. duplex, 447, 448
R. hirsuta, 436, 438, 442
R. inaequalis, 453, 454
R. insignis, 456
R. irregularis, 453, 454
R. ramosa, 436, 440
R. tridentata, 438
Raciborski, M., 339, 341, 348, 353, 543
Regnellidium, 473, 479
Pteridotheca, 325, 375
P. Butterworthi, 325
Pteris, 312, 580
P. aquilina, 305–309
P. arguta, 344
Pteropsida, 312
Ptilozamites, 539, 546, 547, 550
P. Heeri, 546–548
Ptychocarpus, 397, 411, 576, 578
P. oblongus, 397
P. unita, 397, 400, 578
Ptychopteris, 413, 414, 422–424
Rachiopteris antiqua, 449
R. corrugata, 450, 455, 460
R. cylindrica, 438
R. duplex, 447, 448
R. hirsuta, 436, 438, 442
R. inaequalis, 453, 454
R. insignis, 456
R. irregularis, 453, 454
R. ramosa, 436, 440
R. tridentata, 438
Raciborski, M., 339, 341, 348, 353, 543
Regnellidium, 473, 479
Page 713
R. diphyllum, 474, 479
Reinecke, F., 301
Reinsch, P. F., 192
Renault, B. See note, p. 609
Renault, B. and C. Grand’Eury, 219
Renault, B. and A. Roche, 204
Renault, B. and R. Zeiller, 510, 555,
560, 571, 577
Renaultia, 394, 406
Renier, A., 133
Rhacophyllum, 525
R. crispum, 526
Rhaciopterideae, 449
Rhacophyton condrusorum, 537
Rhacopteris, 426, 430, 431, 525, 563, 564
R. flabellata, 428
R. paniculifera, 428
Rhizodendron oppoliense, 375
Rhizomopteris, 381
R. cruciata, 388
R. major, 383
R. Schenki, 382
Rhodea, 27, 129, 196, 251
R. moravica, 364
R. patentissima, 364
Rhytidodendron, 251
Reinecke, F., 301
Reinsch, P. F., 192
Renault, B. See note, p. 609
Renault, B. and C. Grand’Eury, 219
Renault, B. and A. Roche, 204
Renault, B. and R. Zeiller, 510, 555,
560, 571, 577
Renaultia, 394, 406
Renier, A., 133
Rhacophyllum, 525
R. crispum, 526
Rhaciopterideae, 449
Rhacophyton condrusorum, 537
Rhacopteris, 426, 430, 431, 525, 563, 564
R. flabellata, 428
R. paniculifera, 428
Rhizodendron oppoliense, 375
Rhizomopteris, 381
R. cruciata, 388
R. major, 383
R. Schenki, 382
Rhodea, 27, 129, 196, 251
R. moravica, 364
R. patentissima, 364
Rhytidodendron, 251
Page 714
R. minutifolium, 251
Rhytidolepis, 198, 203, 222, 237
Richter, P. B., 390, 392, 393
Rodway, J., 93
Roehl, von, 571
Roemer, F., 571
Rotularia cuneifolia, 1
Royle, J. F., 501
Rudolph, K., 414, 417, 418
Ruffordia, 350
R. Goepperti, 349, 350
Saccoloma, 420
S. adiantoides, 424
Sadleria, 344
Salfeld, H., 545, 546
Sagenaria Bischofi, 69
S. Veltheimiana, 171
Sagenopteris, 431, 477–483
S. angustifolia, 478, 482
S. bilobata, 481
S. cuneata, 481
S. grandifolia, 482
S. longifolia, 482
S. Mantelli, 431, 482
S. Nathorsti, 482
Rhytidolepis, 198, 203, 222, 237
Richter, P. B., 390, 392, 393
Rodway, J., 93
Roehl, von, 571
Roemer, F., 571
Rotularia cuneifolia, 1
Royle, J. F., 501
Rudolph, K., 414, 417, 418
Ruffordia, 350
R. Goepperti, 349, 350
Saccoloma, 420
S. adiantoides, 424
Sadleria, 344
Salfeld, H., 545, 546
Sagenaria Bischofi, 69
S. Veltheimiana, 171
Sagenopteris, 431, 477–483
S. angustifolia, 478, 482
S. bilobata, 481
S. cuneata, 481
S. grandifolia, 482
S. longifolia, 482
S. Mantelli, 431, 482
S. Nathorsti, 482
Page 715
S. Nilssoniana, 478
S. Phillipsi, 431, 478–482
S. Phillipsi, f. pusilla, 482
S. rhoifolia, 479–482
Salvinia, 475
S. Alleni, 25
S. auriculata, 476
S. elliptica, 475
S. formosa, 476
S. natans, 475
S. reticulata, 25
S. Zeilleri, 476
Salviniaceae, 475–477
Samaropsis, 517
Saporta, le Marquis de, 66–68, 351, 360, 380, 545, 546, 548, 552
Schenk, A., 341, 352, 356, 358, 361, 363, 474, 482, 492, 544, 545, 549
Scheuchzer, J. T., 570, 574
Schimper, W. P., 25, 190, 257, 364, 376, 477, 486, 496, 523, 544, 546,
560, 579
Schimper, W. P. and A. Mougeot, 90, 519
Schizaea, 312
S. dichotoma, 307
S. elegans, 287, 307
S. pusilla, 287
Schizaeaceae, 286, 287, 346–351
Schizoneura, 523
S. Phillipsi, 431, 478–482
S. Phillipsi, f. pusilla, 482
S. rhoifolia, 479–482
Salvinia, 475
S. Alleni, 25
S. auriculata, 476
S. elliptica, 475
S. formosa, 476
S. natans, 475
S. reticulata, 25
S. Zeilleri, 476
Salviniaceae, 475–477
Samaropsis, 517
Saporta, le Marquis de, 66–68, 351, 360, 380, 545, 546, 548, 552
Schenk, A., 341, 352, 356, 358, 361, 363, 474, 482, 492, 544, 545, 549
Scheuchzer, J. T., 570, 574
Schimper, W. P., 25, 190, 257, 364, 376, 477, 486, 496, 523, 544, 546,
560, 579
Schimper, W. P. and A. Mougeot, 90, 519
Schizaea, 312
S. dichotoma, 307
S. elegans, 287, 307
S. pusilla, 287
Schizaeaceae, 286, 287, 346–351
Schizoneura, 523
Page 716
Schizopteris, 525
S. adnascens, 404
S. pinnata, 445, 464
S. lactuca, 526
Schizostachys frondosus, 464
Schlotheim, E. F. von, 413, 560, 574, 577
Schmalhausen, J., 257, 563
Schuster, J., 559
Schwarz, E. H. L., 259
Scleropteris, 552, 578
S. Pomelii, 552
Scolecopteris, 401, 402, 426
S. elegans, 400, 401
S. polymorpha, 401
Scolopendrium nigripes, 300, 513
S. vulgare, 513
Scott, D. H. See note, p. 609
Scott, Mrs D. H., 192, 469
Selaginella, 17, 30–33, 39, 49–58, 74–77, 85, 87, 88, 184, 215, 217,
263, 274–278
S. apus, 57
S. arabica, 80
S. Berthoudi, 84
S. caulescens, 85
S. erythropus, 53
S. grandis, 50–53, 75, 84
S. adnascens, 404
S. pinnata, 445, 464
S. lactuca, 526
Schizostachys frondosus, 464
Schlotheim, E. F. von, 413, 560, 574, 577
Schmalhausen, J., 257, 563
Schuster, J., 559
Schwarz, E. H. L., 259
Scleropteris, 552, 578
S. Pomelii, 552
Scolecopteris, 401, 402, 426
S. elegans, 400, 401
S. polymorpha, 401
Scolopendrium nigripes, 300, 513
S. vulgare, 513
Scott, D. H. See note, p. 609
Scott, Mrs D. H., 192, 469
Selaginella, 17, 30–33, 39, 49–58, 74–77, 85, 87, 88, 184, 215, 217,
263, 274–278
S. apus, 57
S. arabica, 80
S. Berthoudi, 84
S. caulescens, 85
S. erythropus, 53
S. grandis, 50–53, 75, 84
Page 717
S. inaequalifolia, 54
S. laevigata, 54
S. lepidophylla, 33
S. Martensii, 51, 53
S. revoluta, 80
S. rupestris, 52, 56, 57
S. spinosa, 31, 33, 50, 52, 53, 55, 278, 440
S. spinulosa, 23
S. Willdenowii, 52, 53
Selaginellaceae, 32, 33
Selaginellites, 74–77, 85–88
S. elongatus, 80, 87, 88
S. primaevus, 80, 86–88
S. suissei, 79, 85–88
Sellards, E. H., 486, 488, 538
Senftenbergia, 347, 404
S. elegans, 346, 364
S. plumosa, 404
Shattock, S. G., 131
Sigillaria, 39, 43, 44, 55, 61, 66, 69–75, 92, 98, 99, 105, 109, 110, 128,
140, 170, 196–226, 230, 231, 234, 238–240, 248, 266–269, 421
S. Brardi, 179, 180, 198, 200–203, 207, 210, 212, 213, 219, 224–226,
241, 261, 265–267
S. denudata, 203
S. discophora, 139, 209, 249
S. elegans, 160, 197, 217–224
S. elongata, 221, 222, 224
S. laevigata, 54
S. lepidophylla, 33
S. Martensii, 51, 53
S. revoluta, 80
S. rupestris, 52, 56, 57
S. spinosa, 31, 33, 50, 52, 53, 55, 278, 440
S. spinulosa, 23
S. Willdenowii, 52, 53
Selaginellaceae, 32, 33
Selaginellites, 74–77, 85–88
S. elongatus, 80, 87, 88
S. primaevus, 80, 86–88
S. suissei, 79, 85–88
Sellards, E. H., 486, 488, 538
Senftenbergia, 347, 404
S. elegans, 346, 364
S. plumosa, 404
Shattock, S. G., 131
Sigillaria, 39, 43, 44, 55, 61, 66, 69–75, 92, 98, 99, 105, 109, 110, 128,
140, 170, 196–226, 230, 231, 234, 238–240, 248, 266–269, 421
S. Brardi, 179, 180, 198, 200–203, 207, 210, 212, 213, 219, 224–226,
241, 261, 265–267
S. denudata, 203
S. discophora, 139, 209, 249
S. elegans, 160, 197, 217–224
S. elongata, 221, 222, 224
Page 718
S. Eugenii, 198
S. laevigata, 198, 200, 202
S. lepidodendrifolia, 200
S. McMurtriei, 199
S. mammillaris, 198, 199
S. Menardi, 224
S. minutifolia, 251
S. mutans, 224
S. oculina, 69–73
S. pachyderma, 198
S. rimosa, 248
S. rhomboidea, 203
S. rugosa, 197, 198, 200
S. scutellata, 196, 198, 212, 221, 222
S. spinulosa, 201, 212, 219, 224
S. Sternbergii, 69
S. Taylori, 209
S. tessellata, 197
S. vascularis, 110
S. Vanuxemi, 78
S. xylina, 221
Sigillariophyllum, 200
Sigillariopsis, 213, 214
S. Decaisnei, 213
S. sulcata, 214
Sigillariostrobus, 200, 215–217
S. laevigata, 198, 200, 202
S. lepidodendrifolia, 200
S. McMurtriei, 199
S. mammillaris, 198, 199
S. Menardi, 224
S. minutifolia, 251
S. mutans, 224
S. oculina, 69–73
S. pachyderma, 198
S. rimosa, 248
S. rhomboidea, 203
S. rugosa, 197, 198, 200
S. scutellata, 196, 198, 212, 221, 222
S. spinulosa, 201, 212, 219, 224
S. Sternbergii, 69
S. Taylori, 209
S. tessellata, 197
S. vascularis, 110
S. Vanuxemi, 78
S. xylina, 221
Sigillariophyllum, 200
Sigillariopsis, 213, 214
S. Decaisnei, 213
S. sulcata, 214
Sigillariostrobus, 200, 215–217
Page 719
S. bifidus, 26
S. ciliatus, 216
S. major, 217, 226
S. nobilis, 215
S. rhombibracteatus, 216
S. Teighemi, 215, 216
Simplices, 284, 298
Smith, G. O. and D. White, 28, 563
Solenites Murrayana, 67
Sollas, Igerna B. J., 82, 83
Solms-Laubach, H. Graf zu. See note, p. 609
Speirocarpus, 409
S. tenuifolius, 332
S. virginiensis, 332
Spencerites, 47, 49, 192–195, 263
S. insignis, 192–195
S. membranaceus, 195
Sphenolepidium, 39
Sphenophyllales, 1–16
Sphenophyllostachys, 7, 9
S. Dawsoni, 1, 2, 6, 14
S. fertilis, 4, 5, 12
S. Roemeri, 1–3, 14
Sphenophyllum, 1–7, 10–17, 21, 430
S. cuneifolium, 2
S. fertile, 4
S. ciliatus, 216
S. major, 217, 226
S. nobilis, 215
S. rhombibracteatus, 216
S. Teighemi, 215, 216
Simplices, 284, 298
Smith, G. O. and D. White, 28, 563
Solenites Murrayana, 67
Sollas, Igerna B. J., 82, 83
Solms-Laubach, H. Graf zu. See note, p. 609
Speirocarpus, 409
S. tenuifolius, 332
S. virginiensis, 332
Spencerites, 47, 49, 192–195, 263
S. insignis, 192–195
S. membranaceus, 195
Sphenolepidium, 39
Sphenophyllales, 1–16
Sphenophyllostachys, 7, 9
S. Dawsoni, 1, 2, 6, 14
S. fertilis, 4, 5, 12
S. Roemeri, 1–3, 14
Sphenophyllum, 1–7, 10–17, 21, 430
S. cuneifolium, 2
S. fertile, 4
Page 720
S. majus, 2, 3, 14
S. myriophyllum, 2
S. plurifoliatum, 2, 4
S. trichomatosum, 3, 4
Sphenopteris, 529–578
S. affinis, 530–532
S. arguta, 367, 368
S. caudata, 404
S. condrusorum, 537
S. coralloides, 470
S. cristata, 402, 366
S. dissecta, 532
S. elegans, 532
S. furcata, 529, 530, 535
S. Hoeninghausi, 532
S. hymenophylloides, 367, 368
S. Linkii, 532
S. Mantelli, 378
S. Matheti, 526
S. nephrocarpa, 367
S. obtusiloba, 529, 530
S. petiolata, 446
S. quinqueloba, 370
S. Rallii, 325, 402
S. stipata, 367
Spieker, T., 69
S. myriophyllum, 2
S. plurifoliatum, 2, 4
S. trichomatosum, 3, 4
Sphenopteris, 529–578
S. affinis, 530–532
S. arguta, 367, 368
S. caudata, 404
S. condrusorum, 537
S. coralloides, 470
S. cristata, 402, 366
S. dissecta, 532
S. elegans, 532
S. furcata, 529, 530, 535
S. Hoeninghausi, 532
S. hymenophylloides, 367, 368
S. Linkii, 532
S. Mantelli, 378
S. Matheti, 526
S. nephrocarpa, 367
S. obtusiloba, 529, 530
S. petiolata, 446
S. quinqueloba, 370
S. Rallii, 325, 402
S. stipata, 367
Spieker, T., 69
Page 721
Spiropteris, 579
Spirorbis, 102–104
Sprengel, A., 412
Stangeria paradoxa, 307
Staphylopteris Peachii, 531
Stauropteris, 433, 434, 465–469
S. burntislandica, 468, 469
S. oldhamia, 444, 450, 465–468
Steffensia silesiaca, 404
Steinhauer, H., 126–128, 228, 229
Stenzel, C. G., 375, 417, 418, 435, 450–453
Sternberg, C. von, 105, 110, 124, 126, 198, 413, 573
Sterzel, J. T., 366, 402, 412, 413
Stiehler, A. W., 494
Stigmaria, 66, 141, 153, 158, 226–247, 256, 261, 265
S. anabathra, 231
S. ficoides, 158, 159, 174, 226–232, 236–239, 246, 247, 256, 261
S. ficoides minuta, 255
S. flexuosa, 239
S. inaequalis, 174
S. radiculosa, 157–160
S. rimosa, 226
S. stellata, 247
Stigmariopsis, 205, 208, 233–239
S. anglica, 235
Stokes and Webb, 494
Spirorbis, 102–104
Sprengel, A., 412
Stangeria paradoxa, 307
Staphylopteris Peachii, 531
Stauropteris, 433, 434, 465–469
S. burntislandica, 468, 469
S. oldhamia, 444, 450, 465–468
Steffensia silesiaca, 404
Steinhauer, H., 126–128, 228, 229
Stenzel, C. G., 375, 417, 418, 435, 450–453
Sternberg, C. von, 105, 110, 124, 126, 198, 413, 573
Sterzel, J. T., 366, 402, 412, 413
Stiehler, A. W., 494
Stigmaria, 66, 141, 153, 158, 226–247, 256, 261, 265
S. anabathra, 231
S. ficoides, 158, 159, 174, 226–232, 236–239, 246, 247, 256, 261
S. ficoides minuta, 255
S. flexuosa, 239
S. inaequalis, 174
S. radiculosa, 157–160
S. rimosa, 226
S. stellata, 247
Stigmariopsis, 205, 208, 233–239
S. anglica, 235
Stokes and Webb, 494
Page 722
Stopes, Marie C., 436
Strasburger, E., 398
Stromatopteris, 291
Stur, D. See note, p. 609
Sturiella, 324
Sub-Sigillariae, 203
Sudworth, G. B., 134
Sykes, M. Gladys, 23, 47
Syringodendron, 198, 204, 205, 221, 226, 233, 238
S. esnostense, 204
S. striatum, 198
Szajnocha, L., 540
Taeniopteris, 485–494, 508, 509
T. Beyrichii, 494
T. Carnoti, 485, 488, 490
T. Carruthersi, 491
T. coriacea, 488, 490
T. Daintreei, 490, 491
T. gigantea, 489
T. immersa, 492
T. jejunata, 485, 488
T. Jourdyi, 489
T. lata, 489
T. Lescuriana, 487
T. major, 494
Strasburger, E., 398
Stromatopteris, 291
Stur, D. See note, p. 609
Sturiella, 324
Sub-Sigillariae, 203
Sudworth, G. B., 134
Sykes, M. Gladys, 23, 47
Syringodendron, 198, 204, 205, 221, 226, 233, 238
S. esnostense, 204
S. striatum, 198
Szajnocha, L., 540
Taeniopteris, 485–494, 508, 509
T. Beyrichii, 494
T. Carnoti, 485, 488, 490
T. Carruthersi, 491
T. coriacea, 488, 490
T. Daintreei, 490, 491
T. gigantea, 489
T. immersa, 492
T. jejunata, 485, 488
T. Jourdyi, 489
T. lata, 489
T. Lescuriana, 487
T. major, 494
Page 723
T. marantacea, 407, 408
T. mareyiaca, 491
T. missouriensis, 485
T. multinervis, 486–488
T. Newberriana, 488
T. spatulata, 489, 490
T. superba, 489
T. tenuinervis, 489, 492
T. virgulata, 492
T. vittata, 485, 489, 492–494
Tafalla graveolens, 40, 75
Tansley, A. G., 16, 280, 310, 440, 446
Telangium, 532
T. Scotti, 532
Teratophyllum aculeatum, 301, 405
Thamnocladus, 27
Thamnopteris, 326, 329–331, 334, 337, 338
T. Schlechtendalii, 329, 330, 448, 453
Thaumatopteris, 385
T. Brauniana, 385
T. Muensteri, 386
T. Schenki, 385
Theobroma, 209
Thinnfeldia, 537–552, 556
T. falcata, 540
T. Fontainei, 543
T. mareyiaca, 491
T. missouriensis, 485
T. multinervis, 486–488
T. Newberriana, 488
T. spatulata, 489, 490
T. superba, 489
T. tenuinervis, 489, 492
T. virgulata, 492
T. vittata, 485, 489, 492–494
Tafalla graveolens, 40, 75
Tansley, A. G., 16, 280, 310, 440, 446
Telangium, 532
T. Scotti, 532
Teratophyllum aculeatum, 301, 405
Thamnocladus, 27
Thamnopteris, 326, 329–331, 334, 337, 338
T. Schlechtendalii, 329, 330, 448, 453
Thaumatopteris, 385
T. Brauniana, 385
T. Muensteri, 386
T. Schenki, 385
Theobroma, 209
Thinnfeldia, 537–552, 556
T. falcata, 540
T. Fontainei, 543
Page 724
T. lancifolia, 539
T. odontopteroides, 538, 541–543, 546
T. rhomboidalis, 542–545
T. tenuinervis, 540
T. variabilis, 482, 543
Thoday, D., 6
Thomas, A. P. W., 12, 13, 17, 19, 23
Thomas, Ethel N., 239
Thompson, D’Arcy W., 131, 209
Thyrsopteris, 295, 296, 369
T. elegans, 289, 294, 308, 368
T. elongata, 378
T. Murrayana, 367
T. rarinervis, 369
T. schistorum, 366
Tmesipteris, 4, 12–25
T. tannensis, 17
Todea, 267, 337, 341, 468
T. australis, 346
T. barbara, 285, 286, 299, 314, 333, 339
T. hymenophylloides, 325
T. Lipoldi, 329
T. superba, 333
T. Wilkesiana, 286
Todeopsis primaeva, 324, 340
Todites, 339–343, 550
T. odontopteroides, 538, 541–543, 546
T. rhomboidalis, 542–545
T. tenuinervis, 540
T. variabilis, 482, 543
Thoday, D., 6
Thomas, A. P. W., 12, 13, 17, 19, 23
Thomas, Ethel N., 239
Thompson, D’Arcy W., 131, 209
Thyrsopteris, 295, 296, 369
T. elegans, 289, 294, 308, 368
T. elongata, 378
T. Murrayana, 367
T. rarinervis, 369
T. schistorum, 366
Tmesipteris, 4, 12–25
T. tannensis, 17
Todea, 267, 337, 341, 468
T. australis, 346
T. barbara, 285, 286, 299, 314, 333, 339
T. hymenophylloides, 325
T. Lipoldi, 329
T. superba, 333
T. Wilkesiana, 286
Todeopsis primaeva, 324, 340
Todites, 339–343, 550
Page 725
T. Roesserti, 346
T. Williamsoni, 332, 339–343, 352
Tracheotheca, 437, 443
Trautschold, H. and J. Auerbach, 260
Treub, M., 307, 308
Trichomanes, 293, 294, 303, 365, 452
T. Goebelianum, 300
T. radicans, 294, 315, 470
T. reniforme, 300, 310, 311, 315, 440, 571
T. scandens, 311
Trigonocarpon, 574
Triletes, 192, 215
Triplosporites, 190
Tubicaulis, 434–436, 443, 471
T. primarius, 443
T. solenites, 435
T. Sutcliffi, 436
Tylophora radiculosa, 157
Tympanophora racemosa, 367
T. simplex, 367
Ulodendron, 95, 128–135, 137, 138, 185, 209, 210, 251, 254, 255
U. minus, 209
Unger, F., 180, 412, 446, 449
Urnatopteris, 396, 407
Urophlyctites stigmariae, 247
T. Williamsoni, 332, 339–343, 352
Tracheotheca, 437, 443
Trautschold, H. and J. Auerbach, 260
Treub, M., 307, 308
Trichomanes, 293, 294, 303, 365, 452
T. Goebelianum, 300
T. radicans, 294, 315, 470
T. reniforme, 300, 310, 311, 315, 440, 571
T. scandens, 311
Trigonocarpon, 574
Triletes, 192, 215
Triplosporites, 190
Tubicaulis, 434–436, 443, 471
T. primarius, 443
T. solenites, 435
T. Sutcliffi, 436
Tylophora radiculosa, 157
Tympanophora racemosa, 367
T. simplex, 367
Ulodendron, 95, 128–135, 137, 138, 185, 209, 210, 251, 254, 255
U. minus, 209
Unger, F., 180, 412, 446, 449
Urnatopteris, 396, 407
Urophlyctites stigmariae, 247
Page 726
Variolaria ficoides, 231
Velenovský, J., 369, 372, 482, 543
Veronica, 75
Vertebraria, 497, 501–505
V. indica, 502, 503
Vittaria, 306
Volkmann, G. A., 124, 231
Walchia, 25
Wanklyn, A., 355
Ward, L. F., 278, 369
Watson, D. M. S., 131, 156, 161, 195, 261, 263, 278, 397
Weber, O. and J. T. Sterzel, 558
Weichselia, 494–496, 576
W. erratica, 495
W. Mantelli, 494–496
W. reticulata, 494
Weiss, C. E., 73, 107, 203, 253, 257, 264, 324, 429, 430, 486, 555–560
Weiss, F. E., 98, 101, 102, 138, 139, 151, 154, 157, 182, 240–242,
245–247, 261, 461
Welwitschia, 278
White, D., 27, 29, 201, 264, 265, 346, 377, 464, 485, 498, 513, 516,
560
Wickes, W. H., 82
Widdringtonites, 39
Wild, G. and J. Lomax, 271
Williamson, W. C. See note, p. 609
Velenovský, J., 369, 372, 482, 543
Veronica, 75
Vertebraria, 497, 501–505
V. indica, 502, 503
Vittaria, 306
Volkmann, G. A., 124, 231
Walchia, 25
Wanklyn, A., 355
Ward, L. F., 278, 369
Watson, D. M. S., 131, 156, 161, 195, 261, 263, 278, 397
Weber, O. and J. T. Sterzel, 558
Weichselia, 494–496, 576
W. erratica, 495
W. Mantelli, 494–496
W. reticulata, 494
Weiss, C. E., 73, 107, 203, 253, 257, 264, 324, 429, 430, 486, 555–560
Weiss, F. E., 98, 101, 102, 138, 139, 151, 154, 157, 182, 240–242,
245–247, 261, 461
Welwitschia, 278
White, D., 27, 29, 201, 264, 265, 346, 377, 464, 485, 498, 513, 516,
560
Wickes, W. H., 82
Widdringtonites, 39
Wild, G. and J. Lomax, 271
Williamson, W. C. See note, p. 609
Page 727
Williamson, W. C. and D. H. Scott, 6
Witham, H., 160
Woodwardia, 359
Woodwardites, 377
Wünsch, E. A., 163
Xenophyton radiculosum, 158
Xenopteris, 555
Yabe, H., 377, 481
Yokoyama, M., 349, 377
Young, G. and J. Bird, 83
Zalessky, M., 571
Zalesskya, 326–330, 332, 337, 338, 461
Z. diploxylon, 326–331
Z. gracilis, 326–331
Zeiller, R. See note, p. 609
Zeilleria, 407
Z. avoldensis, 407
Z. delicatula, 407
Zenker, J. C., 401
Zigno, A. de, 353, 390, 410, 478, 482, 546–550
Zygoptereae, 443–465
Zygopteris, 418, 449
Z. bibractensis, 453, 455
Z. Brongniarti, 450
Witham, H., 160
Woodwardia, 359
Woodwardites, 377
Wünsch, E. A., 163
Xenophyton radiculosum, 158
Xenopteris, 555
Yabe, H., 377, 481
Yokoyama, M., 349, 377
Young, G. and J. Bird, 83
Zalessky, M., 571
Zalesskya, 326–330, 332, 337, 338, 461
Z. diploxylon, 326–331
Z. gracilis, 326–331
Zeiller, R. See note, p. 609
Zeilleria, 407
Z. avoldensis, 407
Z. delicatula, 407
Zenker, J. C., 401
Zigno, A. de, 353, 390, 410, 478, 482, 546–550
Zygoptereae, 443–465
Zygopteris, 418, 449
Z. bibractensis, 453, 455
Z. Brongniarti, 450
Page 728
Z. Lacattii, 463
Z. pettycurensis, 447
Z. primaria, 443, 444, 446, 451
Z. Roemeri, 447, 448
Z. scandens, 450
Z. pettycurensis, 447
Z. primaria, 443, 444, 446, 451
Z. Roemeri, 447, 448
Z. scandens, 450
Page 729
FOOTNOTES:
[1] The full titles of books and papers referred to in footnotes distinguished by the
addition of A after the date are given in the Bibliography at the end of Volume i.
[2] Chap. xi.
[3] ibid. p. 405.
[4] Sternberg (23) A. p. 33, Pl. xxvi. figs. 4 a, 4 b.
[5] Scott (05) p. 34.
[6] Zeiller (88) A. Pl. lxii. figs. 2—4.
[7] Vol. i., p. 397.
[8] Kidston (01) p. 128, fig. 25; (02) p. 361, fig. 13.
[9] Bower (08) p. 404, fig. 221.
[10] Kidston (91) p. 59, Pl. I.; (01) p. 123, fig. 22.
[11] Scott (05).
[12] See also Browne, Lady Isabel (09) p. 4.
[13] Williamson and Scott (94) A. p. 911.
[14] Thoday (06).
[15] Scott (97) A.; see also Scott (00) p. 106.
[16] The term metaxylem may be conveniently applied to the primary xylem other than
protoxylem; the latter is usually but by no means invariably characterised by spiral
thickening bands.
[17] Scott (05) p. 21 (footnote).
[18] Vol. i. p. 354, fig. 95, C.
[19] Williamson (72) Pl. xliv. p. 297, figs. 29, 30.
[20] ‘Exarch’ denotes that the protoxylem is on the outside of the primary xylem;
‘endarch’ that it is on the inner edge or in a central position; ‘mesarch’ that it is internal,
either near the inner or the outer edge of the metaxylem.
[21] Nathorst (02) p. 24.
[22] Heer (71) p. 32, Pls. i—vi.
[23] Scott (07) p. 155.
[24] Thomas, A. P. W. (02) p. 350.
[25] Bower (04) p. 227; (08) p. 424.
[26] See p. 19.
[27] Scott (00) p. 499.
[28] Bower (94) p. 545.
[1] The full titles of books and papers referred to in footnotes distinguished by the
addition of A after the date are given in the Bibliography at the end of Volume i.
[2] Chap. xi.
[3] ibid. p. 405.
[4] Sternberg (23) A. p. 33, Pl. xxvi. figs. 4 a, 4 b.
[5] Scott (05) p. 34.
[6] Zeiller (88) A. Pl. lxii. figs. 2—4.
[7] Vol. i., p. 397.
[8] Kidston (01) p. 128, fig. 25; (02) p. 361, fig. 13.
[9] Bower (08) p. 404, fig. 221.
[10] Kidston (91) p. 59, Pl. I.; (01) p. 123, fig. 22.
[11] Scott (05).
[12] See also Browne, Lady Isabel (09) p. 4.
[13] Williamson and Scott (94) A. p. 911.
[14] Thoday (06).
[15] Scott (97) A.; see also Scott (00) p. 106.
[16] The term metaxylem may be conveniently applied to the primary xylem other than
protoxylem; the latter is usually but by no means invariably characterised by spiral
thickening bands.
[17] Scott (05) p. 21 (footnote).
[18] Vol. i. p. 354, fig. 95, C.
[19] Williamson (72) Pl. xliv. p. 297, figs. 29, 30.
[20] ‘Exarch’ denotes that the protoxylem is on the outside of the primary xylem;
‘endarch’ that it is on the inner edge or in a central position; ‘mesarch’ that it is internal,
either near the inner or the outer edge of the metaxylem.
[21] Nathorst (02) p. 24.
[22] Heer (71) p. 32, Pls. i—vi.
[23] Scott (07) p. 155.
[24] Thomas, A. P. W. (02) p. 350.
[25] Bower (04) p. 227; (08) p. 424.
[26] See p. 19.
[27] Scott (00) p. 499.
[28] Bower (94) p. 545.
Page 730
[29] Thomas (02). See also Sykes (08).
[30] Sykes (08).
[31] Boodle (04); see postea p. 21.
[32] Bower (08) p. 426.
[33] Lignier (03); (08).
[34] Tansley (08) p. 26, who refers to similar views held by Potonié and by Hallier.
[35] On the morphology of Sporangiophores, see also Benson (082) and Scott, D. H. (09)
p. 623.
[36] Scott (00).
[37] Thomas (02).
[38] Bower (08) p. 398.
[39] Dangeard (91) and Bertrand, C. E. (81) recognise other species of Tmesipteris, but
it is doubtful how far such differences as exist are worthy of specific recognition.
[40] Baker (87) A. p. 30.
[41] Thomas (02) p. 349.
[42] Another form of abnormality in the sporophylls of Psilotum has recently been
described by Miss Sykes. Sykes (082).
[43] Bertrand, C. E. (81); Ford (04).
[44] Boodle (04).
[45] See p. 150.
[46] Bertrand (81); Jennings and Hall (91).
[47] Sykes (08).
[48] ibid. (08).
[49] Lignier (08).
[50] Bower (94); (08).
[51] Bertrand (81) p. 254.
[52] Münster (42) p. 108, Pl. xiii. fig. 11; Pl. xv. fig. 20.
[53] Schimper (70) A. p. 75.
[54] Goldenberg (55) p. 13, Pl. ii. fig 7.
[55] Kidston (862).
[56] Hollick (94) p. 255, figs. 12, 13.
[57] Lesquereux (78) Pl. v. fig. 11.
[58] Since this was written I have had an opportunity of seeing a leaf labelled
Tmesipteris from the Tertiary plant-beds of Florissant in a collection recently acquired
by the British Museum: the specimen bears no resemblance to a leaf of the recent genus.
[59] Marion (90).
[60] Potonié (93) A. p. 197, Pls. xxvii., xxviii., xxxiii.
[61] Potonié (91); (93) A. p. 197.
[62] Geinitz (73) p. 700, Pl. iii. figs. 5–7.
[30] Sykes (08).
[31] Boodle (04); see postea p. 21.
[32] Bower (08) p. 426.
[33] Lignier (03); (08).
[34] Tansley (08) p. 26, who refers to similar views held by Potonié and by Hallier.
[35] On the morphology of Sporangiophores, see also Benson (082) and Scott, D. H. (09)
p. 623.
[36] Scott (00).
[37] Thomas (02).
[38] Bower (08) p. 398.
[39] Dangeard (91) and Bertrand, C. E. (81) recognise other species of Tmesipteris, but
it is doubtful how far such differences as exist are worthy of specific recognition.
[40] Baker (87) A. p. 30.
[41] Thomas (02) p. 349.
[42] Another form of abnormality in the sporophylls of Psilotum has recently been
described by Miss Sykes. Sykes (082).
[43] Bertrand, C. E. (81); Ford (04).
[44] Boodle (04).
[45] See p. 150.
[46] Bertrand (81); Jennings and Hall (91).
[47] Sykes (08).
[48] ibid. (08).
[49] Lignier (08).
[50] Bower (94); (08).
[51] Bertrand (81) p. 254.
[52] Münster (42) p. 108, Pl. xiii. fig. 11; Pl. xv. fig. 20.
[53] Schimper (70) A. p. 75.
[54] Goldenberg (55) p. 13, Pl. ii. fig 7.
[55] Kidston (862).
[56] Hollick (94) p. 255, figs. 12, 13.
[57] Lesquereux (78) Pl. v. fig. 11.
[58] Since this was written I have had an opportunity of seeing a leaf labelled
Tmesipteris from the Tertiary plant-beds of Florissant in a collection recently acquired
by the British Museum: the specimen bears no resemblance to a leaf of the recent genus.
[59] Marion (90).
[60] Potonié (93) A. p. 197, Pls. xxvii., xxviii., xxxiii.
[61] Potonié (91); (93) A. p. 197.
[62] Geinitz (73) p. 700, Pl. iii. figs. 5–7.
Page 731
[63] Seward and Gowan (00) p. 137; Seward and Ford (06) p. 374.
[64] Dawson (59) A. p. 478, fig. 1.
[65] ibid. (71) A. p. 38.
[66] Solms-Laubach (95) A.
[67] Dawson (71) A. Cf. Pl. xi. figs. 131, 134, etc.
[68] Carruthers (73).
[69] Goeppert (52) A.
[70] Carruthers (73).
[71] White (02).
[72] Crépin (75).
[73] Stur (75) A. p. 33.
[74] Carruthers (73).
[75] Gilkinet (75) figs. 2–5.
[76] Penhallow (92) p. 8.
[77] Smith and White (05) p. 58, Pls. v. vi.
[78] Kidston (862) p. 232.
[79] Stur (81) Pls. iii. iv.
[80] Jahn (03) p. 77.
[81] Smith and White (05) p. 63.
[82] Nathorst (02) p. 15, Pl. i. figs. 18–35.
[83] For a general account of recent Lycopodiales see Pritzel (02); Campbell (05);
Bower (08).
[84] Bruchmann (97).
[85] Treub (84–90); see also Lang (99) and Bruchmann (98).
[86] See Baker (87) A.
[87] The Rose of Jericho is Anastatica Hierochuntina L. a Cruciferous plant.
[88] Baker (87) A. p. 34.
[89] Vines (88).
[90] Scott and Hill (00).
[91] For Phylloglossum, see Bertrand (82); Bower (94), (08); Campbell (05).
[92] Treub (84–90); Bruchmann (98); Lang (99).
[93] Sykes (083).
[94] Bommer (03) Pl. ix. figs. 140, 141.
[95] Hooker (48) p. 423, figs. 12–14.
[96] Jones (05).
[97] Boodle (01) Pl. xix.
[98] This species is figured under the name Lycopodium crassum by Hooker and
Greville (31) Pl. 224. See also Brongniart (37) Pl. i. fig. 1.
[64] Dawson (59) A. p. 478, fig. 1.
[65] ibid. (71) A. p. 38.
[66] Solms-Laubach (95) A.
[67] Dawson (71) A. Cf. Pl. xi. figs. 131, 134, etc.
[68] Carruthers (73).
[69] Goeppert (52) A.
[70] Carruthers (73).
[71] White (02).
[72] Crépin (75).
[73] Stur (75) A. p. 33.
[74] Carruthers (73).
[75] Gilkinet (75) figs. 2–5.
[76] Penhallow (92) p. 8.
[77] Smith and White (05) p. 58, Pls. v. vi.
[78] Kidston (862) p. 232.
[79] Stur (81) Pls. iii. iv.
[80] Jahn (03) p. 77.
[81] Smith and White (05) p. 63.
[82] Nathorst (02) p. 15, Pl. i. figs. 18–35.
[83] For a general account of recent Lycopodiales see Pritzel (02); Campbell (05);
Bower (08).
[84] Bruchmann (97).
[85] Treub (84–90); see also Lang (99) and Bruchmann (98).
[86] See Baker (87) A.
[87] The Rose of Jericho is Anastatica Hierochuntina L. a Cruciferous plant.
[88] Baker (87) A. p. 34.
[89] Vines (88).
[90] Scott and Hill (00).
[91] For Phylloglossum, see Bertrand (82); Bower (94), (08); Campbell (05).
[92] Treub (84–90); Bruchmann (98); Lang (99).
[93] Sykes (083).
[94] Bommer (03) Pl. ix. figs. 140, 141.
[95] Hooker (48) p. 423, figs. 12–14.
[96] Jones (05).
[97] Boodle (01) Pl. xix.
[98] This species is figured under the name Lycopodium crassum by Hooker and
Greville (31) Pl. 224. See also Brongniart (37) Pl. i. fig. 1.
Page 732
[99] Hegelmaier (72). See also Hill, T.G. (06) p. 269; this author draws attention to the
fact that in some species of Lycopodium the mucilage canals are confined to the
sporophylls.
[100] Professor Yapp has drawn my attention to the very close anatomical resemblance
between a specimen of Lycopodium salakense obtained by him from Gunong Inas in the
Malay Peninsula and L. cernuum as represented in fig. 125, H and I.
[101] Jones (05).
[102] Strasburger (73) p. 109; Brongniart (37) Pl. 8; (39) A. Pl. 32: Brongniart figures
stems of L. Phlegmaria and other species showing roots in the cortex. See also
Goldenberg (55); Bruchmann (74); Saxelby (08).
[103] Since this was written a comparative account of the sporophylls of Lycopodium
has been published by Miss Sykes. {Sykes (083).}
[104] Bower (94) p. 514; (08).
[105] Seward and Ford (06).
[106] Goebel (05) p. 579.
[107] Bower (94).
[108] ibid. (94) Pl. xlviii.
[109] Kidston (83) Pl. xxxi. figs. 2–4.
[110] Lang (08).
[111] See page 192, and Watson (09).
[112] Lang (08) p. 357.
[113] Bruchmann (97).
[114] Gard. Chron. (82).
[115] Harvey-Gibson (02).
[116] ibid. (94) (97) (02).
[117] Bower (93).
[118] Harvey-Gibson (94) p. 152.
[119] ibid. (94) p. 194; Scott (96) p. 9.
[120] Bruchmann (97).
[121] The term solenostele, first used by Van Tieghem and revived by Gwynne-Vaughan,
may be applied to a stem in which the vascular tissue has the form of a hollow cylinder
with phloem and endodermis on each side of the xylem. As each leaf-trace is given off
the continuity of the vascular tube is interrupted. See Gwynne-Vaughan (01) p. 73.
[122] Harvey-Gibson (94) Pl. xii, fig. 93.
[123] Harvey-Gibson (02).
[124] ibid. (97).
[125] ibid. (96).
[126] Bower (08) p. 315.
[127] Hieronymus (02).
[128] Goebel (05) p. 581.
fact that in some species of Lycopodium the mucilage canals are confined to the
sporophylls.
[100] Professor Yapp has drawn my attention to the very close anatomical resemblance
between a specimen of Lycopodium salakense obtained by him from Gunong Inas in the
Malay Peninsula and L. cernuum as represented in fig. 125, H and I.
[101] Jones (05).
[102] Strasburger (73) p. 109; Brongniart (37) Pl. 8; (39) A. Pl. 32: Brongniart figures
stems of L. Phlegmaria and other species showing roots in the cortex. See also
Goldenberg (55); Bruchmann (74); Saxelby (08).
[103] Since this was written a comparative account of the sporophylls of Lycopodium
has been published by Miss Sykes. {Sykes (083).}
[104] Bower (94) p. 514; (08).
[105] Seward and Ford (06).
[106] Goebel (05) p. 579.
[107] Bower (94).
[108] ibid. (94) Pl. xlviii.
[109] Kidston (83) Pl. xxxi. figs. 2–4.
[110] Lang (08).
[111] See page 192, and Watson (09).
[112] Lang (08) p. 357.
[113] Bruchmann (97).
[114] Gard. Chron. (82).
[115] Harvey-Gibson (02).
[116] ibid. (94) (97) (02).
[117] Bower (93).
[118] Harvey-Gibson (94) p. 152.
[119] ibid. (94) p. 194; Scott (96) p. 9.
[120] Bruchmann (97).
[121] The term solenostele, first used by Van Tieghem and revived by Gwynne-Vaughan,
may be applied to a stem in which the vascular tissue has the form of a hollow cylinder
with phloem and endodermis on each side of the xylem. As each leaf-trace is given off
the continuity of the vascular tube is interrupted. See Gwynne-Vaughan (01) p. 73.
[122] Harvey-Gibson (94) Pl. xii, fig. 93.
[123] Harvey-Gibson (02).
[124] ibid. (97).
[125] ibid. (96).
[126] Bower (08) p. 315.
[127] Hieronymus (02).
[128] Goebel (05) p. 581.
Page 733
[129] Lyon (01) p. 135.
[130] See p. 271.
[131] Campbell (05) p. 522.
[132] Motelay and Vendryès (82).
[133] Campbell (05) p. 561.
[134] Scott and Hill (00).
[135] Motelay and Vendryès (82) Pls. xvi, xvii.
[136] Braun (63).
[137] Hill, T. G. (04) (06).
[138] For figures, see Motelay and Vendryès (82); Bennie and Kidston (88) Pl. vi.
[139] Solms-Laubach (02).
[140] See Von Mohl (40); Farmer (90).
[141] Von Mohl (40).
[142] Hofmeister (62).
[143] Farmer (90); Scott and Hill (00).
[144] Miss Stokey (09), in a paper which appeared since this account was written,
criticises the conclusions of Scott and Hill (00).
[145] Von Mohl (40).
[146] Saporta (94) p. 134, Pls. xxiv. xxv. xxvii.
[147] Münster (42) p. 107, Pl. iv. fig. 4.
[148] Phillips (29) A Pl x. fig. 12.
[149] Lindley and Hutton A (34) Pl. cxxi.
[150] Nathorst (06); Seward (00) p. 278.
[151] Saporta (88) p. 28, Pl. ii. pp. 16–20.
[152] Heer (76) A.
[153] Corda, in Germar (52).
[154] Münster (42) A.
[155] Solms-Laubach (99).
[156] Germar (52).
[157] Bischof (53).
[158] Potonié (01) p. 754; (04) Lief ii.
[159] Goeppert, in Römer (54) Pl. xv. fig. 7.
[160] Spieker (53).
[161] Potonié (loc. cit.).
[162] Barber (89) Pls. v. vi.
[163] Fitting (07).
[164] Potonié (04) Lief ii.
[130] See p. 271.
[131] Campbell (05) p. 522.
[132] Motelay and Vendryès (82).
[133] Campbell (05) p. 561.
[134] Scott and Hill (00).
[135] Motelay and Vendryès (82) Pls. xvi, xvii.
[136] Braun (63).
[137] Hill, T. G. (04) (06).
[138] For figures, see Motelay and Vendryès (82); Bennie and Kidston (88) Pl. vi.
[139] Solms-Laubach (02).
[140] See Von Mohl (40); Farmer (90).
[141] Von Mohl (40).
[142] Hofmeister (62).
[143] Farmer (90); Scott and Hill (00).
[144] Miss Stokey (09), in a paper which appeared since this account was written,
criticises the conclusions of Scott and Hill (00).
[145] Von Mohl (40).
[146] Saporta (94) p. 134, Pls. xxiv. xxv. xxvii.
[147] Münster (42) p. 107, Pl. iv. fig. 4.
[148] Phillips (29) A Pl x. fig. 12.
[149] Lindley and Hutton A (34) Pl. cxxi.
[150] Nathorst (06); Seward (00) p. 278.
[151] Saporta (88) p. 28, Pl. ii. pp. 16–20.
[152] Heer (76) A.
[153] Corda, in Germar (52).
[154] Münster (42) A.
[155] Solms-Laubach (99).
[156] Germar (52).
[157] Bischof (53).
[158] Potonié (01) p. 754; (04) Lief ii.
[159] Goeppert, in Römer (54) Pl. xv. fig. 7.
[160] Spieker (53).
[161] Potonié (loc. cit.).
[162] Barber (89) Pls. v. vi.
[163] Fitting (07).
[164] Potonié (04) Lief ii.
Page 734
[165] Weiss, C. E. (86).
[166] Fliche (03).
[167] Vol. i, p. 300.
[168] Halle (07) p. 1.
[169] Feistmantel (75) A. p. 183, Pl. xxx. pp. 1 and 2.
[170] Germar (49) Pl. xxvi; Geinitz (55) A. Pl. i. pp. 5, 6.
[171] Bommer (03) p. 29, Pl. ix, figs. 138–141.
[172] Solms-Laubach (91) A. p. 137.
[173] Zeiller (06) p. 140.
[174] Halle (07).
[175] Brongniart (22) A. p. 304, Pl. vi, fig. 1.
[176] Brongniart (28) A. p. 83.
[177] Brongniart (49) A. p. 40.
[178] Goldenberg (55) p. 9.
[179] Lesquereux (84) A. p. 777.
[180] Kidston (863) p. 561.
[181] Halle (07).
[182] Renault (69) p. 178, Pls. xii–xiv.
[183] Renault (96) A. p. 249.
[184] Kidston (863).
[185] Goeppert (52) A.
[186] Kidston (01) p. 38.
[187] Kidston (84) Pl. v; (01) p. 37.
[188] Bower (08) p. 298, fig. 147.
[189] Solms-Laubach (91) A. p. 186.
[190] Penhallow (92) Pl. i. fig. 2, p. 8.
[191] Goeppert (52) p. 440.
[192] Kidston (94) A. p. 254.
[193] Geinitz (55) A. p. 32, Pl. i. fig. 1.
[194] page 88.
[195] Kidston (01) p. 36, fig. 2, B.
[196] Kidston (01) p. 37, fig. 2, A.
[197] Goldenberg (55) Pl. i. fig. 5.
[198] Halle (07) Pl. i. fig. 5.
[199] page 89.
[200] Halle (07).
[201] Brodie (45) p. 93.
[166] Fliche (03).
[167] Vol. i, p. 300.
[168] Halle (07) p. 1.
[169] Feistmantel (75) A. p. 183, Pl. xxx. pp. 1 and 2.
[170] Germar (49) Pl. xxvi; Geinitz (55) A. Pl. i. pp. 5, 6.
[171] Bommer (03) p. 29, Pl. ix, figs. 138–141.
[172] Solms-Laubach (91) A. p. 137.
[173] Zeiller (06) p. 140.
[174] Halle (07).
[175] Brongniart (22) A. p. 304, Pl. vi, fig. 1.
[176] Brongniart (28) A. p. 83.
[177] Brongniart (49) A. p. 40.
[178] Goldenberg (55) p. 9.
[179] Lesquereux (84) A. p. 777.
[180] Kidston (863) p. 561.
[181] Halle (07).
[182] Renault (69) p. 178, Pls. xii–xiv.
[183] Renault (96) A. p. 249.
[184] Kidston (863).
[185] Goeppert (52) A.
[186] Kidston (01) p. 38.
[187] Kidston (84) Pl. v; (01) p. 37.
[188] Bower (08) p. 298, fig. 147.
[189] Solms-Laubach (91) A. p. 186.
[190] Penhallow (92) Pl. i. fig. 2, p. 8.
[191] Goeppert (52) p. 440.
[192] Kidston (94) A. p. 254.
[193] Geinitz (55) A. p. 32, Pl. i. fig. 1.
[194] page 88.
[195] Kidston (01) p. 36, fig. 2, B.
[196] Kidston (01) p. 37, fig. 2, A.
[197] Goldenberg (55) Pl. i. fig. 5.
[198] Halle (07) Pl. i. fig. 5.
[199] page 89.
[200] Halle (07).
[201] Brodie (45) p. 93.
Page 735
[202] Buckman in Murchison (45) p. 6.
[203] Buckman (50) p. 415, fig. 2.
[204] Buckman (50) p. 415, fig. 4.
[205] Wickes (00) p. 422.
[206] Sollas (01).
[207] Seward (04) p. 14, Pl. ii. figs. 2, 3.
[208] Vol. i. p. 240.
[209] Sollas (01) p. 311.
[210] Seward (04) p. 14.
[211] Halle (07) p. 14, Pl. iii. figs. 6–12.
[212] Lindley and Hutton (31) A. Pl. lxi.
[213] Sternberg (38) A. p. 38.
[214] Schimper (70) A. p. 9.
[215] Young and Bird (22) A. Pl. ii. fig. 7.
[216] No. 39314, Brit. Mus.
[217] Möller (02) Pl. vi. fig. 21.
[218] Seward (042) p. 161, Pl. viii. figs. 2–4. The drawing is reproduced twice natural
size.
[219] Oldham and Morris (63) Pls. xxxiii. xxxv.
[220] Feistmantel (77) p. 87.
[221] Heer (76) Pl. xv. figs. 1–8.
[222] Nathorst (90) A. Pl. ii. fig. 3. Saporta (94) Pls. xxiii.-xxvi. Knowlton (98) p. 136.
[223] Lesquereux (78) Pl. v. fig. 12. See also Knowlton loc. cit.
[224] Zeiller (06) p. 141, Pls. xxxix. xli.
[225] Zeiller (00) p. 1077.
[226] Bennie and Kidston (88) Pl. vi. fig. 22.
[227] Goldenberg (55) Pl. i. fig. 3.
[228] Schimper (70) A. Pl. lvii. fig. 2.
[229] Halle (07).
[230] Goldenberg (55) Pl. i. fig. 2.
[231] Schimper (70) A. p. 10.
[232] Nathorst (08).
[233] Nathorst (022) p. 5, Pl. i. fig. 1.
[234] Fliche (03).
[235] Fliche (09).
[236] Scott (01).
[237] Rodway (95) A. p. 153.
[203] Buckman (50) p. 415, fig. 2.
[204] Buckman (50) p. 415, fig. 4.
[205] Wickes (00) p. 422.
[206] Sollas (01).
[207] Seward (04) p. 14, Pl. ii. figs. 2, 3.
[208] Vol. i. p. 240.
[209] Sollas (01) p. 311.
[210] Seward (04) p. 14.
[211] Halle (07) p. 14, Pl. iii. figs. 6–12.
[212] Lindley and Hutton (31) A. Pl. lxi.
[213] Sternberg (38) A. p. 38.
[214] Schimper (70) A. p. 9.
[215] Young and Bird (22) A. Pl. ii. fig. 7.
[216] No. 39314, Brit. Mus.
[217] Möller (02) Pl. vi. fig. 21.
[218] Seward (042) p. 161, Pl. viii. figs. 2–4. The drawing is reproduced twice natural
size.
[219] Oldham and Morris (63) Pls. xxxiii. xxxv.
[220] Feistmantel (77) p. 87.
[221] Heer (76) Pl. xv. figs. 1–8.
[222] Nathorst (90) A. Pl. ii. fig. 3. Saporta (94) Pls. xxiii.-xxvi. Knowlton (98) p. 136.
[223] Lesquereux (78) Pl. v. fig. 12. See also Knowlton loc. cit.
[224] Zeiller (06) p. 141, Pls. xxxix. xli.
[225] Zeiller (00) p. 1077.
[226] Bennie and Kidston (88) Pl. vi. fig. 22.
[227] Goldenberg (55) Pl. i. fig. 3.
[228] Schimper (70) A. Pl. lvii. fig. 2.
[229] Halle (07).
[230] Goldenberg (55) Pl. i. fig. 2.
[231] Schimper (70) A. p. 10.
[232] Nathorst (08).
[233] Nathorst (022) p. 5, Pl. i. fig. 1.
[234] Fliche (03).
[235] Fliche (09).
[236] Scott (01).
[237] Rodway (95) A. p. 153.
Page 736
[238] A good example of an old Lepidodendron stem (L. aculeatum) is figured by
Zalessky (04) Pl. i. fig. 3.
[239] Seward and Ford (06) Pl. xxiii. fig. C.
[240] See Fischer (04).
[241] Bertrand, C. E. (91) p. 84: derived from παρά, by the side of, and ἴχνος, trace or
foot-print.
[242] Renault (96) A. Pls. xxxiii. xxxiv. p. 178. For a good section of another
Lepidodendron leaf, see Scott (08) p. 160, figs. 64, 65.
[243] Weiss, F. E. (07).
[244] For a fuller account of the parichnos, see Hill, T. G. (06) and other papers quoted
by F. E. Weiss (07).
[245] Barrois (04). See also Etheridge (80); Geikie (03) p. 1049.
[246] Binney (48).
[247] Darwin (03) vol. ii. pp. 217, 220.
[248] Solms-Laubach (92) Pl. ii. figs. 2, 4.
[249] Williamson (93) p. 10.
[250] Potonié (05) Lief, iii., p. 41.
[251] Stur (75) A. Heft ii. p. 277.
[252] Potonié (05) fig. 4.
[253] Seward and Leslie (08) Pl. x. figs. 1 and 2.
[254] Sternberg (26) A. Pl. xi. figs. 2–4; (02) p. 23.
[255] Corda (45) A. Pls. i.-iv.
[256] Zeiller (92) A.
[257] Kidston (93) p. 561, Pls. i. and ii.
[258] Seward (90).
[259] Williamson (93) Pl. iv. figs. 30–32.
[260] Binney (62).
[261] Binney (65); see also Binney (72).
[262] Williamson (72).
[263] Weiss, F. E. and Lomax (05).
[264] Binney (62).
[265] Carruthers (69) p. 179.
[266] Kidston (86) A. p. 151.
[267] Seward (06) p. 372.
[268] Hovelacque (92).
[269] Solms-Laubach (92) Pl. ii. fig. 6; Seward and Hill (00) Pl. iv. fig. 26. See p. 910 of
the latter paper for other references.
[270] Gwynne-Vaughan (08).
[271] Jeffrey (98). See also Tansley (08) p. 37.
Zalessky (04) Pl. i. fig. 3.
[239] Seward and Ford (06) Pl. xxiii. fig. C.
[240] See Fischer (04).
[241] Bertrand, C. E. (91) p. 84: derived from παρά, by the side of, and ἴχνος, trace or
foot-print.
[242] Renault (96) A. Pls. xxxiii. xxxiv. p. 178. For a good section of another
Lepidodendron leaf, see Scott (08) p. 160, figs. 64, 65.
[243] Weiss, F. E. (07).
[244] For a fuller account of the parichnos, see Hill, T. G. (06) and other papers quoted
by F. E. Weiss (07).
[245] Barrois (04). See also Etheridge (80); Geikie (03) p. 1049.
[246] Binney (48).
[247] Darwin (03) vol. ii. pp. 217, 220.
[248] Solms-Laubach (92) Pl. ii. figs. 2, 4.
[249] Williamson (93) p. 10.
[250] Potonié (05) Lief, iii., p. 41.
[251] Stur (75) A. Heft ii. p. 277.
[252] Potonié (05) fig. 4.
[253] Seward and Leslie (08) Pl. x. figs. 1 and 2.
[254] Sternberg (26) A. Pl. xi. figs. 2–4; (02) p. 23.
[255] Corda (45) A. Pls. i.-iv.
[256] Zeiller (92) A.
[257] Kidston (93) p. 561, Pls. i. and ii.
[258] Seward (90).
[259] Williamson (93) Pl. iv. figs. 30–32.
[260] Binney (62).
[261] Binney (65); see also Binney (72).
[262] Williamson (72).
[263] Weiss, F. E. and Lomax (05).
[264] Binney (62).
[265] Carruthers (69) p. 179.
[266] Kidston (86) A. p. 151.
[267] Seward (06) p. 372.
[268] Hovelacque (92).
[269] Solms-Laubach (92) Pl. ii. fig. 6; Seward and Hill (00) Pl. iv. fig. 26. See p. 910 of
the latter paper for other references.
[270] Gwynne-Vaughan (08).
[271] Jeffrey (98). See also Tansley (08) p. 37.
Page 737
[272] Seward (99) p. 144.
[273] Steinberg (26) A.
[274] Goeppert (52) A. p. 196. See also Kidston (01) p. 50.
[275] ibid. (52) A. p. 44. Pls. xxx. xxxi. Lief. i and ii.
[276] Balfour (72) A.
[277] Good examples are given by Schmalhausen (77) Pl. iii.
[278] Steinhauer (18) A. Pl. iv. fig. 5.
[279] Brongniart (49) A. p. 42.
[280] Goldenberg (55).
[281] Carruthers (732) p. 6.
[282] Feistmantel (75) A.
[283] Potonié (05) Lief. iii. 42–44.
[284] Artis (25) A. Pls. xvi. xxiii.
[285] Steinberg (38) A.
[286] Stur (75) A. Heft ii. p. 229.
[287] Lindley and Hutton (31) A. Pls. v. and vi.
[288] Kidston (85). In this important paper Dr Kidston gives a full account of the history
of our knowledge of Ulodendron.
[289] Steinhauer (18) A. p. 286, Pl. vii. fig. 1.
[290] Rhode (20) Pl. iii.
[291] Lindley and Hutton (31) A.
[292] Hooker (48), p. 427.
[293] Geinitz (55) A.
[294] Carruthers (70).
[295] Williamson (72).
[296] Thompson, D’Arcy (80).
[297] Kidston (85).
[298] Seward and Ford (06) Pl. xxiii. fig. C.
[299] Shattock (88).
[300] Watson (08).
[301] Watson (08) p. 10.
[302] Renier (08).
[303] Stur (75) A. Heft ii.
[304] Garden and Forest, vol. v., pp. 160–162, fig. 24 (April 6, 1902).
[305] Lindley and Hutton (35) A.
[306] Kidston (93) Pl. ii. fig. 6.
[307] ibid. (02) Pl. liii. fig. 2.
[273] Steinberg (26) A.
[274] Goeppert (52) A. p. 196. See also Kidston (01) p. 50.
[275] ibid. (52) A. p. 44. Pls. xxx. xxxi. Lief. i and ii.
[276] Balfour (72) A.
[277] Good examples are given by Schmalhausen (77) Pl. iii.
[278] Steinhauer (18) A. Pl. iv. fig. 5.
[279] Brongniart (49) A. p. 42.
[280] Goldenberg (55).
[281] Carruthers (732) p. 6.
[282] Feistmantel (75) A.
[283] Potonié (05) Lief. iii. 42–44.
[284] Artis (25) A. Pls. xvi. xxiii.
[285] Steinberg (38) A.
[286] Stur (75) A. Heft ii. p. 229.
[287] Lindley and Hutton (31) A. Pls. v. and vi.
[288] Kidston (85). In this important paper Dr Kidston gives a full account of the history
of our knowledge of Ulodendron.
[289] Steinhauer (18) A. p. 286, Pl. vii. fig. 1.
[290] Rhode (20) Pl. iii.
[291] Lindley and Hutton (31) A.
[292] Hooker (48), p. 427.
[293] Geinitz (55) A.
[294] Carruthers (70).
[295] Williamson (72).
[296] Thompson, D’Arcy (80).
[297] Kidston (85).
[298] Seward and Ford (06) Pl. xxiii. fig. C.
[299] Shattock (88).
[300] Watson (08).
[301] Watson (08) p. 10.
[302] Renier (08).
[303] Stur (75) A. Heft ii.
[304] Garden and Forest, vol. v., pp. 160–162, fig. 24 (April 6, 1902).
[305] Lindley and Hutton (35) A.
[306] Kidston (93) Pl. ii. fig. 6.
[307] ibid. (02) Pl. liii. fig. 2.
Page 738
[308] Williamson (832) A. Pl. 34.
[309] Feistmantel (75) A. p. 193, Pls. xxxiv.-xxxvii.
[310] Feistmantel loc. cit. Pl. xlvii.
[311] Grand’Eury (90) A.
[312] Dawes (48).
[313] Binney (72); see also Seward (99).
[314] Carruthers (732).
[315] Williamson (72).
[316] ibid. (93).
[317] Weiss, F. E. (03).
[318] Kidston (05).
[319] Renault (96) A. p. 175, Pls. xxxiii. xxxiv.
[320] For description of the leaf-anatomy, see pp. 98, 99.
[321] Renault (79) p. 249, Pl. x.
[322] Solms-Laubach (96) p. 18, Pl. x. figs. 7–11.
[323] They are regarded as identical by Fischer (04).
[324] Binney (72) Pl. xiii. fig. 1.
[325] Seward (99).
[326] As Miss Stokey (09) points out the production of parenchyma internal to the
cambium of L. fuliginosum is a feature shared by Isoetes. See also Scott and Hill (00), p.
424.
[327] Williamson (81) A. Pl. lii. p. 288. (Will. Coll. No. 379.)
[328] Binney (72).
[329] Cash and Lomax (90).
[330] Kidston (93) p. 547.
[331] Weiss, F. E. (03) p. 218.
[332] Scott, D. H. (063).
[333] Watson (07) p. 18.
[334] Seward (06) p. 378.
[335] Weiss, F. E. (02).
[336] Hick (93).
[337] Hick (932).
[338] See p. 240.
[339] Hick (93) Pl. xvi. fig. 1.
[340] Witham (31) A.
[341] Witham (33) A. Pls. xii. xiii.
[342] Lindley and Hutton (35) A. Pls. 98, 99.
[343] Brongniart (39) A.
[309] Feistmantel (75) A. p. 193, Pls. xxxiv.-xxxvii.
[310] Feistmantel loc. cit. Pl. xlvii.
[311] Grand’Eury (90) A.
[312] Dawes (48).
[313] Binney (72); see also Seward (99).
[314] Carruthers (732).
[315] Williamson (72).
[316] ibid. (93).
[317] Weiss, F. E. (03).
[318] Kidston (05).
[319] Renault (96) A. p. 175, Pls. xxxiii. xxxiv.
[320] For description of the leaf-anatomy, see pp. 98, 99.
[321] Renault (79) p. 249, Pl. x.
[322] Solms-Laubach (96) p. 18, Pl. x. figs. 7–11.
[323] They are regarded as identical by Fischer (04).
[324] Binney (72) Pl. xiii. fig. 1.
[325] Seward (99).
[326] As Miss Stokey (09) points out the production of parenchyma internal to the
cambium of L. fuliginosum is a feature shared by Isoetes. See also Scott and Hill (00), p.
424.
[327] Williamson (81) A. Pl. lii. p. 288. (Will. Coll. No. 379.)
[328] Binney (72).
[329] Cash and Lomax (90).
[330] Kidston (93) p. 547.
[331] Weiss, F. E. (03) p. 218.
[332] Scott, D. H. (063).
[333] Watson (07) p. 18.
[334] Seward (06) p. 378.
[335] Weiss, F. E. (02).
[336] Hick (93).
[337] Hick (932).
[338] See p. 240.
[339] Hick (93) Pl. xvi. fig. 1.
[340] Witham (31) A.
[341] Witham (33) A. Pls. xii. xiii.
[342] Lindley and Hutton (35) A. Pls. 98, 99.
[343] Brongniart (39) A.
Page 739
[344] Kidston (03) p. 822.
[345] Williamson (87).
[346] Kidston (03) p. 822; Watson (07).
[347] Bertrand, C. E. (91).
[348] Williamson (80) A.
[349] Williamson (93) Pl. i. fig. 3.
[350] Volume i. p. 89. For other references to these stems, see Seward and Hill (00) p.
918.
[351] Wünsch (67).
[352] Carruthers (692) p. 6.
[353] Williamson (80) A.; (93); (95).
[354] Wünsch loc. cit.
[355] Binney (71) p. 56.
[356] Carruthers (69).
[357] Seward and Hill (00).
[358] Williamson (96) p. 175.
[359] The term meristematic zone is used because some of the cells in this region are in
a state of active division, though the inner portion may consist of permanent tissue.
[360] Scott (00) p. 131; (08) p. 142.
[361] Seward and Hill (00) Pl. ii. fig. 14.
[362] Worsdell (95); Bernard (04).
[363] No. 52, 625.
[364] Seward and Hill (00) p. 922.
[365] Binney (71) p. 56, Pl. xi. figs. 2a-2c.
[366] Williamson (72) p. 298, pl. xlv. fig. 35.
[367] Carruthers (72).
[368] Williamson (93) p. 30.
[369] Goldenberg (55) p. 12.
[370] See also Kidston (94), (86) A. p. 160; Potonié (05) Lief. iii. 50.
[371] Stur (75) A. ii. p. 330, fig. 34.
[372] Hannig (98).
[373] Young and Kidston (88) A.
[374] Potonié (012) fig. 72, p. 117.
[375] Stur (75) II. A. Pl. xxxvi. fig. 9.
[376] See Chap. xvii.
[377] Williamson (72) Pl. xliv. p. 294: (93) (932).
[378] Kidston (01) p. 60. See also Scott (00) p. 170, figs. 67, 68.
[379] Williamson (93), Pl. viii. figs. 51, 52. See also figs. 67–69 given by Scott (00).
[345] Williamson (87).
[346] Kidston (03) p. 822; Watson (07).
[347] Bertrand, C. E. (91).
[348] Williamson (80) A.
[349] Williamson (93) Pl. i. fig. 3.
[350] Volume i. p. 89. For other references to these stems, see Seward and Hill (00) p.
918.
[351] Wünsch (67).
[352] Carruthers (692) p. 6.
[353] Williamson (80) A.; (93); (95).
[354] Wünsch loc. cit.
[355] Binney (71) p. 56.
[356] Carruthers (69).
[357] Seward and Hill (00).
[358] Williamson (96) p. 175.
[359] The term meristematic zone is used because some of the cells in this region are in
a state of active division, though the inner portion may consist of permanent tissue.
[360] Scott (00) p. 131; (08) p. 142.
[361] Seward and Hill (00) Pl. ii. fig. 14.
[362] Worsdell (95); Bernard (04).
[363] No. 52, 625.
[364] Seward and Hill (00) p. 922.
[365] Binney (71) p. 56, Pl. xi. figs. 2a-2c.
[366] Williamson (72) p. 298, pl. xlv. fig. 35.
[367] Carruthers (72).
[368] Williamson (93) p. 30.
[369] Goldenberg (55) p. 12.
[370] See also Kidston (94), (86) A. p. 160; Potonié (05) Lief. iii. 50.
[371] Stur (75) A. ii. p. 330, fig. 34.
[372] Hannig (98).
[373] Young and Kidston (88) A.
[374] Potonié (012) fig. 72, p. 117.
[375] Stur (75) II. A. Pl. xxxvi. fig. 9.
[376] See Chap. xvii.
[377] Williamson (72) Pl. xliv. p. 294: (93) (932).
[378] Kidston (01) p. 60. See also Scott (00) p. 170, figs. 67, 68.
[379] Williamson (93), Pl. viii. figs. 51, 52. See also figs. 67–69 given by Scott (00).
Page 740
[380] Scott (00) p. 173.
[381] Scott [(08) p. 187] suggests that the projection may have formed a passage for the
admission of the microspores, or of the spermatozoids which they produced.
[382] Bennie and Kidston (88) Pl. vi. figs. 20, a–s.
[383] Gordon (08).
[384] Williamson (72).
[385] Carruthers (692).
[386] Zeiller (95). See also White (08) p. 447.
[387] Arber (05) Pl. i. fig. 2.
[388] Seward and Leslie (08).
[389] Zeiller (98).
[390] Renault (90).
[391] Seward (073).
[392] Nathorst (07); Bather (07); (08).
[393] Seward (972) A. p. 326, Pl. xxiii.
[394] Carruthers (722).
[395] Unger and Richter (56).
[396] Dawson (71) A. Pl. viii. See also Smith and White (05).
[397] M’Coy (74). See also Feistmantel (90) A.
[398] Kidston (86) A. p. 231.
[399] Krasser (00) Pl. ii. fig. 1.
[400] Nathorst (94) A. Pl. ii. fig. 8.
[401] Szajnocha (91) p. 203.
[402] See Etheridge (90); David and Pittman (93).
[403] White (08).
[404] Brongniart (28) A. p. 87.
[405] Parkinson (11) A. Pl. ix. fig. 1, p. 428.
[406] Carruthers (692).
[407] Brongniart (22) A. Pl. ii. fig. 4.
[408] Bower (08) p. 305.
[409] Seward (90); Potonié (932).
[410] Brongniart (37) Pl. xxiv.
[411] Morris (40) Pl. xxxviii. fig. 10.
[412] Williamson (93) Pl. vi. fig. 26, A.
[413] Kidston (01) p. 62.
[414] Renault and Zeiller (88) A. Pl. lxi. fig. 4.
[415] Hooker (482).
[381] Scott [(08) p. 187] suggests that the projection may have formed a passage for the
admission of the microspores, or of the spermatozoids which they produced.
[382] Bennie and Kidston (88) Pl. vi. figs. 20, a–s.
[383] Gordon (08).
[384] Williamson (72).
[385] Carruthers (692).
[386] Zeiller (95). See also White (08) p. 447.
[387] Arber (05) Pl. i. fig. 2.
[388] Seward and Leslie (08).
[389] Zeiller (98).
[390] Renault (90).
[391] Seward (073).
[392] Nathorst (07); Bather (07); (08).
[393] Seward (972) A. p. 326, Pl. xxiii.
[394] Carruthers (722).
[395] Unger and Richter (56).
[396] Dawson (71) A. Pl. viii. See also Smith and White (05).
[397] M’Coy (74). See also Feistmantel (90) A.
[398] Kidston (86) A. p. 231.
[399] Krasser (00) Pl. ii. fig. 1.
[400] Nathorst (94) A. Pl. ii. fig. 8.
[401] Szajnocha (91) p. 203.
[402] See Etheridge (90); David and Pittman (93).
[403] White (08).
[404] Brongniart (28) A. p. 87.
[405] Parkinson (11) A. Pl. ix. fig. 1, p. 428.
[406] Carruthers (692).
[407] Brongniart (22) A. Pl. ii. fig. 4.
[408] Bower (08) p. 305.
[409] Seward (90); Potonié (932).
[410] Brongniart (37) Pl. xxiv.
[411] Morris (40) Pl. xxxviii. fig. 10.
[412] Williamson (93) Pl. vi. fig. 26, A.
[413] Kidston (01) p. 62.
[414] Renault and Zeiller (88) A. Pl. lxi. fig. 4.
[415] Hooker (482).
Page 741
[416] Binney (71).
[417] Williamson (93) p. 26.
[418] Maslen (99).
[419] Lindley and Hutton (37) A. Pl. 163.
[420] For a detailed account of this type, see Maslen (99).
[421] Williamson (93) p. 28.
[422] Binney (71).
[423] Binney (71) Pl. viii. figs. 2, 4.
[424] Maslen (99) Pl. xxxvi fig. 11.
[425] Brown, R. (51).
[426] Brongniart (68).
[427] Schimper (70) A. p. 67, Pl. lxii. figs. 13–29.
[428] Bower (93).
[429] Bower (94) Pl. xlviii. fig. 93.
[430] Zeiller (09).
[431] Zalessky has recently (08) described a large species of cone, Lepidostrobus
Bertrandi, 5 cm. in diameter.
[432] Morris (40).
[433] Balfour (57).
[434] Kidston and Bennie (88).
[435] Reinsch (81) A.
[436] Scott, R. (06).
[437] Maslen (99) p. 373; Scott, R. (06) p. 117.
[438] Campbell (05) p. 414.
[439] Williamson (78) A. p. 340, Pl. xxii. See also the drawings in Williamson’s later
papers quoted in the synonymy.
[440] Williamson (932).
[441] Scott, D. H. (98).
[442] Berridge (05).
[443] Lang (08).
[444] Lang (08) p. 364.
[445] Williamson (78) A. Pl. xxii. fig. 53.
[446] Lang (08) p. 367. Since this was written a paper has been published by Mr Watson
on a new type of Lycopodiaceous cone from the Lower Coal-Measures (Mesostrobus): in
an appendix he criticises Dr Lang’s views in regard to Spencerites. [Watson, Annals of
Botany, Vol. xxiii. p. 379, 1909.]
[447] Seward and Ford (06) p. 395.
[448] Artis (25) A. Pl. xv.
[449] Rhode (20).
[417] Williamson (93) p. 26.
[418] Maslen (99).
[419] Lindley and Hutton (37) A. Pl. 163.
[420] For a detailed account of this type, see Maslen (99).
[421] Williamson (93) p. 28.
[422] Binney (71).
[423] Binney (71) Pl. viii. figs. 2, 4.
[424] Maslen (99) Pl. xxxvi fig. 11.
[425] Brown, R. (51).
[426] Brongniart (68).
[427] Schimper (70) A. p. 67, Pl. lxii. figs. 13–29.
[428] Bower (93).
[429] Bower (94) Pl. xlviii. fig. 93.
[430] Zeiller (09).
[431] Zalessky has recently (08) described a large species of cone, Lepidostrobus
Bertrandi, 5 cm. in diameter.
[432] Morris (40).
[433] Balfour (57).
[434] Kidston and Bennie (88).
[435] Reinsch (81) A.
[436] Scott, R. (06).
[437] Maslen (99) p. 373; Scott, R. (06) p. 117.
[438] Campbell (05) p. 414.
[439] Williamson (78) A. p. 340, Pl. xxii. See also the drawings in Williamson’s later
papers quoted in the synonymy.
[440] Williamson (932).
[441] Scott, D. H. (98).
[442] Berridge (05).
[443] Lang (08).
[444] Lang (08) p. 364.
[445] Williamson (78) A. Pl. xxii. fig. 53.
[446] Lang (08) p. 367. Since this was written a paper has been published by Mr Watson
on a new type of Lycopodiaceous cone from the Lower Coal-Measures (Mesostrobus): in
an appendix he criticises Dr Lang’s views in regard to Spencerites. [Watson, Annals of
Botany, Vol. xxiii. p. 379, 1909.]
[447] Seward and Ford (06) p. 395.
[448] Artis (25) A. Pl. xv.
[449] Rhode (20).
Page 742
[450] Brongniart (22) A. Pl. xii. fig. 4.
[451] For generic names wholly or in part synonymous with Sigillaria, see White (99) p.
230.
[452] Kidston (86) A. p. 186.
[453] Brongniart (37) Pl. cl. fig. 1.
[454] Brongniart (22) A. Pl. xii. fig. 3.
[455] Sternberg (23) A.
[456] Goldenberg (55).
[457] Zeiller (88) A. (S. elegans).
[458] Goldenberg (55).
[459] Renault (96) A. Pl. xxxv.
[460] Stur (75) ii. A. Pl. xlii.
[461] For an account of the various external features made use of in the classification of
Sigillarias, see Koehne (04).
[462] Grand’Eury (90) A.
[463] Germar (53).
[464] Cf. Lepidodendron Zeilleri, Zalessky (04) Pl. iv. fig. 1.
[465] Lesquereux (79) A. Pl. lxiv.
[466] Zeiller (88) A. Pl. lxxi.
[467] Kidston (01) p. 46.
[468] Kidston (85).
[469] White, D. (072).
[470] Weiss, C. E. (88).
[471] Zeiller (89).
[472] Kidston (01) p. 94.
[473] Seward (902).
[474] Weiss, C. E. (89).
[475] Grand’Eury (90) A.
[476] Kidston (97) p. 46.
[477] Grand’Eury (90) A. Pl. xiii. fig. 8.
[478] Renault and Roche (97).
[479] Coward (07); Renault (96) A.
[480] Grand’Eury (90) a. Pl. iii.
[481] Cf. Prof. Yapp’s account (08) of Fen vegetation.
[482] Zeiller (88) A. Pl. lxxxv.
[483] Brongniart (28) A. p. 63.
[484] Brongniart (39) A.; (49) A. p. 55.
[485] Williamson (83).
[451] For generic names wholly or in part synonymous with Sigillaria, see White (99) p.
230.
[452] Kidston (86) A. p. 186.
[453] Brongniart (37) Pl. cl. fig. 1.
[454] Brongniart (22) A. Pl. xii. fig. 3.
[455] Sternberg (23) A.
[456] Goldenberg (55).
[457] Zeiller (88) A. (S. elegans).
[458] Goldenberg (55).
[459] Renault (96) A. Pl. xxxv.
[460] Stur (75) ii. A. Pl. xlii.
[461] For an account of the various external features made use of in the classification of
Sigillarias, see Koehne (04).
[462] Grand’Eury (90) A.
[463] Germar (53).
[464] Cf. Lepidodendron Zeilleri, Zalessky (04) Pl. iv. fig. 1.
[465] Lesquereux (79) A. Pl. lxiv.
[466] Zeiller (88) A. Pl. lxxi.
[467] Kidston (01) p. 46.
[468] Kidston (85).
[469] White, D. (072).
[470] Weiss, C. E. (88).
[471] Zeiller (89).
[472] Kidston (01) p. 94.
[473] Seward (902).
[474] Weiss, C. E. (89).
[475] Grand’Eury (90) A.
[476] Kidston (97) p. 46.
[477] Grand’Eury (90) A. Pl. xiii. fig. 8.
[478] Renault and Roche (97).
[479] Coward (07); Renault (96) A.
[480] Grand’Eury (90) a. Pl. iii.
[481] Cf. Prof. Yapp’s account (08) of Fen vegetation.
[482] Zeiller (88) A. Pl. lxxxv.
[483] Brongniart (28) A. p. 63.
[484] Brongniart (39) A.; (49) A. p. 55.
[485] Williamson (83).
Page 743
[486] Williamson (72) p. 228.
[487] Renault (79).
[488] Goldenberg (55) p. 24.
[489] Schimper (70) A. p. 105.
[490] Zeiller (84).
[491] Zeiller (88) A.
[492] Kidston (97).
[493] Grand’Eury (90) A. Vol. ii.
[494] Kidston (97).
[495] Renault (96) A.
[496] Kidston (85).
[497] Lindley and Hutton (31) A. Pl. vi.
[498] Thompson (80).
[499] Kidston (85) Pl. vi. fig. 10.
[500] Kidston (892) p. 61; Pl. vi. fig. 1.
[501] Zeiller (88) A. p. 483, Pls. lxxiii. lxxiv.
[502] Zeiller (06) Pl. xlii.
[503] Kidston (072).
[504] Renault (96) A. Pl. xxxvii. fig. 3.
[505] Renault (79) Pls. xii. xiii. p. 270; (96) A. p. 245.
[506] Scott, D. H. (042).
[507] Scott (08) p 230, fig. 95.
[508] Kidston (072).
[509] Arber and Thomas (08).
[510] Goldenberg (55); Kidston (97).
[511] Zeiller (88) A. Pl. xc. 1, p. 598.
[512] Zeiller (84); (88) A. Pl. lxxxix.
[513] Kidston (97) Pls. i. ii. p. 50.
[514] Goldenberg (55).
[515] Kidston (05) Pl. iii. figs. 23, 25, 26, 27.
[516] Zeiller (06) p. 160.
[517] Brongniart (39); Renault (96) A.
[518] Zeiller (88) A. p. 586; Kidston (05) p. 534.
[519] Renault and Grand’Eury (75); Renault (96) A.
[520] Germar (44) A.
[521] Scott (08) p. 219.
[522] Solms-Laubach (91) A. p. 253.
[487] Renault (79).
[488] Goldenberg (55) p. 24.
[489] Schimper (70) A. p. 105.
[490] Zeiller (84).
[491] Zeiller (88) A.
[492] Kidston (97).
[493] Grand’Eury (90) A. Vol. ii.
[494] Kidston (97).
[495] Renault (96) A.
[496] Kidston (85).
[497] Lindley and Hutton (31) A. Pl. vi.
[498] Thompson (80).
[499] Kidston (85) Pl. vi. fig. 10.
[500] Kidston (892) p. 61; Pl. vi. fig. 1.
[501] Zeiller (88) A. p. 483, Pls. lxxiii. lxxiv.
[502] Zeiller (06) Pl. xlii.
[503] Kidston (072).
[504] Renault (96) A. Pl. xxxvii. fig. 3.
[505] Renault (79) Pls. xii. xiii. p. 270; (96) A. p. 245.
[506] Scott, D. H. (042).
[507] Scott (08) p 230, fig. 95.
[508] Kidston (072).
[509] Arber and Thomas (08).
[510] Goldenberg (55); Kidston (97).
[511] Zeiller (88) A. Pl. xc. 1, p. 598.
[512] Zeiller (84); (88) A. Pl. lxxxix.
[513] Kidston (97) Pls. i. ii. p. 50.
[514] Goldenberg (55).
[515] Kidston (05) Pl. iii. figs. 23, 25, 26, 27.
[516] Zeiller (06) p. 160.
[517] Brongniart (39); Renault (96) A.
[518] Zeiller (88) A. p. 586; Kidston (05) p. 534.
[519] Renault and Grand’Eury (75); Renault (96) A.
[520] Germar (44) A.
[521] Scott (08) p. 219.
[522] Solms-Laubach (91) A. p. 253.
Page 744
[523] Renault and Grand’Eury (75) Pl. i. fig. 5.
[524] Coward (07).
[525] Renault (96) A. p. 237, Pl. xxxviii. figs. 1–4.
[526] Kidston (05).
[527] Brongniart (28) A. Pls. cxlvi. clv. clviii.
[528] Bertrand (99).
[529] Scott (08) p. 227, fig. 93.
[530] Kidston (072).
[531] Arber and Thomas (07).
[532] Williamson (72).
[533] Scott (08) p. 227.
[534] Mettenius (60).
[535] e.g. L. Wünschianum (fig. 181, B, lt).
[536] Kidston (05) p. 547.
[537] Scott, D. H. (02).
[538] For fuller synonymy, see Kidston (86) A. p. 179; and Zeiller (06) p 160; Koehne
(04) p. 62.
[539] Renault (96) A. Pl. xxxv.; Zeiller (06) Pl. xlii.
[540] Grand’Eury (90) A.
[541] Zeiller (06) Pl. xlii.
[542] Renault (96) A. Pls. xxxvii. xli.
[543] Grand’Eury (90) A. Pl. xi.
[544] Zeiller (06) p. 176.
[545] Goldenberg (55) Pl. xii.
[546] Renault (96) A. Pl. xxxix.
[547] Zeiller (92) A.; (06).
[548] Potonié (96) A.
[549] Fontaine and White (80).
[550] Kidston (94) p. 252.
[551] Seward (972) A.
[552] White (08) p. 450, Pl. v. fig. 12.
[553] Potonié (012).
[554] Goeppert (64) A.
[555] Goeppert, loc. cit.
[556] Gresley (89) Pl. ii.
[557] Steinhauer (18) A.
[558] Logan (42).
[524] Coward (07).
[525] Renault (96) A. p. 237, Pl. xxxviii. figs. 1–4.
[526] Kidston (05).
[527] Brongniart (28) A. Pls. cxlvi. clv. clviii.
[528] Bertrand (99).
[529] Scott (08) p. 227, fig. 93.
[530] Kidston (072).
[531] Arber and Thomas (07).
[532] Williamson (72).
[533] Scott (08) p. 227.
[534] Mettenius (60).
[535] e.g. L. Wünschianum (fig. 181, B, lt).
[536] Kidston (05) p. 547.
[537] Scott, D. H. (02).
[538] For fuller synonymy, see Kidston (86) A. p. 179; and Zeiller (06) p 160; Koehne
(04) p. 62.
[539] Renault (96) A. Pl. xxxv.; Zeiller (06) Pl. xlii.
[540] Grand’Eury (90) A.
[541] Zeiller (06) Pl. xlii.
[542] Renault (96) A. Pls. xxxvii. xli.
[543] Grand’Eury (90) A. Pl. xi.
[544] Zeiller (06) p. 176.
[545] Goldenberg (55) Pl. xii.
[546] Renault (96) A. Pl. xxxix.
[547] Zeiller (92) A.; (06).
[548] Potonié (96) A.
[549] Fontaine and White (80).
[550] Kidston (94) p. 252.
[551] Seward (972) A.
[552] White (08) p. 450, Pl. v. fig. 12.
[553] Potonié (012).
[554] Goeppert (64) A.
[555] Goeppert, loc. cit.
[556] Gresley (89) Pl. ii.
[557] Steinhauer (18) A.
[558] Logan (42).
Page 745
[559] Potonié (933).
[560] Williamson (87) A.
[561] A similar example, now in the Bergakademie of Berlin, has been described by
Potonié (90) A.; see also a note on the German specimen by Seward (91).
[562] Martin (09) A. Pl. xii.
[563] Artis (25) A.
[564] Lindley and Hutton (38) A. Pl. clxvi.
[565] For a fuller synonymy, see Kidston (03) p. 757.
[566] Goldenberg (55) p. 6.
[567] Binney (44) p. 165.
[568] Brongniart (22) A. p. 228.
[569] ibid. (49) A. p. 456.
[570] Artis (25) A. Pl. x.
[571] Lindley and Hutton (31) A. Pl. xxxi.
[572] Goldenberg (55).
[573] Logan (42) p. 492.
[574] Binney (44); (46).
[575] Bowman (41).
[576] Brown (45); (46); (47); (49). See also Dawson (66).
[577] Hawkshaw (42).
[578] Binney (46) p. 393.
[579] Brown (49). This figure is reproduced by Williamson (87) A. p. 16.
[580] Williamson (87) A. p. 3. Solms-Laubach (91) A. p. 284.
[581] Mellor and Leslie (06).
[582] Goeppert (64) A. p. 197, Pls. 34–36.
[583] Renault (81).
[584] Grand’Eury (90) A.
[585] Solms-Laubach (94).
[586] Grand’Eury (77) A. p. 171.
[560] Williamson (87) A.
[561] A similar example, now in the Bergakademie of Berlin, has been described by
Potonié (90) A.; see also a note on the German specimen by Seward (91).
[562] Martin (09) A. Pl. xii.
[563] Artis (25) A.
[564] Lindley and Hutton (38) A. Pl. clxvi.
[565] For a fuller synonymy, see Kidston (03) p. 757.
[566] Goldenberg (55) p. 6.
[567] Binney (44) p. 165.
[568] Brongniart (22) A. p. 228.
[569] ibid. (49) A. p. 456.
[570] Artis (25) A. Pl. x.
[571] Lindley and Hutton (31) A. Pl. xxxi.
[572] Goldenberg (55).
[573] Logan (42) p. 492.
[574] Binney (44); (46).
[575] Bowman (41).
[576] Brown (45); (46); (47); (49). See also Dawson (66).
[577] Hawkshaw (42).
[578] Binney (46) p. 393.
[579] Brown (49). This figure is reproduced by Williamson (87) A. p. 16.
[580] Williamson (87) A. p. 3. Solms-Laubach (91) A. p. 284.
[581] Mellor and Leslie (06).
[582] Goeppert (64) A. p. 197, Pls. 34–36.
[583] Renault (81).
[584] Grand’Eury (90) A.
[585] Solms-Laubach (94).
[586] Grand’Eury (77) A. p. 171.
Page 746
[587] For figures see Grand’Eury (87) A.; (90) A.
[588] Kidston (02) Pl. li. fig. 4.
[589] British Museum, No. 870 F.
[590] Grand’Eury (90) A.
[591] Solms-Laubach (94).
[592] Williamson (92).
[593] Thomas, E. N. (05) p. 187.
[594] Williamson (87) A.
[595] Solms-Laubach (92).
[596] Renault (96) A. Pl. xl. fig. 5.
[597] Weiss, F. E. (08).
[598] Williamson (89) A.
[599] Renault (96) A.
[600] Williamson (87) A. Pl. iv. fig. 20.
[601] Weiss, F. E. (02).
[602] Hooker (482) Pls. i. ii. The sections of Stigmaria figured by Hooker are in the
British Museum (V. 8754).
[603] Williamson (87) A. Pl. xii.
[604] Solms-Laubach (91) A.
[605] Weiss, F. E. (02).
[606] Weiss, F. E. (04).
[607] Goeppert (41) Pl. x. Lief. i. ii.; Williamson (87) A. Pl. xiii. fig. 78; Eichwald (60)
Pl. xv.; Kidston (94) p. 254.
[608] Goldenberg (55) Pl. vi. figs. 1–4.
[609] Nathorst (94) A. Pl. xvi. fig. 9.
[610] Watson (08).
[611] Zeiller (88) A. Pl. lxxvii. fig. 1.
[612] Cf. Lindley and Hutton (35) A. Pls. 80, 81.
[613] Kidston (86) A. p. 175.
[614] ibid. (864) p. 65.
[615] Haughton (59).
[616] Weiss, C. E. (84) Pl. vi. figs. 6, 7.
[617] Lindley and Hutton (35) A. Pls. 80, 81. For synonymy, see Kidston (93) p. 344.
[618] Zeiller (86) Pl. IX. figs. 1–3.
[619] No. 52524.
[588] Kidston (02) Pl. li. fig. 4.
[589] British Museum, No. 870 F.
[590] Grand’Eury (90) A.
[591] Solms-Laubach (94).
[592] Williamson (92).
[593] Thomas, E. N. (05) p. 187.
[594] Williamson (87) A.
[595] Solms-Laubach (92).
[596] Renault (96) A. Pl. xl. fig. 5.
[597] Weiss, F. E. (08).
[598] Williamson (89) A.
[599] Renault (96) A.
[600] Williamson (87) A. Pl. iv. fig. 20.
[601] Weiss, F. E. (02).
[602] Hooker (482) Pls. i. ii. The sections of Stigmaria figured by Hooker are in the
British Museum (V. 8754).
[603] Williamson (87) A. Pl. xii.
[604] Solms-Laubach (91) A.
[605] Weiss, F. E. (02).
[606] Weiss, F. E. (04).
[607] Goeppert (41) Pl. x. Lief. i. ii.; Williamson (87) A. Pl. xiii. fig. 78; Eichwald (60)
Pl. xv.; Kidston (94) p. 254.
[608] Goldenberg (55) Pl. vi. figs. 1–4.
[609] Nathorst (94) A. Pl. xvi. fig. 9.
[610] Watson (08).
[611] Zeiller (88) A. Pl. lxxvii. fig. 1.
[612] Cf. Lindley and Hutton (35) A. Pls. 80, 81.
[613] Kidston (86) A. p. 175.
[614] ibid. (864) p. 65.
[615] Haughton (59).
[616] Weiss, C. E. (84) Pl. vi. figs. 6, 7.
[617] Lindley and Hutton (35) A. Pls. 80, 81. For synonymy, see Kidston (93) p. 344.
[618] Zeiller (86) Pl. IX. figs. 1–3.
[619] No. 52524.
Page 747
[620] Nathorst (02) Pl. x. figs. 4, 5.
[621] Weiss, F. E. (08).
[622] Schimper (70) A. p. 71.
[623] Heer (71) Pl. vi. fig. 11; Pl. ix. fig. 1.
[624] Nathorst (94) A. p. 67, Pl. xv. figs. 14, 15.
[625] Schmalhausen (77) p. 281, Pl. i. fig. 5.
[626] Kidston (892) Pl. iv. figs. 2–4, p. 65.
[627] Weiss and Sterzel (93) p. 56.
[628] Kidston (03) p. 823.
[629] Schmalhausen (77) p. 290, Pl. i. figs. 7–12.
[630] Dawson (71) A. Pl. viii.
[631] Weiss, C. E. (84) Pl. vii.
[632] Potonié (012) figs. 25–27.
[633] Nathorst (02) p. 35.
[634] Seward (03) Pl. xi. figs. 1–6, p. 87; Arber (05) p. 166.
[635] Seward (09).
[636] Feistmantel (90) A.
[637] Zeiller (802) A.
[638] Trautschold and Auerbach (60) Pl. iii.
[639] Zeiller (82) A.; (86).
[640] Nathorst (94) A. Pls. x. xi.
[641] Volume i. p. 134.
[642] Williamson (89) A. p. 197.
[643] I am indebted to Mr Lomax for photographs of his specimens. For former
references to Mr Lomax’s discovery, see Kidston (05); Weiss, F. E. (08); Scott D. H. (08)
p. 200.
[644] Williamson (89) A.
[645] Weiss, F. E. (08).
[646] Nathorst (94) A. p. 42.
[647] Williamson (80) A. p. 500, Pl. xv. 8.
[648] Watson (082) p. 12.
[649] Nathorst (94) A. p. 42, Pl. xii. figs. 8–10.
[650] Kidston (03) p. 797.
[651] White (98); (99) p. 218, Pls. lxv.-lxviii.
[652] Kidston (02) pp. 358, 359.
[653] Tansley and Chick (01) p. 36.
[654] Kidston (05) p. 547.
[655] Renault (96) A.
[621] Weiss, F. E. (08).
[622] Schimper (70) A. p. 71.
[623] Heer (71) Pl. vi. fig. 11; Pl. ix. fig. 1.
[624] Nathorst (94) A. p. 67, Pl. xv. figs. 14, 15.
[625] Schmalhausen (77) p. 281, Pl. i. fig. 5.
[626] Kidston (892) Pl. iv. figs. 2–4, p. 65.
[627] Weiss and Sterzel (93) p. 56.
[628] Kidston (03) p. 823.
[629] Schmalhausen (77) p. 290, Pl. i. figs. 7–12.
[630] Dawson (71) A. Pl. viii.
[631] Weiss, C. E. (84) Pl. vii.
[632] Potonié (012) figs. 25–27.
[633] Nathorst (02) p. 35.
[634] Seward (03) Pl. xi. figs. 1–6, p. 87; Arber (05) p. 166.
[635] Seward (09).
[636] Feistmantel (90) A.
[637] Zeiller (802) A.
[638] Trautschold and Auerbach (60) Pl. iii.
[639] Zeiller (82) A.; (86).
[640] Nathorst (94) A. Pls. x. xi.
[641] Volume i. p. 134.
[642] Williamson (89) A. p. 197.
[643] I am indebted to Mr Lomax for photographs of his specimens. For former
references to Mr Lomax’s discovery, see Kidston (05); Weiss, F. E. (08); Scott D. H. (08)
p. 200.
[644] Williamson (89) A.
[645] Weiss, F. E. (08).
[646] Nathorst (94) A. p. 42.
[647] Williamson (80) A. p. 500, Pl. xv. 8.
[648] Watson (082) p. 12.
[649] Nathorst (94) A. p. 42, Pl. xii. figs. 8–10.
[650] Kidston (03) p. 797.
[651] White (98); (99) p. 218, Pls. lxv.-lxviii.
[652] Kidston (02) pp. 358, 359.
[653] Tansley and Chick (01) p. 36.
[654] Kidston (05) p. 547.
[655] Renault (96) A.
Page 748
[656] Weiss, F. E. (08).
[657] Browne (09) p. 25.
[658] Scott (02) uses the terms old and new wood in discussing the evolutionary
sequence in plant steles.
[659] White (07).
[660] Bower (08) p. 305.
[661] Browne (09) p. 37.
[662] Williamson (77) and (80) A.
[663] Brongniart (28) A. p. 87.
[664] Carruthers (723).
[665] Wild and Lomax (00).
[666] Scott (01).
[667] Letter from D. H. Scott (March 30, 1908).
[668] Scott (01) 314.
[669] Seward and Ford (06).
[670] For a contrary opinion, see Scott (09) p. 656.
[671] Bertrand, E. (94).
[672] Benson (08).
[673] Watson (082) p. 12.
[674] Ward (04).
[675] Tansley (08) p. 3. Cf. Braun (75) p. 267.
[676] Chodat (08).
[677] Hudson (92) p. 29.
[678] Hardy, Return of the Native, ii. p. 153.
[679] Bower (08).
[680] Zeiller (06) p. 8.
[681] Engler (09).
[682] Bower (00).
[683] For an account of the mechanism of spore-dispersal, see Goebel (05) p. 587;
Atkinson (94); Leclerc du Sablon (85); and Bower (00).
[684] For a fuller account of recent ferns, see Engler and Prantl (02), Christ (97), Hooker
and Baker (68), and Bower (00) (08).
[685] Prantl (81) Pl. vii. fig. 104, C; Zeiller (97) p. 215, figs. 7–10.
[686] Underwood (07), p. 243, has adopted Bernhardi’s genus Dicranopteris in place of
Mertensia on the ground that the latter was used as early as 1793 for a Boraginaceous
plant.
[687] Goebel (05) p. 318.
[688] Baker (88).
[689] Diels, in Engler and Prantl (02) pp. 343, 344.
[657] Browne (09) p. 25.
[658] Scott (02) uses the terms old and new wood in discussing the evolutionary
sequence in plant steles.
[659] White (07).
[660] Bower (08) p. 305.
[661] Browne (09) p. 37.
[662] Williamson (77) and (80) A.
[663] Brongniart (28) A. p. 87.
[664] Carruthers (723).
[665] Wild and Lomax (00).
[666] Scott (01).
[667] Letter from D. H. Scott (March 30, 1908).
[668] Scott (01) 314.
[669] Seward and Ford (06).
[670] For a contrary opinion, see Scott (09) p. 656.
[671] Bertrand, E. (94).
[672] Benson (08).
[673] Watson (082) p. 12.
[674] Ward (04).
[675] Tansley (08) p. 3. Cf. Braun (75) p. 267.
[676] Chodat (08).
[677] Hudson (92) p. 29.
[678] Hardy, Return of the Native, ii. p. 153.
[679] Bower (08).
[680] Zeiller (06) p. 8.
[681] Engler (09).
[682] Bower (00).
[683] For an account of the mechanism of spore-dispersal, see Goebel (05) p. 587;
Atkinson (94); Leclerc du Sablon (85); and Bower (00).
[684] For a fuller account of recent ferns, see Engler and Prantl (02), Christ (97), Hooker
and Baker (68), and Bower (00) (08).
[685] Prantl (81) Pl. vii. fig. 104, C; Zeiller (97) p. 215, figs. 7–10.
[686] Underwood (07), p. 243, has adopted Bernhardi’s genus Dicranopteris in place of
Mertensia on the ground that the latter was used as early as 1793 for a Boraginaceous
plant.
[687] Goebel (05) p. 318.
[688] Baker (88).
[689] Diels, in Engler and Prantl (02) pp. 343, 344.
Page 749
[690] Compton (09).
[691] Copeland (08) p. 344.
[692] Bower (00) p. 47; Gwynne-Vaughan (01).
[693] Christ (04).
[694] Scott, J. (74); Hannig (98).
[695] Challenger Reports (85) p. 827. (Narrative, Pl. ii.)
[696] Bower (00) p. 68.
[697] Diels (02) p. 117.
[698] Seward (92) p. 45.
[699] Bower (00) p. 80.
[700] Prof. Bower informs me that he is now at work on Plagiogyria and other
Polypodiaceae.
[701] Kny (75); Ford (02); Goebel (91).
[702] Seward and Dale (01).
[703] Armour (07).
[704] Diels (02) fig. 98, p. 188.
[705] Giesenhagen (92) p. 179, fig. 3.
[706] Bäsecke (08).
[707] Boodle (00).
[708] Yapp (02).
[709] Darwin (03) ii. p. 381.
[710] Reinecke (97).
[711] Karsten (95); Christ (96); Bommer (03).
[712] Goebel (05) p. 347.
[713] A striking example of these so-called Aphlebiae of Hemitelia may be seen at the
Royal Gardens, Kew.
[714] Luerssen, in Rabenhorst (89) A. p. 483, fig. 164.
[715] Goebel (01) Pl. xiii.
[716] Spruce (08) ii. p. 232.
[717] Boodle (04).
[718] Goebel (05); Baker (67).
[719] Seward and Gowan (00).
[720] Hooker (59).
[721] Thiselton-Dyer (05).
[722] Baker (68) p. 305.
[723] Bower (08) p. 18.
[724] Treub (88) A.; Ernst (08).
[725] Campbell (07).
[691] Copeland (08) p. 344.
[692] Bower (00) p. 47; Gwynne-Vaughan (01).
[693] Christ (04).
[694] Scott, J. (74); Hannig (98).
[695] Challenger Reports (85) p. 827. (Narrative, Pl. ii.)
[696] Bower (00) p. 68.
[697] Diels (02) p. 117.
[698] Seward (92) p. 45.
[699] Bower (00) p. 80.
[700] Prof. Bower informs me that he is now at work on Plagiogyria and other
Polypodiaceae.
[701] Kny (75); Ford (02); Goebel (91).
[702] Seward and Dale (01).
[703] Armour (07).
[704] Diels (02) fig. 98, p. 188.
[705] Giesenhagen (92) p. 179, fig. 3.
[706] Bäsecke (08).
[707] Boodle (00).
[708] Yapp (02).
[709] Darwin (03) ii. p. 381.
[710] Reinecke (97).
[711] Karsten (95); Christ (96); Bommer (03).
[712] Goebel (05) p. 347.
[713] A striking example of these so-called Aphlebiae of Hemitelia may be seen at the
Royal Gardens, Kew.
[714] Luerssen, in Rabenhorst (89) A. p. 483, fig. 164.
[715] Goebel (01) Pl. xiii.
[716] Spruce (08) ii. p. 232.
[717] Boodle (04).
[718] Goebel (05); Baker (67).
[719] Seward and Gowan (00).
[720] Hooker (59).
[721] Thiselton-Dyer (05).
[722] Baker (68) p. 305.
[723] Bower (08) p. 18.
[724] Treub (88) A.; Ernst (08).
[725] Campbell (07).
Page 750
[726] Davy (07) p. 263.
[727] Bates (63) A. p. 30.
[728] Challenger Reports (85) p. 785.
[729] Tansley and Fritsch (05) p. 43; Thomas, E. N. (05).
[730] Tansley (08) p. 27.
[731] Jeffrey (98).
[732] Boodle (00).
[733] Tansley and Lulham (02).
[734] Gwynne-Vaughan (01); (03).
[735] Boodle (01) p. 735.
[736] Jeffrey (00); (03).
[737] For an account of the probable methods by which this has been effected and of the
factors concerned, see Tansley (08).
[738] Gwynne-Vaughan (03).
[739] Seward (992); Wigglesworth (02).
[740] Seward and Ford (03); Jeffrey (03); Faull (01).
[741] Kidston and Gwynne-Vaughan (07); (08); (09).
[742] Gwynne-Vaughan (08).
[743] Bertrand and Cornaille (02).
[744] Chodat (08) p. 15.
[745] See also Pelourde (09) for an account of the anatomy of fern petioles.
[746] Observed in plants in the Botanic Gardens of Brussels and Leipzig. A.C.S.
[747] For an account of the spore-producing members of the Marattiaceae, see Bower
(97).
[748] Zeiller (90) p. 19.
[749] Shove (00); Tansley (08).
[750] Farmer and Hill (02) Pl. xviii. figs. 26, 28.
[751] Christ and Giesenhagen (99).
[752] Gwynne-Vaughan (05).
[753] Hooker and Baker (68) p. 440.
[754] The term synangium is applied to sporangia more or less completely united with
one another and producing spores in groups separated by walls of sterile cells. A
synangium may be regarded as a spore-forming organ produced by partial sterilization of
sporogenous tissue or as a group of coalescent sporangia.
[755] Brebner (02); Rudolph (05).
[756] Tansley (08) p. 90; Kühn (90).
[757] Pelourde (08) has recently dealt with the anatomy of recent and fossil
Marattiaceous ferns.
[758] Copeland (08) Pl. i. (09) Pl. v.
[727] Bates (63) A. p. 30.
[728] Challenger Reports (85) p. 785.
[729] Tansley and Fritsch (05) p. 43; Thomas, E. N. (05).
[730] Tansley (08) p. 27.
[731] Jeffrey (98).
[732] Boodle (00).
[733] Tansley and Lulham (02).
[734] Gwynne-Vaughan (01); (03).
[735] Boodle (01) p. 735.
[736] Jeffrey (00); (03).
[737] For an account of the probable methods by which this has been effected and of the
factors concerned, see Tansley (08).
[738] Gwynne-Vaughan (03).
[739] Seward (992); Wigglesworth (02).
[740] Seward and Ford (03); Jeffrey (03); Faull (01).
[741] Kidston and Gwynne-Vaughan (07); (08); (09).
[742] Gwynne-Vaughan (08).
[743] Bertrand and Cornaille (02).
[744] Chodat (08) p. 15.
[745] See also Pelourde (09) for an account of the anatomy of fern petioles.
[746] Observed in plants in the Botanic Gardens of Brussels and Leipzig. A.C.S.
[747] For an account of the spore-producing members of the Marattiaceae, see Bower
(97).
[748] Zeiller (90) p. 19.
[749] Shove (00); Tansley (08).
[750] Farmer and Hill (02) Pl. xviii. figs. 26, 28.
[751] Christ and Giesenhagen (99).
[752] Gwynne-Vaughan (05).
[753] Hooker and Baker (68) p. 440.
[754] The term synangium is applied to sporangia more or less completely united with
one another and producing spores in groups separated by walls of sterile cells. A
synangium may be regarded as a spore-forming organ produced by partial sterilization of
sporogenous tissue or as a group of coalescent sporangia.
[755] Brebner (02); Rudolph (05).
[756] Tansley (08) p. 90; Kühn (90).
[757] Pelourde (08) has recently dealt with the anatomy of recent and fossil
Marattiaceous ferns.
[758] Copeland (08) Pl. i. (09) Pl. v.
Page 751
[759] Bower (96).
[760] Jeffrey (98). For an account of the anatomy of Helminthostachys, see Farmer and
Freeman (99).
[761] Stur (75) A. p. 77, Pl. xi. fig. 8.
[762] Renault (96) A. p. 21.
[763] Zeiller (90) p. 16.
[764] Zeiller (90) p. 48.
[765] Scott, D. H. (08) p. 292.
[766] Scott (04) p. 18.
[767] Boodle (00) p. 484.
[768] Zeiller (99) Pl. ii. figs. 5, 6.
[769] Ibid. Pl. ii. fig. 10.
[770] See p. 402.
[771] Bower (91) Pl. vii.
[772] Scott, D. H. (09).
[773] Kidston and Gwynne-Vaughan (08).
[774] Eichwald (60).
[775] Gwynne-Vaughan (08).
[776] Kidston and Gwynne-Vaughan (08) p. 226.
[777] Brongniart (49) A. p. 35.
[778] Brongniart (28) A. Pl. lxxx.
[779] Kidston and Gwynne-Vaughan (09).
[780] Seward (99).
[781] Krasser (09) p. 10.
[782] Fontaine (83) Pls. xxviii. xxix.
[783] Leuthardt (04) Pl. xviii.
[784] Kidston and Gwynne-Vaughan (07).
[785] See p. 343.
[786] Seward and Ford (03).
[787] Kidston and Gwynne-Vaughan (07).
[788] Seward (073) p. 482, Pls. xx. xxi.
[789] Seward (03); Kitchin (08).
[790] Cf. Todea Wilkesiana (p. 286).
[791] Penhallow (02).
[792] Kidston and Gwynne-Vaughan (07).
[793] See p. 314. Also Jeffrey (03); Faull (01); Seward and Ford (03).
[794] Raciborski (94) A. p. 19, Pls. vi. xi.
[760] Jeffrey (98). For an account of the anatomy of Helminthostachys, see Farmer and
Freeman (99).
[761] Stur (75) A. p. 77, Pl. xi. fig. 8.
[762] Renault (96) A. p. 21.
[763] Zeiller (90) p. 16.
[764] Zeiller (90) p. 48.
[765] Scott, D. H. (08) p. 292.
[766] Scott (04) p. 18.
[767] Boodle (00) p. 484.
[768] Zeiller (99) Pl. ii. figs. 5, 6.
[769] Ibid. Pl. ii. fig. 10.
[770] See p. 402.
[771] Bower (91) Pl. vii.
[772] Scott, D. H. (09).
[773] Kidston and Gwynne-Vaughan (08).
[774] Eichwald (60).
[775] Gwynne-Vaughan (08).
[776] Kidston and Gwynne-Vaughan (08) p. 226.
[777] Brongniart (49) A. p. 35.
[778] Brongniart (28) A. Pl. lxxx.
[779] Kidston and Gwynne-Vaughan (09).
[780] Seward (99).
[781] Krasser (09) p. 10.
[782] Fontaine (83) Pls. xxviii. xxix.
[783] Leuthardt (04) Pl. xviii.
[784] Kidston and Gwynne-Vaughan (07).
[785] See p. 343.
[786] Seward and Ford (03).
[787] Kidston and Gwynne-Vaughan (07).
[788] Seward (073) p. 482, Pls. xx. xxi.
[789] Seward (03); Kitchin (08).
[790] Cf. Todea Wilkesiana (p. 286).
[791] Penhallow (02).
[792] Kidston and Gwynne-Vaughan (07).
[793] See p. 314. Also Jeffrey (03); Faull (01); Seward and Ford (03).
[794] Raciborski (94) A. p. 19, Pls. vi. xi.
Page 752
[795] Carruthers (70) A.; Kidston and Gwynne-Vaughan (07) p. 768; see also Seward,
Vol. i. p. 212.
[796] Gardner and Ettingshausen (82) pp. 22, 48, Pl. iv. figs. 1–3.
[797] Seward (00) p. 86.
[798] Seward and Ford (03) p. 251.
[799] For a more complete list, see Seward (00) p. 87
[800] Schenk (85) Pl. iii. fig. 3.
[801] Raciborski (94) A. Pl. vi.
[802] Nathorst (08) Pl. i. fig. 7.
[803] Schenk (67) A.
[804] Fontaine (83).
[805] The geographical distribution of Todites and other genera will be dealt with in
Volume iii.
[806] Carruthers (70) A. p. 350.
[807] Reid (99).
[808] Seward (08) Pl. viii. p. 98.
[809] Zeiller (03) Pls. ii. iv.
[810] Leuthardt (04) Pl. xv.
[811] Fontaine (83) Pls. xi.–xiv.
[812] For synonymy and figures, see Seward (00) p. 134; (04) p. 134.
[813] E.g. by Yokoyama (06) who identifies specimens of Cladophlebis denticulata from
Jurassic rocks of China as Todites Williamsoni.
[814] Lindley and Hutton (34) A. Pl. cxxxiv.
[815] Seward (942) A. p. 91.
[816] Nathorst (78).
[817] Lindley and Hutton (34) A. Pl. cxx.
[818] Fontaine, in Ward (05) Pl. xv. figs. 6–9).
[819] Feistmantel (77) Pls. xxxvi. xxxvii.
[820] Morris (45) Pl. vii.
[821] Renault (83) p. 81, Pl. xi.
[822] Dawson (61).
[823] White (04).
[824] Corda (45) A. Pl. lvii.
[825] Zeiller (83) p. 188, Pl. x. figs. 1–5.
[826] Stur (85) A. p. 64.
[827] Zeiller (88) A. p. 50.
[828] Solms-Laubach (91) A. p. 147.
[829] For synonymy, see Seward (00) p. 130.
Vol. i. p. 212.
[796] Gardner and Ettingshausen (82) pp. 22, 48, Pl. iv. figs. 1–3.
[797] Seward (00) p. 86.
[798] Seward and Ford (03) p. 251.
[799] For a more complete list, see Seward (00) p. 87
[800] Schenk (85) Pl. iii. fig. 3.
[801] Raciborski (94) A. Pl. vi.
[802] Nathorst (08) Pl. i. fig. 7.
[803] Schenk (67) A.
[804] Fontaine (83).
[805] The geographical distribution of Todites and other genera will be dealt with in
Volume iii.
[806] Carruthers (70) A. p. 350.
[807] Reid (99).
[808] Seward (08) Pl. viii. p. 98.
[809] Zeiller (03) Pls. ii. iv.
[810] Leuthardt (04) Pl. xv.
[811] Fontaine (83) Pls. xi.–xiv.
[812] For synonymy and figures, see Seward (00) p. 134; (04) p. 134.
[813] E.g. by Yokoyama (06) who identifies specimens of Cladophlebis denticulata from
Jurassic rocks of China as Todites Williamsoni.
[814] Lindley and Hutton (34) A. Pl. cxxxiv.
[815] Seward (942) A. p. 91.
[816] Nathorst (78).
[817] Lindley and Hutton (34) A. Pl. cxx.
[818] Fontaine, in Ward (05) Pl. xv. figs. 6–9).
[819] Feistmantel (77) Pls. xxxvi. xxxvii.
[820] Morris (45) Pl. vii.
[821] Renault (83) p. 81, Pl. xi.
[822] Dawson (61).
[823] White (04).
[824] Corda (45) A. Pl. lvii.
[825] Zeiller (83) p. 188, Pl. x. figs. 1–5.
[826] Stur (85) A. p. 64.
[827] Zeiller (88) A. p. 50.
[828] Solms-Laubach (91) A. p. 147.
[829] For synonymy, see Seward (00) p. 130.
Page 753
[830] Raciborski (91).
[831] Phillips (29) A. p. 148.
[832] Bunbury (51) A.
[833] Seward (942) A.
[834] Raciborski (94) A.
[835] Yokoyama (89).
[836] Seward (942) A.
[837] Yabe (05) Pl. iii.
[838] Seward (074) Pls. i. iii.
[839] Seward (942) A. p. 75.
[840] Gardner and Ettingshausen (82) p. 47, Pls. vii. x.; Heer (55) A. Pl. iii. p. 41.
[841] Knowlton (99). Pl. lxxx.
[842] Heer (55) A. Pl. xiii.
[843] Saporta (72) A. Pl. i. figs. 13, 14.
[844] Goeppert (362) A. Pls. iv. v.
[845] Zeiller (88) A. p. 261.
[846] Williamson (77) Pl. vii.
[847] See Ch. xxvii.
[848] Goeppert (41) Pl. iv. figs. 1, 2.
[849] Zeiller (88) A. Pl. xi. figs. 3–5.
[850] Stur (85) A. p. 128.
[851] Solms-Laubach (91) A. p. 146.
[852] Schenk (88) A. p. 30.
[853] Dr Scott tells me that an examination of Dr Zeiller’s specimens led him to agree
with the latter’s description of the annulus of Oligocarpia. (A. C. S.)
[854] Fontaine (83) Pls. xv.-xix.
[855] Bunbury (47) Pl. ii. fig. 1; Seward (942) A. p. 189.
[856] Krasser (09) p. 16.
[857] Leuthardt (04) p. 40, Pl. xviii. fig. 3.
[858] Schenk (67) A. p. 86, Pl. xxii. figs. 7, 8.
[859] Zigno (56) A. Pl. x.
[860] Raciborski (94) A. p. 43, Pl. xiii. figs. 15–20.
[861] Seward (95) A. p. 225.
[862] Seward (00) Pl. iv.
[863] Schenk (71).
[864] Corda, in Reuss (46) p. 95, Pl. xlix.
[865] Heer (75), p. 44, Pls. iv.-vii.
[831] Phillips (29) A. p. 148.
[832] Bunbury (51) A.
[833] Seward (942) A.
[834] Raciborski (94) A.
[835] Yokoyama (89).
[836] Seward (942) A.
[837] Yabe (05) Pl. iii.
[838] Seward (074) Pls. i. iii.
[839] Seward (942) A. p. 75.
[840] Gardner and Ettingshausen (82) p. 47, Pls. vii. x.; Heer (55) A. Pl. iii. p. 41.
[841] Knowlton (99). Pl. lxxx.
[842] Heer (55) A. Pl. xiii.
[843] Saporta (72) A. Pl. i. figs. 13, 14.
[844] Goeppert (362) A. Pls. iv. v.
[845] Zeiller (88) A. p. 261.
[846] Williamson (77) Pl. vii.
[847] See Ch. xxvii.
[848] Goeppert (41) Pl. iv. figs. 1, 2.
[849] Zeiller (88) A. Pl. xi. figs. 3–5.
[850] Stur (85) A. p. 128.
[851] Solms-Laubach (91) A. p. 146.
[852] Schenk (88) A. p. 30.
[853] Dr Scott tells me that an examination of Dr Zeiller’s specimens led him to agree
with the latter’s description of the annulus of Oligocarpia. (A. C. S.)
[854] Fontaine (83) Pls. xv.-xix.
[855] Bunbury (47) Pl. ii. fig. 1; Seward (942) A. p. 189.
[856] Krasser (09) p. 16.
[857] Leuthardt (04) p. 40, Pl. xviii. fig. 3.
[858] Schenk (67) A. p. 86, Pl. xxii. figs. 7, 8.
[859] Zigno (56) A. Pl. x.
[860] Raciborski (94) A. p. 43, Pl. xiii. figs. 15–20.
[861] Seward (95) A. p. 225.
[862] Seward (00) Pl. iv.
[863] Schenk (71).
[864] Corda, in Reuss (46) p. 95, Pl. xlix.
[865] Heer (75), p. 44, Pls. iv.-vii.
Page 754
[866] Debey and Ettingshausen (59) Pl. i.
[867] Gardner and Ettingshausen (82), pp. 43, 59, Pls. vi. x.
[868] Wanklyn (69).
[869] Presl, in Sternberg (38) A. p. 115.
[870] Schenk (67) A.
[871] Zeiller (85).
[872] Seward (992) p. 194.
[873] Schenk (67) A. Pls. xxiii. xxiv.
[874] For a more complete list, see Seward (00) p. 78.
[875] Leckenby (64) A. p. 81, Pl. viii. fig. 6. (Type-specimen in the Sedgwick Museum,
Cambridge.)
[876] Saporta (73) A. p. 306.
[877] Debey and Ettingshausen (59) Pl. iii.
[878] See Seward (942) A. and (00) for an account of this fern.
[879] Schenk (71) p. 219.
[880] Zeiller (85).
[881] Ettingshausen (52) p. 16, Pl. v. For synonymy, see Seward (942) A; (00).
[882] Fontaine, in Ward (05) p. 230.
[883] Schenk (71) p. 19.
[884] Fontaine, loc. cit. Pl. lxv. figs. 22, 23.
[885] Krasser (96) p. 119, Pls. xi. xii. xiv.
[886] Stur (75) A. p. 284, Pl. xxxiii. fig. 15.
[887] Renault (96) A. p. 19.
[888] Ettingshausen (66) Pl. vii. fig. 4.
[889] Stur (75) A. p. 36, Pl. ix. figs. 1–9.
[890] Schimper (74) A. Pl. xxviii. fig. 4–7.
[891] Solms-Laubach (91) A. p. 153.
[892] Zeiller (83) p. 155; (88) A. Pl. viii. figs. 1–3.
[893] Kidston (842) p. 593.
[894] See p. 450.
[895] Scott (08) p. 343.
[896] Stur (75) A. p. 19, Pl. x. figs. 1, 2.
[897] Goeppert (362) A. pp. 319, 320, 329.
[898] Sterzel (86).
[899] Grand’Eury (05).
[900] Zeiller (06) Pls. ii. iii.
[901] Raciborski (94) A. Pl. ix.
[867] Gardner and Ettingshausen (82), pp. 43, 59, Pls. vi. x.
[868] Wanklyn (69).
[869] Presl, in Sternberg (38) A. p. 115.
[870] Schenk (67) A.
[871] Zeiller (85).
[872] Seward (992) p. 194.
[873] Schenk (67) A. Pls. xxiii. xxiv.
[874] For a more complete list, see Seward (00) p. 78.
[875] Leckenby (64) A. p. 81, Pl. viii. fig. 6. (Type-specimen in the Sedgwick Museum,
Cambridge.)
[876] Saporta (73) A. p. 306.
[877] Debey and Ettingshausen (59) Pl. iii.
[878] See Seward (942) A. and (00) for an account of this fern.
[879] Schenk (71) p. 219.
[880] Zeiller (85).
[881] Ettingshausen (52) p. 16, Pl. v. For synonymy, see Seward (942) A; (00).
[882] Fontaine, in Ward (05) p. 230.
[883] Schenk (71) p. 19.
[884] Fontaine, loc. cit. Pl. lxv. figs. 22, 23.
[885] Krasser (96) p. 119, Pls. xi. xii. xiv.
[886] Stur (75) A. p. 284, Pl. xxxiii. fig. 15.
[887] Renault (96) A. p. 19.
[888] Ettingshausen (66) Pl. vii. fig. 4.
[889] Stur (75) A. p. 36, Pl. ix. figs. 1–9.
[890] Schimper (74) A. Pl. xxviii. fig. 4–7.
[891] Solms-Laubach (91) A. p. 153.
[892] Zeiller (83) p. 155; (88) A. Pl. viii. figs. 1–3.
[893] Kidston (842) p. 593.
[894] See p. 450.
[895] Scott (08) p. 343.
[896] Stur (75) A. p. 19, Pl. x. figs. 1, 2.
[897] Goeppert (362) A. pp. 319, 320, 329.
[898] Sterzel (86).
[899] Grand’Eury (05).
[900] Zeiller (06) Pls. ii. iii.
[901] Raciborski (94) A. Pl. ix.
Page 755
[902] Brongniart (49) A. p. 26.
[903] Krasser (09).
[904] For fuller synonymy see Seward (00) p. 97.
[905] Heer (76).
[906] Fontaine (89).
[907] Fontaine (89) p. 123, Pls. xxvi. xliii. etc.
[908] Ward (99) Pl. clxi.
[909] Velenovský (88).
[910] Heer (75) A. Pl. i. figs. 6, 7.
[911] Heer (82) A. Pl. ii. fig. 2.
[912] Phillips (75) A. p. 215.
[913] Seward (00).
[914] Sternberg (38) A. p. 169.
[915] Sternberg (20) A. Pl. iv.
[916] Corda (45) A. Pl. ii. fig. 5.
[917] Brongniart (28) A. Pl. xli.
[918] Feistmantel (72).
[919] Velenovský (88).
[920] Carruthers (65) Pl. xiii.
[921] Heer (75).
[922] Heer (82) Pl. xlvii.
[923] Frič and Bayer (01) p. 76.
[924] Stenzel (86). See also Stenzel (97).
[925] Gwynne-Vaughan (08).
[926] Schenk (71) Pl. xxx.; Seward (942) A. Pl. xi.
[927] Scott (08) p. 293.
[928] Goeppert (30) A. p. 217.
[929] Schimper (69) A. p. 424.
[930] Ettingshausen (66).
[931] Kidston (893) Pl. i.
[932] White (04).
[933] Schenk (67) A. Pl. xiii.; Zeiller (03) p. 91, Pl. xvii.
[934] Seward (042) p. 162, Pl. viii. fig. 5.
[935] Yabe (05) p. 39, Pl. i. figs. 1–8.
[936] Fontaine, in Ward (05) p. 64.
[937] Yokoyama (89), p. 26.
[938] Geyler (77) Pl. xxxi. fig. 4.
[903] Krasser (09).
[904] For fuller synonymy see Seward (00) p. 97.
[905] Heer (76).
[906] Fontaine (89).
[907] Fontaine (89) p. 123, Pls. xxvi. xliii. etc.
[908] Ward (99) Pl. clxi.
[909] Velenovský (88).
[910] Heer (75) A. Pl. i. figs. 6, 7.
[911] Heer (82) A. Pl. ii. fig. 2.
[912] Phillips (75) A. p. 215.
[913] Seward (00).
[914] Sternberg (38) A. p. 169.
[915] Sternberg (20) A. Pl. iv.
[916] Corda (45) A. Pl. ii. fig. 5.
[917] Brongniart (28) A. Pl. xli.
[918] Feistmantel (72).
[919] Velenovský (88).
[920] Carruthers (65) Pl. xiii.
[921] Heer (75).
[922] Heer (82) Pl. xlvii.
[923] Frič and Bayer (01) p. 76.
[924] Stenzel (86). See also Stenzel (97).
[925] Gwynne-Vaughan (08).
[926] Schenk (71) Pl. xxx.; Seward (942) A. Pl. xi.
[927] Scott (08) p. 293.
[928] Goeppert (30) A. p. 217.
[929] Schimper (69) A. p. 424.
[930] Ettingshausen (66).
[931] Kidston (893) Pl. i.
[932] White (04).
[933] Schenk (67) A. Pl. xiii.; Zeiller (03) p. 91, Pl. xvii.
[934] Seward (042) p. 162, Pl. viii. fig. 5.
[935] Yabe (05) p. 39, Pl. i. figs. 1–8.
[936] Fontaine, in Ward (05) p. 64.
[937] Yokoyama (89), p. 26.
[938] Geyler (77) Pl. xxxi. fig. 4.
Page 756
[939] For synonymy, see Fontaine, in Ward (05) p. 155; Richter (06) p. 6; Seward (94)
A. p. 41; (03) p. 5.
[940] Seward (94) A. p. 52.
[941] Gardner and Ettingshausen (82) Pls. i. ii.
[942] Forbes (51); Gardner and Ettingshausen (82).
[943] Knowlton (02) Pl. xxvi.
[944] Saporta (68) A.; Gardner and Ettingshausen (82) Pl. x. fig. 1.
[945] Gardner and Ettingshausen (82) p. 21.
[946] Lindley and Hutton (34) A. Pl. civ.
[947] Nathorst (063).
[948] Seward and Dale (01) p. 505.
[949] Zeiller (03) p. 109, Pls. xxiii.–xxviii.
[950] Seward (00) p. 122.
[951] Nathorst (063).
[952] Krasser (09) p. 111.
[953] Goeppert (41).
[954] Seward and Dale (01) p. 503.
[955] Nathorst (072).
[956] Schenk (67) A. Pl. xviii.
[957] Zeiller (03).
[958] Brongniart (25).
[959] Brongniart (25).
[960] Zeiller (03).
[961] Seward (04) pp. 18, 164.
[962] Seward (07).
[963] The evidence of the shells is stated by Mr R. B. Newton (09) to be in favour of the
Cretaceous age of the Nubian Sandstone.
[964] Nathorst (78) p. 33.
[965] Nathorst (062) p. 15.
[966] Richter (06).
[967] Dunker (46) A. p. 12.
[968] Andrae (53) A.
[969] Zigno (56) A. ix. fig. 2.
[970] Nathorst (782) Pl. ix. fig. 2.
[971] Zeiller (974) p. 51.
[972] Seward and Dale (01).
[973] Dunker (46) A., Pl. v. fig. 1.
[974] Bartholin (92) Pls. xi. xii.
A. p. 41; (03) p. 5.
[940] Seward (94) A. p. 52.
[941] Gardner and Ettingshausen (82) Pls. i. ii.
[942] Forbes (51); Gardner and Ettingshausen (82).
[943] Knowlton (02) Pl. xxvi.
[944] Saporta (68) A.; Gardner and Ettingshausen (82) Pl. x. fig. 1.
[945] Gardner and Ettingshausen (82) p. 21.
[946] Lindley and Hutton (34) A. Pl. civ.
[947] Nathorst (063).
[948] Seward and Dale (01) p. 505.
[949] Zeiller (03) p. 109, Pls. xxiii.–xxviii.
[950] Seward (00) p. 122.
[951] Nathorst (063).
[952] Krasser (09) p. 111.
[953] Goeppert (41).
[954] Seward and Dale (01) p. 503.
[955] Nathorst (072).
[956] Schenk (67) A. Pl. xviii.
[957] Zeiller (03).
[958] Brongniart (25).
[959] Brongniart (25).
[960] Zeiller (03).
[961] Seward (04) pp. 18, 164.
[962] Seward (07).
[963] The evidence of the shells is stated by Mr R. B. Newton (09) to be in favour of the
Cretaceous age of the Nubian Sandstone.
[964] Nathorst (78) p. 33.
[965] Nathorst (062) p. 15.
[966] Richter (06).
[967] Dunker (46) A. p. 12.
[968] Andrae (53) A.
[969] Zigno (56) A. ix. fig. 2.
[970] Nathorst (782) Pl. ix. fig. 2.
[971] Zeiller (974) p. 51.
[972] Seward and Dale (01).
[973] Dunker (46) A., Pl. v. fig. 1.
[974] Bartholin (92) Pls. xi. xii.
Page 757
[975] Moeller (02) Pls. iv.-vi.
[976] Richter (06) p. 21.
[977] Richter (06) p. 22.
[978] Andrae (53) A.
[979] Moeller (02) Pls. iv.–vi.
[980] Nathorst (782) Pl. ix. fig. 2.
[981] Zeiller (79).
[982] Gardner and Ettingshausen (82) p. 29, Pl. iii. fig. 6.
[983] Arber (06) p. 227.
[984] Scott (06) p. 189.
[985] Zeiller (05).
[986] Kidston (06).
[987] Kidston (06) p. 429.
[988] Weiss, C. E. (69) p. 94, Pl. xi. fig. 2. The specimens figured by Weiss bear a
somewhat remote resemblance to that described by Renault (96) A, under the same
generic name.
[989] Kidston (912) p. 23.
[990] Kidston (88) p. 350.
[991] Renault (96) A. p. 9; Zeiller (88) A. p. 162; Grand’Eury (77) A. Pl. viii. fig. 13.
[992] Watson (06).
[993] Goeppert (362) A. p. 380.
[994] Stur (85) A. p. 221, Pl. lxi.; Zeiller (88) A. p. 41.
[995] Grand’Eury (90) A. p. 288, Pl. vi. fig. 26.
[996] For an account of these genera, see Chap. xxvii.
[997] Strasburger (74).
[998] Stur (85) A. p. 183.
[999] Corda (45) A. Pl. lvii.
[1000] Kidston (912) p. 20; Stur (85) A. Pl. lix.
[1001] See Chap. xxvii.
[1002] Stur (85) A. p. 106.
[1003] Zenker (37).
[1004] Strasburger (74).
[1005] Kidston (912) p. 20.
[1006] Geinitz (72). See Solms-Laubach (83), who gives in full the early history of the
genus Scolecopteris.
[1007] Sterzel (78); (80).
[1008] Stur (85) p. 140.
[1009] Zeiller (99) p. 17.
[976] Richter (06) p. 21.
[977] Richter (06) p. 22.
[978] Andrae (53) A.
[979] Moeller (02) Pls. iv.–vi.
[980] Nathorst (782) Pl. ix. fig. 2.
[981] Zeiller (79).
[982] Gardner and Ettingshausen (82) p. 29, Pl. iii. fig. 6.
[983] Arber (06) p. 227.
[984] Scott (06) p. 189.
[985] Zeiller (05).
[986] Kidston (06).
[987] Kidston (06) p. 429.
[988] Weiss, C. E. (69) p. 94, Pl. xi. fig. 2. The specimens figured by Weiss bear a
somewhat remote resemblance to that described by Renault (96) A, under the same
generic name.
[989] Kidston (912) p. 23.
[990] Kidston (88) p. 350.
[991] Renault (96) A. p. 9; Zeiller (88) A. p. 162; Grand’Eury (77) A. Pl. viii. fig. 13.
[992] Watson (06).
[993] Goeppert (362) A. p. 380.
[994] Stur (85) A. p. 221, Pl. lxi.; Zeiller (88) A. p. 41.
[995] Grand’Eury (90) A. p. 288, Pl. vi. fig. 26.
[996] For an account of these genera, see Chap. xxvii.
[997] Strasburger (74).
[998] Stur (85) A. p. 183.
[999] Corda (45) A. Pl. lvii.
[1000] Kidston (912) p. 20; Stur (85) A. Pl. lix.
[1001] See Chap. xxvii.
[1002] Stur (85) A. p. 106.
[1003] Zenker (37).
[1004] Strasburger (74).
[1005] Kidston (912) p. 20.
[1006] Geinitz (72). See Solms-Laubach (83), who gives in full the early history of the
genus Scolecopteris.
[1007] Sterzel (78); (80).
[1008] Stur (85) p. 140.
[1009] Zeiller (99) p. 17.
Page 758
[1010] Zeiller (06) p. 10.
[1011] Brongniart (28) A. Pl. cxxv. fig. 4.
[1012] Renault and Zeiller (88) A. Pl. xxiv.
[1013] page 325.
[1014] Zeiller (83) p. 184; (88) A. p. 30.
[1015] Artis (25) A.
[1016] Stur (75) A.
[1017] Kidston (96) p. 205.
[1018] Zeiller (83) p. 185.
[1019] Kidston (82).
[1020] Stur (85).
[1021] Kidston (842).
[1022] Kidston (87).
[1023] Kidston (82) p. 32.
[1024] Kidston (842) p. 594.
[1025] Williamson (83) A.
[1026] Kidston (06).
[1027] Heer (76) A. p. 71, Pl. xxiv. fig. 1.
[1028] Schimper (74) A. Pl. 38; see also Schenk (88) A. p. 31.
[1029] Leuthardt (04) p. 29, Pl. xiii. figs. 1, 2.
[1030] Goeppert (362) A. Lief. i. and ii. Pl. iv.
[1031] Schimper (69) A. p. 607.
[1032] Schenk (83) A. p. 260.
[1033] Zeiller (03) Pl. ix.
[1034] Fontaine, in Ward (00) Pl. lv. figs. 3–5.
[1035] Bartholin (92) Pl. ix.
[1036] Moeller (02).
[1037] Schenk (83) A.
[1038] Seward (074) Pl. ii. figs. 16–18.
[1039] Nathorst (08).
[1040] Krasser (09).
[1041] Feistmantel (82) Pls. iv.-x.
[1042] Seward (08) p. 95.
[1043] Krasser (00) Pl. ii.
[1044] Zeiller (03) Pl. ix.
[1045] Krasser (09) p. 21.
[1046] Leuthardt (04) Pls. xix. xx.
[1011] Brongniart (28) A. Pl. cxxv. fig. 4.
[1012] Renault and Zeiller (88) A. Pl. xxiv.
[1013] page 325.
[1014] Zeiller (83) p. 184; (88) A. p. 30.
[1015] Artis (25) A.
[1016] Stur (75) A.
[1017] Kidston (96) p. 205.
[1018] Zeiller (83) p. 185.
[1019] Kidston (82).
[1020] Stur (85).
[1021] Kidston (842).
[1022] Kidston (87).
[1023] Kidston (82) p. 32.
[1024] Kidston (842) p. 594.
[1025] Williamson (83) A.
[1026] Kidston (06).
[1027] Heer (76) A. p. 71, Pl. xxiv. fig. 1.
[1028] Schimper (74) A. Pl. 38; see also Schenk (88) A. p. 31.
[1029] Leuthardt (04) p. 29, Pl. xiii. figs. 1, 2.
[1030] Goeppert (362) A. Lief. i. and ii. Pl. iv.
[1031] Schimper (69) A. p. 607.
[1032] Schenk (83) A. p. 260.
[1033] Zeiller (03) Pl. ix.
[1034] Fontaine, in Ward (00) Pl. lv. figs. 3–5.
[1035] Bartholin (92) Pl. ix.
[1036] Moeller (02).
[1037] Schenk (83) A.
[1038] Seward (074) Pl. ii. figs. 16–18.
[1039] Nathorst (08).
[1040] Krasser (09).
[1041] Feistmantel (82) Pls. iv.-x.
[1042] Seward (08) p. 95.
[1043] Krasser (00) Pl. ii.
[1044] Zeiller (03) Pl. ix.
[1045] Krasser (09) p. 21.
[1046] Leuthardt (04) Pls. xix. xx.
Page 759
[1047] Zigno (56) A. Pl. xxv.
[1048] Raciborski (94) A. Pl. vi.
[1049] Heer (80).
[1050] Nathorst (08).
[1051] Bayer (99).
[1052] Gardner and Ettingshausen (82) Pl. xii. figs. 1–7.
[1053] Stenzel (54) p. 803.
[1054] Cotta (32).
[1055] Sprengel (28).
[1056] Stenzel (54) p. 753.
[1057] Parkinson (11) A.
[1058] Williamson (76).
[1059] Scott (08).
[1060] Butterworth (00).
[1061] Grand’Eury (77) A.
[1062] Grand’Eury (77) A; (90) A.
[1063] Rudolph (05).
[1064] Scott (08) p. 302.
[1065] Butterworth (00). Pelourde (082) has recently described the structure of the roots
of several species of Psaronius.
[1066] Stenzel (06).
[1067] Farmer and Hill (02).
[1068] Williamson (76) Pl. iii.
[1069] Stenzel (89) Pl. vi.
[1070] Zeiller (90) p. 204, Pls. xvi. xvii.; see also Rudolph (05).
[1071] Renault and Zeiller (88) A. Pls. v.–viii.
[1072] Solms-Laubach (04).
[1073] Arber (05) Pl. vii.
[1074] Scott (08) fig. 113; Zeiller (90) p. 246, Pl. xxi. fig. 1.
[1075] Pelourde (082).
[1076] Stenzel (06) Pl. vi.; Goeppert (64) A.; Stenzel (06).
[1077] Zeiller (90) Pl. xxiii.
[1078] Scott (08) p. 301.
[1079] Lindley and Hutton (33) A. Pl. xlii.
[1080] Kidston (88) Pl. xxvi.
[1081] Renault and Zeiller (88) A. Pl. xxxv. fig. 6.
[1082] Kidston (86) A. p. 113.
[1048] Raciborski (94) A. Pl. vi.
[1049] Heer (80).
[1050] Nathorst (08).
[1051] Bayer (99).
[1052] Gardner and Ettingshausen (82) Pl. xii. figs. 1–7.
[1053] Stenzel (54) p. 803.
[1054] Cotta (32).
[1055] Sprengel (28).
[1056] Stenzel (54) p. 753.
[1057] Parkinson (11) A.
[1058] Williamson (76).
[1059] Scott (08).
[1060] Butterworth (00).
[1061] Grand’Eury (77) A.
[1062] Grand’Eury (77) A; (90) A.
[1063] Rudolph (05).
[1064] Scott (08) p. 302.
[1065] Butterworth (00). Pelourde (082) has recently described the structure of the roots
of several species of Psaronius.
[1066] Stenzel (06).
[1067] Farmer and Hill (02).
[1068] Williamson (76) Pl. iii.
[1069] Stenzel (89) Pl. vi.
[1070] Zeiller (90) p. 204, Pls. xvi. xvii.; see also Rudolph (05).
[1071] Renault and Zeiller (88) A. Pls. v.–viii.
[1072] Solms-Laubach (04).
[1073] Arber (05) Pl. vii.
[1074] Scott (08) fig. 113; Zeiller (90) p. 246, Pl. xxi. fig. 1.
[1075] Pelourde (082).
[1076] Stenzel (06) Pl. vi.; Goeppert (64) A.; Stenzel (06).
[1077] Zeiller (90) Pl. xxiii.
[1078] Scott (08) p. 301.
[1079] Lindley and Hutton (33) A. Pl. xlii.
[1080] Kidston (88) Pl. xxvi.
[1081] Renault and Zeiller (88) A. Pl. xxxv. fig. 6.
[1082] Kidston (86) A. p. 113.
Page 760
[1083] Artis (25) A. Pl. xx.
[1084] Lesquereux (66) A.
[1085] Renault and Zeiller (88) A. Pl. xl.; Grand’Eury (90) A.
[1086] Corda (45) A.; see also Grand’Eury (90) A.; Renault and Zeiller (88) A. Pls.
xxxviii.–xl.
[1087] Fontaine and White (80) Pl. xxxvi.; Zeiller (90) Pl. xiv.
[1088] Mettenius (65); Tansley (08) p. 85.
[1089] Rudolph (05).
[1090] Scott, D. H. (08).
[1091] Shove (00).
[1092] Butterworth (00).
[1093] Farmer and Hill (02).
[1094] Grand’Eury (77) A. p. 98.
[1095] Stur (75) A. Pl. viii.
[1096] Zeiller (00) p. 55.
[1097] Kidston (893), Pls. i. ii. For other figures of Rhacopteris see also Stur (75) A.
[1098] Renault (96) A. p. 30, Pl. lxxxii. figs. 7–9.
[1099] Stur (75) A.
[1100] Weiss, C. E. (79).
[1101] Solms-Laubach (91) A. p. 141.
[1102] O. Feistmantel (75).
[1103] C. Feistmantel (79).
[1104] C. E. Weiss (79).
[1105] Potonié (99) p. 167.
[1106] Seward (03) p. 63.
[1107] Carruthers (722) Pl. xxvii. fig. 5; Seward (03) p. 62.
[1108] Newberry (91) Pl. xiv.
[1109] D. H. Scott (08).
[1110] P. Bertrand (09).
[1111] Scott (092).
[1112] Williamson (832) A, p. 478.
[1113] κοινός = Lat. communis, common or general. I am indebted to my friend Mr L. H.
G. Greenwood, Fellow of Emmanuel College, for supplying me with a name to express
the idea of the generalized nature of these Palaeozoic ferns.
[1114] Arber (06).
[1115] Renault (96) A. p. 46, Pls. xxx. xxxi. See also Tansley (08) fig. 2, p. 13.
[1116] Cotta (32) p. 15.
[1117] Stenzel (89) Pls. i. ii.
[1084] Lesquereux (66) A.
[1085] Renault and Zeiller (88) A. Pl. xl.; Grand’Eury (90) A.
[1086] Corda (45) A.; see also Grand’Eury (90) A.; Renault and Zeiller (88) A. Pls.
xxxviii.–xl.
[1087] Fontaine and White (80) Pl. xxxvi.; Zeiller (90) Pl. xiv.
[1088] Mettenius (65); Tansley (08) p. 85.
[1089] Rudolph (05).
[1090] Scott, D. H. (08).
[1091] Shove (00).
[1092] Butterworth (00).
[1093] Farmer and Hill (02).
[1094] Grand’Eury (77) A. p. 98.
[1095] Stur (75) A. Pl. viii.
[1096] Zeiller (00) p. 55.
[1097] Kidston (893), Pls. i. ii. For other figures of Rhacopteris see also Stur (75) A.
[1098] Renault (96) A. p. 30, Pl. lxxxii. figs. 7–9.
[1099] Stur (75) A.
[1100] Weiss, C. E. (79).
[1101] Solms-Laubach (91) A. p. 141.
[1102] O. Feistmantel (75).
[1103] C. Feistmantel (79).
[1104] C. E. Weiss (79).
[1105] Potonié (99) p. 167.
[1106] Seward (03) p. 63.
[1107] Carruthers (722) Pl. xxvii. fig. 5; Seward (03) p. 62.
[1108] Newberry (91) Pl. xiv.
[1109] D. H. Scott (08).
[1110] P. Bertrand (09).
[1111] Scott (092).
[1112] Williamson (832) A, p. 478.
[1113] κοινός = Lat. communis, common or general. I am indebted to my friend Mr L. H.
G. Greenwood, Fellow of Emmanuel College, for supplying me with a name to express
the idea of the generalized nature of these Palaeozoic ferns.
[1114] Arber (06).
[1115] Renault (96) A. p. 46, Pls. xxx. xxxi. See also Tansley (08) fig. 2, p. 13.
[1116] Cotta (32) p. 15.
[1117] Stenzel (89) Pls. i. ii.
Page 761
[1118] Stopes (06).
[1119] Williamson (89) A. p. 162. The term Rachiopteris was adopted by Williamson for
petrified petioles from the Coal-Measures which he believed to be filicinean.
[1120] Renault (75); (96) A. p. 47, Pl. xxxii.
[1121] Oliver (02).
[1122] Oliver (04) p. 395 (footnote).
[1123] Scott, D. H. (08).
[1124] Felix (86) A.
[1125] Williamson (78) A. p. 351.
[1126] Hick (96).
[1127] Scott (08).
[1128] Williamson (912) A. p. 261. The two species described by Williamson as
Rachiopteris hirsuta and R. ramosa were first identified as Botryopteris by Scott in 1898
(British Assoc. Report, Bristol Meeting, p. 1050).
[1129] Tansley (08) p. 15.
[1130] Kidston (08).
[1131] Oliver (02).
[1132] Corda (45) A.; see also Stenzel (89) p. 26.
[1133] P. Bertrand (09) pp. 136, 212.
[1134] Tansley (08) p. 22.
[1135] Unger and Richter (56) Pl. vi. fig. 19.
[1136] Renault (96) A. p. 11.
[1137] The Diplolabis type of strand is very similar in the form of the metaxylem to the
conducting strand of a lateral vein in Scolopendrium officinarum [cf. Pelourde (09) fig.
3, p. 117].
[1138] Solms-Laubach (92).
[1139] Williamson (74) A. Pls. liv. lv.
[1140] Gordon (09). Mr Gordon’s more complete account of this plant will shortly be
published. I am indebted to him for furnishing me with the main facts in regard to the
anatomical features.
[1141] Solms-Laubach (92) Pl. ii. fig. 13.
[1142] Bertrand, P. (09) p. 211.
[1143] Pelourde (09).
[1144] Kidston and Gwynne-Vaughan (08) p. 230.
[1145] Ibid. (09) p. 664.
[1146] A Culm species Rachiopteris aphyllus (Unger) is closely allied to
Metaclepsydropsis duplex. [See Solms-Laubach (96) p. 30.]
[1147] Unger and Richter (56) p. 165.
[1148] Corda (45) A. p. 83.
[1119] Williamson (89) A. p. 162. The term Rachiopteris was adopted by Williamson for
petrified petioles from the Coal-Measures which he believed to be filicinean.
[1120] Renault (75); (96) A. p. 47, Pl. xxxii.
[1121] Oliver (02).
[1122] Oliver (04) p. 395 (footnote).
[1123] Scott, D. H. (08).
[1124] Felix (86) A.
[1125] Williamson (78) A. p. 351.
[1126] Hick (96).
[1127] Scott (08).
[1128] Williamson (912) A. p. 261. The two species described by Williamson as
Rachiopteris hirsuta and R. ramosa were first identified as Botryopteris by Scott in 1898
(British Assoc. Report, Bristol Meeting, p. 1050).
[1129] Tansley (08) p. 15.
[1130] Kidston (08).
[1131] Oliver (02).
[1132] Corda (45) A.; see also Stenzel (89) p. 26.
[1133] P. Bertrand (09) pp. 136, 212.
[1134] Tansley (08) p. 22.
[1135] Unger and Richter (56) Pl. vi. fig. 19.
[1136] Renault (96) A. p. 11.
[1137] The Diplolabis type of strand is very similar in the form of the metaxylem to the
conducting strand of a lateral vein in Scolopendrium officinarum [cf. Pelourde (09) fig.
3, p. 117].
[1138] Solms-Laubach (92).
[1139] Williamson (74) A. Pls. liv. lv.
[1140] Gordon (09). Mr Gordon’s more complete account of this plant will shortly be
published. I am indebted to him for furnishing me with the main facts in regard to the
anatomical features.
[1141] Solms-Laubach (92) Pl. ii. fig. 13.
[1142] Bertrand, P. (09) p. 211.
[1143] Pelourde (09).
[1144] Kidston and Gwynne-Vaughan (08) p. 230.
[1145] Ibid. (09) p. 664.
[1146] A Culm species Rachiopteris aphyllus (Unger) is closely allied to
Metaclepsydropsis duplex. [See Solms-Laubach (96) p. 30.]
[1147] Unger and Richter (56) p. 165.
[1148] Corda (45) A. p. 83.
Page 762
[1149] κλεψύδρα, water-clock.
[1150] P. Bertrand (09) p. 127.
[1151] Stenzel (89) p. 25.
[1152] Dr Scott points out to me that recent observations, which have not yet been
published, both by Dr Kidston and himself show that Bertrand’s terminology requires
modification. There are many points to be cleared up before we can hope to obtain a
satisfactory classification of the Zygoptereae.
[1153] Stenzel (89) p. 31, Pls. vi. vii.
[1154] Williamson (89) A. p. 158.
[1155] Ibid.; see also Scott (08).
[1156] Scott (07) p. 180.
[1157] Renault (69); Williamson (74) A. p. 697.
[1158] Williamson (77) Pls. v.–vii.
[1159] Williamson (89) A. Pl. viii. fig. 28.
[1160] Scott (08) p. 322.
[1161] No. 245.
[1162] Williamson (80) A. p. 507.
[1163] Scott (06).
[1164] Solms-Laubach (96).
[1165] Scott, D. H. (06) p. 519.
[1166] British Museum, section No. 245. Cf. figures by Williamson and Bertrand:
Williamson (77) Pl. v. fig. 19; Bertrand, P. (09) Pl. xii. fig. 87.
[1167] Scott (07) p. 182; (08) p. 318.
[1168] Weiss, F. E. (06).
[1169] Williamson (77).
[1150] P. Bertrand (09) p. 127.
[1151] Stenzel (89) p. 25.
[1152] Dr Scott points out to me that recent observations, which have not yet been
published, both by Dr Kidston and himself show that Bertrand’s terminology requires
modification. There are many points to be cleared up before we can hope to obtain a
satisfactory classification of the Zygoptereae.
[1153] Stenzel (89) p. 31, Pls. vi. vii.
[1154] Williamson (89) A. p. 158.
[1155] Ibid.; see also Scott (08).
[1156] Scott (07) p. 180.
[1157] Renault (69); Williamson (74) A. p. 697.
[1158] Williamson (77) Pls. v.–vii.
[1159] Williamson (89) A. Pl. viii. fig. 28.
[1160] Scott (08) p. 322.
[1161] No. 245.
[1162] Williamson (80) A. p. 507.
[1163] Scott (06).
[1164] Solms-Laubach (96).
[1165] Scott, D. H. (06) p. 519.
[1166] British Museum, section No. 245. Cf. figures by Williamson and Bertrand:
Williamson (77) Pl. v. fig. 19; Bertrand, P. (09) Pl. xii. fig. 87.
[1167] Scott (07) p. 182; (08) p. 318.
[1168] Weiss, F. E. (06).
[1169] Williamson (77).
Page 763
[1170] Williamson (88) A.
[1171] Jordan (03).
[1172] McNicol (08).
[1173] Gwynne-Vaughan (09).
[1174] Compare figures of the vascular cylinders of climbing Dicotyledons given by
Schenck (93).
[1175] For a figure of the stele see Tansley (08) p. 25, fig. 20.
[1176] Stenzel (89) Pls. iii. and iv.
[1177] Binney (72).
[1178] Williamson (74) A.
[1179] Bertrand, P. (09).
[1180] Felix (86) A.
[1181] Renault (69).
[1182] Grand’Eury (77) A. Pl. xvii.
[1183] Renault and Zeiller (88) A.
[1184] White (99) p. 97.
[1185] Binney (72); Williamson (74) A. p. 685.
[1186] Williamson (74) A. p. 685.
[1187] Bertrand, P. (09) Pl. vii. fig. 48.
[1188] Scott (053) p. 115.
[1189] Bertrand, P. (09) Pl. vii.
[1190] Scott (04); (053).
[1191] Scott (062).
[1192] Boodle (08).
[1193] Scott, R. (08) Pl. xxxiv. figs. 1, 2.
[1194] Baily (60) Pl. xxi. κορύνη, a club or mace.
[1195] Zeiller (83).
[1196] Kidston (94).
[1197] Potonié (02) p. 492.
[1198] Zeiller (88) A. Pl. x.
[1199] Tansley (08).
[1200] See p. 447.
[1201] Stenzel (89) p. 15, Pls. iii. iv.
[1202] Lindman (04).
[1203] Baker (87) A.; Sadebeck, in Engler and Prantl (02).
[1171] Jordan (03).
[1172] McNicol (08).
[1173] Gwynne-Vaughan (09).
[1174] Compare figures of the vascular cylinders of climbing Dicotyledons given by
Schenck (93).
[1175] For a figure of the stele see Tansley (08) p. 25, fig. 20.
[1176] Stenzel (89) Pls. iii. and iv.
[1177] Binney (72).
[1178] Williamson (74) A.
[1179] Bertrand, P. (09).
[1180] Felix (86) A.
[1181] Renault (69).
[1182] Grand’Eury (77) A. Pl. xvii.
[1183] Renault and Zeiller (88) A.
[1184] White (99) p. 97.
[1185] Binney (72); Williamson (74) A. p. 685.
[1186] Williamson (74) A. p. 685.
[1187] Bertrand, P. (09) Pl. vii. fig. 48.
[1188] Scott (053) p. 115.
[1189] Bertrand, P. (09) Pl. vii.
[1190] Scott (04); (053).
[1191] Scott (062).
[1192] Boodle (08).
[1193] Scott, R. (08) Pl. xxxiv. figs. 1, 2.
[1194] Baily (60) Pl. xxi. κορύνη, a club or mace.
[1195] Zeiller (83).
[1196] Kidston (94).
[1197] Potonié (02) p. 492.
[1198] Zeiller (88) A. Pl. x.
[1199] Tansley (08).
[1200] See p. 447.
[1201] Stenzel (89) p. 15, Pls. iii. iv.
[1202] Lindman (04).
[1203] Baker (87) A.; Sadebeck, in Engler and Prantl (02).
Page 764
[1204] Campbell (04); Bower (08) p. 551.
[1205] Schenk (71) p. 225.
[1206] Hollick (94) Pl. lxxi.
[1207] Mentioned by Krasser (06) in a preliminary note.
[1208] Frič and Bayer (01) p. 86, fig. 34.
[1209] Heer (82) Pl. xvi.
[1210] Heer (55) A. Vol. iii. p. 156, Pl. cxlv. fig. 35.
[1211] Goebel (05).
[1212] See Seward (94) p. 441, for a description of the floating plants on the lagunas of
Gran Chaco (S. America) by Prof. Graham Kerr.
[1213] Bower (08) p. 611.
[1214] Hollick (94).
[1215] E.g. Lesquereux (78) Pl. lxiv. fig. 14; Pl. v. fig. 10. Staub (87) Pl. xix. fig. 2.
[1216] Zeiller (03) Pl. li. figs. 2, 3.
[1217] Heer (55) A. Vol. iii. p. 156, Pl. cxlv. figs. 1–315.
[1218] Zeiller (092) p. 95.
[1219] Fritel (08).
[1220] See also Arber (06) p. 228.
[1221] Solms-Laubach (91) A. p. 183.
[1222] Dawson (86).
[1223] Zeiller (88) A. p. 58.
[1224] Corda (45) A. Pl. liv.
[1225] Presl, in Sternberg (38) A.
[1226] Schimper (69) A.
[1227] Nathorst (78) p. 17.
[1228] Zigno (56) A. Pl. xx.
[1229] Salfeld (09) p. 17.
[1230] In a footnote to Fontaine’s description of Jurassic plants of Oregon, Lester Ward
writes:—“Seward treats Sagenopteris as a fern, classing it now (Jur. Fl. Yorkshire Coast,
1900, p. 161) in the family Polypodiaceae, although in his Wealden Flora, 1894, p. 129,
he placed it in the Schizaeaceae.” [Ward (05) p. 83, note b.] My words are “I am
disposed to regard Sagenopteris as probably a genus of ferns” (loc. cit. 1900, p. 161). I
have never referred this plant to the Polypodiaceae or Schizaeaceae or to any other
family.
[1231] Solms-Laubach (91) A. p. 182.
[1232] I am indebted to my friend Dr Nathorst for calling my attention to Lindman’s
paper.
[1233] For a fuller synonymy, see Seward (00) p. 162.
[1234] Nathorst (042).
[1205] Schenk (71) p. 225.
[1206] Hollick (94) Pl. lxxi.
[1207] Mentioned by Krasser (06) in a preliminary note.
[1208] Frič and Bayer (01) p. 86, fig. 34.
[1209] Heer (82) Pl. xvi.
[1210] Heer (55) A. Vol. iii. p. 156, Pl. cxlv. fig. 35.
[1211] Goebel (05).
[1212] See Seward (94) p. 441, for a description of the floating plants on the lagunas of
Gran Chaco (S. America) by Prof. Graham Kerr.
[1213] Bower (08) p. 611.
[1214] Hollick (94).
[1215] E.g. Lesquereux (78) Pl. lxiv. fig. 14; Pl. v. fig. 10. Staub (87) Pl. xix. fig. 2.
[1216] Zeiller (03) Pl. li. figs. 2, 3.
[1217] Heer (55) A. Vol. iii. p. 156, Pl. cxlv. figs. 1–315.
[1218] Zeiller (092) p. 95.
[1219] Fritel (08).
[1220] See also Arber (06) p. 228.
[1221] Solms-Laubach (91) A. p. 183.
[1222] Dawson (86).
[1223] Zeiller (88) A. p. 58.
[1224] Corda (45) A. Pl. liv.
[1225] Presl, in Sternberg (38) A.
[1226] Schimper (69) A.
[1227] Nathorst (78) p. 17.
[1228] Zigno (56) A. Pl. xx.
[1229] Salfeld (09) p. 17.
[1230] In a footnote to Fontaine’s description of Jurassic plants of Oregon, Lester Ward
writes:—“Seward treats Sagenopteris as a fern, classing it now (Jur. Fl. Yorkshire Coast,
1900, p. 161) in the family Polypodiaceae, although in his Wealden Flora, 1894, p. 129,
he placed it in the Schizaeaceae.” [Ward (05) p. 83, note b.] My words are “I am
disposed to regard Sagenopteris as probably a genus of ferns” (loc. cit. 1900, p. 161). I
have never referred this plant to the Polypodiaceae or Schizaeaceae or to any other
family.
[1231] Solms-Laubach (91) A. p. 182.
[1232] I am indebted to my friend Dr Nathorst for calling my attention to Lindman’s
paper.
[1233] For a fuller synonymy, see Seward (00) p. 162.
[1234] Nathorst (042).
Page 765
[1235] Bunbury (51) A.
[1236] Lindley and Hutton (35) A. Pl. clv.
[1237] Yabe (05) Pl. iii. fig. 16.
[1238] Moeller (02) Pl. vi. fig. 10.
[1239] Lindley and Hutton (33) A. Pl. lxiii. fig. 2.
[1240] Seward (00) p. 169, fig. 26.
[1241] Zigno (56) A. Pl. xxi.
[1242] Moeller (02) Pl. vi. figs. 8, 9.
[1243] Ward (05) Pl. xv. fig. 5.
[1244] Bartholin (92) Pl. v. fig. 9.
[1245] Presl, in Sternberg (38).
[1246] Zigno (56) A. Pls. xxi. xxii.; Raciborski (94) A. Pl. xx. figs. 13–18.
[1247] Brongniart (25) Pl. xii. fig. 1.
[1248] Fontaine, in Ward (05); Salfeld (09) Pl. i.
[1249] Schenk (67) A. Pl. xiii.
[1250] Arber (05) p. 75.
[1251] Seward (942) A. p. 130.
[1252] Velenovský (85) Pl. ii.
[1253] Fontaine, in Ward (05) Pl. lxv. Newberry’s Chiropteris spatulata from Montana
may be founded on leaflets of Sagenopteris Mantelli. Newberry (91).
[1254] Brongniart (28) A. p. 61.
[1255] White (93).
[1256] White (99) p. 143.
[1257] Schimper (69) A. p. 610.
[1258] Sellards (01).
[1259] Weiss, C. E. (69) p. 98, Pl. vi. fig. 13.
[1260] Zeiller (94) p. 169.
[1261] Renault (96) A. p. 1.
[1262] Zeiller (90) Pls. xii. xiii.
[1263] Fontaine and White (80) Pl. xxxiv.
[1264] Fontaine and White (80) Pl. xxxiv. figs. 1–8.
[1265] Sellards (01).
[1266] Grand’Eury (77) A. p. 171.
[1267] Renault and Zeiller (88) A.
[1268] Potonié (93) A. p. 145, Pl. xvii. fig. 3.
[1269] Renault and Zeiller (88) A. p. 282, Pl. xxii. fig. 10.
[1270] Feistmantel (81) A. Pls. xxi. A. xxii. A.
[1236] Lindley and Hutton (35) A. Pl. clv.
[1237] Yabe (05) Pl. iii. fig. 16.
[1238] Moeller (02) Pl. vi. fig. 10.
[1239] Lindley and Hutton (33) A. Pl. lxiii. fig. 2.
[1240] Seward (00) p. 169, fig. 26.
[1241] Zigno (56) A. Pl. xxi.
[1242] Moeller (02) Pl. vi. figs. 8, 9.
[1243] Ward (05) Pl. xv. fig. 5.
[1244] Bartholin (92) Pl. v. fig. 9.
[1245] Presl, in Sternberg (38).
[1246] Zigno (56) A. Pls. xxi. xxii.; Raciborski (94) A. Pl. xx. figs. 13–18.
[1247] Brongniart (25) Pl. xii. fig. 1.
[1248] Fontaine, in Ward (05); Salfeld (09) Pl. i.
[1249] Schenk (67) A. Pl. xiii.
[1250] Arber (05) p. 75.
[1251] Seward (942) A. p. 130.
[1252] Velenovský (85) Pl. ii.
[1253] Fontaine, in Ward (05) Pl. lxv. Newberry’s Chiropteris spatulata from Montana
may be founded on leaflets of Sagenopteris Mantelli. Newberry (91).
[1254] Brongniart (28) A. p. 61.
[1255] White (93).
[1256] White (99) p. 143.
[1257] Schimper (69) A. p. 610.
[1258] Sellards (01).
[1259] Weiss, C. E. (69) p. 98, Pl. vi. fig. 13.
[1260] Zeiller (94) p. 169.
[1261] Renault (96) A. p. 1.
[1262] Zeiller (90) Pls. xii. xiii.
[1263] Fontaine and White (80) Pl. xxxiv.
[1264] Fontaine and White (80) Pl. xxxiv. figs. 1–8.
[1265] Sellards (01).
[1266] Grand’Eury (77) A. p. 171.
[1267] Renault and Zeiller (88) A.
[1268] Potonié (93) A. p. 145, Pl. xvii. fig. 3.
[1269] Renault and Zeiller (88) A. p. 282, Pl. xxii. fig. 10.
[1270] Feistmantel (81) A. Pls. xxi. A. xxii. A.
Page 766
[1271] Oldham and Morris (63) p. 41.
[1272] Schenk (67) A. Pl. xxviii. fig. 12.
[1273] Nathorst (78) Pl. ix.
[1274] Feistmantel (90) A. Pl. xxvii.
[1275] Saporta (73) A. Pls. lxi. lxii.
[1276] Zeiller (02) Pls. x.–xiv. p. 66.
[1277] Zeiller (02) Pl. xi. fig. 4.
[1278] Zeiller (02) Pl. xiii. For synonymy, see also Arber (05) p. 124.
[1279] Seward (04) figs. 18–22.
[1280] Seward (08) p. 98.
[1281] Geinitz (76) Pl. ii. figs. 1–3.
[1282] Nathorst (78) Pl. xix.
[1283] Zeiller (02) Pl. xiv.
[1284] For synonymy and distribution, see Seward (00) pp. 159, 304.
[1285] Schenk (67) A. Pl. xxv. See also Bartholin (92) Pl. ix. fig. 7.
[1286] Etheridge (942).
[1287] Lindley and Hutton (33) A. Pl. xcii.
[1288] Seward (00) p. 14.
[1289] Schenk (71) Pl. xxix.; Seward (942) A. p. 125.
[1290] Stiehler (58) Pls. xii. xiii.
[1291] See p. 576.
[1292] Nathorst (90).
[1293] For figures, see Stiehler loc. cit. and Hosius and Von der Marck (80) Pls. xliii.
xliv.
[1294] For synonymy, see Fontaine, in Ward (99) p. 651; Seward (942) A. p. 114; Seward
(00) p. 20.
[1295] Brongniart (22) A. Pl. ii. fig. 4.
[1296] Brongniart (282) A. Pls. lxii. lxiii.
[1297] Schimper (69) A. p. 645.
[1298] Seward (972) A. p. 317.
[1299] For figures see Zeiller (96) A.; Zeiller (02), (03); Arber (05); Seward (97) A.
[1300] Arber (052); Seward (072).
[1301] Bunbury (61) Pl. xi.
[1302] Zeiller (96) A.
[1303] Oldham (97); Zeiller (972).
[1304] Seward (97) A. (072); Arber (022) p. 20; Zeiller (96) A. p. 374.
[1305] White (08) p. 535.
[1306] Zeiller (02).
[1272] Schenk (67) A. Pl. xxviii. fig. 12.
[1273] Nathorst (78) Pl. ix.
[1274] Feistmantel (90) A. Pl. xxvii.
[1275] Saporta (73) A. Pls. lxi. lxii.
[1276] Zeiller (02) Pls. x.–xiv. p. 66.
[1277] Zeiller (02) Pl. xi. fig. 4.
[1278] Zeiller (02) Pl. xiii. For synonymy, see also Arber (05) p. 124.
[1279] Seward (04) figs. 18–22.
[1280] Seward (08) p. 98.
[1281] Geinitz (76) Pl. ii. figs. 1–3.
[1282] Nathorst (78) Pl. xix.
[1283] Zeiller (02) Pl. xiv.
[1284] For synonymy and distribution, see Seward (00) pp. 159, 304.
[1285] Schenk (67) A. Pl. xxv. See also Bartholin (92) Pl. ix. fig. 7.
[1286] Etheridge (942).
[1287] Lindley and Hutton (33) A. Pl. xcii.
[1288] Seward (00) p. 14.
[1289] Schenk (71) Pl. xxix.; Seward (942) A. p. 125.
[1290] Stiehler (58) Pls. xii. xiii.
[1291] See p. 576.
[1292] Nathorst (90).
[1293] For figures, see Stiehler loc. cit. and Hosius and Von der Marck (80) Pls. xliii.
xliv.
[1294] For synonymy, see Fontaine, in Ward (99) p. 651; Seward (942) A. p. 114; Seward
(00) p. 20.
[1295] Brongniart (22) A. Pl. ii. fig. 4.
[1296] Brongniart (282) A. Pls. lxii. lxiii.
[1297] Schimper (69) A. p. 645.
[1298] Seward (972) A. p. 317.
[1299] For figures see Zeiller (96) A.; Zeiller (02), (03); Arber (05); Seward (97) A.
[1300] Arber (052); Seward (072).
[1301] Bunbury (61) Pl. xi.
[1302] Zeiller (96) A.
[1303] Oldham (97); Zeiller (972).
[1304] Seward (97) A. (072); Arber (022) p. 20; Zeiller (96) A. p. 374.
[1305] White (08) p. 535.
[1306] Zeiller (02).
Page 767
[1307] Potonié (00).
[1308] Seward (043); Zeiller (973); Arber (05) p. 17; D. White (07).
[1309] Amalitzky (01); Zeiller (982).
[1310] Zeiller (02).
[1311] D. White (07) p. 617 (footnote 2).
[1312] For synonymy, see Arber (05) p. 48.
[1313] Zeiller (96) A.
[1314] McCoy (47).
[1315] Zeiller (96) A.
[1316] Arber (05); (052).
[1317] Seward (97) A; (07).
[1318] Royle (33).
[1319] Zeiller (96) A.
[1320] Zeiller (96) A.
[1321] Oldham (97).
[1322] Zeiller (02).
[1323] Zeiller (02) Pl. v. fig. 7.
[1324] Etheridge (94).
[1325] Arber (05) p. 47.
[1326] Zeiller (96) A. p. 368, fig. 13.
[1327] Zeiller (02); (03).
[1328] Oldham (97).
[1329] Amalitzky (01).
[1330] Zeiller (03) Pl. xvi.
[1331] Zeiller (02).
[1332] Seward and Leslie (08) p. 113.
[1333] Dawson (71) A. Pl. xvii.; Fontaine and White (80) p. 11; White (95) p. 315; Arber
(053) p. 307, Pl. xx.
[1334] Jack and Etheridge (92).
[1335] Lesquereux (79) A. Pl. xxv.; Renault and Zeiller (88) A. Pl. xxiii. See p. 517.
[1336] Etheridge (99).
[1337] Feistmantel (80) Pls. xxviii. A., xli. A.
[1338] Seward (07).
[1339] McCoy (47).
[1340] Arber (022).
[1341] McCoy (60) p. 107 (footnote).
[1342] McCoy (75).
[1308] Seward (043); Zeiller (973); Arber (05) p. 17; D. White (07).
[1309] Amalitzky (01); Zeiller (982).
[1310] Zeiller (02).
[1311] D. White (07) p. 617 (footnote 2).
[1312] For synonymy, see Arber (05) p. 48.
[1313] Zeiller (96) A.
[1314] McCoy (47).
[1315] Zeiller (96) A.
[1316] Arber (05); (052).
[1317] Seward (97) A; (07).
[1318] Royle (33).
[1319] Zeiller (96) A.
[1320] Zeiller (96) A.
[1321] Oldham (97).
[1322] Zeiller (02).
[1323] Zeiller (02) Pl. v. fig. 7.
[1324] Etheridge (94).
[1325] Arber (05) p. 47.
[1326] Zeiller (96) A. p. 368, fig. 13.
[1327] Zeiller (02); (03).
[1328] Oldham (97).
[1329] Amalitzky (01).
[1330] Zeiller (03) Pl. xvi.
[1331] Zeiller (02).
[1332] Seward and Leslie (08) p. 113.
[1333] Dawson (71) A. Pl. xvii.; Fontaine and White (80) p. 11; White (95) p. 315; Arber
(053) p. 307, Pl. xx.
[1334] Jack and Etheridge (92).
[1335] Lesquereux (79) A. Pl. xxv.; Renault and Zeiller (88) A. Pl. xxiii. See p. 517.
[1336] Etheridge (99).
[1337] Feistmantel (80) Pls. xxviii. A., xli. A.
[1338] Seward (07).
[1339] McCoy (47).
[1340] Arber (022).
[1341] McCoy (60) p. 107 (footnote).
[1342] McCoy (75).
Page 768
[1343] Feistmantel (79).
[1344] Seward and Woodward (05) p. 2.
[1345] Arber (022) p. 14.
[1346] White, D. (07).
[1347] Arber (05).
[1348] Carruthers (692) p. 9, Pl. vi. fig. 1.
[1349] Seward (03) p. 83.
[1350] Hayden (07); Seward (075).
[1351] Darwin (87) A. Vol. iii. p. 248.
[1352] For synonymy, see Arber (05) p. 104.
[1353] Seward and Smith Woodward (05); (075).
[1354] White (08) pp. 473, 483.
[1355] Stur (84) p. 638
[1356] White (08) p. 537, Pl. viii. figs. 8–10.
[1357] Ibid. p. 543, Pl. ix. figs. 1–3.
[1358] Feistmantel (80) Pl. xxvii. fig. 5.
[1359] Lesquereux (80) A. p. 142; Pl. xxv.
[1360] Brongniart (28) A. p. 129.
[1361] Grand’Eury (90) A. Pl. viii. fig. 5.
[1362] Zeiller (90) p. 166, Pl. xiii. fig. 2.
[1363] Renault and Zeiller (88) A. Pl. xxiii. fig. 6.
[1364] Lesquereux, loc. cit.
[1365] White (052) p. 381.
[1366] Grand’Eury (90) A. p. 305.
[1367] Schimper and Mougeot (44) A.
[1368] Schimper (69) A. p. 447.
[1369] Carruthers (692).
[1370] See Arber (05) p. 116; Seward (03) p. 85.
[1371] White (08) p. 483.
[1372] Seward (03) p. 83.
[1373] Zeiller (95) p. 616.
[1374] Feistmantel (79).
[1375] Kurtz (94).
[1376] Schimper and Mougeot (44) A. Pl. xxxviii.
[1377] Blanckenhorn (85) p. 127, Pls. xvii.–xix.
[1378] Vol. i. p. 292.
[1379] Zeiller (002).
[1344] Seward and Woodward (05) p. 2.
[1345] Arber (022) p. 14.
[1346] White, D. (07).
[1347] Arber (05).
[1348] Carruthers (692) p. 9, Pl. vi. fig. 1.
[1349] Seward (03) p. 83.
[1350] Hayden (07); Seward (075).
[1351] Darwin (87) A. Vol. iii. p. 248.
[1352] For synonymy, see Arber (05) p. 104.
[1353] Seward and Smith Woodward (05); (075).
[1354] White (08) pp. 473, 483.
[1355] Stur (84) p. 638
[1356] White (08) p. 537, Pl. viii. figs. 8–10.
[1357] Ibid. p. 543, Pl. ix. figs. 1–3.
[1358] Feistmantel (80) Pl. xxvii. fig. 5.
[1359] Lesquereux (80) A. p. 142; Pl. xxv.
[1360] Brongniart (28) A. p. 129.
[1361] Grand’Eury (90) A. Pl. viii. fig. 5.
[1362] Zeiller (90) p. 166, Pl. xiii. fig. 2.
[1363] Renault and Zeiller (88) A. Pl. xxiii. fig. 6.
[1364] Lesquereux, loc. cit.
[1365] White (052) p. 381.
[1366] Grand’Eury (90) A. p. 305.
[1367] Schimper and Mougeot (44) A.
[1368] Schimper (69) A. p. 447.
[1369] Carruthers (692).
[1370] See Arber (05) p. 116; Seward (03) p. 85.
[1371] White (08) p. 483.
[1372] Seward (03) p. 83.
[1373] Zeiller (95) p. 616.
[1374] Feistmantel (79).
[1375] Kurtz (94).
[1376] Schimper and Mougeot (44) A. Pl. xxxviii.
[1377] Blanckenhorn (85) p. 127, Pls. xvii.–xix.
[1378] Vol. i. p. 292.
[1379] Zeiller (002).
Page 769
[1380] Blanckenhorn (85) p. 129, Pl. xxi.
[1381] Blanckenhorn loc. cit. The specimens figured by this author are in the Strassburg
Museum, as are also some of those figured by Schimper and Mougeot.
[1382] Schimper (69) A. p. 452.
[1383] Schimper and Koechlin-Schlumberger (62) A.
[1384] Ibid.
[1385] Fritsch, K. (97).
[1386] Stur (75) A. Pl. xiv. fig. 1.
[1387] Grigoriew (98) Pl. iv.
[1388] Schuster (08) p. 184.
[1389] Presl, in Sternberg (38) A.
[1390] For synonymy, see Zeiller (88) A. p. 301.
[1391] page 406.
[1392] Potonié (03) p. 162.
[1393] Zeiller (06) Pls. vi. vii.
[1394] Arber (06).
[1395] Renault and Zeiller (88) A.; Zeiller (88) A. Pl. li.
[1396] Renault and Zeiller (88) A. Pl. xxiv.
[1397] Grand’Eury (90) A. Pl. xix.
[1398] Kidston (91) Pl. xxxv.
[1399] Goebel (05) p. 318.
[1400] See p. 406, fig. 293; Potonié (03) also figures a young frond of Dactylotheca
plumosa partially covered by Aphlebiae.
[1401] Seward (00) Pl. xxi. fig. 1.
[1402] Ibid. p. 145.
[1403] Raciborski (94) A. Pl. xi.
[1404] Brongniart (22) A.
[1405] For synonymy, see Kidston (86) p. 68.
[1406] Kidston (94) p. 298.
[1407] Zeiller (88) A. p. 147, Pls. iv. v.; Kidston (86) p. 80.
[1408] See p. 535.
[1409] Lindley and Hutton (31) A. Pl. xlv.
[1410] Peach (78).
[1411] Kidston (87) p. 145.
[1412] This species will be described in Vol. iii.
[1413] Benson (04).
[1414] Miller (57), Frontispiece.
[1415] Scott (052) p. 144.
[1381] Blanckenhorn loc. cit. The specimens figured by this author are in the Strassburg
Museum, as are also some of those figured by Schimper and Mougeot.
[1382] Schimper (69) A. p. 452.
[1383] Schimper and Koechlin-Schlumberger (62) A.
[1384] Ibid.
[1385] Fritsch, K. (97).
[1386] Stur (75) A. Pl. xiv. fig. 1.
[1387] Grigoriew (98) Pl. iv.
[1388] Schuster (08) p. 184.
[1389] Presl, in Sternberg (38) A.
[1390] For synonymy, see Zeiller (88) A. p. 301.
[1391] page 406.
[1392] Potonié (03) p. 162.
[1393] Zeiller (06) Pls. vi. vii.
[1394] Arber (06).
[1395] Renault and Zeiller (88) A.; Zeiller (88) A. Pl. li.
[1396] Renault and Zeiller (88) A. Pl. xxiv.
[1397] Grand’Eury (90) A. Pl. xix.
[1398] Kidston (91) Pl. xxxv.
[1399] Goebel (05) p. 318.
[1400] See p. 406, fig. 293; Potonié (03) also figures a young frond of Dactylotheca
plumosa partially covered by Aphlebiae.
[1401] Seward (00) Pl. xxi. fig. 1.
[1402] Ibid. p. 145.
[1403] Raciborski (94) A. Pl. xi.
[1404] Brongniart (22) A.
[1405] For synonymy, see Kidston (86) p. 68.
[1406] Kidston (94) p. 298.
[1407] Zeiller (88) A. p. 147, Pls. iv. v.; Kidston (86) p. 80.
[1408] See p. 535.
[1409] Lindley and Hutton (31) A. Pl. xlv.
[1410] Peach (78).
[1411] Kidston (87) p. 145.
[1412] This species will be described in Vol. iii.
[1413] Benson (04).
[1414] Miller (57), Frontispiece.
[1415] Scott (052) p. 144.
Page 770
[1416] Grand’Eury (052).
[1417] Kidston (012) p. 191.
[1418] Potonié (95); (99).
[1419] Zeiller (792).
[1420] Kidston (012) p. 195.
[1421] For synonymy, see Kidston (03) p. 771.
[1422] Grand’Eury (08).
[1423] Stur (75) A. p. 120.
[1424] Zeiller (792); (88) A. p. 142.
[1425] Kidston (94) p. 240.
[1426] Zeiller (88) A. p. 147.
[1427] Ibid. Pl. xvi.
[1428] Potonié (92).
[1429] Nathorst (02) p. 15.
[1430] Crépin (75). Previously described by Crépin (74) as Psilophyton.
[1431] Gilkinet (75).
[1432] Nathorst (02).
[1433] Zeiller (092) p. 20.
[1434] Ettingshausen (52).
[1435] Sellards (00).
[1436] For synonymy, see Seward (03) p. 52.
[1437] Solms-Laubach and Steinmann (99) Pl. xiv. fig. 2; Szajnocha (88).
[1438] Geinitz (76) Pl. i.
[1439] Seward (08) p. 95.
[1440] Feistmantel (90) A. Pl. xxiv.
[1441] Zeiller (03).
[1442] For references, see Seward (04) p. 31.
[1443] Berry (03).
[1444] Seward (04) p. 31.
[1445] Hollick and Jeffrey (09) p. 24.
[1446] Raciborski (94) A. Pl. xx. figs. 1, 2; Zeiller (002) p. 98.
[1447] v. 5950.
[1448] Fontaine (89) Pls. xvii. xviii.
[1449] Solms-Laubach (91) A. p. 141.
[1450] Schimper (69) A. p. 472.
[1451] Kurr (45) Pl. ii. fig. 1.
[1452] Seward (04) p. 30.
[1417] Kidston (012) p. 191.
[1418] Potonié (95); (99).
[1419] Zeiller (792).
[1420] Kidston (012) p. 195.
[1421] For synonymy, see Kidston (03) p. 771.
[1422] Grand’Eury (08).
[1423] Stur (75) A. p. 120.
[1424] Zeiller (792); (88) A. p. 142.
[1425] Kidston (94) p. 240.
[1426] Zeiller (88) A. p. 147.
[1427] Ibid. Pl. xvi.
[1428] Potonié (92).
[1429] Nathorst (02) p. 15.
[1430] Crépin (75). Previously described by Crépin (74) as Psilophyton.
[1431] Gilkinet (75).
[1432] Nathorst (02).
[1433] Zeiller (092) p. 20.
[1434] Ettingshausen (52).
[1435] Sellards (00).
[1436] For synonymy, see Seward (03) p. 52.
[1437] Solms-Laubach and Steinmann (99) Pl. xiv. fig. 2; Szajnocha (88).
[1438] Geinitz (76) Pl. i.
[1439] Seward (08) p. 95.
[1440] Feistmantel (90) A. Pl. xxiv.
[1441] Zeiller (03).
[1442] For references, see Seward (04) p. 31.
[1443] Berry (03).
[1444] Seward (04) p. 31.
[1445] Hollick and Jeffrey (09) p. 24.
[1446] Raciborski (94) A. Pl. xx. figs. 1, 2; Zeiller (002) p. 98.
[1447] v. 5950.
[1448] Fontaine (89) Pls. xvii. xviii.
[1449] Solms-Laubach (91) A. p. 141.
[1450] Schimper (69) A. p. 472.
[1451] Kurr (45) Pl. ii. fig. 1.
[1452] Seward (04) p. 30.
Page 771
[1453] Saporta (73) A.
[1454] Schenk (67) A.
[1455] Salfeld (07) p. 192.
[1456] Seward (04) p. 34, fig. 2, Pl. iv.
[1457] Salfeld (09).
[1458] Schenk (76) Pl. xxvi. fig. 7.
[1459] Salfeld (09) p. 34.
[1460] Zigno (56) A.
[1461] Solms-Laubach (91) A. p. 114.
[1462] Nathorst (78).
[1463] Saporta (73) A. p. 352.
[1464] Nathorst (78) p. 122.
[1465] Zeiller (03) p. 52.
[1466] Leckenby (64) A. Pl. x. fig. 1; Seward (04) p. 36.
[1467] Schenk (87).
[1468] Zeiller (03) Pls. vi.–viii.
[1469] Zigno (56) A. Pls. xii. xiii.
[1470] Seward (00) p. 170.
[1471] Brongniart (28) A. p. 49.
[1472] Seward (00) p. 171.
[1473] Saporta (73) A. p. 368.
[1474] Krasser (95).
[1475] Saporta (73) A. Pl. xlvii.
[1476] Brongniart (28) A. p. 60.
[1477] Kidston (012) p. 196.
[1478] Potonié (93) A. Pl. xv.
[1479] Kidston (89) p. 409.
[1480] Zeiller (06) Pls. xix.–xxii.; (002) p. 100, fig. 73.
[1481] Weiss, C. E. (70).
[1482] Zeiller (06) p. 90.
[1483] Lesquereux (80) A. p. 131; Weiss (70).
[1484] Weiss (69) p. 37.
[1485] Grand’Eury (77) A. Pl. A.
[1486] Renault and Zeiller (88) A. p. 219.
[1487] Stur (84).
[1488] Grand’Eury (77) A. Pl. xiii.
[1489] Grand’Eury (08).
[1454] Schenk (67) A.
[1455] Salfeld (07) p. 192.
[1456] Seward (04) p. 34, fig. 2, Pl. iv.
[1457] Salfeld (09).
[1458] Schenk (76) Pl. xxvi. fig. 7.
[1459] Salfeld (09) p. 34.
[1460] Zigno (56) A.
[1461] Solms-Laubach (91) A. p. 114.
[1462] Nathorst (78).
[1463] Saporta (73) A. p. 352.
[1464] Nathorst (78) p. 122.
[1465] Zeiller (03) p. 52.
[1466] Leckenby (64) A. Pl. x. fig. 1; Seward (04) p. 36.
[1467] Schenk (87).
[1468] Zeiller (03) Pls. vi.–viii.
[1469] Zigno (56) A. Pls. xii. xiii.
[1470] Seward (00) p. 170.
[1471] Brongniart (28) A. p. 49.
[1472] Seward (00) p. 171.
[1473] Saporta (73) A. p. 368.
[1474] Krasser (95).
[1475] Saporta (73) A. Pl. xlvii.
[1476] Brongniart (28) A. p. 60.
[1477] Kidston (012) p. 196.
[1478] Potonié (93) A. Pl. xv.
[1479] Kidston (89) p. 409.
[1480] Zeiller (06) Pls. xix.–xxii.; (002) p. 100, fig. 73.
[1481] Weiss, C. E. (70).
[1482] Zeiller (06) p. 90.
[1483] Lesquereux (80) A. p. 131; Weiss (70).
[1484] Weiss (69) p. 37.
[1485] Grand’Eury (77) A. Pl. A.
[1486] Renault and Zeiller (88) A. p. 219.
[1487] Stur (84).
[1488] Grand’Eury (77) A. Pl. xiii.
[1489] Grand’Eury (08).
Page 772
[1490] Renault and Zeiller (88) A. Pl. xxiv.
[1491] Weiss, C. E. (69); Goeppert (64) A.; Potonié (93) A, (04); Lesquereux (80) A., p.
124; White (99) p. 125.
[1492] Seward (08) p. 97, Pl. viii.
[1493] Brongniart, in Murchison, Verneuil, and Keyserling (45) Pl. A.
[1494] Weiss, C. E. (70) p. 871.
[1495] Brongniart (49) A. p. 24.
[1496] Grand’Eury (06).
[1497] Weiss (69) Pls. vi. vii.
[1498] Potonié (93) A. Pl. i. figs. 1, 2.
[1499] Weber and Sterzel (96) p. 99.
[1500] Zeiller (90) p. 84.
[1501] Zeiller (983).
[1502] For figures of this and other species, see Potonié (07).
[1503] For synonymy, see Zeiller (90) p. 87 and Potonié (07) p. 2.
[1504] Schuster (08) Pl. viii. fig. 7.
[1505] Weiss, C. E. (70).
[1506] Schlotheim (20) A. p. 406.
[1507] Renault and Zeiller (88) A. Pl. XIX.
[1508] White (052) p. 388.
[1509] Forbes (53) p. 43.
[1510] Baily (59) p. 75.
[1511] Schimper (69) A. p. 473.
[1512] Dawson (71) A. p. 48; (82).
[1513] Kidston (912) p. 30, Pl. iii.; (06) p. 434.
[1514] Baily (75) Pl. xxviii.
[1515] Carruthers (722) Pl. ii.
[1516] Dawson (71) A.
[1517] Smith and White (05) p. 39.
[1518] Lesquereux (80) A.
[1519] Crépin (74).
[1520] Nathorst (02).
[1521] Schmalhausen (94).
[1522] Nathorst (04).
[1523] Krasser (00) Pl. i. figs. 3–7.
[1524] Zeiller (032) p. 27.
[1525] Stur (75) A. Pls. viii. xii. xvi.
[1491] Weiss, C. E. (69); Goeppert (64) A.; Potonié (93) A, (04); Lesquereux (80) A., p.
124; White (99) p. 125.
[1492] Seward (08) p. 97, Pl. viii.
[1493] Brongniart, in Murchison, Verneuil, and Keyserling (45) Pl. A.
[1494] Weiss, C. E. (70) p. 871.
[1495] Brongniart (49) A. p. 24.
[1496] Grand’Eury (06).
[1497] Weiss (69) Pls. vi. vii.
[1498] Potonié (93) A. Pl. i. figs. 1, 2.
[1499] Weber and Sterzel (96) p. 99.
[1500] Zeiller (90) p. 84.
[1501] Zeiller (983).
[1502] For figures of this and other species, see Potonié (07).
[1503] For synonymy, see Zeiller (90) p. 87 and Potonié (07) p. 2.
[1504] Schuster (08) Pl. viii. fig. 7.
[1505] Weiss, C. E. (70).
[1506] Schlotheim (20) A. p. 406.
[1507] Renault and Zeiller (88) A. Pl. XIX.
[1508] White (052) p. 388.
[1509] Forbes (53) p. 43.
[1510] Baily (59) p. 75.
[1511] Schimper (69) A. p. 473.
[1512] Dawson (71) A. p. 48; (82).
[1513] Kidston (912) p. 30, Pl. iii.; (06) p. 434.
[1514] Baily (75) Pl. xxviii.
[1515] Carruthers (722) Pl. ii.
[1516] Dawson (71) A.
[1517] Smith and White (05) p. 39.
[1518] Lesquereux (80) A.
[1519] Crépin (74).
[1520] Nathorst (02).
[1521] Schmalhausen (94).
[1522] Nathorst (04).
[1523] Krasser (00) Pl. i. figs. 3–7.
[1524] Zeiller (032) p. 27.
[1525] Stur (75) A. Pls. viii. xii. xvi.
Page 773
[1526] Kidston (882).
[1527] Grand’Eury (08).
[1528] Brongniart (22) A.
[1529] Kidston (052).
[1530] Renault (76).
[1531] Grand’Eury (08).
[1532] White (99) p. 128.
[1533] Grand’Eury (77) A. p. 122.
[1534] Zeiller (90) Pl. xi. fig. 6.
[1535] Potonié (99) p. 113.
[1536] Renault (82) A. Vol. iii.; Zeiller (90) p. 139.
[1537] Grand’Eury (77) A. p. 105.
[1538] Brongniart (22) A. Pl. ii. fig. 6. For synonymy, see Kidston (03) p. 773; Zeiller
(88) A. p. 261.
[1539] For synonymy, see Kidston (88) p. 354.
[1540] Scheuchzer (1723) A. p. 129, Pl. x. fig. 3.
[1541] Lhywd (1760) A. Pl. v. fig. 190.
[1542] Lesquereux (79) A. Pl. viii.
[1543] Fontaine and White (80) p. 47.
[1544] Bunbury (47) Pl. xxi.
[1545] Kidston (94) p. 357; (03) p. 806.
[1546] White (99) p. 132.
[1547] Zeiller (88) A. p. 251.
[1548] See Vol. i. p. 45.
[1549] Zalessky (07) Pl. xxiv. fig. 5.
[1550] Zeiller (88) A. p. 251.
[1551] Renault and Zeiller (88) A. p. 251, Pl. xxxii.
[1552] Brongniart (28) A. p. 51.
[1553] Lindley and Hutton (33) A. p. 28.
[1554] Lesquereux (66) A.
[1555] Roehl (69).
[1556] Seward (88).
[1557] Potonié (99) p. 153 (note).
[1558] Gutbier (35).
[1559] Presl, in Sternberg (38) A.
[1560] Grand’Eury (04).
[1561] Zeiller (90) Pl. xi. fig. 9.
[1527] Grand’Eury (08).
[1528] Brongniart (22) A.
[1529] Kidston (052).
[1530] Renault (76).
[1531] Grand’Eury (08).
[1532] White (99) p. 128.
[1533] Grand’Eury (77) A. p. 122.
[1534] Zeiller (90) Pl. xi. fig. 6.
[1535] Potonié (99) p. 113.
[1536] Renault (82) A. Vol. iii.; Zeiller (90) p. 139.
[1537] Grand’Eury (77) A. p. 105.
[1538] Brongniart (22) A. Pl. ii. fig. 6. For synonymy, see Kidston (03) p. 773; Zeiller
(88) A. p. 261.
[1539] For synonymy, see Kidston (88) p. 354.
[1540] Scheuchzer (1723) A. p. 129, Pl. x. fig. 3.
[1541] Lhywd (1760) A. Pl. v. fig. 190.
[1542] Lesquereux (79) A. Pl. viii.
[1543] Fontaine and White (80) p. 47.
[1544] Bunbury (47) Pl. xxi.
[1545] Kidston (94) p. 357; (03) p. 806.
[1546] White (99) p. 132.
[1547] Zeiller (88) A. p. 251.
[1548] See Vol. i. p. 45.
[1549] Zalessky (07) Pl. xxiv. fig. 5.
[1550] Zeiller (88) A. p. 251.
[1551] Renault and Zeiller (88) A. p. 251, Pl. xxxii.
[1552] Brongniart (28) A. p. 51.
[1553] Lindley and Hutton (33) A. p. 28.
[1554] Lesquereux (66) A.
[1555] Roehl (69).
[1556] Seward (88).
[1557] Potonié (99) p. 153 (note).
[1558] Gutbier (35).
[1559] Presl, in Sternberg (38) A.
[1560] Grand’Eury (04).
[1561] Zeiller (90) Pl. xi. fig. 9.
Page 774
[1562] Zeiller (99) p. 46.
[1563] Bunbury (47) A. p. 427.
[1564] Lyell (45) A. Vol. ii. p. 202.
[1565] Lesquereux (80) A. p. 146.
[1566] Sternberg (26) A.
[1567] Grand’Eury (04).
[1568] Grand’Eury (90) A.
[1569] Zeiller (90) Pl. ix. fig. 6, A.
[1570] Stur (83).
[1571] Scott (07) p. 206; Scott and Maslen (06) p. 112.
[1572] Grand’Eury (04).
[1573] For synonymy, see Kidston (03) p. 772: Zeiller (88) A.
[1574] Scheuchzer (1723) A. Pl. i. fig. 4.
[1575] Kidston (94) p. 245.
[1576] For synonymy, see Kidston (94) p. 596; (03) p. 806; White (99) p. 117.
[1577] Grand’Eury (04).
[1578] Kidston (94) p. 245.
[1579] Brongniart (28) A. p. 59.
[1580] page 494.
[1581] Kidston (94) p. 596.
[1582] Grand’Eury (05).
[1583] Potonié (922); (93) p. 54.
[1584] For synonymy, see Kidston (88) p. 366.
[1585] Zeiller (90) p. 45; Potonié (93) A. p. 57.
[1586] Germar (44) Pls. xxxv. xxxvi.
[1587] Kidston (88) p. 366.
[1588] Stur (83).
[1589] Renault and Zeiller (88) A. p. 196.
[1590] Potonié (93) A. p. 48.
[1591] Zeiller (002) p. 88.
[1592] page 397.
[1593] Renault and Zeiller (88) A. p. 178, Pls. v.–viii. Ante, p. 419.
[1594] Potonié (02).
[1595] Schimper (69) A. p. 688.
[1563] Bunbury (47) A. p. 427.
[1564] Lyell (45) A. Vol. ii. p. 202.
[1565] Lesquereux (80) A. p. 146.
[1566] Sternberg (26) A.
[1567] Grand’Eury (04).
[1568] Grand’Eury (90) A.
[1569] Zeiller (90) Pl. ix. fig. 6, A.
[1570] Stur (83).
[1571] Scott (07) p. 206; Scott and Maslen (06) p. 112.
[1572] Grand’Eury (04).
[1573] For synonymy, see Kidston (03) p. 772: Zeiller (88) A.
[1574] Scheuchzer (1723) A. Pl. i. fig. 4.
[1575] Kidston (94) p. 245.
[1576] For synonymy, see Kidston (94) p. 596; (03) p. 806; White (99) p. 117.
[1577] Grand’Eury (04).
[1578] Kidston (94) p. 245.
[1579] Brongniart (28) A. p. 59.
[1580] page 494.
[1581] Kidston (94) p. 596.
[1582] Grand’Eury (05).
[1583] Potonié (922); (93) p. 54.
[1584] For synonymy, see Kidston (88) p. 366.
[1585] Zeiller (90) p. 45; Potonié (93) A. p. 57.
[1586] Germar (44) Pls. xxxv. xxxvi.
[1587] Kidston (88) p. 366.
[1588] Stur (83).
[1589] Renault and Zeiller (88) A. p. 196.
[1590] Potonié (93) A. p. 48.
[1591] Zeiller (002) p. 88.
[1592] page 397.
[1593] Renault and Zeiller (88) A. p. 178, Pls. v.–viii. Ante, p. 419.
[1594] Potonié (02).
[1595] Schimper (69) A. p. 688.
Page 775
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