THE EUSPORANGIATAE

THE COMPARATIVE MORPHOLOGY
OF THE OPHIOGLOSSACEAE
AND MARATTIACEAE

BY

DOUGLAS HOUGHTON CAMPBELL

PROFESSOR OF BOTANY, LELAND STANFORD JUNIOR UNIVERSITY

WASHINGTON, D. C.
Published by the Carnegie Institution of Washington
IQII

CARNEGIE INSTITUTION OF WASHINGTON

Pustication No. 140

Copies of this Book
were first issued

AUG 29 1911

a em ee

PRESS OF ISAAC H. BLANCHARD COMPANY i
NEW YORK

PREFACE.

The great importance of the eusporangiate ferns as the nearest existing rela-
tives of the Paleozoic ancestors of the higher types of flowering plants invests
them with an especial interest for the student of plant evolution; and no apology
is necessary for presenting at length a summary of our present knowledge of the
structure and development of these important plants.

For more than twenty years the writer has been much interested in the study
of the Eusporangiate and during this time has published a number of works deal-
ing with them. He has had rather unusual opportunities for collecting these forms,
and an extensive and representative collection of materials comprising a good many
species has been accumulated, so that the time seemed ripe for a comparative study
of the group, for the purpose of determining, as far as might be, the relationships
existing between the different genera, as well as for throwing some light upon the
question of their position in the great series of ferns.

The present memoir is an attempt to present the results of these studies, based
mainly upon the writer’s own materials, but supplemented by a careful study of
the work of other investigators who have described the structure and development
of the Eusporangiate.

The writer’s grateful acknowledgments are due to a number of colleagues who
have rendered assistance in various ways. Especially is he indebted to Prof. E. C.
Jeffrey, through whose kindness a large number of admirably preserved prothallia
and young plants of Botrychium virginianum were sent the writer, and in addition
a number of valuable slides of the same. Without this material the work on Bo-
trychium would have been very incomplete.

To my colleague in Stanford University, Prof. L. L. Burlingame, thanks are
due for valuable assistance in the preparation of the photographic plates, as well as
for the use of a number of important slides of Ophioglossum and Helminthostachys.

To Prof. J. C. Willis, of the- Botanic Gardens at Peradeniya, the writer would
express his appreciation of many kindnesses and assistance in collecting during his
stay in Ceylon.

It was the good fortune of the writer to enjoy the unequaled facilities for
collecting material offered by the great gardens at Buitenzorg and Tjibodas in Java,
where, through the interest and courtesy of the distinguished director, Professor
M. Treub, whose recent death was such an irreparable loss to science, means were
afforded for securing the most valuable materials used in the preparation of the
present work.

Douctas Houcuton CamPBELL.

STANFORD University, April, 1gto.

iii

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TABLE OF CONTENTS.

PREFACE

INTRODUCTION

Part |. THE OPpHIOGLOSSALES

I. THe GAMETOPHYTE :
Germination in Ophioglossum .

The Adult Gametophyte of Ophioglossurs

The Histology of the Gametophyte .
The Gametophyte of Botrychium :

The Histology of the Gametophyte of Botr ‘ye hun
The Gametophyte of He Iminthostachys . A 3
The Endophyte . Z
The Sexual Organs

The Antheridium. .

The Antheridium of Ophiealossura .

The Antheridium of Botr ychium ;

The Antheridium of une :

Spermatogenesis . ,

The Archegonium

The Archegonium of Ophioelossune

The Archegonium of Botrychium
Fertilization . ;

Fertilization in Botrychium virginianum.
Significance of the Endophy te.

Il. THe Emsryo
The Embryo of Oph ctosan: :

The Development of the Primary Bud in (Onno Pabaacapte

The Embryo of Ophioglossum vulgatum :

The Anatomy of the Young PROP, of Ophiogloscum :
The Embryo of Botrychium A
The Embryo of He Iminthostach iy Sins

Ill. THe Younc SporopHyTE :
The Young Sporophyte of Ophislecam
The Young Sporophyte of Botrychium .
The Young Sporophyte of Helminthostachys. :
Comparison of the Young Sporophytes of the Opielenscee e

IV. Tue Aputt SporopuyTe .

The Sporophyte of Ophroglossum
The Anatomy of Euophtoglossum.
The Root in ‘Euophioglossum ;
Anatomy of Ophioderma .
Anatomy of Chetroglossa.

The Sporophy te of Botrychium

The Sporophyte of He Iminthostach ys ;

The Sporangiophore of the Ophioglossales :
The Development of the Sporangiophore
The Development of the Sporangium

- 34-54

vi CONTENTS

Part Il. THe Maratriaces.

I. Tum GameTorpnyYTEe «s)he me KOK Se.
The Prothallium of Kauwlfussia. 2. 6 6 6 6 4 ee ek 122
The Prothallium of Danaea. ee Me So wees
The Endophyte of the Marattiacexz re
The Sexual'Organs . 0. se) ey |) SD ee
The Antheridium =. ee
Spermatogetiesis. 9. 6 + ee me
The Archegonium 5. + =. es a
Fertilization +. lee ist Wes) oe i wr ok ee
Il. Tue Emprvo.. Pe oe gee aL ae ee ie et
The Embryo of Poratia: Se a ee kd RM, Eee ea) aS 136
he Embreab tueiwplerie oc ee st ey ve re’ UK ck me RS
ihe Miibyointe eupeRta. Ye. Os! ke Os Se Ie eh eee ys pe LRT
The Embryo of Danaea... iA Met es ate AD
The Anatomy and Histology of the Young Sporophyt Od oe FS eG
The Cotyledon . 5) ee Ce eR oe) ay rh RAD
The Stem of the Young Sporophyte Peano Ee
The Root . . a ee en ee re ef ee eI
The Second Leaf ete ee eee ets prec’ ben Goes + 156
III. Te Ouver Spororuyte . ie Rp ee PER SOO EDS.
The Development of the Vascular Seats in ‘Pass Pe MT Mr As sae ar ee oe Ne)
‘rhe Aduleisporophyte of Danan, 3). ee ae) ee ee eS
‘The Anatomy.of the;Leaf. <0 3. °c) EG Ee
‘The Apical Growth ofithe ioots. . 9. = ./-., 8s) Bey 0. ee eee es
The Sporophyte of Kaulfussta een Ae PE A ee es mee
The Sporophyte of Marattia . . xe sey RS ek 0 Vr ae ee eS
The Adult Sporophyte of vate. |. ee 193
The Sporophyte of Angiopteris — . 24 kee TL eek ee rn ee eee LOG
The Adult pila di of Angiopteris i we ae ne ee eee
Archangiopteris. . Og nS OO ere
a Macroglossum .. [wee ae Ae ee Be ee ey eee
Tissues of the Marattizees F BS oe ce’ OT ee ee eee oe
The Sporophyll of the Westie. nik. ek 204
The Sporanpium'ofithe Marattiacee . =. = © 3 « te ce = tee 205
Part III.
Tue Oricin AND RELATIONSHIPS OF THE EUSPORANGIATAE . . «© «© + «© + « 209
Conclusion... eS oc ee Or eee gern a chy emery),
BIBLioGRAPHY ee Oe ee ae Bet a Oe ay ge re gee i ae a
Wneror.Puaene 4%, Sm ee ees wm ee es ee ee” Gree
Tepes {ores ee eee fers | ao ech "eee iShares Os a ce es

THE EUSPORANGIATAE

THE COMPARATIVE MORPHOLOGY

OF

THE OPHIOGLOSSACEAE AND MARATTIACEAE

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INTRODUCTION.

It is pretty well agreed among botanists that most of the seed plants, perhaps
all of them, are descendants of some fern-like Paleozoic ancestors. The geological
record is remarkably perfect in many respects, and our knowledge of many of these
Paleozoic fossils is extraordinarily complete. Among the most important con-
tributions made of late years to our knowledge of these Paleozoic fossils is the fact
that many of these Paleozoic “ferns” were really seed-bearing plants intermediate
in character between the true ferns and the more highly developed flowering plants.

At best the fossil record is very incomplete in regard to many extremely impor-
tant structural details, and therefore it is especially necessary that these points
should be thoroughly studied in such of the existing ferns as, for any reason, seem
to be at all closely related to the ancient Paleozoic types.

The name Eusporangiate was proposed by Goebel to include the two very
peculiar families of fern-like plants, the Marattiacee and Ophioglossacee, which
differ in several important respects from the much more numerous and specialized
Leptosporangiate, the predominant ferns of the present day. The Eusporangiate
comprise 100 or more species of widely distributed ferns, of which the Marattiaceze
are mainly tropical in their distribution, while the Ophioglossacez include a good
many species of temperate regions as well. The Eusporangiate are distinguished
primarily by the character of the sporangium, which is always much more massive
than in the typical ferns, the Leptosporangiate. In the latter, the sporangium can
almost always be traced back to a single mother cell which usually arises from the
surface of the leaf, while in the Eusporangiate the sporangium is already multi-
cellular when it is first recognizable.

The Marattiacez are in general appearance much like the typical ferns, and
there is no question of their relationship to the Leptosporangiate. The resem-
blances are less obvious in the case of the Ophioglossacee, and some students of
the ferns have expressed the opinion that the Ophioglossacee should be separated
entirely from the ferns and placed in a distinct class. (See Bower 9.) A careful
comparative study, however, of the two families included in the Eusporangiata shows
so many close correspondences in structure, both of the sporophyte and gameto-
phyte, that their association together is amply justified.

The Marattiacea are known to be very ancient forms, unmistakable members
of this family occurring abundantly in Paleozoic formations. The Ophioglossacez,
on the other hand, are very unsatisfactorily represented in a fossil condition, and
for this reason doubt has been thrown on their antiquity, although their structures
show strong evidences of an extremely primitive character. Certain of the oldest-
known fossil ferns, the Botryopteridex, may possibly prove to be related to the
Ophioglossacez, but the evidence at present is not entirely conclusive.

‘In spite of the unsatisfactory nature of the geological evidence, | am neverthe-
less strongly inclined to believe that the Ophioglossacee, on the whole, represent
the most ancient type among the living ferns, this conclusion being based upon a
very careful study of the structure of both gametophyte and sporophyte.

There are many practical difficulties in the way of studying these interesting
ferns, and these difficulties undoubtedly account for the comparatively small number
of researches that have been made upon their development. A few species, like
Ophioglossum vulgatum and several species of Botrychium, are widespread in their

3

4 INTRODUCTION

range and occur in the temperate regions of Europe and America; but very much
the larger number of these, including all of the Marattiacea, are tropical or sub-
tropical plants and are very seldom seen in cultivation, hence material for their
study must be collected in their natural habitat.

The game tophytes, or sexual plants, are seldom encountered unless very
special search is made for them, and they have been but rarely collected; and even
where the spores can be made to germinate, the long time necessary for the growth
of the gi ametophyte under artificial conditions, and the difficulties of rearing them
to maturity, readily explain the small number of successful attempts to study these

plants under artificial conditions.

As the result of several visits to the tropics of both the Old and New Worlds,
the writer has collected material of all of the eusporangiate genera, except the
recently discovered Archangiopteris from southwestern China and Macroglossum
from Borneo. It has seemed desirable, with this material as a basis, to make a some-
what comprehensive comparative study of the whole group of the Eusporangiate.
In this study, especial attention will be devoted to the structure and development of
the gametophyte and embryo and to the development of the young vegetative organs
of the sporophyte. ‘The general anatomy and histology of the mature sporophyte
have already been pretty satisfactorily studied and described for most of the genera
and a particularly satisfactory account of the development of the sporangium has
been given us in the comprehensive memoirs of Professor Bower (Bower 5, 6), and a
detailed investigation of these points has hardly seemed necessary, although, so far
as possible, the results of the work of previous investigators have been verified.

The writer has already published various papers upon the development of
both the Marattiaceze and Ophioglossacez, and these have been freely drawn upon
in the preparation of the present monograph; but these earlier studies have been
materially extended by further work upon the species previously studied and in-
vestigations have been made upon a number of species which hitherto have not
been examined at all, or have been studied only very incompletely. This is partic-
ularly true of the genus Danaea, which has received comparatively little attention
hitherto. An especially fine lot of material of several species of Danaea was col-
lected in Jamaica in 1908 and an extended study of the gametophyte and young
sporophyte has been made, the complete results of which are now published for
the first time. Attention has also been given to the development of the young
sporophyte in the other eusporangiates, particularly in the peculiar genus Kaul-
fussta, which, like Danaea, has received less attention from the students of these
plants than have the genera Marattia and Angiopterts.

Of late there has been a tendency, especially among students of the fossil ferns,
‘to lay great stress upon the importance of the structure of the vascular skeleton of
the ferns in the study of their phylogeny. It is therefore highly important that a

careful examination a siong be made of the origin and development of the vascular
system in those forms, i. e., the Eusporangiate, which, there is good reason to sup-
pose, are the nearest pa aa “among living plants of the ancient Paleozoic ferns

The results of the writer’s studies on we development of the fibro-vascular
bundles of the sporophyte in all of the eusporangiate ferns have led to some rather
unexpected conclusions as to the real nature of the vascular system in these ferns,
conclusions decidedly at variance with the views generally accepted at present.
‘These results have seemed sufficiently important to warrant a more extended treat-
ment of this subject than was at first contemplated; and this will explain what
might otherwise seem to be a disproportionate amount of space devoted to the origin
and development of the fibro-vascular system in the young sporophyte.

PART. I.. THE -OPHIOGLOSSALES.

The Ophioglossales, the “adder-tongue”’ ferns, include three genera (of which
two are practically cosmopolitan) and embrace numerous species, being sometimes
further divided into several subgenera; the third genus is a monotypic one, confined
to the tropics of the Old World. ‘These three genera are evidently quite closely
related among themselves and may without hesitation be referred to a single family,
the Ophioglossacee. The genus Ophioglossum includes several species of the
temperate regions of the whole world, and some of the species, like O. vulgatum,
are very widespread; the tropical species are much more numerous, but the number
of these is very uncertain and much confusion exists as to the limits of certain species.
The second genus, Botrychium, belongs mainly to the temperate regions, only a
small number of species occurring in the tropics, and these are principally confined
to the cooler mountain regions. ‘The third genus, Helminthostachys, with a single
described species, H. zeylanica, is a not uncommon fern of the lowland forests of
the Indo-Malayan region.

The Ophioglossacez are for the most part quite glabrous plants, of small or
moderate size. The smallest species, like Botrychium simplex and some of the
smaller species of Ophioglossum (e. g., O. californicum, O. bergianum, and some of
the smaller forms of O. moluccanum) may be only 5 or 6 centimeters in height. ‘The
largest species of Botrychium and Helminthostachys sometimes attain a height of
50 centimeters or more, with ample, much-dissected leaves, while the long, ribbon-
like, pendent leaves of the epiphytic Ophioglossum pendulum, the giant of the family,
may reach a length of 1.5 meters.

Except for two species of Ophioglossum belonging to the sections Ophioderma
and Cheiroglossa, the Ophioglossacex are terrestrial plants, usually growing in soil
abounding in humus, and the gametophyte in all cases is a subterranean structure
quite destitute of chlorophyll.

The stem is a rhizome, which is short and upright in the terrestrial species of
Ophioglossum and in Botrychium, but is dorsiventral in Helminthostachys and the
epiphytic species Ophioglossum pendulum. In most of the species of the temperate
regions only a single leaf is developed each year, but there are some exceptions to
this rule in Ophioglossum, especially in the tropical species, where there is no
interruption of the growth.

The leaves are usually ample, and may be quite undivided, as in most species
of Ophioglossum, or they may be dichotomously divided in O. palmatum and some
forms of O. pendulum; or they may be much dissected, usually in a ternate fashion,
in Botrychium and Helminthostachys. The sporangia are sometimes very large,
and are borne upon characteristic spikes, or ‘‘sporangiophores,” whose morpho-
logical nature is a matter of some controversy. The venation of the leaves is
reticulate in all species of Ophioglossum, but in the other genera it resembles that
of the typical ferns.

With the exception of Ophioglossum (Cheiroglossa) palmatum, the sporangio-
phore is normally attached to the adaxial side of the leaf, usually near the junction
of the lamina and petiole; but sometimes it is inserted much lower down, or it

5

6 THE OPHIOGLOSSALES

may arise close to the base of the petiole and appear to be quite independent of
the sterile leaf segment. The sporangia range in number from about half a dozen,
in some of the smaller forms of Botrychium simplex and Ophioglossum, to many
hundred in such large species as Botrychium virgintanum and Helminthostachys.
There is a most interesting series of forms connecting the smaller and simpler types
with the large and complicated ones. With the increasing complexity of the sporan-
giophores, there is usually a reduction in the size of the sporangia, which, however,
become better differentiated than in the simpler types.

There is no question about the close relationships existing between the dif-
ferent genera of the Ophioglossacez, but there is some difference of opinion as to
their connection with other Pteridophytes. While they are probably sufficiently
distinct to be relegated to a special order, Ophioglossales, their peculiarities hardly
warrant separating them entirely from the ferns. As will be seen later, they offer
many points of resemblance to the Marattiales, both in regard to the structure of
the adult sporophyte and that of the gametophyte or sexual plant, and the early
phases of embryonic development. ‘These resemblances are too numerous and too
exact to make it at all likely that the two orders are unrelated.

I. THE GAMETOPHYTE.

The first discovery of the gametophyte of the Ophioglossacee was made by
Hofmeister (Hofmeister 1) who, in 1854, found the gametophyte of Botrychium
lunarta; two years later Mettenius (Mettenius 1) described much more fully the
prothallium of Ophioglossum pedunculosum, which was cultivated in the botanical
garden at Leipzig. No further additions were made to the subject until the writer
(Campbell 4) succeeded in obtaining the first germinating stages of O. pendulum,
collected in the Hawaiian Islands, and those of Botrychtum virginianum; and the
older gametophyte of the latter species was also described. In the year 1898 Jeffrey
(Jeffrey 1) published a complete account of the gametophyte and embryo of Bo-
trychium wvirgintanum. Later contributions to the subject are those of Lang
(Lang 1) on the gametophyte of Ophioglossum pendulum and of Helminthostachys;
and the papers of Bruchmann (Bruchmann J, 2) on the prothallium of Botrychium
lunarta and Ophioglossum vulgatum. In 1905, Lyon (Lyon 1) published a brief
account of the embryo of Botrychium obliquum.

In 1906 I collected in Ceylon a few prothallia of a species of Ophioglossum
which may have been O. reticulatum, and shortly afterward, during a stay in Java,
a number of prothallia of O. moluccanum were found, as well as a few belonging to
an undetermined species associated with the latter. During my stay in Java | was
fortunate enough to obtain also a large number of prothallia of O. pendulum. An
account of these has already been published (Campbell 8).

All species of the Ophioglossaceae that have yet been examined agree in the
underground habit and saprophytic nature of the gametophyte, which always has
associated with it a peculiar endophytic fungus, or “mycorrhiza,” which is un-
doubtedly connected with the assimilation of organic food. Mettenius states that
chlorophyll may be developed if the prothallium appears above ground, and Bruch-
mann found that this was also true in O. vulgatum; but as a rule the prothallium
remains subterranean and quite destitute of chlorophyll.

‘The spores of the Ophioglossacea are always of the tetrahedral type, and when
ripe possess a moderately thick sculptured outer membrane, which is usually colorless
or pale yellow, so that the masses of spores are either white or a pale sulphur-yellow
tint. The ripe spore as a rule is packed with granular matter, which makes the

THE GAMETOPHYTE 7

contents appear opaque and obscures more or less the centrally placed nucleus.
A marked exception to the ordinary type of spore was that found in an undetermined
species of Ophioglossum collected at Buitenzorg in Java. This was supposed to be
O. moluccanum, with which it was growing, but a comparison with typical specimens
of the latter species showed marked differences, the most striking being the spores,
which were larger than in the type, had much less dense contents, and were espe-
cially notable in that they had regularly two nuclei, a condition unique, so far as I
know, among the ferns. (See Campbell 8, fig. 157.) The granular contents of the
spores include numerous albuminous eran: together with more or less starch

and oil.
GERMINATION IN OPHIOGLOSSUM.

The first successful attempts to germinate the spores of Ophioglossum were
made by me in 1892, when ripe spores of the epiphytic O. pendulum were collected
in Hawaii and brought to California. ‘hts species was found in Hawati, growing
usually upon the trunks of tree ferns, and the spores were sown upon bits of the
bark-like masses of roots, which in the commoner tree ferns of Hawaii (species of
Cibotium) cover the trunk with a thick, felted mass. These masses of roots were
kept in jars, and the spores were sown upon them, a good many of them germinating
in course of time. The germination was very slow, the spores often remaining
unchanged for months, and none of these young prothallia developed beyond the
stage with three cells. This failure to develop further was undoubtedly due to the
fact that they did not become infected with the mycorrhiza, which is essential to the
full development of the prothallium.

In 1906 ripe spores of the same species were collected in Ceylon and Java.
In Ceylon spores were secured at the botanical garden in Peradeniya and in the
Barrawa Reserve Forest near Hanwella, where Lang obtained his material. In Java
the spores were mostly collected at Tjibodas. In all of these later experiments the
spores were sown in humus collected from about the base of the spore-bearing
plants. ‘hese masses of wet humus were kept in stoppered bottles.

As in the earlier experiments,
the germination was slow, the first
germinating stages being found only
after a month or more, and in some
cases the spores remained un-
changed fora very long period. The
bottles containing the spores sown
upon the humus were brought back
to California, and a recent exami-
nation (September 1909) showed a
considerable number of apparently
normal spores, as well as living
three-celled prothallia, presumably
the result of comparatively recent
germination. Wes

Spores sown in Tyibodas on Ra A ee EE ES

i
April 18, 1906, were first found Cs Three views of a very young gametophyte of O. pendulum, showing
= = : infection by mycorrhizal fungus. X360.
germinating at Buitenzorg on May Noa :
24, germination at this time being pretty well advanced. OnJune 3 a number of
these had three cells. “The germination (fig. 1) in all cases corresponded closely with
the writer’s former observations and closely resembles that which we shall see pres-
ently in Ophioglossum moluccanum. In no case could any chlorophyll be detected,

alu. le

5 THE OPHIOGLOSSALES

and apparently the prothallium of O. pendulum is strictly saprophytic throughout
its existence,

The extremely favorable conditions for plant growth at Buitenzorg made this
an unusually promising place for studying germination, and very soon after my
arrival there a quantity of plants of Ophioglossum moluccanum, or what was sup-
posed to be this species, was secured, and the spores were sown. Subsequent study
showed that at least three species grew together at Buitenzorg, so that it is not at
all certain that all of the germinating spores and the prothallia which were col-
lected later really belonged to O. moluccanum.

Since in all previous experiments with the Ophioglossacee germination had
been very slow, it was with much surprise that the first lot of spores that were sown,
when examined a week later, were found to be germinating very freely and had
evidently been growing for some days. New sowings were made, and in some cases
the first germination stages were evident within three days from the time the spores
were sown. Inasmuch as the spores contain no chlorophyll, this rapid germina-
tion is really remarkable. In the most favorable instances the greater part of the
spores germinated and many thousand germinating spores were studied.

The first sowings were made upon earth taken from where the plants were
growing; the earth was placed in small glass dishes and flooded with water; the
spores were then scattered over the surface of the water, some sinking, but the
greater part floating on the surface. In later experiments cavities were hollowed
out in the earth and these were filled with water, while the rest of the earth was
left wet, but not flooded. It was found that the spores germinated more promptly
in the water than on the wet earth, and this suggested that probably under natural
conditions germination occurs where the spores fall in slight depressions which are
filled with water for a time after heavy rains. The prothallia of Helminthostachys,
to judge from the locality where they were found in the Barrawa Forest, occurred
only where the forest was subject to inundation, and it may be that immersion in
water is necessary for the germination of Ophroglossum moluccanum, or at any rate
facilitates germination. ‘The older prothallia of this species which were found in
Buitenzorg were growing in low ground between the projecting roots of trees, where
water might very well stand for some days in wet weather.

The first sign of germination consists in the enlargement of the spore contents,
which soon burst the rigid outer membrane along the three lines upon its ventral
face, and through the cleft thus formed the spore contents, surrounded by the col-
orless inner membrane (“endospore” or “intine’’) protrude as a blunt papilla
(plate 1, fig. 2). The first division wall is transverse and is soon followed by a
second wall in the upper cell (i. e., the one turned away from the opening). The
second wall is at right angles to the first, and the young prothallium now consists of
three cells, the basal one, which is partly exposed through the cleft at the upper side
of the spore, and the two upper cells, which have more dense contents than the
basal one. The basal cell in position corresponds to the first rhizoid in the germi-
nating spore of the typical ferns, but it was never found to become extended into a
true rhizoid, and no rhizoids were seen in any of the very young prothallia.

While Ophroglossum moluccanum and O. pendulum agree very closely in the
early stages of germination, in the latter species no trace of chlorophyll can be
detected at any time, but in O. moluccanum it is not uncommon to find from one to
three chloroplasts present. These chloroplasts are very pale in color, but it is
certain that a small amount of chlorophyll is present in some cases.

While most of the young prothallia of Ophioglossum moluccanum do not advance
beyond a three-celled stage, a few were found in which there were four cells, but all

THE GAMETOPHYTE 9

attempts to carry them beyond this stage failed and after exhausting the spore con-
tents they soon died. The small amount of chlorophyll occasionally found in these
young prothallia is evidently insufficient for their independent growth, and after a
few weeks the granular contents all disappear and the cells soon collapse, showing
that the young gametophyte has died from starvation.

A number of specimens of the rare Ophioglossum intermedium were collected
near Buitenzorg and a few ripe spores were also secured. These spores contain
somewhat less dense contents than those of the other species described and have a
more delicate epispore. Spores were sown on March 30 in Buitenzorg, and when
examined about two weeks later no germinations were found, nor did a second
examination about the end of April show any further results. On May 21, however,
two three-celled prothallia were found, and subsequently a small number of others,
but no later stages were discovered. The young prothallia appeared in every
respect like the similar stages in the other species (plate 1, fig. 6).

In Ophioglossum pendulum a number of young prothallia were found which
had increased very much in size and undergone further division. The first of
these were observed on April 3, and had oe from spores sown in Peradeniya
on February 9. These young prothallia (fig. 1, c) had from four to six cells. It
was found that in each case the mycorrhiza had connected itself with the young
prothallium, and evidently had caused a stimulus in its growth. In every case
where the young prothallium had more than three cells there was found associated
with it the mycorrhiza, which could be easily seen to penetrate into the basal cell.
The infection was in all cases due to fragments of mycelium, and in no case to any-
thing which could be interpreted as spores. The fungus was apparently growing
free in the humus where the spores were sown. ‘This soil, as we shall see, was taken
from about the roots of the sporophytes which furnished the spores.

The free surface of the basal cell has its wall decidedly thickened, and it was
here that the infection took place in all the specimens seen. The branching mycelium
of the mycorrhiza was closely applied to the surface of the cell and a haustortum was
sent down through the cell wall into the basal cell (fig. 1, m). This haustorium is
pointed at first, but after it penetrates into the cell it enlarges and assumes the form
of a somewhat thickened worm-shaped body, much thicker than the free mycelium
outside. In the cell infected with the fungus, the contents show the peculiar aggre-
gated appearance characteristic of the infected cells of the older prothallia. On
the 6th of April a specimen with seven cells was found. About a month later, a
number of other specimens were observed also, some of these having as many as
thirteen cells (plate 1, fg. 9). This was the largest number found in any of the
young prothallia.

The divisions of these young prothallia are mainly in the lower cells, so that
the apex, as in the prothallium of the true ferns, develops mainly from the lower of
the two original prothallial cells. The basal cell, however, also undergoes divisions,
and there is no very marked difference between the lower and upper ends of the
prothalltum. At this stage there is a marked resemblance, except for the absence
of chlorophyll, to the early germination stages of Lycopodium cernuum (Treub 1).
The mycorrhiza penetrates ne cells adjacent to the one first infected, but leaves the
apical region free, and this region probably remains permanently free from the
endophyte, as it does in the adult prothallium.

The number of young prothallia found was too small to make it possible to
determine exactly w hat may be considered to be the normal succession of cell divi-

sion, and whether at this early stage there is a definite apical cell could not be decided.
As will be seen from the figures, there is evidently a good deal of variation in the

10 THE OPHIOGLOSSALES

early divisions. In these larger prothallia there is already the beginning of an axial
tissue. Whether the cell x (plate 1, fig g) is to be regarded as an apical cell, it would
be hard to say.

Owing to my departure from Java about three months after the first observa-
tions were made, it was impossible to trace the development of the prothallia further,
but this much is certain—without the infection of the fungus, growth will not pro-
ceed beyond the three-celled stage, and apparently in O. pendulum no chlorophyll
will develop under any conditions, and the prothallium from its earliest stages must
be considered saprophytic i in its nutrition. Whether the oval body described as the
product of germination is to be considered as a sort of tubercle, such as is found in
Lycopodium cernuum, must be decided by further investigations. Lang’s descrip-
tions and figures of the smallest specimens which he discovered would indicate
that this is not the case in O. pendulum; but the tuberous body usually found at the
base of the older prothallia in O. moluccanum (and this is true also in O. vulgatum)
would indicate that in these species it is not impossible that a primary tubercle
is first formed and subsequently the fertile branch.

THE ADULT GAMETOPHYTE OF OPHIOGLOSSUM.
In 1856 Mettenius (Mettenius 1) found the gametophyte of O. pedunculosum

Desv., a tropical species, growing spontaneously in the pots where the plants had
been cultivated in the botanical garden at Leipzig. He did not succeed, however,
in making the spores germinate. ‘These prothallia were slender, subterranean
bodies, sometimes branched, sometimes without branches. They ranged in length
from 1.5 lines to 2 inches (fig. 3, 4, B). There was usually present a basal enlarge-
ment or tuber, from which the fertile part of the prothallium extended. The older
portions were brownish in color, the growing tips of the branch white. From the
surface there grew numerous short brown rhizoids. Archegonia and antheridia
grew more or less intermingled and were formed in large numbers. Except for the
greater size, these prothallia closely resemble those of O. moluccanum collected by
me in Buitenzorg; and as O. pedunculosum Desv. has been held to be a synonym
of O. moluccanum Schlecht, it is possible that Mettenius’s plants were the same as
those found by me growing in Buitenzorg in Java.*

The next account of the prothallium of Ophioglossum is that of Lang (Lang 1).
He collected in Ceylon specimens of the prothallia of Ophioglossum pendulum.
‘These were found in the Barrawa Reserve Forest, not far from Colombo, and were
buried in the humus accumulated between the leaf bases of Polypodium quercifolium,
an epiphytic fern to which O. pendulum is often attached. I visited this same locality
in February, 1906, but was unsuccessful in collecting the prothallia, although I
obtained numbers of the sporophytes. Some time after, however, when in Java, I
found a very large number of prothallia which were growing in much the same way
as those collected by Lang, except that in this case the fern to which the Ophio-
glossum was attached was the widespread bird’s-nest fern, Asplentum nidus.

Bruchmann has given a detailed account of the prothallium of the widespread
O. vulgatum, which agrees closely in its essential details with O. pedunculosum and
O. moluccanum. Bruchmann’s specimens were collected in the Thuringian Forest,
in a depression that was subjected at times to overflow, a condition paralleled by the
locations where the prothallia of Helminthostachys were collected by Lang and

* Cristensen in his recent Index Filicum (1906) regards O. moluccanum as a synonym of O. jelous Through the kind-
ness of Professor K. Goebel, I recently had an opportunity of examining some specimens of O. pedunculosum growing in the
botanical garden in Munich. These plants were the descendants of the specimens in Leipzig described by Mettenius and certainly
very closely resembled the typical O. moluccanum from Buitenzorg.

THE GAMETOPHYTE 11

myself, and also like the locality where most of my specimens of O. moluccanum
were found in. Java. This, in connection with my experiments in germinating the
spores of O. moluccanum, makes it not unlikely that actual submersion is a necessary
condition for the germination in the terrestrial species of Ophioglossum.

In April 1906, about fifty prothallia of O. moluccanum were collected by me
at Buitenzorg, where, as we have seen, this species is extremely abundant. Only a
small number of these were young enough to show the young reproductive organs,
and most of them had already developed the young sporophyte. The greater part
of these prothallia were found growing together in a slight depression between the
projecting roots of a tree.

These prothallia were slender bodies, from 5 to 10 millimeters in length, and none
of them branched. ‘They showed a more or less conspicuous basal tuber, like that
described by Mettenius for O. pedunculosum, and indeed they very closely resembled
his figures of the simpler forms of that species, but are very much smaller. The
youngest specimen found (plate 1, fig. 10) consisted of a small, irregular tuberous
body of a brownish color, from which grew a short appendage or branch, the tip of
which was white. The older ones also showed this basal tuber, but the cylindrical
branch was much longer. Owing to their slender form, the - prothallia are not always
easily distinguishable from roots, and in some cases a microscopic examination is
necessary before one can be sure of their real nature. Growing from the surface are
scattered short brown hairs like those described by Mettenius for O. pedunculosum.
Archegonia and antheridia are formed at an early period, and can be traced to the
base of the fertile branch, or in some cases may be found even upon the tuber. In
these specimens the reproductive organs seemed to be formed in rather smaller
numbers than is the case either in O. pedunculosum or O. vulgatum. Among the
prothallia was one very much larger than the others which had very large numbers
of old archegonia. It is highly probable that this represents a second species, but
unfortunately there was no means of determining to which of the two or three
forms associated under the name O. moluccanum it belonged.

The cells of the tuber and the lower part of the branch contain the character-
istic endophytic fungus, but the greater part of the fertile branch is quite free from
this, and the cells appear almost transparent, but they contain numerous small starch
granules. ‘The endophyte is much more abundant in the cells of the tuber. The
hyphe, which stain readily with gentian violet, are irregular in outline and branch
freely. Very often branches can be seen piercing the walls of adjacent cells.

In the living condition the pointed apex of the prothallium is pure white, and
even with a hand lens the projection of the antheridia is clearly evident. Mettenius
noticed this “varicose” appearance of the smaller prothallia in O. pedunculosum.
A median section of the branch shows that the end is decidedly pointed and has a
clearly defined apical cell. Owing to the very small amount of material available,
no satisfactory transverse section of the apex could be made, and it can not be told
whether the apical cell in transverse section is three-sided, as described by Bruch-
mann for O. vulgatum, or is four-sided, as it is in O. pendulum. In the smaller speci-
mens antheridia were more numerous than archegonia, although several of the latter
were present. The antheridia arise, in general, in acropetal succession, but it is
not unlikely that secondary ones may be formed also. ‘The archegonia are scattered
among the antheridia apparently without any definite order. In some specimens,
especially in the larger ones, the old archegonia were found in great numbers, many
more than the antheridia. In other specimens a considerable part of the pr othallium
was quite destitute of either archegonia or antheridia, and in this respect the pro-
thallium of O. moluccanum differs: from that of O. pedunculosum or O. vulgatum.

12 THE OPHIOGLOSSALES

The gametophyte of O. moluccanum shows a greatet or less number of rhizoids
both at the base and along the fertile branch (plate 1, fig. 10). In the more slender
forms, however, these rhizoids are few. ‘They are in some cases two-celled, but more
commonly consist of a single elongated cell. It is not unusual to find within this the
penetrating filament of the mycorrhiza, as has been described for other species
of Ophioglossum. ‘The rhizoids are much longer relatively than in O. pendulum.
According to Bruchmann, the rhizoids are quite absent from the prothallia of O.
vulgatum.

Mettenius states that in O. pedunculosum the prothallia often appear above the
surface of the earth, and they then become somewhat flattened and sometimes
divided into several small lobes, and in such cases chlorophyll is developed. Met-
tenius, however, does not note any further development of these green lobes.
Bruchmann found that chlorophyll might also develop in O. vulgatum, when the
prothallia were exposed to the light, but he did not find any flattening of the apex.
Owing to the very small number of growing prothallia found by me, I could not
test the power of developing chlorophyll in O. moluccanum, but the occurrence of
chromatophores in the germinating spores makes it highly probable that chlorophyll
may be developed in the older prothallia under the stimulus of light.

pr) | \
tY/ \
1g lt)
ye jh
« (f.
eet
oe ¢

\
pre}

Fic. 2.

a

Gametophytes, pr, and young sporophytes of Ophioglossum moluccanum and allied species, slightly enlarged. C and F from
Hakgala, Ceylon; the others from Buitenzorg, Java; &, bud on primary root;/, primary leaf; 1*, secondary leaf; ¢, tuberous
enlargement at base of gametophyte.

The small size of the prothallium in O. moluccanum and the cessation of growth
after the sporophyte is formed indicate that the gametophyte lives only for one
season, and this is probably the case also in Helminthostachys. In this respect
O. moluccanum and its allies differ markedly from O. pendulum and O. vulgatum,
where the gametophyte lives for many years.

At Hakgala, in Ceylon, an undetermined species of Ophioglossum of the type
of O. reticulatum is common. After careful search, a few prothallia which closely
resembled those of O. moluccanum were collected (fig. 2, C, F). The material was
too scanty to make a detailed study possible, but from the external appearance it is
likely that the structural details would closely resemble those of O. moluccanum.

The prothallium of Ophioglossum vulgatum, according to Bruchmann (Bruch-
mann 1), closely resembles that of O. moluccanum, but is very much larger, some-
times reaching a length of 6 centimeters, and it is not infrequently branched

THE GAMETOPHYTE 13

(fig 3, C). There is a more or less conspicuous basal tuber, like that found in
O. moluccanum, and from this extends a branch bearing the reproductive organs,
but, unlike the prothal-
tlum of O. moluccanum,
there seems to be a
complete absence of
ithizoids. In general,
the form is more irreg-
ular than that of O.
moluccanum and more-
over it is very long-
lived. The branches
may become detached
and thus form new in-
dividuals. From the
rate of growth in speci-
mens kept under ob-
servation for several A, B. Gametophytes of Ophioglossum pedunculosum (after Mettenius).

mont h So Bruchmann C, D. Gametophytes of O. vulgatum (after Bruchmann).

concluded that the y E-G. Gametophytes of O. pendulum. sp, young sporophyte; r, secondary root.
might live for twenty years or more. Where the apical growth of a branch is
interfered with, there may be a formation of adventitious buds, a phenomenon
which is also common in O. pendulum.

Ophioglossum (Ophtoderma) pendulum, a remarkable epiphytic species wide-
spread through the tropics of the Old World and reaching to Hawau, is the giant
of the order, the pendent ribbon-shaped leaves sometimes attaining a length of
1.5 meters. The sporophyte grows rooted in masses of humus, either upon the
rough trunk of a tree fern or palm, or hanging from the mass of humus accumu-
lated about the base of certain epiphytic ferns. The bird’s-nest fern, Asplenrum
nidus, furnishes the favorite substratum for this species in the forest of Tjibodas in
Java, where my material was collected.

The young prothallium in O. pendulum is an ovoid body, the somewhat smaller
forward portion corresponding to the fertile branch in O. moluccanum (see Lang 1,
page 25). The older ones become very much larger than in any other species that
has been described, and they branch freely in all directions, except as their growth
is controlled by their position. They are always found buried in a mass of humus
between the imbricated leaf bases of the fern, and are often much flattened by the
pressure of the leaves between which they are confined. Branches extend in all
directions, but their growth is to some extent controlled by the inclosing leaf bases
and also by the tangled mass of roots of the fern, which growin all directions through
the mass of humus and among which the branches of the prothallium of the Op/ro-
glossum extend. In one instance several hundred were collected from one large
plant of Asplenium nidus. The prothallia closely resemble Lang’s figures and
descriptions, but in many cases are very much larger and more extensively branched
than any of the specimens collected by him in Ceylon (plate 1, figs. 11-14). ‘The
larger prothallia may be stellate in form, but they are usually very irregular. The
branches penetrate in all directions between the dense tangle of roots which the
Asplenium sends into the humus between its persistent leaf bases, and on pulling
these back a mass of fine humus is found, held together by the mat of roots so that
it can be removed intact. The prothallia are excessively brittle, and it is practically
impossible to remove the larger ones without a loss of some of the numerous branches.

Fic. 3.

14 THE OPHIOGLOSSALES

These break off at the least touch, and no doubt serve to propagate the gametophyte,
which is apparently capable of unlimited growth in this way. It is often impossible
to say whether the smaller gametophytes that are found loose in the humus are
anything more than branches which have become spontaneously separated from
the larger prothallia.

The older parts of the gametophyte are dark brown in color, but the tips of the
branches are white, as.in the other species. ‘The branching, as we have seen, may
be very irregular, and old fragments kept moist often send out great numbers of
adventitious buds (plate 1, fig. 11) which apparently in time develop into normal
prothallia. A number of the commoner forms are shown in the figures. Plate 1,
fig. 14, represents the jargest-one met with. This is by no means complete, as a

Fic. 4.

A. Longitudinal section of apex of gametophyte of Ophioglossum moluccanum. 6 antheridia; archegonia;
em, two-celled embryo.

B. Apex more highly magnified, showing apical cell, x.

C. Transverse section of a branch of the gametophyte of Ophtoglossum pendulum.

D. Apical cell of same.

E, F. Short hairs from gametophyte of O. pendulum; in E may be scen the endophytic fungus filaments.

number of branches were unavoidably broken off in removing it from among the
tangle of roots in which it was embedded. ‘This specimen measured about 15
millimeters in diameter—more than twice the size of the largest specimen secured by
Lang. The surface of the older parts of the prothallium shows a slightly roughened
appearance due to the numerous very short papillate hairs which occur upon
it. These are never of the slender form found in O. moluccanum and perhaps
are not properly to be considered as rhizoids. Dotted over the surface are pale
brown spots, easily seen with the naked eye, and these on examination are found to
be the large, empty antheridia. The branching is sometimes dichotomous, but
lateral branches may arise at almost any point, and old fragments of the prothallia,
as already indicated, often develop many adventitious buds, a condition of things
which apparently obtains also in the long-lived prothallia of O. vulgatum. The
rate of growth of prothallia kept by the writer for more than a year, as well as their

THE GAMETOPHYTE 15

position in the humus about the plant, where they are found in the older parts
between leaves which must have been dead for many years, indicate that they are
very long-lived and, as we have seen, by the ready separation of the branches they
are easily propagated.

THE HISTOLOGY OF THE GAMETOPHYTE.

The younger portions of the growing branches are composed of thin-walled,
colorless parenchyma, whose cells have a conspicuous nucleus, and usually numerous
small starch granules. In the older portions of the gametophyte the tissue becomes
infected with the often-described endophytic fungus. Practically all of the cells of
the basal tuber are thus infested, but in the fertile branches the central tissue is
usually free from the fungus, and this medulla-like central tissue is surrounded by a
more or less definite mantle of cells, in which the endophyte is especially luxuri-
ant. The outermost cells are practically free from fungus, although new infections
probably may take place there through these outer cells. In O. moluccanum the
endophyte is much less developed than in O. pendulum, this no doubt being corre-
lated with the much briefer duration of the gametophyte in the former species.
According to Bruchmann, the endophyte is strongly developed also in O. vulgatum.
The endophyte, as in the other forms that have been studied, is quite absent from the
apical region of the branches. The limits of the infested zone are not very clearly
marked and any cell of the older tissue of the gametophyte may harbor the fungus.

Fic. 5.

A. Longitudinal section of gametophyte apex of O phtoglossum vulgatum. X150.
B. Transverse section of gametophyte apex. a, the apical cell.

C. Archegonium. X225.

D. Two free spermatozoids. 550. (All figures after Bruchmann.)

The apical cell in O. pendulum is usually a four-sided pyramid, and not tetra-
hedral, as it is in O. vulgatum. In longitudinal section (fig. 4, D), the apical cell
appears triangular with a fairly regular segmentation, but there is also active division
in the adjacent tissue and apparently the segmentation of the apical cell is not very
rapid. Cross-sections show the apical cell to be approximately four-sided (fig. 16, 4),
but the sides are not always of equal length and sometimes it is almost triangular in
outline; possibly it may be that in some cases, as in O. vulgatum, it 1s tetrahedral.
There seems to be no absolute rule, however, as to the succession of divisions in the
young segments. A more or less definite superficial layer arises from the first
periclinal divisions, but anticlinals follow rapidly.

16 THE OPHIOGLOSSALES
THE GAMETOPHYTE OF BOTRYCHIUM.

Hofmeister (Hofmeister 1), in his studies of the Archegoniates, has included
Botrychium lunarta, whose prothallium he discovered in 1854. No further contri-
butions to our knowledge of the subject are recorded until 1893, when the writer dis-
covered at Grosse Ile, Michigan, a number of old prothallia of B. virginianum, with
the young sporophytes attached. The earliest germination stages of this species
were also secured. In 1895, Prof. E. C. Jeffrey collected at several points in Canada
a large number of prothallia of this species, and his account ( Jeffrey 1) is much the
most satisfactory one which had appeared up to that time. In the spring of 1903
Lyon (Lyon 1) discovered prothallia of B. obliquum in Minnesota, and the following
year secured a few specimens of B. simplex and B. matricartefolium, but he has only
published a brief note in regard to these species. He states that the reproductive
organs in B. obliquum “ differ essentially from those of B. virginianum,” but he does
not explain in what these differences consist. Bruchmann, who has added so much
to our knowledge of the gametophyte of the European Lycopodiacea and Ophio-
glossacew, has recently given. a very satisfactory account of the prothallium and
embryo of B. /unarta, which he found in various parts of Germany and Switzerland.
He corrected certain errors made by Hofmeister in his account of the same species.
(Bruchmann 2.)

oe D

Fic. 6.—Botrychium virginianum.

A, B. Germinating spore (B, optical section).
C. Three gametophytes, X3; ¢m, embryo.
D. Section of gametophyte, X12; the shaded region is that occupied by the endophyte. 6 antheridia.
E. Apical region of gametophyte, 150.
F. Short multicellular hair or paraphysis.

Owing to the kindness of Professor Jeffrey, a large number of prothallia and
young sporophytes of B. virginianum, together with several slides showing the sexual
organs and embryos, were put at my disposal. This has made it possible for me to
make a very satisfactory study of the reproductive organs and embryo in this species.

The spores of Botrychium, like those of Ophioglossum, are of the tetrahedral
type and are quite colorless, their contents showing the usual granular appearance,
but without any trace of chlorophyll. The early stages of germination are exactly
like those of Ophioglossum, the first division wall being transverse, this being then
followed by a second wall in the inner cell at right angles to the primary wall (hg. 6,
A,B). A few chloroplasts were seen in some of the cells, but this does not seem to
be a constant character and perhaps was an abnormality due to the spores having

THE GAMETOPHYTE GZ

germinated in the light. Bruchmann (Bruchmann 2, page 207) also found the
earliest stages in B. /unaria, and these corresponded exactly to those in B. wir-
gintanum.

The gametophyte of B. virgintanum is a large, tuber-like body, which grows
at a depth of about 10 centimeters below the surface of the earth. The smallest
of the specimens found by Jeffrey were 2 millimeters in length by 1.5 millimeters
in breadth, exceeding in size the fully developed prothallia of B. lunarta. The
older ones may reach a length of 20 millimeters. The young prothallia are
quite smoothly oval in outline (fg. 6, C), while the older ones are more or less

Fic. 8.—Botrychium lunaria (after Bruchmann).

A. Two young gametophytes.
B. An older one, with sporophyte, sp, attached.

Fic. 7.

x16.
A. Young sporophyte of Botrychium virgint- C. Surface view of two antheridia, showing opercu-
anum attached to gametophyte, pr. <2. lar cells (shaded). 100.
B. A gametophyte with small sporophyte, sp. X4. D. A spermatozoid. X 500.

irregular, and occasionally the anterior end is divided into two equal lobes,
probably as a result of dichotomy. As in Ophroglossum, the older parts of the
gametophyte are brownish in color, while the young apex appears white. In their
earlier stages they are covered with numerous rhizoids, which disappear more or
less completely as the prothallium becomes older. The forward end 1s slightly
pointed and there is a definite growing point. The antheridia make their appear-
ance first, and together with the archegonia are formed only upon the upper surface
of the dorsiventral thallus, which is noticeably different in form from the cylindrical

radially constructed prothallium of Ophioglossum.
:

18 THE OPHIOGLOSSALES

The antheridia form a more or less evident row, even in the very young
prothallium, and later this median row of antheridia ts raised upon an elevated
ridge, upon whose sides the archegonia later make their appearance (fig. 6, D).

The gametophyte of B. lunarta closely resembles the early stages of B. virgin-
‘anum. It is very much smaller and rarely exceeds a length of 2 millimeters, and,
like the young stages in B. virginianum, it is covered with many long rhizoids
(fig.8, 4, B.) The smaller prothallia are globular or oval in shape, the larger ones
somewhat heart-shaped. Hofmeister states that the antheridia occur upon the upper
surface and the archegonia below; but Bruchmann found that both archegonia and
antheridia were confined to the upper surface, as in B. virgintanum. As in the
latter, also, the dorsal ridge is present, bearing the antheridia upon its crest and the
archegonia upon its flanks.

The large prothallia of B. urgintanum live for many years, and Jeffrey even
found a plant bearing spores, which was still connected with a prothallium. It is
probable that the very much smaller prothallia of B. /unarta have a shorter duration,
but in this species also the prothallium persists for some time after the young
sporophyte is established.

THE HISTOLOGY OF THE GAMETOPHYTE OF BOTRYCHIUM.

In B. virginianum the forward part of the prothallium is made up of colorless

tissue, which extends for some distance beyond the youngest antheridia. The apical

meristem in this species (fig. 6, £) lies on the upper side of the prothallium; in a
vertical longitudinal section it shows a group of columnar cells, one of which is

Fic. 9.

A. Transverse section of a gametophyte of Ophioglossum pendulum, showing position of
endophytic fungus. X20. The shaded region is occupied by the endophyte.

B. Endophyte from prothallium of Botrychium virginianum.

C. Sporangium-like enlargements of endophyte.

probably the apical cell; but this is not absolutely certain. In B. lunaria (see
Bruchmann 2, page 209) the apical meristem occupies the middle region of the
anterior surface of the prothallium, and is of very limited extent. As in B. vir-
gintanum, its cells appear columnar in form, but neither in longitudinal section nor
in a surface view could a single initial cell be recognized.

The rhizoids in B. virginianum are from I to 4 millimeters in length and may
be multicellular, especially those which arise from the crest and flanks of the pro-
thallium, while those which originate from the base are unicellular and longer than
these multicellular ones. It is not unlikely that these multicellular structures are
rather of the nature of paraphyses than true rhizoids. In B. lunarta the rhizoids
seem to be, usually at least, unicellular. In both species the rhizoids soon turn
brown and their walls become strongly cutinized. Both Jeffrey and Bruchmann

THE GAMETOPHYTE 19

observed the penetration of fungus hyphz into the rhizoids, and they believe that
the fungus which occurs within the thallus is, mainly at least, due to this method of
infection. From a comparison with the early infection of the young prothallium
in Ophioglossum, it seems to me more probable that the young prothallium in
Botrychium also is infected at a very early period and that the endophyte, once
established within its tissues, grows with the development of the gametophyte, the
secondary infection through the rhizoids of the older gametophyte being of minor
importance.

In both species of Botrychium the infected region comprises the greater part
of the central tissue, leaving only a comparatively narrow peripheral region free
from the endophyte. This uninfected area is thicker upon the upper surface and
comprises the whole of the meristematic region, together with the developing sexual
organs. As in Ophioglossum, this uninfected tissue contains small starch granules
in considerable numbers, but not much else in the way of granular contents. The
invasion of the fungus results in the destruction of the starch and the accumulation
of large amounts of oil. This oil, according to Jeffrey, is not readily soluble in
alcohol, and the cells containing it, both in fresh and stained sections, appear dark-
colored.

THE GAMETOPHYTE OF HELMINTHOSTACHYS.

The monotypic Helminthostachys zeylanica is not uncommon throughout the
lowlands of the Indo-Malayan region and often occurs in large numbers. The only
account yet published of the gametophyte is that of Lang (Lang 1). The prothallia
which he describes were collected in part by himself in the Barrawa Reserve Forest
in Ceylon in March 1gor. Other material studied by Lang was collected at the same
place by Mr. Coomara Swamy. I made a visit to the same locality in February
1906, and also found a considerable number of prothallia, but all of these had been
fertilized and had attached to them the young sporophyte, so that no young repro-
ductive organs were found. The forest where they were collected is subject to
inundation from a river which runs through it, and it was in the parts that had been
overflowed that the young plants were discovered. This makes it not unlikely that,
as in the case of Ophioglossum moluccanum, germination 1s favored by having the
spores immersed in water, and this may be a necessary condition for the first stages
of germination.

A quantity of ripe spores were collected and various attempts were made to
germinate these, but without success, and, as none of the specimens obtained by
Lang were very young, the early history of the prothallium still remains to be
investigated.

As in the other Ophioglossacez, the prothallia are subterranean, occurring at a
depth of from 5 to 6 centimeters in the earth. In form (figs. 10, 11) they are some-
what intermediate between Botrychium and Ophioglossum, but are on the whole
more like the latter. They are somewhat irregular in outline, with a broad base,
recalling the basal tuber of O. moluccanum, but this tuber is relatively larger and
more lobed. From this basal tuberous portion a short upright branch extends,
much as in Ophioglossum moluccanum, but tt is relatively thicker and shorter. The
whole gametophyte is radial in structure, as in Ophioglossum, and thus differs
strikingly from the dorsiventral gametophyte of Botrychium. The basal enlarged
portion is brown in color and covered with rhizoids, which are mostly absent from
the upper, more slender part upon which the reproductive organs are borne.

Lang found that there is a tendency to dicecism in the prothallia, some pro-
ducing only antheridia (figure 11, A), while in others archegonia predominate,

90 THE OPHIOGLOSSALES

although in the latter a few antheridia are almost always developed before the arche-
gonia appear.

In the male prothallium the basal “vegetative” portion is relatively small
and often is irregularly lobed, these lobes
being not of the nature of true branches,
but merely the result of unequal growth.
The female gametophyte (fg. 10) has the
basal region relatively larger and is even
more irregular in form than the male,
while the fertile region is shorter and
wider. Some of the more elongated types
of the male gametophyte are quite similar
to the simple prothallium of Ophroglossum
moluccanum. As in the other genera, the
endophytic fungus is always present and
occupies much the same position as in
Botrychium.

Lang found that the growth is due
to the activity of a single apical cell having
the form of a four-sided pyramid, much
like that found in Ophioglossum pendulum.
The lateral segments divide by periclinal
walls, and from the superficial cells thus
formed originates the layer of tissue from
which the sexual organs arise. ‘The inner
cells contribute to the axial tissue of the
gametophyte. The antheridia in the male

_ plants are evenly distributed about the

\ Ganev (pr) of Helmitnnachys, solani th periphery, so that in cross-section they form

B. An older sporophyte, with fully-developed second leaf. a nearly uniform circle. The axial tissue,

cua eee Sree ot especially in the male prothallium, has the

} cells much elongated, and Lang thinks

they are useful in the conduction of plastic material from the basal region of the
prothallium to the growing point.

The outer part of the basal region consists of two or three layers of somewhat
flattened cells, which, like the corresponding tissue in Botryc chium, are free from the
endophyte. From some of these superficial cells there are developed unicellular,
elongated rhizoids, with markedly cutinized walls. This cutinization extends to
the outer walls of the superficial cells, while the inner walls of these cells, as well as
those of the inner tissue, show the cellulose reaction. The formation of the lobes
of the basal region are due, not to definite apical growth, but to irregular cell divi-
sions in the outer layers, which remain free from the fungus which occupies the
greater part of the central region of the lobes, as well as the axis of the main shoot
of the prothallium.

‘The central tissue is made up of about equal parts of infected and uninfected
cells. ‘The latter, as in the other cases investigated, contain starch granules which
are absent from the cells harboring the fungus. Fungus hyphz were seen in many
cases to penetrate the rhizoids, but it is highly probable that in Helminthostachys
also there is a primary infection at an early stage in the germination of the spores.

Lang notes that in the older male prothallia the fungus is dead and the further
growth of the prothallium is dependent upon the amount of reserve food (mainly

Fic. 10.

THE GAMETOPHYTE Dl

starch) which 1s left in the cells. It is not clear what role the endophyte plays in
the manufacture of the reserve food materials upon which the further growth of the
prothallium depends. It is highly probable, however, that some of the necessary
organic elements are derived from the destruction of the fungus tissues which serve
as food for the further development of the prothalltum. While no data are at hand
to prove this, the lack of permanent growing tissue in the prothallium and the com-
plete destruction of the fungus make it highly probable that the life of the gameto-
phyte in Helminthostachys is restricted to a single season, as it is in Ophioglossum
moluccanum. E

Fic, 11.
A. Male gametophyte of Helminthostachys. 8. C. Surface view of ripe antheridium, showing opercular cells.
B. Young antheridium. X225. D. An old archegonium. X about 200.

(Figs. A-C, after Lang.)

HE ENDOPHYTE.

The endophytic fungus which inhabits the gametophyte in all of the Ophio-
glossacee is very much alike in all of the species, differing only slightly in size in
different forms (fig. g). A special study was made of this endophyte in Ophio-
glossum pendulum, where it is especially well developed. As we have already seen,
the endophyte is absent from the younger parts of the prothallium, but in the older
parts it is exceedingly conspicuous. Sometimes fragments of a fungus are found
outside the prothallium, growing in the humus, and these are evidently the same
forms that infect the very young prothallium when it arises from the germinating
spores. These external hyphe in some cases have an occasional septum, and this
is also the case in those forms which infect the young prothallium. In all of the
hyphz seen within the prothallium, however, these septa seem quite absent. The
infection of the prothallium through the rhizoids has been noted in all the species,
but, as we have already stated, it is probable that the endophyte is derived mainly
from the first infection of the very young gametophyte. An examination of the young
cells before the entrance of the fungus shows a conspicuous nucleus and numerous
starch grains, which stain very strongly with gentian violet. The invading mycelium,
whether from the outside of the prothallium or from the adjacent cells, penetrates
the cell wall and ramifies within the cell, the growth being entirely intracellular.
The hyphz are noticeably thicker than those of the external mycorrhiza.

The endophyte is perfectly fixed with 1 per cent chromic acid and it stains
well with the double stain of gentian violet and safranine, the walls assuming a
violet color and the numerous nuclei staining deep red. In the younger hyphe,
which are of varying sizes, the protoplasm is densely granular, but in the older ones

22 THE OPHIOGLOSSALES

4

the granular appearance disappears to a considerable extent, though the nuclei
continue to stain strongly. The fungus is quite variable in form. Sometimes the
filaments are nearly straight, running from cell to cell and branching sparingly.
Sometimes a cell is completely filled with a dense tangle of hypha, while in other
cases there are sack-like vesicles of very irregular form. Not infrequently, quite
regular, nearly globular bodies are seen, recalling the odgonia of the Peronospore.
These at first contain comparatively few nuclei, scattered through the granular
cytoplasm, but in the older ones the nuclei are very numerous and decidedly larger.
It looks sometimes as if this were a preparation for the formation of spores, but no
certain evidence of the formation of such spores could be seen, although in several
instances there was an appearance which might point to this. Structures resembling
the “conidia,” described by Jeffrey for Botrychium (Jeffrey 1, page 12), were seen
and are probably the same thing.

As the fungus invades the young cells, irregular, strongly-staining clumps are
formed by the aggregation and breaking down of the starch grains. The nucleus
of the host cell appears to be but slightly affected by the growth of the fungus, and
can usually be found quite unchanged, even in those cells which are almost com-
pletely filled by the endophyte. Finally, the thin-walled vesicular growths of the
fungus are quite broken down and probably serve to nourish the cells of the gameto-
phyte, which is thus parasitic upon the cells of the fungus. ‘The systematic position
of the fungus is doubtful. The varicose, swollen hyph found at certain stages
closely resemble a parasitic fungus, Completoria complens, which is sometimes
extremely destructive to green fern prothallia. The odgonium-like organs, often
present, suggest Pythium, a parasitic fungus belonging to the Peronosporez.
Jeffrey (Jeffrey 1, page 13) thinks the endophyte may fairly be regarded as an
intermediate form between the two genera, Completoria and Pythium, and says that
in this case Completoria should be placed in the Peronosporex instead of in the
E-ntomophthoree, where it has been placed by some students of the Fungi.

THE SEXUAL ORGANS.
THE ANTHERIDIUM

The antheridium in all of the Ophioglossacez is of much the same type and
closely resembles that of the Marattiacee and also Equisetum and Lycopodium.
The mother cell does not project at all above the level of the adjacent tissue, and in
all cases the first division separates a superficial or cover cell from an inner one, the
latter by further divisions giving rise to a mass of sperm cells which may be very
numerous. The cover cell also divides, sometimes only in one plan, sometimes
(e. g., in Botrychium) having also periclinal divisions. At maturity the antheridium
may project more or less strongly, but this is not always the case.

THE ANTHERIDIUM OF OPHIOGLOSSUM

The antheridium was first described by Mettenius in Ophioglossum pedunculo-
sum, and later Lang described it for O. pendulum and Bruchmann for O. vulgatum.
The present account is based mainly upon my own studies of O. moluccanum and
O. pendulum.

The mother cell of the antheridium, which may arise very close to the growing
point of the prothallium, lies flush with the neighboring cells, but later it may
become more or less elevated above the surface, forming a prominence which, in
slender prothallia, like those of Ophioglossum moluccanum, may give an irregular
undulate outline to the branch which bears them (fig. 4, 4). In O. pendulum

oO

THE GAMETOPHYTE p

this projection is less marked, although this may be somewhat decided in the
ripe antheridium. The first division in the inner cell is usually vertical, but may be
transverse, at least in O. pendulum (fig. 13, 4). The second walls intersect the
first at right angles, and there are always four nearly equal inner cells resulting
(fig. 13, D). The third set of walls is vertical, and the next, in some cases at least,
is in the same direction. This is not true, however, of the deeper and narrower type
of antheridium. Further divisions occur until the number of spermatocytes is very
large. The fully developed mass of spermatocytes is plainly visible to the naked
eye, and in O. pendulum may reach a diameter of more than 325 #. 250 cells and
upward may be counted in a single section of a large antheridium, and this would
mean that there are several thousand in the whole antheridium—perhaps more than
in any other Pteridophyte. In O. moluccanum (fig. 12), the number of spermatocytes
is much smaller, while in this regard the antheridium of O. vulgatum appears to be
intermediate between that of O. moluccanum and O. pendulum.

BiG. 12.—O phioglossum moluccanum.

A. Ripe antheridium. 180.
B, C. Young antheridia. 320.
D. Surface view of antheridium, showing opercular cell.

The nuclei of the young cells show a conspicuous nucleolus, which becomes less
marked in the later stages of the antheridium. According to Mettenius, the outer
wall of the antheridium in O. pedunculosum is composed of two layers of cells; but

both Lang and Bruchmann found that the central part of this outer wall of the

Fic. 13.—Development of the antheridium in Ophioglossum pendulum.

A. Median section of gametophyte, apex, showing apical cell, x, and two young antheridia, 6. 175.
B. Transverse section of apex; x, apical cell.

C, D. Median sections of young antheridia.

E. Median section of a nearly ripe antheridium.

F. Surface view of ripe antheridium; 9, opercular cell.

24 THE OPHIOGLOSSALES

antheridium is but one cell in thickness, and I have verified this for both of the
species under consideration.

The first wall to be formed in the cover cell is a nearly median one and vertical
(fig. 12, B), and this is followed by a second wall which intersects it, as well as one
of the lateral walls of the primary cover cell, so as to include a nearly triangular cell.
In this triangular cell there are later formed, as both Bruchmann and Lang showed,
a varying number of segments arranged spirally in the fashion of the segments of a
three-sided apical cell (hg. 13, F). The same thing occurs in Lycopodium (Treub 1).
I have also found a similar condition in the antheridium both of the Marattiacez
and of Equisetum. The last-formed triangular cell is the opercular cell (fig. 13, F, 0).
From the prothallial tissue which adjoins the sperm cells are cut off flattened cells
which surround the sperm cells with a more or less definite layer of “ mantle” cells.
The limits of the original cover cell are usually plainly visible in both longitudinal
and surface sections.

THE ANTHERIDIUM OF BOTRYCHIUM.

The antheridia in Botrychium occur only upon the dorsal surface of the gam-
etophyte, which is always moneecious. The first antheridia in B. wirginianum (see
Jeffrey 1, page 8), form a small cluster which is not noticeably raised above the
general level of the prothallium, and from this primary cluster extends a single
median line of antheridia toward the apex of the gametophyte. Later this median
region becomes raised and forms a conspicuous ridge along whose crest the anthe-
idia are borne. In B. lunaria, according to Bruchmann, the arrangement is
much the same.

Fic. 14.—Development of the antheridium in Botrychium virginianum.

A-D. Longitudinal sections of young antheridia. 320.
E-H. Transverse sections. F,G show only the young spermatocytes. H, surface view showing opercular
cell, o. I, section of two ripe antheridia. 80.

The development of the antheridium is very much like that of Ophroglossum.
The first division, as in the latter, is a periclinal one, separating the primary cover
cell from the mother cell of the spermatocytes. The divisions in the cover cell,
however, differ somewhat from those in Ophioglossum, in that periclinal walls

THE GAMETOPHYTE 95

are formed in some of these, so that the cover becomes to some extent double.
Jeffrey states that the cover is two layers throughout, but Bruchmann found that
some of the cells—two and sometimes three—remain undivided and that one of
these undivided cells functions as the opercular cell. I have examined this point
carefully in Botrychium virginianum and find that there is an opercular cell in this
species also. The division walls in the primary cover cell usually intersect at right
angles, so that the opercular cell is four-sided, instead of triangular, as in Ophio-
glossum (fig. 14, 1); but exceptionally it may have the triangular form. In the
dehiscence of the antheridium only a single opercular cell is destroyed, not two
superimposed cells, as Jeffrey supposed to be the case.

The divisions in the central cell are very much the same as in Ophioglossum.
Whether the first division is regularly transverse or vertical could not be determined,
as no examples of the first division were found. ‘The earliest stages seen after the
first separation of the cover cell had four inner cells arranged quadrant-wise, but
it was not clear which was the primary wall. The quadrant division is, usually at
least, followed by an octant division, and these early divisions may sometimes be
recognized for a long while, as there is not much displacement of the cells due to the
subsequent divisions. In the later stages the primary divisions can no longer be
made out clearly. The number of sperm cells finally formed may be very large—
more than a thousand in the largest antheridia--thus nearly or quite equaling the
number found in Ophioglossum pendulum, although the sperm cells are very much
less in size than in the latter and the antheridium correspondingly smaller. Some-
times the antheridium is divided into irregular chambers, apparently due to the
persistence of some of the early division walls (fg. 15, B).

Fic. 15.—Botrychium virginianum.

A. Longitudinal section of a nearly ripe, but rather small, antheridium. about 200.

B. Section of a ripe antheridium which has discharged the spermatozoids; some cell-walls have remained,
forming irregular chambers, and retaining some of the spermatozoids.

C. A surface view of a ripe antheridium, showing square opercular cell.

The antheridium of B. /unaria, according to Bruchmann, is smaller than that
of B. virginianum, but the size of the spermatocytes and spermatozoids seems to be

about the same (fig. 8, D).
THE ANTHERIDIUM OF HELMINTHOSTACHYS.

The antheridium of Helminthostachys has been studied by Lang, and it 1s
evident from his account that it resembles that of Botrychium much more than it
does that of Ophioglossum. As in the former, the primary cover cell undergoes
periclinal divisions as well as anticlinal ones, but there are from two to four cells
which do not divide by periclinal walls, and one of these cells becomes the opercular
cell (fg. 11, C). These four undivided cells stain more strongly than the other cells
of the cover, but only one of them is broken down at the time of dehiscence. ‘hese

26 THE OPHIOGLOSSALES

cells, as in the case of Botrychium lunarta, are nearly square in outline, most of the
walls in the cover cells being at right angles to each other, as in Botrychium.

The divisions in the central cell are very similar to those in Ophioglossum and
Botrychium, and the original quadrant divisions are perceptible for some time.
The number of spermatocytes, as in Ophioglossum and Botrychium, may be very large.
The spermatozoids were not seen by Lang, but from a comparison of the nuclei of
the spermatocytes they are apparently of about the same size as those of Botrychium.

SPERMATOGENESIS.

Ophioglossum i is especially suited to a study of spermatogenesis, owing to the
very large size of the spermatozoids. Those of O. pendulum are probably the
largest known among the Pteridophytes. In material fixed with 1 per cent chromic
acid, or weak Flemming’s solution, and stained with gentian violet and aniline
safranine, the coloring is beautifully clear and the blepharoplast stains with extra-
ordinary sharpness. The spermatozoids of O. pendulum are larger than those of
O. moluccanum or O. vulgatum, but the development | is very much the same.

If the sperm cells are examined previous to the final division to form the
spermatocytes (plate 1, fig. 16), the nucleus will be seen to have a small but distinct
nucleolus and a dense reticulum. ‘The whole nucleus stains strongly with safranine.
The cytoplasm is fairly dense, with granules of various kinds in it. In material
fixed with Flemming’ s solution there are often small black specks, probably fatty
bodies, which sometimes interfere somewhat with the study of the cytoplasm. In
well-stained sections the blepharoplasts may be seen as two small, rounded bodies
of a violet color (plate 1, fig. 16, 5/) lying near the nucleus. Several cases of the final
nuclear divisions were met with, but all of these were in material fixed with chromic
acid, and the blepharoplasts were not very well differentiated (plate 2, fig. 22). The
nuclear spindle 1 is very distinct, and the very numerous chromosomes are so crowded
that it was quite impossible to determine their number exactly, but it is very large.
In the young spermatocytes (plate 2, fig. 26) the nucleus shows a more or less con-
spicuous reticulum, but the nucleolus has disappeared, as it usually does at this
stage in all the forms that have been studied. The further development of the
spermatozoid corresponds very closely with that of Equisetum (see Campbell 4 and
Belajeff 1, 2). One of the blepharoplasts i in the primary spermatocyte goes with
each daughter cell (the definitive spermatocyte) and can be seen as a distinct rounded
body lying near the nucleus (plate 2, fig. 24). In some cases what appeared to be
the blepharoplast was lying in a depression at the periphery of the nucleus, and
looked very much like a nucleolus,

Before the nucleus undergoes any marked change, the blepharoplast begins

to elongate (plate 2, figs. 26, 27) and assumes the form of a pointed, slender, strongly
staining body lying near the nucleus. This body is really somewhat ribbon-shaped,
and more pointed at one end than the other, and it is also somewhat curved, even
in its earlier stages. A transverse section appears crescent-shaped. The nucleus
now elongates slightly and the reticulate structure becomes very conspicuous (plate
2, fig. 25). There are large, strongly stained granules, which are probably composed
of several more or less coherent chromosomes, as the number of these granules is
very much less than the number of chromosomes in the nuclear plate of the dividing
nucleus. The blepharoplast continues to elongate, and in favorable cases the young
cilia can be seen growing from it, but none of my preparations showed the cilia
nearly so plainly as Belajeff’s figures show them in Eqursetum and Gymnogramme.
There is no doubt, however, that the cilia arise in much the same way as Belajeff
describes. ‘The nucleus now becomes indented on one side and assumes a crescent

THE GAMETOPHYTE Di

shape, elongating and also becoming more or less flattened. One end becomes
narrower and sharply pointed, the other remaining thicker and rounded. The
reticulum at this time stains with great intensity and shows a tendency to coalesce,
which in the final stage results in an almost homogeneous, deeply-staining mass,
composed apparently of the completely fused chromosomes. In successful prepara-
tions the nucleus at this stage stains a clear carmine red, in strong contrast to the
bright violet of the blepharoplast. With the complete coalescence of the chromo-
somes the volume of the nucleus is noticeably decreased (plate 1, fig. 19). The
blepharoplast forms a spirally coiled narrow band, from which the cilia can be seen
to grow, following its curve, but the blepharoplast is not in close contact with the
nucleus.

The spermatocytes and the nuclei are rather smaller in Ophioglossum moluc-
canum than in O. pendulum. In the older stages of the spermatozoid, the nucleus
in the former species is decidedly more elongated and more sharply pointed at both

ends (plate 1, fig. 18). In this respect it more nearly resembles the spermatozoids

of Botrychium and those of the true ferns, while in the larger, comparatively short
nucleus, as well as in some other respects, the spermatozoid of O. pendulum is strik-
ingly like that of Equisetum. ‘The number of cilia is large, but the exact number
could not be determined.

Surrounding the spermatozoid and included in its coils is a considerable amount
of cytoplasm. I was not successful in obtaining any living spermatozoids, although
many attempts were made to do this, but in a number of sections of the opened
antheridium some were found in which the spermatozoids had been retained. While
these were usually more or less distorted, some were very well fixed and gave a good
idea of the structure of the free spermatozoid (plate 2, fig. 28). The cilia were
very much distorted in some cases, but in some they were clearly seen. There is
one thick posterior coil mainly composed of the nucleus, which is very much larger
than that of the sperm cell before it 1s discharged from the antheridium. The
nucleus has the form of a slightly coiled thick baade tapering somewhat at both ends,
but more markedly so in front. Beyond this extends a second coil, composed,
apparently, mainly of cytoplasm. ‘This second coil extends into a third much smaller
one, which seems to be a flattened band along whose upper edge the blepharoplast is
closely applied (plate 2, fig. 28). The resemblance of the spermatozoid to that of
Equisetum is very strong, Bur the nucleus is even more shortened than in the latter.

The spermatozoid of Ophioglossum pendulum is larger than that of any Pterido-
phyte that has yet been described. The cytoplasmic envelope and vesicle are not
very clearly separated and probably are similar to those of the free spermatozoids
of O. vulgatum or of Equisetum. Sometimes this protoplasmic envelope completely
surrounds the lower part of the spermatozoid and reminds one somewhat of the
peculiar spermatozoids of the Cycads. Owing to their large size, the spermatozoids
were often sectioned, and in some of the sections the blepharoplast was free from
the body of the spermatozoid and the attachment of the cilia was very easily seen
(plate 2, fig. 29, a).

Mettenius figures the free spermatozoids of O. pedunculosum, but his figures
are certainly not accurate. Bruchmann, who has figured those of O. oulgatumn
(fig. 5, D), shows that they closely resemble the spermatozoids of the true ferns, but
are more massive, and the vesicle which envelops the posterior coils adheres more
closely to the spermatozoid than is usual in the ferns. In these respects it resembles
the spermatozoid of O. pendulum.

Jeffrey examined the development of the spermatozoids in Botrychium vir-
ginianum, which closely resemble those of Ophioglossum. Owing to the method of

28 THE OPHIOGLOSSALES

staining which he employed, the blepharoplast was not clearly evident. I have
examined the developing spermatozoids in this species, using the material which
Professor Jeffrey was so kind as to send me, but employing the double stain of
safranine and gentian violet, which was used in the study of Ophioglossum. While
the differentiation was inferior to that of Ophroglossum, where the material was
fixed with Flemming’s solution, nevertheless the presence of the blepharoplast was
unmistakable.

The spermatocytes are only about half as large as those of Ophroglossum
pendulum, and the spermatozoids correspondingly smaller; hence less favorable
for the study of details. It is evident, however, that the changes in the nucleus and
blepharoplast are essentially the same as in Ophioglossum (plate 2, figs. 34 to 37).
The nucleus, however, becomes much more elongated and the spermatozoids are
more slender, in both of which respects it shows a resemblance to the spermatozoids
of the typical ferns.

The study of the free spermatozoids was confined to those which happened to
have become fixed within the open antheridium and within the venter of recently
opened archegonia. ‘These were in some cases very satisfactorily fixed and stained,
and showed very well indeed the general form of the spermatozoid. The cilia,
however, were not as a rule very well fixed, and while they are evidently numerous
their number could not be made out.

Bruchmann’s figures (fig. 8, D) of the free spermatozoid of Botrychium lunaria
agree closely in form and size with those of B. virginianum. In both species the
vesicle attached to the spermatozoid is more distinct than in Ophioglossum, and
in this respect also the spermatozoid shows a likeness to the true ferns.

THE ARCHEGONIUM.

The archegonium in the Ophioglossacex is very much like that of the ty pical
ferns in its general development. The mother cell of the archegonium, like that of
the antheridium, is first divided by a periclinal wall into an outer cover cell, which
later gives rise to the four rows of neck cells, and an inner cell which, as in the typical
ferns, divides again by a transverse wall into a lower or basal cell and a central cell,
the latter subsequently giving rise to the egg cell and the canal cells. A marked
feature in the archegonium of the Ophioglossacex 1 is the 1 inconspicuous character
of the ventral canal cell, which very often it is impossible to show, and it is possible
that in some cases the ventral canal cell may not be formed at all, although I think
this is doubtful. In general the archegonium i is much alike in the three genera, but
the neck is much shorter’ in Ophioglossum than in Botrychium or Helminthostachys.

THE ARCHEGONIUM OF OPHIOGLOSSUM.

My own studies of the development of the archegonium of Ophioglossum were
based mainly upon a study of Ophioglossum pendulum. Only a very small number of
the young archegonia was secured in O. moluccanum, and so it was impossible to
make a complete study in this species. Lang accurately figures several stages of
the archegonium in Ophioglos sum pendulum, ‘and Bruchmann has described quite
completely its development in O. vulgatum. Bruchmann failed to see the two
nuclei of the neck canal cell which Lang correctly fgures for O. pe ondulum. ‘Vhese
two nuclei are invariably present in both O. pendulum and O. moluccanum, and it
is to be expected that they will also be found in O. vulgatum, as they are constantly
present also in Botrychium virginianum and in all of the ferns that have been
accurately examined. Neither Lang nor Bruchmann saw the ventral canal cell,
which is exceedingly difficult to demonstrate.

THE GAMETOPHYTE 29

In Ophioglossum the young archegonia may be found near the apex of the
prothallial branch, but they may also arise at a considerable distance back of it.
In general, like the antheridia, they arise in acropetal succession.

The mother cell, like that of the antheridium, is sometimes broad, sometimes
narrow and deep, and the cover cell is correspondingly shallow or deep. The first
division of the inner cell takes place shortly after the cover cell is cut off. The next
division is in the cover cell, which first divides by a vertical wall, a second vertical
wall being formed almost immediately, intersecting the first and dividing the cover
cell into Tene practically equal cells, arranged quadrant. wise (fig. 16, 4). The
middle cell next divides by a transverse w all into the primary neck canal cell and
the central cell (fig. 16, F). The canal cell pushes up between the four primary
neck cells, which presently divide by nearly horizontal walls, so that there are two
tiers of neck cells. One or both of these divide again later, so that each row of neck
cells consists of three or four. Rarely there may be five cells in one or more of the
rows

Fic. 16.—Development of the archegonium in O phioglossum pendulum. X180.

A. Transverse section-of gametophyte apex, showing two young archegonia, & , and apical cell, ~.
B-G. Successive stages in the development of the archegonium; seen in longitudinal section; », neck canal cell; b, basal cell.
H. Recently fertilized archegonium; sp, a spermatozoid within the egg nucleus.

The neck canal cell is very conspicuous, its base being broad, and the upper
part narrower and extending to the uppermost neck cells. Whe large and conspicu-
ous nucleus soon divides into two, but as a rule there is no Aimieion wall, although
occasionally two distinct neck canal cells may be present. Sometimes both of the
nuclei remain in the broad basal part of the cell, and sometimes one is at the base
and one nearer the apex. This arrangement seems to depend upon the direction
in which the nuclear division takes place.

The basal cell divides by a vertical wall at about the same time that the primary
canal cell is cut off from the central cell. The basal cell subsequently undergoes
further divisions, but its limits are readily distinguishable up to the time that the
archegonium is mature (fig. 16, G).

In its earlier stages, the archegonium of Ophioglossum pendulum bears a
striking resemblance to that of the Wintatracess which the mature archegonium
more nearly resembles than it does that of Botrychium. According to Banchinanit s
account, O. vulgatum has a neck somewhat longer, and this is also true of O. moluc-
canum. Even when mature, the neck projects but little above the surface of the
prothallium, although there is some elongation of the cells at the time of dehiscence
(fig. 16, G).

The ventral canal cell is very difficult to demonstrate, and one is sometimes
inclined to doubt whether it is formed at all in some cases; neither Lang nor Bruch-

30 THE OPHIOGLOSSALES

mann was able to detect it in O. pendulum and O. vulgatum. Itis probable that
its apparent absence in most of the archegonia is due to the fact that it is formed very
late and is extremely inconspicuous. “Che same apparent absence of a ventral canal
cell in the Cyeads and some Conifers has been shown, on more critical study of the
material, to be due to the small size of the ventral nucleus and to its very evanescent
character, In nearly all of the archegonia examined, just before they opened there
was present a vesicular body above the egg, which was probably the ventral canal
cell much distended with fluid preparatory to the opening of the archegonium. A
small nucleus, or what looked like one, could sometimes be seen, but it must be said
that its nuclear nature was not above suspicion (plate 2, fig. 33).

Just before the archegonium is ready to open, the egg cell, which up to this
time is compressed above by the basal wall of the neck canal cell, becomes distended
and pushes up the base of the canal cell, which thus becomes concave below. It is
probably about this time that the ventral canal cell is cut off. Unfortunately, no
cases were found showing mitosis in the central cell, but there seems no good reason
to doubt that a ventral canal cell is, usually at least, cut off.

Fic. 17.—Development of the archegonium in Botrychium virgintanum.

A-D. Longitudinal sections. 320.
E. Ripe archegonium, showing ventral canalcell v. 165. (After Jeffrey.)
F. Recently fertilized archegonium, showing spermatozoids within venter. 320.

The neck canal cell does not show the complete disorganization which is com-
mon, but retains its form up to the time that the archegonium opens. With the
opening of the neck there is some elongation of the outer neck cells, but there is
decidedly less projection above the surface of the prothallium in O. pendulum than
is the case in O. vulgatum. The nucleus of the egg cell is large, but it does not always
stain readily, except the nucleoli, and it may be that the same resistance to stains
is the reason why its sister nucleus in the ventral canal cell is so difficult to see.

THE ARCHEGONIUM OF BOTRYCHIUM.

The archegonia in Botrychium are found usually upon the flanks of the median
ridge, upon whose summit are borne the antheridia. In their early stages they
closely resemble those of Ophioglossum (fig. 17). As in the latter, there is some
variation in the form of the mother cell, which may be quite deep and narrow, or
relatively broad and shallow. The subsequent divisions in the central cell and in

THE GAMETOPHYTE 31

the cover cell agree very closely with those in Ophioglossum; but the neck cells are
more numerous and at maturity the neck projects much more strongly than 1s the
case in Ophioglossum. ‘There may be as many as seven or eight cells in each row
of the neck, which, except that it is quite straight, resembles that of the typical
ferns. It is especially like that of Osmunda, in which the neck is also straight. The
neck canal cell (fg. 17, D) becomes much elongated, and the nucleus divides, as in
Ophioglossum, but in most cases at least there is no division of the canal cell itself.

As in Ophioglossum, the ventral canal cell is very inconspicuous, and often
impossible to detect. Jeffrey (fg. 17, E) figures a very evident ventral canal cell,
but the nucleus is much smaller than that of the egg or neck canal cell. I have also
found what seemed to be a ventral canal cell in the archegonium shortly before it
opened, but, as in the case of Ophioglossum, this was not absolutely certain. As
in the corresponding stage in Ophioglossum, above the egg cell, with its large and
conspicuous nucleus, eed is a clear space containing a eaall round body, which
showed no evident nucleolus, but otherwise stained very much like the nucleus of
the egg, and was probably the nucleus of the ventral canal cell (fg. 17, D, v.)
While no certain cases of mitosis of the egg nucleus for the cutting off of the ventral
canal cell were encountered, in one case the egg nucleus looked as if it were in the
early prophase of division. Bruchmann’s fioures of the archegonium of Botrychium
lunarta closely resemble that of B.virgintanum, but he was unable to find a ventral
canal cell, nor did he apparently see the division of the nucleus of the neck canal cell.
The archegonium of Helminthostachys(fig.11,D) closely resembles that of Botrychium.

FERTILIZATION.

In only a few cases were spermatozoids seen within the neck and venter of the
open archegonium in Ophioglossum, but twice a spermatozoid was seen within the
nucleus of the egg; as there were no other stages obtained, however, the details of
nuclear fusion could not be followed (fg. 16, “H). The spermatozoid penetrates
the nucleus of the egg, where for a time it can be seen distinctly. It 1s probable
that its fusion with the egg nucleus is much like that described by Shaw for Onoclea
(Shaw 1, 2). In the mature egg cell the nuclear reticulum is often decidedly con-
tracted, but whether this is normal or the result of reagents can not be said.

FERTILIZATION IN BOTRYCHIUM VIRGINIANUM.

Jeffrey observed a single spermatozoid within the venter of the archegonium
and noted that at the time of fertilization the egg developed what he called a
“receptive prominence.” I have observed the same phenomenon in several cases
(plate 2, fig. 46), and in a good many instances have also found one or more sper-
matozoids within the venter. In one case, what looked very much like a sperma-
tozoid was seen within the egg nucleus itself, and the process of fusion is probably
very much the same as that so fully described by Shaw for Onoclea. In the specimen
shown in fig. 17, F, one of the spermatozoids looks as if it has partially penetrated
the egg, but it is impossible to be certain that it was not simply lying against it. In
this case, just above the nulceus of the egg there was a slight break in The granular
cytoplasm that looked as if it might be a receptive spot, but the spermatozoid was
not entering the egg at this point.

In another instance a curious thing was noted, but whether it was normal
or not it is impossible to say (plate 2, fig. 46). A spermatozoid had just entered
the neck of the open archegonium and the egg had developed a very conspicuous
receptive prominence. The nuclear contents were very strongly contracted and
deeply stained and a portion apparently projected beyond the nuclear membrane

32 THE OPHIOGLOSSALES

into the receptive prominence. A similar synapsis was noted in several cases. In
most instances where free spermatozoids were present in the venter of the arche-
gonium the egg nucleus presented a curious appearance (plate 2, figs. 47, 48). A
single large nucleolus was present, but scattered through the nucleus there were
sometimes a dozen or more of intensely staining round bodies, which at first sight
looked like nucleoli, but on more careful examination were seen to differ from
the large nucleolus in that they appeared less homogeneous and generally showed a
central vacuole-like structure. These granules stain very much like the body of
the spermatozoid, and it was thought that possibly they might be derived from a
fragmentation of the body of the spermatozoid that had entered the nucleus, but
this could not be satisfactorily demonstrated and the nature of this phenomenon
must remain for the present uncertain.
Fertilization in Helminthostachys has not been observed.

SIGNIFICANCE OF THE ENDOPHYTE.

That the presence of the endophyte is essential to the existence of the sapro-
phytic gametophyte of the Ophioglossacex is indicated by the failure of the germi-
nating spores to develop unless they become associated with the fungus. Moreover,
the universal occurrence of a similar endophyte in all humus saprophytes among
the seed plants indicates that in all of these chlorophyll-less plants the presence of the
fungus is necessary for the existence of the host. Although it has not been directly
proved, it is generally assumed that one réle of the endophyte is the elaboration of
some of the carbonaceous constituents of the humus. The infrequent communica-
tion between the external hyphae and the internal mycelium makes it unlikely that
the nutritive products are directly absorbed by the fungus, and it seems much more
probable that the rhizoids of the gametophyte are the direct agents of absorption.
How the humus constituents are changed by the action of the fungus so that they
are available for the cells of the host is not clear, and it is by no means impossible
that some at least of the necessary carbon may be derived from the fungus itself,
in the digestive process to which it is subjected in the cells of the host. This seems
plausible from the fact that in the green prothallia of certain ferns, where presumably
the gametophyte is entirely able to supply its own carbon compounds through
photosynthesis, these digestive cells appear to be wanting; at any rate they were not
observed in a number of forms that I have studied.

The experiments of Ternetz (Charlotte Ternetz 1), show that certain fungi,
including endophy tic mycorrhiza, are able to assimilate free nitrogen and confirm
the assumption of earlier observers that the fungus is useful to the host in supplying
it with nitrogen compounds; but, while this is probably a very important part of
its hinctions it seems to me that it is not perhaps the only one, and that the carbon
also is supplied, directly or indirectly, through the agency of the fungus.

In an extended study of the endophy tic mycorrhiza of the saprophytic orchid,
Neottia, W. Magnus (W. Magnus 1) has shown that two types of mycelium ex-
hibited by the endophyte are of very different nature. The slender, cylindrical
hyphee constitute the active portion of the fungus, which behaves like a parasite
toward the cells which it invades, destroying the weareh and probably other constitu-
ents of the cells, but not attacking the naelens: The swollen vesicular mycelium,
however, is a degenerating structure and is itself destroyed by the cells of the host,
which actually digest dhése fungus mycelia in much the same way that the cells of
the leaf of Deotera digest their prey. Magnus has very graphically shown that the
relation of the two symbionts is mutually antagonistic, each one acting as a parasite
on the other; nevertheless the presence of the fungus is essential to the higher

2

THE GAMETOPHYTE 33

organism, so long as the latter is destitute of chlorophyll. The explanation of the
widespread saprophytism exhibited by so many of the higher plants may be sought
in this attempt to defend themselves against what was probably at first a strictly
parasitic organism. Having acquired the power to attack and to feed upon the
parasite, the photosynthetic “functions were more and more subordinated, until a
state of true parasitism (or saprophytism) resulted. The numerous semi-saprophytes
like most of the green Ericales and many of the green Orchidacex, are good examples
of transition stages, while the characteristic leafless humus saprophytes, such as
Monotropa and Corallorhiza, represent the fully developed phase of this peculiar
form of symbiosis. We might say that such green prothallia as those of the Marat-
tiacee and Gleichenia, which contain an endophytic fungus, bear somewhat the
same relation to the subterranean prothallia of the Ophioglossacee that the green
Ericales do to Monotropa.

The occurrence of a similar endophyte has also been noted in a number of
liverworts. Cavers (Cavers 1) has studied this association with some care in the
common liverwort, Fegatella, as well as in some other Hepatica. He found
Fegatella that the endophyte is beneficial to the growth of the host, which was more
vigorous when the fungus was present. He assumed that this was due to the assist-
ance given by the fungus in the assimilation of organic matter from humus or other
organic substrata. (See also Humphrey 1).

This occurrence of an endophyte in the Hepaticae makes its occurrence in the
green prothallia of ferns readily comprehensible. Whether in the latter it is an
advantage to the host to have the endophyte present remains to be seen, but it
is highly probable that such is the case. Once having acquired the habit of
associating itself with the fungus, the gradual evolution of the purely saprophytic
subterranean gametophyte of the Ophioglossacee from green forms similar to those
of the Marattiacez is readily comprehensible.

w

34 THE OPHIOGLOSSALES

Il. THE EMBRYO.

The development of the embryo in the Ophioglossacez has been more or less
completely studied in Ophioglossum pedunculosum, O. vulgatum, O. moluccanum,
O. pendulum, Botrychium uirginianum, B. lunaria, and B. obliquum (Mettenius 1,
Bruchmann I and 2, Lang 1, Campbell 8, Jeffrey 1, Lyon 1).

The first division in the young embryo in all of these is usually approximately
transverse, although there may be a good deal of variation in this respect. It is; ~
probable that in all cases the primary root, the stem apex, and the foot all arise from .
the epibasal region. The embryo reaches a very large size before the root emerges
from the overlying prothallial tissue and all of the organs of the young sporophyte
are very late in developing, so that it is not easy to trace their origin back to the
early cell divisions in the young embryo. Much the most conspicuous organ of the
young sporophyte is the root, which may reach a very large size and an advanced
stage of development before any evidence of the other organs is apparent. Indeed,
several roots may be developed before the shoot is established. In Ophioglossum
vulgatum and Botrychium lunarta, according to Bruchmann’s account, the young

Fic. 18.—O phtoglossum moluccanum.

A. An old archegonium. 180.
B. Two-celled embryo within the archegonium. X18o.
C. Two sections of an older embryo. X18. cot, cotyledon; f, foot; r, root.

sporophyte remains several years under ground before the first green leaf appears
above the earth, and it is probable that in Ophioglossum pendulum there is also a
long period of underground existence before the first green leaf is developed. In
Ophioglossum moluccanum, however, and in Botrychium virginianum, the first
leaf developed is a green foliage leaf, which grows rapidly and soon appears above
the surface of the ground.

THE EMBRYO OF OPHIOGLOSSUM.

The first figures that we have of the embryo of Ophioglossum are those of
Mettenius, but his figures of the embryo of O. pedunculosum are not at all satis-
factory, although he shows correctly sections of the older sporophyte. Lang figures
only one embryo, a somewhat advanced one of O. pendulum. Bruchmann figures a
two-celled stage and a single more advanced embryo of O. vulgatum, but he describes
and figures several stages of the young sporophyte. My own study of Ophioglossum
was based mainly upon the development of the embryo in O. pendulum, where a

THE EMBRYO 315)

fairly complete series of embryos was obtained and the development followed quite
satisfactorily.

In O. moluccanum | fond two quite young embryos, the youngest consisting
of two cells (fig. 18, B), the other much more advanced, with the cotyledon already

differentiated and the beginning of the primary root recognizable. In the first

embryo the basal wall was nearly transverse to the axis of the archegonium and, to
judge from the arrangement of the organs of the older embryo, it looks as if the whole

of the hypobasal region formed the foot, the epibasal half giving rise to the cotyledon |

and root. The older embryo (fig. 18, C) was cut longitudinally in the plane of the
cotyledon, which at this time comprises pretty much the whole of the upper part of
the embryo, the hypobasal region being occupied mainly by large cells which con-
stitute the foot. Unfortunately, 1 in this series the section containing the apex of the
leaf was missing, and so it is impossible to say whether at this stage a definite apical
cell is present in the cotyledon; but, as in somewhat older stages ‘such a cell seemed
to be always present, it is probable that there was an apical cell in the cotyledon of
the embryo in question. At the base of the leaf, and almost in the center of the
embryo, there was a group of actively growing cells, evidently marking the position
of the root apex, which arises deep in the tissue of the embryo, very much as we
shall see to be the case in the Marattiacee; and it seems probable that in O. moluc-
canum, as in Danea, the root grows downward through the foot and in a direction
coincident with the axis of the young cotyledon.

Fic. 19.—O phioglossum vulgatum (after Bruchmann).

A. Median section of a young embryo. X160. B. An olderembryo. 25.
C, D. Older embryos, showing beginning of apical bud, b; r, root. X25.

The cotyledon grows upward and soon ruptures the overlying prothallial tissue,
while the root grows down in the opposite direction and pierces the prothallium at a
point some distance below where the leaf emerges. As the root grows downward
through the foot the latter becomes unrecognizable, its outer cells remaining,
however, as a zone of large cells encircling the equatorial region of the very much
elongated bipolar embryo.

The young root very early develops a tetrahedral apical cell, like that of the
later roots. This cell is probably cut out from the central tissue of the embryo, close
to the base of the leaf. The cell r in fig. 18, C, to judge from its position and the
arrangement of the cells around it, is probably the initial cell of the primary root.

The young cotyledon grows rapidly and has first a conical form (fig.'23) BY;
terminating in a definite apical cell. As it grows it develops a small oval lamina
and a slender petiole, and presently the little green leaf appears above the surface
of the earth.

The embryo of O. vulgatum differs remarkably from that of O. moluccanum in
the late development of the leaf. Bruchmann was unable to obtain the younger
stages of the embryo, so that the origin of the different members is still somewhat
obscure. In this species it is the root which develops first, and it soon becomes

36 THE OPHIOGLOSSALES

exceedingly conspicuous. Bruchmann considers that the root and foot are both of

hypobasal origin, but he bases this on a comparison with the true ferns rather than

upon actual study of embryos, as he was unable to obtain embryos sufhciently young

to demonstrate this, and all trace of the original divisions disappears before any

sign of the stem and leaf is evident. It may be well questioned whether, as in |
Botrychium and O. pendulum, the foot does not take up the whole hypobasal region.

It is not impossible that the position of the basal wall may also vary in O. vulgatum.

‘From a comparison with the embryo of O. pendulum, | am inclined to assign more

of the embryo of the former to the foot region than is done by Bruchmann.

In O. wulgatum there is, finally, a differentiation of the stem apex from the
epibasal region, as in Botrychium and the true ferns, while in O. moluccanum there
is no trace of a stem apex in the very young sporophyte, this developing later as a
bud upon the first root.

From a study of Ophioglossum moluccanum and also of O. pendulum it is
evident that the history of the young sporophyte in these species differs strikingly
from that of the other Pteridophytes. In both of these species the definitive sporo-
phyte always arises secondarily, as a bud upon the root, in the same way that
adventitious buds are commonly formed upon the roots of the adult sporophyte.
Bruchmann notes in O. vulgatum the very precocious development of the primary

Fic. 20.—0 phioglossum pendulum.

="

. Transverse section of very young embryo. 180.

. Longitudinal section of young embryo. 180.

. Three transverse sections of an older embryo; 1-1, basal wall; r, primary root. 180.
D. An older embryo; r, primary root.

QAwW>

root and the late appearance of the stem apex and first leaf; but in this species the
shoot apex, according to his statement, is derived directly from the epibasal half of
the embryo, as it is in most Pteridophytes.

In Ophioglossum pendulum, where the development of the embryo seems to
offer no check to the further growth of the prothallium, the position of the arche-
gonium varies a good deal and it is impossible to tell from a section just what the
position was in the living state, as the branches of the gametophyte extend in all
directions and archegonia may be formed at any point upon their surface. To
judge from the youngest stages of the embryo that were met with (fig. 20), the basal
wall in this species is not necessarily transverse. In both of the cases figured it
was oblique, and more nearly longitudinal than transverse. It is likely, however,
that it is horizontal, or approximately so. In the four-celled embryo shown in
fig. 20, 4, the quadrant walls were at right angles to each other, and this was also
the case in the five-celled embryo shown in fig. 20, B. Somewhat older embryos (C)
show that there is a pretty regular octant formation, and Bruchmann states that
this is also the case in O. vulgatum.

While in the typical ferns, and in Botrychrum, all of the organs of the young
sporophyte can be traced to certain regions of the young embryo, in Ophioglossum

THE EMBRYO 37

pendulum only one of the definitive organs, the root, arises in this way, and this
becomes differentiated at a very early period. One of the octants next to the arche-
gonium at once becomes the apical cell of the young root. This cell is very soon
recognizable by its size and shape, and quickly begins its regular segmentation.
The primary cap-cell is soon cut off (fig. 20, D), and from now on the young root
is very conspicuous. The octant divisions are very clearly marked in this case,
and in section 3, which is the uppermost of the three, the large triangular apical
cell of the root is very evident.

Two types of the embryo were seen in this species. One of these (fig. 21, 4)
is nearly globular in form, the other (fig. 21, B, C) is elongated. The former looks
as if it originated from an embryo in which the basal wall was transverse to the axis
of the archegonium, in the other it was probably more or less vertical. It is probable
that in the former instance the root initial is one of the epibasal octants, while the
whole of the hypobasal portion gives rise to the large foot. In the second type it is
difficult to say which half should be considered epibasal and which hypobasal, but,
as in the other case, one half may be considered to be root, the other half foot, the

Fic. 21.—O phioglossum pendulum. Older embryos.

. Vertical longitudinal section; f, foot; r, primary root.

- Horizontal section. X75.

+ Older embryo, with single root.

. Embryo with two roots; pr, gametophyte. Shaded region occupied by the mycorrhiza.

gaws

growth of both being nearly in a plane at right angles to that of the archegonium
axis, and; suggesting the relative positions of cotyledon and foot in the embryo of
Ophtioglossum moluccanum.

In form the first type somewhat recalls the embryo of Botrychium virginianum.
The whole lower portion, or hypobasal half, forms the very conspicuous foot, while
from the epibasal region the primary root is developing, and already the rudiment
of the second root is visible. Whether the latter arises directly from the primary
root, or whether it arises independently from the second epibasal quadrant, is not
quite certain. The cells of the epibasal region are evidently actively growing, having
- abundant protoplasm and conspicuous nuclei. The cells of the foot are larger and
much more transparent.

The second type of embryo (fig. 21, B, C) resembles very closely the second
state of the embryo of Ophioglossum vulgatum, where, as is said by Bruchmann,
the embryo is “all root.”

38 THE OPHIOGLOSSALES

In O. moluccanum the prothallium probably lives for a single season only, and
the formation of the sporophyte stops its further development; but in O. pendulum,
where embryos are much less frequently found, the large gametophyte continues
its growth apparently unchecked by the development of the attached sporophyte,
which retains its connection with the gametophyte for a very long time, as in O.
vulgatum and Botrychium virginianum.

The embryo reaghes a very large size before it breaks through the prothallium.
The primary root then emerges as a conical point (fig. 3, /, sp). The second root
remains short for a time. There seems to be a good deal of difference as to the time
of the appearance of the latter. In the globular type of embryo the second root
appears very early, and it looks as if it might have been formed quite independently
of the primary root. Sometimes, however, the primary root may attain a length of
several centimeters, and may even begin to form rootlets before the second root
emerges; while in other cases the two roots grow in opposite directions and seem to
be of about equal size (fig. 3, £).

The leafy shoot in Ophioglossum pendulum
does not appear until the root system is well
advanced. The primary root, although attaining
a length of 10 centimeters or more, in no cases
showed any signs of leaf-bearing buds in the
specimens that I collected. Rootlets were devel-
oped in some cases, and it is not impossible that
there may be an extensive development of the
root system before the first leafy bud is formed.
This is quite in harmony with the large develop-
ment of the roots in O. vulgatum, where Bruch-
mann believes that it may be eight or ten years
before the first foliage leaf appears above the
ground. In O. vulgatum, however, this leaf arises
from the original stem apex derived directly from
the embryo, and not from an adventitious bud.

Ophioglossum moluccanum and the similar
species that grow with it differ very much from
Ophioglossum pendulum in the character of the

Fic. 22.—0O phioglossum moluccanum.
A. Median section of young sporophyte before YOUN sporophyte, which, as we have seen, at once

formation of bud; /, cotyledon; r, root. develops a green foliage leaf or cotyledon. The

pr, the gametophyte. X15. 2
B. Central region of same, more enlarged; tr, sporophyte very closely resembles that of O. pedun-

___ first tracheids. culosum described by Mettenius; in fact, the
C. An older sporophyte, showing bud, 6, de- : :
colegio Hock wieiily case’ Saree resemblance is so close that it would seem to
D, E. Lamina of cotyledon, showing venation. confirm the close relationship of this spectes and
: possibly its identity with some of the forms asso-
ciated by Raciborski under the name O. moluccanum (Raciborski 1).

As Mettenius correctly showed in O. pedunculosum, the first organ to be
developed is the cotyledon, which soon pierces the earth and appears as a green
foliage leaf. This primary leaf is continued directly into the primary root, but no
stem apex is developed, nor is any sheath formed about the leaf base in the young
sporophyte, which consists practically of leaf and root alone. The latter often
penetrates for some distance into the prothallial tissue before it emerges, so that the
central portion of the young sporophyte is surrounded by a sheath formed by the
prothallial tissue. A longitudinal section of the sporophyte (fig. 22, 4) shows that
the tissues of the leaf are continued directly into those of the primary root. A

3

THE EMBRYO 39

single axial vascular bundle traverses the whole of the young sporophyte without
interruption, and there is no recognizable boundary between the tissues of the leaf
base and those of the root. The central region of the embryo is somewhat thicker
and its outer cells are enlarged, these outer cells probably belonging to the foot
through which the root has penetrated and which at this period can not be clearly
recognized. The strictly bipolar character of the young sporophyte and the way
in which it perforates the gametophyte resemble most nearly the corresponding
stages of Equisetum and the Marattiacee, and it may be said that Lyon’s recent
studies on Botrychium obliquum indicate that in this species also there is a similar
bipolar arrangement of leaf and root.

Mettenius pointed out in O. pedunculosum that the definitive sporophyte arises
as an adventitious bud upon the primary root, either close to the leaf base or, more
commonly, at some distance from it. This is also the case in O. moluccanum and
the other allied species. In one case observed by me two independent sporophytes
were found growing from the same prothallium, but this is unusual, and in most of
the cases where two sporophytes seem to be present, one of these is really the sec-
ondary sporophyte growing from the primary root.

Fic. 23.—O phioglossum moluccanum.
A. Young cotyledon, longitudinal section; pr, gametophyte. 8o.
B. Apex of cotyledon more highly magnified; x, apical cell.
C. Young sporophyte in which a rudimentary second leaf (/*) is present. X80.
D. Cross-section of apex of primary root. 200.

While in O. vulgatum the sporophyte stays under ground for several -years,
in O. moluccanum there is every reason to believe that there is only a brief interval
between the first formation of the leaf and its appearance above ground. The small
size and the character of the gametophyte, as well as the quick germination of the
spores and the rapid growth natural to a tropical climate, indicate that the gameto-
phyte is an annual and that it dies as soon as the young sporophyte is established.

In O. pendulum the primary root as it breaks through the prothallium elongates
rapidly, but just how far it grows before the bud 1s formed upon it could not be
determined. ‘These roots are very brittle and easily broken off, and in no cases were
young buds found upon roots which were still connected with the prothallium. The
first root sometimes reaches a length of 3 or 4 centimeters before the second root can
be seen at all. The growth of the roots in the young sporophyte is in all respects
like that occurring in the older ones. There is a large tetrahedral apical cell, the
divisions of which are quite regular, and the conspicuous axial vascular cylinder is

40 THE OPHIOGLOSSALES

developed at an early period. The stele of the second root joins that of the first
where the latter joins the foot (fig. 21, D). The primary root in O. pendulum is,
usually at least, diarch.

DEVELOPMENT OF THE PRIMARY BUD IN OPHIOGLOSSUM MOLUCCANUM.

The several terrestrial species of Ophioglossum growing at Buitenzorg and
associated under the name O. moluccanum differ strikingly from O. vulgatum in the
further history of the young sporophyte as well as in the early development of the
first functional leaf. This difference is also found in the young sporophyte of O.
reticulatum (?) collected at Hakgala in Ceylon. All of these tropical species agree
with O. pedunculosum, which was correctly described by Mettenius (Mettenius 1),
in the origin of the definitive axis which arises as an adventitious bud from the
primary root of the young sporophyte. A similar condition of things probably is
true also in O. pendulum, although in the latter no leaf is at first developed from the
young sporophyte, which is composed exclusively of one or two roots in addition to
the foot, so that the first leaf in O. pendulum is also an adventitious structure.
Whether or not the primary leaf in O. pendulum, and probably at the same time the
stem apex, arises as a bud from the primary root, or whether (which seems more
likely) it is developed from a secondary root, can not be stated, as no young leafy
buds were found in connection with the gametophyte.

Fic. 24.—O phioglossum moluccanum.

A. Tangential section of primary root, showing young, endogenous bud, 5. about so.
B.C. Two sections of the same bud. B, the first leaf; C, stem apex. X150.
D. Two transverse sections of a young bud; 1 passes through stem apex st; 2, through leaf.

Mettenius gives no detailed study of the development of the bud upon the root,
nor does he state whether he recognized its endogenous origin. ‘The bud arises.
much in the same way that a secondary root does, and is not visible upon the out-
side of the root until it is far advanced in its development, the young leaf breaking
through the overlying tissues in much the same way that a young root emerges. In
two instances the rudiment of the young bud could be seen close to the apical
meristem of the root, in a position which is exactly the same as that described for the
leafy buds formed at the apex of the root in O. vulgatum. More commonly, the
bud originated nearer the base of the root, but it may arise at any point between
the base and the apex. Figure 24 shows sections of the youngest buds that were
found. 4 is a tangential section of the primary root, in which the young bud has
formed at a point not very far back from the root apex, r._ The first leaf of the young

THE EMBRYO 41

bud and the young stem apex can already be recognized, and these have apparently
developed quite independently of each other. The leaf rudiment, B, lies nearer the
bundle of the main root and may perhaps have taken its origin from a single endo-
dermal cell, but this could not be certainly determined. The young leaf soon forms
a slightly projecting conical body, composed of a few cells with conspicuous nuclei,
separated from the adjacent root tissue by a small’space. At this stage it is not quite
clear whether the apical cell has been developed, but later stages show the presence
of an unmistakable apical cell of approximately tetrahedral form. Lying nearer
the periphery of the root is the young stem apex, composed of a small group of
meristematic cells, one of which is unmistakably the initial cell for the stem. This
apical cell is truncate below and the base is broader than the outer free face. Above
the stem apex can be seen the cavity which separates the outer tissues of the young
bud from the cortical tissue of the root.

Fig. 24, D, shows two transverse sections of a bud of about the same age as the
one just described. No. 1 passes through the stem apex and shows the conspicuous
triangular apical cell, No. 2 shows a section of the leaf above the level of the stem
apex with the basal tissue of the leaf extending around the stem region. ‘This is the
beginning of the hollow stipular sheath which incloses the stem apex of the bud and

Fic. 25.—O phioglossum moluccanum.

. Bud about to break through primary root; /, first leaf; st, stem apex. X about 80.

. Apex of leaf more highly magnified.

. Transverse section of a young bud passing through base of leaf,/. Xr150.

. Section of same passing through stem apex, x.

. Transverse section of stem apex from an older sporophyte. The apical cell is four-sided.

mBoOwS

which is so conspicuous a feature in the stem apex of the older sporophyte. Probably
the large central cell in the section of the leaf shown in No. 2 is the apical cell, but
this is not quite certain.

A transverse section of a somewhat older bud (fig. 25, C) shows a narrow cleft
at the base of the leaf in front, opening into a cavity within which the stem apex lies.
It is impossible to say exactly how much of this stipular sheath really belongs to the
leaf base and how much is derived directly from the adjacent cortical tissue of the
root, since the tissues of the leaf base merge insensibly into the latter. From this
time on, each new leaf develops this conical stipular sheath, which incloses the stem
apex and the next youngest leaf, and which has so often been described in the older
sporophyte.

If a median section of the young bud is examined just before the bud breaks
through the overlying tissues of the root (fig. 25, 4), it can be clearly seen that the
leaf, which now has the form of an elongated cone, lies above the level of the young
stem apex, and by this time the differentiation of the vascular bundle of the leaf is
well advanced. This bundle connects with the vascular bundle of the primary root

42 THE OPHIOGLOSSALES

and there is no connection between it and the tissues of the stem apex of the bud.
The latter consists of a shallow mass of tissue with the conspicuous apical cell in
the center, but below it there is no sign of the development of any procambium.
The stem apex lies in a depression formed by a shallow ridge, which encircles it
and forms the beginning of the stipular sheath belonging to the base of the leaf.
The exact limits of the basal tissue of the leaf, as we have already stated, can not
be clearly defined. The cavity above the stem apex is still very evident, but how
much of the tissue lyi ing above the cavity belongs to the leaf base, and how much to
the cortical tissue, is not clear. The section through the apex of the leaf (fig. 25, B)
shows a single large terminal cell which, without doubt, is the apical cell.

The young bud is now ready to emerge and, very soon after, the rapidly elongat-
ing apex of the young leaf pushes through the outer root tissue and emerges upon
the outside. The stem apex remains buried within the root tissues and the sheathing
base of the leaf. The leaf base is surrounded by a ragged sheath, formed by the
ruptured outer tissues of the root.

The development of the bud upon the root in O. pendulum unfortunately could
not be followed. The smallest leaves found were 10 centimeters or more in length,
and, although these were probably the primary leaves, they were not recognized as
such at the time the plants were collected, and so there was no opportunity of tracing
their connection with the original root.

The fully developed cotyledon in what may be considered the typical form of
QO. moluccanum is more or less lanceolate in outline (fig. 22, D). There is a central
vein from which branch secondary veins on either side, connecting with the central
vein by anastomosing branches which inclose elongated meshes. In the form with
broader leaves, probably another species, the mid-vein is more obscure and the
meshes are broader and more numerous.

Three types of the embryo may be recognized in Ophioglossum, represented
respectively by O. moluccanum, O. vulgatum, and O. pendulum. If, as seems not
unlikely, O. moluccanum is the most primitive of the three, some interesting points
arise as to the significance of the peculiarities exhibited by the embryo, which shows
only two organs aside from the foot, viz, the cotyledon and primary root, these
growing in an almost exactly opposite direction, without any clear line of demarca-
tion between them. I have ventured to draw a comparison between the sporophyte
of Ophioglossum and that of Anthoceros, assuming that the former has arisen from
some bryophytic type not unlike Anthoceros, by the development of a root from the
base of the sporogonium and of a special foliar organ from the basal meristem of
such a sporogonium. The embryo of O. moluccanum approaches this hypothetical
form, as it consists only of leaf and root, and no stem apex is developed from it,
its growth being of limited duration. In this case the definitive sporophyte is a
secondary structure developed as a bud upon the primary root. In O. vulgatum,
however, the definitive stem apex, although of very late origin, is apparently a
product of the original embryonic tissue, but the first foliage leaf is of much later
origin. In O. pendulum the formation of the leafy sporophyte is also secondary,
but neither stem apex nor leaf is developed from the embryo itself.

If, as the writer believes, Ophioglossum represents the most primitive type of
the fern series, it is quite conceivable that in O. moluccanum and its allies the embryo
represents the condition existing in the ancestral type from which these have sprung.
On the supposition that the leafy sporophyte is derived from a large bryophytic
sporogonium resembling that of Anthoceros, there must have been a _stage when the
sporophyte consisted of two parts only, the upper sporogenous portion, which later
developed into a sporophyll, as represented in Ophioglossum, and the root. Of

bo]

THE EMBRYO 43

course, it is quite possible that the peculiar origin of the definitive sporophyte in
O. moluccanum and O. pedunculosum is secondary, but this is by no means neces-
sarily the case. However, it seems highly probable that the extraordinary develop-
ment of the roots in O. vulgatum and O. pendulum and the protracted subterranean
life in these species constitute a secondary phenomenon associated with the pro-
nounced saprophytic life of the gametophyte.

The apex of the shoot lies in a narrow depression between the base of the leaf
and a narrow ridge which extends around it on the side opposite the leaf base. This
ridge is the beginning of the conical sheath characteristic of the shoot apex of the
older sporophyte. A transverse section of the young apex at about this time shows
that the apical cell is triangular in outline.

The first root of the young bud does not emerge until the leaf is nearly complete.
From this time on the further growth is due to ine activity of the stem apex, from
which new leaves and roots presumably are developed in the same way as in other
species that have been studied. How long it is before fertile leaves are formed was
not ascertained, but in the rapidly growing species of a tropical climate it is likely
that this takes place before long. The occurrence of very small fertile individuals

(fig. 55, B) points to this.

THE EMBRYO OF OPHIOGLOSSUM VULGATUM.

The embryo of O. vulgatum (Bruchmann 1) differs from that of both O.
pendulum and O. moluccanum in its development, but in the earlier stages it closely
resembles the former species. As in O. pendulum, the root is the first organ to be
developed and it reaches a large size before there is any indication of the formation
of a stem apex or cotyledon. Bruchmann states that the root apex arises from the
hypobasal half of the embryo, but his figure (fig. 19, 4) of the young embryo, where
the root apex is just visible, closely resembles a corresponding stage in O. pendulum,
where the root is certainly of epibasal origin; and, to judge from the elongated form
of the two-celled embryo which Bruchmann figures, one tis inclined to Bales that
the basal wall ts really at right angles to the long axis of the embryo, and not parallel
with it, as he figures, so that the whole of the hypobasal part might be interpreted
as the foot, while the root would be of epibasal origin, as it is in 0. pendulum.

The next stage figured by Bruchmann (fig. 19, B) is very much like the type of
Q. pendulum, where only one root was developed at first, and in this case also we are
inclined to consider the whole of the enlarged base of the embryo as the foot.

Before the cotyledon and stem apex can be recognized the first tracheary tissue
of the root has already been developed, and about the same time the apex of the
second root can be seen arising near the base of the primary root (fg. 19, C).

The cotleydon arises near the base of the root, upon the upper side of the
embryo, and forms a small conical protuberance, which grows from a definite apical
cell. At the base of the cotyledon, on the side turned away from the root apex, a
shallow depression is formed, and in this there may be seen a single large superficial
cell, which is apparently the apical cell of the very limited stem apex. Inclosing the
cotyledon and the stem apex is an elevated ridge which grows up about them and
finally forms a sheath, which rapidly grows so as to include the bud within a cavity
completely closed except for a narrow canal which opens outward.

While the cotyledon and stem apex are thus formed from superficial tissue in
O. vulgatum, their early inclosure in the sheath suggests that we have to do with a
condition intermediate between the completely endogenous shoot apex in O. moluc-
canum and the entirely exogenous shoot in Botrychium.

44 THE OPHIOGLOSSALES

The second root arises quite independently of the stem apex, being developed
below the insertion of the primary root, and its vascular bundle joins that of the
first root near its base.

A rudimentary vascular bundle is developed within the cotyledon, and also
joins the bundle of the main root near its base, but no bundle at all is developed
within the stem. ‘The cotyledon reaches only a very small size, but the second leaf
soon appears nearly opposite the cotyledon.

The second leaf also develops at an early period a vascular bundle, which
connects with the vascular bundle of the primary root near its point of junction with
the second root, and this exactly resembles the arrangement of the bundles in the
bud formed upon the root in O. moluccanum. It is evident that in the young sporo-
phyte of O. vulgatum, as in O. moluccanum, the vascular system is made up entirely
of the bundles of the roots and leaves, the stem itself having no proper stele.

The second leaf finally emerges and appears above ground as the first sterile
green leaf of the young sporophyte. Bruchmann states that the second leaf does not
appear above ground until five years after it is first formed, and he believes that the
sporophyte, at the time its first leaf appears above ground, is nine to ten years of age.

The third leaf may be fertile, but this is not always the case.

THE ANATOMY OF THE YOUNG SPOROPHYTE OF OPHIOGLOSSUM.

In Ophioglossum pendulum the young primary root soon breaks through the
prothallium and elongates rapidly, but owing to its brittleness it is easily broken
off, and it is impossible to state here just how far it develops before the bud is
formed upon it. The development of the second root varies a good deal. The first
root may reach a length of 3 or 4 centimeters before the second root can be seen
at all. ‘The growth of these earlier roots is in all respects similar to that of the later
ones. ‘There is a large tetrahedral apical cell whose divisions are quite regular,
and there is soon visible the axial vascular
bundle which extends for some distance
into the foot, where it ends blindly. The
vascular bundle of the second root joins
the first at the junction of the latter with
the foot (fig. 21, D).

The first tracheary tissue appears at
the point of junction, and is made up of
short, somewhat irregular, pointed tra-
cheids with reticulate thickenings. From
this point the development of the tracheary
tissue proceeds toward the apex of the roots.
The bundle is diarch, as is plainly seen in
cross-sections (fig. 27, £). The endodermis
is very clearly defined and the characteristic
radial markings are extraordinarily clear,
especially in sections treated with a double
stain of safranine and gentian violet. The
A. Longitudinal section of an older bud of Ophioglossum tracheary tissue 1s also beautifully differen-

moluccanum. X50. st, stem apex; /* first leaf of _ tiated by this stain. The bundle is slightly
SE aa aah 2 elliptical in form and the protoxylem ele-
ments appear at the foci of the elliptical
section. The first appearance of the tracheary tissue is some distance back of the
apex and the development proceeds rather slowly. In the oldest part of the roots

Fic, 26.

THE EMBRYO 45

examined the two xylem masses were unequal in size, the larger showing about
half a dozen tracheids in cross-section, the smaller two or three. Whether the two
protoxylems are ultimately joined by intermediate tracheal tissue, so as to form a
continuous plate, as in the older roots of the adult plant, can not now be stated, but
in no cases examined was this true, and it is not unlikely that in the primary root
the two xylem masses are permanently separated. The cells of the foot, as usual,
are more or less papillate where they are in contact with the tissue of the gameto-
phyte. They early become infected with the endophyte, which probably makes its
entrance from the prothallial tissue, and not from the outside. This point, however,
is not perfectly clear. The infected area follows the growth of the young root, but
leaves the apical tissues free.

In O. moluccanum the leaf is the first part of the young sporophyte to develop.
In the larger embryos the leaf forms a conical body, merging into a nearly globular
basal portion, which is the foot, and within this, probably near the junction of the
epibasal and hypobasal halves of the embryo, the apical cell of the root is developed.
The leaf now shows a definite apical cell, triangular in section and exhibiting a
regular segmentation. The inner cells of the segments form the axial strand of
tissue, which is continued through the embryo into the root. The limits of the two

Fic. 27.

. Section of petiole of cotyledon of O. moluccanum.

. Section of young root.

. Vascular bundle of median region of young sporophyte.

- Vascular bundle of primary root.

- Vascular bundle of primary root of O. pendulum; en, endodermis.

Booms

primary organs, the leaf and the root, remain quite indistinguishable. The central
region, which remains surrounded by the prothallial tissue, is somewhat larger in
diameter and the whole of this functions as a foot, although it is composed in part
of tissue belonging to the root and the leaf. The young leaf elongates rapidly after
it has ruptured the calyptra, and its apex begins to widen out, but still shows a
single apical cell. As the upper part widens out there is a division of the original
vascular cylinder, and there is developed within the leaf a reticulate system of
vascular bundles or veins (fig. 22, D, E£).

As already indicated, the vascular strand of the young sporophy te 1s continuous
through the cotyledon and root, and sections at different points show essentially the
same structure. The petiole of the cotyledon (fig. 27, 4), which is traversed by two
large lacunz, shows that the axial bundle is decidedly collateral in structure. The
xylem consists of a group of about half a dozen tracheids at the inner limit of the
bundle, and no endodermis can be recognized. As a section of the bundle is made

46 THE OPHIOGLOSSALES

in the mid-region of the sporophyte (fig. 27, C), the only difference noted is a slightly
greater development of the xylem. The section of the root (fig. 27, D) presents
almost exactly the same appearance as that of the leaf. Whether we should call the
root bundle “monarch” or “collateral” is merely a question of terms. In the mid-
region the endodermis can be clearly seen, and it is then evident that the xylem is
separated from it by a single layer of pericycle cells.

4

Fic. 28.

A. Archegonium of Botrychium virginianum, containing a two-celled embryo. 275.
B. Four longitudinal sections of an embryo with 7 cells. 275.

THE EMBRYO OF BOTRYCHIUM.

The following account of the development of the embryo of Botrychium is
based mainly upon material of B. virginianum furnished me through the kindness
of Professor Jeffrey.

In this species, as in the other Eusporangiate, there is a marked increase in the
size of the fertilized ovum before the first division takes place. At the time of the

Fic. 29.— Young embryos of Botrychium virginianum.

Longitudinal sections. 200. bb, basal wall. A. Four-celled embryo. B-D. Older stages.

first division the ovum is generally more or less elongated, but this is not always the
case. This elongation is less marked in B. lunaria (fig. 36), while in B. obliquum
the ovum becomes much elongated before the first division occurs (see Bower 9,

fig. 266).

THE EMBRYO 47

The first division wall, the basal wall, as in the other Eusporangiate, is, usually
at least, transverse to the axis of the archegonium (fig. 28, 4). Each of the cells thus
formed is next divided by a vertical wall, so that the embryo is divided into approxi-
mately equal quadrants. Jeffrey states that the quadrants are next divided by a
third (transverse) wall, so that there is a regular octant formation ( Jeffrey 1, page
16), but adds that this segmentation presents various irregularities and this is
confirmed by my own studies of the young em-
bryo. In B. lunarta, according to Bruchmann,
the octant divisions are very regular.

In B. virginianum the young embryo is
often somewhat pointed above, and transverse
divisions of such embryos may show that the
octant formation is suppressed in the epibasal
region, and this tapering upper part of the young
embryo suggests a suspensor similar to that de-
veloped in Danea, but less clearly defined, and
probably not determined by the first division of
the embryo. Whether the suspensor found by
Lyon in B. obliquum (Lyon 1) originates ina Fis. 30.— Three longitudinal sections of a young
similar fashion remains to be seen. This elonga- een eee aren ihe, bs
tion of the upper part of the embryo, whether it
is considered as a suspensor or not, is doubtless, as Jeffrey has suggested, useful
in pushing the developing embryo deeper down into the prothallial tissue.

For some time, only anticlinal walls are formed, this showing especially plainly
in transverse section (fig. 31). Sooner or later periclinal walls are also formed, and
it is possible that in some cases the first periclinal wall in one of the large epibasal
cells may establish the initial cell of the root, but this is hard to decide. The early
stages of the embryo are extremely difficult to embed without shrinkage, and this,
together with the difficulty of securing a sufficient number of the right stages and
the impossibility of regulating the direction in which they are cut, makes the deter-
mination of the origin of the primary organs of the young embryo a peculiarly

difficult problem.

Fic. 31.—Four horizontal sections of a young embryo of B. virginianum.

1 is next the archegonium; 2 and 3 are nearly median sections.

Neither Jeffrey nor Bruchmann was able to recognize a root initial until the
embryo had attained a large size, and its origin could not be determined. In the
embryo shown in fig. 30, I am inclined to believe that the cell r is really the root
initial. Unfortunately, stages between this and the one shown in fig. 32, where the
root initial is unmistakable, were wanting, but the position and state of develop-
ment of the root in the latter harmonize with this supposition. My fig. 32 is evi-
dently of about the same size as Jeffrey’s fig. 46, and probably an examination of
other sections of the series from which Jeffrey's fgure was drawn would show the
root initial, as well as traces of the stem apex and cotyledon.

48 THE OPHIOGLOSSALES

All of the organs of the young sporophyte arise, as Jeffrey showed, from the
epibasal region, and in this respect Botrychium vrrgintanum agrees with the Marat-
tiacew and with Ophroglossum. According to Bruchmann, the embryo in B. lunarta
remains quite undifferentiated up to the time it breaks through the calyptra, even
the root apex being unrecognizable at this time. It is therefore impossible to say
what relation the organs of the young sporophyte bear to the primary divisions of
the embryo.

Fig. 32.—Three sections of an older embryo of Botrychium virginianum, cut transverse to long axis of embryo.

bb, basal wall; f, foot; r, root; sf, stem apex; cot, cotyledon. 200.

In B. wirginianum traces of the quadrant formation are still evident at a com-
paratively late stage, and there seems no reason to doubt the correctness of Jeffrey’s
conclusion as to the epibasal origin of both the root and the cotyledon. As in
Ophioglossum pendulum and O. vulgatum, the root is especially conspicuous and
reaches a large size, while the stem apex and cotyledon are still inconspicuous.
Indeed, in B. lunaria, according to Bruchmann, no trace of either stem apex or
cotyledon can be made out
until the root has broken
through the calyptra. At
this stage (fig. 36, C, D)
the embryo of B. lunaria
bears a_ striking resem-
blance to that of Ophro-
glossum vulgatum.

It was found by Jef-
frey in B. virgintanum
that the stem initial was
developed before the co-
tyledon could be seen, but
I have failed to verify this
in the specimens I have
Fic. 33-—Two sections of an older embryo of Botrychium virginianum, cut in the examined. Fig. 32 shows

plane of the cotyledon. C -

three sections of a series
taken from an embryo of
about the age of Jeffrey’s fig. 46. This embryo was cut transversely to its long axis,
and the root apex is thus seen in cross-section. The root here probably comprises
the whole of one of the epibasal quadrants, from the other of which, or from part of
it, perhaps a single octant, the stem apex and cotyledon arise in close proximity. It
is probable that part of this quadrant goes to form the “suspensor,” or that epibasal
tissue which is not concerned in the formation of the young organs of the embryo.
Fig. 32, B shows a section passing through the young cotyledon, whose single apical
cell is already differentiated. This in section is triangular, and the cell is probably
of tetrahedral shape. Fig. 32, C, shows the section passing through the stem apex.

st, stem apex; r, root; f, foot. X100.

THE EMBRYO 49

Probably the large cell (st) is the apical cell, but this is not absolutely certain. In
form and position this cell resembles the apical cell figured by Jeffrey (Jeffrey 1,
fig. 48) in an older embryo. It may be said that in Jeffrey’s hgure the beginning of
the cotyledon, situated between the stem apex and the root, although not lettered, is
evidently present.

As the embryo grows the root rapidly increases in length, and together with the
foot comprises the greater part of the embryo. The foot ts very large, usually
nearly hemispherical in form, but not infrequently a good deal elongated (fg. 35),
and penetrates deep into the prothallial tissue.

The apical cell of the root is very conspicuous and can be made out without
difficulty as a large cell, triangular in form, whether it 1s viewed in longitudinal or
transverse section. Segments are cut off in regular sequence from all of the four
faces, and as these are relatively large and contain but little granular contents the
apical meristem shows very clearly against the smaller celled and more deeply stained

Fic. 34.

A-C. Three horizontal sections of an old embryo of Botrychium virginianum. 75.
D. The stem region. X150.

adjacent tissue. In the earlier stages the divisions in the segments cut off from the
apical cell do not show absolute uniformity. The first wall in the young segment ts
probably anticlinal, and seems to be followed by a periclinal wall or walls, cutting
off inner cells which contribute to the very large plerome cylinder of the young root.
The root cap, which is very massive, is derived in part from segments cut off directly
from the apical cell, and in part from cells separated by periclinal walls from the
outer part of the lateral segments of the apical cell.

The development of the plerome begins very early, and it soon forms a con-
spicuous massive strand of procambium cells extending from the root apex to the
junction of the root and foot, where it ends abruptly on the lower side, but bends
upward onthe upper side, and is extended as a simple axial strand of tissue into the
cotyledon.

The cotyledon, which is first recognizable at an early stage in the development
of the embryo, at the stage in question (fig. 35, 4) projects slightly as a broad, flat-
tened cone, strongly bent away from the root. Fig. 34, 4, shows the cotyledon cut

4

50 THE OPHIOGLOSSALES

through horizontally. At the slightly projecting apex there is a single apical cell,
although it is not always quite certain which is the apical cell and which is its
youngest segment. The broad base of the cotyledon is extended laterally, like the
stipules of the older leaves, and there is thus inclosed a slightly depressed area, very
much as in the embryo of Ophroglossum vulgatum, and within this is situated the
stem apex, close to the base of the cotyledon, which bends over it so as to leave
only a narrow space above the stem apex. A section across the base of the cotyledon
shows a group of small cells indicating the section of the young vascular bundle
which lower down (fig. 34, C) joins the young bundle of the primary root.

The relative position of the young organs just before the root ruptures the
calyptra is best seen in a longitudinal section. Such a section (fig. 35, 4) shows the
very large foot, occupying approximately half of the embryo, and deeply embedded
in the prothallium. Above this is the root, occupying the major part of the epibasal
region of the embryo and varying somewhat in position, perhaps due to the early
divisions in the young embryo. It may lie in a plane almost coincident with the
cotyledon, or it may make a marked angle with the latter. In the former case the

Fic. 35.

A. Median section of a young sporophyte of Botrychium virginianum about toemerge. X about so.
B. An older stage; 1*, second leaf; r*, second root. X20.

young vascular cylinder is continued almost straight into the cotyledon; in the
latter it bends sharply upward to meet it.

The stem apex, which is usually more or less oblique, is small and incon-
spicuous, but usually a single initial cell may be made out without difficulty, although
sometimes it is not easy to distinguish this from the younger segments which have
been cut off from it, as the apical meristem is very shallow, and in longitudinal
section has the appearance of a columnar epithelium. There seems to be, at least
in the earlier stages of development, some variation in the form of the initial cell,
which may have a pointed base, or may be truncate below, and while later it
usually shows the form of a three-sided pyramid, in these earlier stages it often
approximates the truncate form found in Ophioglossum moluccanum.

The apical meristem of the stem is very limited in extent and, so far as could
be made out, the segmentation at first does not follow any regular scheme. While
in both root and cotyledon a central strand of procambium is developed at a very
early period, no trace of anything which can be interpreted as a “stele” is formed in
the young stem. ‘The tissues derived from the further segmentation of the apical
meristem remain undifferentiated parenchyma and contribute only to the central
pith of the hollow woody cylinder which later traverses the axis of the young

THE EMBRYO Ail

sporophyte. In short, the strand of vascular tissue in the young sporophyte at the
time the first root emerges is composed solely of the coalescent strands of the root
and leaf exactly as is the case in the young sporophyte of Ophioglossum moluccanum,
and there is absolutely no trace of a cauline stele.

The foot is composed of large parenchyma cells, which become smaller
toward the periphery, where they usually show more or less dense contents and some-
times form a quite definite layer of epithelium-like cells, which stain much more deeply
than the inner tissue of the foot. This outer layer of cells is presumably active in
the absorption of nutriment from the adjacent prothallial tissue. Bruchmann states
that previous to the emergence of the root of the young sporophyte of B. lunaria
the cells of the embryo are densely packed with granular matter of apparently
albuminous nature; but after the emergence of the root starch is developed abun-
dantly in the cells of the foot. This appears to be true also of B. virginianum.

Compared with B. virginianum, the embryo of B. lunaria (fig. 36) is character-
ized by the lesser development of the foot and the later appearance and rudimentary
character of the stem apex and the cotyledon.

The stem apex in B. /unaria (Bruchmann 2) is first evident as a slight superh-
cial depression near the base of the massive root. A single superficial cell becomes
differentiated as the apical cell of the shoot, and a small group of cells is formed
before the rudimentary cotyledon develops. Both stem apex and cotyledon remain
very inconspicuous. ‘The cotyledon is developed as a scale-like rudiment, which
never develops into a foliage leaf. Bruchmann states (Bruchmann 2, page 223)
that from seven to nine of these rudimentary leaves are developed before the first
green leaf appears above the earth. Hofmeister (Hofmeister 1) believed that three
of these rudimentary leaves were developed during the first year, and that the
second year the first spore-bearing leaf appeared above ground. Bruchmann thinks
that this is not the case and that the first spore-bearing leaf requires five years for its
development, as it does in the older sporophytes, and that only one leaf is formed
each year, as in the older plant.

The first organ to penetrate the calyptra is, as we have seen, the root, which in
B. virginianum is very large and quite overshadows the relatively inconspicuous
bud at its base (fig. 7, B). "At the time the root first emerges the vascular bundles
still have the form of procambium, and it is not until the young root has a length of
several millimeters (5 to 20 millimeters, according to Jeffrey) that the first tracheary
tissue is developed. The first tracheary tissue arises at the base of the root and the
development, as usual, proceeds toward the apex. The primary root in Botrychium
virginianum is usually diarch, but triarch roots are sometimes found, and Jeffrey
says that the size of the root has no relation to the number of protoxylems formed.
The first tracheids are short and reticulately marked, as they are in Ophioglossum.
The surface of the root is quite destitute of root hairs, as is the case in the adult
sporophyte.

In B. lunarta the predominance of the root over the shoot is even more marked
than in B. virginianum, for there are several roots, sometimes four to five, developed
before the first foliage leaf is formed, and the bud remains extremely small and
inconspicuous.

A longitudinal section of the cotyledon of B. virginianum, just before it breaks
through the overlying calyptra, shows it to be strongly curved away from the root
and overhanging the cleft within which lies the stem apex. If the section is exactly
a median one, there may be seen near the tip, but lying somewhat toward the lower
side, a marginal cell of triangular outline, which, from the arrangement of the cells
about it, is evidently the apical cell. The cotyledon, instead of being straight as it

52 THE OPHIOGLOSSALES

is in Ophioglossum and Botrychium lunarta, approaches the circinate form of that of
the Marattiacew and the typical ferns. The young vascular bundle is now clearly
evident, lying somewhat toward the inner side of the leaf, and it can be readily
followed downward until it joins the root bundle, with which it is continuous.

In B. virginranum, while the cotyledon is still quite small, the second leaf
appears close to the stem apex and nearly opposite the cotyledon, the sheathing
base of which surrounds the stem apex, together with the young second leaf. The
growth of the second leaf is also probably from a tetrahedral apical cell, and this
is the case with all of the later leaves. While the second leaf is still very small,
there begins the differentiation of the corresponding leaf trace, which joins the
bundle of the primary root close to the point at which it gives off another bundle
destined for the second root, the apical cell of which is cut out from the tissue near
the base of the second leaf, at a point almost directly opposite the cotyledon.
Indeed, the second root may be said to bear much the same relation to the second

leaf that the primary root does to the cotyledon (fig. 35, B).

saneNe

Fic. 36.—Botrychium lunaria (after Bruchmann).

A, B. Young embryos. X225.
C, D. Older embryos. The cotyledon and stem apex, st, are developed much later than in B. virginianum.

The cotyledon in B. virginianum (fig. 7) is extraordinarily developed, reaching
a size that probably is unequaled by any other fern. Its slender petiole reaches
a length of 5 to 6 centimeters, and the lamina, unlike the simple oval primary leaf of
Ophioglossum, is ternately divided and the segments deeply cut. The venation,
instead of being reticulate as in Ophioglossum, is apparently pinnate, but this is
really the result of an unequal dichotomy, as it is in the ultimate branches of the
veins in most ferns.

The base of the petiole forms a stipular sheath like that found in the later
leaves, and it is traversed by two vascular bundles, which unite into a single trace
before joining the bundle of the root.

While in B. lunaria all of the early leaves remain rudimentary, and the first
one to appear above ground is a fertile one, there are sometimes intermediate stages
which may show a small ternate lamina and traces of the fertile spike, although they
never appear above ground (see Bruchmann 2, fig. 50).

If horizontal sections of the young sporophyte are examined, at about the time
the cotyledon first emerges (fig. 41), the latter will be seen to have the form of a

THE EMBRYO 53

crescent, the horns of which unite at about the level of the stem apex, so that the
latter, together with the section of the second leaf, is completely inclosed by the
sheath formed at the base of the cotyledon. The leaf trace in both the cotyledon
and the second leaf is broadly oval in outline, increasing in breadth lower down,
so that the section there becomes crescent-shaped and the two together form an
imperfectly closed ring of small cells, the procambium of the future vascular cyl-
inder of the axis, which clearly is formed entirely from the united leaf traces.

The apical cell of the stem appears triangular in cross-section, and from it are
cut off regular segments, but, as we have seen from the study of the longitudinal
section, the tissues which are developed from these segments below the apical cell
remain undifferentiated and form merely a mass of large parenchyma cells with
thin walls, which fill the space within the ring formed by the confluent leaf traces,
and thus constitute the pith or medulla of the stem.

Jeffrey (Jeffrey 1, page 19) refers to the occurrence of short tracheids in the
prothallial tissue in one case which came under his observation. ‘There was some
evidence that an embryo had been present, but it had disappeared, and he thought
it possible that this was a case of apogamy, similar to that which has been repeatedly
observed in Pterts cretica and in various other leptosporangiate ferns. If apogamy
does really exist in B. virginianum it is the only case which is known among the
Eusporangiate

Botrychium obliquum (Lyon 1) differs strikingly in the form of the embryo
from either B. virginianum or B. lunarta, and these differences are so marked that
Lyon proposes to separate B. obliquum and a number of allied species as a new
genus, Sceptridium. The ovum in Botrychium obliquum becomes very much
elongated after fertilization, and it is probable that the first wall separates the part
next the archegonium from the inner cell, the former developing into a suspensor,
very much as we shall see that it does in Danea, and this suspensor becomes well
developed and is conspicuous in the later stages of the embryo. Unfortunately,
Lyon gives no details of the further history of the embryo until the definitive organs
are far advanced. He states that the suspensor becomes elongated, pushing down
the rest of the embryo, which he calls the “ protocorm,” believing that it is homol-
ogous with the so-called “protocorm” of Lycopodium—a resemblance which would
probably disappear were a more thorough study of the subsequent history available.
This development of a suspensor is the first case described in the ferns, but, as we
shall see presently, a similar suspensor is regularly present in the genus Danea,
which in other respects shows some interesting resemblances to B. obliquum in the
development of the embryo. Moreover, as we have seen, there is often an elonga-
tion of the upper cells of the young embryo of B. virginianum, which suggests a
rudimentary suspensor.

Lyon figures only a very advanced stage of the embryo, at about the time when
the root first emerges from the prothallium. At this time, aside from the presence
of the suspensor, the most marked difference between B. obliquum and B. virgin-
ianum is the apparent absence of the foot in the former species, while this organ is
so remarkably developed in B.virginianum. ‘The root in B. obliquum penetrates the
lower surface of the gametophyte, the cotyledon breaking through on the upper
side, so that the relative position of the leaf and root is like that of Ophioglossum
moluccanum, or the Marattiacee. In the orientation of the root and shoot, there-
fore, B. obliquum is much more like Danea or Ophioglossum moluccanum than it
is like B. virgintanum.

It is to be hoped that further investigations will be made upon this extremely
interesting species. We anticipate that when the history of the earlier stages 1s

54 THE OPHIOGLOSSALES

known it will be found that a large foot is present in the embryo, as it is in the
Marattiacee and the other Ophioglossacez, and the apparent absence of this foot
in the older embryo is due to the root apex being formed deep in the central tissue
of the embryo, as it is in the Marattiacee and in Ophioglossum moluccanum, and
pushing its way downward through the foot, which thus becomes indistinguishable
from the outer tissue of the root.

Except for the absence of the foot the organs of the older embryo of B. obliquum
show the same relative positions as those of B. virginianum, and, as in the latter,
the first leaf is apparently a functional green leaf which appears above the surface
of the earth.

THE EMBRYO OF HELMINTHOSTACHYS.

The embryogeny of Helminthostachys, the third genus of the Ophioglossacezx,
is unfortunately very incompletely known. L ang (Lang 1), to whom we owe the
only published account of the gametophyte and young sporophyte, was unable to
secure any young embryos and only very scanty material of the later stages. Lang
says of the youngest forms which he found (Lang 1, page 40):

“The large hemispherical foot is deeply inserted in the tissue of the prothallium.
The upper portion of the embryo had burst through the covering also of the latter,
in it can be distinguished the primary root—the first leaf—and (covered over by
the sheath of the first leaf) the depressed apex of the stem. ‘The position of the
organs is thus essentially similar to what is found in Botrychium virgintanum.”

Lang’s material was collected in the Barrawa Reserve Forest, in Ceylon, and
in February 1g06 I visited the same locality and collected a large number of young
sporophytes, many of which were still connected with the gametophyte; but none
of the gametophytes were young enough to show young embryos. As we have
already suggested, it seems very probable that the gametophyte of Helminth-
ostachys, like that of Ophtoglossum moluccanum, is annual and produces normally a
single sporophyte, after which it perishes. “The development of the gametophyte is
probably dependent upon the annual inundation of the forest, and this perhaps
accounts for the fact that all of the young sporophy tes were of about the same age.

The youngest specimen which I found is shown in fig. 10. The petiole of the
leaf was about 1 centimeter in length, and at the tip the minute lamina, strongly
bent over like the young leaves of Botrychium virginianum, could be seen, showing
the three lobes which characterize the fully expanded leaf. The cotyledon is rudi-
mentary in Helminthostachys, the “cotyledon” described by Lang being really the
second leaf. At the base, but separated from the root by a short internode, is
a swelling which marks the position of the apical bud, inclosed within the hollow
sheath at the base of the petiole. The root at this stage is still quite short, the first
green leaf seeming to be more precocious than in Botrychium and thus resembling
Ophioglossum moluccanum.

As the leaf grows the lamina expands and is seen to be ternate in form. Very
often the two lateral lobes are of unequal size and show that the ternate form is due
to an unequal dichotomy, such as is common in many ferns in the early leaves, which
are transitional between the dichotomously divided cotyledon and the pinnate
leaves of the older sporophyte. The ultimate divisions of the veins, as in Botrych-
tum, are dichotomous.*

* In a recent note (Lang 2) it is stated that a suspensor also occurs in Helminthostachys.

THE YOUNG SPOROPHYTE 55

It THE YOUNG:SPOROPHY TE.
THE YOUNG SPOROPHYTE OF OPHIOGLOSSUM.

As we have seen, the single vascular strand in the young sporophyte of Ophio-
glossum moluccanum is continuous through the cotyledon and root, and sections
at different heights show essentially the same structure throughout. ‘The petiole
of the cotyledon (figure 27, 4), which is traversed by two conspicuous lacune,
shows that the axial bundle has a perfect collateral structure. The xylem consists
of a group of about a half dozen tracheids on the inner side of the bundle, of which
the endodermis, however, is not evident. If a section made in the mid-region of
the plant is examined, the only difference between its bundle and that within the
petiole of the leaf consists in the somewhat greater development of the tracheary
tissue. The section of the root bundle also almost exactly resembles that of the leaf.
Whether we call the root bundle monarch or collateral is merely a question of terms.

Fic. 37-

A-C. Three sections of a young sporophyte of O phioglossum moluccanum with the first leaf, /*, of bud fully
developed; r, primary root of sporophyte; r’, first root of bud; /*, second leaf of bud.
D. The stem-apex more highly magnified, showing the third leaf, /°.

In the mid-region of the sporophyte the endodermis is well marked, and this is even
more the case in the root. In the mid region the xylem is separated from the endo-
dermis by a single layer of pericycle cells.

About the time that the leaf emerges the first root of the bud begins to develop,
and, like the leaf, it seems to arise quite independently of the stem apex. The
tetrahedral apical cell is cut out from the. cortical tissue of the root some distance
below the apex of the young bud, and as soon as the apical cell is established active
segmentation begins in the tissue below the bud and a strand of procambium is
developed, connecting the young root apex directly with the vascular bundle of the
primary root. Thus the vascular bundles of both the first leaf and the first root of
the young bud are directly connected with the primary root of the young sporo-
phyte and have nothing to do with the tissues in the apex of the stem of the bud,
which is still very small.

56 THE OPHIOGLOSSALES

The two bundles, belonging respectively to the leaf and the root of the bud,
join the bundle of the primary root very near together, and from near this point of
junction the development of the tracheary tissue proceeds toward the apices of the
young organs. The first tracheids, like those found in the median region of the
young sporophyte, are short reticulate ones.

‘The first leaf of the bud grows rapidly and closely resembles the cotyledon in
form and size, and at first it often looks as if two young sporophytes of equal size
were growing from the prothallium, but a very slight examination shows that the
second leaf belongs to the bud upon the primary root. The second leaf of the bud
also seems to be formed independently of the stem apex and arises nearly opposite
the first one (fig. 37, 4). Its development is practically the same as that of the
first leaf, and it pushes through the outer tissue of the root at a point removed by an
appreciable distance from the base of the first leaf, from which it is separated by a
sheath about the base of the latter, formed by the outer root tissues.

The vascular bundle in the second leaf is soon developed and can be followed
down to the bundle of the first root of the bud, to which it bears somewhat the same
relation that the bundle of the first leaf of the bud does to the primary root of the
sporophyte. Fig. 37 will show clearly the arrangement of the vascular bundles in
a young bud in which the first leaf is fully developed, while the second and third are
pretty well advanced. ‘The latter (/°) shows very plainly the conspicuous apical
cell and the beginning of the leaf trace. The apical cell of the stem at this time is
sufficiently conspicuous, but the amount of tissue surrounding it is quite limited
in extent. In fig. 37, D, it is probable that the fourth leaf has begun to develop.
Above the apex of the stem the cavity of the leaf sheath can be clearly seen. By
this time the first root of the bud has emerged below the first leaf and the tracheary
tissue is well developed in its basal region.

The second root of the bud originates below the apex of the stem in the vicinity
of the base of the second leaf. The vascular strand of the third leaf joins it, and the
third leaf seems to have somewhat the same relation to the second root that the
second leaf does to the primary root.

The study of the development of the young bud shows that, up to the time of the
production of the third leaf, the young organs arise quite independently of each
other from the tissue of the primary root. The young sporophyte is, so to speak,
made up by the union of several independent members. The third and fourth
leaves arise from the stem apex as all of the later ones do, but the first and second
leaves and the first root show no recognizable relation to the stem apex. Their
vascular bundles are directly connected with the bundle of the primary root of the
young sporophyte, and are in no way associated with the tissues which belong to
the stem region of the bud. No material was available for the study of the origin
of the leafy bud in O. pendulum, but the first leaf evidently develops very much
later than it does in O. moluccanum. Young leaves 10 centimeters or more in length
were found, which, there is some reason to suppose, were the primary leaves of the
young plant; but they were not recognized as such at the time they were collected
and it is therefore impossible to say whether they really were the first leaves devel-
oped. After the study had been made of the young sporophyte in O. moluccanum,
and the secondary origin of the stem apex was made out, it was recognized that these
small leaves in O. pendulum also were probably the primary leaves of the plant, but
it was too late then to trace the connection of the roots from which they developed
to their connection with the primary root of the young sporophyte.

I was unable to determine just how soon the fertile leaves are developed from
the young sporophyte in O, moluccanum. In all of the specimens that were sectioned,

THE YOUNG SPOROPHYTE 57

the first three or four leaves were sterile and practically like the cotyledon, and it
is not certain which leaf, under ordinary circumstances, first gives rise to the spore-
bearing spike. In O. moluccanum and the other tropical species of Ophioglossum
growth is continuous, and it is evident that the development of the leaves does not
take the long period required in O. vulgatum and other species of temperate regions,
where growth is interrupted each year and where only one leaf is developed in the

Fic. 38.

Six of a series of transverse sections of a young sporophyte of Ophioglossum moluccanum, still attached to primary
root,r. Section B passes through the stem apex. X35.

season. Mettenius states that O. pedunculosum, which, as we have seen, may per-
haps be identical with O. moluccanum, develops three leaves each season. This
was in the Botanical Garden at Leipzig, and it is highly probable, under the
much more favorable conditions of its native tropical habitat, that this number
would be exceeded. There was not time to make investigations in regard to this
: point, but it is very certain
that several leaves are de-
veloped in the course of each
year and that the develop-
ment of the individual leaf
does not require the long pe-
riod necessary in the species
of cold climates.

Figures 38 and 39 show
several transverse sections
forming a series taken from
a young sporophyte with
three fully developed leaves
and two younger ones. This
bud was developed from a
small root, but it was not
certain that this was the
primary root of the embryo.
A. Section of the sporophyte shown in fig. 38, showing arrangement of leaves; lhe spirally a rranged leaves

ris the primary root. X about 60. show the two-fifths diver-

B. Vascular bundle of first leaf, more highly magnified. : Tp =
C. Stem apex, showing youngest leaf trace, 1°; st, apical cell of stem. OME: he second and
third leaves of this bud

were successively larger than the first leaf, but the section of the petiole showed
a single centrally placed vascular bundle of the same type as that of the primary

Fic. 39.

8 THE OPHIOGLOSSALES

nn

leaf and all of these leaves were sterile, nor could any indication of the develop-
ment of a central spike be seen in the development of the fourth leaf. The first
leaf of the bud, like the cotyledon, showed two large lacunz in the petiole, but in
the second leaf there was but a single one and this was interrupted at intervals,
while the petiole of the third leaf appeared almost solid, there being only small,
irregular, intercellular spaces, such as are always found in any loose parenchyma.
All of the vascular bundles are collateral. In the lower portion of the third leaf
eleven tracheids could be seen in the transverse section of the bundle, but higher
up the amount of tracheary tissue was reduced.

Figs. 38, 4, and 39, 4, were cut just above the stem apex and showed clearly
the arrangement of the first four leaves. The youngest leaf is still entirely surrounded
by the conical stipular sheath belonging to the third leaf. Fig. 38, 4,1s taken imme-
diately above the stem apex and passes through the very young fifth leaf. This
section shows very satisfactorily the arrangement of the first five leaves. Section C
lies a short distance below the stem apex. r is the root from which the bud has
arisen, and the group of tracheids at its junction with the bud marks the point
of union of the bundles of the first leaf and the first root of the bud. In the center
of the section may be seen a mass of large-celled parenchyma, the central pith of the
stem, which is derived from the large-celled meristem of the stem apex. ‘The broken
ring of procambium surrounding the pith is composed of obliquely cut traces of the
fourth and fifth leaves and the basal tissue of the second root of the bud. The leaf
traces from the second and third leaves are still free in the cortical tissue of the young
stem. £ and F pass through the base of the bud. The stout bundle of the first
root is seen connected with the bundle of the root upon which the bud was developed,
and the second leaf trace (/*) bends in to meet the bundle of the root but is cut
at a level above the point of junction. Close to the second leaf trace is the lower
part of the fourth leaf trace, which is connected with the trace of the second root
of the bud. The steles of both the first and second roots of the bud run horizon-
tally across its base before they emerge, and the leaf traces are almost perpendic-
ular to these. The second leaf trace at the base of the bud joins the stele of the
first root and the short tracheids curve out trom the opposite side of the bundle of
the first root to unite with the base of the third leaf trace, which does not, as might
have been expected, show any very obvious relation to the second root. At the
point where the first root bends downward to emerge from the overlying cortical
tissue the tracheary tissue of this, with the bases of the leat traces, forms a large
mass of irregular, broad, reticulate tracheids, occupying the center of the base of
the young bud. It was probably the presence of this mass or tracheary tissue at the
base of the bud which led Rostowzew to state that the bundle of the bud is at first
solid. It is possible that the buds formed on the old roots ot O. vulgatum may be
somewhat different in structure from the early buds in O. moluccanum and that
there really may be such a solid stele at its base.

According to Rostowzew (Rostowzew 1, 2) and Poirault (Poirault 2), the buds
upon the older roots of O. vulgatum usually arise close to the apex, much as they
sometimes do in the formation of the bud upon the primary root of O. moluccanum.
Van Tieghem thought that the apex of the root itself became changed into the
leafy shoot, but both Poirault and Rostowzew demonstrated that the young bud
originated from a segment of the apical cell of the root and not from the apical
cell itself; the latter continues its growth and the root thus grows beyond the
point of insertion of the young bud. Rostowzew states that an outer cell of the
segment divides into two superimposed layers, of which the superior one, or the
one nearest the root apex, gives rise to the stem apex of the bud, while from the lower

THE YOUNG SPOROPHYTE 59

one, i. e., the one turned toward the base of the root, the first leaf arises. It thus
appears flat in these adventitious buds in Ophioglossum vulgatum there is much
the same arrangement of the first organs of the young bud that we have seen to be
the case in O. moluccanum, the leaf and the stem apex being virtually independent
organs. From Rostowzew’s figures it is evident that the bundle from the first leaf
of the bud in O. vulgatum is connected directly with the main root tn very much
the same way as it 1s in the primary bud in O. moluccanum; but apparently the first
root of the young bud is inserted higher up and does not connect directly with the
primary root; this point, however, needs further elucidation. Moreover, according
to his statements, there is a good deal of difference shown as to the time of the emer-
gence of the leaves and roots, three or four roots sometimes being well developed
before the first leaf expands. This reminds one of the behavior of the primary
sporophyte, where Bruchmann found that several roots were developed before the
first green leaf made its appearance.

D

Fic. 40.—Vertical sections of a young sporophyte of Botrychtum virginianum. The sections were cut at
right angles to the axis of the root. sh, stipular sheath of cotyledon; E, section of primary root,
which in this case was triarch. X20.

THE YOUNG SPOROPHYTE OF BOTRYCHIUM.

Jeffrey (Jeffrey 1) has described at some length the structure of the young
sporophyte of B. virgintanum, and Bruchmann (Bruchmann 2) has studied the
earlier stages of the sporophyte 1 in B. lunaria. The present account is based mainly
upon my own studies of B. virgintanum, made from material furnished me through
the kindness of Professor Jeffrey. “Jeffrey found that from the beginning the con-
spicuous stele found in the axis of the young sporophyte was a hollow cylinder,
which he assumes to be a really cauline structure, and not made up of leaf traces.
The results of my own studies indicate that, as in the case of Ophioglossum, the
vascular system of the stem is made up exclusively of confluent leaf traces

Fig. 35, B, shows a longitudinal section of a young sporophyte 1 in which the first
two leaves are evident and the continuation into these of the tissues of the vascular
bundle of the root is very clear. The large central pith continues up into the stem
apex, but the whole of the fibrovascular tissue is continued into the leaves, there

60 THE OPHIOGLOSSALES

being no trace of procambium inside of the leaf traces in the apical region of the
stem itself. Fig. 40 shows a sporophyte which was cut at right angles to the primary
root, which in this case had a triarch bundle. Near its base the three xylem masses
increase in size and form a nearly complete ring of tracheary tissue, which higher
up is continued into the leaf traces. The third leaf has already begun to form, but
is still very small. Below it, however, can be clearly seen the beginning of its large
leaf trace, which can be followed downward to its junction with the second root,
which is now just about ready to emerge. ‘The stele of the second root is con-
nected with the central cylinder of the axis near its junction with this third leaf
trace. The stem apex occupies a very small area, crowded between the base of the
second and third leaves. Its deep, narrow, apical cell is not as conspicuous as is
often the case.

LG

Fic. 41.

A-F. Six of a series of horizontal sections of a young sporophyte of Botrychium virginianum. X75.
B passes through stem apex, st, which is shown more enlarged in G; r*, second root; /*, second leaf.

A similar sporophyte is shown in cross-section in fig. 41. This was cut in
the plane of the first root, which makes a sharp angle with the base of the cotyledon.
The thick stele of the root is much expanded where it joins the leaf traces to form
the beginning of the tubular stele of the axis, and at the point of junction there is
a large nearly solid mass of short, irregularly disposed, reticulate tracheids. ‘This
young sporophyte was evidently the further development of an embryo of the
type shown in fg. 35, 4. The trace of the cotyledon makes a right angle with the
stele of the root and on the side opposite to its junction with the stele of the root
there can be seen the trace belonging to the second leaf, which is already well
developed. The apical cell is tetrahedral in Botrychium virginianum and the
cells are cut off in regular segments from its three lateral faces. Segmentation is

THE YOUNG SPOROPHYTE 61

evidently slow and there is usually a good deal of difference in the stage of develop-
ment in the three segments composing a single cycle. The first division in each
of the lateral segments cuts off a small inner cell from a large outer one, and the
latter is then divided into two by an anticlinal wall. The divisions were not followed
beyond this stage and the limits of the segments comprising the second cycle can
not be easily recognized, as by this time the youngest leaf begins to grow ‘and the
stem apex is thus crowded into a very small area between the bases of the two
youngest leaves. The shallow mass of meristematic tissue comprising the stem apex
merges gradually into the large-celled parenchyma which makes up the pith cylinder
inside the hollow stele of the axis.

Longitudinal sections of a much older sporophyte are shown in fig. 42.

Except for the vascular bundles, the whole of the tissue of the y oung sporophyte
is composed of large-celled parenchyma which, especially in the region belonging
to the foot, contains large quantities of starch.

The form of the young leaves in B. virginianum is very different from that
in B. lunarta. Inthe fonaer the young leaf is ‘bent forward over the stem apex and
the apical cell is at the tip of this hee -over portion. In B. /unaria, however, the

Fic. 42.

Three longitudinal sections of a young sporophyte of Botrychtum virginianum, with several leaves.
per, absciss layer of periderm; /,/, the youngest leaves; sh, stipular sheath. X20.

bent-over portion becomes the stipular region and the apical cell of the young leaf
arises in the convex upper portion, so that the leaf grows straight upward instead
of being bent over as it is in B. virgintanum. ‘The latter species in this respect
pesoaibies the Marattiacee.

The stipules in B. virginianum are lateral structures which extend around the
next youngest leaf and the stem apex, but the sheath has a narrow cleft in front, so
that we may really speak of two stipules instead of a single stipular sheath (hg.
42, 4). In this respect also there is a strong resemblance to the Marattiacez.

Fig. 43 shows a series of transverse sections of a young sporophyte of B. vrr-
ginianum i in which the fourth leaf was just evident. Fig. 43, 4 and B, are near
the base of the fourth leaf and show the arrangement of the first four leaves. The
base of the cotyledon (cot) is a good deal flattened and the petiole is seen to be
traversed by very conspicuous lacuna, reminding one of those in the cotyledon of
Ophioglossum moluccanum. The conspicuous “stipules can be seen extending
partly around the group of younger leaves, but not completely inclosing them. The
two vascular bundles of the petiole are beginning to unite to form the single leaf
trace which is found lower down. The xylem in, each bundle forms a broad band

62 THE OPHIOGLOSSALES

of wood, which is surrounded by the phloem, although the latter is much less
developed upon the inner side than upon the outer and the bundles thus approach
the collateral condition found in the trace lower down. Small protophloem ele-
ments occur in the outer part of the bundle and are continued part way around
toward the lower side, to the point where the two bundles are beginning to fuse,
but here they are no longer visible. ’

The second leaf shows no lacunae and the base of the petiole is more nearly
cylindrical than is that of the cotyledon. Like the latter, the petiole contains two
vascular bundles which at the level of this section were still quite distinct, and the
permanent elements were just beginning to form. ‘The stipules in the second leaf
completely inclose the third, but there is a very narrow slit in front where the two
stipules meet. ‘The next section figured is taken just above the stem apex and cuts
through the youngest (fourth) leaf. The two bundles of the petiole of the third leaf
are evidently still quite separate, but closely approximated, and as yet show no per-
manent tissue. The stipules of the third leaf are just becoming evident. At the
level of the stem apex the bases of the third and fourth leaves are completely united,

Fic. 43-

Series of transverse sections of a young sporophyte of Botrychium virginianum, showing union of leaf traces to form vascular
cylinder. D and E show the separated leaf traces which unite further down; K shows the bundle of the axis near
its junction with the stele of the primary root.

and the base of the second leaf is also partially fused with these. ‘The two bundles
from the second leaf are now beginning to unite to form the single leaf trace, while
in the third leaf the process is complete and a single oval mass of procambium cells
marks the position of the single trace of this leaf. On the opposite side of the
apical meristem is a similar but less developed mass of procambium, representing
the trace from the young fourth leaf.

For some distance below the stem apex the two bundles of the third and fourth
leaf respectively are quite distinct, and are separated from each other by a mass of
large-celled pith. Lower down the two bundles approach and coalesce, and on the
side of the second leaf trace (which is turned away from the third one) a group of
actively dividing cells can be seen which forms the beginning of the fifth leaf trace,
although the leaf itself can not be recognized at the summit. These three masses
of procambial tissue, viz, the young traces from the third, fourth, and fifth leaves,

THE YOUNG SPOROPHYTE 63

make a nearly continuous crescent-shaped mass of procambium. Fig. 44, 4, B, shows
the section of the central stele; and the space between the horns of the crescent, 1. e.,
the space between the third and fifth leaf traces, constitutes the so-called ‘foliar
gap” which faces the second leaf trace. The central cells of the young stele have
already begun to form cambium, which in the older stem constitutes such a char-
acteristic feature of the stele.

Before any tracheary tissue is formed in the young stele, a few thick-walled
cells can be seen in the outer part of the portion of the stele corresponding to the
third leaf trace. These are protophloem cells, and similar ones are developed later
in the younger parts of the stele. The first tracheary tissue appears in the region
of the steel section belonging to the third leaf trace. In the section shown (fg. 44, C)

Fic. 44.

A, B, C. The young vascular bundles of sections E, F, G, of the series shown in fig. 43. 150.
D. Section of a young sporophyte of Botrychium virgintanum, showing junction of a leaf trace with
stele of axis. X75.

there are three groups of these primary tracheids, separated by a considerable interval
and placed at the extreme inner limit of the young stele. In the older portions of
the bundle the number of these increases and similar ones make their appearance
in the next younger section of the stele, that belonging to the fourth leaf. Last of
all, these primary tracheids are formed in the younger region of the stele and new
ones arise between these first-formed ones, so that there is developed a nearly
complete circle of tracheids marking the inner boundary of the tubular stele.

The second leaf trace approaches nearer and nearer the two horns of the
crescentic stele section as it is followed downward, and finally joins it, filling up
the gap between the regions belonging to the third and fifth leaf traces. Thus, for a

64 THE OPHIOGLOSSALES

time the section of the stele appears perfectly circular and continues downward
until it reaches the next leaf trace, which marks the point of departure of the
trace of the cotyledon, Except for the greater development of the xylem, which is
composed of two to three concentric rows of tracheids, the section of the stele in this
region presents much the same appearance that it does in the younger parts nearer
the stem apex. The outer part of the stele at this point shows a somewhat broken
row of thick-walled bast fbers within which are large sieve tubes. The cambium,
lying just inside the phloem, is very much less developed in the basal region of the
stele than it is higher up and can scarcely be said to be present. The stele in this
region of the stem is quite similar to that of B. /unarta, figured by Poirault. The
endodermis is also much less definite than it is later, and I could not satisfy myself
that there was in B. virginianum any trace of the inner endodermis which Poirault
states is present in the basal part of the stem in B. /unaria, but which disappears
later. The medullary rays also, which are conspicuous in the stele of the older
plant, are very imperfectly developed in this basal region.

In the intermediate region, between the base of the primary root and the trace
from the cotyledon, a section shows a thick irregular ring of tracheary tissue with

no clearly developed medullary rays (fig. 43, L). Indeed, at the lowest part of this
region the tracheary tissue forms an almost solid core with only a small amount of
parenchyma interspersed, thus forming an inconspicuous and irregular pith. While
the endodermis is not clearly delimited, some of the cells in the zone of tissue sur-
rounding the stele show the radial thickenings of the walls; but these cells are not
all of them in the layer immediately adjoining the stele, being irregularly disposed
throughout the three or four layers of cells surrounding the stele. As sections are
examined in succession upwards, the pith becomes better defined. Sections taken
downward show a ring of tracheary tissue gradually separating into the two or three
xylem masses of the primary root.

The primary root in the sporophyte which has just been described was diarch.
The stele shows a very evident endodermis, within which is the pericycle, for the
most part composed of two layers of cells. The xylems are composed of a large
group of tracheids, of which the two or three smaller ones next the pericycle repre-
sent the protoxylems. Small, deeply staining protophloem elements can be seen
toward the outside of the phloem, and within these are the other phloem elements,
thick-walled bast fibers, and sieve tubes. The rest of the stele is composed of small,
thin-walled parenchyma cells. The outer region of the root is made up of somewhat
compressed cells suggesting the periderm cells which are found in parts of the older
stem and which are also present in the cortex of the later roots. This outer layer of
cells, however, shows no evidence of active division.

A cross-section of the petiole of the cotyledon, from the same sporophyte, taken
at a point some distance above the stipules, shows within the epidermis about three
layers of parenchyma cells with no conspicuous intercellular spaces, but within
these are several very large lacuna, separated by narrow plates of tissue. In the
center of the section are seen the two concentric bundles that traverse the petiole.
As in the later leaves of this species, these bundles are truly concentric, thus resem-
bling those of the Marattiacez and differing from the collateral bundles of Ophro-
glossum and the smaller species of Botrychium. \The phloem is better developed
upon the outer side and small protophloem elements can be seen at its outer limit,
but these are continued partially around the inner side of the bundle, where the
xylem is separated from the outside by about two layers of cells. No definite
endodermis can be made out. The two bundles are continued up to the base of the
lamina, where one of them passes into each lateral lobe of the ternate leaf. One of

THE YOUNG SPOROPHYTE 65

these divides and gives off a branch which passes into the terminal lobe of the leaf
(see Jeffrey 1, page 23).

In a section of the older stem, about where the fourth leaf trace becomes joined
to the fifth and sixth, the section of the stele appears circular. In the portion be-
longing to the fifth leaf trace there are present about half a dozen isolated tracheids,
arranged in a row, while in the sixth trace only a single small tracheid is developed.
The two xylems of the fourth leaf trace are now no “longer distinguishable and the
woody part of the trace has the form of an irregular row on ee inner side of the
trace section, and is continuous with the xylems of the fourth and fifth traces.
Even after the fusion of these three traces 1s practically complete, it is still evident
that the ring-shaped section is composed of three parts, the break between the
xylems showing the limits of the three componentleaf traces. With the increase in
the development of the xylem ring the limits of the individual leaf traces are finally
completely lost and the section of the stele shows a thick ring of the tracheary tissue
interrupted only at intervals by single rows of parenchyma cells in the medullary rays.

Outside the ring of tracheids chee can be seen a zone of narrow cells arranged
in radially disposed rows. This zone constitutes a genuine cambium, precisely
similar in appearance to that found in the stems of Conifers and Dicotyledons.
This cambium has long been known to occur in the older sporophytes of the larger
species of Botryc eras and Jeffrey first noted it in the young sporophyte. The

cambium is well developed in the leaf trace for a considerable distance above its
junction with the central stele.

The primary tracheary tissue is in immediate contact with the pith. Occa-
sionally the ring of tracheids is broken by a single parenchyma cell. Outside the
tracheary ring the cells are arranged in radial rows and in these the formation of
the walls is always periclinal, so Wa the cambium in these earlier stages presents a
very characteristic appearance. The rows of cambium cells continuous with the
primary parenchyma cells lying between the tracheids of the primary row do not
develop tracheary tissue, but remain parenchy matous and thus give rise to the
medullary rays, which later are so conspicuous.

The extreme outer portion of the vascular cylinder is composed of a ring of
thick-walled cells which are probably bast fibers, but the walls of these do not stain
strongly with safranine and are hence much less conspicuous than the tracheids.
These may possibly be considered as protophloem elements and evidently corre-
spond to the zone of thick-walled cells figured by Poirault for B. lunarta (Poirault
2, fig. 11). Just outside of this ring of thick-walled cells lies the endodermis, which
has not as yet developed the peamcenene radial thickenings which are so easily
seen in the older parts of the stele. These thick-walled phloem elements, as is the

case with the protoxylems, do not form an unbroken ring, but are interrupted at the
junctions of the confluent leaf traces (fig. 44, C).

In the older bundle, a zone of large cells, the young sieve tubes may be recog-
nized lying inside the ring of bast fibers. Inside of the zone of sieve tubes lies
the E abiein, the cells of which gradually pass into the xylem, to which constant
but slow additions are made from a cambium; indeed, Jeffrey thinks that we can
not speak of primary wood. He considers that all of the wood owes its origin
to the activity of the cambium ring. The radial rows of secondary wood are inter-
rupted at intervals by the medullary rays, and the resemblance of the stele at this
stage to the section of a young coniferous stem is really quite remarkable. The
Bededeanis has now become exceedingly conspicuous, as the lignified lateral walls
stain very strongly with safranine and stand out strongly in contrast with the cells
of the cortex lying outside the endodermis. The inner walls of the endodermal

5

66 THE OPHIOGLOSSALES

cells also stain more or less strongly with the safranine, indicating that they also are
partially lignifed.

The junction of the second leaf trace with the central stele is shown in fig. 43,
E, F, G, and similar stages in the fusion of the first leaf trace are shown in fig.
43; H, 1. The junction of one of the early roots, perhaps the third root, with the
central stele is shown in fig. 43, /. At the level where the second leaf trace departs
from the central stele the xylem ring is composed of about three rows of cells. In
both this second leaf trace and the third the endodermis is very conspicuous upon the
outer side of the bundle, but is not developed upon its inner face. As the trace
approaches the central cylinder it can be seen that the endodermis is interrupted
across the leaf gap, but as the leaf trace approaches, endodermal cells are developed
between the endodermis of the central cylinder and that of the leaf trace. This
union takes place first upon one side, the gap being closed sooner on one side than
the other, but later a similar process takes place on the other side of the leaf trace
and the closing of the gap is complete, the endodermis now being continued without
interruption around the whole of the circular section. The leaf trace where it joins
the central cylinder is exactly like it in size and structure; indeed, it is nothing more
than a sector of the hollow cylindrical stele, which is evidently built up exclusively
of these fused leaf traces. There is no vestige of any tissue in the stele which is not
referable to the bases of the leaf traces themselves. This becomes very evident when
the structure of the leaf trace is examined before it closes the gap w here it joins the
central stele.

An examination of the outer tissues of the older portions of the stem (fig. 42)
show that at certain points there is a conspicuous border of periderm (per), forming
a layer some four or five cells deep. This border of periderm occupies about a third
of the circumference of the section and marks the position of an old leaf base which
has fallen away. According to Jeffrey, this periderm is an ‘‘abciss” layer and
results in the cutting off of the old leaf bases. He suggests that the layer of cork
cells developed from the periderm closes the scar left by the dead leaf and may be
efficacious in preventing infection from fungi in the soil. The presence of a periderm
in the outer cortex of the Ophioglossacee was first pointed out by Russow (Russow
1), and was afterward confirmed by Holle (Holle 1). The periderm in B. wirgin-
tanum is made up of the usual radially arranged rows of cells (fig. 42, per).

All of the tracheary tissue in the young sporophyte is composed of rather short,
reticulately marked tracheids. The secondary tracheids increase in size and the
thickened bars on their walls become broader, so that the larger, elements have their
walls pitted rather than reticulately marked, and these pits, especially in the older
plant, are of the bordered type, not very unlike the round bordered pits found in
the wood of Conifers.

The elongated thick-walled elements in the outer part of the phloem are
probably bast fibers. In the older part of the bundle these stain quite strongly with
safranine and show irregular pits upon their walls. The sieve tubes do not show at
all clearly in sections mounted in balsam. They are evidently large, but the char-
acteristic dotted sieve areas can not be made out and no special study was made of
these. Between the large secondary tracheids and the phloem are the narrow, thin-
walled cambium cells. These probably contribute only to the wood, and there is
no secondary phloem

THE YOUNG SPOROPHYTE 67

THE YOUNG SPOROPHYTE OF HELMINTHOSTACHYS.

The only account that has yet been published of the young sporophyte of
Helminthostachys is that of Lang (Lang 1), who examined at some length the
vascular system in the young sporophyte. Lang states that the young sporophyte
of Helminthostachys develops its first leaf as a large ternate foliage leaf, and when I
frst examined the young plants which were collected in Ceylon I reached the same
conclusion; but on making sections of the young sporophyte it was found that in
all of the young plants that were sectioned the supposed cotyledon was really the
second leaf, the cotyledon itself being rudimentary and forming an inconspicuous
papilla at the base of the second leaf, which was the first to develop a functional
lamina. Further examination of a number of other specimens showed that this
rudimentary cotyledon was also present and it is probable that the cotyledon in
Helminthostachys ys, as in Botr ye hium lunaria and Ophioglossum vulgatum, is always
a rudimentary organ which never appears above the ground.

The youngest sporophytes of Helminthostachys which were found already had
the second leaf well developed and the first root had emerged. The ternate second
leaf (fig. 10, C) shows clearly that the ternate form is the result of an unequal dichot-
omy, such as is common in the early leaves of many ferns. The second leaf of
Helminthostachys closely resembles the cotyledon of Botrychitum virginianum and,
like that, usually possesses two vascular bundles extending through the long, slender
petiole. At the base of the leaf there is a conspicuous stipular sheath which
completely incloses the next younger leaf, as it does in Botrychium lunaria. he two
bundles of the petiole contribute to the two lateral lobes of the leaf as they do in the
cotyledon of Botrychium virginianum, and one of these, forking again, gives rise
Se hoeencanclblobotandisnalleriareral lobe; The venation of the second leaf,
especially in its younger stages, 1s almost perfectly dichotomous and is more like
the venation in the leaves of Botrychium lunarta than that of B. virgintanum. With
the enlargement of the leaf segments the venation more nearly approaches the
pinnate arrangement found in the later leaves.

While the young sporophyte in Helminthostachys in its earliest stages shows a
general resemblance to that of Botrychium virginianum, a difference 1s very soon
noted. The young plant, very soon after the foemeion of the cotyledon, develops
a conspicuous internode between the cotyledon and the root, and the stem rapidly
elongates as the sporophyte grows, so that it soon shows the characteristic elongated
rhizome of the older sporophyte.

Unfortunately I was unable to secure any very young sporophytes, my youngest
specimens already having the second leaf nearly fully developed. According to
Lang, the arrangement of the primary organs of the young sporophyte is the same
as in B. virginianum, but I could make no study of the origin of the vascular system
in the sporophyte before the first leaf and root had emerged from the prothallium.

To judge from longitudinal sections of the youngest plants obtained, the
relation of the first leaf and root is the same as in Boir ychium + virgintanum and the
base of the young sporophyte closely resembles that of the latter. As in Botrychium,
the foot is very ‘large and conspicuous, forming a large, hemispherical body sur-
rounded by the prothallial tissue. The large primary root grows out at right angles
to the foot and is continued into the axis ‘of the sporophyte, which grows up verti-
cally. None of the specimens were young enough to show the relation of the stem
apex to the first leaf and root, as in the youngest specimens the axis had already
begun to elongate and an evident internode was formed between the base of the
first leaf and the root.

68 THE OPHIOGLOSSALES

The longitudinal section of the young sporophyte at this time shows that the
thick stele of the root bends upward and is continued into the axis, which already
is a good deal elongated and has carried up the young leaves, which are separated
from reach other by. conspicuous internodes. ‘The young sporophyte at this stage
thus differs strikingly from the corresponding stages in Ophioglossum and Botrych-
sum, with their very closely crowded leaves with no appreciable internodes between
them (fig. 46).

A single stele extends through the axis from its junction with the root stele and
forks below the insertion of the rudimentary first leaf, one branch passing into the
cotyledon, the other continuing upward and forming the trace for the second leaf,
at whose base is seated the apical bud.

Whether in the younger stages, before the development of the second leaf, the
vascular system of the young sporophyte would show the same relations of the steles
of the root and coty ledon, as in Botr ychium, remains to be seen; but from the general
similarity in the structure of the young sporophytes of the two this is quite likely:
yet it is possible that the stem apex is
more prominent in the early stages of
Helminthostachys and part of the stele
which is found in the elongated stem

may be of cauline origin, although this
is hardly indicated by the condition of
things in the apical meristem of the
youngest sporophytes that were ex-
amined.

The foot is composed of large-
celled, thin-walled parenchyma, with
no noticeable differences between the
inner tissue and that of the periphery.
The stele of the root is continued up-

ward without interruption into that of
the shoot (fg. 46, B). Probably at an
earlier period there would have been,
as in Botrychtum, simply the continu-
ous stele of the root and cotyledon.
At the junction of the root stele with

Fic. 45. J
\. Young sporophyte of Helminthostachys, attached to gameto- that of the axis there is a marked en-
phyte, pr. cot, cotyledon; r*,r*, first and second roots. X 2. largement, and the short, somewhat tr-

B. Leaf from an older sporophyte. X1.

regular tracheids are decidedly broader
than those either in the root or in the portion of the stele above the junction. The
tracheids toward the outside of the central region are slender and have delicate
reticulations, which closely approximate the form of true spiral thickenings. These
are the protoxylem elements and can be traced upward and downward into the
stem and root, respectively. The secondary tracheary tissue is marked by broad,
reticulate thickenings, and these in the largest tracheids are replaced by conspicu-
ous oval or nearly round bordered pits, very nreitel like those which are found in Bo-
trychium (fig. 46, E).

Above the base of the root there is a long internode below the coty ledon, and
through this runs the single axial stele. On the same side of the axis as the primary
root may be seen the cotyledon, which closely resembles in form the young cotyledon
of Botrychium virginianum, but instead of developing into a functional leaf it is
arrested in its growth before the lamina is fully developed. As in the cotyledon of

THE YOUNG SPOROPHYTE 69

Botrychium virginianum, the lamina, which although very greatly reduced never-
theless is present, is bent over sharply against the stout petiole, which is strongly
convex on its adaxial side. In the specimen figured there was no trace of a stipular
sheath developed in the cotyledon, but sometimes this is very well developed,
although the upper part of the cotyledon remains quite rudimentary. The little
cotyledon has the rudimentary lamina distinctly ternate in outline and very much
resembles some of the rudimentary early leaves found in Botrychium lunaria, as
figured by Bruchmann. A single vascular bundle extends through the petiole of the
cotyledon, nearly to the base of the lamina, but except in the basal region the
development of the xylem is much reduced and is entirely lacking before the lamina
is reached. The bundle of the cotyledon, where it bends at the base into the inter-
node, is nearly as well developed as the bundle of the second internode which
separates from the former just below the insertion of the cotyledon. On the opposite
side of the second internode from the cotyledon, and extending downward through
the first internode for a short distance below the level of the cotyledon, there is seen

A, B. Two longitudinal sections of a young sporophyte of Helminthostachys; pr, gametophyte. 6.
C. Upper part of same, more enlarged; b, terminal bud; cot, cotyledon; i, lacuna in first internode.
D. Apical region. /*, third leaf; sc, epidermal scales. X140.

E. Tracheids showing bordered pits and thickened bars. 320.

in the specimen figured a large lacuna, separated from the outside of the internode
by about half a donee layers of cells and on its inner side from the endodermis of the
stele by two or three layers of cells. This lacuna, as Lang pointed out, is not alw ays
present. At the upper end of the second internode can be seen the base of the second
leaf, the stipular sheath of which incloses the young bud at the summit of the axis.
On its inner (dorsal) side the terminal bud shows the young third leaf, opposite
which is the section of the ridge surrounding the small free punbice of the stem apex,
very much like the condition in the young bud of Ophioglossum moluccanum.
The form of the young leaf at this stage 1s more like that of Botrychium lunaria than
that of B. virgintanum. The young ‘leaf is a blunt cone with a marked projection
on its inner Side. extending over the apex of the stem and marking the beginning
of the stipular sheath, which is entire as in B. lunaria, and not dumatiedh into two free
stipules as in B. wirginianum (fig. 46, D). A conspicuous strand of procambium
extends into the leaf and joins the trace of the second leaf. As in Botrychium and
Ophioglossum, the stele of the internode does not extend upward beyond the base of
the youngest leaf and there is no indication that it derives any of its tissues directly

70 THE OPHIOGLOSSALES

from the apical meristem of the shoot. ‘The latter, as in the other Ophioglossacex,
shows a large single initial cell, which in section closely resembles that of Ophro-
glossum moluccanum, having a broadly truncate base and being narrower above
(fig. 46, D). The apical meristem is of very limited extent and segmentation of the
apical cell is probably very slow. ‘The second root, which in the case under con-
sideration arose near the base of the third leaf, is here very conspicuous and its stele
joins that of the third leaf near the base of the internode. The young leaf and root,
with the inconspicuous stem between them, have very much the appearance of a
bud at the base of the second leaf. The apex of the very young leaf grows from the
conspicuous single apical cell (fg. 46, D). This appears triangular in longitudinal
section and shows regular segmentation. ‘The stele of the young leaf can be traced
up to the inner cells, cut off from the lateral segments of the apical cell.

The apical cell of the stem is quite large and, as we have seen, is truncate below,
as it is in Ophioglossum. Seen in its transverse section it is triangular, so that its
form is really that of a three-sided prism. Both lateral and basal segments are cut
off from it, but only the youngest segments can be clearly distinguished. Below the
apical cell there is only a very small amount of tissue between the apex of the shoot
and the point of the junction of the two leaf traces and the stele of the second root.
This junction is marked by the presence of very irregular reticulate tracheids (fig.
46, D,tr). The tissues on the upper side of the root stele extend to within a few cells
of the stem apex and may possibly
represent a portion of the internodal
stele that is not connected with the
leaf trace, but a study of later stages
does not support this view, and it
is almost certain that this youngest
tracheary tissue is the beginning of
the next leaf trace.

From the very first, as Lang
pointed out, the shoot is perfectly
dorsiventral, although at first it grows
vertically upward. The leaves are all
borne upon the dorsal side, while the
roots invariably arise upon the ven-
tral side.

The apex of the young root,
Fic. 47-—Transverse section of young sporophyte of Helminthos- which in this case is on the point of

tachys, above terminal bud. /',/?, lacunae; /*, second leaf. X65. emerging, ie occupied by 2 conspicu-
ous triangular apical cell, the segmen-
tation of which closely resembles that
of the root of Botrychium. At first the root cap is mainly derived directly from the
outer segments of the apical cell. These segments undergo periclinal as well as
anticlinal divisions and the inner layers of the root cap (which at this stage is rela-
tively thick) show a fairly regular stratification. The outer cells of the root cap are
a good deal elongated, so that the free end of the root is decidedly pointed. At this
time, except for the irregular conjunctive tracheids at the base, no permanent tissue
can be seen in the stele of the young root.

In the cross-sections of a young sporophyte of about the same age the third leaf
was rather further developed and the young fourth leaf could be seen, but the second
root was not so far advanced, or it may be that the root at the base of the third leaf
was the third root and not the second. ‘The single apical cell, which was so prominent

B. Section passing through base of bud. r, young root. X100.
C. Stem apex. 200.

THE YOUNG SPOROPHYTE 7A

in the very young leaf, can no longer be recognized and the lamina is divided into
two nearly equal lobes, of which one is lateral with reference to the other, but these
two lobes probably arise as a result of the dichotomy of the original apex. A group
of narrow marginal cells somewhat to one side of the terminal lobe evidently consti-
tuted a meristem tissue, and this was preparing for the second dichotomy, by which
the ternate form of the young leaf is established. The branching of the lamina at
this early period therefore appears to be the result of an unequal dichotomy, as it is
in the first foliage leaf. The vascular bundles from each of the two primary leaf seg-
ments were just beginning to be recognizable and join into one at the base of the
lamina. Surrounding the leaf is the sheath developed from the base of the second
leaf. This sheath in the section appears as a closed ring some two or three cells in
thickness and looking very much like the sheath of Ophioglossum. The top of the
conical sheath is closed and does not show the pore found in Ophroglossum. The
sheath becomes thicker lower down, where four rows of cells show in the section.
Between the inclosed leaf and the surrounding sheath in the lower portion (fig. 49, B)
may be seen the section of flattened scales (sc) which grow from the base of the leaf

Fic, 48.

A, B. Two sections of terminal bud of a young sporophyte of Helminthostachys.
C, D. Two similar sections from an older plant. x, stem apex; sh, petiolar sheath.

and from the tissue immediately about the stem apex. At its base the sheath of
the third leaf is already completely developed and surrounds the young fourth leaf
(+), which in this section was cut horizontally and shows plainly its large apical cell.
The stem apex, which lies directly below the younger leaf, was cut obliquely in this
series and did not show the form of the apical cell plainly, but in a young plant of
about the same age (fig. 47, C) the apical cell showed that it was regularly trian-
gular in form, seen in cross-section.

At the level of the stem apex the second leaf shows a single vascular bundle
which may be continued undivided upward, or it may divide into two bundles in the
petiole. In regard to the structure of the petiole, therefore, Helminthostachys is to
some degree intermediate between Botrychium and Ophioglossum. The young trace
of the third leaf can be seen at this level as an oval mass of undifferentiated cam-
bium. Immediately below the stem apex the cells are smaller than ts the case in
the young sporophyte of Botrychium, but one can not make out the beginning of a
central procambium cylinder. The smaller cells in the region immediately underlying
the stem apex may be explained by the fact that in these young plants there is no
pith developed within the axial stele as there is later on. The youngest root in this

To = =

72 THE OPHIOGLOSSALES

specimen was less developed than that in the specimen that we have just described.
This youngest root was cut obliquely, but at its base there could be seen the undif-
ferentiated mass of procambium forming its stele, and the apex showed the tetra-
hedral apical cell, presenting much the same form as the longitudinal section. The
apical portion of the young root was somewhat shrunken away from the surrounding
tissue, so that there was a very evident space surrounding it. Whether or not this
was the result of artificial shrinkage was not certain.

Below the terminal bud the third leaf trace proceeds downward into the inter-
node below, and the tracheary tissue, which is just beginning to develop in the bud
region, increases rapidly in amount and forms a central mass of wood which does

Fic. 49.—Ten cross-sections from a series of a young sporophyte of Helminthostachys. X25.

C. Passes through the stem apex, x. The round shaded cells are tannin sacs.
D. Shows the narrow pit, y, between the leaf base and the axis.
G-J. Show only the vascular bundles.

not appear solid, but is made up of two groups of tracheids, of which the one nearest
the second leaf trace has the larger tracheids. At this stage the bundle somewhat
resembles the section of a diarch root. Only a little farther down the two xylem
masses are joined by the development of tracheids in the middle of the bundle,
which thus comes to have a solid xylem core. In the section figured there may be
seen a single small isolated tracheid on the side turned toward die second leaf trace,
which has now approached so close to the central bundle as to touch it (fig. 50, 4).
The central bundle in the internode at this point is beyond question the leaf trace for
the third leaf. There is no difhculty in tracing its progress upward to where it enters
the leaf and there is no sign of any addition to it from tissue lying outside the
original leaf trace. “The central stele of the upper part of the second internode is
throughout nothing more than the basal portion of the leaf trace from the third leaf.
At this point it is concentric in structure. Surrounding the solid xylem core can be
seen about three rows of phloem cells, some of the outer ones being small protophloem
elements. The large ones lying inside are presumably sieve tubes. A single layer
of rather large pericycle cells separates the phloem from the large endodermal cells,
which begin ¢ to show very conspicuously lignified radial thickenings, especially on
the side of the bundle adjacent to the second leaf trace. The section of the second
leaf trace is somewhat extended transversely and the xylem band is composed of
about a dozen tracheids. In the mid region of the section the xylem is separated
from the inner side of the bundle by a single layer of cells, possibly sieve tubes, but
at one point the xylem 1 is in contact with the pericycle, which is only imperfectly
developed and wanting at certain points. Upon the dorsal side the phloem may
be in direct contact with the endodermis, which is quite wanting at this point upon
the ventral side of the bundle. Higher up, where the trace is quite free, the endo-
dermis extends completely around it. While the second leaf trace, therefore, may

THE YOUNG SPOROPHYTE 13

be said to be concentric, it nevertheless approaches closely the collateral type of
the other Ophioglossacez.

The fusion of the two leaf traces to form the single axial bundle in the basal
part of the internode is very much like that found in the young sporophyte of Bo-
trychium (fig. 49, D, F). The endodermis of the two bundles becomes continuous
and there may be seen intermediate stages of a single bundle, oval in section, but
with two conspicuous xylems, separated by the mass of large, thin-walled tissue
which gradually disappears as the bundle is followed downward; and finally, in the
lower part of the internode, the section of the stele appears quite circular, the center
being occupied by the solid xylem formed by the complete coalescence of the xylems
of the fused leaf traces (fg. 49, /). The arrangement of the phloem, pericycle, and
endodermis is the same
as in the single leaf trace
in the upper region of the
internode.

The base of the stip-
ular sheath can be fol-
lowed downward to about
the level where the two
leaf traces begin to coal-
esce. Its anterior free
portion, between which
and the internode is a
narrow slit, finally be-
comes quite free and its
section is visible as an

oblong mass of cells lying Fic. 50.

quite separate from ae Two sections of the vascular bundles from the series of Helminthostachys shown in

section of the inter node. fig 49, showing junction of two leaf traces to form central stele. en, endoder-
mis. X150.

Longitudinal sections
of a sumer ee older sporophyte are shown in fig. 48, 4, B; the third leaf is pretty
well developed, with the stipular sheath completely overarching the stem apex and
the fourth leaf, which already is conspicuous. The third leaf is still completely
covered by the large stipular sheath of the second leaf, which apparently forms a
closed cavity; but ; an examination of the adjoining sections showed that the ante-
rior margin of the sheath 1s quite free in front and that there is a narrow cleft
between it and the internode. ‘The real nature of the sheath and its relation to the
leaf base is very clearly shown in the median section of the terminal bud from an
older plant (fig. 48, C, D), and the resemblance to the terminal bud of Botrychium
lunaria, except for the dorsiventral arrangement of the parts, 1s most striking. ‘This
is equally marked in the adult sporophyte, as Farmer has already pointed | out.

The specimen under consideration differed somewhat from the younger one
that was described in the relation of the young organs. ‘The cotyledon was better
developed and although the lamina was rudimentary the stipular sheath was large
and inclosed the base’ of the second leaf, while in the younger specimen Tears
no sheath was developed at the base of the cotyledon. ‘There was a different rela-
tion of the roots also, probably associated with the greater development of the
cotyledon in the specimen under consideration. The second root, instead of being
formed at the base of the third leaf in the terminal bud, was developed a short dis-
tance above the cotyledon, near the base of the second leaf, while in the younger
specimen no root was developed above the primary root until the third leaf had

74 THE OPHIOGLOSSALES

begun to develop; but this second root developed much earlier in its relation to the
development of the next leaf than was usually the case.

In the present plant the root corresponding to the third leaf, which was the
third root in this case, was in a very early stage of development and had not begun
to elongate at all. ‘The third leaf in median section was already pretty well advanced
and the apical portion was very strongly incurved, as it is in the young leaves of
Botrychium virginianum, which it resembles more than it does that of B. lunaria,
and it also suggests the form of the young leaves in the Marattiacew. The basal
part of the young leaf, however, is exactly like that of B. /unaria. The stipular
sheath forms a thick body, projecting forward and about equal in height to half the
total length of the young leaf. It is strongly concave below, and the next leaf is
fitted into the cavity (fg. 48, C). The forward margin extends downward as a sort
of lip which elongates rapidly and keeps pace with the growth of the young leaf
inclosed within it, and this is completely concealed until it has reached a large size.
The sheath finally forms a long, conical protuberance at the base of the leaf to which
it belongs.

The cavity below the sheath is extended backward, so that the base of the leaf
is hollowed out in front and in section appears much narrower than the part of the
petiole above the insertion of the sheath; this brings the stele of the leaf very close
to the epidermis at this point. The narrow cleft thus formed between the posterior
wall of the stipular cavity and the petiole of the leaf in front is the “canal,” which
Gwynne-Vaughn described as occurring at the base of the petiole of the older plant
and opening above the insertion of the stipule. These canals are easily seen in longi-
tudinal sections of the young bud (fig. 48, B) and it is very clear that they are, in truth,
nothing but the narrow spaces between the bases of the adjacent leaves. Gwynne-
Vaughn’s statement that they open above the insertion of the stipules is incorrect
unless the stipules of a given leaf are considered to be derived from the sheath sur-
rounding the base of the leaf, this sheath properly belonging to the next older leaf.
This canal can be seen as a narrow slit in the young leaf, extending below the inser-
tion of the next younger one, the young stele of the leaf being separated from the
epidermis at this point by only about three rows of cells.

The stele of the young leaf can be traced nearly to its tip, and then continues
downward toward the inner side of the leaf into the internode, below where it joins
the young stele belonging to the next younger leaf.

As in the younger sporophyte, the stem apex is of very limited extent and the
apical cell shows the same form. In the section fgured (fg 48, C) the youngest leaf
is cut almost in a median plane and though externally no differentiation is visible the
young stele is already conspicuous and can be followed down without difficulty.
Passing on one side of the stem apex and above the leaf trace, there is no evidence of
procambium i in the apical region of the stem. In the young sporophyte, therefore, it
is perfectly certain that no cauline stele is present. Farmer (Farmer 2) states that
in the older sporophyte the stele can be traced above the insertion of the youngest
leaves, but we believe a careful study of this point in the older plant would show, as
in the younger one, that the stele is developed in the young leaf at an exceedingly
early period and that the stele of the internode is composed entirely of leaf and root
traces. The procambium tissue developed on the ventral side of the stele near the
apex can be shown, by a study of its transverse sections, to be due entirely to tissue
derived from the leaf traces, which are extended downward until they meet on the
ventral side of the internode.

Near the stem apex are numerous small scales and hairs filling up the space
about it and probably associated with the prevention of drying up of the stem

THE YOUNG SPOROPHYTE 75

apex, which is doubly protected by these scales and its complete inclosure in the
young leaf bases. It is possible that these scales secrete some mucilaginous sub-
stance, although there was no evidence of this in the stained sections.

In this plant the internodes were quite solid and there was no trace of the large
lacune which were described for the younger plant. Whether the presence of the
lacunz is due to-any differences in the environment remains to be seen. The speci-
mens were all collected under apparently the same conditions, but it is possible that
there may have been differences in the amount of water in the soil in which they were
growing, and this difference in the amount of water may have something to do with
the development of the lacunz.

The root at the base of the third leaf was cut transversely and was in a very
early stage of development. The root was still completely buried in the cortex and
the stele still imperfectly developed, but showing its connection with the stele of
the fourth leaf above the junction of the third leaf trace with the stele of the inter-
node. No tracheary tissue was developed and the course of the leaf trace was but
little disturbed by the formation of the root.

In longitudinal sections taken from a much older sporophyte (fig. 48, C, D)
the arrangement of the organs at the apex is seen to be exactly the same as in the
younger plants, but of course the parts were all larger. The youngest leaf (/" ) still
resembles in form and size the corresponding leaf in the younger stem, but the next
older leaf is relatively broader than the early leaves of the younger sporophyte, and
although the stipular sheath is now well developed the upper portion of the leaf
is still quite undifferentiated and the apex is scarcely bent forward at all. The
resemblance, therefore, to the young leaf of Botrychitum lunaria is even more
marked than it is in the younger sporophyte. The apical region of this young leaf
is occupied by an epithelium-like layer of columnar cells, and it is doubtful whether
any one of these can be certainly denominated the apical cell. Somewhat the same
doubt exists also as to the point of a single initial cell in the youngest leaf. In the
latter there was some shrinkage in the group of large meristem cells at the apex,
which made it still more difficult to decide this point, but a median section showed
somewhat indistinctly a single cell, apparently triangular in outline, which from its
form and the arrangement of the adjacent cells may very well have been the apical
cell. The small group of meristem cells forming the stem apex is crowded in between
the base of the youngest leaf and the elongated ridge which surrounds the stem apex
upon the ventral side. In consequence of this crowding the outer faces of the
apical cell and its youngest segments are very small. The base of the apical cell
is more than twice as broad as its free outer face. The ventral face of the apical
cell is convex and the young segments cut off from it are strongly curved. The inner
or basal wall is oblique, so that the axis of the young cells in the tissue below the
apical cell makes an angle with the long axis of the apical cell.

Below the apical region may be seen the section of the large central stele of the
internode. This is composed, apparently, of two strands of procambium separated
by a broad band of pith. As Farmer pointed out, in the older plant there is no
question that procambium tissue is developed upon the ventral side of the bundle
which extends into the apical region and which is, apparently, not connected with
the leaf traces. From this he believes that the stele is really a cauline structure.

A study of the cross-sections, however, as will be presently seen, shows that
this ventral tissue really does belong to the leaf traces, although it is possible that
the basal tissue of the roots may add to it in part, but I have not been able to
satisfy myself that any of this stelar tissue can be properly assigned to the activity
of the stem apex.

76 THE OPHIOGLOSSALES

As in Botrychium and Ophioglossum, the tissue derived immediately from the
activity of the apical meristem, after the central pith is developed in the stele,
contributes only to this central region or pith, which is really not part of the stele
proper. On the dorsal side of the stele the whole of the procambial strand can
easily be followed into the leaf, and when this is followed downward it is seen to
run obliquely through the youngest internode, at the base of which it joins the next
leaf. The latter already has its lamina developed and strongly bent over, but is
still inclosed in the stipular sheath belonging to the next older leaf.

These older leaves have only a single leaf trace, but it divides into two strands
above the level of the stipular sheath. A median section of the thick central stele in

Fic. $1.

Seven transverse sections from a young sporophyte of Helminthostachys. X35. 1, petiole of leaf;
&, terminal bud inclosed by stipular sheath, sh. In G, x is pit between leaf base and internode.
H, section of a young leaf, showing the ternate lamina.

the upper region shows conspicuous protoxylem elements made up of much elongated
tracheids, whose thickenings are between annular and spiral in form, but very
different from the coarsely reticulate and the conspicuously pitted tracheids of the
metaxylem developed in the older parts of the stele. In all cases where truly median
sections were seen the protoxylem elements occupied the innermost region of the
xylem and no metaxylem was seen within these, so that the bundle (at first, at any
rate) is endarch, as in the other Ophioglossacez. It is impossible to see in this sec-
tion that metaxylem was developed inside of the protoxylem, as Farmer found to be
the case in the older sporophytes.

THE YOUNG SPOROPHYTE fell

In fig. 48, D, there is shown an insertion of a root upon the stele and its very
broadly expanded base with the irregular conjunctive tracheids. This very broad
base of insertion and the obvious continuity of the tracheary tissue of the root with
that of the central stele of the stem suggest that the ventral part of the stele might
be made up, in part at least, of root traces.

Cross-sections of older plants, such as that shown in the series indicated in
fig. 51, show essentially the same arrangement of the parts as do the younger ones.
At the apex there may be seen in section the three youngest leaves, which we will
designate respectively 1, 2, and 3, No. 1 being the Bide seicaehe wee illncingiceeion
the oldest leaf shows two vascular bundles in the petiole, and this is true also of the
second leaf, which is contained within the stipular sheath of the oldest leaf. The
lamina of leaf No. 1 already shows the characteristic ternate form. The young
leaves make an angle of about 30° with each other. Section B passes directly through
the stem apex and shows the sections of the basal part of the sheath of the two Slee
leaves. The stipular sheath of the youngest leaf partially incloses the stem apex,
and surrounding the apical region is a loose mass of cells, derived partly from the
tissue immediately around ie stem apex and partly from the edges of the sheath
of the youngest leaves. These cells are really sections of hairs and scales which
perhaps secrete mucilaginous matter, but there was no evidence of this in the sec-
tions. Turned toward The dorsal side of the section may be seen the leaf trace from
the second leaf and separated from it by a considerable space on the ventral side
is a rather vaguely defined mass of young procambium, which marks the trace of
the youngest leaf. On the ventral side of the latter is the stem apex itself. Further
down, as has already been described for the younger stem, the two leaf traces approach.
At the level of the stem apex the trace of the second leaf is clearly defined and
nearly oval in outline, but more convex upon the dorsal side. The bundle is inclined
toward the side of the stem opposite the insertion of the first leaf. Further down
the trace becomes much broader, this being mainly due to the development of the
tissue upon one side, which begins to bend dee nward toward the ventral side of the
stem. The trace of the youngest leaf is now somewhat better defhned and appears
somewhat kidney-shaped in section, the convexity, like that of the second leaf trace,
being turned toward the dorsal side. This trace also begins to show the extension
of tissue toward the ventral side of the stem and this is dev eloped on the side opposite
to the extension in the next older leaf trace. Ultimately these ventral extensions of
the two bundles meet as the two leaf traces come nearer together, and the dorsal
ends also finally come into contact, so that the two bundles, the section of each of
which is approximately semicircular, form a complete ring inclosing a greater or
less amount of the ground tissue, which thus forms the pith of the halite ele The
stele resulting from the union of the two leaf traces is not at first perfectly circular
in section, but shows plainly for a long time that it is composed of two separate
bundles (fig. 51, F).

The first development of permanent tissue in the older leaf trace is evident
before it joins the younger one. The first elements are thick-walled cells (which
may be called protophloem) i in the outer zone of the phloem, and a little later at the
inner limit of the bundle a small group of protoxy lem elements appears. Very soon
after this a similar differentiation takes place in the younger leaf trace, so that when
the two leaf traces are completely fused the protoxylems have the appearance of
having arisen toward the central part of the bundle, but in reality the component
bundles, at least at their earlier stage of development, may be described as endarch
and agree, therefore, with the bundles of the other Ophioglossacez. In the leaf
traces of the older part of the stem, however, there may generally be found inside

78 THE OPHIOGLOSSALES

the protoxylem a few scattered, large tracheary elements, so that the bundle may be
said to be mesarch, as Farmer states is the case in the older rhizome.

During its earlier stages the stele shows no leaf gaps where the leaf traces
depart, and the leaf gaps are only gradually developed. Soon after the stele has
assumed the form of a hollow cylinder the leaf gaps are for some time absent, or
they are developed only in a very small degree and close almost immediately upon
the departure of the leaf trace.

In none of the young plants that I examined could I detect any of the inner
endodermis which occurs in the older rhizomes. Farmer, however, states that the
inner endodermis is only imperfectly developed and concludes that it is the result
of the invagination of the outer endodermis through the leaf gap; or, to put it in
another way, it is the persistence of the inner endodermis of the leaf traces of which
the hollow stele is made up. The bundle at this stage most nearly resembles that of
Botrychium lunaria, differing from that of B. virginianum in the absence of a true

fg ° ‘4
S, HO as = “Sas Ps
£ TO aKa) a - Reg

A. Section of the young central stele of He/minthostachys, showing the two xylems. 200.
B. Stele from lower part of an older sporophyte, showing junction of a leaf trace with central stele. 50.
C. Part of central stele, more highly magnified.

cambium, the outer wood cells being directly in contact with the inner cells of the
phloem. Occasionally, however, there may be seen on the outer edge of the xylem
ring a few imperfectly developed tracheids which probably represent a very rudi-
mentary development of secondary wood, but there is no other sign of the definite
cambium zone which is so conspicuous in the stele of Botrychtum virginianum.
From this study of the development of the leaf traces, following them from the
stem apex downward, it appears that the cylindrical stele in Helminthostachys
arises in precisely the same way as that of Botrychrum, viz, by the union of the leaf
traces. The appearance of procambium upon the ventral side of the stele, which
in longitudinal section appears to be derived directly from the stem apex, can thus
be explained by the ventral extension of the broad leaf traces which meet on the
lower side of the stem as well as above, and the cylindrical stele is thus developed.

THE YOUNG SPOROPHYTE 79

It is not impossible that the root traces may also contribute to some extent to the
development of this ventral portion of the stele. The xylem masses belonging to the
two leaf traces remain quite distinct for a long time, the one belonging to the older
trace being better developed than that from the younger one (fig. 52, 4). The
metaxylem consists of scattered tracheids arranged regularly in an arc outside the
protoxylem of the older bundle, but there are a few scattered smaller ones lying in
the tissue separating the two primary xylems, so that, as we have seen, the bundle
may perhaps be described as mesarch, and not endarch as it 1s in Ophroglossum and
Botrychium.

The two xylems of the separate bundles are finally connected by intermediate
tracheary tissue, so that a nearly complete ring of wood 1s formed, but the xylem of
the older leaf trace is still clearly recognizable on account of its greater thickness.
In the section figured (fig. 52, C) there is no tracheary tissue yet formed inside the
protoxylem and there is a well-marked pith occupying the center of the stele. The
endodermis is now well developed and inside it are about two rows of pericycle cells.
The protophloem is less conspicuous than in the younger stele and is best developed
in the outer portion of the older leaf trace. The rest of the phloem is made up of

Fic. 53.

A. Transverse section of apex of first root of Helminthostachys, showing a
single tetrahedral apical cell. 200.
B. Apex of a later tetrarch root, with apparently no single initial cell.

thin-walled cells, the larger of which are presumably young sieve tubes. The section
is taken from a much older part of the stem and shows that the bundle has attained
practically the same condition as in the adult stem, except for the absence of the
inner endodermis. ‘The central pith is surrounded by an unbroken ring of wood,
averaging about three cells in width. The outer part of the bundle is essentially
the same as in the one that has been described.

The canal described by Gwynne-Vaughn for the older sporophyte is plainly
evident here and extends backward from the sheath cavity, appearing in cross-
section as a narrow cleft between the inner side of the leaf stalk and the internode
(fig. 49, D, y). It is evidently not a cavity in the cortex, but merely an invagination
of the epidermis, which is continuous with that of the inner surface of the stipular
sheath.

A peculiar feature of the ground tissue in the young stem and petiole in Helmin-
thostachys is the presence of cells containing roundish bodies which stain very
strongly with Bismarck brown, and these cells closely resemble the tannin cells of
the Marattiaceae, with which they are probably homologous (fig. 49, C). Lang

figures these cells (Lang 1, fig. 65), but makes no mention of them in his text.

SO THE OPHIOGLOSSALES

The trace for the second leaf, the first functional one, is usually provided with
a single undivided bundle passing through the petiole, but sometimes this divides
into two, as it does in the cotyledon of Botrychium virgintanum. Where a single
bundle occurs in the petiole it occupies a nearly median position and is concentric
in structure, although the phloem is somewhat less developed upon the adaxial side.
The xylem consists of a large mass of tracheids surrounded by the phloem, which is
reduced to about two rows of cells upon the adaxial side. Whether the largest cells
in this portion were sieve tubes was not determined. Where two bundles are present
they are somewhat smaller and are more nearly circular in outline than the single
bundle, which they resemble in structure. In the ground tissue are large inter-
cellular spaces which disappear at the base of the leaf, where the ground tissue in
cross-section appears almost solid. ‘This development of lacunz in the first foliage
leaf recalls the similar ones in the cotyledons of Botrychium and Ophioglossum.

In the older part of the rhizome there ts a slight developme nt of periderm on the
dorsal side, which Farmer found to be the case also in the older rhizome. This
periderm is restricted to the dorsal region and is obviously associated with the leaf
bases, as it is in Botrychium and probably also in Ophioglossum. It presumably

Fic. 54.

Three sections of an older sjorophyte of Helminthostachys. X8. The stipular
sheath is absent from the third youngest leaf.

acts as an absciss layer, such as Jeffrey demonstrated in Botrychium, and this not
only causes the separation of the old leaves but perhaps also acts asa protective
layer to the leaf scars. The absence of periderm from the ventral side is no doubt
connected with the strictly dorsal position of the leaves.

The later roots, like the first one, grow from a single tetrahedral apical cell,
very much like that of Ophioglossum and Botrychium. The root cap is not very
prominent and is usually somewhat pointed. It apparently owes its origin entirely
to the activity of the outer segments of the apical cell. The primary segments of
the root cap undergo periclinal divisions, but, as in Botrychium, the stratifications
of the older layers is much less marked than it is in the ordinary ferns. Each of
the lateral segments of the apical cell divides by a somewhat radially placed anti-
clinal, so hae a transverse section of the three youngest segments shows six cells
having a nearly radial arrangement. Periclinal walls may arise and the inner cells of
the segments give rise to ihe central cylinder of the root, while from the outer ones
is developed the cortex. As in the other Ophioglossacez, no root hairs are formed.

THE YOUNG SPOROPHYTE Sl

The primary root, as Lang pointed out, is usually triarch, but occasionally
diarch roots occur, as they usually do in Botrychium and in Ophioglossum pendu-
lum. In this case, however, one of the xylems was rather larger than the other.
The later roots are tetrarch and in the older sporophyte, as Farmer showed, the
roots generally have six xylem masses, or occasionally seven. ‘This type of root is
most like that of the Marattiacea. The endodermis is pretty well dey eloped, but
not so conspicuous as it is in Botrychium.

In the cortical region of the first root there is a zone of cells in which occurs an
endophytic mycorrhiza, such as is common in the roots of other Ophioglossacex,
and probably the same as the endophyte which is found in the tissue of the prothal-
lium. Whether the infection of the primary root is direct from the prothallium or
whether there is a new infection from the soil was not determined. Lang states
that the mycorrhiza is only developed in the first two or three roots, the fourth root
and those formed later not having the endophyte. In these later roots the cortical
cells are densely filled with starch.

The rhizome continues to grow upright for a good while and it was not deter-
mined at just what time it assumes the prostrate position which it has in the adult
form. At first there is usually one root formed for each leaf, but in the older plants
this regularity is lost, and Farmer states that there may be three or four roots
developed for a single leaf. On the other hand, the number of roots may be less
than that of the leaves, especially in the younger plants.

A curious abnormal form was seen in a young sporophyte, where for some reason
several of the earliest leaves had remained in the rudimentary condition of the cotyle-
don. Five of these rudimentary leaves could be seen formed in succession. The
sheaths were fully developed and there was a long internode between each pair of
leaves. Three of these had developed roots, but the others had failed to do so. This
rhizome was nearly 3 centimeters in length, but it had hardly increased at all in
thickness. A single ternate leaf had expanded at the summit, but whether this
was the first functional leaf that the plant had developed could not be determined,
as the rhizome was broken off below and there may have been one or more func-
tional leaves developed below the first of the rudimentary ones.

This repetition of vestigial leaves recalls the condition of things in Ophioglossum
vulgatum and Botrychium lunaria. For a good while the new estes are of the same
ternate form as that of the first foliage leak but sooner or later, probably depending
on the vigor of the plant, the ternate one is gradually replaced by five foliate leaves,
the later divisions being the result of an unequal dichotomy of the lateral leaf seg-
ments, similar to that by which the second lateral segments of the primary leaf are
separated from the terminal leaflet. In these five foliate leaves the characteristic
“pecopterid” venation of the adult sporophyte is fully attained (fig. 45, B). Each
lateral vein forks twice, the ultimate veinlets extending to the margin of the leaflet.
A section of the petiole of one of these leaves shows that it contains four vaseulat
bundles, arranged in pairs. The dorsal bundle of each pair is decidedly larger than
the ventral one. The base of the petiole is almost perfectly cy lindrical, but further
up it becomes winged, so that a groove appears on its inner face extending for some
distance below the junction of the lamina and the petiole. There is a very slightly
developed hypodermal tissue composed of two or three layers of cells, the walls of
which are colorless and considerably thickened, some of them showing thickened
comers like the collenchyma found in the leaves of the Marattiacee.

82 THE OPHIOGLOSSALES

COMPARISON OF THE YOUNG SPOROPHYTES OF THE OPHIOGLOSSACE4.

If, as we believe, the type of sporophyte found in Ophioglossum moluccanum
is really primitive, we may assume that the sporophyte at first had a single axial
stele, collateral in structure and essentially the same in leaf and root. This primitive
sporophyte had no stem at all, but consisted simply of leaf and root. From the
primitive vascular skeleton, composed of a single unbranched strand, we can derive
the different types characteristic of the older sporophyte in the three genera. As
to the first origin of the stem apex, we can only conjecture; whether it originally

arose, as it does in Ophroglossum, as an endogenous structure repeating, as it were,
the origin of the primary root, we have no means of knowing, but this seems to be
the most probable explanation of the origin of the stem apex in the primitive sporo-
phyte from which are descended the different types of the Ophioglossacee. After
the establishment of the stem apex the secondary leaves contributed their quota to
the developing skeleton of the sporophyte. In Ophroglossum these leaf traces remain
largely free and anastomose only to a limited extent, thus giving rise to the open
tubular dictyostele with very large meshes. ‘The structure of the individual strands
of the dicty ostele is essentially the same as that of the free leaf traces.

In Helminthostach ys the early leaf traces fuse completely and there is formed
a solid stele in the younger internodes with a central xylem core, composed of the

united xylems of the two leaf traces. These leaf traces are approximately collateral
in structure, although it may be that they have a small amount of phloem upon
their inner face. After entering the petiole of the young leaf, however, these assume
a distinctly concentric form. As the leaves increase in size their traces become
broader and in section appear more or less crescentic, so that when the leaf traces
come together there is left between them a certain amount of the ground tissue which
after they have united appears as a pith lying inside of the tubular stele. This
pith, however, it must be remembered, is not part of the stele proper, but is merely
an included portion of the ground tissue. With the complete fusion of these two
broad leaf traces the tubular form is established and the wood appears in section
as a continuous ring. In Botry« ‘hium, especially in the large forms like B. virgin-
ianum, the tubular condition which is secondary in Helminthostachys i is established
at once; this is probably to be explained by the fact that the vascular bundles of
the first leaves are much better developed, there being two strands in the cotyledon
and in the second leaf, and the leaf traces belonging to these are correspondingly
broad and on fusing include at once a certain amount of the ground tissue, so that
the stele appears tubular from the beginning. Botrychium virginianum undoubtedly
represents the most specialized type of the Ophioglossace, and the development
of the cambium with a permanent secondary thickening of the wood is an evidence
of a higher degree of specialization in the vascular system than is found in any other
living Pteridophyte. While a very slight indication of this secondary thickening
has been found in Ophioglossum, ‘and I have also noted some slight traces of it in
Helminthostachys, there is never developed in these the genuine cambium ring, such
as we find in Botrychium virginianum. In the development of the spiral protoxylem
elements Helminthostachys differs from the other Ophioglossacew and suggests the
true ferns. In the early development of its vascular system there rare strong sugges-
tions of some of the Marattiacez, especially Kaulfussia and Danaea. The develop-
ment of concentric bundles in the petiole in Helminthostachys and Botrychium
also suggests the Marattiacez.

Assuming that the collateral bundle, which is typical of the stem in all of the
Ophioglossacez and occurs also throughout in Ophioglossum, is primary, the con-

THE YOUNG SPOROPHYTE 83

centric bundles as they occur in the petiole of Helmunthostachys and Botrychium
must be considered as secondary. The monarch root of Ophioglossum moluc-
canum and the other members of the section Euophioglossum is to be considered
as a relic of the primary condition where the single axial stele, as in the young spo-
rophyte of O. moluccanum, had the single strand of practically uniform structure,
extending through the leaf and root. The development of diarch roots, such as
those of O. pendulum and Botrychtum, is probably also secondary and perhaps
associated with the early development of the second leaf in these forms. “The diarch
root appears again in the young sporophyte of the Marattiacee and is permanent in
most of the leptosporangiate ferns. The roots of the larger species of Botrychium
and especially those of Helminthostachys, with their increased number of xylems,
are undoubtedly secondary developments, perhaps associated with the large size of
the roots; and we again find this same type developing in the Marattiacea. In
regard to this point, Helminthostachys is the most aberrant of the Ophioglossacee
and approaches nearest to the Marattiacez.

The leaf in the smaller species of Ophioglossum is probably a very primitive
structure and the closed stipular sheath—which is not exclusively foliar in origin,
but at first owes part of its tissue to that of the cortex of the root, from which the
sporophyte arises—is probably an older structure than the strictly foliar, stipular
sheaths in Botrychium and Helminthostachys. Vhe simpler types of Botrychium,
like B. simplex and B. lunaria, show a transitional condition between the closed
sheath of Ophioglossum and the open sheath of B. virginianum, which may really
be spoken of as composed of two stipules, in this respect recalling the Marattiacee.
Helminthostachys, in the development of the stipular sheath, agrees exactly with
the simpler types of Botrychium. In these forms the sheath is face -shaped, open-
ing by a transverse slit in front and below, and the upper portion of the sheath is
broken through when the inclosed leaf emerges, so that the two apparent stipules
in He Frainthostach ys are really secondary, caused by a tearing of this hood-shaped
sheath, and are not proper stipules as they are in Botrychium virginianum.

The simpler and probably more primitive species of Botr ychium, like B.
simplex and B. lunaria, are obviously intermediate between Ophioglossum and
the larger and more specialized species of Botrychium. ‘This is shown in the form
and venation of the leaves, as well as in the character of their tissues. Instead of the
pinnate venation found in the leaves of B. wirginianum, these more primitive species
show no midrib in the leaf, but the veins all radiate from the veins of the leaflet,
dividing dichotomously, so that they are arranged in a fan-like fashion. Were the
ends of the veins connected there would result a reticulate venation, exactly like that
of Ophioglossum. ‘These leaves, moreover, are fleshy in consistence and have
stomata upon both sides, while in Botrychium virginianum and in Helminthostachys ys
the stomata are restricted to the lower surface of the leaf. In all of these particulars
Ophtioglossum and the simpler species of Botr ychium are evidently more primitive
than the other genera.

In Botrychium virgintanum, as we have seen, the cotyledon is extraordinarily
developed, more so than that of any other Pteridophyte. The contrast between
this highly developed cotyledon and the very rudimentary one in Botrychium lunarta,
where the young sporophyte passes several years under ground before the first green
leaf emerges, is very striking. It is, however, to be Aecirned that the rudimentary
condition of the leaves in Ophioglossum vulgatum and Botr ye hium lunaria is a
secondary condition, connected with their long life under eround.

Helminthostachys, on the whole, approaches more nearly to B. lunaria in its
early stages of development than it does to B. virgintanum. This is shown in the

S4 THE OPHIOGLOSSALES

rudimentary condition of the cotyledon and in the venation of the first foliage leaf,
which, although it has a ternate lamina, is quite rudimentary. We have already
referred, however, to the rudimentary leaves of B. lunarta, which also sometimes
develop a very small ternate lamina. ‘The venation of the first leaf in [1elminthos-
tachys also approaches the cyclopterid type found in the leaves of B. lunaria. The
structure of the stele in the young stem also, after attaining the tubular form, is
more like that of B. /unarra than like that of B. virgintanum.

On comparing the early stages of development of the Ophioglossacex and
Marattiacee we shall find that they have a good many points in common, which
will be discussed more at length after we have described the structures of the latter.
Ophtoglossum, as to the formation of the cotyledon, is very much like Kaulfussia,
while Helminthostachys is more suggestive of Danaea. “The stipular structures of
the two families are ‘unquestionably homologous and the entire conical stipular
sheath, found in the lower members of the Ophioglossacez, 1 is probably an older
type than the free stipules found in Botrychium virgintanum and the Marattiacex.

In both the Ophioglossacee and Marattiacee the young sporophyte at first is
made up almost entirely of leaf and root, and the whole vascular system is composed
of the leaf traces with no proper cauline vascular tissues, so that one might almost
say that the stem is made up entirely of the bases of the leaves, the dominance
of the leaf being the most noteworthy feature in the morphology of these plants.
On the whole, probably Helminthostachys most nearly resembles the Marattiacex.
This is true both of the character of the venation of the leaves, the structure of the
root bundles, and the development of tannin cells in the young sporophyte. These
tannin cells seem to be quite absent from the tissues of both Ophioglossum and
Botrychtum.

THE ADULT SPOROPHYTE 85

IV. THE ADULT SPOROPHYTE.

The essential characteristics of the sporophyte are established while it is still
quite small and the subsequent differences are mainly an increase in the size of the
parts and finally the development of the spore-bearing structures which constitute
the peculiar spike or sporangiophore so characteristic of these plants. As the
structure of the tissues has been repeatedly studied and described, no attempt will
be made here to take up a detailed study of these.

The Ophioglossacee in general, except for the rather elaborate vascular bundles
of the stem, especially in Botrychium, are marked by great simplicity in the structure
of the tissues. The surface is usually smooth except in the younger plants, where
there may be a development of scales and hairs, presumably for the protection
of the young tissues of the stem apex. The hard hypodermal tissues and bands
of sclerenchyma, so common in the leaves and stems of many ferns and developed
to a less degree 1 in the Marattiacez, are practically entirely absent from the Ophio-
glossacez.

Except for the vascular system of the stem the bundles are usually less developed
than is common in the more highly differentiated ferns, this being especially the case
in Ophioglossum, where the very delicate bundles forming the veins of the leaf run
through the spongy green tissue of the leaf without causing any projecting veins at
the surface. This condition is true also in the simpler types of Botrychiumand in
the young leaves of Helminthostachys. Vhe great bulk of the ground tissue in leaf,
root, and stem is parenchyma. The development of periderm i in the outer tissues
of the stem is probably always associated with the leaf bases and serves, as we have
seen, both to separate the dead leaf bases and to protect the scar thus left after the
leaf has fallen away.

The roots are characterized by the complete absence of root hairs. The outer-
most layer of cells often has the w alls much thickened and they may show the reac-
tion of cork. The bulk of the cortex of the root, however, is composed | of unmodified
parenchyma. The vascular cylinder in the root remains monarch in the section
Euophioglossum, but is diarch in the smaller roots of Ophioderma and in the smaller
species of Botry¢ chium, and ranges to hexarch in the larger roots of Helminthostachys.
‘The roots, especially in the larger species, are thick and fleshy and as a rule branch
sparingly and somewhat irregularly. In the section Euophioglossum no lateral
roots are formed and branching i is rare. When it does take place it is the result of a

true dichotomy of the apex. The root, as in the youngest stages in the plant, grows
almost always from a single tetrahedral apical cell, which is much alike in all the
genera.

The most characteristic feature of the Ophioglossacez is the peculiar sporangial
spike referred to. There is a certain correlation in the degree of development of this
spike and the sterile leaf segment with which it is associated. The fertile leaves
may arise very early in the history of the sporophyte. Bruchmann states that the
first leaf to appear above ground in Botrychium lunaria is already a fertile one and
in Ophioglossumv alcatel the second green leaf to be developed usually bears spores.
This early dev elopment of the fertile leaf is probably an indication of the primitive
nature of these plants, as we must assume that the ancestral form must have at once
developed a sporangial structure on the first leaf, or what corresponded to that in
the embryo. In Botrychium lunaria Bruchmann figures young spore- -bearing plants
which are still connected with the prothallium, and Jeffrey states that in B. virgini-
anum he once found a fruiting plant with which the -prothallium was still connected.

86

THE

THE OPHIOGLOSSALES

SPOROPHYTE OF OPHIOGLOSSUM.

Of the three existing genera of the Ophioglossacex, the genus Ophioglossum
is much the largest and most widespread. The number of species, however, is very
imperfectly understood, as there is great confusion in the nomenclature, owing to

Fic. 55-

Two specimens of Ophioglossum moluc-

canum (Schlecht), slightly reduced.

The larger one is the typical 0.
moluccanum; the smaller one is

probably a second species.

the inadequate study of the tropical species, of which
the number is undoubtedly much greater than has
generally been supposed. The smaller terrestrial species
look very much alike and it is evident that collectors have
often failed to discriminate among them. My attention
was especially called to this while I was collecting ma-
terial of Ophioglossum in Java, where there is evidently
a considerable number of species. Raciborski (Raci-
borski 1), who has described the Pteridophytes of this
region, mentions only a single species as occurring in the
neighborhood of Buitenzorg, where most of my collect-
ing was done. But in that immediate neighborhood |
collected at least three very distinct species, and two
were collected at Tjibodas, some 4,000 feet above Buit-
enzorg. Raciborski, however, mentions only a single
species as occurring at Tjibodas. There is no doubt
that a critical study of these plants from other regions
where they abound will greatly increase the number of
species to ‘be recorded.

The great majority of the species of Ophioglossum
belong to the subgenus Euophioglossum, which should
probably be separated completely from the very differ-
ent forms which comprise the other subgenera. The
species of Euophioglossum are all small or moderate-
sized plants with undivided leaves which are generally
lanceolate or broadly oval in outline and have the
sporangial spike borne on a very long stalk attached to
the sterile part of the leaf near ‘the base of the lamina.
These plants are always terrestrial, the leaves growing
from an upright rhizome, which is sometimes a good
deal enlarged, sometimes more slender in form. From
the rhizome there extend numerous roots which are
sometimes developed one for each leaf, but this is by
no means always the case. The sporophyte of Euophio-
glossum seldom exceeds a height of 30 to 40 centime-
ters and some of them are very much smaller (fig. 55,
also plate 3).

Except for their larger size the later leaves do not
differ essentially from the primary leaf of the young
sporophyte. The venation is always reticulate, usually

without any definite midrib, although sometimes there is a central vein which is
slightly stronger than the others. In many species, e. g., O. moluccanum, O. vulga-
tum, small branches ending blindly are found within the large meshes. In other
species, e. g., O. lusitanicum, there are no free veins within the areoles.

In many of the species but one leaf is formed each year, but in others, especially
many of the tropical species, there may be as many as four or five formed in a

THE ADULT SPOROPHYTE 87

single season. In O. vulgatum the development of the leaf is very slow, the leaf
remaining three years inclosed in the bud and emerging in the fourth season. So
far as I know, no study has been made of the development of the leaves in those
species of the temperate climates where more than one leaf is developed in the season,
and it remains to be seen whether the leaves which unfold in the same season are
of the same age or not. In the rapidly growing tropical species it is exceedingly
unlikely that more than a few months are necessary for the complete development
of the leaf, which unfolds as soon as it is mature, but no data are available on this
subject.

While the spike in Euophioglossum is usually inserted at the base of the sterile
lamina it may be attached much further down. This is especially noticeable in the
small species O. bergianum, from South America (see Bower 9, page 435). In O.
bergianum the leaves do not show a clear separation into lamina and petiole and the
spike is inserted close to the base of the linear leaf, so that it appears to be an en-
tirely distinct structure.

In nearly all of the species of Euophioglossum the later roots, like the primary
ones, are monarch, but in O. bergianum they are diarch. In most cases at least,
as Holle (Holle 1) showed, only one root is formed for each leaf. This seems to be
the case in O. moluccanum, which was investigated with some care.

Ophioglossum pendulum (plate 4, B) is the best-known representative of Ophio-
derma, the second section of the genus. This differs a good deal in its general char-
acters from the small terrestrial species of Euophioglossum. It is not uncommon
throughout the eastern tropics, where it grows as an epiphyte upon the trunks and
branches of various trees. The rough stems of certain tree ferns and some palm-
like species of Phanix form a favorite habitat for this fern in certain regions and,
as we have pointed out in the study of the gametophyte, it is frequently found rooting
in the masses of humus between the old leaf bases of some epiphytic ferns like
Asplenium nidus. ‘The stem, instead of being upright, is markedly dorsiventral,
but is short, with the leaves crowded together near the end and all growing upon
the dorsal side of the rhizome, as they do in Helminthostachys (fig. 63). The leaves
are very much elongated and the mbbon-like lamina merges very gradually into the
extremely stout petiole. ‘These leaves in large specimens may reach a length of
1.5 meters, or even more, and the long, strap-shaped leaves hanging down from the
boughs of the trees present a very characteristic appearance. In larger specimens
it is not uncommon to find the lamina dividing dichotomously (see plate 4, B) and
it is said that sometimes this dichotomy may extend to the petiole, in which case
each segment of the leaf bears a separate spike.

The venation of the leaf is reticulate, the veins inclosing long, narrow meshes
with no free veins, and the venation thus resembles the type represented in Euophio-
glossum by Ophioglossum lusitanicum. ‘The larger plants always have several
leaves which are expanded at the same time and growth goes on uninterruptedly,
The leaves are crowded together and there is no evident internode between them.
but it is clearly seen that they are arranged in two rows on the flanks of the short
rhizome (fig. 63, 4). The remains of the stipular sheaths surround the bases of
the leaves and these sometimes present the appearance of two small stipule-like
organs. As in Euophioglossum, adventitious buds are frequently formed upon the
roots. As a rule they are not terminal, but lateral structures and probably do not
differ essentially in their development from those of O. moluccanum.

The rhizome is more or less buried in the humus and the roots ramify through
this. Even in the very young plant the roots are branched and this branching
becomes very marked in the larger sporophyte. There seems to be some difference

88 THE OPHIOGLOSSALES

in the number of roots, but in most cases two were found connected with each leaf,
instead of one as | stated in my earlier description of the plant (Campbell 4). The
roots are very stout, sometimes attaining a diameter of over 3 millimeters. “The smaller
roots are diarch, but in the large roots there may be three, four, or even five xylems.

Ophioglossum pendulum is much the largest member of the Ophioglossacea
and the sporangial spike as well as the individual sporangia far exceeds in size those
of any other species (plate 4, B, 3-6). The spike is attached by a short peduncle and
hangs down from the pendent lamina. In large specimens the spike may reach a
length of 20 centimeters or more with a breadth of about a centimeter. Above the
insertion of the spike the leaf is thin, but the slender peduncle is continued downward
into a thick, flattened midrib which merges gradually into the petiole, so that the
spike has very much the appearance of being a terminal structure with the sterile
lamina adherent to it.

The young leaves in O. pendulum emerge while they are still very young and
the sporangial spike is in an extremely rudimentary condition ‘The general devel-
opment of the leaf is therefore very easy to follow in this species, as these young
leaves are entirely free.

The second species of the section Ophioderma is the rare O. intermedium
(fig. 69; plate 4, A). This for a long time was known only from one locality in
Borneo, but has lately been collected at other points in the Malayan region. The
specimens figured were collected by the writer near Buitenzorg in Java. In the
account of the Ophioglossacez given in Engler and Prantl’s “‘ Naturliche Pflanzen-
familien” (Bitter 2) it is suggested that O. :ntermedium is only a terrestrial form
of O. pendulum; but there is no doubt at all that itis a very distinct species. The
plants described here were growing in masses of humus at the base of old clumps of
bamboo. The stem is usually very short, forming a small tuberous body, from which,
in most cases, only a single leaf was growing, although two were sometimes found.
A careful examination of this short rhizome showed that, like Ophioglossum pendu-
Jum, it is dorsiventral. The roots were short and in all cases observed were without
branches. In one of the specimens a bud very similar indeed to the corresponding
buds in O. pendulum was found growing from one of the roots. Ophioglossum
intermedium differs from O. pendulum in being rigidly upright. The peduncle is
longer and the lamina of the leaf much smaller and more clearly differentiated from
the petiole. As in O. pendulum, however, the petiole is prolonged into the peduncle
of the spike with the same midrib-like thickening, caused by the coherence of the
basal part of the peduncle with the lamina.

This plant is exceedingly variable. In the larger specimens, except for the much
shorter lamina, the plant a good deal resembles small specimens of O. pendulum.
In others, however, the lamina is almost completely suppressed and this condition
closely approaches the third member of this section, Ophroglossum simplex (fig. 71).
This latter species is at present known only from one locality in Sumatra, and ts dis-
tinguished from all the other species of Ophioglossum by the practically complete
suppression of the sterile portion of the leaf (see Bower 8). The form of the rhizome
and the habit of the plant in O. simplex most nearly resemble O. intermedium, to
which it is probably not very distantly related. Whether or not we regard the
absence of the lamina of the leaf as a case of reduction, the fertile leaf in O. simplex
certainly very closely resembles what one would assume to have been the primitive
condition of the leaf in the ancestors of the Ophioglossacezx.

The third section, Cherroglossa, contains a single very peculiar species, O.
palmatum (plate 5). This occurs throughout tropical America, but does not seem
to be a common plant. It has been reported from Florida, where, however, it is

THE ADULT SPOROPHYTE 89

very rare. It has been collected in various parts of South America and in the West
Indies, and apparently the same species is known also from the Island of Bourbon
and from the Seychelles in the Indian Ocean. The specimens from which the
figures and descriptions given here were made were collected in the summer of 1908
in the Blue Mountains of Jamaica, and were found in one place only, growing upon
a rotten tree stump.

The rhizome in Ophioglossum palmatum is an almost globular tuber, which is
radially constructed and in this respect resembles that of Euophroglossum more
than that of Ophioderma. The leaf bases are covered with long brown hairs, which
give a characteristic appearance to the rhizome. The roots are numerous and more
slender than those of Ophioglossum pendulum. ‘hey are sparingly branched and
the branching may have the appearance of a true ‘dichotomy, but the material
available dae not allow of a critical investigation of this point. However, since
in Euophioglossum the branching of the roots is actually dichotomous, it is not
imposstble that the same may be true in Cherroglossa. The smaller roots, as in
O. pendulum, are diarch and, as in all of the other forms, a mycorrhiza is developed
in the cortical region.

In sections of one of the largest roots available the bundle was triarch. This
root was rather young and the tracheary tissue was only partially lignified. The
mycorrhiza was also less evident than in the smaller roots taken from a younger
plant. Two young plants were found which probably had arisen from buds upon
the roots of the older sporophyte. One of these is shown in figure 70, 4. It had
developed a single nearly lanceolate leaf very much like the early leaves of O.
pendulum. A single root had developed near the base of the leaf and this was joined
to the small globular rhizome. A second root could be seen above this, but whether
this second root belonged to the leaf or was part of the root upon which the bud had
arisen could not be ereemined

The older leaves may reach a length of 60 centimeters or more (plate 5). They
are more or less deeply palmately cleft into narrow segments, which give the leaf a
curious superficial resemblance to certain kelps, sn: as Laminaria digitata. The
base of the fan-shaped lamina is abruptly narrowed into a nearly cylindrical petiole,
ae equal in length to the lamina itself. The venation is rather of the type of

vulgatum, having numbers of free veins in addition to the elongated closed meshes.

In some of the smaller leaves (plate 5, 3) there is present a single small median
spike, which, like that of O. pendulum, has a short peduncle, but it 1s inserted below
the lamina, in this respect again being more like Euophioglossum. In the larger leaves
there are several sporangial spikes arranged in a series on either side of the petiole,
usually below the insertion of the (ana but sometimes some of them are inserted
above the junction of the lamina and the petiole. Bower (Bower 9, page 436) has
figured a series of specimens of this species showing the great variation in the number
and arrangement of the spikes. He emphasizes the fact that although these spikes
are apparently marginal, in reality they always arise from the dari side of the
leaf. He shows that in this species also there may be a branching of the individual
spikes similar to that which occurs in Ophioglossum pendulum alee frequently
in certain species of Euophioglossum.

THE ANATOMY OF EUOPHIOGLOSSUM

The stem apex of the adult plant has been repeatedly studied in the widespread
Ophioglossum vulgatum, but there is little information in regard to this pomt in
other species. From a somewhat careful examination of O. moluccanum it is evident
that this species agrees closely with O. vulgatum, and a study by one of my students,

90 THE OPHIOGLOSSALES

Mr. C. S. Morris, of this species and also of a broad-leaved form from Ceylon,
probably O. reticulatum, showed that the same characters prevail in the species he
examined as in O. vulgatum. It therefore seems likely that all species of Euophio-
glossum agree in the main in the structure of the stem apex and the development
of their tissues.

We have seen that in the young sporophyte the stem apex is completely inclosed
in a small cavity formed by the hood-like stipular sheath of the youngest leaf. This
condition, once established, is permanent (fig. 56) and there is no essential difference
in the appearance of the stem apex between a young plant in which two or three

Fic. 56.

Longitudinal sections of an older sporophyte of Ophioglossum moluccanum, showing arrangement of
vascular bundles; x, stem apex; sp, young sporophylls. D shows apical region more enlarged.

leaves have been developed and the full-grown sporophyte. The stem apex is of
limited extent, crowded in between the bases of the young leaves, and in O. moluc-
canum the single apical cell is of the same form as that which was found in the early
condition of the young bud; 1. e., in longitudinal section it is four-sided, with a
broad base and a narrower outer face. According to Holle (Holle 1), the apical
cell in O. vulgatum is pointed below; but Rostowzew (Rostowzew 2) in his figures
shows the same form as the apical cell in O. moluccanum. It is not at all impossible,
however, that both forms may occur, as in cross-sections the apical cell in O. mol-

uccanum may be either three-sided or four-sided (figs. 39 and 56, D). The apical

THE ADULT SPOROPHYTE 91

cell in O. moluccanum may therefore be described as a three-sided or four-sided pnsm
or a truncate pyramid.

As in the young plant, the stipular sheath of each new leaf is formed mainly
from the basal tissue of the leaf itself, but includes also tissue from the margin of
the stem apex. The sheath is open above by a narrow pore through which it
communicates with the space between it and the next stipular sheath. In O.
moluccanum, as in O. vulgatum, three leaves of different ages can generally be seen
inclosed in the bud and sometimes the first indication of the fourth young leaf can

B
Fic. 57.

Six of a series of cross-sections from a sporophyte of Ophioglossum moluccanum. sp, young sporophyll; x, stem apex.

also be distinguished (fig. 56,C,D). A cross-section of the youngest sheath shows
the pore as a minute opening, separated from the stem apex below by a very
narrow space.

A careful study of the older stem gives no reason for assuming that the tissues
of the very open reticulum forming the fibrovascular system of the ‘thizome is in any
part due to additions from the apical tissue of the stem. Whether longitudinal
or transverse sections are examined it is perfectly clear that the strands of this
reticulum are made up entirely of leaf traces which can be readily followed into the
young leaves or the tissue immediately below. The immediate apical region of the
stem, as in the younger sporophyte, is unmodified parenchyma which adds only to
the large central pith, if pith this can be called, as the separate bundles of which the
vascular reticulum is composed run free for long distances through the ground tissue

92 THE OPHIOGLOSSALES

of the stem, which is identical in appearance in the cortical and the central regions.
The bundle from each young leaf can be traced to a junction with a root stele and
from this point of junction it extends through the ground tissue of the stem, running
almost horizontally until it joins the trace from the next older leaf. In this way 1s
built up the open, large-meshed vascular cylinder. So far as could be determined
in O. moluccanum only one root was formed for each leaf. The tissues of the root
base are continued upward to connect with the young leaf and downward to join the
stele from an older one.

No endodermis can be detected in the bundles of the stem in O. vulgatum and
the same is true for O. moluccanum, but in O. bergianum, O. capense, and O. ellip-
ticum, according to Poirault (Poirault 2), both an inner and outer endodermis occur
in the older part of the rhizome; these however, disappear in the younger region
higher up.

A transverse section of the mature rhi-
zome (fig. 57) in Ophioglossum moluccanum
shows the widely separated sections of the
strands of the vascular cylinder as a circle
of small collateral bundles without any
endodermis, the mass of wood being in
immediate contact with the thin-walled
parenchyma of the ground tissue or sepa-
rated from it at most by a single row of
pericycle cells. In some of the smaller
species the leaf traces are relatively broader
and there is an approximation to the ring-
shaped section presented by the cylindrical
stele of Botrychium or Helminthostachys,
and sometimes the same appearance may be
approached in sections of the older rhizome
which happen to pass through a region
where there are numerous anastomoses of
the bundles forming the reticulum (fig. 57, £).

Except for the vascular bundles, the
tissue of the stem is made up almost ex-
clusively of simple parenchyma. The de-
velopment of periderm, which takes place
to a limited extent in the outer region, is
doubtless associated with the old leaf bases,
as it is in Botrychium.

The leaf structure of Euophroglossum is os ;
exceedingly simple. “The mesophyllis made Dxeaesl aie os mens d OMae
up of thin-walled green cells, practically uni-
form throughout; and through this spongy mass of mesophyll the delicate veins pass
without forming any projections at the surface. Both sides of the leaf are provided
with a simple epidermis, stomata being developed on both sides of the leaf. In
those species in which the leaf lies more or less horizontally, as it does, for example,
in O. reticulatum, the stomata are less numerous upon the upper surface.

The arrangement of the bundles in the petiole has been already studied in the
commoner European species, O. vulgatum and O. lusitanicum. In all of the species
belonging to the section Euophioglossum there is given off from the vascular system
of the rhizome a single leaf trace, which divides at the base of the leaf into two

THE ADULT SPOROPHYTE 93

strands. Each of these strands may divide, or only one of them (hg. 60). In some
of the smaller species there are only three bundles in the petiole, and in these forms
there are no anastomoses of the bundles above the base. In the larger species these
branches divide further and the number of bundles in the section is greater. Thus,
each of the two ventral bundles may divide again in the upper region of the petiole
so that a cross-section at this point would show five bundles, a large dorsal one
and two pairs of smaller ventral ones. A similar condition of things is found in the

Fic. 59.

A. Vascular bundle from an adult rhizome of Ophioglossum moluccanum. 150.
B. Section of an adult root showing monarch vascular cylinder. 35. The shaded zone
is occupied by the mycorrhiza.

small species, O. californicum. As sections are examined below the junction of the
lamina and the petiole, it can be seen that further forking of the bundles has taken
place preliminary to their entering the lamina itself. Some of the species have the
tissues of the petiole quite compact, others show a greater or less development of
lacunz or air-spaces in the petiole.

THE ROOT IN EUOPHIOGLOSSUM.

The early roots in O. moluccanum grow from a large tetrahedral apical cell
showing a fairly regular segmentation, much like that of the typical ferns; but the
root cap is not so well developed nor does it show as definite a stratification. In the

A | Cc fe)
F ]
E
G H I

Fic. 60.

Nine of a series of sections of a young sporophyll of Ophioglossum moluccanum. sp, the sporangiophore.

early roots the whole of the root cap seems to be derived from the outer segments
of the apical cell. In the later and larger roots there seems to be somewhat less
regularity in the segmentation and no sections were found which showed the apical

94 THE OPHIOGLOSSALES

cell and its segmentation as clearly as in the younger roots; however, only a small
number of these later roots were sectioned and it may be that they were not all
quite normal.

A section of an adult root is shown in fig. 59, B. ‘The cortical region is made up
of simple parenchyma and the mycorrhizal zone is very conspicuous. The endo-
dermis is not very clearly defined, less so than in the earlier roots, and its limits are

E

Fic. 61.

Five sections of a full-grown sporophyll of Ophioglossum moluccanum. E, section of peduncle of spike; /, lacuna’.

not easily determined. The cortical cells inside the mycorrhizal zone are densely
filled with starch. More than half of the section of the bundle is occupied by the
large solid mass of wood. This is separated from the endodermis by a single layer
of pericycle cells. The single mass of phloem lying next the wood is not much more
than half as large.

ANATOMY OF OPHIODERMA.

Owing to the dorsiventral position of the rhizome and to the more rapid de-
velopment of the leaves, the section of the stem apex in Ophioglossum pendulum
differs a good deal from a similar section of Euophioglossum (fig. 64). The base of
the leaf is bent sharply upward, this being the case also in the very young leaf which
is inclosed within the bud. The leaves break through
the inclosing sheath in a very rudimentary condition,
although of such size that a section through the base
of the youngest visible leaf shows usually but a single
younger leaf inside the sheath, instead of the three or
four that are seen in a similar section of the bud in
Euophioglossum. Within the sheath at the base of the
youngest visible leaf there is found a cavity in which is
the growing point of the stem and the youngest leaf.
The apex of the stem forms a strongly inclined, nearly f
plane surface and, as in Euophioglossum, the growth is Fic. 62.
from a single apical cell which, so far as could be deter- Apex of root of Ophoglossum moluc-
mined, has the form of a three-sided pyramid, whose PRN AS la tan
lateral faces are more or less strongly convex and whose apex may be truncate.
From the few cases observed it is not possible to say definitely whether basal seg-
ments are regularly cut off as well as the lateral ones. The segments cut off from
the lateral faces are large and the divisions irregular.

Owing to the large size of the sporophyte there are practical difficulties con-
nected with the study of the vascular system of the rhizome from a series of micro-
tome sections. ‘The numerous bundles in the leaf base do not unite into a single

THE ADULT SPOROPHYTE 95

leaf trace, but pass downward through the cortex separately, and even if it were
possible to make a satisfactory series of the sections of the large rhizome the task of
following the course of the very numerous individual bundles would be a difficult
one. From free-hand sections of the large base of the leaf, however, one can see
without difficulty the general plan of the vascular skeleton. The stout petiole is
slightly contracted at its base, but a section presents very much the same appear-
ance as one made higher up.

In specimens that have been preserved in alcohol so as to become decolored,
the tissues of the thick leaf base are sufficiently transparent to show quite clearly
the course of the bundles even without sectioning, by simply slitting the petiole
through the middle. The bundles are seen to anastomose freely at the extreme base
of the leaf, very much as they do in the lamina. If such a section 1s examined where
the leaf base joins the rhizome (fig. 63, D) the circle of bundles can be seen to become

Fic. 63.—O phioglessum pendulum L.
3 phrog p

A. Stem showing dorsiventral form and branched roots. /, bases of leaves.

B. Buds attached to a root fragment. The older bud, b*, has developed a young sporophyll, sp, and two secondary roots.
C. Base of a large leaf, showing arrangement of vascular bundles.

D. Section of same.

smaller as the bundles enter the cortex, but the bundles remain for the most part
quite separate, although there may be an occasional anastomosing of these, as occurs
in the petiole itself. This group of bundles composing the leaf trace—if such it
can be called—forms a circle about the opening in the vascular cylinder of the stem
where it joins the latter. A section of the vascular cylinder within the rhizome itself
presents the appearance of a nearly complete ring, which is probably formed by fus-
ing of the bundles derived from the leaf bases. The much greater development of
woody tissue in the stem of O. pendulum as compared with that of Euophioglossum
is doubtless due to the very much larger size of the leaves and the correspondingly
greater number of vascular bundles contributed by them to the woody cylinder of
the rhizome.

The very young leaf, such as is shown in fig. 63, B, has a thick, fleshy leaf base,
terminating in a very small and pointed lamina strongly bent over as it Is, e. g.,
in the young leaf of Botrychium virginianum. This differs from the species of
Euophioglossum, in which the leaf is straight in the bud. Under the arching hood
formed by this folded-over lamina is the young spike, almost equal in length at this
time to the lamina itself. A somewhat older stage is shown in fig. 82, B. The
leaf has now become somewhat flattened, but as yet there is no sharp distinction
between the lamina and the petiole. In this early stage of development the inter-
pretation of the spike as a terminal structure seems very plausible. An interesting

96 THE OPHIOGLOSSALES

case is shown in fig. 82, £, where the lamina is almost entirely suppressed and the
terminal character of the spike is very evident.

As the leaf develops, there is a very great increase in size in the lamina, which,
as we have seen, may reach a great length. The anatomical structure of the leaf

sp
B
Fic. 64.— 0 phioglossum pendulum.
A. Section of stem apex. 3. D. The stem apex, more enlarged.
B. Young sporophyll. sp, sporangiophore. 35. E. Very young sporophyll. sp, sporangiophore. go.
C. Stem apex, x, and youngest leaf, /. F. Cross-section of young sporangiophore.

closely resembles that of Euophioglossum, but the stomata are much larger and
around the stoma is a concentrically arranged series of cells, indicating that probably
the formation of the mother cell of the stoma is preceded by a series of preliminary

Fic. 66.

A. Section of petiole of a sporophyll of O. pendulum.

B. Section near base of lamina. sp, base of spike.

Fic. 65.—Vascular bundle from petiole of O phioglos- C-E. Sections of peduncle of spike. C and D are from the
sum pendulum. same leaf; E from a latger one.

divisions in the epidermal cell. The tissues in the petiole are very like those in the
lamina of the leaf except that they are somewhat more compact. The walls of the
ground tissue in this region are very deeply pitted.

The structure of the vascular bundle of the petiole (fig. 65), is much like that in
Euophioglossum, except that there isa rather greater development of tissue upon the

THE ADULT SPOROPHYTE 97

inner side of the wood, so that there is a slight suggestion, at least, of a concentric
structure of the bundle, such as 1s found in the petioles of Botrychium. The xylem is
composed entirely of tracheids with reticulate markings. The rest of the bundle is
made up of sieve tubes, mingled irregularly with smaller, thin-walled elements. It

\ could not be certainly deter-
mined whether any sieve tubes
were developed on the inner
side of the wood.

The number of bundles in
the petiole, especially in large
specimens, is much greater
than in any of the species of
Euophioglossum. In a spe-
cimen of medium size (fig. 66)
eighteen bundles could be
seen, of which probably seven
or eight are destined to sup-
ply the spike. In the fertile
leaves these form a complete
circle, but in sterile leaves
. there are no bundles on the
adaxial side of the section. In the free portion of the peduncle, which is relatively
slender, the number of bundles is much less than in the broad basal portion. In
the smaller specimen figured there were but three bundles in the middle part of the
peduncle. The complete absence of the adaxial strands in the petiole of the sterile
leaf, even at its base, is a strong confirmation of the view suggested by both the older
leaf and the younger stages, that the peduncle is really an independent structure
whose bundles are joined directly to the rhizome.

Fic. 67.

A, longitudinal; B, transverse section of the root apex of Ophioglossum pendulum

Fic. 68.

A. Diarch root-bundle of Ophioglossum pendulum.
B. Tetrarch root of the same. X20. Dotted area is mycorrhizal zone.

O. intermedium (fig. 69) closely resembles O. pendulum in its anatomy, like the
latter developing stomata upon both sides of the leaf, and these stomata are very
large and show accessory cells similar to those found about the stomata of O.
pendulum. Except for the difference in size, the arrangement of the vascular bundles
in the peduncle and their structure is closely similar to.that in O. pendulum.

7

98

THE OPHIOGLOSSALES

The anatomy of O. simplex, so far as it has been investigated (see Bower 8)
corresponds closely with that of the other species of the section Ophioderma.
The roots of O. pendulum also show the tetrahedral apical cell (fig. 67), but the

Pa

Fic. 69.

Five specimens of O. intermedium Hk., slightly reduced.

C and D have a very much reduced lamina.

divisions are much less regular than in
O. moluccanum and probably the other
species of the Euophioglossum. The
segments divide slowly and increase a
good deal in size before the first divi-
sions take place, so that the youngest
segments may equal the apical cell in
size, and there is thus a certain resem-
blance to the apical meristem in the
root of the Marattiacex. It is prob-
able that, as in the Marattiacez, the
lateral segments of the apical cell also
contribute to the root cap, which ts
rather better developed than it is in
QO: moluccanum.

There is a good deal of difference
in the structure of the root bundle
(fg.68). This is diarch in the primary
root, as we have seen, and also in the
smaller ones of older sporophytes; but
in the larger roots, which may reach
a diameter of over 3 millimeters, it is
triarch; tetrarch bundles are also com-
mon, and in one very large root which
I examined the bundle was pentarch,

but one of the xylem rays was shorter than the others, the xylem forming a solid
central mass having the form of an irregular five-pointed star.

Fic. 70.

A. Small plant of Ophioglossum palmatum L., growing as a bud upon a root fragment

B. Hairs from base of leaf.

X35.

C. Section of petiole of a large leaf.

X7-5-

THE ADULT SPOROPHYTE 99
ANATOMY OF CHEIROGLOSSA.

Material was lacking for a study of the anatomy of the rhizome in O. palmatum
(fig. 70), but the structure of the petiole is very much like that of O. pendulum and
probably the same relation of the leaf bundles to the bundles of the rhizome obtain
as in O. pendulum. ‘he difference in the venation has already been pointed out
and the leaves differ also from those of O. pendulum in the fact that stomata are
developed only upon the lower side. A feature of this species ts the presence at the
base of the leaves of very conspicuous multicellular branching hairs, quite different
from those found in any other species of Ophioglossum (hg. 70, C). I find that the
cells are much more elongated in my specimens than those figured in the account
of the Ophioglossacez given in the Naturliche PAu aeeniemlen

THE SPOROPHYTE OF BOTRYCHIUM.

There is much the same uncertainty as to the number of species of Botrychium
that there is in Ophioglossum. Some of the species are exceedingly variable and
their limits are difficult to determine. Bitter, in his account of the “Ophioglossaceae
in Engler and Prantl’s ““ Naturliche Pflanzenfamilien,” states that there are sixteen
species. Underwood (Underwood 1) says “about thirty,” of which fifteen occur in
the United States. Christensen in his Index Filicum recognizes thirty-four species.

Many of the species are very widespread, being most abundant in the North
Temperate Zone. According to Christ (Christ 1), B. lunara is not only widespread
throughout the colder parts “of the Northern Hemisphere, but occurs again in the
corresponding regions of the Southern Hemisphere, having been reported from Pat-
agonia, southern Australia, Tasmania, and New Zealand. A few species occur in
the mountain regions of the tropics; thus B. /anuginosum is not uncommon in the
highlands of Ceylon, where I collected it at an altitude of about 7,000 feet.

The simplest member of the genus is Botrychium simplex, a very variable
species occurring at various places in North America, northern Asia, and Europe.
Its smaller forms closely resemble a small Ophioglossum (fig. 72, 4, B), except that
the sporangia are more distinct. From this primitive type, obviously not very
remote from Ophioglossum, there is an interesting series of forms leading up to the
large species like B. virginianum and B. silaifolium. ‘This latter species, which
grows in the mountains of western North America, is perhaps the largest of the
genus (plate 7). The plant is sometimes 2 feet high, the leaf nearly a foot in width,
and the very large panicle of sporangia 6 inches or more in length.

In the evolution of the leaf in Botrychium, the sporangiophore shows a devel-
opment parallel with that of the sterile leaf. In the forms of B. simplex, having
an entirely undivided sterile lamina, the sporangiophore has the form of a simple
spike with a single row of large sessile sporangia on either side (fig. 72, 4) and very
closely resembles a small Ophioglossum. As the sterile leaf segment becomes more
ae more dissected, aoe Isa SOUESPONL SE branching of the SOR SOD eR REE:

* Professor Bower, at the last meeting of the British Association for the Advancement of Science, read a paper on the ares
of Ophioglossum palmatum. This has not yet been published, but Professor Bower has kindly furnished me with an abstract of
his paper from which the following extract is quoted.

“Tt was thought probable that O. palmatum (the only species of section Cheiroglossa) would share with the species
named (f.., the species of O phisderma) the character of a divided (leaf) trace, and material collected in Jamaica has shown
that it does. The axis is much distended by parenchymatous storage tissue in pith and cortex, and as a consequence the
meshes of the stele are transversely widened. From their margins right and left, but not quite simultaneously, arise two
strap-shaped strands, which are thus widely apart in their origin. After subdivision into numerous smaller strands, these
range themselves into two fan-like semicircles, which spread till their margins meet, forming the circle of strands of the
petiole. A remarkable feature of the stock is the intrusion of roots into the bulky pith; this is especially obvious
towards the base, where they pass out as thick mycorrhizic roots.”

This behavior of the roots recalls that of the Marattiacee.

100 THE OPHIOGLOSSALES

in the large forms of B. virgintanum and B. silaifolium, forms a large panicle 15
centimeters or more in length and bears many hundred sporangia. ‘Two types of
leaf division may be noted, a pinnate form represented by B. /unaria and its allies,
which are sometimes separated as a special genus Eubotrychium, and a ternate
division which is found in all of the larger species. These larger species form a
second section, Phyllotrichium. A third genus, Osmundopteris, has been proposed to
include Botrychtum virginianum and its allies. In most of the species of Botrychium

Wy Ac

Fic. 71.
Ophioglossum simplex Fic. 72.—(A-D, after Luerssen.)
Ridley (after Bower). 3 : j
Thefertisles® has vib A, B. Botrychium simplex Hitchcock. C, B. ternatum Swz.
D, B. lunaria (L.) Swz. E, B. virginianum (L.) Swz.

sterile lamina.

—

THE ADULT SPOROPHYTE 101

the texture of the leaf is soft and fleshy, like that of Ophroglossum, but in B. virgini-
anum it is thin and membranaceous, like that of many true ferns. In B. lunaria
(fig. 72, D) the venation comes nearer to that of Ophioglossum than is the case in
the larger species. The fan-shaped leaflets have no midrib and the veins branch
dichotomously from the base of leaf, radiating from this point in the manner de-
scribed as ‘“‘cyclopterid.’”’ In the larger species the leaflets have a distinct midrib

Fic. 73.

A. Rhizome of a strong plant of Botrychium virginianum. 1. The base of the expanded leaf is cut away.
B. Section of the terminal bud. sf, stem apex. 1, 11, 11, the three youngest leaves. 2.66.
C. Section of petiole, enlarged.

D. Section of rhizome; p, pith; m, medullary rays; x, xylem; pA, phloem; c, cambium; sh, endodermis. X16.

Fic. 74.

A-G. A series of sections of the sporophyll of Botrychium lanuginosum Wall. C is reversed in
position. G, section of peduncle.
H. Section of the petiole of the cotyledon of B. virginianum. 1,1, lacune.

and the forking veins are attached to this laterally (fig. 72, £). The type of B.
lunarta is without question the more primitive, and were the ends of the veins united
so as to inclose areoles there would be exactly the same type of venation as is found
in Ophioglossum.

In Eubotrychium the anatomy of the leaf is almost exactly like that of Ophro-
glossum, stomata being developed upon both sides of the leaf, the mesophyll is
composed of absolutely similar cells throughout and the vascular bundles running

102 THE OPHIOGLOSSALES

through the mesophyll do not project at the surface as veins. In the section Phyllo-
trichium, where the sterile lamina is horizontal, stomata are developed only upon the
lower surface. In these forms the mesophyll is more compact upon the upper side,
but does not develop a distinct palisade layer. ‘The epidermal cells may be simply
elongated, e. g., B. lanuginosum, or they may be undulate, e. g., B. virgintanum.
The development of the stomata was examined in B. /anuginosum and the stoma
was found to arise directly from an unmodified epidermal cell. The section Eubo-
trychium shows a further approach to Ophioglossum in the character of its stipular
sheath, which, as we have seen, forms a hood-like appendage at the base of the leaf,
while in B. virginianum the stipular sheath is open in front, so that there are really
two stipules. Moreover, the leaf in the latter is sharply bent over in the bud in a
way to suggest somewhat the circinate vernation of the Marattiacew. For the most
part the surface of the plant is quite smooth, as in Ophioglossum, but the sheaths

Fic. 75.

. Stem apex of young sporophyte of Botrychium virgintanum. x, apical cell; /, youngest leaf. 200.
. Cross-section of stem apex.

Part of vascular cylinder of stem. p/, phloem; cam, cambium; xy, xylem; m, medullary ray.

- Some of the tracheids, more enlarged, showing bordered pits.

vor

enveloping the young leaves, as well as the very young leaves themselves, are often
hairy, and in a very few species, like B. /anuginosum, long and slender unicellular
hairs are sparsely scattered over the surface of the adult leaf. The stem, as we have
seen, is always an upright rhizome and usually unbranched, but adventitious buds
may be developed (see Bruchmann 2). These adventitious buds may develop into
lateral branches. In one specimen of B. Januginosum examined by me there were
two equal branches, presenting the appearance of a dichotomy, but a careful exam-
ination indicated that the original apex had been destroyed and that these two
branches were lateral shoots, which had probably arisen as adventitious buds. In
Eubotrychium the leaves are arranged spirally upon the rhizome, as they are in
Euophioglossum. This is also true of certain members of the section Phyllotrichium,
but others, e. g., B. ternatum, are arranged in two rows, thus suggesting the dorsi-
ventral arrangement found in Helminthostachys.

The structure of the adult stem does not differ, except in size, from that of the
younger plants already described. In Eubotrychium the cambium is absent and
apparently there is no secondary increase in diameter, but all of the larger species
of Phyllotrichium show a greater or less development of the cambium, which we have

THE ADULT SPOROPHYTE 103

noted in the bundle of B. virgintanum. The position of the sporangiophore is some-
what different in different species. In Eubotrychium it is attached, as a rule, close to
the junction of the sterile lamina and the petiole, very much as it is in Euophioglossum.
In B. ternatum and B. obliquum the long peduncle is inserted very much further
down, sometimes almost at the level of the ground, so that at first sight the spor-
angiophore seems to be quite independent of the sterile leaf. In B. wirginitanum

Fic. 76.

Tetrarch root of Botrychium virginianum en, endodermis; x, xylem; ph, phloem.

A. Apex of primary root of Botrychium virginianum. X200. C. Apex of large root, transverse section.
B. Apex of second root. 125. D. Diarch vascular bundle of the primary root.

and B. lanuginosum it is inserted close to the base of the sterile lamina or even
above its base, and in the latter species there may even be sometimes a second spo-
rangiophore developed on the fertile leaf above the insertion of the primary one.

Certain species show various monstrosities, this being particularly the case
with B.unaria. In such forms certain of the segments of the sterile lamina may bear
sporangia. A number of these curious forms are figured by Goebel (Goebel 2).

104 THE OPHIOGLOSSALES

In fig. 73, 4, is shown the terminal bud of a strong plant of B. virginianum.
The base of the oldest leaf is cut away so as to show the young leaf for the next
year, which is seen to be strongly bent over, and the young leaf segments are rolled
inward in a way that very strongly reminds one of the young leaves of the typical
ferns. The young leaf is covered with hairs. The roots are thick and fleshy, prob-
ably one corresponding to each leaf, although this is not always easy to determine.
They are much contracted at the point of insertion. The roots branch freely, the
branching being monopodial, thus resembling Ophioglossum pendulum. An exam-
ination of the section of the bud shown in fig. 73 shows that the young leaf, which
is to unfold the next year, is already well advanced and the formation of the young
sporangia has just begun. The sporangiophore is also evident upon the leaf for the
following year, and the leaf which is to unfold in the third year can be recognized,
but its parts are not yet differentiated.

While the roots branch freely in B. virginianum, this is much less marked in
B.lunaria. In large plants of B. lanuginosum which were examined somewhat
carefully it was found that the roots appeared to be quite unbranched, although
equaling those of B. virginianum in diameter and showing, like them, a similar
tetrarch structure of the vascular cylinder. A more careful examination showed,
however, a few very short branches on some of the roots, but these were rare. It
may be that the rudiments of these lateral roots are formed, but that they do not
develop, and in this respect there is a certain resemblance to the condition which
obtains in Helminthostachys.

The anatomy of the roots does not differ from that of the younger sporophyte
already described, except that in the larger specimens the roots are regularly tetrarch,
while in Eubotrychium they are permanently diarch.

The earlier roots, as in Ophioglossum, have a tetrahedral apical cell which shows
a more regular segmentation than is found in the later roots and in these earlier
roots, at least in B. virginianum, there seems little question that the tissue of the
root cap is derived entirely from the outer segments of the apical cell. In the larger
roots, taken from the older sporophyte, this regularity is not so marked and it is
probable, although this could not be determined absolutely, that the lateral seg-
ments of the apical cell may also contribute to the tissues of the root cap. The
regularity of the segmentation is still less marked in the later roots of B. obliquum.
A slight development of periderm may be seen in the older roots, but this does not
form a continuous layer, being developed only in irregular patches. The secondary
increase in diameter of the roots is apparently due almost entirely to simple enlarge-
ment of the cortical cells.

THE SPOROPHYTE OF HELMINTHOSTACHYS.

While Helminthostachys differs very much in habit from the other Ophio-
glossacez, it nevertheless shows that it is unmistakably related to them and especially
to Botrychium. The dorsiventral prostrate rhizome with the ample palmately
divided leaves give it a very individual aspect, but, as is shown from a study of the
early history of the sporophyte and the gametophyte, there is no question that it
should be associated with the Ophioglossacex. As yet but a single species is gener-
ally recognized, which grows throughout the Indo-Malayan region, extending from
the Himalayas through the Malay archipelago to northern Australia (plate 8).

The anatomical details of the adult plant have been very thoroughly investigated
by Farmer and Freeman (Farmer 2), and from a comparison of the structure of the
adult sporophyte with that of the younger stages it is clear that the essential

THE ADULT SPOROPHYTE 105

characters are established at a comparatively early period. The rhizome (fig. 79)
has the leaves arranged in two rows on the dorsal side, somewhat as in Ophioglossum
pendulum, but the leaves are less crowded and the internodes are evident, although
less marked than is often the case in the very young sporophyte. The youngest
leaves, still inclosed in the stipular sheath of the next older one, are conspicuous as
blunt projections, situated between the apex of the rhizome and the first expanded
leaf. As the leaf breaks through the stipular sheath of the next older one the
sheath is split into two stipule-like flaps, which much resemble superficially the
stipules of the Marattiacee. From near the base of the leaves on the flanks of the
rhizome and belonging to the ventral portion of the stem there arise the thick fleshy

Fic. 78.
A. Sporophyll of Helminthostachys, somewhat reduced. D. Four sections of the sporophyll Fig. 3 passes
B. Base of sporangiophore, about natural size. through the base of the spike, sp; 4, section of
C. Stoma. 200. peduncle of spike.

roots, which resemble those of the other Ophioglossacez. According to Prantl
(Prantl 1) and Farmer (Farmer 2), the roots bear no definite relation to the leaf,
and the number as a rule somewhat exceeds those of the leaves. “The roots branch
monopodially, as in the larger species of Botrychium, but Farmer states that the
lateral rudiments often prove abortive, or fall away at an early period, so that the
roots are apparently unbranched. ‘This behavior recalls the condition found in
Botrychium lanuginosum.

The leaves are very different in general aspect from those of the other Ophio-
glossacez, but are really not very different in their method of branching from the
ternate forms of Botrychium. There are still traces of the three primary divisions
of the first leaves which undergo subsequent divisions, so that the leaf has a palmate
form (plate 8, B). To a certain extent, however, these divisions are the result of

106 THE OPHIOGLOSSALES

unequal dichotomy, like that which results in the first divisions of the primary leaves.
In large plants the leaves may reach alength of 30 or 40centimeters. ‘The petiole is
nearly cylindrical at its base, but higher up becomes slightly winged at the margins,
these wings passing into the lamina. A section of the petiole taken a little way
below the insertion of the sterile lamina shows that the peduncle of the sporangio-
phore is recognizable for a long distance below the point at which it becomes free,
its adaxial surface projecting as a rounded ridge between the wings on the margin
of the petiole (fg. 78, D). In texture the leaves are frmer and more leathery than
in any of the other Ophioglossacee, and in this respect, as well as in their venation,
they closely resemble such Marattiaceee as Danea and Angiopterts.

The sporangiophore is tosome extent intermediate in character between that of
Ophioglossum and Botrychium. It is inserted near the junction of the lamina and
petiole, but, as already stated, can be traced for some distance below the point where
it joins the petiole. The fertile portion of the sporangiophore, which may reach a
length of nearly 10 centimeters, is composed of crowded, short branches, upon

Fic. 79.

A. Rhizome of Helminthostachys. sh, stipular sheath. X1.5.
B. Section of rhizome. The dark spots are tannin sacs.
C. Tannin sacs from the rhizome.

which are borne groups of nearly globular sporangia much like those of Botrychium.
The ends of the branches which bear the sporangia may be expanded into small leaf-
like organs which, under exceptional conditions, look much like small leaves, upon
which the individual sporangia are borne (see Bower 9, fig. 239). The stem in
Helminthostachys almost always remains unbranched, except that there may be
formed adventitious buds somewhat as in Botrychium. The origin of these buds,
however, has not been investigated. The rhizome is rather fleshy in texture and
may reach a diameter of about a centimeter. Usually but one leaf is fully developed
at a time, but it is not uncommon to find two leaves produced the same season.
Farmer’s description and figures of the structure of the terminal bud show that it is
essentially the same as we have found it to be in the younger plant, and, as has
already been pointed out, it shows strong resemblances to the terminal bud in
Botrychium lunarta.

The stomata (fig. 78, C) are confined to the lower surface of the leaf and are
surrounded by a series of concentrically placed cells like those around the stoma in
Ophioglossum pendulum. They are much smaller in size, however, and in this

THE ADULT SPOROPHYTE 107

respect may better be compared to the stomata of Danaa, one of the Marattia-
cee, which shows a similar concentric arrangement of the accessory cells. A
cross-section of the leaf shows that the mesophyll is better differentiated than in
Botrychium. ‘There is a single compact layer of palisade cells below the epidermis,
and below these the mesophyll has very large intercellular spaces which communicate
with the stomata. In the anatomy of the leaf, therefore, as well as in its venation,
Helminthostachys more nearly resembles the Marattiacee than it does the other
Ophioglossacee. The section of the petiole is not unlike that of Ophioglossum
pendulum (figure 78, D). A section made near the base of the petiole is almost
circular in outline and there is a ring of separate bundles. On the adaxial side,
however, two other bundles are seen adie the outer circle. Farmer and Freeman
(Farmer 2) state that the number of bundles is about seven or eight, but the
larger specimens which I have examined show a greater number. If a section of
the petiole is examined higher up it no longer appears circular, but is slightly
lobed, these lobes corresponding to the bases of the three divisions of the sterile
lamina, and on the adaxial side may be seen a fourth lobe which marks the position
of the peduncle of the sporangiophore. In this upper region of the petiole the
bundles become more or less coalescent, but two adaxial bundles remain quite
distinct and are continued upward into the spike. The structure of the bundles is
concentric and the general appearance of the section is quite similar to that found
in the larger species of Botrychium.

The anatomy of the stem in the older sporophyte does not differ in any partic-
ular, except in the greater size of its parts, from that of the sporophytes already
described. They eel cylinder forms a hollow tube with narrow leaf gaps above,
but quite solid on its ventr al face. Farmer states that there is both an outer and an
inner endodermis and that wood is formed inside of the protoxylem, so that the
bundle is mesarch.

Reference has already been made to the invaginated canals communicating with
the stipular cavities and first described by Gwynne- Vaughn (Gwynne-V aughn I):
In connection with these he describes slight projections = tissue from the ecnes:
cylinder, which are surrounded by the Sadodennis These projections he thinks

may perhaps be the vestiges of buds which formed at the axils of the leaves and
never developed. W bese this explanation is the correct one or not there is no
means of determining. Farmer found in the older plants that the roots were prevail-
ingly hexarch, ranging from pentarch to heptarch, and that tetrarch roots were rare.

The Bedadenaes in the bundles of the later roots is much less distinct than it is
in the primary root, where it is very easily demonstrated. Within the endodermis
is a layer of pericycle cells, separating the endodermis from the radially arranged
masses of xylem and phloem. Farmer states that the apical cell of the root appears
triangular in section (presumably in longitudinal section), but that it is very often
destroy ed and as a result of the proliferation of the adjacent tissue an area of cells
results recalling the condition obtaining in the Marattiacee. He also remarks that
most of the roots that he examined showed this abnormal condition.

I made sections of a number of roots taken from young sporophytes where the
root tips appeared to be quite normal. The result was rather interesting. In the
early roots there was usually present a tetrahedral apical cell, very much like that
of Botrychium and showing a pretty regular segmentation (fig. 80, C). The seg-
ments cut off from the apical cell are large, and even in the early roots it 1s pretty
certain that the root cap owes its origin, in part at least, to the outer cells of the lateral
segments. Cross-sections of the apical cell show the same triangular form as longi-
tudinal sections and the divisions in the segments of the apical cell seem to be very

108 THE OPHIOGLOSSALES

much as they are in Botrychium. In one small root, however (fig. 80, D), the apex
was occupied by three cells which together formed a triangular group, but these
cells were of about equal size and it is not at all certain that the triangular cell x
was really the apical cell.

In longitudinal sections of the larger roots there is a close approximation of
the condition found in the Marattiacew. There is probably still a single apical cell,
as there is in the early roots of the Marattiacea, but this cell is somewhat truncate
below (hg. 53, B) and in a cross-section, taken from a tetrarch root, a single apical
cell was not clearly to be distinguished. The lateral segments are very large and

Y, (|
Nene r] CORN
aii
aan

Fic. 80.

A. Section of pentarch root of Helminthostachys. X20. C. Root of young sporophyte, with tetrahedral apical cell. 150.
B. Part of the vascular bundle. 150. D. Root of an older sporophyte, with truncate apical cell, x.

there are cut off from them cells which contribute to the root cap. In short, the

apical growth in the later roots of Helminthostachys is evidently more like that of
Danea, for example, than it is like Botrychium.

THE SPORANGIOPHORE OF THE OPHIOGLOSSALES.

In all of the Ophioglossacee the sporophyll, as we have seen, consists of two
parts, the fertile spike (or sporangiophore) and the sterile lamina. There is very
great diversity of opinion as to the real nature of the sporangiophore. The earlier
views were strongly influenced by the old theory that the sporangial parts were

THE ADULT SPOROPHYTE 109

secondary modifications of an originally sterile leaf. At present it is the belief of
most students of the ferns that the fertile structures of the sporophyll are older than
the sterile ones, and this has led to a quite different interpretation of the real nature
of the fertile segments.

Bower (Bower 9) has treated at length the different theories that have been
proposed to explain the nature of the fertile spike in the Ophioglossacee. We can
only refer briefly to some of the more important of these. Mettenius (Mettenius 1)
considered that the two parts of ce leaf were of equal value, but he gives no data
as to their origin. Later writers, e. g., Holle (Holle 1), Goebel (Goebel 1), and very
recently Chrysler (Chrysler 1), Sel the fertile spike to be the equivalent of the
fertile pinne of such a fern as Anermia. Holle and Chrysler think that the single
median spike is the equivalent of two united pinnae. Goebel thinks that the spike
represents a single pinna which has arisen in a median position instead of upon
the margin. Chrysler’s results are based mainly upon a study of the distribution of
the vascular bundles in Botrychium. His results, however, do not take into account
the early development of the sporangiophore and its relation to the primordium
of the very young fertile leaf.

Bower, who has made the most complete study of the development of the spore-
bearing parts in the Ophioglossacez that has yet been published, concluded in his
earlier work that the spike of Ophioglossum i is morphologically equivalent to the
single sporangium of Lycopodium. In this view he was supported by Strasburger
and Celakovsky (Celakovsky 1). More recently, however, he has modified his view
(Bower 9) and concludes that the sporangial spike is a distinct organ, for which he
suggests the name “‘sporangiophore.” ‘This later interpretation we believe to be
the correct one.

In Ophioglossum the sporangiophore develops a peduncle which is often very
much longer than the sterile ee of the leaf and forms much the most conspicuous
portion of the sporophyll (fig. 55). The fertile portion of the sporangiophore is a
flattened spike along whose margins the two rows of large sporangia are borne.
These project very little, the cavity 7 of the sporangium being ‘deeply sunk in the tissue
of the spike and covered by several layers of cells forming the outer wall of the spor-
angium. The number of the sporangia in a spike may be only six or seven in some
of the small forms of Euophioglossum, or it may be very large, as it is in the great
spikes of O. pendulum.

In O. pendulum and O. intermedium the spike is more flattened than it is in the
species of Euophioglossum and the central sterile portion is wider in proportion.
Stomata are almost entirely absent from the epidermis of the spike in O. pendulum,
although occasionally a few are found in the central region. In O. intermedium
they are more numerous than in O. pendulum, but much less abundant than in the
species of Euophioglossum. In the latter they may occur even upon the epidermis
of the wall of the sporangium. The most marked exception in the position of the
sporangiophore is seen in the section Cheiroglossa (plate 5). In this form there are
several sporangiophores developed upon the leaf. Although these are apparently mar-
ginal in position, it is claimed by Bower that they are really always developed upon
the adaxial surface of the leaf. Some of the smaller forms may show a single spike
which occupies a central position, very much like that of O. pendulum (plate 5, 3).

In some of the simpler forms of Botr ychium simplex the sporangiophore is very
much like that of a small Ophioglossum, except that the individual sporangia are
more distinct, although the base of the sporangium is coherent with the margin of
the sporangial spike. In all of the other species of Botrychium, however, the spor-
angiophore branches, the degree of branching following very closely that of the

110 THE OPHIOGLOSSALES

sterile lamina. In the larger species, like B. virgintanum, many hundred sporangia
may be developed upon a single sporangiophore. In these larger and more special-
ized forms the sporangium is usually smaller and is better differentiated, always
having a more or less distinct pedicel.

The form of the sporangiophore in Helminthostachys is to some extent inter-
mediate between that of Ophioglossum and Botrychium, but on the whole comes
nearer to Botrychium. Vhe sporangia are densely crowded along the flanks of the
spike, thus forming two rows somewhat as in Ophroglossum, but they are very much
more crowded and are formed in groups or synangia which project free above the
surface of the young spike. The sporangia do not arise singly, but are borne upon
short branches or secondary sporangiophores which suggest the lateral branches of
the sporangiophore in Botrychium, but are far less regularly disposed. By the fur-
ther growth of the sporangia the axis of the spike is entirely concealed and a casual
examination would indicate that the sporangia were formed equally at all points of
its surface, but a study of the development shows that they are lateral in structure,
as they are in Ophroglossum.

THE DEVELOPMENT OF THE SPORANGIOPHORE,

The sporangiophore in both Ophroglossum and Botrychium becomes visible at
a very early period. In Ophioglossum moluccanum | have found that the spor-
angiophore can be recognized even earlier than Bower has stated for O. vulgatum
and QO, reticulatum. A median section of a very young fertile leaf in O. moluccanum
is shown in fig. 56, D. The apex of the leaf has scarcely become free and the apex,
as well as nearly the whole of the
adaxial surface, is made up of
large columnar meristem cells, of
which it is difficult to say that
any one is the single apical cell
of the leaf. The leaf trace is al-
ready evident, passing into the
base of the young leaf, which is
strongly inclined forward so that
the real apex of the leaf is not
directed vertically upward, but is
on the adaxial side of the leaf
rudiment. The apex of the young
sporangiophore arises from the
tissue immediately below the apex
of the sterile segment, and the
whole of the adaxial portion of

Fic. 81. the leaf below the apex of the
A. Longitudinal section of young sporophyll of Ophioglossum moluccanum, YOUNG sporangiophore may be said
still inclosed in the stipular sheath, sk X50. to belone to the latter and not

B. Apex of sterile lamina. sp, sporangiophore. 8 : :
C. Apex of sporangiophore. 125. to the sterile portion of the leaf.
D. Transverse section of a very young sporophyll, showing dichotomy of There is thus practically a dichot-

apex. X125. omy of the apex of the young

sporophyll, and the two branches (viz, the sterile segment and the sporangiophore )
are structures of equal rank. It would thus appear that the old view put forward
by Mettenius of two equal branches of the fertile leaf is probably the correct one.
It is probable that younger stages than those figured by Bower for O. vulgatum and
QO. reticulatum would show the same condition of affairs that we pointed out in

THE ADULT SPOROPHYTE ialal

O. moluccanum and O. pendulum, and the conclusion that the young sporangiophore
is an outgrowth of the sterile part of the leaf is the result of the subsequent rapid
growth of the upper sterile portion of the leaf, which thus carries its apex far beyond
the apex of the young spike.

The young ‘sporophyll i in O. pendulum (fig. 64, E) resembles that of O. moluc-
canum, except that all the parts are much larger. The apex of the young sporangio-
phore appears upon the adaxial side of the very broadly conical young sporophyll.

Bruchmann’s studies on Botrychium lunaria indicate that in this species the
separation of the fertile and sterile segments of the sporophyll is the result of a

dichotomy of the apex of the sporophyil at a very early stage in its development.

=a

E

- Young sporophyll of Ophioglossum pendulum. sp, the sporangiophore. X2.
. An older sporophyll. X1.

- A still older stage, showing venation of lamina.

- Base of a full-grown sporangiophore.

- Sporophyl! with rudimentary lamina, /.

The sporophyll, however, is larger at this time than is the case in Ophioglossum
moluccanum (Bruchmann 2, fig. 57).

The earliest stages in the development of the sporangiophore have not been
studied in Helminthostachys. Bower says (Bower 9, page 455):

A
B
Cc
D
E

“The origin of it is similiar (i. e., to Ophioglossum) and its early stages not
unlike. It appears at first as an outgrowth on the adaxial side of the sterile
frond, and it is curved over while young so that the actual apex is pointed
downward.”

In the latter respect it might very well be compared to the strongly bent-over
sporangiophore of Botrychium virginianum.

112 THE OPHIOGLOSSALES

—

After the separation of the fertile and sterile portions of the sporophyll the
sterile segment at first grows much more rapidly than the sporangiophore and soon
extends beyond it, so that the sporangiophore has the appearance of being merely
an adaxial appendage of the sporophyll. These changes in the relative importance
of the points can be very well shown by a study of the very large sporophylls of O.
pendulum. In this species the young leaf emerges from the sheath while it is still in
a very early stage of development. These young leaves (fig. 82) have a very thick,
fleshy leaf base, ending in the small pointed lamina, bent over and almost hiding the
young sporangiophore which is attached to its inner surface. This curved-over
form of the young sporophyll differs from that of Euophtoglossum, where the young
leaf is straight, and in this respect there is a suggestion of Botrychium or of the
true ferns. The young spike at this stage is almost equal in length to the sterile
lamina.

If the very young sporophyll of Ophioglossum moluccanum is examined, it will
be seen that the vascular bundle leaving it passes downward and } joins a young root
trace. Very soon after the bundle enters the young leaf it divides into two branches,
one of which passes into the base of the spike and the other and larger one into the
sterile section of the sporophyll. This latter bundle now divides again into two,
one of which passes to the dorsal side of the sterile segment while the other is turned
toward the ventral side of the leaf, which probably represents tissue belonging to the
sporangiophore. In the cross-sections of older leaves the petiole, which includes
the completely fused base or peduncle of the sporangiophore, shows three distinct
bundles, a large abaxial one and two smaller adaxial bundles. The former remains
undivided for some distance above the base of the insertion of the peduncle of the
sporangiophore. The two adaxial bundles divide into several branches, this begin-
ning just below the point where the lamina of the sterile leaf becomes differentiated
from the petiole. The lamina has its edges infolded so that it has a conical form,
open in front and inclosing the young spike (figs. 56, 57). The successive branching
of the two adaxial bundles follows in quick succession, and the outer bundles con-
tribute to the veins of the lamina; the inner ones pass upward into the peduncle
of the spike.

In a previous paper (Campbell 7) the conclusion was reached from the study of
a series of sections at different heights, taken from the full-grown sporophyll, that
the two adaxial bundles belonged exclusively to the spike. A study of the devel-
opment of the young sporophyll shows that this statement is not entirely correct
and that a considerable part of the vascular system of the sterile lamina owes its
origin also to branches from the two adaxial bundles before the latter enter the
peduncle of the sporangiophore. Of the two adaxial bundles, one represents the
original bundle of the sporangiophore derived from the primary forking of the leaf
trace; the other is derived secondarily from a subsequent division of the second
branch of the leaf trace, this also giving rise to the large abaxial bundle of the petiole.

THE DEVELOPMENT OF THE SPORANGIUM.

Much the most complete account of the development of the sporangium of the
Ophioglossacez is that of Bower (Bower 5), who has made a very exhaustive exam-
ination of the development of the sporangium in all three genera. My own studies
have been for the most part confined to Ophioglossum pendulum, O. moluccanum,
and Botrychium virgintanum. Burlingame (Burlingame 1) has more recently
examined the development of the sporangium in a species of Ophioglossum from
the Philippines, which was assumed to be O. reticulatum. Beers (Beers 1) has
also published recently a somewhat incomplete account of the sporangium in Hel-

THE ADULT SPOROPHYTE 113

minthostachys. Through the kindness of Prof. L. L. Burlingame I have also had
an opportunity to examine some of his preparations of Ophroglossum reticulatum and
Helminthostachys.

An examination of both longitudinal and cross sections of the young spike in
O. moluccanum (and this is true also of O. pendulum) shows that they agree entirely
with Bower’s account of the development in the species studied by him. There

Fic. 83.

A. Transverse section of a very young sporangiophore of Ophtoglossum moluccanum. 150.
B. Section of an older sporangiophore. 75. The shaded areas mark the “ sporangiogenic’’ bands.
C. Part of B, more highly magnified. The nucleated cells mark the sporangial region.

seems to be no question that, as Bower first pointed out, there is formed a continuous
band of tissue on each side of the sporangiophore, this band being the so-called
“sporangiogenic’’ band, from which the individual sporangia are differentiated
later. The sporangia arise from this sporangiogenic band at more or less definite
intervals, these fertile areas being separated by bands of sterile tissue. In the
sporangial areas periclinal walls are formed by which an inner mass of tissue, the

a

D

Fic. 84.

Development of the sporangium in O phioglossum pendulum. The darkly shaded nuclei in A mark the archesporium; 1, tapetum;
Sp, sporogenous tissue. A is a longitudinal section; B, a cross-section; C, part of B, more highly magnified; D, section of two
mature sporangia. X8.

archesporium, is separated from the outer cells which are to form the wall of the

future sporangium. ‘The inner cells constituting the archesporium later give rise

to the masses of spores. Between the young sporangia there lie partitions or septa

formed from the intervening sterile cells of the sporangiogenic band. ‘The cell

groups which form the archesporia and the sterile septa are derived from sister cells
8

114 THE OPHIOGLOSSALES

of the original sporangiogenic bands. Bower thinks that all of the sporogenous
tissue can not be traced back to a single primary archesporial cell, and that spore-
bearing tissue is formed secondarily by periclinal divisions in the cells outside
of the original archesporium. In some of the very young sporangiophores of O.
pendulum there can sometimes be seen a single large epidermal cell which may
possibly be the mother cell of a young sporangium, but it is very difficult to determine
this point satisfactorily.

After the archesporium is differentiated there is a rapid division in its cells and
there is thus formed a very large mass of cells, whose limits, however, are not always
very clearly marked. Later on the contents of these cells become denser and are
more easily distinguished from the surrounding sterile tissue.

The cells lying outside the archesporium divide rapidly both by longitudinal
and transverse walls and give rise to the thick outer wall of the sporangium. In lon-
gitudinal sections through the sporangium two rows of cells may be seen extending
from the mass of archesporial cells to the outside of the sporangium. These two
rows of cells mark the point where the transverse cleft arises by which the spo-
rangium opens at maturity. ‘The outercells derived from the archesporial complex

OES
SSS
eres

Fic. 85.

A, B. Young sporangia; C, an older sporangium of Botrychium virginianum. In C, the sporogenous
tissue is shaded; the nucleated cells adjoining form the tapetum.

do not develop into spores, but constitute the tapetum, which later becomes dis-
organized and forms a sort of plasmodium extending among the growing spore
mother cells, and is, no doubt, of great importance in the further development of
these. Bower thought that some of the inner cells of the archesporial tissue contnb-
uted to this plasmodium, but a further study has led him to the conclusion that this
is not the case and that all of the inner cells of the archesporium develop into spores.
This view is confirmed by the recent paper of Burlingame (Burlingame 1), who
investigated the development of the spores in O. reticulatum.

At maturity the sporangium opens by a transverse cleft whose position is already
evident in the younger stages of the sporangium. As the cells shrink with the drying
of the ripe sporangium the spores are crowded out through this cleft, but there is
no special mechanism like the annulus found in the sporangia of the higher ferns
which facilitate the dispersal of the spores.

Our knowledge of the development of the sporangium of Botrychium has been
based largely upon the study of B. lunarra. 1 have investigated with some care the
development in B. virgintanum, which differs mainly from B. /unarza in the smaller

THE ADULT SPOROPHYTE 15

size of the sporangium and the fact that it has a well-marked though short pedicel.
In the simplest forms of Botrychium, such as B. simplex, the sporangia are much
larger and are sessile.

In B. virginianum (fig. 85) the development of the individual sporangia begins
just about a year previous to their ripening, and if the plants are taken up about the
time the spores are shed the earliest stages of the sporangia will be found in the leaf
which is to expand the following season. At this time the sporangiophores in the
larger specimens are thrice pinnate, and the youngest recognizable sporangia are
borne at the tips of the branches. These young sporangia form slight elevations
which become smaller as they approach the tip of the segments, and if an exact
median section is made of one of these young sporangia it will be seen to have at its
apex a large pyramidal cell with a truncate base. Holtzman (Holtzman 1), states
that the whole sporangium may be traced back to a single cell and that the divisions
at first are like those of a three-sided apical cell. I have not been able to satisfy
myself as to the accuracy of this statement, but the youngest stages which I have
been able to find would not forbid such an interpretation, although there seems no
question that the basal part of the sporangium ts derived, in part at least, from the
surrounding tissue.

Fic. 86.
A. Sporangiophores of Helminthostachys. ‘The two lower figures seen from above. /, sterile appendages. 3.
B. Section of a young sporangium, showing sporogenous tissue, sp; tapetum, ¢; and wall, 7. (From preparation

made by Prof. L. L. Burlingame.)

The terminal cell of the sporangium is divided by a periclinal wall into a single
inner cell which forms the archesporium, and an outer one which contributes to the
wall of the sporangium. The outer cell rapidly divides and similar divisions occur
in the archesporium. By active growth in the basal part of the sporangium it pro-
jects more and more until it assumes the form of a projecting globular body with a
short stalk, thus differing strikingly from the deeply sunken sporangia of Ophio-
glossum. It is impossible to detect any definite succession of divisions in the arche-
sporium, which ultimately becomes changed into a large globular mass of cells with
the usual dense contents, separated from the outside of the sporangium by half a
dozen or more layers of sterile cells. The cells immediately adjoining the sporo-
genous tissue constitute the tapetum. Bower states that the tapetum is exclusively
derived from this outer sterile tissue, but it must be said that, in Botrychium vir-
ginianum at least, the limits between the sporogenous tissue and the tapetum are by
no means easy to detect. The wall of the ripe sporangium has from four to six
layers of cells and the dehiscence is by a vertical cleft, whose position may sometimes

116 THE OPHIOGLOSSALES

be recognized in the young sporangium by cells arranged very much as they are in
the sporangium of Ophioglossum. The stalk is traversed by a short vascular bundle
which can first be recognized when the sporogenous cells are pretty well advanced
in their development.

The sporangia of Helminthostachys on the whole more resemble those of
Botrychium than those of Ophioglossum. In the very young sporangiophore there
is developed a band of tissue on either side much like that in Ophioglossum (see
Bower 9, page 455): ‘Transverse sections of the fertile spike show that the spo-
rangiophores originate from certain groups of cells of this sporangiogenic band.
These young sporangiophores, however, project above the surface and later form
crowded projections which may undergo a greater or less degree of branching, so
that the number of sporangia borne upon a single one of these secondary sporangio-
phores may be considerable. These sporangiophores become irregularly lobed and
the final divisions of these develop into the sporangia in a manner which is very
similar indeed to that of Botrychium, but the individual sporangia are usually less
distinct. Bower's account of the further development may be quoted as follows:

“It has already been noted that the position and number of the sporangia
which they bear are inconstant. In early stages it is impossible to distinguish
the cells which will give rise to the sporangia, but from rather older stages it ap-
pears that the sporogenous groups, together with the superficial cells which cover
them are referable in origin to the segmentation of a single superficial cell. More-
over, the first periclinal division of the cells defines the whole of the sporogenous
tissue from the protective wall. As the sporangia grow older they project from
the surface of the sporangiophore. The sporogenous mass increases rapidly in
bulk, while the cells surrounding the sporogenous mass to the extent of several
layers assume the character of a tapetum which gradually becomes disorganized;
finally the sporogenous cells separate and divide into tetrads. As the sporangia
approach maturity the upper part of the sporangiophore may grow out into an
irregular rosette of lacinie of vegetative tissue.’

A study of the older sporangia of Helminthostachys shows that the tapetum is
extraordinarily developed, constituting a very thick layer surrounding the mass of
spores (fig. 86). The clusters of fully developed sporangia are often very regular
in form (Fe. 86, 4), and remotely suggest the synangium of a Marattiaceous fern.

Parr ll THE MARAT BIALES:

The members of the second order of the Eusporangiate—the Marattiales—
resemble quite closely the typical Leptosporangiate. Both in the form and venation
of the leaves and in the development of the sporangia upon their lower surface they
recall the common ferns. But the structure of the sporangium is very different,
and both in its structure and development the sporangium shows certain evident
resemblances to that of the Ophioglossacez.

The Marattiaceous type is a very old one, and this fact lends a special interest
to these few survivors of the ancient Paleozoic fern flora. Like the Ophioglossacezx,
the leaves of the Marattiacez are thick and fleshy in texture, but usually firmer than
is the case in the Ophioglossaceez. Some of the smaller species of Danea are only
2 or 3 decimeters in height, but the larger species of Marattia and Angiopteris are
among the largest of the ferns. The latter, which is common in the eastern tropics
and extends to Australasia, is a noble fern whose great caudex, covered with the
persistent leaf bases, is nearly as big as a barrel, a the gigantic leaves reach a
length of 5 or 6 meters, with stalks Sieoet as thick as a man’s arm. In the dense,
wet forests of Tjibodas in Java, for example, the development of this fern is espe-
cially luxuriant, and groups of them form one of the most striking features of this
rich, tropical flora.

The Marattiacee frequent, for the most part, the moist, shady forests of the
tropics, where they form a characteristic feature of the vegetation. Along the steep
banks of moist, shady ravines or streams they sometimes occur in profusion.

The number of living Marattiacea* is small, some authorities recognizing
only about thirty species. “There 1s, however, a good deal of difference of opinion
as to the number of species in some of the genera. ‘This is especially true of
Anguopteris, which many authorities consider to have only one single, extremely
variable species, while others recognize many species. One of the genera, Marattia,
is widespread throughout the tropics of both hemispheres, where there are about 25
species. (See Bitter 1, Christensen 1.) One of these, M. douglasii, extends to the
Hawaiian Islands, where it is a common and conspicuous fern. Angropterts is
widespread throughout the tropics of the old world and reaches beyond the tropics
into Australia and southern Japan. Archangiopteris, with a single species, 4.
henryt, 1s a recently discovered form occurring in southwestern One. Kaulfussia,
also a monotypic species, occurs throughout the Indo-Malayan region and extends
as far as the Philippines. The genus Danea is exclusively neo- tropical and com-
prises about 20 to 25 species, most of which occur in the West Indies, northern
South America, Central America, and Mexico. A sixth genus, Macroglossum, from
Borneo, has recently been described (Copeland 1).

Of these, Kaulfussra is the most aberrant, differing markedly from the other
genera in the form and venation of the leaves, as well as in the shape and position
of the synangia. Kaulfussia and most species of Danea have dorsiventral rhizomes,
while the other genera have an upright, radially-constructed caudex.

The gametophyte, in all of the investigated species, is a large, dark-green,
fleshy thallus, much resembling superficially such a liverwort as Pellia. The re-
productive organs are very much like those of Ophioglossum, and chlorophyll is

formed in abundance in the gametophyte. The large liverwort-like gametophyte
— — -- - - = ———- - —— =
* Christensen (I) recognizes 62 species of Angiopteris, 1 of Archangiopterts, 26 of Danaea, 1 of Kaulfussta, and 28 of Marattia.

117

118 THE MARATTIALES

and the character of the reproductive organs are marked indications of the primitive
nature of these ancient ferns. The embryo also shows many points in common with
that of the Ophioglossacew. As in the latter, the organs of the young sporophyte
are all of epibasal origin and the vascular system in the young sporophyte belongs
exclusively to the leaf and root, the stem being entirely destitute of a proper stele.

In Danea a short suspensor Is usually developed, but the other genera have as
yet shown no examples of this.

The sporophyte is very much alike in its early development i in all of the Marat- .
tiacew. ‘The young plant consists at first mainly of the primary leaf and root, which
are traversed by a single axial vascular strand as in Ophioglossum moluccanum, but
a stem apex is developed at an early period, although it remains relatively incon-
spicuous.

Kaulfussia, Danea, and Archangiopteris are all ferns of moderate size and
comparatively simple structure; but Marrattia, Angiopterts, and Macroglossum
are very large, and the arrangement of the vascular bundles in the stem becomes
exceedingly complex, corresponding to the numerous bundles in the enormously
developed leaves.

The form of the leaf in the Marattiacee ranges from a perfectly simple leaf in
Danea simplicifolia to the gigantic decompound leaves of Angtopteris and Marattia.
Most of the species of Danea (and this is true also of Archangropteris and Macro-
glossum) have simply pinnate leaves, while in Kaulfussta the leaves are palmately
divided into from three to seven leaflets, the larger leaves looking curiously like a
horse-chestnut leaf in outline, whence the specific name. The ternate form, which
is often found in Kaulfussia, recurs in the early leaves of the other genera and is
sometimes retained in quite large leaves in Marattia (plate 12, B). This recurrence
of the ternate leaf form suggests Helminthostachys and the ternate species of
Botrychium. ‘he leaves are usually quite smooth, but in the earlier stages there is
sometimes a sparing development of hairs and scales. The latter are especially
noticeable upon the leaves of the young sporophyte in Danea.

The leaves are furnished at the base with very conspicuous fleshy stipules
which remain adhering to the stem after the leaves fall away, and these leaf bases,
with their attached stipules, more or less completely cover the surface of the stem.
As the leaves fall away they leave a characteristic scar marked by the remains of the
vascular bundles. The leaf base as well as the stalks of the leaflets shows a more or
less marked enlargement, recalling the pulvinus which occurs so commonly in the
Ig eguminose. It is at this point that the leaf stalk separates, the smaller divisions
of the leaf often breaking away from the main or secondary rachis, in the same
fashion as the main leaf stalk falls. In the large species of Marattia and Angiop-
teris this enlarged leaf base with the two thick, fleshy stipules curiously resembles
in shape and size the hoof of a horse.

The leaves when young are coiled up in the same fashion as those of the typical
ferns and their venation in general is decidedly fern-like, the ultimate veins being
dichotomously branched and the venation very much like that of Helminthostachys
or certain species of Botrychium. In Kaulfussia, however, the venation is reticulate
and strikingly like that of the typical Dicotyledons. In its earlier stages, however,
there is a marked resemblance to the venation of Ophioglossum.

The fleshy leaves do not, as a rule, show a very large development of mechanical
tissues; but there is developed, especially in the larger leaves, a thick layer of hypo-
dermal tissue, which is usually sclerenchyma, somewhat like that of the typical ferns,
but may be thick-angled tissue or collenchyma, such as is common in many flow-
ering plants. A marked anatomical feature is the presence of large mucilage ducts.

THE GAMETOPHYTE 119

i THE"GAMETOPHY TE.

The first account of the germination and development of the gametophyte
in the Marattiacea was published by Luerssen (Luerssen 2), who studied the
germination in Marattia cicutefolia and in Angiopteris. Not long afterward the
Dutch botanist, Jonkmann, published an account of the development of the prothal-
lium in both Marattia and Angiopteris. His original paper (published in Dutch,
but afterward translated into French) gives an extremely satisfactory account of the
germination and development of the prothallium and reproductive organs (Jonk-
mann 1). Somewhat later he also published a preliminary account of the germina-
tion in Kaulfussia, but apparently the work was never published in full (Jonkmann
2). In 1892 Farmer (Farmer 1) described the gametophyte and embryo in Ang:-
opterts evecta and in 1894 the writer (Campbell 3) gave an account of the prothallium
and embryo in Marattia douglasi collected in Hawaii. Two years later Brebner
(Brebner 2) described the prothallium and embryo in Danea simplicifolia. In
1908 the writer published an account of the prothallium and young sporophyte of
Kaulfussia (Campbell 9) and in 1909 a preliminary note was published in regard
to Danea (Campbell, 10).

The following account of the germination is based mainly upon the work of
Jonkmann. I have, however, examined the early germination stages in Marattia
douglasit for comparison with Jonkmann’s account, and, so far as my experiments
went, it agrees entirely with the species described by Jonkmann.

The ripe spores of the Marattiacez are small and may be either of the bilateral |
type or tetrahedral (radial). According to Jonkmann, the bilateral spores are much
more abundant in Marattia than the radial spores, but in Angiopteris the radial
spores predominate. The wall of the spore (see Jonkmann 1, pp. 203, 204) shows a
differentiation into an inner membrane or endospore and a middle layer, the exospore,
which is often found divided into layers. There is a very thin external coat, the
perispore or epispore, which is generally thrown off in the early stages of germination
or even before germination begins. All of the membranes except the epispore are
colorless, while the latter is a more or less pronounced yellowish brown tint. The
surface of the spore is roughened by small papillz which arise from the exospore.
The spores contain no chlorophy ‘ll, but there is a considerable amount of oil present,
which appears as drops of varying size, and there are also other granular contents—
starch and albuminous granules. The nucleus lies in the center of the spore and
is connected with the peripheral protoplasm by delicate protoplasmic filaments.
Germination begins quite promptly under favorable conditions and within about
a week the spores, which hitherto were quite colorless, begin to show a greenish
tint, due to the development of chlorophyll. Jonkmann states that the chlorophyll
appears first as flocculent masses near the nucleus, but these apparently amorphous
masses are really composed of very small, faintly tinted chromatophores, which lie
between the large oil drops and rapidly increase in size and depth of color as
germination proceeds, their number increasing by the usual division. The chloro-
plasts later become very conspicuous and are distributed in the periphery of the now
very much enlarged spore, the outer membranes of which are ruptured so as to
expose the endospore, containing the nucleus and numerous large and conspicuous
chloroplasts. Starch granules are also to be seen in most cases.

The cell remains undivided until it has attained a size many times greater than
that of the spore. The first division wall, which is formed about a month after the
spores are sown, is transverse both in Angiopteris and Marattia, and, like that in
the germinating spore of Ophioglossum, divides the primary cell into two nearly

120 THE MARATTIALES

equal parts (fig. 87, 4). A rhizoid may be cut off either before or after this first
transverse wall is developed, but frequently no rhizoids are formed until a much
later period, as in Ophroglossum. The primary rhizoid, when present, is formed
much as in the typical ferns, the papilla from which it develops being cut off from
the larger cell, and it contains little or no chlorophyll. ach of the primary prothal-
lial cells divides, in typical cases, by a longitudinal wall, so that the young gameto-
phyte consists of four cells, arising quadrant-wise (fig. 88, 4), and closely resembling
corresponding stages in Ophioglossum, except for the absence of chlorophyll in the
latter. Where the young plants are crowded or light is deficient, as for instance
when the germination occurs within the sporangium, there is a tendency to the
development of a filament, a phenomenon often met with also in the typical ferns.,

Usually one of the upper pair of cells in the four-celled stage assumes the role
of an apical cell, and for some time, as in the typical ferns, there is growth from a
two-sided apical cell (fig. 88, C). As soon as the apical cell is established, it grows

Fic. 87.

A. Two germinating spores of Marattia fraxinea Smith. X200. The remains of the spore membrane can be seen.

B. Young gametophyte of same species. 75. (A, B, after Jonkmann).

C. Marattia sambucina Blume. X 1.5.

D-H. M. douglasii Baker. D-F, X 1.5; G, H, X3. G,H, show the young sporophyte.

D and E represent the same prothallium after an interval of about a year. F is the ventral view of E. &, adventitious bud.

very much as it does in such a liverwort as Aneura and produces a thallus of the
same form and structure. But as the prothallium grows older a periclinal wall
is formed in the apical cell, and in the outermost of the two cells thus produced
there is a longitudinal wall dividing it into two equal cells, and from this time on
it is impossible to recognize a single apical cell in the prothallium, the apex of which
is occupied by a group of apparently similar marginal initial cells.

At first the prothallium has a spatulate form, but before the single apical cell
is replaced by the group of marginal initials the outer cells of the younger segments
grow more rapidly than the inner ones, so that they project beyond the apical cell,
which thus comes to lie in a depression between the two lobes, and the familiar
heart-shaped form so commonly found in the prothallium of most ferns is established .
The marginal initial cells vary in number with the width of the depression in which
they lie. In a horizontal section they appear oblong in form, but in the vertical
sections made they have a semicircular outline (fig. 88, D, £).

MF

THE GAMETOPHYTE 1D

Basal segments are cut off by a wall extending the whole depth of the prothallium
and the segment thus cut off is divided at once by a horizontal wall into a dorsal and
ventral cell of nearly equal size (fg. 88, E, d,v). Cell divisions are more active in the
ventral segments, more manifestly so at some distance back from the apex. It is due
to this more active cell division in the ventral segments that the strongly projecting
cushion-like mass of tissue is formed upon the ventral surface of the prothallium,
upon which the archegonia later make their appearance. The superficial cells of
both surfaces of the prothallium have a thick cuticle which often makes it difficult
to embed the prothallia without bad shrinkage. From the under side of the prothal-
lium numerous rhizoids are developed, which in the case of Marattia and Angiopterts
are unicellular and thin-walled, but in Danea become divided into several cells.
Sometimes there seems to be no definite apical growth in the early stages, but on the
other hand Jonkmann states that both of the superior cells may function as apical
cells, thus inaugurating the early dichotomy of the young prothallium, and even a
third branch may arise from one of the inferior quadrants, which assumes the
character of a third apical cell.

Among the leptosporangiate ferns, the forms which most nearly resemble the
Marattiacex in the development of the gametophyte are the Osmundacez, especially

Se |
\ ] \SV7 F \J
NEES
Fic. 88.
A-C. Three young gametophytes of Angiopterts. sp, spore membrane. A, X200; B,C, X160. (After Jonkmann.)
D, horizontal, E, longitudinal, sections of the prothallium apex of Marattra douglasti. x x, initial cells.

the genus Osmunda (Campbell, Mosses and Ferns, 2d ed., pp. 347, 348). In
Osmunda there is often a tendency also to the formation of a massive structure at an
early stage in the development, due to the formation of cell divisions in three planes,
so that the prothallium becomes from the first more than one cell thick. This
tendency in the Marattiacez becomes much more pronounced as the gametophyte_
grows and very soon there is evident a very thick midrib, which often becomes
exceedingly conspicuous in the older gametophyte, unlike the typical ferns, where
the thickening of the prothallium is confined to the region which bears the arche-
onia. In the Marattiacee this thickening extends almost to the margin of the
prothallium, so that it is only at the extreme edge that the prothallium shows but a
single layer of cells. The very old prothallia in Marattia branch dichotomously
(fig. 87, E, F), and the process is entirely similar to that found in many thallose
liverworts. The original growing point becomes divided by the development of a
median lobe, thus inaugurating two growing points, and the midrib back of the
growing point forks in exactly the same Way as in many liverworts.
Besides this dichotomous branching, it is not at all uncommon to have adven-
titious buds developed upon the margin of the thallus. These form small secondary

122 THE MARATTIALES

prothalhia, which may be detached and become independent plants; or reproduc-
tive organs may be developed upon them, usually only antheridia, while they are
still connected with the mother plant. The prothallia are very long-lived and
apparently may grow indefinitely so long as the archegonia are not fecundated. |
kept prothallia of Marattra douglasit for nearly two years, during which time they
grew vigorously and finally reached a length of over 2 centimeters. At the end of
two years there was no indication of the slightest decrease in their vigor.

The prothallia are moncecious, although it is not uncommon to find small
prothallia which bear only antheridia. ‘They are very deep green in color, which
together with their more massive texture makes them easily distinguishable from the
prothallia of the ordinary ferns, and they very often look more like such a liverwort
as Pellia or Anthoceros. he prothallium of Angropterts very closely resembles that
of Marattia, but is often somewhat shorter. ‘The difference in shape in the prothallia
of the form studied by Jonkmann (4.
pruinosa var. hypoleuca) and the Cey-
lonese form studied by Farmer and my-
self may be taken as an argument in favor
of recognizing a specific difference between
these two forms.

The archegonia in both Marattia and
Angiopterts, so far as my own observations

Fic. 89. extend, are confined to the lower surface

Two gametophytes of Angiopteris with young sporophyte of the midrib. Jonkmann, however, states

attached. em, embryo; cot, cotyledon. <3.

that occasionally he observed archegonia

developed upon the upper surface as well. The antheridia, while more abundant

upon the lower surface of the prothallium, are quite commonly met with also upon

the upper surface and are not restricted to the midrib, but may be found quite near

to the margin. The rhizoids in both Angiopterts and Marattia are probably always

unicellular, and their walls, which are quite strongly cutinized, are dark brown in
color.

cot

THE PROTHALLIUM OF KAULFUSSIA.*

The prothallia of Kaulfussra are usually much larger than those of either
Marattia or Angiopterts. They are very massive, strongly resembling a Pellia or
Aneura. The specimens described here were collected in Java tn a small ravine
near the foot of the volcanic mountain Salak. The youngest prothallia found
were about 5 millimeters in length and, like the older ones, were decidedly elon-
gated, with a deep sinus in front (fig. go, 4, B). There were a few antheridia
occupying the forward part of the thick midrib, which is very largely developed
in Kaulfussra, as it is in the other Marattiacee. The older prothallia are relatively
somewhat broader and these larger ones usually bear archegonia. Only in a
few cases were young antheridia found upon the prothallia with the archegonia.
Whether this is always true could not be decided from the small number of prothallia
found. The antheridia in Kaulfussia seem to be strictly confined to the lower sur-
face of the midrib and occupy much the same position that the archegonia do.
After the antheridia have matured and discharged the spermatozoids, archegonia
arise in the same position in regard to the apex. Unlike most ferns, the walls of the
empty antheridium do not become discolored, so that they are easily overlooked.
Careful examination of the sections of the older prothallia, however, will almost
always show the empty antheridia and it is probable that the prothallia are usually

* Kaulfussia Blume = Christensenia Maxon.

THE GAMETOPHYTE 123

proterandrous and not dicecious, as might be supposed from a casual examination.
The margins of the large prothallium are more or less irregularly lobed and it is not
unlike that of Osmunda, but as in the other Marattiacezx the wings of the prothal-
lium are several cells in thickness near the midrib, and only at the extreme edge
are they reduced to a single cell in thickness.

The full-grown prothallia are a centimeter or more in length and nearly as
broad. One very large specimen was found (fig. go, F). This bore a young sporo-
phyte with two fully developed leaves, and the prothallium measured nearly 2.5
centimeters in length by 1.75 in extreme width, and was also very thick. A second
archegonial cushion was present, but whether this was due to a forking of the original
apex, such as not uncommonly occurs in Marattia and Angiopteris, was not deter-
mined, although this was very probably the case.

Fic. 90.—Kaulfussia esculifolia Bl.

A. Young gametophyte. X4.

B. Apex of A, showing the antheridia, G20.

C. An older gametophyte, with archegonia, 2. X4

D. Apical region of an older gametophyte; x, apical cell.

E. An older gametophyte, with young sporophyte attached. cot, cotyledon;
r, root.

F. Two views of a large gametophyte, with attached sporophyte, natural size.

G. Rhizoid. X50.

H. Apex of rhizoid, more highly magnified. A single nucleus only is present.

The rhizoids are stout and they have thick but quite colorless walls. They
o'ten show apparently transverse septa and the extremity is not infrequently forked
(fig. 90, H). An examination of these rhizoids shows that these septa are not the
result of true cell division, as only one nucleus can be found in the whole rhizoid.
As the nucleus is large and conspicuous, and only one can be seen, it looks as if the
formation of septa is secondary and not connected with cell division. The structure
of the apex of the prothallium is exactly as in Marattia and Angiopteris. The
apical meristem shows the usual row of marginal initial cells, of which one (fig. go,
D, x) is often somewhat larger than the others and may possibly represent a single
apical cell.

124 THE MARATTIALES

THE PROTHALLIUM OF DAN/AA.

In July, 1908, the prothallia of three species of Danea were collected in Jamaica.
As the genus Danea has received comparatively little attention, especially as regards
the gametophyte, it seemed very desirable to secure as complete a series of the pro-
thallia and young sporophytes as could be done, and to this end the trip was made
to the West Indies. The genus Danea is confined to the American tropics and
comprises, according to Christensen, 26 species of extremely characteristic ferns.
The type is evidently an old one, as some of the fossil Marattiacez are closely allied
to the living genus Danea and may possibly be referred to it. The only account of
the prothallium hitherto published, so far as I am aware, is the paper of Brebner
(Brebner 2) on D. simplictfolia, a species from British Guiana.

In 1897 I collected a small number of specimens of prothallia of Danea, prob-
ably D. jenman:, and in the summer of 1908 the same locality was visited, as well
as some others in the same district, and material of three species was secured. These

A. Three gametophytes of Danza jenmani Underwood. X2.

B. Three young gametophytes of D. jamaicensis Underwood. 4.
C. Four large gametophytes of D. jamaicensis. X2.

C, 1, shows four groups of archegonia, Q.

collections were all made in the vicinity of Cinchona, a mountain station at an eleva-
tion of about 5,000 feet. As I have found in collecting other Marattiacez, the most
favorable collecting ground for the prothallia is upon moist, clayey banks where the
fruiting plants are growing. In the shady crevices in such positions a careful search
will usually be rewarded by the discovery of numerous young plants, and with these
there are often associated prothallia in various stages of development. Brebner
described the prothallia of D. stmplicifolia as being nearly circular in outline, but
very few of the prothallia of the species collected by me showed this form; but they
were usually decidedly elongated, sometimes very strongly so, and were, as a rule,
very much larger than the specimens of D. simplictfolia described by Brebner.
The three species collected by me were D. jamatcensis Underwood, D. jenman:
Underwood, and D. elliptica Smith. In all three species the larger prothallia are
usually decidedly elongated and very irregular in outline, often showing conspicu-

ous leaf-like marginal lobes, like those occurring in the prothallia of Osmunda and
Gleichenia.

THE GAMETOPHYTE 125

The germination of the spores and the early stages are quite unknown in
Danea, but probably resemble those of the other genera which have been studied.
To judge from the younger stages collected, there is a good deal of variety of form,
as is the case also in the other Marattiacee. The youngest specimens collected
belonged to D. jamarcensis. ‘These were very broad in outline and unsymmetrical,
one wing of the prothallium being much better developed than the other (fig. 91, B).

Fic. 92.—Four gametophytes of D. elliptica Smith. X2. B-D, seen from below.

Fig. 92 shows some older specimens of D. ell: ptica which were greatly elongated,
the very much attenuated posterior region being quite thin and delicate in texture,
with no midrib and the archegonial cushion being confined to a small region just
back of the growing point. The marginal region in these young prothallia was
composed of a single layer of cells and a considerable portion was made up of but

(e
\
Fic. 93.
A. Young gametophyte, probably developed from an adventitious bud of Danwa jamaicensts.
X20. ' antheridia.
B. Large gametophyte of D. e//iptica, with two sporophytes. X2.
C. Multicellular rhizoid. 100.
D. A cell of the rhizoid, showing nucleus, 7. X210.

two layers, while the mid region, where the antheridia and later the archegonia are
developed, was not more than four to five cells in thickness. In general the prothallia
of Danea are more delicate in texture than those of the other Marattiacee that
have been studied.

126 THE MARATTIALES

A midrib usually begins to form at an early period and in the older prothallia
may become very conspicuous, sometimes reaching a thickness of eight to ten cells.
The margin, as we have seen, is always more or less irregular in outline and often
develops large leaf-like lobes which are particularly conspicuous in D. samaicensts
(fig. g1, C), but are noticeable also in the other species. The large prothallia, which
are sometimes nearly 3 cm. in length, are often branched (fig. 92, D); the branching

Fic. 94-

A, archegonium; B, antheridium of Marattia douglasti. n, neck canal cell ;
v, ventral canal cell; 0, egg; m, mantle cells.

is sometimes unmistakably a true dichotomy, but again it seems to be adventi-
tious. In one large prothallium of D. ;amarcensts of very irregular form, four groups
of archegonia were present, widely separated from each other. It could not be cer-
tainly determined whether these arose from a repeated forking of the original apex
or whether one or more of them was of adventitious origin (fig. g1, C).

Fic. 95.

Antheridium of Angiopterts. X275. m, mantle cells; 0, operculum.

\, B. Longitudinal sections. C. Transverse section. D, E. Surface view.

The apex of the prothallium in the younger stages is usually indented by a
sinus, but in the older ones the heart shape is almost completely lost and the apex
may even project as a rounded protuberance, bearing the archegonia upon its lower
surface, or it may be fan-shaped, with little or no indentation at the growing point.

The prothallium is the usual dark-green color found in the other Marattiacex,
but as we have seen is rather more delicate in texture. Of the three species
examined, Danea elliptica resembles more nearly the prothallia of the other Marat-
tiacee in the thickness of the central portion, which may show from eight to ten

THE GAMETOPHYTE 127

layers of cells. The form and division of the apical cells 1s exactly the same as in
the other Marattiacee. Stiff brown rhizoids are developed upon the lower surface
and are mainly confined to the midrib, over which they may be evenly distributed,
or there may be certain regions of considerable extent which are quite destitute of
them. The rhizoids in all the species which have yet been examined are truly
multicellular, as was correctly shown by Brebner to be the case in D. simplicifolia.
The nuclei are not very large, but can be readily demonstrated.

The distribution of the reproductive organs is not always the same. Apparently
the usual course of development is present here, the antheridia appearing first upon
the lower side of the midrib and the adjacent points of the prothallium; later,
nearer the apex and upon the lower side, the archegonia arise. Sometimes, how-
ever, as in the other forms, there is a more or less marked tendency to dicecism and
some of the smaller prothallia seem to bear only archegonia or anthertdia, and it is
common to find antheridia developing exclusively upon the lateral lobes, which

ee

Fic. 96.—Kaulfussta.

A. Section of a young prothallium, showing two antheridia on the ventral side (reversed in the figure). So.
B-E. Longitudinal sections of antheridia.

F-H. Transverse sections. G, H are surface views showing the opercular cell. , mantle cells. 180.

I. Cell from interior of prothallium, showing the endophyte.

apparently never produce archegonia at all. Antheridia may also occur upon the
upper surface, but this is not common, and in no cases were archegonia seen except
upon the lower surface of the midrib. The reproductive organs are sometimes
found in great numbers upon the older prothallia, the whole lower surface of the
midrib being beset with archegonia. Quite as often, however, extensive areas along
the midrib are quite sterile and the archegonia thus appear in patches, separated by
sterile intervals.

THE ENDOPHYTE OF THE MARATTIACE#:.

In all of the Marattiacez that I have studied, an endophytic fungus very much
like that which occurs in the prothallium of the Ophioglossacew has been found
occupying the central cells of the prothallium in nearly all cases. The endophyte
which infests the green prothallium of the Marattiacea, when compared with that
found in the strictly saprophytic prothallia of the Ophioglossacee, shows some
differences which are probably not without significance. The structure of the myce-

128 THE MARATTIALES

lium and its general behavior are so much like the form which occurs in Ophio-
glossum as to leave little room for doubt that the two forms are either identical or
very closely related. The conidia (fg. 96, /), while occurring in the Marattiacex,
are perhaps less frequent, but in form and structure are much like those of the
endophyte of Botrychium. The most noticeable difference is the absence of the
digestive cells, 1. e., those that contain the varicose swollen mycelium. No evidences
were found in the Marattiaceaw of the destruction of the fungus by the cells of the
host and it is likely that the endophyte in these green prothallia is more nearly a
true parasite than is the case in the saprophytic gametophytes of the Ophio-
glossacew. In the infested cells of the green gametophyte the starch and chroma-
tophores are destroyed by the action of the endophyte, but the nucleus of the cell
remains intact.
THE SEXUAL ORGANS.
THE ANTHERIDIUM.

The development of the antheridium, except for the details of spermatogenesis,
was correctly described by Luerssen and Jonkmann for Marattia and Angropterts.
The other genera agree closely with these in the essential structure of the antherid-
ium. The development of the antheridium in the Marattiacee agrees very closely
indeed with that of Ophroglossum.

Fic. 97.—Development of the antheridium in Danaea.

A. Section of prothallium, bearing antheridia on both surfaces. 80.
B-H. Longitudinal sections. X3z00. E-H, D. elliptica; the others, D. jamaicensis.

The mother cell of the antheridium, as in Ophioglossum, divides first by a
periclinal wall into an outer cell, the primary cover cell, and an inner one, from which
the mass of spermatocytes is developed (figs. 96, 97). The mother cell of the anther-
idium shows much the same variation in form as that of Ophioglossumi, sometimes
being relatively broad and shallow and at other times deeper and narrower (fig. 96,
B,C). The first division in the inner cell is usually transverse, but in the broader
type of antheridium this first wall may be longitudinal. The primary wall is followed
by a second one at right angles to it and the four cells thus formed are again divided
so that there result eight nearly equal cells. The first wall occasionally is somewhat
oblique, but even jn such cases the regular quadrant and octant walls arise at right

THE GAMETOPHYTE 129

angles to the primary division wall. The next divisions are, usually at least, anti-
clinals (fig. 97, G), but before long the periclinal walls also are developed and sub-
sequent divisions do not show any recognizable regularity in their sequence; there
seems to be a good deal of variation in this respect, even in the same species. The
number of cells ultimately formed varies a good deal, but the number of spermato-
cytes finally developed is probably never so great as that found in some of the
Ophioglossacee. Kaulfussia, both in the size of the antheridium and that of the
spermatozoids, approaches nearest to Ophioglossum. ‘The number of spermatozoids
may reach several hundred, fifty or more being visible in a single section of a large
antheridium, and nearly or quite as many may sometimes be found in Danea,
where, however, the spermatozoids are much smaller than in Kaulfussza.

In the cover cell the divisions are all anticlinal and horizontal sections or
surface views show that the successive walls are arranged spirally in a way suggesting
the segmentation of a three-sided apical cell. The last-formed wall cuts out a small,
nearly triangular cell, the opercular cell (fg. g5 D, E, 0). In most cases, at least,

Fic. 98. Fic

- 99-
Ripe antheridium of D. jamaicensis. m, mantle cells.

A. Transverse section of three young antheridia of D. jamaicensts.
o, opercular cell. 350.

B. Surface view of the two youngest ones. 0, opercular cell. X380.

this opercular cell is thrown off when the antheridium opens, leaving a small
aperture through which the spermatozoids are ejected. Surrounding the mass of
spermatocytes is a layer of mantle cells cut off from the adjacent cells of the prothal-
lium. These mantle cells, at the time of the opening of the antheridium, become
very much distended and project strongly into the cavity of the empty antheridium
(fg. 100, B, m). They no doubt play an important part in the dehiscence of the ripe
antheridium.
SPERMATOGENESIS. (Plate 2, figs 38-44.)

Of the Marattiacea, Kaulfussia is the most satisfactory for studying the details
of spermatogenesis, owing to the much larger size of the spermatozoid. The
development of the spermatozoids agrees very closely in its details with that of
Ophioglossum. If the spermatocyte is examined just before the final division the
two blepharoplasts can be seen and the division of the cell into the two spermatocytes
proceeds very much as in Ophioglossum. After the final division the nucleus of the
spermatocyte appears coarsely granular and, as in other cases, no nucleolus can be

seen. In favorable cases the blepharoplast is visible as a round body, stained
9

130 THE MARATTIALES

rather strongly and lying near the nucleus. The blepharoplast soon takes on the
curved form and becomes much extended and the cilia begin to develop from it
before the nucleus has materially changed its shape.

The nucleus now becomes slightly pointed at one end and begins to stretch
out so as to appear somewhat crescent-shaped, very much as in Ophioglossum and
as it does in other ferns that have been described. With this change in the form of
the nucleus, the blepharoplast becomes still more elongated and strongly colored
and the cilia increase in length. The nucleus of the spermatozoid in Kaulfussia
is less elongated than is usual in the ferns, and in this respect, as well as in its larger
size, it more nearly resembles Ophioglossum than it does the other Marattiacez.
The granular appearance of the nucleus is maintained until the spermatozoid is
almost fully developed, when there seems to be a fusion of the chromosomes so that
it appears almost homogeneous; this is accompanied by a noticeable diminution in
the size of the nucleus. The nucleus occupies only the large posterior coil of the
spermatozoid, while the anterior portion, which shows about two coils, is composed
of the blepharoplast with probably a certain amount of other cytoplasmic matter.

:
2

Fic. 100.
A. Cross-section of a ripe antheridium of D. jamatcensts.
B. Cross-section of an empty antheridium; m, mantle cells.
C-D. Surface views, showing opercular cell.
All figures X 350.

In Marattia and Angiopterts (plate 2, fig. 44) the nucleus of the spermatocyte
becomes much more extended and the whole spermatozoid is more slender than in
Kaulfussia. Indeed there is very little difference between the appearance of the
spermatozoids of Angropterts and Marattia and those of the typical leptosporangiate
ferns. Some observations were made also upon Danaea, in which the spermatozoid
is somewhat intermediate in character between that of Angiopteris and Kaulfussia
(plate 2, figs. 42, 43). In size the spermatozoids are more like those of Angiopterts,
but the nucleus is much less elongated and the general form of the spermatozoids
is more like that of Kaulfussia.

THE ARCHEGONIUM.

The archegonium in the Marattiacez, like the antheridium, very much resembles
that of Ophioglossum, but the neck of the archegonium is even less developed than
in the latter. Jonkmann (Jonkmann 1) has given a fairly complete account of the
development in Marattia and Angiopteris, and Farmer (Farmer 1) has described
and figured the archegonium of the latter genus.

Usually, at least, the archegonium is developed only upon the cushion of tissue
back of the apex, the young archegonia arising in acropetal succession. Jonkmann

THE GAMETOPHYTE 131

states, however, that he has found them also upon the upper surface of the prothal-
lium, but none of the specimens I have examined have shown this. The mother
cell of the young archegonium is scarcely distinguishable in form from the young
antheridium and like it is first divided by a periclinal wall into an outer cover cell
and an inner cell, the latter usually, but not always, divided subsequently into a
central and a basal cell (figs. 101-103), as in Ophioglossum and in the typical ferns.
Sometimes the mother cell of the archegonium is seen in transverse section to have
been cut out very much as the axial row of cells arises in the archegonium of the
Hepatice. There seems no question that the so-called mother cell of the archego-
nium in all the ferns is really homologous only with the axial row of cells of the
bryophyte archegonium, the four rows of neck cells being a further development
of the terminal cap cell of the liverwort archegonium.

The inner of the two primary cells, as we have already stated, may have a basal
cell cut off from it before the further divisions arise, by which the egg cell and the
canal cells are divided. The neck canal cell is very broad and may become divided
into two cells, but usually the division is confined to the nucleus, which probably
divides in all cases. The ventral canal cell cut off in the usual fashion from the egg

7 a 5 55
is, with the exception of Dana, very large and conspicuous, thus differing from

Archegonia of Angiopterts. 275. 6, basal cell; 0, egg; v, ventral canal cell.

Ophioglossum, where the ventral canal cell is so dithcult to demonstrate; but in
Danea there is the same imperfect development of the ventral canal cell that is
found in Ophioglossum.

As the archegonium approaches maturity a layer of mantle cells, much like
those which Serena the antheridium, is cut off from the tissue surrounding the
venter of the archegonium. The archegonia of Marattia douglass: are onfined to
the lower side of the midrib and begin to form at some distance back of the grow-
ing point; so far as can be determined, any superficial cell of the apical meristem
can develop into an archegonium. The mother cell divides, as we have seen,
into three superimposed cells, of which the lowest, ), usually divides later by
vertical walls, and forms the base of the archegonium. From the central one, by
transverse divisions, are formed the canal cells and egg, and from the uppermost
the neck. Compared with the typical ferns, the most striking differences are the
short neck and the very broad canal cells. The cover cell undergoes division into
four, by two intersecting vertical walls, as in Ophioglossum, and each of these four
cells then undergoes division by nearly horizontal walls, but the cells remain short,
so that the neck projects very little and there are only three or four cells in each row;
occasionally there may be only two. Jonkmann states that, as a rule, two of the
rows of the neck contain three cells and two contain four, but that there may occa-
sionally be as manyasfive. The neck canal cell often shows a trace of a division and
there may be an actual division wall formed (fg. 101, D), but in Marattia douglass:

132 THE MARATTIALES
this is not ordinarily the case. In one instance in this species | observed a division by
a vertical wall, so that two neck canal cells were formed, placed side by side, in a way
recalling very strongly the division of the neck canal cell described by Jeffrey in
certain species of Equisetum ( Jeffrey 2). The central cell is divided again by a hori-
zontal wall into two nearly equal cells, the lower one being the egg, the upper one the
ventral canal cell. The mature egg is nearly elliptical in form, the upper third being
almost homogeneous and quite colorless, forming the so-called receptive spot. The
nucleus is of moderate size and does not stain very strongly. The archegonium of
Angiopteris closely resembles that of Marattra, but is perhaps somewhat narrower
(fig. 101).

Jonkmann fgures the archegonium of M. cicutefolia, which shows that this
species also is, in the relative size of the canal and neck cells, very much like Angi-
opteris. Farmer thought that a basal cell was usually, if not always, present, and my
own studies tend to confirm this.

Fic. 102.

Archegonia of Kaulfussia. X210. b, basal cell; 0, egg; v, ventral canal cell; 1. ¢., neck canal cell.

In Kaulfussia (fig. 102) the archegonia form, as a rule, only after the antheridia
have ceased to develop. Compared with the other Marattiaceze they are decidedly
large, and in this respect Kaulfussia approaches Ophioglossum. Like the mother
cell of the antheridium, there is a good deal of variation in the width of the young
archegonium in Kaulfussra. Some of the narrower types recall the archegonium
of Anthoceros and emphasize the resemblances between the archegonium of the
Anthocerotacez and the eusporangiate ferns. The neck of the archegonium is very
short, each of the four original neck cells often dividing only once, so that there may
be but two cells to each of the four rows. More commonly, however, there is a

Fi. 103.

Young archegonia of Danea elliptica. 350.

second division in some of the cells, so that each row consists of three cells. The
nucleus of the broad neck canal cell probably always divides, but the number of
available specimens was too small to decide whether or not there is ever formed a
division wall between these, although it is not at all unlikely that this may occur.
The ventral canal cell is conspicuous and equals its sister cell, the egg, in breadth.
In the peripheral portion of all the axial cells of the archegonium there are many

small granules of starch. Jonkmann figures similar starch granules in both Marattia
and Angiopterts.

THE GAMETOPHYTE 133

The archegonium in Danaea, while resembling that of the other Marattiacez,
in its position and early development shows some marked differences, the signifi-
cance of which is not quite clear. The division of the mother cell into the primary
neck cell and the central cell follows in the same way as in the other forms, but the
inner cell, usually at least, does not have a basal cell separated from it, but develops
at once into the egg cell and canal cells. “The absence of the basal cell is by no means
unknown, however, among the other Marattiacee. [he primary neck cell gives
rise to the usual four cells, each of which divides into three or four, and exception-
ally into five. There is a marked elongation of the inner cell before its separation
into the central cell and the neck canal cell (fig. 103, D).

Fic. 104.
A, young, B, nearly mature, archegonium of D. jamaicensis. X360. :
C, D, cross-section of a young archegonium of same species. D shows the four primary neck cells.

Up to this point there is nothing peculiar in the development of the archegonium
in Danea, but while in most of the other Marattiacez a conspicuous ventral canal
cell is formed, its sister cell being the egg, in Danaea the formation of a definite
ventral canal cell could not be satisfactorily demonstrated. In a number of cases
(fig. 105; plate 2, fig. 45) a small nucleus-like body could be seen in a large, clear

Fic. 105.

Three mature archegonia of Danea elliptica. 350.
A and B show traces of a ventral canal cell; v, in B, a division of the neck canal cell.

space just above the somewhat contracted mass of protoplasm, with its large and
conspicuous nucleus, which constitutes the egg cell; but this ventral canal cell
nucleus, if such it is, is very different in appearance from the large and conspicuous
one found in the other Marattiacez, and in the absence of any division stages its
nuclear nature must for the present remain somewhat doubtful.

There is somewhat the same uncertainty in regard to the primary division of the
neck canal cell. ‘his possesses a large and conspicuous nucleus which in large and
apparently mature archegonia was still undivided. In a few cases a division of the
protoplasm in the neck cells was observed; in other cases, without any such division,

134 THE MARATTIALES

a second body of rather indefinite outline and staining much less strongly than the
lower nucleus could be made out; but up to the present time I have not been able
to satisfy myself that the division of the neck canal cell nucleus, which always
occurs in the other Marattiacew, takes place here. The very uncertain nature of the
ventral canal cell recalls strongly the condition of affairs in Ophioglossum, where it
is equally difficult to demonstrate satisfactorily the presence of a true ventral canal
cell.
FERTILIZATION.

It has not been possible to follow in detail the process of fertilization in the
Marattiacew, but several stages were found in preparations of Marattia douglasit.
The entrance of the spermatozoid into the archegonium was not seen, but in a
number of cases the material had been killed immediately after, and twice spermato-
zoids were found which had penetrated into the egg. In these cases the spermato-
zoid was quite unchanged in form, but had not yet entered the nucleus itself. One
case was observed where there were apparently two nuclei in close contact, but the
egg nucleus was much contracted and it is doubtful whether this was really a normal
appearance. It is probable that the details of fertilization are quite similar to those
observed in other ferns.

THE EMBRYO 135

i tHe EMBRYO:

The study of the embryogeny of the Marattiacee offers many difficulties.
Fertilization does not seem to be of common occurrence and a very large number of
prothallia must be examined before even a small series of embryos can be secured;
moreover, the earlier stages of the embryo are peculiarly liable to shrinkage in
preparing them for sectioning and it is exceedingly difficult to secure really satis-
factory preparations of these early stages.

A marked peculiarity of the young sporophyte, which was first shown by Luers-
sen and Jonkmann for Marattia and Angiopteris, is the orientation of the primary
organs of the young sporophyte with reference to the archegonium. The primary
or basal wall in the embryo is always transverse, as it usually is in Ophioglossum,
instead of being vertical as in most of the typical ferns. The first leaf, instead of
being formed from the portion of the embryo nearest the archegonium, as it is in
the common ferns, arises from the half of the embryo which is turned away from the
archegonium, and grows straight upward, bursting through the prothallium upon
its upper surface, instead of appearing upon the lower side of the prothallium and
curving upward. The external organs of the young sporophyte are differentiated <

Fic. 106.—Marattia douglastt.

A. Two longitudinal sections of a young embryo. bb, basal wall. 200.
B. A similar section of an older embryo. cot, cotyledon; r, root initial.
C. Three transverse sections of a much older embryo, showing junction of the two first leaf traces. 50.

much later than is the case in the Leptosporangiates, and the Marattiacez in this
respect closely approach the Ophioglossacez.

It has been generally assumed that, as in the leptosporangiate ferns, the cotyle-
don and stem are of epibasal origin, the root and foot hypobasal. This conclusion
was reached by both Jonkmann and Farmer, and my early studies on Marattia
douglasit led me to the same conclusion. A further study of this species, however, |
as well as an examination of the embryos of Angropteris, Kaulfussia, and Danaea,
has shown that this is not the case, but that the whole of the hypobasal region is.
devoted to the formation of the foot, and the root is developed secondarily from the,
epibasal region, from which are also derived the stem apex and the cotyledon.

While in the typical ferns the young organs of the embryo at a very early stage
show a definite apical growth, the apical cells being readily traceable to the primary
octants of the embryo, this is by no means so readily shown in the Marattiacez.
In the later stages, such initial cells can be seen in the root and stem at least, but the
relation of these initial cells of the root and stem to the early divisions of the embryo
is very difficult to determine. In M. douglas: (Campbell 3) I stated that there

136 THE MARATTIALES

was probably a single initial in the stem and in the primary root, and Farmer also
thought that a single root initial was always present in Angropteris, but concluded
that such an initial cell was not present in the stem of the young sporophyte. Breb-
ner (Brebner 2) says that in Danea simplictfolia such a single initial cell seemed
to be always present in the stem, and my studies on Angropterts, Kaulfussia, and
Danea indicate that a single initral is developed at an early period in the stem apex
and persists until the sporophyte has developed several leaves.

Before any division occurs in the embryo the fertilized cell increases markedly
in size, after which there is formed the horizontal basal wall (figs. 106, 109, b 4).
‘This is probably followed at once by the median wall (except in Danaea), so that the
embryo at this stage 1s divided into four approximately equal quadrants (see Jonk-
mann 3, fig. g).

The genus Danea, at least this is true for D. yamaicensis and D. elliptica,
differs in the early divisions of the embryo from the other Marattiacee. The e
cell after fertilization elongates in a way which closely resembles that found in
Botrychium obliquum (Lyon 1). ‘The primary hypobasal cell either divides no further
or only once and forms a short suspensor, so that all the organs of the young embryo,
including the foot, are really of epibasal origin. As yet no trace of such a suspensor
has been found in the other Marattiacez.

THE EMBRYO OF MARATTIA,

Luerssen (Luerssen 2) found the one-celled embryo and young plants of
Marattia cicutefolia, but was not able to procure the older embryos. The writer
(Campbell 3) succeeded in procuring several stages of the embryo in Marattia
douglast, and somewhat later Luerssen described and figured some of the earlier
stages in M. fraxinea and M. wetnmanniafolia. These, so far as | am aware,
complete the list of records upon the embryo of Marattia.

The fertilized ovum in Marattia douglasi: becomes much enlarged before it
divides and completely fills the venter of the archegonium. The granular contents
of the egg cell become evenly distributed without any apparent increase in quantity
as the fertilized ovum grows, so that the one-cell embryo contains comparatively
little granular contents, but the nucleus is very conspicuous. At the time of the
first easidn the young embryo is almost perfectly globular in form. I was unable
to find the stages immediately following this, but Jonkmann has hgured an eight-
cell embryo of M. fraxinea (see Jonkmann 3, fig. g). The basal wall is transverse
and this is followed successively by the median and transverse walls, so that the
globular embryo ts divided into approximately equal octants. From the hypobasal
half, which is nearest the archegonium, there is developed the foot alone, while all
of the other organs arise from the epibasal portion, which is turned away from the
archegonium.

The_youngest embryo (except the one-celled stage) which I found in M.
douglasit, is shown in fig. 106, A. This is about the same stage as the one shown in
Jonkmann’s figs. 11 and 13. Unfortunately this embryo was rather badly shrunken
in the process of embedding and the division walls were a good deal distorted, so
that it is rather hard to determine exactly their correct relation to each other; but
probably the wall 4} represents the basal wall and m the median wall. The
embryo has now lost its original globular form and become oval, the long axis lying
transversely. ‘he secondary divisions in the octants are mostly anticlinals, and the
first periclinals have just appeared in a few of the cells. Figure 106, 4, shows two
consecutive median sections. It will be seen that cell division is more active in the
epibasal portion than in the hypobasal region.

THE EMBRYO 137

In my original study of Marattra | concluded that the primary divisions resulted
in the establishment of the organs of the young sporophyte in a manner similar to
that in the Leptosporangiate, i. e., that the stem and leaf were derived from the
epibasal quadrant, the root and foot from the hypobasal ones. Farmer thought that
this was true for Angiopteris and Jonkmann assumes that it is the case also in
Marattia. A further study of my preparations, however, has led me to believe that
the whole of the hypobasal region is devoted to the foot, while the root, together with
the leaf and stem apex, are of epibasal origin. A large cell (fig. 106, 4) occupies
approximately the same position as the stem apex in the older embryo and it is
possible that this may be the apicaljcell of the stem, but in the absence of the inter-
mediate stages this can not be positively asserted. For a long time the embryo
retains the oval form and there is scarcely any sign of the young organs of the
sporophyte which in the leptosporangiate ferns are so early manifest; indeed,
Jonkmann states that there is no differentiation at all, but a ‘careful study of the
older embryo shows unmistakable indications of the definitive organs. The devel-
opment of the tissue in the epibasal region is not uniform, but somewhat to one
side of the center (fig. 106, B) there may be seen a group of columnar superficial
cells, which mark the position of the future growing point of the stem. Whether
one of these superficial cells is the
definitive apical cell it is impossible
to determine, but from a comparison
with the older stages, as well as with
corresponding stages of the embryo
in the other genera, it seems proba-
ble, at ieee that this is the case,
and perhaps this initial cell may be
traced back to the centrally placed
cell noted in the younger embryo. A
considerable portion of the epibasal
tissue is not included in the meri-
stematic region, which is derived Two cross-sections of an old embryo of Maratita douglasi1.
mainly, at least, from only one of the A passes through the stem apex, st, and base of cotyledon.
original epibasal quadrants. ‘tive ee Passes shrouginrone pct X200:
tissue adjacent to this meristematic region is made up of large cells with less dense
contents and smaller nuclei and differs in no way from the large cells of the foot, into
which this tissue insensibly merges and of which it may be said to constitute a part.

In the embryo figured, it was not quite certain whether the root apex had
begun to form or not. It seems probable that the cell r is really the apical cell
of the young root, but except for its position 1t was not noticeably different from the
cells adjacent; however,/as in Angiopteris and Danea there is no question that the
root originates in this position, it is probable that this cell is really the initial for the
young root and is cut out from the base of the epibasal tissue near its junction with
the foot. This marked endogenous formation of the root is very much like that in
the embryo of Ophioglossum moluccanum, but differs entirely from the superficial
origin of the apical cell of the root in the embryo of the Leptosporangiates.

The stem apex in the older embryo is of very limited extent, consisting of only
a few cellsyof which one, as we have said, is probably the definite apical cell, although
it must be said that this point is very difficult to decide, as all of the central cells
of this apical group look a good deal alike, but a careful study of both transverse
and longitudinal sections seems to point to one of these as the apical cell, which in
shape is a good deal like that in the stem apex of Ophioglossum. In longitudinal

Fic. 107.

138 THE MARATTIALES

sections this is somewhat wedge-shaped, the narrow end turned outward and the
broad base below. In cross-section this cell is nearly square in shape (fig. 107, 4, x)
and there may be seen a fairly regular series of four segments cut from the lateral
faces. From the broad truncate base of the cell, segments are also cut off which
contribute to the inner tissue of the stem.*

Much the greater part of the epibasal meristem contributes to the cotyledon,
which is soon evident as a broadly conical protuberance, somewhat flattened on the
side adjacent to the stem apex and merging gradually on the outer side into the large-
celled tissue which adjoins the foot. To judge from the limited number of young
embryos which I could examine, it seems that the growth of the cotyledon is not due
to the activity of a single apical cell, but this point was somewhat uncertain.

By the time that the cotyledon is established, growth has progressed in the young
root, which now is seen to have a conspicuous apical cell, which divides rapidly
so that the root quickly elongates in a direction opposite to that of the cotyledon
(fg. 108). The apical cell of the primary root in M. douglass is not triangular in
outline, but more or less quadrilateral, whether seen in longitudinal or cross
sections (fg. 107, B). In form and segmentation it perhaps more nearly resembles
that of Danea than it does the tetrahedral apical cell which occurs in the young
primary root of Angiopteris.
Active cell divisions take
place also in the tissue of
the foot, which completely

> .
Wer hes = incloses the young root and
a ay MI oh becomes practically merged
BAT P with it, so that it is quite
S5 3 impossible to say, at the time
an

the root emerges, just how
much of the tissue of its
outer portion really belongs
to the root itself and how

BiG oe: much is derived from the

A. Section of an advanced embryo of Marattia douglasti, just before original tissue of the foot.

emergence of cotyledon. The latter is now no longer

B. The cotyledon, more enlarged. :

recognizable as such, the
young sporophyte apparently at this time being composed almost entirely of the
cotyledon and the very large root, with the stem apex, lying near their junction.
From a comparison with younger stages, however, it is perfectly evident that the
enlarged central region of the embryo at this time is composed mainly of tissue
belonging to the foot, which is, so to speak, perforated by the root in its downward
growth.

The development of the vascular bundles at a very early period is first evident
in the cotyledon, which almost as soon as it can be recognized at all is seen to have
a strand of procambium extending below it. If this procambium strand is traced
downward, it is seen to continue without interruption into the base of the root, exactly
as it does in Ophioglossum moluccanum. No trace of a procambial cylinder can be
found extending into the stem apex, which gives rise only to the parenchyma of the
central pith. This early development of the vascular bundles in the cotyledon and
root was correctly observed by Jonkmann and Farmer, both for Marattia and

*In a very recent paper in the Botanical Gazette (Feb. 1911), Miss Charles states that the apical cell of the
stem in Marattia alata is at first triangular in cross-section. In older sporophytes the single apical cell was replaced by
a group of initial cells.

THE EMBRYO 139

Angiopteris, but they seem to take it for granted that a vascular strand is also
developed in the stem; at any rate they make no reference to the absence of such
a vascular strand from the stem region. In my earlier study of Marattra, | supposed
that a strand was developed which belonged to the stem itself, but a further exam-
ination of many plants, after a study of this point in the other genera, has made it}
pretty clear that this supposed stem bundle really belongs to the second leaf, the
rudiment of which appears at a very early period.

THE EMBRYO OF ANGIOPTERIS.

In Angtopteris the embryo very early becomes more greatly elongated trans-
versely than is the case in Marattia, so that in a longitudinal section it appears as a

very much depressed oval (fig. 109); the epibasal region is larger than the hypobasal

GE. Ss

c

Fic. 109.

A. Two sections of a young embryo of Angiopteris. The cells were badly shrunken.
B. Diagrams showing arrangement of cells of same embryo.
C. An older embryo. 6, basal wall; st, stem apex; cot, cotyledon; f, foot.

and the quadrant divisions are often still evident. Whether octant divisions are
formed in all the quadrants could not positively be determined, but Jonkmann
states that such is the case. There can usually be found in the young embryo a
nearly centrally placed large cell (fig. 109, C, st), which probably is the initial cell of

the young stem. The position of this cell is not unlike that which occurs in the

Fic. 110.

Two longitudinal sections of an older embryo of Angfopteris. 200. The young root, r, is shown
in B. st, stem apex; cot, cotyledon; f, foot.

embryo of Equisetum, and at this stage there is also a certain resemblance to the em-
bryo of Botrychium virginianum. As the embryo grows it tends to assume a more
nearly globular form (fig. 110). The basal wall can still be imperfectly followed, the
hypobasal portion of the embryo being made up of the large cells forming the foot,
while above the basal wall the cell divisions are more active and the rudiments of

140 THE MARATTIALES

the stem and cotyledon can be recognized, although the embryo still retains its oval
outline. As in the embryo of Maratt:a, growth is most active in the central region
of the epibasal part of the embryo and there can generally be recognized a large
central cell, which is presumably the single initial of the stem apex, although, as
in the case of Marattra, it is not absolutely certain that a single initial cell is always
present. Cell division is especially active on one side of the stem apex, and this
area marks the position of the young cotyledon. ‘The limits of this growth area are

Fic. 111

A. Two longitudinal sections of an old embryo of Angiopteris. X75
B. Stem region of same embryo. 160.
C. Root apex. 160.

not very sharply defined and it is difficult to say whether it can be traced back to
a single quadrant or octant cell, but it is probably not always constant in its
position; indeed, the stem looks as if the stem apex and the cotyledon both arose
from the same quadrant, the second epibasal quadrant contributing, at least in
part, to the foot.

As seems to be true in all the Marattiacew, the root makes its appearance at a
comparatively late period and it is evident that the root, as in the embryo of Marattra,
is a strictly endogenous structure. The first indication of the root is the development

Fic. 112.

A. Longitudinal section of an advanced embryo of Angiopteris, cut in the plane of the lamina of the cotyledon. X50.
B. Cotyledon of same embryo, showing dichotomy of apex. 220.
C. Root apex of same. X220.

of a group of actively dividing cells, almost in the center of the embryo below the
stem apex. This meristematic region is probably always of epibasal origin, but it is
close to the basal wall and it is possible that sometimes it may arise below it. The
apical cell, which in the early stages almost always appears triangular in section,
becomes conspicuous and was recognized by Farmer in his study of the embryo of

THE EMBRYO 141

Angiopteris (Farmer 1). ‘The root initial now divides by regular segmentation and
the root apex pushes rapidly down through the underlying foot and ultimately
emerges on the lower side of the prothallium. In the meantime the cotyledon grows
actively and there is a rapid elongation of the whole embryo in a vertical direction.
As in the case of Marattia, it is difficult to prove that the cotyledon grows from a
single initial cell. The cotyledon has very much the form of that in Marattia,
growth being more active on the outer side, so that it curves over the stem apex
very much as the cotyledon does in the embryo of Botrychium virginianum. About
the time that the cotyledon is ready to emerge, the apex becomes flattened out and
(sometimes, at any rate) there is a true dichotomy of this apex (see fig. 112, B).

In the primary root there seems to be no question of the presence of the single
initial cell which, at first at least, has the tetrahedral form, but later on is apt to
have the base truncate, although it usually has three series of lateral segments.
I have not been able to confirm Farmer’s statements that the single apical cell is
later replaced by a group of similar initials, as in the later roots of the sporophyte,
although it is not at all impossible that such may sometimes be the case. ‘The
development of the embryo of the vascular bundles in the young sporophyte is
exactly the same as in the corresponding stages of the embryo in Marattia.

THE EMBRYO OF KAULFUSSIA.

So far as | am aware, no account has been published of the embryo in Kauw/-
fussia, except one of my own (Campbell 11). Only two young embryos were found,
so that it was impossible to follow in detail the early history of the young sporophyte.
The basal wall, as in the other Marattiacez, is transverse and, to judge from a
comparison of similar stages of the embryo in Marattia and Angiopterrs, all of the
organs of the young sporophyte in Kaulfussia, except the foot, are also of epibasal
origin. Figure 113, 4, shows a nearly median longitudinal section of the young
embryo. This is very much elongated transversely, and to judge from the position
of the cells the basal wall is probably followed by the median walls, forming nearly
equal quadrants. The large cell (st) in one of the epibasal quadrants corresponds
in position to the similar cell found in the embryos of the other genera and very
likely may represent the primary initial cell of the stem. The embryos, however,

ies
=:

Fic. 113.—Young embryos of Kaulfussia. 275.

<O

feo

Ne ee
A

A. Longitudinal section.
B. Three cross-sections of a similar embryo, 6, basal wall; 1, quadrant wall.

were too young to make clear the relation of the cotyledon and primary root to the
stem. Three nearly transverse sections of an embryo of about the same age are
shown in fig. 113, B. To judge from the structure of the older sporophyte at the
time when it first emerges from the prothallium, Kau/fuss:a agrees in the main with
Marattia and Angiopteris in the origin of the young organs of the sporophyte.

142 THE MARATTIALES
THE EMBRYO OF DAN-AA.

Brebner (Brebner 2) has described the older embryo of Danaea simplicifolia,
but did not secure the earlier stages. ‘The youngest specimens he figures closely
resemble in form a corresponding stage in the species studied by me, and the slightly
pointed basal region suggests the possibility of the presence of a short suspensor
in D. simplicifolra like that which I have found in D, jamaicensis and D. elliptica.
While my own collection of young embryos is not as complete as might be wished,
still enough stages were secured to show that at least D. amaicensis and D. elliptica

Fic. 114.—Danaa jamaicensis.

A. Archegonium containing a one-celled embryo. E. Three longitudinal sections of a four-celled embryo.
B. Outline of next section of same embryo. F. An older embryo, which was shrunken.
C. Three-celled embryo, showing suspensor, sus. G. Diagram of F, showing probable arrangement of cells.

D. Outline of next section of the same embryo.

differ remarkably from the other Marattiacez that have been studied in the develop-
ment of a short suspensor, thus showing an interesting analogy with the embryo of
Botrychium obliquum, described by Lyon (Lyon 1). Whether D. jenmani shows
the same peculiarity was not determined, on account of the failure to obtain the
young embryo of this species; but as in its later development it corresponds very
closely to the other species, it is highly probable that a suspensor is developed.

Fic. 115
A. A nearly median section of an older embryo of D. jamaicensis. ‘Che suspensor does not show in this section.
B. Three sections of a young embryo of D. elliptica. sus, suspensor. 200.

Before the first division takes place in the embryo, the fertilized ovum enlarges
~ to several times its original size and becomes decidedly elongated. The first division
wall, as in the other Marattiacez, is transverse, but of the two primary cells thus
formed the hypobasal one divides no further, or only once, and forms a short sus-
pensor which pushes up into the neck of the archegonium whose cells become more
or less completely disorganized (fig. 114, 4). The next division wall is a nearly
median one, in the epibasal cell, and this is soon followed by a second wall in each

ee ——

THE EMBRYO 143

of the epibasal cells, so that this portion of the embryo is divided into four nearly
equal quadrants. There is some evidence that these are followed by horizontal
octant walls, so that the epibasal region is thus divided into octants in much the same
fashion as obtains in the whole embryo in other Marattiacee and in the lepto-
sporangiate ferns. How far these divisions are constant can only be conjectured,
owing to the small number of young embryos which were available. The elongated
pear-shaped embryo in Danea appears very different indeed, in these early stages,
from the broadly elliptical and much depressed embryos of corresponding stages
in the other Marattiacee (fig. 114, C, D, E).

Fic. 116.—D. jamaicensts.

Three sections of an older embryo. 200. Section B is a nearly median section;
A is the next section in the series; C shows the suspensor, sus.

A further study of the embryos shows that all of the lower half of the epibasal
region, probably that derived from the four lower octants—1. e., the four octants
that were in contact with the suspensor—develops into the foot, while all of the
other organs of the embryo (leaf, stem, and root) arise from the four terminal octants.

Quite early in the development of the embryo, there appears the same centrally
placed large, cell which we have observed in the embryos of the other genera and
which, as we have seen, probably represents the primary stem initial. Brebner
concluded that a single initial was present in the stem of D. simplicifolia and this is
true of the three species examined by me. The initial of the stem in Danwa becomes

eel

i

Rios)
Be

Fic. 117.—D. elliptica.

Three sections of a large embryo. X150. sus, suspensor; sf, stem apex; cof, cotyledon; r, root initial.

very easily seen in the older stages and is perhaps more clearly defined than it is in
any other of the Marattiacee. Whether or not this cell can be traced-back to one of
the original terminal octant cells is difficult to say, but it is quite possible.

No single initial could be made out for the cotyledon, and it seems quite likely
that the position of the cotyledon is not always exactly the same, being determined
perhaps by the position of the embryo with reference to the light or to some other
factor. The cotyledon, as in Marattia and Angiopteris, first appears as a slight
prominence close to the nearly centrally placed stem apex, and there is soon visible

c

144 THE MARATTIALES

a group of actively dividing cells which constitute its growing point, but no one of
these can be certainly named as the apical cell (fg. 117, 3). The embryo now
rapidly increases in breadth until the apex is almost flat, except for the slight pro-
jection in the center, where are situated the stem apex and the young cotyledon.
The whole embryo at this stage may be described as “‘top-shaped.” The stem and
cotyledon occupy a comparatively small portion of this broad terminal area and
are surrounded by a ring of large absorbent cells, physiologically, at least, belonging
to the foot and merging insensibly into the similar cells which make up the lower
half of the embryo.

cot
I UIT be
eR eg

Biya el
THUS vy
wagnlatise:

STON
Bish

Fic. 118.—D. jamaicensis.

A, B. Two sections of a large embryo. 150. cot, cotyledon; st, stem; f, foot. C. Root apex of same embryo. 360.

As in the other Marattiacew, the very young embryo shows no trace at all of
the root and this appears only after the embryo has reached a comparatively large
size. The origin of the root 1s exactly the same as in the other genera and it is a
strictly endogenous structure. The single initial cell arises deep down in the tissue
of the embryo, usually below the cotyledon and probably from the same octant as
that from which the cotyledon is formed, but owing to the displacement of the
original division walls this can not be determined positively and it may be that the
position of the root is not always exactly the same. The apical cell of the root soon

ER
WEES

—_

Ran
part IT 1)

Fic. 119.—D. jamaicensis.

A. Two sections of an advanced embryo. 100. B. Stem apex of the same embryo. 220.

becomes conspicuous, but it does not usually show the triangular form as seen in a
longitudinal section, but appears more nearly square, as in Marattia. This root
initial cell is quite variable in form, but more commonly it appears in longitudinal
section with a truncate base (fig. 117, r). In transverse section it approaches the
triangular form, but is more or less irregular in outline. The lateral segments cut
off from the initial cell are large and contribute later to the root cap as well as to the
inner root tissues, and it is not impossible (as Farmer believes to be the case also

s*

THE EMBRYO 145

in Angiopteris) that sometimes more than one of these terminal cells function as
the apical cell.

As soon as the root apex is established its growth is very rapid and, as in the
other genera, there is a rapid elongation of the whole embryo, whose vertical diameter
very soon becomes greater than the transverse diameter, and ultimately the whole
embryo becomes very much elongated. In the axial region of the embryo just below
the stem apex there is a marked elongation of the central cells which might at first
sight be taken to represent the central vascular cylinder, but these elongated cells do
not give rise to vascular elements, but remain as elongated parenchyma and belong
really to the pith. The part of the foot which lies below the growing root apex
acts as a very massive root cap and 1s pushed down with the growth of the root until
the latter emerges from the lower side of the prothallium. The cotyledon in the
meantime grows actively upward and finally penetrates the prothallium, emerging

Fic. 120.—D. jamatcensts.

Five of a series of transverse sections from an advanced embryo. 200. 1 passes through stem apex; 5 shows apex of root .

on the upper side. ‘The growth of the stem is slight and the cotyledon and root form
nearly a straight line, as in the other Marattiaceew and in Ophioglossum, so that the
young sporophyte may be described as bipolar. The equatorial region is surrounded
by the large absorbent cells in contact with the prothallium and all of these may be
said to function as the foot, although it is impossible to say how much of this tissue

is derived from the original foot.

THE ANATOMY AND HISTOLOGY OF THE YOUNG SPOROPHYTE.

The young sporophyte, at the time the root emerges from the prothallium, is
very much alike in all of the genera (figs. 108, 111, 121). The cotyledon at this
stage is a thick, conical protuberance, strongly curved inward over the stem apex,
owing to the more rapid growth upon its outer side. Close to its base lies the
very limited growing region of the stem, adjacent to which is the rudiment of the
second leaf, which at this time projects very slightly above the level of the stem apex.
The cells of the latter, and also those of the young leaves, are evidently actively
growing cells with conspicuous nuclei and are quite different in appearance from the
large, transparent cells that compose the enlarged mid-region of the young sporo-
phyte. his is largely made up of the original tissue of the foot, but this tissue merges
insensibly into the basal region of the cotyledon and the upper part of the root,
these two organs forming in their growth almost a straight line. Whether or not
we term this middle region of the young plant the “‘stem,” it must be borne in
mind that it does not arise from the activity of the extremely limited meristem,
forming the true stem apex. The young sporophyte is traversed by a single conspic-
uous vascular bundle which extends through the cotyledon and root without inter-

10

146 THE MARATTIALES :

ruption, and it is quite impossible to say just exactly where the point of junction is.
In Angiopterts elongated tannin cells, which stain very strongly, accompany the
vascular bundle, both in the root and cotyledon; but these are either entirely wanting
or but slightly developed in Marattra and are quite absent from the young sporophyte
at this stage in the other genera. In the relation of the primary root and leaf, there-
fore, the embryo of the young sporophyte in the Marattiacew shows a most strikin
resemblance to the condition found in Ophioglossum moluccanum. The cotyledon,
as in Ophioglossum, is not to be looked upon as an appendage of the stem, but as an
organ Sul generis.

Almost as soon as the second leaf is recognizable, there is evident, connecting
it with the primary vascular strand, a short group of procambium cells, and the
stem apex is seen to occupy the space between these two leaf traces. No procambium
1s developed in the stem above the junction of the leaf traces, but the inner cells, derived
from the apical meristem, contribute solely to the medullary tissue of the sporophyte

(fig. 121, 4).

Fic. 121.—Danea jamaicensis.

A. Large embryo. cot, cotyledon; /*, second leaf. X50. C. Second leaf. X150.
B. Median section of cotyledon; /, epidermal scale. X95. | _D. Trichomes from apical region.

The first tracheary tissue arises in the mid-region of the young sporophyte and
consists of a group of short reticulate tracheids. From this point the development
of the tracheary tissue proceeds upward into the cotyledon and downward into the
root. The single strand of tracheary tissue in the cotyledon is seen to be continuous
with one of the xylem masses of the diarch root. “Phe second xylem of the root arises
somewhat later and is connected with the xylem of the second leaf. This second
xylem mass is decidedly smaller than the first one, at least in Danaea, where I have
studied this point carefully, and an examination of the other genera points to a
similar inequality in the xylems of these as well, but this may not always be the case.

THE COTYLEDON.

The cotyledon at a very early period bends strongly over the stem apex, very
much as it does in Botrychium virginianum, and very soon afterwards begins to
flatten out, so as to indicate the separation of the lamina from the petiole. The
flattening of the apex is followed, in many cases at least, by a true dichotomy, which
is soon repeated, so that the lamina becomes fan-shaped, with a strictly dichotomous
venation (fig. 87, G, H; fig. 127). This shows especially well in Marattra douglasi:.
In M. sambucina (fig. 87, C) the cotyledon is more nearly orbicular than in M.
douglasii, but the venation indicates a similar early dichotomy of the apex.

In Angtopteris, the form of the cotyledon is extremely variable (fig. 124).
Farmer states that it has a distinct midrib extending to the apex of the cotyledon

THE YOUNG SPOROPHYTE 147

and that the secondary veins are pinnately arranged with reference to the midrib.
These later veins, however, may show dichotomous branching. I made an examina-
tion of a considerable number of y oung sporophytes collected at the same place where
Professor Farmer secured his specimens, but very few of the plants that I collected
showed this pinnate venation in the cotyledon, although it is usually conspicuous

Fic. 122. Fic. 123.
Young sporophyte of Marattia douglasii still attached A. Young sporophyte of Kaulfussia attached to
to the gametophyte, pr; Natural size. gametophyte, pr. X2.

B. Cotyledon from another plant. 2.
C. A later leaf; st, stipule. 1.

in the second leaf. Figure 124, C, shows drawings of a number of the forms from
my collection, showing the variation from a strictly pinnate to a perfectly dichoto-
mous venation. Many of them show an intermediate venation, but with very few
exceptions, even where a midrib was present, this was forked at the"apex, indicating

Fic. 124.
A. Young sporophyte of Angropterrs, with three leaves. 1, the cotyledon. 2.
B. Young cotyledon. X20.
C. Three cotyledons, showing the variation in form. 3.

that there had been an early dichotomy. This primary dichotomy of the apex was
well shown in a section through a very young leaf (fig. 112, B) where there was no
question that such a dichotomy was taking place.

In Danea there is much the same variation in the form of the cotyledon as in
Angiopteris. Brebner’s figures of D. simplicifolia show that the cotyledon in this
species has a midrib with two lateral veins near the base, but sometimes the midrib
forks at the summit, indicating again the early dichotomy of the cotyledon. In one

148 THE MARATTIALES

of his figures, where there is no forking of the mid-vein, the lateral veins seem to
follow the margin of the leaf and rejoin the central vein, thus inclosing two large
areoles like those found in the cotyledon of Kaulfussia; no mention of this, however,
is made in the text. D. yamarcensts (fig. 125, 4) shows a very similar form and vena-

Fic, 125.

A. Four young sporophytes still attached to the gametophyte of Danwa jamarcensis. 2.
B. Young cotyledon of D. elliptica. X15.
C. An older cotyledon of D. elliptica. X3.5-

tion, but the cotyledon is larger and there is sometimes a forking of the lateral veins.
In this species also there may sometimes be found a fan-shaped lamina with true
dichotomous venation like that of Marattia, but as I had little material of this
species I can not say how common this form is. It is probable that an examination

Fic. 126.

A. Young sporophyte of D. jamaicensis, with four leaves,
slightly enlarged. 1, the cotyledon.

B. Base of the fourth leaf, showing stipules, st, and peltate
scale, se. X20.

of a large series of young plants would show examples of the same type of cotyledon
as in the other species. The cotyledon of D. ellrptica (fig. 125, B, C) is of much the

same form as that of D. jamaicensis, but the cotyledon is larger as a rule and the
venation may be more complex, although conforming to the same general type.

THE YOUNG SPOROPHYTE 149

The cotyledon in Kaulfussia (fig. 123) is spatulate in form and not unlike that
of Danea in shape and also closely resembles in outline the broader leaf forms of
Ophioglossum moluccanum. he resemblance to the latter is much increased by
the venation, which is reticulate and extraordinarily like that of the cotyledon of
Ophioglossum. As in Ophioglossum, there is usually a mid-vein, but this is not,
however, noticeably thicker than the laterals. ‘The latter, instead of extending
free to the edge of the leaf, are connected at their distal ends with the mid-vein so
as to inclose more or less elongated areoles. The central vein does not extend to the
tip but, as in Danea, divides into equal branches which join above so as to inclose

Fic. 127.

A. Lamina of young cotyledon of Marattia douglasii. 260.
B. Section of lamina of cotyledon. 300.

a terminal areole. A careful examination of the secondary veins shows that their
divisions are really dichotomous, as in the lateral veins of the other Marattiacez,
and some of the ultimate branches may reach the margin of the leaf, or more rarely
they may end freely within the areoles.

As the cotyledon develops there is more or less elongation of the petiole, which,
however, very seldom exceeds the lamina in length. The petiole is usually more or
less deeply channeled upon its inner face. In Marattia douglasi (fig. 133) the base
of the cotyledon is much enlarged just above the level of the stem apex, which is

Fic. 128.

A. Section of lamina of cotyledon of Kaulfussia, traversing one of the large stomata, sf. 100.
B. A young stoma.
C. An older one.

thus almost inclosed in a sort of cleft in the base of the cotyledon, very much as it is
in the case of Botrychtum or Helminthostachys. In Angiopteris there is but slight
contraction at the base and the stem apex forms a strongly oblique surface, hardly
covered at all by the base of the cotyledon. The base of the cotyledon is still more
conspicuously hollowed out in Danea and especially in Kaulfussia (figs. 136, 137),
and in the latter there is a circular ridge completely surrounding the stem apex,
exactly as is the case in the young bud in Ophioglossum moluccanum. ‘Traces of
this ridge can be seen also in Danea and Marattia, but this is much less conspicuous
than in Kaulfussia. In the latter this cavity is especially marked, so that one might
almost speak of a stipular sheath, and this resemblance to Ophioglossum in the

150 THE MARATTIALES

relation of the leaf base and stem apex, especially in connection with the Ophio-
glossum-like venation in Kaulfussia, is not without significance in its bearing upon
a possible relationship between the Marattiacee and the Ophioglossacez.

In all of the genera the lower part of the cotyledon and sometimes the stem
apex are more or less covered with hairs and scales. ‘These are less abundant in
Marattia and Angiopteris, where they are, for the most part, short hairs whose
terminal cells contain a great deal of tannin and stain very strongly. In Kaulfussta,
and especially in Danea, conspicuous scales of peculiar form are abundant.

. X D
Fic. 129.—Danea jamaicensis.

A. Section near base of lamina of cotyledon. X75. _D. An older stoma. 200.

B. Part of the lamina. st, stoma. 200. E. Cross-section of a peltate scale, from young cotyledon. X200.

C. Young stoma.

In Marattia douglasii the nearly cylindrical petiole is somewhat channeled on its
inner side and the single and nearly centrally placed vascular bundle appears almost
circular in section. The xylem forms a somewhat crescent-shaped body, completely
inclosed by the phloem, but the phloem is less developed upon the inner side and
the bundle closely approaches the collateral type. Tannin cells occur, but are not
so conspicuous as they are in Angiopteris. The lamina of the cotyledon is similar
in structure to that of the latter, the leaves differing mainly in the much smaller
development of the mesophyll, which is often reduced to a single layer of cells (fig.
127, B). The smaller veins have
the xylem reduced to a few—
one to three—small tracheids
situated upon the upper side of
the bundles, so that the bundles
are strictly collateral. Stomata
of the ordinary form occur upon
the lower surface of the leaf and
these sometimes show a series
of concentrically arranged cells

Fic. 130. about them.
A. Section of petiole of cotyledon of Angiopteris. 95. The petiole of the cotyledon
B. Vascular bundle. 200. The shaded cell is a tannin sac.

in Angiopterts resembles in sec-
tion that of Marattia, but it is slightly winged (fig. 130), and the tannin cells adja-
cent to the vascular bundle are more conspicuous than in Marattia.

In Kaulfussia (fig. 137, C), where the petiole is stouter than in the other genera,
the section is more nearly circular than in Angropteris, but it is also slightly winged,
these wings being developed almost to the proportions of stipules at the contracted

THE YOUNG SPOROPHYTE 151

basal portion. The vascular bundle has a greater development of xylem than in the
other genera and the xylem forms a band of considerable extent in the oval section of
the bundle. The structure of the bundle is concentric, but, as in other cases, the
phloem is better developed upon the outer side. Below the free base of the cotyledon,
where the trace enters the stem, there is a reduction of the inner phloem, or the
inner phloem entirely disappears, and the bundle there becomes truly collateral. No
definite endodermis can be recognized and the tannin cells found in the cotyledon
of Angiopteris are quite absent.

Fic. 131.

A. Section of petiole of cotyledon of Dana elliptica. X75.
B. The vascular bundle. 200.
C. Section of a peltate scale. X75.

The section of the petiole of the cotyledon in Danea (fig. 131) is nearly cir-
cular, and the wings found in the other forms are almost entirely obliterated. The
ground tissue is composed of undifferentiated parenchyma, with no trace of tan-
nin cells. The vascular bundle is circular in outline, with a small group of three
or four tracheids placed somewhat toward the inner side of the bundle, but sepa-
rated from the outside by about two rows of cells, probably phloem, but not
showing any differentiation. Small protophloem elements, staining darkly, can
be seen upon the dorsal side of the bundle and an occasional similar cell can be

Fic. 132.

A. Two longitudinal sections of a somewhat older sporophyte of M. douglasit.

B. Apical region of stem, showing apical cell and second leaf, /*. 200.
seen toward the ventral side, but most of the ventral surface is destitute of these.
The petiole broadens at its base, becoming flattened, and in this region the inner
phloem disappears and the bundle becomes collateral, as it is in Ophioglossum. The
tracheary tissue of the cotyledon in all of the Marattiacee is composed of slender,
reticulately marked tracheids, like those of Ophtioglossum. Sieve tubes are prob-

152 THE MARATTIALES

ably present in the phloem, but in material mounted in Canada balsam the sieve
tubes are very poorly differentiated.

Upon the cotyledon as well as upon the later leaves in Danaea very character-
istic peltate scales are developed. These arise as single club-shaped cells, the
swollen end of which is cut off by a cross wall. In the upper cell, which broadens
rapidly, a series of vertical walls arises, sometimes arranged very regularly (fg.
129, E). In the case figured there had evidently been two median, intersecting walls,
so that the cells were arranged in a somewhat quadrant fashion; more commonly
the divisions are less regular and the cells increase considerably in size by
further divisions. A section of an older scale may be seen in fig. 131, C. Stomata
are developed upon the lower surface of the cotyledon in all of the Marattiacez.
These have already been referred to in the case of Marattia, and in Angtopterts
they are very similar to those found in Marattia. In Danea, previous to the
formation of the stoma, there are several preliminary divisions, the cells being cut

Fic. 133- Fic. 134-

Three longitudinal sections of a young sporophyte of Marattia douglasii, Two nearly median sections of a young sporophyte of

cut in the plane of the cotyledon, cot. st, stem apex; r, root apex. X75. Angiopteris. cot, cotyledon; st, stem apex. i,
second leaf. X75. The bundles of the cotyledon
and primary root are continuous.

off in a spiral fashion, the last division resulting in the formation of the mother cell
of the stoma (fig. 129, C). The complete stoma appears, therefore, surrounded by
a series of somewhat concentrically arranged accessory cells (fig. 129, D). Similar
accessory cells, but much less developed, can be recognized in Marattia also.

The stomata of Kaulfussia have long been known for their great size and the
fact that they form permanently open pores, a peculiarity already developed in the
stomata of the cotyledon. These are very much larger than those of the other genera
and can be readily recognized by the naked eye as little dots. The guard cells
become very large (fig. 128) and strongly curved, so that the stoma appears almost
circular in outline, with a very large permanently open central pore. This large
pore is surrounded by concentrically arranged series of cells, suggesting that the
mother cell of the stoma is cut off very much as in Danaea, but material was want-
ing for a thorough investigation of this point.

THE YOUNG SPOROPHYTE 58)

THE STEM OF THE YOUNG SPOROPHYTE.

The stem apex projects very little or not at all, and occupies but a limited area
close to the base of the cotyledon. Its outer surface is nearly horizontal, except in
Angiopteris, where it is generally strongly inclined (fg. 134). There probably is
always a single apical cell. Segments are cut off from the sides, and very often also
inner segments, where the base of the apical cell is truncate. The lateral segments
also have, cut off from their inner faces, cells which contribute to the growth in length
of the stem, which remains, however, very short in the young sporophyte, the leaves
being very much crowded together. As we have already stated, no central cylinder
properly belonging to the stem can be demonstrated at this time, all of the procambial

Fic. 135.—Young sporophyte of Angfopteris.

A. Stem apex, showing single apical cell. X150.
B. Second leaf, /*, of same sporophyte.

Fic. 136.
A. Nearly median section of a young sporophyte of Kaulfussia. B. Another section of same, showing continuity of bundles ot
!*, second leaf; m, mucilage ducts; st, stem apex; pr, game- cotyledon and root.
tophyte. X about 20. C. The stem apex.

tissue belonging either to the cotyledon or to the root. In the older embryo of
Marattia douglasi the apex of the stem (fig. 139, B) is occupied by a group of rela-
tively large cells, which at first sight seem to be pretty much alike; but a careful
examination of these makes it probable that one of them may be considered as the
real initial cell. This, in cross-section, appears almost square and shows a fairly
regular segmentation. While it must be said that the segmentation is not so regular
that one can assert without question that all of the meristem is really due to the
activity of a single cell, I believe that this is probably the case.

My own investigations of the stem apex in Angiopteris have led to the conclusion
that there is a single initial cell here also in the young sporophyte, although Farmer

154 THE MARATTIALES

in his earlier studies of this plant failed to find a single initial cell; however, in a
more recent paper (Farmer 3) he has decided that a single apical cell is present in
the young sporophyte of Angropteris, and he gives figures of this. In longitudinal
section (hg. 134) the apical cell appears oblong, with a markedly truncate base,
while in transverse section it is imperfectly triangular in outline. ‘The apical cell
of the stem in Kaulfussra (fig. 136, C) is usually somewhat broader than it is in
Angiopteris, and closely resembles that of Ophioglossum moluccanum. It has a
broadly truncate base and is somewhat narrowed above. In transverse section it
approaches the triangular outline of the apical cell in Ophsoglossum, but the seg-
mentation is less regular and in this respect it is not unlike that of Angiopteris. The
stem apex was examined in three species of Danea, all of which seemed to agree

Fic. 137.—Kaulfussia.

A, B. Two transverse sections of a young sporophyte, above C. Transverse section of petiole of cotyledon. go.
level of stem apex, showing closed sheath formed by D. Vascular bundle of cotyledon, more enlarged.
base of cotyledon. /*, second leaf. X50. E. Second leaf.

closely in the form of the apical cell, which is much more definite in Danea than it
is in any of the other genera. Brebner’s account and figure of the apical cell in
D. simplicifolia agree closely with my own preparations of D. elliptica, D. yenmani,
and D. samatcensts.

The apical cell (fig. 140, 4), seen in longitudinal section, is very deep and,
unlike that of the other genera, is not usually, at least, truncate below, but pointed,
so that it closely resembles in form that of Botrychium or Helminthostachys. In
transverse section it also usually appears triangular, so that it is tetrahedral like
that of Botrychium. While the segmentation is somewhat less regular than in
Botrychium, nevertheless the limits of the younger segments can be followed without
much difficulty, especially in longitudinal sections, although the exact sequence of
the divisions in the segments themselves did not seem to be absolutely regular.

In all of the species the tissue derived from the inner cells of the segments of
the apical cell, or cut off from the base of the apical cell itself, remains as undif-
ferentiated parenchyma and contributes only to the central pith of the stem. [xcept

THE YOUNG SPOROPHYTE 155

that the leaves arise from the segments of the apical cell of the stem, and their
tissues are therefore indirectly derived from the stem apex, we may say that the stem
apex takes no part in the differentiation of the fibro-vascular system, which in the
young sporophyte is composed entirely of the leaf and root traces.

THE ROOT.

Only a small number of sections of the primary root were obtained in Marattia
douglasi, and these showed some variation, so that it is not possible to state posi-
tively what is the typical form of its apical cell, but there is no question that the
primary root grows from a single initial cell, as in the other genera. In longitudinal

section it appears oblong, with a broadly truncate base from which segments arise,
as well as from the lateral faces. [here seem to be regularly four sets of lateral

Fic. 138.

A. Nearly median section of a young sporophyte of Danea jamaicensis, passing through stem apex. X about 4o.

B. Another section of same, passing through second leaf, /*

C. Section of another similar sporophyte cut at right angles to that shown in A and B, and showing continuity
of bundles of cotyledon and primary root. pr, gametophyte; sc, scales.

segments, although cross-sections of the apical cell sometimes appear almost trian-
gular. The root cap is formed in part from segments derived from the outer face
of the apical cell, in part from similar segments cut off from the outer portion of
the youngest lateral segments of the apical cell. The central cylinder of the root
is formed in part from the basal segments of the apical cell, but the lateral seg-
ments also contribute to it (fig. 141, D).

In Angropteris (fg. 111, C) the apical cell in the earlier stages of the root may
appear triangular in longitudinal section, but in the later stages it is usually more or
less truncate.

The primary root in Kaulfussia, in the few cases where satisfactory sections
were made of it, did not show the tetrahedral apical cell, but this was truncate at the
base and in cross-section appeared four-sided (fig. 142). In this respect 1t seems to
approach Marattia. The primary root in all of the Marattiace is ordinarily diarch;

7

156 THE MARATTIALES

the statement (Campbell 3, page 14) that in Marattia douglasii the primary root
is tetrarch I have found to be based upon a mistake, the root which was so de-
scribed not being the primary root, but evidently one of the later ones. 1 have
occasionally found very strong plant-
lets in Danaea, where the primary
root was triarch, as it sometimes is
in Botrychium, and very commonly is
in Helminthostachys; but such spe-
cimens are not common. ‘The root
bundle is bounded by a conspicuous
endodermis, whose cells show very
YY |} 5 plainly the characteristic radially
ae thickened bands (figs. 143, en; 144).
The endodermis gradually loses its
definite appearance at the junction
of the root and leaf bundles, and |
have not been able to recognize it
Fi. 139- above the level of the base of the

A. Transverse section of a young sporophyte of Marattia douglasii. cotyledon, although it is not at all

st, stem apex. 150. impossible that with proper staining
B. The stem apex. 360. c .
it might be traced further up.

THE SECOND LEAF.
The second leaf begins to develop while the cotyledon is still small, and by the

time the latter ruptures the overlying prothallium tissue the second leaf is clearly

evident as a flattened cone, closely resembling the early stage
of the cotyledon. In Kaulfussra the second leaf arises quite
close to the cotyledon and on the same side of the stem apex,
so that the dorsiventral character of the stem is already indi-
cated at this early stage of development. In the other genera
the second leaf arises nearly opposite the cotyledon, but not

Fic. 140.

A. Stem apex of a young sporophyte of Dana jamaicensis, showing single apical cell. X10.
B. Second leaf from same.
C, D. Sections of primary roots, showing apical meristem, X18o.

exactly so, and the subsequent leaves form a spiral, and for a time at least, except

in Kaulfussia, the anatomy of the shoot is radial. This radial arrangement is
retained permanently in Marattia and Angropterts and also in some species of

THE YOUNG SPOROPHYTE 157

Danea, e. g., D. elliptica; but in D. jenmani and in D. yamatcensts, as well as in
most of the other species, the stem finally becomes dorsiventral, as it is from the
first in Kaulfussza.

The development of the second leaf is marked by an increased activity in the
apical meristem, quite close to the apical cell, and it is clear that the leaf arises from
the younger segments, but it is impossible to state exactly what the relation of the
young leaf is to the younger segments of the apical cell, or to say whether the whole

Fic. 141.

A-C. Three transverse sections of primary root of Marattia douglasit.
D Longitudinal section of apex of primary root.

of the leaf is the derivative of a single segment. When the young leaf can first be
distinguished it is elevated very slightly above the level of the stem apex and its
growing point 1s composed of a group of columnar cells. Sometimes, especially in
Danea, there may be recognized near the center of this group of cells a single,
somewhat larger one, which may be interpreted as a single apical cell, but this is not
always recognizable.

Fic. 142.

A, longitudinal, B, transverse, sections of apex of primary root of Kaulfussta. 200
C. Apex of second root.
D Transverse section of root apex.

Even before there is any noticeable projection of the leaf rudiment, there 1s
developed beneath it the beginning of the short strand of procambium which is to
form its vascular bundle, and this can be followed downward to a point below the
stem apex, where it joins the trace from the cotyledon. Above this junction there is
no evidence of procambium tissue extending into the stem apex, but the whole
tissue lying between the junction of these two primary vascular bundles and the
apical meristem of the stem is made up of undifferentiated parenchyma.

The outer surface of the stem apex may be nearly horizontal or (especially in
Angiopteris) it may be strongly inclined and a single fairly conspicuous initial cell

158 THE MARATTIALES

may usually be recognized without ditheulty. This cell is usually quite deep and
in all of the genera except Danea has a truncate base in longitudinal section. In
Danwa, however, the base is usually pointed and the cell closely resembles the corre-
sponding cell in Botrychrum, or the typical leptosporangiate ferns. The growth of
the stem is usually rather slow and the leaves of the young plant are much crowded.

In all of the forms examined, the tissue derived from the inner cells of the
segments and from the basal segments of the apical cell, where such segments were
formed, remained as undifferentiated parenchyma and contributed only to the
internal pith of the stem. Except that the leaves arise from the segments of the
apical cell of the stem and all of their tissues are therefore indirectly derived from it,
the stem apex of the young sporophyte takes no part at all in the development of
the fibrovascular system of the stem, which, except for the bundles of the roots, is
entirely composed of the leaf traces.

The second leaf in Angiopterts usually shows a pretty well-defined but slender
midvein, which may, however, fork at the apex, and this is true also of the third leaf.
It is in the third leaf, both in Marattia and Angiopterts, that the characteristic
stipules are first developed. ‘These appear as lateral wing-shaped bodies close to the

Fic. 143-

A. Section of primary root of Danaea jamaicensis. 70.
B. The vascular bundle. 175. en, endodermis.
C. Triarch bundle from a primary root of D. elliptica.

base of the petiole, partially inclosing the next youngest leaf and the stem apex.
The third leaf in Ang:opteris and several others succeeding it assume a more and
more pronounced lanceolate form with a prominent midrib and pinnately arranged
lateral veins which usually fork once. The margin of the leaf is serrate. After
several of these lanceolate leaves have been developed, leaves are formed in which
the base is provided with auricles, and these gradually pass into the next type of leaf,
which is ternate, the terminal leaflet being very much larger than the lateral ones
(plate 13, figs. 4, 5). These ternate leaves then pass by intermediate stages into
the pinnate form of the leaves of the adult plant.

In Kaulfussra the second and third leaves closely resemble the primary one,
except that they are somewhat larger (fg. 123). The second leaf develops well-
marked stipules which are found in all of the later leaves. The earlier leaves do not
show a definite midrib, though there is usually a delicate midvein at the base of the
lamina, but this vein forks usually about half-way up. In the older leaves (fg. 123,
C) there is developed a stout midrib, from which extend distinct pinnately arranged
lateral veins, much as in Angropteris, but these lateral veins are connected by a
system of anastomosing veins, so that the leaf most strikingly resembles that of a
typical Dicotyledon. It is not until a very late period that the leaves in Kaulfussia
assume the compound form of the older plant (plate 11, fig. 1).

THE YOUNG SPOROPHYTE 159

In Danea a dozen or more leaves may be formed before there is any branching
of the lamina. While the cotyledon may show an approach to the pinnate venation
of the older leaves, there is almost always a dichotomy of the apex of the slender
midvein, and this is generally true also for a number of the subsequent leaves,
although in these later leaves the midrib becomes well marked and the lateral veins
are developed apparently monopodially. In D. simplrcifolia the leaves remain
permanently unbranched, but in all of the other species the later leaves are once
pinnate. The intermediate leaves have the ternate form found in Marattia and
Angiopteris, and after a few of these, about two or three, have been formed, five
foliate leaves appear and the number of leaflets gradually increases, as new leaves
are formed, until the full number of leaflets is developed. The early ternate leaves
often have the terminal leaflet much larger than the lateral ones, and the leaf

Fic. 144.

1-5. Transverse sections from a series of a young root of Danea jamatcensis. 2 shows apical cell.
6. Section of bundle frem fully developed primary root. en, endodermis.

closely resembles the corresponding stages in Angiopteris. The petiole in most
species is more or less obviously winged. In Danea the stipules are (sometimes, at
least) not formed until the fourth leaf. In the fourth leaf (hg. 126, B), however,
they are well developed, appearing as two conspicuous wing-like organs with
serrate edges.

In all of the genera there is a root formed for each leaf in the earlier stages of
the sporophyte, but how late this continues was not determined. In the older
sporophyte more than one root may be formed for each leaf. In Kaulfussia the
second root 1s developed earlier than in the other genera, beginning to develop while
the second leaf is still very small, and in general the roots in Kaulfussra seem to
develop earlier than in the other genera. The second root is especially late in
developing in Danea, the very first rudiment of the root making its appearance
between the first and second leaves, after the latter is already quite well advanced.

160 THE MARATTIALES

Il. THE OLDER SPOROPHYTE.

The vascular system of the adult sporophyte in the Marattiacea is extremely
complex, especially in the larger species of Marattra and Angropteris. In Danea
and Kaulfussia it is simpler, but in these also the arrangement of the bundles in the
adult stem is by no means easy to trace. A thorough study of the condition in the
early stages of the sporophyte is therefore specially important for understanding
the much more complex arrangement of the bundles in the older plant.

In view of the conditions that we have found to exist in the Ophioglossacez,
and particularly the nature of the vascular system in the young sporophyte of
Ophioglossum moluccanum, a careful reinvestigation of the developmental history
of the vascular system in the young sporophyte of the Marattiacea, especially the
simpler and presumably more primitive genera Danaea and Kaulfussia, was very
much needed. To this end series of sections were made of young sporophytes of
both of the latter genera, ranging from individuals in which the second leaf was
still undeveloped to those in which a dozen or more leaves had been formed. These
series were fairly complete and made it possible to trace quite satisfactorily the evo-
lution of the vascular system in the young sporophyte of both Dana and Kaulfussia.
Brebner (Brebner 3) has given an accurate account of the distribution of the bundles
in the young sporophyte of Danaea simplictfolia, which agrees quite closely with the
arrangement of the bundles as I have found them in the species studied ne me.
Jeffrey (Jeffrey 3) has described and figured a few specimens of D. alata (7), but
his material was too incomplete to make the study at all satisfactory.

The available material of Marattia was much less complete, although a number
of stages were secured. Farmer has made an exhaustive study of the vascular system
in the young sporophyte of Angropteris (Farmer 3), and an extended study of An-
giopterts did not seem necessary, therefore, except for a study of the early stages to
determine the origin of the vascular bundles. All of the writers mentioned con-
cerned themselves almost exclusively with the fully developed bundles, beginning
their study at the base of the stem and working upward. No attempt was made to
follow out the development of the vascular bundles from the meristematic region
of the apex and proceeding downward, a method of study which we think would
have materially modified the conclusions drawn by these observers in regard to the
relation of the different parts of the vascular system.

In my studies as to the origin of the vascular system in the young sporophyte
of the Marattiacee the course of the bundles has been carefully followed in series
of microtome sections, passing downward from the apical meristem to the base of
the sporophyte, where the axial primary bundle passes into the primary root. These
series of transverse sections were then compared carefully with series of longitudinal
sections of young plants of approximately the same age, and in this way a clear
conception was obtained of the arrangement of the vascular system within the stem
of the young sporophyte.

THE DEVELOPMENT OF THE VASCULAR SYSTEM IN DANAMA.

Especial attention has been given to the development of the vascular system in
Danea and Kaulfussia, as these have received less attention than Marattia and
Angiopteris, and moreover are probably more primitive forms whose structures have
departed less from the ancestral type than those of either Marattia or Angiopterts.

A longitudinal section of the young sporophyte of Danea jamatcensis at the
period when the root is just about to emerge is shown in fig. 121, 4. The root in
this species, as in D. simplic ifolia, described by Brebner, is the first organ to appear

THE OLDER SPOROPHYTE 161

outside the prothallium,; the cotyledon at this time is still very small and the lamina
is scarcely developed. The root apex does not show in the section figured and all
that can be seen is the upper portion of its stele, which joins the two young vascular
bundles that extend respectively into the cotyledon and the second leaf, which can
already be recognized. The greater part of the young sporophyte is made up of
large thin-walled cells. Figure 121, B, shows a median section of the young cotyledon
from this same embryo, which is strongly bent over the stem apex. It is possible
that the square terminal cell, which in the drawing has the nucleus indicated, is the
apical cell of the leaf, but this is not at all certain. The outer part of the cotyledon
is made up of large thin-walled cells like those which compose the bulk of the
sporophyte, but at its apex there is active cell division, and traversing the young
cotyledon and placed somewhat toward its inner side, can be seen the primary
vascular bundle, made up of elongated procambium cells. This bundle can be
easily followed down into the body of the sporophyte, where, as we have seen, it is

Fic. 145.

Transverse sections of a very young sporophyte of Danwa jamaicensis. 160.
A shows cotyledon apex; C, apices of the stem and second leaf; G shows root apex.

continued without interruption into the stele of the primary root. The stem apex,
which does not show in the figure, is in a slight depression close to the base of the
cotyledon and shows, as usual, a single deep apical cell. Nearly opposite the cotyledon
is the beginning of the second leaf (/*); this is shown in median section in fig.121, B.
The group of narrow columnar cells that compose its apex does not show a recog-
nizable single initial cell. A short distance below its apex, the procambium of its
vascular bundle becomes differentiated and is continued downward until it joins
the bundle from the cotyledon. The tissue arising above the junction of these two
bundles and continuing upward into the apex of the stem is composed of absolutely
undifferentiated parenchyma and there is no evidence at all of any stelar tissue in
the stem above the junction of these two primary leaf traces; indeed, the stem apex
lies decidedly on one side of the plane which traverses the vascular bundles of the
two leaves. Fig. 145 shows a number of cross-sections from a series taken from a
large embryo of Danewa jamaicensis, before the emergence of the cotyledon (4),
11

162 THE MARATTIALES

whose apex is still undivided. C shows the apices of the stem and second leaf, the
former being shown on a larger scale in G. ‘The section of the cotyledonary bundle,
lying to the right of the stem apex, is plainly evident in section C. D shows the
separated bundles of the cotyledon and very young second leaf, which lower down
unite into a single strand.

Whether we can properly speak of a stem at all in connection with the tissues
composing the central region of the young sporophyte is questionable. It is per-
fectly evident that this central region is composed partly of tissue belonging to the
base of the cotyledon, which is in no sense to be looked upon as an adjunct of the

Fic. 146.—Ten transverse sections of a young sporophyte of Danaea jamaicensis.

A-C. Three sections near the stem apex, which is shown in B- _F-J. Show the condition of the vascular strand in the lower

and more highly magnified in D. Fig. C is reversed in region of the sporophyte.
Position with reference to A. H, I. Are in the transition region.
E. The central region of C. J. Shows the root stele. X200.

stem, and partly of the root base; the two structures, i. e., the bases of the root and
the cotyledon, merge insensibly into each other. To this tissue, derived from the
root and the cotyledon, must be added a large amount of superficial tissue derived
originally from the foot of the embryo. In speaking of the axis of the young sporo-
phyte as a “‘stem”’ it must therefore be borne in mind that this stem is really a
composite structure, partly leaf, partly root, and partly foot.

Fig. 138, 4 and B, shows two longitudinal sections of an older stage after the
emergence of the cotyledon. 4 passes through the stem apex and it is evident
that there is no vascular bundle extending into the stem. The tracheary tissue is
now well developed in the leaf trace. B shows the trace from the second leaf
at its point of junction with the bundle from the cotyledon. In fig. 138, C is a similar

THE OLDER SPOROPHYTE 163

stage to that shown in J, but cut at right angles to it, so as to show the continuity
of the bundles of the cotyledon and primary root, which together constitute the prima-
ry axial vascular bundle of the sporophyte, as they do in Ophioglossum moluccanum.

The similarity of such a section as that figured to the similar stage in O. moluccanum
is sufficiently obvious. ‘The stem apex is shown in fig. 140, 4, and the rudiment of
the second leaf is shown in fig. 140, B.

Figure 146 shows ten transverse sections from a series made from a young sporo-
phyte Dy jamaicensis of almost exactly the same age as that shown in fig. 138, B.
A is cut above the level of the stem apex and passes through the cotyledon ‘and apex
of the second leaf. The arrangement of the cells at the apex of the latter suggests
the possibility of a single apical cell. The base of the petiole of the cotyledon is
much flattened and is made up of large, thin-walled parenchyma with no traces of
tannin cells or mucilage ducts. “The vascular bundle is oval in outline and decidedly
collateral in structure. There is no recognizable endodermis, and I shall not
attempt to say whether the cells immediately surrounding the bundle should be
spoken of as endodermis or pericycle. Except for two small tracheids on the inner
side of the bundle the vascular bundle is composed of delicate tissue, apparently
parenchyma, but some of the larger elements undoubtedly represent sieve tubes.
Brebner states that the sieve tubes in D. simplicifolia (Brebner 3, page 524) do not
show clearly in sections mounted in Canada balsam, but when examined in other
media they show thick, glistening walls and pitted areas. This point was not further
examined in the species under consideration, but would probably agree with the
observations made by Brebner upon D. simplicifolia.

Section B passes through.the stem apex, whose apical cell is shown on a larger
scale in D. The cotyledon trace in this section shows three tracheids. In D the
section is made a short distance below the stem apex and shows the second leaf trace
bending in to join the trace from the cotyledon. The central part of the section is
shown more enlarged in &, and it is perfectly clear that the region immediately
below the apex and lying between two leaf bases shows nothing which can be
interpreted as a cauline stele. F and G show sections taken still further down,
illustrating the coalescence of the two leaf traces to form the single axial stele. In
G there is seen the first tracheid belonging to the leaf trace from the second leaf,
and in Hf the central bundle is complete and there are seen the two xylem masses
corresponding respectively to the two leaf traces. One of these, belonging to the
primary leaf trace, is more developed than the other one. The larger xylem mass
in this case had five tracheids and the smaller one three. / and / are transitional
stages between the bundle of the cotyledon and the root, and, proceeding down-
wards the bundle becomes somewhat smaller and there is a reduction in the number
of tracheids, which, however, are plainly seen to be continuous in their development
with the two xylem masses in the central bundle of the stem, formed by the j junction
of the two primary leaf traces, which maintain their identity until they merge into
the two xylem masses of the diarch root. Within the root itself the endodermis
surrounding the bundle is very conspicuous. The cells making up the endodermis
are of large size and the characteristic markings upon their radial walls are very
easily seen. The limits of the endodermis become much less clear in the transi-
tional region, and higher up it is difficult to make out a clearly defined endodermis.
Brebner “figures a very irregular endodermis in the stem of D. simplicifolia, and
perhaps we may assume that a proper endodermis is present also in the young stem
of D. jamaicensis, but it is certainly very inconspicuous, to say the least, in the central
region of the young sporophyte, in strong contrast to the very conspicuous endo-
dermis in the root. Farmer (Farmer 3) was able by treatment with sulphuric acid

164 THE MARATTIALES

to demonstrate an external endodermis in the stem bundles of Angiopterts, M arattia,
and Kaulfussia, and presumably similar treatment would show its presence in the
young stem of Danaea.

It is evident that we can not speak of the young sporophyte in Danaea samat-
censis as possessing in its early stage a“ protostele,” or “haplostele,” to use Brebner’s
terminology, unless we choose to call the single leaf trace of the cotyledon a protostele.
Just so soon as the two first leaf traces unite, the axial vascular bundle of the young
sporophyte has two quite independent xylems.

Figure 147 is a longitudinal section of a sporophyte of D. elliptica, slightly
older than that of D. jamarcensis shown in fig. 138. The second leaf (/*) had already
begun to develop the lamina, whose apex was forked so that there were two veins
present. A longitudinal section of one of the two leaf lobes is shown in D. The
stem apex closely resembles that of D. jamarcensis, the apical cell having much the
same form and size. The stem apex does not lie in the same plane as the leaf traces

Fic. 147-—Danaea elliptica.

A. Nearly median section of a young sporophyte, showing C. Median section of second leaf. X35.
origin of second root, r*. X35. D. Apex of second leaf. X150.
B. Central region. X150. E. Stem apex. X150.

and hence does not show in the figure, which is a section passing directly through
the leaf traces. This plant showed very clearly the very earliest stage of the second
root (fig. 147, 4,7°). The apical cell of the young root is cut out from one of the cells
of the parenchyma below the stem apex, lying almost exactly half-way between the
two primary leaf traces. Only a single segment had been cut off from the apical
cell in this case and both the apical cell and this primary segment were easily dis-
tinguished from the surrounding tissue by their denser contents. There is nothing
to indicate that the cell which had assumed the function of the root initial was in
any way essentially different from the neighboring cells. If it is an endodermal cell
there is no way of recognizing this, as the endodermis could not be recognized in
this part of the sporophyte. Figure 147, B, shows an enlarged view of this young
root initial, lying above the junction of the two primary leaf traces. Conspicuous
reticulate tracheids with pointed ends are present in the trace from the cotyledon,
but as yet no permanent tissue has been developed in the bundle from the second leaf.

THE OLDER SPOROPHYTE 165

A somewhat older sporophyte from D. jamaicensis is shown in fig. 148. In
this plant the third leaf was plainly visible and the second root had developed into
a short conical body which was pushing its way through the tissues between the

Fic. 148.

A, B, C. Three sections of a sporophyte of Danza jamaicensis with three leaves
PD. Median section of the second leaf. In C is shown the second root,r*. X20.

insertion of the first and second leaves. By this time tracheary tissue has developed
in the bundle from the second leaf, and now for the first time we note the presence
of large tannin cells in the neighborhood of the vascular bundles. Three of these
are shown in fig. 149, lying next the bundle of the second leaf. The irregular ring

Fic. 149.

A, the stem apex; B, apex of the second root of the sporophyte shown in fig. 148. 150.
The shaded cells in A are tannin sacs.

of narrow cells shown in the figure and lying below the apical meristem marks the
point of insertion of the second root. Figure 149, B, shows a nearly median section
of the apex of this second root. The apical cell is nearly oblong in form and the
lateral segments are very large and periclinal segments which contribute to the root

166 THE MARATTIALES

cap are cut off from them. The outer cells of the root cap are very much enlarged
and there is an evident space between the root and the surrounding tissues. The
trace from the third leaf joins that of the second one close to its union with the
bundle from the cotyledon (fig. 148, B).

In fig. 150 are shown nine cross-sections from a series made from a plant of D.
jamaicensts, in which four leaves were evident. A microscopic examination of the
stem apex showed, however, that a fifth leaf was also present, which stood nearly
directly opposite the cotyledon. 4 shows sections only of leaves 3 and 4, the latter
having the stipules conspicuous, while these are absent or scarcely developed at all
on the first three leaves, at least in the specimen in question. Between the leaves
are seen sections of the numerous scales which beset the surface of the young leaves.
B is taken somewhat lower down and includes a section of leaf 5. C passes through
the stem apex and shows clearly the spiral arrangements of the first five leaves,
each of which has in its petiole a single concentric bundle which becomes larger in

biG. 150.—D. jamaicensis.

Series of transverse sections of a young sporophyte, with three fully-developed leaves and two younger ones. X20.
Section C passes through the stem apex. Roman figures indicate successive leaves.

each successive leaf, with a corresponding increase in the development of the xylem.
As the sections are examined, farther and farther down in the stem (D to F), one
can see very clearly the way in which the single bundle in the lower part of the
stem owes its origin to the coalescence of the leaf traces. Proceeding downward
the traces of leaves 4 and 5 are seen to approach gradually and finally to become
completely coalescent; and still further down (F) the leaf trace from 3 joins that
from 4, and a single bundle results, crescent-form in section, but showing clearly its
compound nature. The three xylems never become entirely confluent.

THE OLDER SPOROPHYTE 167

For a long time sections of the stem show this single central bundle of crescentic
form, at first derived from the coalescence of the third, fourth, and fifth leaf traces,
but continued upward in the same form and added to by the addition of the traces
from the subsequent leaves. This crescentic stele, which, for convenience may
be spoken of as the stele of the stem, is entirely of foliar origin. “The crescent never
becomes completely closed and its opening in the earlier stages of development can
not be properly called a foliar gap. The parenchyma which is inclosed within its
curve belongs from the first to the ground tissue and is not part of the stele. Some
of the surrounding cells show traces of the typical endodermal markings and it is
perhaps safe to say that the stele is bounded by an endodermis, as Farmer states is
the case in Angiopterts and Brebner in D. simplicifolia. The limits of the endo-
dermis, however, especially upon the concave side of the stele, are very vague. The
stele, after the complete fusion of the three leaf traces, may perhaps best be described

Fic. 151.

Four longitudinal sections of a young sporophyte of Dana elliptica. X18. The fourth leaf, /*, has the stipules well developed;
r*, sections of the third root. m, mucilage duct; st, stipules.

as concentric in structure, with phloem developed all around the xylem, but there
are probably traces of phloem also between the three xylems which represent the
three confluent leaf traces.

In the older portions of the stem the bundles become still more completely
fused and the compound bundle is oval in outline, but still shows plainly the three
xylems of its constituent leaf traces (fg. 150, G). In this region the endodermis
is rather better developed than it is higher up, but its limits are still rather vague.
At this level the traces of the leaves, 1 and 2, are still free, but have approached
nearer to the central bundle than is the case higher up.

Still lower down, the trace from the second leaf joins the bundle formed from
the later leaf traces, which no longer clearly shows the separate Ens but ap-
proaches the condition which has been described as “ protostelic,”’ or “‘haplostelic,”
using Brebner’s terminology. ‘The xylem elements, however, do not form a solid

168 THE MARATTIALES

core, but are more or less scattered, with thin-walled elements between. After
fusion of the second leaf trace with this is complete, the section of the stem shows
only two bundles, representing the two first leaf traces, and finally (fg. 150, H and /)
the section of the stem shows the condition already described for the sporophyte
with but two leaves. These finally merge into a single primary axial bundle (/),
which, followed downward, merges imperceptibly into the stele of the primary root.
Near the middle of these lower sections can be seen a section of the second root,
which pursues a downward course through the cortical tissue for a very long distance,
but finally emerges and grows downward, side by side with the primary root. The
third root (fig. 150, G, r’) emerges much higher up and breaks through the cortex
at about the level of the junction of the three youngest leaf traces.

Fig. 153 shows the details of the central tissue from the same sporophyte as
that just described. 4 passes through the stem apex and shows the apical cell cut
somewhat obliquely, and near it the section of the trace from the fifth leaf. D is a
section of the fourth leaf trace from the same level. “This shows but two tracheids
at a point near the inner limits of the bundle, while on the outer side there is a con-
spicuous curved line of protophloem cells. B is a section taken somewhat lower
down and shows the bending in of the leaf trace as it descends into the stem. ‘This
is sull more marked in the fifth leaf trace, which, at this level, has a crescentic form,

A. Apex of fifth leaf from sporophyte shown in fig. 151. 150.
B. Stem apex of same.
C. Base of third root, showing triarch bundle and ring of sclerenchyma in cortex. Xgo.

but no permanent elements yet developed. It is probable that a portion of this
crescentic mass of procambium represents the sixth leaf trace. The fourth leaf
trace at this point shows three tracheids which are decidedly larger than those
higher up, and still lower down the tracheids increase still more in size and several
tannin cells can be seen in contact with them. The section of the fourth leaf trace
is connected with the large but undifferentiated trace of the fifth leaf by an isthmus of
procambium cells, so that the sections of the two bundles form the crescent-shaped
section, similar to that seen lower down (fig. 153, C). The tracheary elements of the
fused portion of the fourth leaf trace are noticeably larger again than those in the
free portion of the leaf trace. We now notice, for the first time, traces of the mucilage
ducts which afterwards become so conspicuous in the stem. These first appear in
section as rounded cells (m), and it is evident, as Farmer has shown in Angiopterts,
that the earliest mucilage canals are of lysigenous origin, i. e., they are formed bya

THE OLDER SPOROPHYTE 169

fusion of cells and not by a splitting apart of the cells and the development of
secreting cells about this intercellular space. In his earlier paper Brebner states
that the mucilage ducts are schizogenous, but in his later paper he admits that they
may be of lysigenous origin, which certainly is the case in the species of Danea
described here.

The details of the older central bundles of the sections F and G, fig. 150, are
shown in fig. 153, E, F,; the shaded cells in C are tannin cells.

Figure 151 shows longitudinal sections of a young sporophyte of D. elliptica,
of about the same age as the sporophyte which has just been described. This also
shows three fully developed leaves, while the fourth and fifth leaves are well advanced.

jo

Fic. 153.—Details of the vascular system of sporophyte shown in fig. 150.

A. Passes through the stem apex; B and C, lower down, showing the fourth and fifth leaf traces. X150.
D. A single leaf trace. X150. E,F. Vascular bundles from the lower part of the stem. m, m, young mucilage ducts.

The central bundle of the stem formed by the junction of the three first leaf traces
is now conspicuous and forms a stout central strand, continuing downward into the
primary root (r'). 4 is a nearly median section, passing through the stem apex,
whose large and conspicuous apical cell is shown in fig. 152, B. The apex of the
fifth leaf is seen just above this and a more enlarged figure of this is shown in fig.
152, 4. The apex of the fifth leaf (which is here cut transversely) is occupied by a
small group of large cells, of which the central one may perhaps represent a single
initial cell. Below the stem apex, but separated from it by a considerable amount
of tissue, can be seen the bases of the leaf traces from the fourth and fifth leaves
respectively. ‘These are joining the central bundle of the stem near the junction

170 THE MARATTIALES

of the third leaf trace, and at this point there may be seen the base of the third root
(r’). Between the fourth and fifth leaf traces is present a section of the first mucilage
duct. B is a section some distance to one side of the apex, also passing through the
primary mucilage canal and the fourth root, which arises between the fourth and
fifth leaf traces. Figures C and D are sections on opposite sides of the stem apex
from B. The fourth leaf, with its conspicuous stipules (st), shows in these sections,
and the third root can also be seen. Fig. 152, C, is a more enlarged view of the
third root shown in fig. 151, D. The root is triarch and in the peripheral part of the
cortex there is visible a row of very conspicuous cells whose walls stain very strongly
with safranine and in section closely resemble large tracheary elements. A longitudinal
section of these cells, which are also conspicuous in the later roots (fig. 155), shows

that they are elongated sclerenchyma cells whose thick walls are conspicuously
pitted. Farmer (Farmer 3) observed similar cells in the roots of Angropteris.

Fic. 154.

Two sections of an older sporophyte of D. jenmani. X18. m, mucilage ducts; st, stipules of young leaf; r, young root.

Figures 154 and 155 show three longitudinal sections of a pretty well advanced
young sporophyte of D. jenmant. ‘The root (shown in the figure emerging at the
base) is probably the second root. The stem has already begun to assume a dorsi-
ventral form, and the basal part of the root, which is strongly curved, is cut away
and so does not show in these sections. ‘The earliest leaves are no longer recognizable
and it is impossible to determine just how many leaves have been formed. The
leaves first formed have the single trace characteristic of the first leaves in all of
the species, but the youngest leaves show that the leaf trace is double. In this sec-
tion (fig. 155, 4) is shown a very young leaf, cut through parallel to its surface
and showing clearly the stipules at its base and also the young vascular bundles.
Within the leaf are two bundles, which are seen to join at its base, but separate
again lower down, the two bundles thus forming two distinct traces in the stem. In
fig. 154, B, the section passes through the youngest root, which is seen to have its
stele joined to one of the leaf traces from the youngest leaf. Several conspicuous
mucilage ducts are now present in the stem near the vascular bundles; these are

THE OLDER SPOROPHYTE 171

formed of rows of large cells which become more or less fused together and their
contents, composed of a dense granular mucilage, stain very strongly, either with
safranine or with Bismarck brown, which were the principal stains used in preparing
the sections. Numerous tannin cells are also present, scattered irregularly through
the cortical tissue and also in the vascular bundles.

Figure 155, B, is a median section through the base of one of the later roots,
showing i its connection with the corresponding bundle in the stem. The elongated
cells (sc) are the cortical sclerenchyma cells already referred to. “These are shown
on a larger scale in C and D, where the conspicuous pitted walls can be seen.
The shaded cells in the figure are tannin cells.

Figure 156 shows cross-sections taken at different heights from a sporophyte of
D. jenmanz, a plant of about the same age as that which was shown in the preceding
series of longitudinal sections. Sections made near the apical region, 4, B, and C,

Fic. 155.

Another section of specimen shown in fig. 154.
Base of a root showing sclerenchyma, sc, in cortex. X40.
Sclerenchyma cells, showing pitted walls. 320.

. Surface view, showing pits.

vowD>

show two pretty well advanced leaves and the first trace of a third, the apex of which
is indicated in C and FE. Unlike the earlier leaves with their single leaf trace, these
later leaves, as we have seen, have the petiole traversed by two vascular bundles
whose sections are plainly visible. ‘These, as we have remarked from a study of the
longitudinal sections, fuse into one near the base of the leaf (4), and two small
bundles are also present on either side, belonging to the stipules. As the sections
are followed downward, the main bundle is found to divide into the double leaf trace
entering the stem, and the two small stipule bundles become united with these, so
that within the stem, at about the level of the stem apex, two distinct bundles are
seen, corresponding to each leaf. The leaves are now arranged in two series,
indicating that the dorsiventral character of the stem in this species is established
and the youngest leaf lies almost opposite the next youngest one, whose leaf traces
can be seen. E shows the stem apex with the apical cell, x, and the youngest leaf

rudiment, /.

172 THE MARATTIALES

Below the level of the stem apex, the stele of the axis closely resembles that
already described from the somewhat younger plant and forms a somewhat irregular
crescent, evidently composed of two portions which are joined on the side facing the
two leaf traces from the oldest leaf which shows in this section. The opening of the
crescent at this level is turned away from the leaf. No permanent elements are
present in the central stele as yet. Following this downward, the crescent is seen
to open on the side next the two oldest leaf traces and there is thus formed a foliar
gap, while on the opposite side the space becomes closed. In section D, which
is taken lower down, the position of the section of the central stele is reversed. At

ca

Fic. 156.

A-D. Four transverse sections of a young sporophyte of D. jenmani. X20. Section C shows stem apex.
E. The apical meristem with apical cell of stem, x, and a leaf initial, /. 180.
F-I. Four sections from the same series, but taken lower down. X20. Figs. F, G, show fusion of double leaf trace with central
stele. m, mucilage ducts. Between the mucilage ducts in G can be seen the small commissural strand.

this point the section of the central stele forms a crescent of tissue, most of which
has not passed beyond the procambial stage. This crescent-shaped mass is evi-
dently composed of two parts and represents mainly the basal undivided bundles
of the two youngest leaves. Tracheary tissue has begun to develop in the older of
these two masses. Occupying the space within this crescentic stele are three young
mucilage canals, but none are yet developed in the cortical tissue of the stem.
Within this central space there can also be seen the section of a small isolated group

io)

THE OLDER SPOROPHYTE 17

of procambial cells. This is the single axial stele or commissural strand which had
not yet begun to develop in the plant with five leaves. The older leaf base, shown in
this section, has a single large vascular bundle, crescent-shaped in outline and con-
centric in structure, and there are also seen the two small concentric bundles belong-
ing to the stipules.

All the leaf traces in the older leaves are concentric in structure, with well-
developed internal phloem, and thus differ from the collateral traces of the earliest
leaves. This concentric structure of the bundle is already well marked in the fourth
leaf, where, however, the protophloem is mainly developed upon the outer side. F
shows the arrangement of the bundles in a section somewhat further down. ‘The
two strands from the oldest of the three leaves seen in the apex have joined the horns
of the crescentic central bundle, which still shows clearly its dual nature. In the
younger of the two portions of these sections the first tracheids have just appeared
near the free end, while in the older half a line of tracheids extends nearly through
the whole of the center. The mucilage ducts at this level are much larger and their
cells have become confluent. Cases to the large mucilage canal can abe seen the

Fic. 157-

A. Section of an older stem of Dana jenmans, showing cortical mucilage ducts, m, and central or
commissural strand, c. /t, leaf trace. r, root. 20.
B. Shows a section higher up, with free leaf traces and commissural strand.

section of the axial vascular strand, which somewhat higher up turns outward and
becomes fused with the inner face of the crescentic central stele. “The leaf traces
soon become completely merged with the broad crescentic stele and their limits
can no longer be recognized. The foliar gap gradually closes up and the two por-
tions of ae crescent separate at a point opposite so as to form a leaf gap, nearly
opposite the first one; but I have seen no cases where a section of the central stele
appears as an unbroken ring, although it is possible that this might occur for a
brief period. Much the same condition of things is seen lower down and it 1s clear
that in all cases, after the double leaf trace has been developed, one bundle fuses
with an older and one with a younger leaf trace. The axial bundle shows a central
mass of tracheary tissue, and in Some: older stages an endodermis 1s pretty well
developed. Finally this bundle can be traced dow nward to where it connects with
the main stele, composed of the united leaf traces. The main stele gradually passes
down into the base of the stem, where it shows the structure already described for
the younger sporophyte.

In older sporophytes the crescentic central stele becomes broken up permanently
into two elongated masses when seen in section (fig. 157), but the junction of the

174 THE MARATTIALES

leaf traces with these takes place exactly as in the younger plant. Fig. 157, B, shows
the separate leaf traces and the free axial strand, while in 4 the leaf traces are
becoming fused with the broad central strands and the axial strand is also anastomos-
ing with one of the latter. This has taken place at the point of junction with a
root. While in the younger sporophyte the mucilage ducts are confined to the central
region, in the older plant they occur also in the peripheral region of the stem (fig.
157, m). he details of the vascular bundles are shown in figs. 158 and 159.

Fic. 158.—Details of vascular bundles from sections shown in fig. 156.

A and B are the ends of the crescentic bundle shown in fig. 156, D ; C, is a leaf trace and D part of an older bundle. 150.

To recapitulate: The vascular system in the young sporophyte of Danwa
begins as a single axial strand, which is continuous through the cotyledon and root.
Ata very early period a second vascular bundle or stele is formed in the second leaf
connecting with the primary strand, and this is followed by a similar single strand
or stele in each succeeding leaf, up to about the seventh. Up to this time, except
for the steles of the secondary roots, the whole vascular system is built up of united

Fic. 159.

A, part of central stele; B, the commissural bundle from a young sporophyte of Danaa jenmant. , 150.

leaf traces and there is no cauline bundle in the strict sense of the word, although
we may speak of the bundle, or stele of the stem, as soon as there is a solid central
strand formed below the junction of the earlier leaf traces. This primary stele
never has the form of a true protostele, however, as the xylems belonging to the
separate leaf traces can be recognized and the compound nature of this central
bundle is unmistakable.

THE OLDER SPOROPHYTE 175

At a later stage, probably about the time that the seventh leaf is formed, there
arises the single axial (commissural) strand, which is cauline in its origin and which,
as Brebner has stated for D. simplicifolra, is the only strictly cauline portion of the
vascular system of the stem. This can first be seen at about the same time that the
first double leaf trace appears.

The development of the vascular system was not traced further, as it has already
been adequately described by Kuhn (Kuhn 2), and except for the increased number
of leaf trace and commissural strands the vascular system is essentially the same
in a young plant like that shown in fig. 157 as it is in the adult sporophyte.

Brebner’s account of the development of the young sporophyte in Danea
simplicifolra agrees essentially with my own studies of D. elliptica, D. jenmani, and
D. jamatcensts. He failed, however, to get successful sections of the transition
region between the root nied the cotyledon, or, as he puts it, ““ between the root and
stem,” and his statements that the central bundle begins as a “‘haplostele,” i. e.,
a protostele, is not borne out by my studies on the other species. Moreover, his
statement that “in this way the somewhat irregular adelosiphonic dictyostele of
Danea is established now by a process which is, to all intents and purposes, a
branching of the haplostele, due to the departure of the leaf traces of closely set,
spirally arranged leaves,’ might better be stated, “the dictyostele arises by a process
which is essentially the ficion of the leaf traces of closely set, not necessarily spirally
arranged leaves.” He fully recognized the important part which the leaf traces
play in the building up of the dictyostele of the stem, but he did not apparently
recognize these as the sole factors in the development of the dictyostele of the older
stem. He does, however, specifically state that the axial or commissural strand is
the only part of the vascular system which is strictly of cauline origin.

THE ADULT SPOROPHYTE OF DANZA.

The anatomy of what was supposed to be the sporophyte of Danwa was first
described by Holle (Holle 2), but the later investigations of Kuhn showed that the
plant investigated by Holle could not have been a Danea, nor could it even have
belonged to the Marattiacez, since Holle describes the rhizome as developing a
sheath of sclerenchyma, a condition of things which has not been found to exist
in any Marattiacee. Kuhn’s account is very far from complete and the description
of the sporophyte given by Brebner (Brebner 3) ‘for D. stmplicifolia does not deal
with the adult sporophyte. The account given) here is based mainly upon a study
of D. jamaicensis and D. elliptica, but an investigation of certain points was also
made in D. jenmani. The rhizome in D. jamatcensis and D. jenmani is a markedly
dorsiventral one. ‘These two species are a good deal alike, but are readily dis-
tinguished by the difference in the form of the leaves. In the former the leaves are
rather larger and have more numerous pinne, while the terminal pinna is developed.
D. jenmani has somewhat smaller leaves with from seven to nine pairs of leaflets,
and the leaves are abruptly pinnate, the terminal pinna not being developed (plate 9,
Ay fig. 1).

"Phe leaves are arranged very much as they are in Helminthostachys or in
Ophioglossum pendulum, the fleshy leaf base being provided with two very conspic-
uous stipules which are developed very early in “the life of the sporophyte. ‘The
exact number of roots corresponding to a leaf is not easy to make out, but there are
at least two, and it is quite possible that the number may sometimes be greater.
These roots branch freely, especially toward the tips.

D. elliptica (plate 10) is a good deal larger than the other species and the stout
rhizome, which, including the persistent eae bases, has a diameter of 3 centimeters

176 THE MARATTIALES

or more, is upright, the leaves being spirally arranged as they are in Marattia and
Angiopteris. The petioles in this species are characterized by curious enlargements
or nodes, which may occur in the other species also, but are much less prominent.
The leaves of D. elliptica reach a length of about 50 centimeters and the leaflets,
which are much larger than those in the other species, are less numerous, there being
usually about eleven. ‘The conspicuous nodose swellings seen in the petiole are
repeated on a smaller scale in the rachis at the base of each pair of leaflets. Sections
of the stems were examined in D. jamarcensis and D. elliptica, which, except for a
difference in size, agree closely in their structure. The ground tissue, as was first
pointed out by Kuhn, consists entirely of parenchyma, through which are scattered
many conspicuous tannin sacs which, in preserved material, appear to the naked eye
as numerous black specks. The section of the vascular cylinder looks very much
like that of the younger sporophytes already described, but the number of bundles
seen in the section is larger, and there is a group of several bundles instead of the
‘single medullary strand seen in the section of the younger stem. In a section from
a large specimen of D. elliptica in which the rhizome, including the old leaf bases,

A. Section of petiole of fourth leaf of Danwa jamatcensis. 40.
B. Leaf trace.
C. Bundle of petiole. 180.

was about 3 centimeters in diameter, the outer ring of bundles contained thirteen,
while within this was a smaller circle composed of five medullary bundles, three
large ones and two smaller ones. In a similar section of a medium-sized section of
D. yamaicensts, in which the rhizome was about half the size of that in D. elliptica,
there were nine bundles in the outer ring and four in the middle, two large ones and
two small ones. In this section the junction of a root was cut through and the root
stele was seen to be applied by its broad base to one of the larger of the medullary
bundles (fg. 161, 4).

The relation of this central group of bundles in the stem to the primary medullary
strand was not investigated. Brebner has shown that in the later stages of the young
sporophyte in D. simplrcifolia the original medullary strand—which, as we have seen,
is really the only part of the vascular system which is strictly of cauline origin—
fuses at certain points with the bundles of the outer ring, and at this point of fusion
there may be a branching so that a section above this shows two of these medullary
bundles. Whether all of the central group of bundles seen in the stem of the adult

THE OLDER SPOROPHYTE WH

sporophyte in D. jamaicensis and D. elliptica are due to further branching of the
primary medullary strand, or whether some of them may be new bundles of cauline
origin, remains to be investigated.

The arrangement of the characteristic mucilage ducts is the same in the two species
studied. There is a ring of these in the outer region of the cortex and a second group
in the central region, these central ones usually being close to the vascular bundles.

Fic. 161.

A. Section of adult rhizome of Danwa jamaticensts. X2.25
B. Section of rhizome of D. elliptica. X1.5.
The mucilage ducts are not shown.

THE ANATOMY OF THE LEAF.

A section of the petiole of the adult leaf appears very much like a similar section
of the stem, except that there is developed in the cortical region, separated by several
rows of cells from the epidermis, a band of sclerenchyma, yellowish or brownish
in color, and very much indeed like that common in the typical ferns. Holle’s
statement that a similar mantle of sclerenchyma occurs in the stem was shown to
be an error, the result of his having investi-
gated a fern which was not a Danea.
There certainly was no trace of scleren-
chyma in any of the specimens I have
examined.

The distribution of the vascular bun-
dles in the petiole is very similar to that in
Helminthostachys, except that inside the
ring of bundles there is a single larger
central one, instead of the two small ones
which occur in Helminthostachys. All the
bundles are continued into the stem as
separate strands or there may be a certain
amount of anastomosing among them, as
there is in Ophioglossum pendulum, which
Danea resembles more in the character of its leaf traces than it does Helmin-
thostachys, where the bundles of the petiole are united into a single trace within
the cortex of the stem.

The distribution of the mucilage ducts in the petiole is very much like that of
the stem. There is a definite ring of these inside the zone of sclerenchyma and several
larger ones in the central region, near the vascular bundles. ‘The form and venation
of the leaf is essentially the same as in the younger sporophytes which have already
been described, and stomata are developed only upon the lower side, the epidermal
cells showing a strongly undulate outline, except for the series of narrow cells which

12

Fic. 162.—Apex of small root of Danza jenmant. 200.

178 THE MARATTIALES

immediately surround the stoma. A section of the lamina presents an appearance
very much like that of Helminthostachys. Below the upper epidermis is a well-
developed palisade layer, while below this the spongy mesophyll has the characteristic
intercellular spaces found in the leaves of most of the higher plants. Danea tricho-
manoides,a very small species from Peru, has delicate membranaceous leaves, which
probably would show a much simpler structure than that of the coriaceous leaves
of the larger species. D. sintensis, a species from Porto Rico, which is in the herba-
rium of the British Museum, has adventitious buds developed at the leaf tip.

d
I

Ps

Lad

Fic. 163.
A, B. Two longitudinal sections of a young sporophyte of Kaulfussia. 1*,1°, second
and third leaves; r?, second root. X20.
C. Stem apex. 180. D. Apex of third leaf. 180.

THE APICAL GROWTH OF THE ROOTS.

The earlier roots grow from a single initial cell, but this is later replaced by a
group of similar initials which, in the large roots, are very much like those described
for the root apex of Aniopiiat (Koch 1). Figure 162 shows a section of a root
from the young sporophyte which is somewhat transitional in character between the
form with a single definite initial cell and the larger root with its group of initials.
The cell x, which is very much like the apical cell of the primary root, may perhaps
still be considered as the single apical cell, but the adjacent segments are almost
equal in size to this, and it ts clear that they contribute to the plerome cylinder of
the root as well as to the cortex and the root cap.

In sections of large roots taken from the adult sporophyte, there is found at the
growing point not a single initial cell, but a group of apparently similar initial cells
somewhat wedge- shaped i in longitudinal section and arranged in a radiating fashion.
No single one of these can be clearly recognized as a primary initial cell. These
cells divide at intervals by longitudinal walls and from the bases additions are made

THE OLDER SPOROPHYTE 179

to the plerome cylinder, while from the outer cells of the meristem group arise the
new cells for the root cap. The outer segments cut off from the peripheral cells of
the apical group of cells undergo more rapid periclinal divisions than those nearer
the center and the cells thus formed contribute to the cortex of the root.

Unlike the roots of most of the Ophioglossacee, those of Danea branch
freely in a monopodial fashion. This is paralleled among the Ophioglossacee by
some of the larger species of Botrychtum, Helminthostachys, and Ophioglossum
pendulum. Kihn’s statement that the roots are unbranched is incorrect. The
branching of the roots was perhaps somewhat more frequent in D. jamaicensis
than in D. ell: ptica, but the latter species also shows numerous short lateral rootlets.
The root hairs are not conspicuous on these older roots, but are readily seen upon
the younger ones and are then found to be multicellular, as was first shown by
Brebner for D. simplicifolia. Sections of the larger roots were examined in these
two species and, while they agreed in the main, there were some slight differences.
In a large root of D. elliptica, about 2 millimeters in diameter, the outer portion was
occupied by about four rows of brownish thin-walled cells, very probably more or
less suberized. Within this was a ring of brownish sclerenchyma cells about three
cells in thickness, and between this and the exceedingly conspicuous endodermis was
a broad zone of parenchyma, the cells containing much starch. A short distance
outside of the endodermis was a ring of conspicuous mucilage ducts. There were
twelve xylem rays alternating with as many rays of phloem. These did not extend
to the middle of the stele, which was occupied by a pith of considerable size.
The roots of D. ;amatcensits were somewhat smaller and the main differences were:
first, the thicker layer of tissue outside the ring of sclerenchyma, which was much
less developed than in D. elliptica (in many places this ring was but one cell in
thickness and very seldom more than two cells); second, the mucilage ducts were
relatively very much larger; third, there were but nine xylem masses instead of the
twelve in the root of D. elliptica.

The endophyte, which is usually found in the primary roots of all the Marat-
tiacez is generally wanting from the larger roots of the adult sporophyte.

THE SPOROPHYTE OF KAULFUSSIA.

The development of the young sporophyte in Kaulfussia resembles that of
Danea in most respects, but from the first it is markedly dorsiventral, like the
sporophyte of Helminthostachys. The cotyledon, while not provided with the char-
acteristic free stipules of the later leaves, still has its base connected with a ridge
which extends around the stem apex and youngest leaves, which thus lie in a cavity
at the base of the cotyledon in much the same way that the stem apex is situated in the
young sporophyte of Ophioglossum; but the sheath in Kaulfussia forms a shallow
open cup, instead of the closed conical sheath found in Ophioglossum. This stipular
sheath seems to be in all respects similar in its origin to that found in Ophioglossum.

The second leaf lies nearly opposite the first and the third next to the first,
and so on, the distichous arrangement being evident from the beginning. We have
already pointed out that in the very young sporophyte the vascular bundle from the
cotyledon is continued directly into that of the root and that the bundle from the
second leaf joins this common bundle, as shown in fig. 163. These primary bundles
run on one side of the apical meristem, which, as in Danea, is of very limited extent
and does not contribute at all to these bundles.

The apical cell of the young sporophyte, up to the oldest stages that were in-
vestigated, is very much like that of the very young plant and is broader than that
of Danea, more resembling both in cross and longitudinal sections the apical cell

180 THE MARATTIALES

of Ophioglossum. he young leaves arise right and left in succession on either side
of the stem apex, and from a very early period are strongly bent over, showing the
characteristic circinate vernation of the Marattiacea. Sections made through the
apex of the young leaf show that it has at first a definite apical cell a good deal like
that which is found in the stem apex, and although no satisfactory cross-sections of
this apical cell were found, there seems to be no question that there is present a
single definite initial cell which probably has much the same form as that of the stem
apex. The young leaf, at this stage, has the dorsal region strongly convex and
composed of large parenchyma cells. “The apex is bent over forward and downward.

Fic. 164.—Series of transverse sections from a young sporophyte of Kaulfussia, showing the coalescence of the two primary
leaf traces. /*, second leaf; /*, third leaf; r*, second root. X40.
D. Stem apex more enlarged.
F-H. Central region of the sections. The fusion is complete in H. The shaded area is a mucilage duct.

The tissues of the apex and the adjacent region are composed of small, actively
dividing cells. The young vascular bundle can be clearly seen extending nearly to
the apex and continuing downward into the stem until it joins the bundle from the
next older leaf.

The second root arises at about the same time that the third leaf is recognizable
and apparently its origin is exactly the same as it is in Danaea. Its stele joins the
central bundle of the stem near its junction with the third leaf trace. The young
leaves, like those in Dana, are sparingly covered with hairs and scales, but these
scales do not have the peltate form found in Dana, being usually short rows of
stout cells; or the hair may have its base composed of an oblong mass of cells
attached by a narrow stalk and having its apex drawn out into a slender filament
composed of two or three elongated cells. The terminal cells of these hairs usually
stain very strongly, indicating that they contain tannin.

The young bl candi are relatively stouter than in Danaea, but otherwise resemble
them closely. ‘In the young sporophyte, up to the time of the formation of the third
leaf, there may be no trace of the mucilage ducts, although these may be developed

THE OLDER SPOROPHYTE 181

at an earlier period. ‘The mucilage ducts throughout the life of the sporophyte
are less conspicuous in Kaulfuss:a than in Danea.

A section taken at the level of the stem apex in the very young sporophyte
(fig. 137) presents an appearance not unlike that found in the bud in Ophioglossum.
The base of the cotyledon extends around the stem apex, so that in the section the
stem apex and the second leaf are inclosed in this cavity formed by the stipular
sheath of the cotyledon. Higher up, the base of the cotyledon becomes free from the
second leaf, but this takes place earlier on one side than on the other.

The development of the vascular system in the stem is exactly as it is in Danea.
The stem apex in the young sporophyte takes no part in the development of the
vascular bundles, the stele in the stem being made up entirely of the united leaf
traces. In the specimen figured (fig. 164), in which the second leaf was still quite
young, the bundle from the cotyledon passes downward into the stem and continues
its downward course until it joins the second leaf trace. The resulting solid stele
at first shows the two separated xylems of the component leaf traces which lower
down merge into a single thick band of xylem completely surrounded by the phloem

Fic. 165.—Three longitudinal sections of a young sporophyte of Kau/fussta, with three leaves. X25.

(fig. 164, E-H). This stage corresponds to Brebner’s “haplostele” in Danea sim-
plicifolia. This condition merges insensibly into the primary root with its diarch
bundle, the two xylems in the younger part of the root being quite separate, but
forming a single band at the base of the transitional region, between the root and
the bundle in the stem. The bundle of the root shows a conspicuous endodermis
which becomes less and less evident in the transitional region, although it prob-
ably never quite disappears. The primary root usually shows the presence of an
endophytic fungus like that occurring in the prothallium and in the primary root
of most of the Ophioglossacece.

Fig. 166 shows cross-sections of a young sporophyte in which the fifth leaf is still
quite small, but with its trace showing the first tracheary tissue. This fifth leaf trace
unites below with the trace from the fourth leaf and forms a single bundle, with
the xylems separate. ‘he xylem from the fourth leaf above its junction with the fifth
leaf trace forms at first a continuous band which divides into two parts, one of which
unites with the xylem from the fifth leaf trace, while the other remains distinct.
This separation of the xylem in the fourth leaf trace is the first indication of the for-
mation of the double leaf trace, such as we shall find occurs in the later leaves.

182 THE MARATTIALES

The separated xylems become joined lower down into a single transverse plate, just
before the junction of the strand with the trace from the third leaf (fig. 166, /7),
with which it joins in the same way and is continued downward to the junction with
the strand arising from the fusion of the second leaf trace with the cotyledon. Above
the junction of the first and second leaves, the stele of the second root, which grows
vertically downward, joins the stele formed by the junction of the three youngest
leaf traces.

Above the junction the section of the bundle is nearly circular in outline, the
large tracheids forming a broken group in the center of the bundle, quite like a

AG

\
|
Se |

\

“

A-C. Series of transverse sections from a sporophyte of Kaulfussia, of about same age as that shown in fig. 165.
D. Stem apex.

H-J. Three sections lower down.
K. Central vascular cylinder still lower down.

Fic. 166.

corresponding stage in Danaea. Some of the cells adjacent to the bundle show the
typical thickenings on the radial walls, indicating that they belong to the endodermis,
but the limits of the endodermis are extremely vague. In this plant two mucilage
ducts had developed in the fourth leaf, one on each side of the vascular bundle
(fig. 166, B, m).

The second root is stouter than the primary one and its bundle is triarch. The
mycorrhiza present in the first root could not be detected in the second root, but
possibly may be developed at a later stage. All of the roots are provided with root

THE OLDER SPOROPHYTE 183

hairs, which resemble those in Danea in being multicellular. In the larger roots
there may sometimes be five or six cells, each with a conspicuous nucleus, making
up these root hairs, and sometimes they show signs of branching at the apex.

It is evident that in Kaulfussia, up to the time that five leaves have developed,
the vascular system of the stem consists of a single axial strand, a sort of sympodium
formed by the completely united traces of the young leaves. ‘The xylem may appear
as a single mass at the points where fusion of the leaf traces is complete, but at most
points the individuality of the component strands is maintained, so far as the xylem
is concerned.

Figure 168 shows transverse sections from a much older sporophyte. The
section of the petiole still shows the single vascular bundle having near its inner face
a single large mucilage duct, which follows the leaf trace downward into the stem.
As the bundle from the leaf enters the stem it broadens, and there is a separation
of the xylems into two masses, first seen in the fourth leaf. In the specimen shown
here the earliest leaves were not sectioned, and, as it can not be stated exactly how
many leaves the young sporophyte had developed, it must therefore remain uncer-
tain which leaf first shows the completely divided leaf trace. In the specimen in
question the oldest leaf that showed had a single trace with two separate xylems,

while the next leaf had the leaf trace completely separated and resembling a corre-
sponding stage in Danaea (fig. 168, F). As the traces from the two leaves approach
preliminary to their fusion, the double leaf trace has its parts united again so that
the traces become single before they join. The leaf trace now forms a single bundle,
crescentic in section and very much like the single broad leaf trace from the earlier
leaf. The two traces come nearer and nearer and finally fuse on one side, so that
a section shows a single bundle almost circular in form, but broken on one side
(fig. 168, H). This break is finally closed up, and the section of the bundle is
completely circular and resembles very closely that of Botrychium or Helminthos-
tachys, except that phloem is developed inside the ring of xylem (fig. 168, K). A
similar condition may sometimes be found for a very Sort time in the young plant
of Danea also.

No certain evidence of an internal endodermis could be made out and the
external endodermis is also somewhat vague, although there is probably no question
of its presence. The outer phloem is bounded by. a fairly well-defined pericycle,
between which and the starch-filled cortical cells of the stem are two or three layers
of transparent cells, some of which presumably constitute the endodermis. The
endodermis is certainly present in the free leaf traces, although less conspicuous

184 THE MARATTIALES

than it is in the roots. In the upper region of the stem the leaf traces are further
apart, and as the number increases a cross-section of the stem shows a circle
of separate bundles closely resembling the arrangement in Ophioglossum. The
central “commissural” strand, which is found in the adult stem, had not developed
in any of the young sporophytes I examined and evidently arises much later in the
history of the sporophyte than it does in the other Marattiacew. In this respect,
as well as in the arrangement of the bundles themselves, Kaulfussia is more like

Fic. 168.

A, B. Two sections above level of stem apex of a young sporophyte of Kau/fussia of about same age as that shown in fig. 167.
C-J. Sections taken lower down from same series. m, mucilage ducts.
K. Central bundle of section J. X140.

L. Part of the bundle of section H, more enlarged. G,F, I, J, show only the central region of the sections.

Ophioglossum than it is like the other Marattiacee. In the intermediate condition
between the single solid stele found in the very young stem and the entirely separated
leaf traces of the older rhizome, there is a transitional condition with a “siphono-
stele,” very much as in Helminthostachys (fig. 168, K).

In one very young sporophyte there was found, in the cortex of the primary
root near its base, a large lacuna which recalled the similar lacuna found in the
first internode of Helminthostachys.

THE OLDER SPOROPHYTE 185

The young sporophyte of K aulfussra is almost completely destitute of the tannin
cells which are so conspicuous a feature in Dana, and these tannin cells are prac-
tically entirely absent from the sporophyte throughout its whole existence. In this
respect there is a marked resemblance to Ophioglossum. The mucilage ducts are
also somewhat less developed than in the other Marattiacea and are mainly con-
fined to the central part of the stem in proximity to the vascular bundles. At a late
period they may also appear in the cortical region. Their lysigenous origin is less
evident than in Danea and it is not impossible that they may sometimes be of
schizogenous origin, as Brebner states is often the case in Danea.

The structure of the vascular strands is very much like that of Danaea, as a
reference to the figures will show. There are developed slender, spirally-marked
protoxylem elements like those in Danea and which we have already seen occur
also among the Ophioglossacez, in Helminthostachys.

The stipules in the young plants of Kaulfussia are much less definite than they
are in Danea. A cross-section through the bases of the young leaves shows that
instead of the bases appearing free, each with its distinct stipules, the leaf is confluent
with the next one, one side being slightly extended and free. The leaf base thus
incloses the next younger leaf completely on one side, but leaves it free on the

Fic. 169.

A. Bundle from intermediate region of a very young sporophyte of Kaulfussia. 150.
B. Section of primary root. X150.
C. Section of bundle of second root. en, endodermis. X150.

other (fig. 168, B). In the later leaves the stipules become more conspicuous, but
they are always connected by a very conspicuous commissure in front (fig. 171, com)
so that a section of the young leaf base shows a space between the front of the petiole
and the stipular sheath. In short, the structure is very similar to the open stipular
sheath of Botrychtum virginianum and apparently arises in much the same way.

The structure of the adult sporophyte has been carefully investigated by Kuhn,
who pointed out that it is the simplest of the Marattiacee in the structure of the
stem (fig. 171, B). As in the young sporophyte, the stem shows in section a single
circle of vascular bundles, but there is in addition a single median strand within the
circle of bundles belonging to the dictyostele, and this bundle is presumably of
cauline origin, like the corresponding one in Danea.

The whole vascular skeleton of the stem, when removed by maceration, was
found by Kuhn to be a hollow cylinder with large open meshes. These are more
elongated on the ventral side and from these ventral strands alone, according to
Kuhn, the roots are developed. In this respect Kaulfussia offers a certain analogy
to Helminthostachys and perhaps to Ophioglossum pendulum. -

As in the other Marattiacez, the ground tissue of the rhizome is composed of
simple parenchyma. The outer layers have their walls brown in color and show the
reaction of cork. Except for the presence of the central strand, a section of the

186 THE MARATTIALES

rhizome of Kaulfussia presents almost the exact appearance of a similar section of
Ophioglossum.

In a rhizome having a diameter of about a centimeter twelve bundles showed
in a cross-section taken through the internode, one of these being the medullary
strand. The section of a petiole of a leaf taken from the same plant is shown in
fig. 171, C, and the structure of the section closely resembles that of the rhizome.
There were eight bundles arranged in a circle, within which were two medullary
strands. The cortical region was composed of several rows of brownish cells, prob-
ably similar to those in the outer part of the rhizome, and within these, separated

Fic. 171.
Central bundle from a young sporophyte of Kaul- A. Rhizome of a large sporophyte of Kaulfussia. st, stip-
fussta, showing two xylems. X150. ules; com, commissure. 4.

B. Section of rhizome. X2.
C. Section of petiole. X2.

from them by three or four rows of cells, was a conspicuous band of collenchyma,
a tissue characteristic of the leaves of most of the Marattiacez.

According to Kuhn, the bundles of the leaves are continued separately into the
cortex of the stem and do not unite into a single leaf trace. There are occasional
anastomoses of the vascular bundles of the petiole, quite like those in the stem itself,
and this becomes especially marked at the base of the leaf, so that the leaf trace (if
such it can be called) forms a hollow reticulate cone, quite equaling in diameter the
vascular cylinder of the stem itself, and attached to this by the open base, the sepa-
rate strands forming a crescent-shaped group when seen in section. The arrange-
ment of the bundles within the petiole itself and their method of junction with the
vascular system of the rhizome are very much like those in Ophioglossum pendulum.

The vascular bundles, both in the petiole and rhizome, are concentric. The
endodermis is not recognizable and the central xylem is completely inclosed by the
phloem, sieve tubes being developed throughout.

THE OLDER SPOROPHYTE 187

While mucilage ducts are present in both leaf and stem, they are less numerous
and conspicuous than in Danaea. There is a ring of them in the outer cortex and
several larger ones in the central region. Kuhn states that, although these mucilage
ducts sometimes look as if they were of schizogenous origin, in reality they are
always lysigenous, 1. e., they are formed by the fusion of seyecal mucilage-secreting
cells.

In the cotyledon and the earlier leaves a section of the lamina shows, between
the large-celled epidermis of the upper and lower sides, a mesophyll composed of
about three layers of quite indifferent parenchyma, exactly as it is in Ophioglossum.
In the adult leaves the upper part of the mesophyll is compact, but there is no
proper palisade tissue developed. “Toward the lower surface the mesophyll becomes
looser.

Until the plant has reached a considerable size the leaves remain undivided
and, except for the much greater size, closely resemble the early leaves of the young
sporophyte (see plate 11, fg. 1). The simple leaves are succeeded later by trifoliate
ones, and finally five leaflets are developed. The long, fleshy petiole may reach a
diameter of a centimeter or more and a length of some 50 centimeters in large
specimens. ‘The venation strikingly resembles that of a dicotyledonous leaf, the
pinnately arranged, secondary veins being connected by a plexus of small veins,
inclosing nearly square areoles within which a few free terminations are occasionally
found. The large pores upon the lower side of the leaf, formed by the greatly
enlarged stomata already referred to in the younger leaves, are plainly visible to the
naked eye, and sections of these look curiously like the pores upon the thallus of
certain Marchantiacee (fig. 128).

The stipules of the older leaves are very conspicuous and show much the same
structure as that noted for the earlier leaves. The young leaf is included within the
stipular sheath of the next older one, and near the apex the unbroken stipular sheath
of the youngest expanded leaf shows very plainly that the large stipules are joined
in front by a broad commissure, which extends entirely around the apex of the shoot,
exactly as it does in Helminthostachys, from which the sheath differs mainly in the
fact that it is divided above into the ane stipules as it is in Botrychium virginianum,
and there seems no reason to doubt that we have to do with entirely homologous
structures (fig. 171, 4). The stipules of the young leaves are covered with hairs
and scales similar to those noted in the young sporophyte.

The roots arise from the ventral surface and flanks of the rhizome, and out-
number the leaves, to which they apparently bear no definite relation.

The apical growth was not studied in the root of the older sporophyte, but it
is probable that in the large roots of the older plant the single apical cell found in
the early roots is replaced by a group of initials such as are found in the other
Marattiacez, although it is barely possible that the single apical cell may be retained
here as it is in the Ophioglossacew. Unfortunately, material was not available for
a study of this point. The roots in most cases are quite unbranched, as they are in
Euophioglossum. The only cases where branches were seen, were young sporophy tes
in which the end of the root had been destroyed and two branches had arisen on
each side of the destroyed apex. This looks somewhat like a dichotomy and it is
barely possible that, as in Ophioglossum, there may be a real dichotomy of the root,
but all of the cases that were found had much more the appearance of the formation
of two lateral roots. The young roots of the sporophyte are provided with multicel-
lular root hairs, like those of Danaea, but these disappear as the root becomes older.

The central vascular cylinder of the root is surrounded by a circle of very large
mucilage ducts. The endodermis is clearly evident and the roots which I cd

188 THE MARATTIALES

from a medium-sized plant were tetrarch. Kuhn states that pentarch and hex-
arch roots also are formed. ‘The reduced number of xylems in the root of Kaul-
fussta, as compared with the other Marattiacea, is another indication of its probable
nearer relationship to the Ophioglossacez, the structure of the root being very similar
indeed to that of Helminthostachys or Ophioglossum pendulum.

THE SPOROPHYTE OF MARATTIA.

The published observations upon the young sporophyte of Marattia are far
from complete. Kiihn (Kihn 1) has described the stem structure in young plants
of M. fraxinea, but it is evident that these plants were already too far advanced
to show the early arrangement of the bundles, as the stems he described had
reached a length of nearly 2 centimeters. Farmer and Hill (Farmer 3) have also
given some details as to the early stem structure in the same species. These young
plants, especially those described by Kuhn, have the stem relatively longer than is
the case either in M. douglasi1, which I have studied somewhat in detail, or M.
alata, or M. sambucina, which | have also examined. In all of these species the stem
of the very young sporophyte is still quite short and very soon assumes the compact
globular form with the crowded leaves that it has in the adult sporophyte. It may
be said, however, that in M. alata the buds which develop upon the old leaf bases
have the young stem somewhat more elongated, but not nearly so much as Kiihn’s
figures would indicate to be the case in M. fraxinea.*

In the youngest specimens examined by Kuhn the cross-section of the stem
showed a ring of bundles corresponding to the leaf traces and a central medullary
strand, the whole arrangement being very similar to that which is found in the
adult rhizome of Kaulfussia. his stage is also very similar to the condition found
in the young sporophyte of Danaea.

Farmer and Hill describe the vascular skeleton of the very young plant of M.
fraxinea as a “siphonostele”’ with much larger foliar gaps than those found in
Angiopteris, and thus more nearly resembling Kaulfussta or Danaea. ‘The leaf
traces are at first single, but the later leaves have double leaf traces, such as we have
described in Danea and Kaulfussia.

The writer has already published some details in regard to the young sporo-
phyte of Marattia douglast: (Campbell 3, 4), and some additional facts are here
added to those that have already been published; but as the series of specimens
available for study was not at all complete, further investigation is desirable to
complete the history of the development of the vascular system in Marattia. The
only material available for a study of the young sporophyte in M. douglasi: was a
series of slides made a good many years ago from material collected on the island
of Kauai in the Hawaiian Islands. This material was supplemented by a small
number of very young plants of M. sambucina, collected in Java. Material of older
sporophytes of M. alata was collected in Jamaica in the summer of 1908. Un-
fortunately, all the preparations of M. douglasi1, except the very youngest stages,
were longitudinal sections, so that it was difficult to follow out satisfactorily the
course of the vascular bundles in the later stages.

Longitudinal sections of a young sporophyte before the cotyledon was com-
pletely expanded are shown in fig. 133. The section was cut nearly in the plane of
the cotyledon and the bent-over apex of the latter was cut so as to show plainly the
two lobes arising from the first dichotomy of its apex. The second leaf is already
formed and differs in no essential particular from the corresponding leaf in | Kaul-

* Since the above was written a paper has appeared (Charles 1) describing the vascular system of the young sporo-
phyte of M. alata. The stele of the very young plant is described as a protostele which passes abruptly into a solenostele.

THE OLDER SPOROPHYTE 189

fussta or Danea. It was not quite certain whether a single apical cell was present
at this stage, but a triangular cell which could be seen at the apex was probably
the apical cell of the young leaf. The root apex of this specimen had been injured
so that the form of the apical cell could not be clearly made out, but it was probably
the same as we have already described for the young sporophyte. The apical cell of
the stem meristem was broader in outline than that of Danea and truncate below.

The vascular system at this stage, as we have already indicated earlier, consists
of the common bundle of the root and the cotyledon, which is joined at a point quite
close to the stem apex by the second leaf trace. Tes ae tracheary tissue ts visible
at this point in the form of short, reticulately marked tracheids such as we have
already seen in the young sporophyte of Danaea. At this stage no mucilage ducts
or tannin cells had developed. About the base of the young leaves are short hairs

Fic. 172. FiG. 173:
A, B. Two longitudinal sections of a young Section of a young sporophyte of Marattia
sporophyte of Marattia douglasii. 1°, douglasti. st, stem apex; /, young leaves;
second leaf; r~, second root. X140. r, roots. X25.

C. Part of primary root, showing cells in-
fected by endophytic fungus.

and scales like those we have seen in the other genera. They are more like those of
Kaulfussia than like the peltate scales found in Danea.

Sections of a somewhat older sporophyte are shown in figure 172, this section
being made at right angles to the one just described. The cotyledon in this specimen
was fully expanded and the primary root had penetrated into the earth. The
arrangement of the bundles was the same as in the younger sporophyte described,
except that the third leaf was now visible and the second root was already well
advanced. The section passed exactly through this root, the stele of which is seen
to join that of the second leaf and is practically continuous with it. The young
trace from the third leaf joins the second leaf trace near its junction with the second
root. The apical cell of the latter was readily seen and appears in longitudinal
section of nearly triangular form, but with the base somewhat truncate (fig. 177, C).

The tracheary tissue in the middle of the sporophyte is pretty well "advanced
and the formation of the tracheary tissue has extended for some distance into the
primary root and the cotyledon. In the former a single elongated tannin sac could

190 THE MARATTIALES

be seen, like those which are much more developed in the primary root of Angrop-
terrs, and it was also seen that certain of the cells in the cortex of the primary roots
were invaded by the endophytic fungus. In the cotyledon there was a single large
mucilage duct.

A series of transverse sections was made of a young sporophyte of M. sam-
bucina and these agreed in all essential particulars with similar sections of Danawa
or Kaulfussia.

In a young sporophyte of M. douglasi1, in which two roots were developed in
addition tothe primary one, there could be seen at the apex two young leaves, prob-
ably the fourth and fifth, but as only the median sections of this series had been
kept the exact number of leaves could not be determined.

The central part of the stem in this plant (fig. 173) was occupied by a single
thick bundle, but whether this was solid or open on one side, as Farmer states is

Fic. 174.

A, B. Two longitudinal sections of an older sporophyte of Marattia douglasti. st, stem apex; m, mucilage ducts. X25.
C. Stem apex. 180.

the case in M. fraxinea, could not be satisfactorily determined. At this stage the
section of the young plant almost exactly resembles a similar one in Danaa, and
presumably the single central strand is composed of the confluent leaf traces from
the three first leaves, as it is in Danea.

The xylem of the bundle is still composed exclusively of short, reticulate tra-
cheids. Large mucilage ducts and numerous tannin sacs are developed in the
petioles of the older leaves and the elongated tannin sacs, like those in the roots of
Danea and Angiopterts, are sparingly developed in the young roots; but both tannin
sacs and mucilage ducts were absent from the stem tissues at this period.

In a still older plant (fig. 174) the single central bundle of the basal region is
replaced by the separated steles of the single leaf traces, which are beginning to form
the open dictyostele characteristic of the adult sporophyte. The exact nature of its
origin could not be followed in the material at my disposal, but it is presumably

THE OLDER SPOROPHYTE 191

much the same as that described for Danea, since the appearance of the longitudinal
sections in Marattia is exactly like that of corresponding stages in Danaea. The
apex of the stem, however, is much broader than in Danea. There is in the middle
of the apical region a cell which from its size and position may be pretty certainly
denominated the apical cell (fg. 174, C). There is present a strand of procam-
bium which ends abruptly a short distance below the stem apex. This strand
probably represents the primary commissural strand, which, as in Danea, is in
all probability a truly cauline bundle and has no direct connection with the leaf
traces. In the central region of the stem there are now several large mucilage
ducts, but tannin cells are still absent. In the roots, however, the tannin cells are
abundantly developed.

Farmer and Hill’s brief account of the development of Marattia fraxinea agrees
with my own observations so far as they have gone, except for the interpretation
of the vascular bundles. The “protostele” found in the lower part of the stem is
undoubtedly the common bundle of the primary root and the cotyledon, and the
open “‘siphonostele” is really made up of separate leaf traces, which anastomose
at certain points to form the large meshes of the very open dictyostele. Farmer and
Hill call attention to the fact that the “foliar gaps” are much wider than in Angr-
opterts, and in consequence the separate strands, seen in section, form a circle of
apparently quite separate bundles, evidently closely approximating the condition
found in Dan@a and Kaulfussta. Farmer and Hill ‘do not make it quite clear that
the commissures which they found developed later, connecting the strands of the
dictyostele, were really parts of the central cauline strand, but they presumably
assume that such was the case, as this is explicitly stated in the case of Angropterts,
which they also studied. The structure of the bundle in the latest stage described
by Farmer and Hill agrees pretty closely with the condition described by Kuhn in
the youngest specimens which he studied, where the stem was about a centimeter
in diameter.

The early leaf traces, as in the other Marattiacez, are single, but later on double
traces are formed. According to Farmer and Hill, the two bundles of the leaf trace
unite before joining the vascular cylinder of the stem. No material was available
for a further study of the development of the bundle in M. douglasi1, but it probably
agrees with that of M. fraxinea.

Several young plants of M. alata were examined for comparison with the young
germ plants of M. douglasi:. The specimens in question (fig. 175) had arisen as
adventitious buds upon the old leaf bases which had become separated from the
stem. This manner of formation of the young plants 1 is very common in this species
(see plate 12, A). In one of these young plants, in which the stem was about 4
centimeters long and 1.5 centimeters in diameter, exclusive of the leaf bases, the
oldest expanded leaf had a petiole of about 8 millimeters in diameter. In these
young plants there is usually only one leaf expanded, so that they have a very different
appearance from the fully developed sporophyte with its crowded circle of leaves,
and these monophyllous plants remind one very much of sterile specimens of some
of the larger species of Botrychium (plate 12, B). A section of the petiole of this
specimen showed ten vascular bundles arranged in a circle, within which, on the
ventral side, were two other bundles. ‘The section resembled almost exactly that
of the petiole of a fully developed leaf of Helminthostachys. At the base of the leaf
are the two very conspicuous stipules, one of which overlaps the other. These
stipules are connected by a commissure which joins the two stipules near the base
and is entirely concealed within the cavity formed by the overlapping. stipules,
but can be seen on raising these, as a hood-like membrane, overarching the next

192 THE MARATTIALES

younger leaf. Fig. 175, £, shows a young leaf from another plant, in which one
side has been cut away so as to show the relation of the stipules to the leaf base.
This leaf was still coiled up and its apex was quite concealed within the large
overlapping stipules. Both as to its position and its relation to the stipules, the
commissure exactly resembles the lip-like basal extension of the stipular sheath in
Botrychium and Helminthostach ys, and there is no reason to suppose that it is not
ex xactly homologous with this.

Partially inclosed by the stipular sheath of the expanded leaf is the next younger
leaf, which is cut in a plane nearly at right angles with that of the oldest leaf, so that
the overlapping of the stipules, which entirely conceal the rest of the leaf, is very
plainly seen (fig. 175, B, ?). Within the stipular sheath of this leaf is a still younger
one, which is entirely concealed from view from the outside, but shows plainly i in
longitudinal sections, taken next to the center of the bud. The stem apex ts entirely
concealed within the sheath of the younger leaf. The resemblance of this section of

Fic. 175.—Marattia alata Smith.

A, B. Young plant developed as a bud upon an old leaf base. The outer tissue has been cut away, and the two sides
of the thick central section are shown. Xt.
C. Section of petiole of leaf.
D. Three sections of a rhizome of a small plant. 1.33
E. Young leaf. The lamina is coiled up within the large stipules, st. In (1) one of the stipules has been cut away
to show the commissure, com. X1.33

the young plant to a similar section of the bud in one of the larger species of Botry-
chium or of Helminthostachys is sufficiently striking.

The bundles forming the ring in the petiole anastomose freely in the leaf base,
as they do in Kaulfussia or Ophioglossum pendulum, so that the number of strands
in the leaf trace is smaller than the number of bundles within the petiole.

The vascular bundles in the stem form a single very open mesh-work, with
which the leaf traces join and which is, with little question, composed entirely of
these leaf traces, as it is in the earlier stage. Indeed, except for the larger size of
these plants, there is no essential difference between them and the young germ
plants, described in M. douglasit. Several roots are usually developed before the
first leaf of these young bud-plants unfolds. Probably one root develops for each
leaf, but it is not certain that this is always the case. Owing to the thickness of the
cortical region which has to be traversed by the root before it emerges, the roots
have already reached a large size before they appear upon the outside. This deep-

THE OLDER SPOROPHYTE 193

seated origin of the roots of the Marattiacez has often been figured and described.
The roots from the base of this plant showed the hexarch structure, the six xylem
masses being united in the middle of the stele. About half-way between the stele
and the epidermis of the root is a circle of large mucilage ducts, but these were quite
absent from the outer cortex. No mycorrhiza could be found, except that in the
outermost layers of cells, which constitute a rudimentary periderm, occasional fungus
filaments can be detected, but these are very different in appearance from the
typical mycorrhiza found in the primary root of the germ plant. No root hairs could
be found, but occasionally short stumps were seen which looked as if a root hair
had Lae broken off.

Fig. 175, D, shows three consecutive free-hand sections of a stem from a
plant an about the same size as the one we have just described, but evidently much
older, as there were the remains of many leaves and the whole caudex, except for
its smaller size, was very much like that of the adult plant. The broad vascular
strands made up of the confluent leaf traces formed an irregular circle which in
fig. 175, D, 2, 3, shows the free central strand which lower down forms the com-
missure across the central parenchyma. The arrangement of the bundles, therefore,
in the young plant of Marattiacex is the same as in die adult rhizome of Kaulfussta.
In these sections two roots are shown, one of which is cut through the point of
junction with a strand of the dictyostele (fg. 175, D, 1). As in the younger germ
plants, tannin cells are quite absent from Te: stem, although in the roots “they are
conspicuous. A few large mucilage ducts, however, occur in the ground tissue of
the stem.

Farmer and Hill give one figure of a cross-section of the stele from the young
stem of Marattia mich shows that it has essentially the same structure as that of
Danea. There is a fairly well-marked endodermis, within which lies a broad zone
of phloem, entirely surrounding the central mass of xylem.

According to Kuhn, there is in the older plant a second circle of bundles within
the first, but no satisfactory account is given as to the relation of the bundles making
up this second circle with those of the outer dictyostele. However, it is probably
composed also of elements derived from the leaf traces, but it is possible that some
of the strands may be of cauline origin.

THE ADULT SPOROPHYTE OF MARATTIA.

The Bente Marattia includes about 25 extremely variable species, some of
which, e. g., M. fraxinea, closely resemble Angiopteris in their general habit (see
Bitter 1, te 441; Christensen 1). They occur in the moist, tropical regions of
both the Old and New World, and one species, /. saltcifolia, extends as far south
as the Cape Region of South Africa. M. douglast: is a conspicuous fern of the
Hawaiian isan This species I have studied somewhat in detail, as well as the
West Indian M. alata, which is abundant in the mountain forests of Jamaica. These
two species closely resemble each other in general habit and have the leaves very
much more divided than ts the case in M. fraxinea and its allies (see plate 12).

The stem in the adult plant is an almost globular, upright caudex, a foot or
more in diameter in large plants. The closely set, spirally arranged leaves have
very stout petioles, 5 or 6 centimeters in diameter at their base, which is enlarged
and provided with two very large wing-like fleshy stipules, which, with the base of
the leaf, remain attached and completely cover the caudex after the petioles have
fallen away. There is at the base of the leaf, as in the other Marattiacez, a pulvinus-
like enlargement, where the leaf breaks off, leaving a clean scar marked by the broken
ends of the vascular bundles. The leaves may each a length of 2 to 3 meters cr

13

194 THE MARATTIALES

even more. ‘The thick, fleshy texture of the leaflets, much like that of Botrychium
ternatum or B. silaifolium, at once distinguishes Marattia from any of the large
leptosporangiate ferns with which it may be associated. The resemblance to the
leaves of Botrychium is especially marked in the young plants growing from the
stipular buds. These leaves show a marked triangular outline, curiously similar to
that of the larger species of Botrychrum (see plate 12, B). The venation of the leaf-
pay is also very like, resembling that of Botrychium more than it does that of Danaa

t Angiopteris. In the species with large linear leaflets, e. g., M. fraxinea, the form
of the leaf is quite similar to that of Angtopterts or Danaa, but the veins are not so
closely approximated.

The structure of the leaf was particularly studied in M. alata, which closely
resembles the Hawaiian M. douglasi:. In well-grown specimens the leaves measure
2 or 3 meters in length, with a petiole which is 5 or 6 centimeters in diameter above
the insertion of the stipules and is somewhat larger lower down. Where it joins
the stem there is a marked constriction and the leaves often become broken off at
this point, the fleshy leaf base remaining alive and often giving rise to adventitious
buds (plate 12, A, 3). A section of the leaf base above the stipules shows the vascular

Fic. 176.

A. Section of ultimate rachis of a leaflet of Marattia alata. The shaded area is collenchyma; m, mucilage ducts.
B. Collenchyma cells, more highly magnified.
C. Part of vascular bundle. The shaded cells are tannin sacs.

bundles to be arranged in two large concentric circles, within which is a smaller
third ring corresponding to the two inner bundles found in the section of the younger
leaf. Below this point there are numerous anastomoses of the bundles before they
enter the cortex of the stem, and the leaf trace consists of a much smaller number
of bundles, eight in the specimen examined, which are arranged in a single circle,
open on the adaxial side. The distribution of the bundles to the stipules was not
studied, but it no doubt corresponds to that in other species, where the veins form
an extensively branched system, connected with the bundles of the petiole.

The large leaves of M. alata, when fully developed, are five-pinnate, the ultimate
leaflets being about 2 centimeters long. From the midrib extend lateral veins which
usually fork once but may remain undivided (plate 12,A,1). The bundles of the

rachis in the later divisions of the leaf diminish in number and show the horseshoe-
like arrangement seen in the leaf trace after it leaves the petiole. In the final divisions
the crescent of bundles seen in the larger rachis is always completely united and
in section appears as a single horseshoe-shaped bundle (fig. 176, 4). In the main
stipe and secondary and tertiary rachis there is a conspicuous hypodermal sheath
of sclerenchyma. This sclerenchyma passes into collenchyma near the base of the

THE OLDER SPOROPHYTE 195

stipe and finally disappears entirely before the stem is reached. ‘The sclerenchyma
is also replaced by collenchyma in the rachis of the terminal divisions of the leaf.
Tannin sacs are quite absent except from the immediate vicinity of the bundles,
where they occur upon the inner concave side, either in direct contact with the bundle
or actually within it. The leaf lamina ts only about half as thick as that of the leath-
ery leaf of Danea elliptica, but shows much the same structure. The palisade cells
are not quite so well developed and there is a complete absence of sclerenchyma, but
otherwise the structure is very similar. The cells of the epidermis are undulate in
outline and the stomata, like those in Danea, are surrounded by a series of accessory
cells.

The large roots may attain a diameter of 6 to 7 millimeters. In the absence
of the hypodermal sheath of sclerenchyma they more nearly resemble Kaulfussia
than Danea, but they are more like Danea in the greater number of xylem rays,
which number twelve in the largest roots examined. In these later roots the central
part of the stele is occupied by the pith, the xylem rays not being united as they

- Apex of a small root of Marattia douglast1, showing two initial cells.
. Transverse section of apex of a similar root.

. Longitudinal section of the apex of the second root.

- Apex of a large root of M. alata. x x, initial cells. X200.

SDOme

are in the roots from the younger plant, but in some cases a few scattered tracheids
appear in the central region. There is usually a ring of conspicuous mucilage
ducts in the cortex, but these were sometimes not very well developed. Numerous
tannin sacs are scattered through the cortex and also occur within the stele.

THE SPOROPHYTE OF ANGIOPTERIS.

Angtopterts is the largest and most specialized of the Marattiaceew. As we have
indicated before, there is much difference of opinion as to the number of species
which should be recognized and many botanists consider that all of the forms belong
to a single extremely variable species. Bitter, however, in his account of the Marat-
tiacee in the “Naturliche Pflanzenfamilien,” thinks that from 20 to 30 species
should be recognized, following in this respect the classification given by Presl and
De Vries; while Christensen (Christensen 1) recognizes 62. I have examined ma-
terial from Australia furnished by Mr. J. H. Maiden, director of the Botanical
Gardens in Sydney, as well as material collected by myself in Ceylon and Java.
Some of the specimens growing in the Botanical Garden at Buitenzorg are the
largest that I have seen. Leaves 6 meters and upwards in length were measured and
the upright caudex was almost as big as a barrel. ‘The specimens seen in Ceylon
were somewhat smaller.

196 THE MARATTIALES

Forms of Angropterts occur from Polynesia to Madagascar and northward as
far as the Himalayas. ‘The genus also occurs in northern Australia.

The anatomy of the adult plant has been investigated more thoroughly than
that of any other member of the Marattiacea. The most recent account of the
anatomy is that given by Miss Shove (Shove 1), while Farmer and Hill have care-
fully investigated the vascular system of the young sporophyte. A number of prep-
arations were made by the writer for the purposes of comparison with the other
genera, but no attempt was made to follow out in detail the extremely complicated
vascular skeleton of the adult sporophyte. Farmer and Hill (Farmer 3) have given
a detailed account of the development of the vascular system in the young sporo-
phyte of Angiopterts, so that it was not thought necessary to make a large number
of preparations of this species, the material of which was collected at the same place
where Farmer obtained his plants. However, as these authors did not trace the
development of the young bundles from the apical meristem, it seemed worth while
to examine this point for the purpose of supplementing their account based upon
the study of the fully developed vascular skeleton.

5

1 te A B D

Fic. 178.—Four longitudinal sections of a young sporophyte of Angsopteris.

The vascular system begins, as was recognized by Farmer in an earlier paper
(Farmer 1), as a single strand connecting the root and cotyledon, exactly as is the case
in the other Marattiacez. In the further study of the dev elopment of the vascular skel-
eton Farmer and Hill employed the method of constructing a model of the vascular
system, built up of superimposed sheets of wax, corresponding with the outline of
the vascular bundles seen in the serial sections. The figures which they give,
drawn from such models, show very clearly the relation of the vascular strands
which make up the complicated skeleton in Angropterts. The assumption is made
that the single stele found in the young plant is really a cauline structure, the leaf
traces being subsidiary. The early history of the vascular system of the young
sporophyte is given by them as follows:

“The vascular skeleton in the young plant of Angiopterts consists of an axile
rod of tissue, from which strands are given off to the roots and leaves respectively.
The first lateral root is given off at a point not quite opposite the formation of the
first leaf trace. It is separated from it by about 130°. The regular relation be-
tween the leaf and the corresponding root is, however, soon lost. The gaps produced
by the early leaf traces are very small and are immediately made good above. The

THE OLDER SPOROPHYTE 197

first deeply depressed aperture or gap occurs at about the sixth or seventh leaf.
The leaf traces still continue to issue from the stele as single strands till a varying
number have been formed, but they begin to bifurcate while still within the cortex
of the stem.

“As the stem increases the leaf traces become more numerous and crowded and
they take away a larger portion of the vascular tissue from the axile strand. The
result is that the leaf gaps become less rapidly repaired. The stele is already hollow
in this region, that is, it consists of a cylindrical vascular mass with perforations
corresponding to foliar gaps and inclosing a core of parenchyma. Sooner or later,
the gap above one leaf fails to be repaired until after the exit of the trace of the next
leaf and then the original vascular cylinder becomes broken up and assumes a
condition, in transverse section, conforming with that of polystely or dialystely.”

There is thus a gradual transition from the solid stele found in the earliest stages
to a hollow cylinder or siphonostele with a core of pith, and by the formation of larger
and larger leaf gaps there is a transition to an open dictyostele like that found in the
other genera. Finally there appears the commissural strand which forms a thick

As

Fic. 179.

A-D. Four transverse sections of a very young sporophyte of Angiopteris. A, traverses stem apex. B, C, show
the fusion of the first three leaf traces.
E. Central region of C. 200.
F. Central region of D. 200.

strond traversing the pith and undoubtedly of cauline origin. This central strand
becomes more and more important as the plant develops and from its central
position might be mistaken for the original axial strand of the young sporophyte.
The vascular system at this stage is described as follows:

“The leaf traces become more complex and anastomoses take place at irregular
intervals with the strands which can still be recognized as the relics of the original
siphonostele, as well as with one another. Irregularities also commence to become
apparent as to the relative heights at which the two members of the leaf traces be-
come freed from the plexus of tissue, and a stage ts thus reached at which the vascular
skeleton appears to consist of a stout axile strand, surrounded by upwardly diverging
zones of steles, which ultimately pass out above to the leaves.”’

It is evident that at this stage there is a condition which is very much like that
figured by Kuhn for Kaulfussra, and it is pretty clear that the whole of the dictyostele,
exclusive of the axial or commissural strand, is made up of the “upwardly diverging
zones of steles which pass out above into the leaves,” i. e., in other words, the
dictyostele is composed of a union of multiple leaf traces.

198 THE MARATTIALES

‘Transverse sections of a very young sporophyte of Angiopteris show the same
relation of the parts as in the other genera. The junction of the traces of the first,
second, and third leaves takes place at a very short distance below the stem apex,
which, as Farmer pointed out, shows an unmistakable apical cell of somewhat irregu-
lar form. Compared with the other genera, the primary leaf trace in Angiopteris has
the xylem better developed, and composed of about half a dozen tracheids, where
the trace enters the stem. This primary leaf trace is concentric, as it is in the later
leaves, and not collateral, as it is in Dana (fig. 179).

Near the point of the junction of the three primary traces, there may be seen
in the young traces from the second and third leaves the first tracheary tissue,
consisting of one or two tracheids. As the sections are examined lower down the
tracheary tissue of the second and third leaf traces increases in amount until it
forms a solid band, separated from the corresponding xylem of the primary leaf
trace by a band of parenchyma. ‘The three leaf traces are now completely fused, but
the sections of the two xylems are perfectly evident, and this band of tissue between

Fic. 180.

A-D. Four sections of an older sporophyte than that shown in fig. 179. X40.
E. Stem apex. 130.
F. Central bundle from transitional region.
G. Bundle of primary root.

the two xylems (which really belongs to the ground tissue of the stem and not to the
stele itself) corresponds to the “pith” figured by Farmer and Hill for the transi-
tional region between the root and stem (fig. 180, C). Sometimes, in still lower
sections, the two xylems are connected, but I have found no cases where the pith
was entirely surrounded by the xylem, and the two xylems of this axial strand merge
gradually into the two xylems of the diarch primary root (fig. 179, G). The endo-
dermis is clearly evident in the intermediate region and is recognizable also at higher
levels, but is less easy to distinguish.

In a series of sections, from a plant in which the fifth leaf was just recognizable,
a section at the level of the stem apex shows the apical meristem to be composed
of several large cells, one of which is probably the single apical cell, but this is not
easy to determine. The base of the fifth leaf is close to the apical group and the
section of its stele is indicated by a group of small cells close to the stem apex. The
stele of the third leaf is clearly seen, separated from the fourth leaf by about one-
third the circumference of the stem. Below the stem apex these two leaf traces

THE OLDER SPOROPHYTE 199

approach, but are still separated by a considerable mass of tissue, lying directly
under the stem apex. The two bundles finally join and between them there seems
to be a sort of connective tissue which may perhaps belong to the stem itself, so
that this central stele of the stem may possibly have a certain amount of cauline
tissue in addition to that derived from the leaf traces; but it is quite as likely that
this connective tissue between the bundles is nothing more than a lateral extension of
the leaf trace itself, very much as is the case in Hel Iminthostachys and Botrychium.

Fic. 181 SRS) of transverse sections from a sporophyte of Angiopteris, showing 5 leaves.
r>, r°, second and third roots. X25. _B, traverses the stem apex.

When the fusion is complete, the section of the stele appears circular in outline
and the whole of the tissue is apparently quite uniform, with the exception of a single
tracheid marking the position of the xylem of the older leaf trace. There follows
almost immediately the older leaf trace which joins the solid stele, formed by the
fusion of the traces from the third and fourth leaf, without causing any break. At
this level the first tracheary tissue can be seen in the fourth leaf trace also. The
structure of the stem below the junction of the second and third leaf traces is the
same as that already described for the younger sporophyte. A very young root was

200 THE MARATTIALES

formed just opposite where the second leaf trace joined the stele. The apical cell,
which had apparently developed from an endodermal cell, had only undergone the

first division. This root was probably not the first lateral root, or if it was, it had
formed very much later than is usual. The base of the plant had been somewhat
injured and there was what looked like the remains of another root, which was
probably the first lateral root.

The oldest specimen of which sections were made had four fully developed
leaves and the rudiments of the fifth and sixth. An examination of the lower series
of sections showed the remains of one or two other leaves and it was probable that
eight leaves all together had been formed. At the level of the stem apex (fig. 181, B)
six separate leaf traces could be seen and the relation of the younger ones to the apex
was exactly the same as in the younger sporophyte. Below the apex, the central
stele of the stem shows a broken ring of procambium inclosing larger parenchyma,
representing the pith. The procambium ring is made up evidently of two portions,
one of which is certainly referable to the sixth leaf trace, while the opposite one
perhaps represents the beginning of the next leaf trace, although the leaf to which
it belongs is not yet evident above (hg. 181, D). The junction of the leaf traces so
close to the stem apex makes this point very difficult to decide.

The fusion of the fifth and fourth traces follows quickly and the resulting stele
shows plainly the three separate xylems of its component bundles. The older
portion of the stele shows that it is still solid, with no evident leaf gaps (fig. 181,
E-G), but with several groups of tracheids probably corresponding to as many leaf
traces, though less distinct than in the younger plant. This ts complicated by the
fusion of the root traces, which disturbs the arrangement of the xylems from the
leaf traces, but the xylem is less compact than is figured by Farmer and Hill and
the “ pith”? much less definite; indeed, one can hardly speak ofa pith in this connec-
tion. No trace could be seen of the central commissural strand which later makes
its appearance and which presumably arises in the same way that it does in Danea.

In the early stages Angiopterts appears to agree closely with the other Marat-
tiacez in the development of its vascular system, but the single central stele without
leaf gaps is retained much longer than in the other genera and it also becomes much
larger and has a better-developed xylem, and the open dictyostele, formed from the
anastomosing of the early single leaf traces, characteristic of Danea and Marattia,
is not present. It is not quite clear whether the “‘siphonostele”’ with its small leaf
gaps, which is the next stage in the development, i is made up entirely of leaf traces,
and it is possible that the stelar tissue, connecting the adjacent leaf traces, may be
composed in part of cauline tissue. On the other hand, it is quite as likely that the
connection of the leaf traces is brought about merely by a broadening at the point
of contact, such as occurs in Helminthostachys. Indeed, at this stage, the stele of
Angiopterts | is more like that of Helminthostachys than like that of the other Mafat-
tlacez.

THE ADULT SPOROPHYTE OF ANGIOPTERIS.

In habit Angiopteris closely resembles the larger species of Marattia. The
enormous leaves are arranged spirally about the thick upright caudex, which is
covered completely by the persistent bases of the old leaves. The leaves are usually
twice-pinnate; the linear leaflets have more or less conspicuously serrate margins
with a venation very much like that of Danea, the veins being more closely set than
in Marattia. In addition to the ordinary subterranean roots, large aerial roots are
not infrequent, but it is doubtful if there is any essential difference between the two
kinds of roots.

THE OLDER SPOROPHYTE 201

The anatomy of the stem closely resembles that of Marattia, but the bundles
seen in section are much more numerous and instead of being arranged in two
circles, exclusive of the central commissural strand, are usually arranged in'four or
five. The first complete study of the arrangement of the bundles in the stem was
made by Mettenius (Mettenius 2). A summary of his results is given in the paper
by Miss Shove. Briefly stated, Mettenius describes the distribution of the bundles
as follows (Shove I, p. 498):

“The vascular bundles form funnel-shaped zones, with their lower ends in the
axis of the stem and their upper portions continued out into the leaves as leaf traces.
It is the transverse sections of these concentrically arranged funnels which appear
as the rings of separate bundles in the section of the stem. Segments from the outer
zone pass into the leaves as the leaf traces and the gaps thus left are filled up by
corresponding segments from the next inner zone.”

The detailed account made by Miss Shove was based upon a moderate-sized
specimen from Ceylon. This stem is described as being somewhat dorsiventral in
structure, which is certainly not usual in Angiopteris sid may perhaps be explained
by the conditions under which the plant was growing. | found Angiopteris growing
frequently upon steep banks and it is quite possible that plants growing in such a
position might be obliged to bend upward, in which case a somewhat dorsiventral
structure would be developed. Plants growing upon level ground, so far as my
observations go, are always strictly radial in structure.

Miss Shove found essentially the same structure as that described by Mettenius,
except that she states that the leaf traces are developed exclusively from the strands
of the outer zone, while Mettenius states that strands are also contributed to the
leaf trace from the second zone. ‘The following is taken from her paper (Shove 1):

“The general scheme of the arrangement of the vascular tissue in 4n glopterts
is almost clearly conceived by considering i it in connection with the insertion of the
leaves. The leaf bases, which are set in a rough spiral on the stem, show in their
lower parts a meshed segment of vascular tissue having the form of part of the sur-
face of a cylinder. This segment passes from the leaf en into the outermost zone
of the stem, uniting right ad left with the strands of this zone. Then, continuing
in an obliquely descending direction, it passes on into the second zone and so on
until it reaches the longitudinal axis of the stem, where it unites with other leaf-
trace bundles and loses all individuality.”

Miss Shove found that the steles in the stem were both mesarch and endarch
in structure. The protoxylem is found in groups of two or more spiral tracheids,
some of them at the periphery and some in the center of the stele. “The number of
protoxylems varies with the size of the stele, the larger ones usually containing five
or six such groups. The earliest protoxylem appears at the periphery of the stele.
Protophloem is developed upon the outer side of the stele in the form of discontinu-
ous, small, thick-walled elements, which Miss Shove regards as sieve tubes. This
protophloem does not occur upon the inner side of the xylem. A remarkable pecu-
liarity of the bundle is the fact that the secondary sieve tubes are formed outside the
protophloem instead of within it. The phloem is of greater breadth on the outer
side of the stele than on the inner. No endodermis could be detected about the
steles in the stem. The usual absence of sclerenchyma was noted for the stem. Miss
Shove was unable to determine the nature of the apical meristem and the question
still remains open, whether the stem grows from a single apical cell or from a group,
such as is found in the larger roots.

It appears from the account of both the older and more recent investigators
that the complicated system of concentric meshed zones in the adult stem of Angiop-

202 THE MARATTIALES

ters is really built up of leaf traces, the so-called “compensating segment” being
nothing more than the lower part of a leaf trace which higher up emerges as a meshed
segment from the outer zone and passes into the base of the leaf.

The structure of the petiole (fig. 182, 4) is like that of Marattia, except that
the vascular bundles are more numerous and are arranged in several circles, inclos-
ing one or two small bundles in the center. A cross-section of a leaflet (fig. 182, B)
shows the vascular bundle which traverses the midrib to be horseshoe-shape in
section, having a central mass of tracheids, with reticulate or scalariform markings,
and surrounded by the phloem, largely made up of large sieve tubes, but having
also protophloem cells and bast. The ground tissue is composed largely of paren-
chyma, but on both sides below the epidermis is a conspicuous band of collenchyma.
In the larger divisions of the leaf the collenchyma, as in Marattia, is replaced by
sclerenchyma. ‘The structure of the lamina is very much like that of Danaea, but
the palisade parenchyma is even better developed.

A comparison was made of the leaves of two forms (species ?) of Angiopterts,
one from Australia, the other from Ceylon. These showed several notable differ-
ences. The leaflets of the Ceylonese specimens were thinner and sharply serrate,

Fic. 182.—Angiopteris.

A. Section of petiole from an adult sporophyte, somewhat reduced.
B. Section of a leaflet. col, collenchyma; fp, palisade tissue. X14.
C. Part of sporophyll, showing the sori. 4.

while in the Australian specimens the serrations were almost wanting, except at the
tapering apex of the leaflet. There were also marked anatomical differences. In
the Australian form the palisade cells are very much elongated and are separated
from the epidermis by a layer of colorless hypodermal cells, and the spongy meso-
phyll of the lower part of the leaf 1s decidedly more compact than in the form from
Ceylon. In the latter, the palisade cells are noticeably shorter and abut directly
upon the epidermis. Undoubtedly the differences in the anatomy of the two forms
are associated with the difference between the moist, tropical climate of Ceylon and
the drier and cooler climate of Australia, and perhaps do not necessarily imply that
the two species are distinct, although it is highly probable that such is the case.

The roots originate, for the most part, in the inner zones, but a few may arise
in connection with the bundles of the outer zones and must necessarily traverse a
very large amount of tissue before they finally emerge.

Russow (Russow 1) described two sorts of roots—earth roots which were
branched and had but five xylem rays completely lignified to the center of the bun-
dles, and aerial roots which were much larger and unbranched and had twelve to

THE OLDER SPOROPHYTE 203

twenty xylem rays, only the outer tracheids being lignified. In the plant which was
examined by Miss Shove only the earth roots were found, and these, instead of
having only five xylems as Russow asserts, had from ten to thirteen and the xylem
elements were entirely lignihed. The probabilities are that there is no sharp line
to be drawn between the aerial roots and the earth roots. Figure 183 shows a sec-
tion of a root from the base of a small plant from Australia, in which there were
fourteen xylem masses. As will be seen, there ts the same circle of large mucilage
ducts and the tannin cells that are found in the root of Marattia, which it very
closely resembles. Root hairs are nearly or quite absent, in which respect these
resemble the older roots of other Marattiaceee. In two cases Miss Shove found a
dichotomous branching of the root. ‘This, while probably anomalous, is interesting,
as it recalls the method of branching in the roots of Ophroglossum.

ARCHANGIOPTERIS.

The genus Archangropterts, with a single species, 4. henry: Christ and Giesen-
hagen, 1 is at present known only from a single locality in southern China. Arch-
angiopteris in habit resembles a large Danea. The leaves, which reach a length of

Fic. 183.—Angzopterts.

A. Section of a large root. m, mucilage ducts. X14.
B. Part of the central cylinder of the root. ez, endodermis. X70.

about a meter, have from seven to twelve leaflets, much like those of Danaa elliptica,
both in form and venation. The stalk of each leaflet 1s swollen in a manner that
suggests the nodular swellings in the petiole of Danaa elli ptica (fig. 184).

The only account of the structure of the plant is that of Gwynne-Vaughn
(Gwynne-Vaughn 2), but as he had only a fragment of a stem he was not able to
make a complete study of the vascular system. To judge from the fragment of the
stem which he examined, the leaves seem to be arranged spirally ae the stem
is probably radial in structure. The general structure of the leaf base seems to be
most like that of Kaulfussta. The ai trace consists of only two vascular strands,
which divide up later into several (eight or nine) separate strands, arranged at the
base of the leaf in a horseshoe curve, quite like that of Kaulfussia. The arrange-
ment of the vascular system of the stipules 1 is probably the same as in the ora
Marattiacee. The structure of the stem is also apparently very much like that
of Kaulfussra, a section showing only one circle of bundles with a single central
strand. The root, which is ike that of the other Marattiacew, has from seven to
ten xylem rays.

204 THE MARATTIALES

MACROGLOSSUM.

This represents a new genus of Marattiacew, the one species of which, M. alida
Copeland, has recently been described (Copeland 1). It isa large fern from Borneo,
and is evidently related to Angropteris, from which it differs mainly in its simply
pinnate leaves, which may reach a length of about 3 meters (see Copeland 1, plate V).

TISSUES OF THE MARATTIACE#.

There are often present upon the leaf bases of the Marattiacee peculiar lenticel-
like structures to which German writers have given the name “Staubgribchen.”
These arise beneath the stomata, and form small cavities whose peripheral cells
become detached and dried up, forming a dust-like powder.

Rod-shaped bodies, mainly composed of cal-
cium pectate, are of common occurrence in the
intercellular spaces of the tissues of the Marat-
tiacee. Siliceous deposits and crystals of calcium
oxalate have also been observed in Angropterts
(see Bitter 1).

The elements of the vascular bundles are much
like those in the bundles of the ordinary ferns. The
tracheary tissue is composed mainly of scalariform
elements, and the sieve tubes have numerous lateral
sieve plates, like those of the other ferns. Hill and
Farmer have noted a slight secondary formation
of wood in Angiopteris, somewhat similar to but
much less marked than that in the stem of Botrych-
ium virginianum (see Hill 1, Farmer 3).

THE SPOROPHYLL OF THE MARATTIACE#.

The Marattiacee differ most strikingly from
the Ophioglossace in the character of the sporo-
phylls. In all of the living Marattiacee the sporan-
gia or synangia are borne upon the lower surface Fic. 184.—Archangiopteris henryi (after Christ
of the leaves, which usually are not at all different and Gicseakingen).
from the sterile ones. In Danea (fig. 189) the sporophylls are decidedly contracted
and the very large synangia almost completely cover the lower surface of the leaflets,
but in the other genera the sporophyll is not at all contracted and much the greater
part of the leaf surface is free (figs. 182, 184, 185, 188).

Kaulfussia (fig. 188) differs most from the other genera, the very peculiar cir-
cular or rarely oval synangia being scattered apparently without any definite order
over the whole lower surface of the leaf. In Dana the elongated synangia, which
lie over the veins, extending from the midrib nearly to the margin of the leaflet, are
crowded so that they leave very little of the surface free. In Marattia and Angiop-
teris the synangia lie over the veins as they do in Danea, but they are very much
shorter and are formed near the margin of the leaflet, within which they form a
single line which occupies only a very small part of the leaf. Archangropterts, except
that the synangia are very much longer, agrees closely with Angropterts.

No proper indusium is present in the Marattiacea, although very commonly
about the base of the synangium there are found a few hairs or scales which have
sometimes been considered to represent an indusium. In Danea there is a growth
of tissue between the elongated synangia, which grows up into a sort of ridge, the

THE OLDER SPOROPHYTE 205

top of which is expanded so that it overarches the synangia. ‘This ridge in section
appears T-shape. Whether this growth of leaf tissue between the synangia in
Danea is to be considered as an adnan may be questioned. It appears to be
very similar in structure to the oblong cavity or fovea, within which is sunk the not
very dissimilar synangium of Jsoétes (fig. 189, B).

THE SPORANGIUM OF THE MARATTIACE®

In Angiopteris and Archangiopteris there are formed separate sporangia not
very unlike those found in Botrychium or Helminthostachys, but in all the other
genera the sporangia are fused into a synangium which might be compared with
the spike of Ophioglossum. The synangium in Danea pla ee may reach a
length of over 3 centimeters and contain upward of roo loculi. The first study of
the development was made upon Marattia by Luerssen (Luerssen 3). According
to his statement, the differenti-
ation of the synangium begins
while the leaf is still very small
and rolled up between the stip-
ules. The tissue about a vein
begins to develop into an elevated
cushion following the vein. Upon
this receptacle there are devel-
oped two parallel ridges of tissue,
separated by a cleft. These two
ridges later grow upward and
meet above, so that their edges
completely close up the cleft,
which no longer shows from the
outside. In each half of this syn-
angium, very much as is the case

in the sporangial spike of Ophio- fh OOD

glossum, there are developed sep- ee 6)

arate archesporial groups corre- 00
c

sponding to the separate cham-
bers that are found in the fully A. Leaf from a young sporophyte. st, stipules. 2.
developed synangium. Luerssen B. Leaflet with synangia. x4.

states that the whole process takes oor once lvee Her Glas yaaa Kee

about six months for its completion (fg. 186).

In Angropterts (fig. 187) the development of the sporangium begins at a much
later period, when the leaf is almost completely developed. ‘The sporangia here are
arranged in an oblong group or sorus, which corresponds to the synangium in Marat-
tia. The formation of the sorus begins, according to Goebel, as an oblong depression
above a young vein, and about this depression there is formed a circle of short hairs
which are sometimes supposed to represent an indusium. ‘Two ridges corresponding
to those found in the young synangium of Marattia are formed, but upon these the
young sporangia develop separately, very much as they do in Botrychium.

Goebel states that the archesporium in Angiopteris can be traced back to a
single hypodermal cell. This cell divides repeatedly but apparently without any
definite order, and there is finally formed a large mass of sporogenous tissue, each
cell of which gives rise in the usual way to four : spores. The cells about the arche-
sporium develop the tapetum. Goebel states that these tapetal cells are destroyed
before the division of the spore mother cells, but I have found that this is not the

Fic. 185.—Maraitia douglasit.

206 THE MARATTIALES

case and that the tapetal cells persist until the division of the spores is complete.
Bower has confirmed this statement and found that the same condition of things
obtains in the other genera.

The most complete account of the development of the sporangium is that of
Bower (Bower 6), who has studied the development in all of the genera except
Archangiopterts. Except for the difference in form, there is no essential difference
in the development of the sporangia in Kaulfuss:a and Danea from that found in
Marattia. In Danewa, however, the individuality of the loculi of the synangium
is less clear than in the other genera. Very often Bower found that the arche-
sporium became divided more or less completely by parts of the sterile tissue, some-
what in the same fashion that the so-called “trabeculae” are formed in J soétes.
In Danaea, moreover, the synangium from the first is solid, and the cleft which is
present in the young synangium of Marattia is absent. In Kaulfussia the develop-
ment of the synangium differs in that a single circular ridge is formed instead of the

6) 2
e, q
pesse )
& 2,
HR 3 sy nay, LA
S22

Fic. 186.

A. Section of a young synangium of Marattia fraxinea. X225.
B. Loculus from an older synangium. x, the tapetum (after Bower). X112

two parallel ones found in Marattia, and the loculi or chambers of the synangium
are thus arranged in a circle around a central pit-like depression. Bower states
that the sporogenous tissue of each loculus in all the forms he examined can usually
be traced to a single mother cell. He also found that the tapetum always arises
from the cells adjacent to the archesporium, and that normally all of the sporogenous
tissue develops into spores. In these respects the Marattiacee closely resemble
Helminthostachys and Botrychium.

In Danea and Kaulfussia there is no mechanical tissue representing the annulus
found in the more specialized ferns. The dehiscence of the sporangium in these
forms is brought about merely by a shrinking of the cells on either side of the slit by
means of which each loculus opens. This slit is very short in Danea and may finally
appear as a circular pore, but it is not essentially different from the more elongated
slit found in Kaulfussta and Marattia. In the latter there is developed, in the outer
tissues of the synangium, mechanical tissue which causes the two halves of the
synangium to separate, very much like the two covers of a book, and the elongated
slit from each loculus opens into this space between the widely separated halves of
the synangium.

THE OLDER SPOROPHYTE 207

The dehiscence of the individual loculi is affected by the contraction of the
thinner-walled cells surrounded by firmer tissue. The sporangium of Angropteris is
undoubtedly a more specialized structure than the synangium of the other Maratti-
acee. In Angiopterts each individual sporangium has the wall on the outer side
much thicker than that on the inner one, and the superficial cells have their walls
much thickened. The inner wall ts sometimes composed of but one layer of cells
outside of the tapetum, but more commonly there are one or two layers of cells
between the tapetum and the epidermis. Near the top of the sporangium on its
outer side there is a transverse band of cells with thicker walls, and these constitute
a rudimentary annulus very much like that found in the Osmundacee. By the
contraction of this thickened annulus the longitudinal slit on the inner face of the
sporangium is made to open widely at maturity. “The number of spores produced
in each loculus, according to Bower, is approximately 1,750 for Danea, 7,500 for
Kaulfussia, 2,500 for Marattia, and 1,450 for Angtopterts.

Which type of sporangium in the Marattiacea is the more primitive ts very
difficult to say, as both the free sporangium like that of Angropteris and the compact
synangium like that of Marattia
and Dee are of about equal
antiquity, so far as the geological
record goes. It must Be remem-
bered that the living Marattiaceze
are almost certainly merely a few
isolated fragments of a once large
group, and it is by no means
necessary to assume that the spo-
rangia of the living forms must
necessarily all conform to a com-
mon primitive type. It seems
quite as likely that the free spo-
rangia, like those of Angiopterts,
may have originated directly from
some ancient prototype which
Bie Hee gcd ios resembled, perhaps, forms like

A, B, secti ( i Goebel). s ium.
A, B, sections of young sporangia (after | oebel). C, an older sporangium Boir yc aur oT Elelminthostachvs Vs,
r, the annulus; 7, the persistent tapetum. X75.

while the genera with the soled
synangium like Danea may have come from forms with completely united spo-
rangia like Ophioglossum.

It appears from a study of the most ancient ferns that these had dimorphic
leaves, the sporophyll probably resembling the fertile spikes of Botrychium or the
fertile leaf segments of Osmunda. How the modern Marattiacee originated from
forms of this type is not by any means clear. The development in Helminthostachys
of sterile leaf-like lobes associated with the sporangia may perhaps afford a clew to
the method of sterilization by which the sporangiophores of some type allied to the
Ophioglossacee may gradually have developed sterile green leaf segments, bearing
upon their lower surface sporangia or synangia like those of the modern Marattiacez.
These sterile segments found in Helminthostachys are occasionally strikingly leaf-
like, and as the groups of sporangia in Helminthostachys are sometimes united into
small synangia, the development of similar sy nangia upon the lower surface of such
green sterile segments of the sporangiophore is quite conceivable.

Another explanation might be the coalescence of the fertile and the sterile parts

of a sporophyll like that found in the Ophioglossace, but the fact that the spo-

208 THE MARATTIALES

rangiophore in all of the living Ophioglossacez is adaxial, while in the Marattiacew
the synangia are abaxial, is a serious objection to such a hypothesis; and the most
plausible explanation at present seems to be that of a progressive sterilization of
part of the sporophyll itself and the expansion of the sterile tissue into the broad
lamina of the leaf bearing the separated sporangia or synangia upon its lower surface.

It must be admitted that the difference between the sporophylls of the existing
Marattiacew and those of the Ophioglossacew is very great, and the leaves of the
former, superficially at least, are much more like those of the leptosporangiate ferns;
but the sporangia themselves are very similar in their development to those of the

Fic. 188.
A. Lower surface of a sporophyll of Kau/fussia, showing C, D. Cross-sections of a synangium.
circular synangia. X1.5. C, Near top, showing openings of loculi.
B. Median section of a synangium. X12. D. Near middle. X12.

Ophioglossacez, and offer no obstacle to the assumption of a fairly close relationship
between the Ophioglossacez and the Marattiacea, which is indicated by the history
of the development of the gametophyte, and the vegetative organs and tissues of the
sporophyte. Perhaps the most marked difference between the tissues of the Marat-
tiacee and the Ophtoglossacee is the prevalence of the mucilage ducts in the tissues
of Marattiacez, but these arise rather late in the history of the sporophyte, and it is

COCCI)

SU Gesiines

Fic. 189.—Danea jamatcensis.

A. Base of a fertile leaflet, showing synangia, sp. X2.
B. Transverse sections of three synangia. X12.
C. Horizontal section of a synangium.

significant that they are less developed in the presumably more primitive Kaulfussia
than they are in the more specialized types like Angopteris. Another difference is
the development of sclerenchyma, which is quite absent from the Ophioglossacex;
but this again is also quite absent from Kaulfussia, which, on the whole, must be
considered to be the most primitive of the living Marattiacee and also the form
which most closely approaches the Ophioglossacez.

Part III. THE ORIGIN AND RELATIONSHIPS OF
THE EUSPORANGIATA.

The eusporangiate ferns as they now exist represent but a few isolated fragments
of what in earlier geologic time was presumably a very much larger and more con-
nected group. As the geological history of these forms is very far from clear (this
being especially true of the Ophioglossacez), we are, perforce, dependent mainly
upon a comparative study of the few existing types for information concerning their
relationships. In the foregoing pages an endeavor has been made to trace the de-
velopment of these forms, both in their gametophytic and early sporophytic stages,
and the result of these studies has been to confirm the belief that a real genetic
relationship exists between the Marattiacee and the Ophioglossacezx.

While the three genera of the Ophioglossacez differ in certain particulars from
each other, there is no question as to their being comparatively closely related, and
the same is true of the different genera of the Marattiacee, although perhaps the
differences here are somewhat greater than in the Ophioglossacez.

It has been assumed in these studies that the sporophyte of the ferns is the
result of a progressive specialization of the sporogonium of some form allied to the
Bryophytes, though it is highly improbable that any of the existing Bryophytes are
directly related to this progenitor of the primitive ferns. No attempt will be made
here to discuss the reasons for accepting the “antithetic” theory of the alternation
of generations, rather than the homologous theory. These reasons have been set
forth at length elsewhere.

It is hopeless to expect that any satisfactory fossil traces will be found of these
predecessors of the true ferns. The fern type is exceedingly ancient, but it must
have been preceded by simpler forms connecting it with some bryophytic type.
These forms, as well as the earlier true Pteridophytes, were almost certainly plants of
small size and delicate texture, probably not very unlike some of the small and
delicate species of Ophioglossum. Such plants, composed entirely of soft, perish-
able tissues, could hardly be expected to leave recognizable fossil traces, and their
absence from the ancient Paleozoic rocks is not to be wondered at.

There still exist, however, among the Bryophytes, certain forms which, if they
are not directly related to the eusporangiate ferns, nevertheless show many striking
similarities in structure, which help to explain at least what may very well have been
the character of the liverwort-like ancestors from which the ferns are descended.
Among the living Bryophytes, as is well known, an interesting series of types may be
traced, showing ne gradual increase in the importance of the neutral generation—
the sporophyte_—starting as little more than a mass of spores, finally by a progressive
sterilization of what was originally sporogenous tissue, and an accompanying spectial-
ization of the sterile tissues thus formed, attaining a condition of almost complete
independence. The importance of this process of sterilization of potentially sporo-
genous tissue, has been especially clearly expounded in the works of Professor Bower.

In two classes, the true mosses or Musci and the horned liverworts or Antho-
cerotes, the sporophyte continues its growth for several months and develops an
elaborate system of green, assimilative tissue, quite comparable to that found in
the vascular plants. The spore-producing function is correspondingly subordinated
and the spore formation is delayed until a late period in the life of the sporophyte.

14 209

= Vpn =

910 ORIGIN AND RELATIONSHIPS OF THE EUSPORANGIATAE

The large, green sporophyte, however (fig. 190, 4, sp), never attains complete inde-
pendence, as no proper root is developed and it is dependent for its water supply
upon the gametophyte.

In all of the Eusporangiates, the embryo is much later in developing its organs
than in the Leptosporangiates, and thus resembles the Bryophytes; moreover, the
embryo reaches a very much larger size before it attains its independence. Even
after the young sporophyte has developed several roots and leaves, it may still

Fic. 190.

A. Gametophyte of Anthoceros sp. with the large
sporophyte, sp, attached to it. Upper part
of sporophyte is split into valves which allow
the escape of spores.

B, C. Two gametophytes of Marattia douglasii, with
attached sporophyte. Sporophyte emerges
upon upper side of gametophyte, very much
as in Anthoceros, but a root, r, is developed
which penetrates lower side of gametophyte
and connects the young sporophyte with the
earth. g, gametophyte; sp, sporophyte;
/, first leaf; r, primary root.

Maintain its connection with the gametophyte and be to a certain extent dependent
upon it in a way which forcibly recalls the relation of gametophyte and sporophyte
in the mosses. This condition, which furnishes a very strong argument in favor of
the primitive nature of the Eusporangiates when compared with the Leptosporan-
giates, is especially pronounced among the Ophioglossacez, where it may even go so
far that spores are developed before the connection of gametophyte and sporophyte
is finally sundered.

. In the true mosses the sporophyte is exceedingly specialized and shows but a
very remote resemblance to that of the Pteridophytes. In Anthoceros, however, the

Fic. 191.

Diagrams which show the similarity in form of the very
young sporophyte in Anthoceros,A,and Ophioglossum,
B. In the former the upper portion becomes an elong-
ated capsule within which spores are produced. The
shaded portion shows layer of sporogenous tissue sur-
rounding central sterile tissue or columella. The
zone, m, between capsule and foot, f, is composed of
meristematic tissue. In Ophioglossum the upper part
of the young sporophyte forms the primary leaf, or
cotyledon, cot, which is not sporogenous. The colum-
ella of Anthoceros is replaced by the axial vascular
bundle, v.b. At the junction of the cotyledon and
foot arises the primary root, r, which finally penetrates
the foot and enters the ground.

&
~

most highly developed of the horned liverworts, there are a number of very significant
structural details that are very strongly reminiscent of the young sporophyte of
Ophioglossum moluccanum. In both of these forms the young embryo has a very
large foot and a conical upper region (fig. 191). This upper portion in Ophioglossum
develops into the cotyledon; in Anthoceros, into the spore-bearing part of the sporo-
phyte. Above the foot in Anthoceros there is developed a zone of meristematic
tissue by means of which new cells are added to the base of the growing sporo-

“a

ORIGIN AND RELATIONSHIPS OF THE EUSPORANGIATAE PAUL

phyte, and in Ophioglossum much the same thing occurs in the cotyledon, although
at first this grows from a single apical cell. It is probable that in the ancestors of the
Ophioglossacee this upper conical portion of the embryo was developed directly
into a spore-bearing organ. ‘There is, however, a marked difference which soon
appears, viz, the development of a true root in Ophioglossum. This root, pushing
down through the foot, penetrates the lower side of the gametophyte and places the
young sporophyte directly into communication with the water supply from the earth,
and thus the latter becomes entirely independent. Were the large sporophyte of
Anthoceros to develop a similar root from the basal meristem, it also would become
entirely self-supporting. Indeed, so marked are the resemblances in the early stage of
development that they make the inference almost irresistible that the Ophioglossacez
must have descended from some simpler forms whose sporophyte bore a strong
resemblance to Anthoceros. This “pro-Ophioglossum,” if we may call it so, pre-
sumably produced spores upon the first leaf, instead of its being a sterile cotyle-
don as in the existing forms. From a study of the development of the sporophyte

Fic. 192.—Comparison of sexual organs in Anthocerotacee and Marattia.

po

. Longitudinal section of the thallus of Anthoceros pearsont Howe, showing an antheridium mother cell,
with the superimposed cover cell (d).

. An older antheridium within a cavity covered by a double layer of cover cells.

- Young archegonium of Megaceros tjibodensis Campbell, a form closely related to Anthoceros.

. Sections of young antheridia of Marattia douglasti Baker. The inner cell divides at once into the sperm
cells, and the cover remains single-layered. d, the cover.

- Young archegonia of Marattia douglasii. b, the basal cells of the archegonium; d, neck.

=m DpOw

-in O. moluccanum, it may be inferred that this ancestral form had no stem, but
consisted simply of this spore-bearing leaf and a root. The sporangia were presum-
ably simpler than in the existing forms of Ophioglossum, and perhaps intermediate
in character between such sporangia as those of the smaller species of Ophioglossum
and the imperfectly segregated spore groups which occur in the Anthocerotes.

Not only does the sporophyte of Anthoceros show important resemblances to
that of Ophioglossum, but the development of the sexual organs also shows striking
analogies. “The archegonium, unlike that of other Bryophytes, is sunk below the
surface in much the same fashion as that of the eusporangiate ferns, and the short
neck of the archegonium in the latter is probably to be compared to the four terminal
neck cells which may occur in the Anthocerotes (fig. 192). The endogenous anther-
idia of the Anthocerotes also may perhaps be compared to the sunken antheridia of
the eusporangiate ferns, and in their early stages the resemblances are very close.

AW ORIGIN AND RELATIONSHIPS OF THE EUSPORANGIATAE

The most marked difference in the character of the reproductive organs is the
spermatozoid. ‘The spermatozoids in the Eusporangiates, especially in Ophio-
glossum, are very large and possess numerous cilia, while in Anthoceros they are
minute and have but two cilia, like the other Bryophytes. This is perhaps the strong-
est reason for assuming that there is not a direct connection between the Anthoce-
rotes and the Ophioglossacea; but both gametophyte and sporophyte have so many
points in common that it may be pretty safely assumed that the progenitors of the
Ophioglossacew were not very different, in appearance at least, from the living dn-
thoceros. Whether the differences in the spermatozoid are secondary remains to be
seen, but in view of the extraordinary constancy of the form of the spermatozoids
in all of the main groups of the Archegoniates, one would certainly expect that large
multiciliate spermatozoids would be founds in the ancestors of the l-usporangiates,
supposing these should ever be discovered.

There is no question that the subterranean prothallium of the Ophioglossacex
is a secondary condition, derived from some green gametophyte, probably very much
like that of the Marattiacew. Not only has the chlorophyll been lost, but in Ophio-
glossum and Helminthostachys the dorsiventral form of the gametophyte has been
replaced by a radially sy mmetrical thallus. » While this may be partially explained
as the result of the absence of light, it must be remembered that the equally sub-
terranean prothallium of Botrychium is dorsiventral, although the reproductive
organs are borne upon the dorsal surface and not upon the ventral one, as they are
in most ferns. Whether this position of the reproductive organs is the result of the
conditions of growth or whether it indicates that the green gametophyte from which
this saprophytic underground form is descended also bore the reproductive organs
dorsally, as most ltverworts do, can only be conjectured. In the Marattiacez
antheridia are not uncommon upon the dorsal surface, and according to Jonkmann
archegonia also may occur dorsally... Whether this is normal or is the result of unusual
light conditions was apparently not investigated. The formation of archegonia in the
ordinary ferns may be induced upon the dorsal side of the prothallium, provided
it is illuminated from below. If the illumination is equal on both sides, archegonia
will develop both on the ventralfand dorsal surface.

Of the investigated species of Ophioglossum, O. moluccanum and the nearly
related and perhaps identical O. pendunculosum probably represent the most primi-
tive type. In these species there may be a feeble development of chlorophyll in the

gametophyte under certain conditions and the saprophytic habit is much less pro-
nounced than it is in the other species of Ophioglossum and Botrychium.,

The development of an endotropic mycorrhiza in the prothallium of the
Marattiacee is an interesting suggestion as to the probable beginning of the sapro-
phytic habit which characterizes the gametophyte of the Ophioglossacee. There
seems to be good reason to suppose that the peculiar type of symbiosis, which is
developed so ‘highly i in the Ophioglossacew, began by the development of a fungus
associate in some green gametophyte like that of the Marattiacez.

The reproductive organs of the Ophioglossacez and Marattiacee are very
similar indeed. It is probable that the short-necked archegonium found in the
Marattiacee and in Ophroglossum is more primitive than the long-necked arche-
gonium of Botrychtum or Helminthostachys. This conclusion is based upon the
assumption that the four-necked archegonium of the ferns is a development of the
four terminal cells in the neck of the? Bryophyte archegonium, Anthoceros most
nearly approaching this hypothetical ancestral type. This being the case, the forms
with the shortest neck would most nearly resemble this assumed ancestral type.

ORIGIN AND RELATIONSHIPS OF THE EUSPORANGIATAE 218

The question of the canal cells is a puzzling one. In the Marattiacez, with the
exception of Dana, two neck canal cells, or at any rate two nuclei, are present and
the ventral canal cell is conspicuous. In Danea, however, the canal cells are very
much less perfectly developed, the ventral canal cells especially being exceedingly
dificult to demonstrate. In the latter respect Danea shows a remarkable resem-
blance to the Ophtoglossacez, especially to Ophioglossum, where the ventral canal
cell is equally difhcult to demonstrate. This apparent degeneration of the ventral
canal cell is probably secondary, as all of the Bryophytes and the other Pteridophytes
have the ventral canal cell conspicuous.

The antheridium in all of the Marattiacez is almost exactly like that of Ophio-
glossum, while Botrychium and Helminthostachys differ in having the outer wall of
the antheridium more or less completely two-layered. If the antheridium is derived
from a type like that of Anthoceros (fig. 192), where the antheridial cavity is covered
by a double layer of cells, it would seem that Botrychium and Helmintho stachys are
more primitive than Ophioglossum or the Marattiacez in this respect.

Of the Eusporangiates, there is no question that the type of embryo found in
Ophioglossum moluccanum comes the nearest to the assumed ancestral form. This
hypothetical pro-fern may be assumed to have developed simply a spore-bearing
organ or sporangiophore, perhaps more or less leaf-like, and a root developed from
the inner part of the massive foot in the same way that the root actually does develop
in the embryo of the Marattiacee and Ophioglossum moluccanum.. xcept that the
cotyledon of O. moluccanum is sterile, the young sporophyte in this species is actually
like this hypothetical type, viz, it is composed simply of root and leaf. Itis probable
that the fertile spike of Ophioglossum is not unlike the primitive sporangiophore,
and the ancestral form presumably developed such a spike-like sporangiophore from
the first, the sterile lamina being a secondary structure arising perhaps from a basal
meristem, like that found in the sporophyte of Anthoceros. The early development
of the spores in the Ophtoglossacez is a further indication of their primitive nature.

~The monophyllous condition which prevails among the Ophioglossacee must
also be regarded not as a secondary condition but as a primitive one, and a study of
the development of the sporophyte lends no support to the theory that we have to
do with a reduced strobilus. “Of the Marattiacez, Kaulfussia normally approaches
the monophyllous condition more closely than any other genus.» The older plants,
as a rule, have only two or three leaves expanded at one time and there may fre-
quently be but one. In strong contrast with this is the dense crown of leaves found
in Marattia and Angropteris, although even in these forms the number of leaves is
less than it is in the majority of leptosporangiate ferns. he tendency to the mono-
phyllous condition is shown in the younger plants of Marattia, developed from the
buds on the old leaf bases, where, as a rule, only one leaf is expanded at a time.

The young sporophyte of O. moluccanum has no stem. Without exception, for
a considerable time at least, the vascular system of the sporophyte is composed
exclusively of tissue belonging to the leaves and roots, the stem apex playing no
part in the building up of the vascular skeleton. The theory that there is a special
stele belonging to the stem, of which the leaf traces and the root traces are sub-
sidiary structures, is not borne out by a detailed study of the evolution of the vascular
system in either the Marattiaceew or Ophioglossacee. In all of these that I have
examined the vascular system begins as a single strand common to the primary
leaf (or cotyledon) and the primary root, and the more complicated vascular system
of the older stem for a very considerable period is built up exclusively by additions
of new leaf traces or root steles. ‘This condition is permanent in the Ophioglos-

214 ORIGIN AND RELATIONSHIPS OF THE EUSPORANGIATAE

sacew. In the Marattiacea small cauline bundles (commissural bundles) may be
developed at later stages, but these are insignificant compared with the complex of
united leaf traces.

The antithetic theory of alternation implies that the sporophylls are older
structures than the sterile leaves, and those ferns in which the sporogenous function
of the sporophylls 1 is most pronounced may be assumed, other things being equal,
to be the most primitive. In this respect, as well as in the usually monophyllous
condition, the Ophioglossacez are distinctly more primitive than the Marattiacez.
The sporangiophore or fertile leaf segment is a practically independent structure,
being differentiated at an extremely early period in the development of the leaf.
In the Marattiacez the sporangia are subordinate and the leaves upon which they
are borne usually differ in no respect from the sterile leaves. The most marked
exception to this is Dana, in which the sporophylls differ decidedly from the sterile
leaves and the synangia are much larger than those of the other genera, although
the leaves themselves are usually smaller.

Bower thinks that the circular synangium of Kaulfussia is the most primitive
type among the existing Marattiacea, but there is some reason to doubt the sound-
ness of this conclusion; at any rate, on theoretical grounds, the large synangia and
contracted sporophylls of Danea must be assumed to be more primitive than the
type of leaf found in Kaulfussra. In regard to the character of the sporophylls,
therefore, none of the living Marattiacee can be regarded as being very primitive.
All of the oldest fern fossils show the sporangia to be borne upon special leaves or
leaf segments, in which the lamina is nearly or quite absent (Scott 1, Bower 9).
In this respect, therefore, these ancient fossil ferns were more like the Ophiogloss-
acez than like the Marattiacew, although their sporangia came nearer to the type
of Marattiacew. It is by no means impossible that these oldest ferns, e. g., the
Botryopteridex, were related to the Ophioglossacez.

The single apical cell found in the stem apex throughout the life of the sporo-
phyte in Ophioglossum 1 is probably a more primitive condition than the group of
cells found in Angropterts. It still remains to be seen whether the single apical cell
found in the other Marattiacez in their early stages is persistent throughout life or
is replaced, as in the roots, by a group of initial cells.

The single axial strand of collateral structure throughout cotyledon and root
may be taken as the starting point for two types of vascular skeleton which have
arisen from it. The first is that of Ophioglossum, where, with the development of
the new leaves, there is built up the wide-meshed cylindrical network or dictyostele,
composed of single collateral leaf traces. A further development of the same type
results in the much more complicated dictyosteles of the Marattiacea, where, more-
over, the collateral bundles are replaced by concentric ones. This greater com-
plexity i is due primarily to the much larger leaves of the Marattiacez, in which the
leaf traces are compound. In the earlier stages of these forms, however, we have
seen that the young leaf traces are single and the structure of the vascular skeleton
exactly as it is in Ophioglossum. Of the Marattiacee, Kaulfussia more nearly
retains this primitive condition than the other genera and next to this comes Danea,
while further removed from the primitive type is the exceedingly complex skeleton
found in the massive stem of Angiopteris. The concentric bundles, characteristic
of the Marattiacee, are presumably of secondary origin and we find that in the
early bundles, especially of Dana, a true collateral structure is present.

The second type of skeleton is that found in Botrychtum and Helminthostachys.
This is a solid, hollow cylinder with inconspicuous leaf gaps, resulting from the
union of the broad leaf traces, which fuse completely to form this hollow stele. That

ORIGIN AND RELATIONSHIPS OF THE EUSPORANGIATAE 215

the cylindrical bundle, or siphonostele, is not due to the formation of a pith within
a protostele is clearly shown by the study of the development of the bundle in the
young sporophyte of Botrychium, where it can easily be seen that the component
bundles are separate at first, and that the pith, so-called, of the siphonostele 1s merely
a portion of the ground tissue that is included between them, and which later be-
comes entirely separated from the cortical tissue. A similar condition of things may
be found in tracing the development of the vascular cylinder in the young stem of
Helminthostachys. The development of the young bundles in Angropteris is more
like Botrychtum than Ophioglossum, and this, in connection with the separate
sporangia that occur in Angropteris, suggests that perhaps the type of the Marat-
tiacee represented by Angropteris may have originated independently from forms
like Helminthostachys, instead of having had the same origin as those forms in
which true synangia are developed.

The essential similarity of the leaf structures throughout the Ophioglossacez
is sufficiently clear, and the steps in the increasing complexity of the sporophyll can
be easily traced in existing forms, ranging from the undivided fertile and sterile
segments of Ophioglossum to the decompound leaves and much-branched panicle
of Botrychium. Helminthostachys is much the most aberrant of the Ophioglossacez
and in many respects shows a marked resemblance to the Marattiacee. ‘The form
and venation of the leaves strongly recall Danea or Angiopteris, except that the
leaves are not pinnately divided, in which respect they closely resemble Botrychium.
It must be remembered, however, that the ternate form of leaf characteristic of
Botrychium and Helminthostachys is very generally met with in the early stages of
the sporophyte in the Marattiacee. The anatomy of the leaf in Helminthostachys
very closely resembles that of the Marattiacez, there being a well-developed palisade
layer in the mesophyll, a character which is either wanting entirely or very imper-
fectly developed in Botrychium.

The leaves of the Marattiacex, except in Kaulfussra, in their form and in the
circinate coiling of the young leaves, suggest a relationship with the leptosporangi-
ate ferns rather than with the Ophioglossacee. However, the larger species of
Botrychitum and Helminthostachys show an approach to this circinate form of the
young leaf, this being especially conspicuous in the young sporophylls of Botrychium
virginianum. With the exception of Kaulfussia, the general form and venation
are alike in all the Marattiacee and have their nearest analogy in Helminthostachys.
There seems no reason to assume that the stipular sheath in the Marattiacez is dif-
ferent in its nature from that of the Ophioglossacex, especially Helminthostachys
and Botrychium. The ternate form of the leaf may be persistent in Kaulfussza,
where, however, the venation is more like that of Ophioglossum. Whether this
occurrence of both reticulate and pinnate venation in the two families is a case of
parallel development, or whether it indicates the comnection of the families at dif-
ferent points, it is at present impossible to say.

In the structure of the roots the Marattiacee find their nearest ally in Hel-
minthostachys, where the number of the xylem rays, four to seven, equals that of
Kaulfussia, which has the simplest structure among the Marattiacee, and, as we
have seen, probably on the whole is most nearly related to them. Helmuinthostachys
also resembles the Marattiacee in the character of the apical growth of the root,
where, although there is a single apical cell, such as occurs in the young roots of the
Marattiacez, its form is more like that of the Marattiaceze than it is like that of
Botrychium. ‘The endophyte which occurs in the older roots of the Ophioglossacez, as
well as in the primary one, | have not found in the older roots of the Marattiacez, at

least not as a regular thing, although it seems to be always present in the primary root.

216 ORIGIN AND RELATIONSHIPS OF THE EUSPORANGIATAE

The Ophioglossacew and Marattiacee are alike in the absence of any mechan-
ical tissues in the cortex of the stem. Sclerenchyma, which is well developed in
the leaves of most of the Marattiacea, seems to be entirely wanting in all of the
Ophioglossacee, but the collenchyma which replaces sclerenchyma in certain
organs of the Marattiacew, and is the only form of mechanical tissue in K aulfussia,
is occasionally found in the Ophioglossacew. A notable case of this is the broad and
very conspicuous zone of collenchyma surrounding the root bundle in Ophioglossum
palmatum. The mucilage ducts so characteristic of Marattiacee are apparently
quite wanting in all of the Ophioglossacez, and the tannin sacs which are a nearly
constant feature in the Marattiacee are absent in Botrychium and Ophioglossum,
but occur in Helminthostachys.

In the general structure of the vascular bundles there are important resem-
blances. In both families the first-formed tracheids in the young sporophyte are
all of the short, reticulate form, and this is retained permanently in Ophioglossum,
but is replaced later by pitted tracheids in Helminthostachys and Botrychium.
Helminthostachys alone among the Ophioglossacew shows ‘spiral protoxylem ele-
ments like those found in the later bundles of the Marattiacez.

It is probable that the collateral bundles of Ophioglossum represent the prim-
itive type from which the concentric type found in the Marattiacez has been derived.
In Botrychium and Helminthostachys, while the collateral type of bundle is found
in the stem, in the petioles the bundles are concentric, as they are in the Marattiacez.
The collateral type of bundle reappears again in the early stages of the sporophyte
in Danea.

Angiopteris, which is probably the most specialized of the living Marattiacez,

, has concentric bundles only.

CONCLUSION,

While the more specialized Marattiacee, like Marattia and Angropteris,
apparently differ very much from the Ophioglossacez, it appears from a study of
the development of these forms, as well as that of the simpler and presumably more
primitive genera Danea and Kaulfussia, that the most conspicuous differences are
of secondary rather than of primary importance, and the conclusion is justified that
the two families of the Eusporangiate really arose from the same primitive stock.
Of the Ophioglossacee, Helminthostachys is undoubtedly the form which, on the
whole, comes nearest to the Marattiacez, although Ophioglos sum is more like them
in the character of the reproductive organs and in the vascular skeleton of the
sporophyte. Ophioglossum also recalls Kaulfussia in the form and venation of
its leaves.

While the green gametophyte in the Marattiacee is undoubtedly a more
primitive structure than the saprophytic prothallium of the Ophioglossacex, the
sporophyte of the latter is certainly a more primitive one than that of the Marat-
tiacee. The monophyllous condition, the early development of the sporangia, and
the fact that the whole of the sporangiophore is spore-bearing, all point to this.

The way in which the sporophyll of the Marattiacee has been derived from a
type like that of the Ophioglossacez is not clear, and it is by no means certain that
all of the Marattiacee have been developed in the same way. The occurrence of
fossil forms with sporangia of the marattiaceous type grouped together—much like
the sporangia of Botrychium or Osmunda—suggests that such a condition might have
been preliminary to ‘the separation of the sporangia by the development of sterile
green tissue in the sporangiophore, such as sometimes occurs in Helminthostachys
The converse is not tenable unless we accept the view that the sterile leaf is an
older structure than the sporangiophore, a view which we believe is not warranted
by the facts. It has been suggested in a previous chapter that the sporophyll of the
Marattiacez might be nceomned for by a theory of concrescence of the sporangiophore
and sterile lamina in the Ophioglossacez. Ophioglo ssum palmatum, with the two
series of small sporangiophores and broad leaf lamina, is the form which comes
nearest to such a condition. A very serious objection to this view was mentioned,
however —the fact that the sporangiophore is an adaxial structure, whereas the
synangia of the Marattiacee are always abaxial in their position.

Comparing the eusporangiate ferns with the leptosporangiate, it is generally
conceded that the Osmundacee are the ferns which most closely approach the
Eusporangiate. The Osmundacee show points of resemblance to both the Ophio-
glossacee and Marattiacea, this being true both of the vegetative tissues and the
sporangia. In Osmunda the arrangement of the sporangia suggests Botrychium,
while in Todea the sporangia are borne upon the backs of the leaves, much as they
are in the Marattiacea. Bower has suggested that the Gleicheniacee, which are,
however, certainly allied to the Osmundaceze also, show certain suggestions of a

marattiaceous affinity, especially in the arrangement of the sporangia.

We may then briefly summarize our Eonchision as follows: From some form,
allied to the simpler existing species of Ophioglossum, the whole fern series is
descended. In this whole series the leaf is the predominant organ, the stem at first
being quite subordinate in importance. ‘This ancestral fern was monophyllous and
the leaf at first was a sporophyll, perhaps without any definite sterile segment.

217

218 CONCLUSION

From this central type presumably several lines diverged, of which only a few frag-
ments persist. One of these is seen in the different forms of Botrychium, to which
Helminthostachys is probably not very remotely allied. The whole of this series is
characterized by a subterranean gametophyte, and a more or less saprophytic habit
of the sporophyte is indicated by the development of a mycorrhiza in the roots.

The Marattiacea, as they now exist, probably do not represent a single un-
broken line of descent, and show strong evidences of a possible multiple derivation
from the earlier stock. The point of contact with the Ophioglossacez is probably
in the neighborhood of Helminthostachys, which, on the whole, is more like the
Marattiacee than are the other Ophioglossacez; but it is improbable that the solid
synangium, such as characterizes most of the Marattiacez, was derived from a
group of separated sporangia like those in Botrychium or Helminthostachys, and it is
more likely that they arose from a structure which resembled the spike of Ophio-
glossum. Angiopteris is, with little question, the most specialized of the living
Marattiacee and has probably departed further from the ancestral type than any
of the other forms, while Kaulfussta, on the other hand, is probably the most
primitive. On the whole the Marattiacee are nearer to the leptosporangiate ferns
than the Ophioglossacez are, and it is likely that the Leptosporangiates are directly
descended from some ancient fern forms, allied to the Marattiacez, but differing
from any of the existing types.

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~

Wb

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PLATE 1.

AnkwWh

10.
II-I4.

15.
16-20.

PLATE 2.

21-20.

PLATE 3.

EISt OF PEATEs.

Two spores of Ophioglossum moluccanum Schlecht, showing range in size. 500.

. Two-celled gametophyte of O. moluccanum.

. Athree-celled stage. sp, ruptured spore membrane.

. A four-celled stage seen from above.

. Two transverse optical sections of a four-celled gametophyte.

. Three-celled gametophyte of O. tntermedium Hk.
7-9-

Young gametophytes of O. pendulum L., showing mycorrhizal infection. m, mycorrhizal
filaments.

Adult gametophyte of O. moluccanum. X10. 1, basal tuber; 6, antheridia.

Gametophytes of O. pendulum. x 3. 6, adventitious buds; sp, young sporophyte.

Upper part of ripe antheridium of O. pendulum. X 275. 0, opercular cell.

Development of the spermatozoid in O. moluccanum. x 950. 51, blepharoplasts.

Spermatogenesis in Ophioglossum pendulum. 950. 21 shows spermatocyte before final
nuclear division, with two blepharoplasts, b/ ; 22, 23, nuclear spindle from side and pole;
24-29, development of spermatozoid; 1, nucleus of spermatozoid; ¢, cilia; v, protoplasmic
vesicle.

. Three stages in the development of the archegonium of O. pendulum. x 275. b, basal cell;

n', n°, neck canal cells.

. Venter of the archegonium, showing apparently a ventral canal cell, v; 1, one of the nuclei

of the neck canal cell. x 650.

. Spermatogenesis in B, virgintanum; 38-41, in Kaulfussia; 42, 43, in Danea. All x 950.
. Nearly ripe spermatozoids of Angropterts. x 950. n, nucleus; 6/, blepharoplast; c, cilia;

v, vesicle.

. Nearly ripe archegonium of Danea, showing apparent ventral canal cell, v.
. Recently fertilized egg-cells of Danza. sp, spermatozoid (?) within the egg-nucleus.

Ophioglossum moluccanum Schlecht.
Several types collected at Buitenzorg, Java, and referred to O. moluccanum Schlecht. There are

PLATE 4.

at least three species. Fig. 5 is the typical O. moluccanum. All figures about natural size.

A. Six plants of Ophtoglossum (Ophioderma) intermedtum Hk. reduced one-half. Collected at

Buitenzorg, Java.

B. Ophioglossum (Ophioderma) pendulum L., collected in the Hanwella Reserve Forest, Ceylon.

Pe:

Full-grown sporophytes of O. pendulum, much reduced. In 2 the sporangial spike, sp, is
forked.

3-6. Details of the sporophyll and sporangiophore.

PLATE 5.

Ophtoglossum (Chetroglossa) palmatum L., collected in Jamaica.

I.

The whole plant.

2, 3. Sporophylls. In 3 there is a single median spike.

PLATE 6.

A.1, Botrychtum obliquum Muhl.; 2, B. lunarta L.
B. B. virginianum (L.) Swz.

PLATE 7.

Botrychium stlatfoltum Pr. California.

223

224

Pate 8.

LIST OF PLATES

A. Young plant of Helminthostachys zeylanica (L.) Hk. Reduced about one-half.
B. Full-grown plant of Helminthostachys, reduced about two-thirds. Collected in the Hanwella

Reserve Forest, Ceylon.

PLATE 9.

A. 1, small plant of Danaea jenmani Underwood; 2, rhizome of the same species; 3, apex of sterile

leaf; 4, fertile leaf; 5, sterile leaf of D. jamatcensts Underwood.

B. 1, young plant of Dana elliptica Sm. (?); 2, sporophyll of D. jamaicensis; 3, 4, very young

plants of D. jamaicensis (?).
All specimens collected in Jamaica.

PLATE 10.
Adult sporophyte of Danaa elliptica. Jamaica.

PLATE 11,
Kauljussta escultfolia Bl.
1. Young plant showing the rhizome.
2. Sporophyll. Specimens collected near Buitenzorg, Java.

PLATE 12.
A. Marattia alata Swz.
1. Part of fertile leaf.
2. A single fertile pinna.
3. Fallen leaf-base with adventitious buds, k.
B. Marattta alata.
1. Leaf from young plant developed from an adventitious bud.
2, 3. Young sporophytes arising from fertilization.
All specimens from Jamaica.

PLATE 13.
Angtopteris evecta (Forst.) Hoffm.

1-3. Specimens from Australia; 4, 5, specimens from Peradeniya, Ceylon.
1, caudex of a small plant; 2, part of a sporophyll; 3, cross-section of the petiole of a full-grown
leaf; 4, young sporophyte arising from the prothallium; 5, single leaf from a similar sporo-

phyte.

|
|
|
,

ODUbwWrm —

CAMPBELL

. Two spores of O. moluccanum, showing range in size. X 500.
. Two-celled gametophyte of O. moluccanum.

. A three-celled stage. sp, ruptured spore membrane.

. A four-celled stage, seen from above.

. Two transverse optical sections of a four-celled gametophyte.

. Three-celled gametophyte of O. intermedium Hk.

. Young gametophytes of O. pendulum L., showing mycorrhizal

infection. m, mycorrhizal filaments.

PLATE 4

10. Adult gametophyte of O. moluccanum. X 10. 1, basal tuber;
& , antheridia.
11-14. Gametophytes of O. pendulum. 3. 5, adventitious buds;
sp, young sporophyte.
15. Upper part of ripe antheridium of O. pendulum. X 275.
; 0, opercular cell.
16-20. Development of the spermatozoid in O. moluccanum, X 950.
bl, blepharoplasts.

CAMPBELL

7

a

faamm 02010)
by UT AM fi

21-29. Spermatogenesis in Ophioglossum pendulum. X 950; 21 shows
spermatocyte before final nuclear division, with two
blepharoplasts, b/; 22, 23, nuclear spindle from side and
pole; 24-29, development of sper matozoid; n, nucleus of
spermatozoid ; c, cilia; v, protoplasmic vesicle.

30-32. Three stages in development of archegonium of O. pendulum.
X 275. 5b, basal cell; n7, n2, neck canal cells.

33. Venter of archegonium showing apparently a ventral canal cell, v.
n, one of the nuclei of the neck canal cell. X 650.

PLATE 2

34-37. Spermatogenesis in B. virginianum; 38-41, in Kaulfussia;
42, 43, in Danea. All X 950.
44. Nearly npe spermatozoids of Angiopteris. X 950. n, nucleus ;
bi, blepharoplast; c, cilia; v, vesicle.
45. Nearly ripe archegonium of Danea, showing apparent ventral

canal cell, v.
46-48. Recently fertilized egg-cells of Danea. sp, spermatozoid (?)

within the egg-nucleus.

“ezis Jeinjeu jnoqe soindy || “winuDzaNjOW *C) jes1dAy aul si ¢ “BLY

"satoads aay) jsea] ye are ary yt “WY22149g wnup oul °C 0} paliejai pue ‘eae ‘B1ozuaying ye pepe sed} [e1aAag

WP2|42G wnuvoonjow wnssojso1ydC)

CAMPBELL PLATE 4

A. Six plants of Ophioglossum (Ophioderma) intermedium Hk., reduced one-half. Collected
Buitenzorg, Java.

B. Ophioglossum (Ophioderma) pendulum L.. Collected in the Hanwella Reserve Forest, Ceylon.
1, 2. Full-grown sporophytes of O. pendulum, much reduced. In 2 the sporangial spike, sp, is forked.
3-6. Details of the sporophyll and sporangiophore.

at

Ophioglossum (Cheiroglossa) palmatum L. Collected in Jamaica.

1. The whole plant. 2, 3. Sporophylls; in 3 there is a single median spike.

a
eanert

PLATE 6

AMPBELL

“7 Dupuny “gl ‘7 SYRIA wanbygo wniyshsjog “| “v7

‘ZMG (J) wnupiuissia “gq *g

sy

PLATE 7

CAMPBELL

“eIUO}TED

"Iq winyofinpis wnyohsjog

PLATE 8

‘uojkar) “Wsa10.J adrasayy e[JamuURTY yi UI P}22]/0>
*spityy-OMy JNoge paonpar ‘shyoDjsoyjusw)az] jo yuejd umosa-|jn 4°

‘yyey-euo ynoge paonpay
YH (77) 221upjfiez shyopjsoyjunmpary jo yue|d Bunok “VW

CAMPBELL PLATE 9

A. 1, small plant of Danea jenmani Underwood; 2, rhizome of the same species; 3, apex of sterile leaf;
4, fertile leaf; 5, sterile leaf of D. jamaicensis Underwood.
B. 1, young plant of Danea elliptica Sm.; 2, sporophyll of D. jamaicensis; 3, 4, very young
plants of D. jamaicensis (?). :
All Specimens from Jamaica.

CAMPBELL PLATE 10

Adult sporophyte of Danea elliptica. Jamaica.

CAMPBELL

PLATE 11

Kaulfussia zsculifolia Bl.

1, young plant showing the rhizome; 2, sporophyll.
Specimens collected near Buitenzorg, Java.

PLATE 12

CAMPBELL

‘woremef wooly suoutroads Iv
‘UOeZIIWe} Woy Buisue soyAydoiods BunoX “¢ ‘7

‘png snonquaape ue wo1y pedojaaap yueyd 8unof woy jeaq "|

Byeye UneleAy “g

‘y ‘sphq snonquaape YIM aseq-yea] uayey “¢
‘euuid ajniay aj8uis v7 'Z
*Jeo| ene} jo yey *|

‘ZMG Bele eHILTA, “V7

PLATE 13

CAMPBELL

‘ayAydoiods iejiuis B Wlody Jeo] a]suig *¢

“Wnty eyjoid ayy wo1y Buisue ayAydosods Zuno X “b
‘uojhar ‘eXuapesa Wo1y suawioads ‘¢ ‘p ‘erjeaysnyy wWoly suauitoads ‘¢-|

yea] uMoi3-[nj jo ajoned jo woysas-ssold) “¢ |[Aydosods ejo ued ‘7
"WYOPY (Is10.4) DJ2a09 suajdoisupy

‘yuejd jjews e jo xepned

I

INDEX

Adder-tongue fern. See Ophioglossum.
Adventitious buds. See Buds.
Alternation of generations, 209
Aneura, 120
Angiopteris, 4, 117, 118, 120, 121, 126, 139, 140,
WAT DAG eT COM mS 2 1530054, 155,
158, 164, 196, 198, 199, 201, 202,
203, 204, 205, 207
Figs. 88, 89, 95, IOI, 109, 110, III, 112,
124, 130, 134, 180, 181, 182, 183, 187
Plate 13
Angiopteris, species of, 196
Angiopteris evecta (Forst.) Hoffm., 119
Angiopteris pruinosa var. hypoleuca, 122
Annulus of sporangium, 208
Antheridium:
Angiopteris, 126
Anthoceros, 42, 122, 211
Botrychium, 18, 24, 25
Danza, 126, 128
Equisetum, 24
Helminthostachys, 20, 21
Kaulfussia, 127
Lycopodium, 24
Marattia, 126, 128
Marattiacex, 24, 129
Ophioglossum, 22, 23, 24
Anthoceros, Anthocerotes, 42, 122, 210, 211
Apical growth. See Leaf, Root, Stem.
Apogamy (in Botrychium), 52
Archangiopteris henryi, 4, 117, 203, 204
Fig. 184
Archegonium:
Angiopteris, 131
Botrychium, 30, 31
Danza, 132, 133, 134
Helminthostachys, 20, 21
Kaulfussia, 13
Marattia, 126
Ophioglossum, 28, 29
Archesporium:
Botrychium, 115
Helminthostachys, 115
Marattiacez, 206
Ophioglossum, 115
Asplenium nidus L., 10, 13
Blepharoplast, 26, 128, 129
Botrychium, 3, 5, 16, 17, 18, 19, 25, 27, 28, 30,
31, 32, 39) 46, 47, 48, 49, 50, 52, 66,
82, 83, 99, IOI, 102, 103, 109g, IIO,
136, 142, 213
Classification of, 99
Botrychium lanuginosum Wall., 99, 101, 103
Fig. 74

Botrychium lunaria (L.) Sw., 6, 16, 17, 28, 34, 46,

48, 50, 52, 65, 83, 99, 111
Figs. 8, 36, 71
Plate 6

B. matricariefolium A. Br., 16
B. obliquum Muhl., 16, 34, 39, 53, 54, 103, 136,
142
Plate 6
B. silaifolium Pr., 99
Plate 7
B. simplex Hitchcock, 5, 6, 16, 83, 99, 100, 109,
115
Fig. 71
B. ternatum (Thbg.) Sw., 100, 103
Fig. 71
B. virginianum (L.) Sw., 6, 16, 17, 18, 27, 28, 32,
34, 46, 47, 50, 52, 53, 54, 59, 60,
61, 63, 67, 69, 83, 99, 100, IOI, 103,
IIO, I12, 114
Figs, 7, 14; 15, 17, 28, 29, 32, 33, 40,
41, 42, 43, 445 71, 72, 74, 76, 77, 85
Plate 6
Botryopteridex, 3, 214
Bryophytes (see also Mosses, Liverworts), 212
Buds:
in Botrychium, tor
on leaf of Danza sintensis, 178
on gametophyte of Marattiacee, 121
on gametophyte of Ophioglossum, 14
on primary root of Ophioglossum, 40
root buds in Ophioglossum vulgatum, 58, 59
Calcium pectate in Marattiacee, 204
Calcium oxalate crystals in Marattiacee, 204
Cambium, 65, 82
Canal, so-called “canal”? in Helminthostachys,
74, 79
Cauline fibro-vascular bundles (see also Commis-
sural strand), 174, 175, 184, 191,

197
Cheiroglossa (see also Ophioglossum palmatum),
5, 88
Fig. 70
Plate 5
Chlorophyll in gametophyte of Ophioglossum, 9,
12

Christensenia = Kaulfussia, 122
Collateral bundles, Primitive nature of, 214
Collenchyma in:
Angiopteris, 202
Kaulfussia, 186
Marattia, 194
Commissural vascular bundles in—
Angiopteris, 197
Danza, 174, 175

nN
nN
on

226
Commissural vascular bundles in—
Marattia, 191
Kaulfussia, 184
Commissure (of stipules), 187
Completoria complens, 22
Corallorhiza, 33
Coryledon of —
Angiopteris, 146, 147, 151
Botrychium, 50, 51, 52, 64, 67, 83
Danawa, 148, 150
Helminthostachys, 54, 69
Kaulfussia, 147, 149
Marattia, 138, 147, 150, 151
Ophioglossum, 35, 42
Crystals. See Calcium oxalate.
Cycads, 30
Danzxa, 47, 53, 82, 84, 117, 118, 124, 125, 126,

128, 135, 142, 151, 154, 160, 163, |

164, 205, 212
Dana elliptica Smith, 124, 125, 126, 132, 136,
142, 148, 154
Figs. 92, 93, 103, 105, 117, 125, 131, 143,
147, I51, 152, 161. Plates 9, 10
D. jamaicensis Underwood, 124, 126, 136, 142,
144, 146, 148, 154, 155, 156
Figs. 91, 93, 98, 99, 100, 104, 114, 115,
116, 118, 119, 120, 121, 125, 129,
138, 140, 143, 144, 145, 146, 148,
149, 150, 153, 160, 161, 189
Plate 9
D. jenmani Underwood, 124
Figs. 91, 154, 155, 156, 157, 162
Plate 9
D. simplicifolia Rudge, 124, 127, 136, 142, 154,
160, 175, 176, 206
D. sintensis, 178
D. trichomanoides Spruce, 178
Dehiscence of —
Antheridium, 24, 25, 129
Sporangium, 109
Synangium of Marattiacee, 207
Dichotomy of —
Prothallium in Marattiacea, 121
Root in Ophioglossum, 93
Dicotyledons, 65
Dictyostele in —
Angiopteris, 197
Danza, 175
Kaulfussia, 185
Marattia, 192
Drosera, 32
Embryo of —
Angiopteris, 139
Botrychium, 46, 47, 48, 51, 136
Danza, 118, 136, 142
Helminthostachys, 54, 67
Kaulfussia, 141
Marattia, 135, 136, 137
Marattiaceaw, 118, 135
Ophioglossum, 34, 35, 36, 37, 38) 43

INDEX

Endodermis:
Angiopteris, 164, 201
Dania, 163, 167
Helminthostachys, 72
Kaulfussia, 164, 182, 183
Marattia, 164, 193
Ophioglossum, 92
Endarch bundles in Helminthostachys, 77
Endophyte. See Mycorrhiza.
Entomophthorea, 22
Equisetum, Equisetinew, 26, 27, 39, 132, 139
Eubotrychium (see also Botrychium), 100
Euophioglossum (see also Ophioglossum), 83,
86, 89, 91, 93
Eusporangiata, 3
Comparison with Bryophytes, 209, 210, 212
Nature of vascular system, 214
Relation to Leptosporangiata, 217
Fegatella, 33
Ferns, origin of, 209
Fertilization:
Botrychium, 32
Marattiacea, 134
Ophioglossum, 31
Fibro-vascular system (see also Leaf-trace, Stele):
Angiopteris, 196, 198, 199, 201
Botrychium, 60, 62, 66
Danza, 160, 162, 163, 164, 166, 172, 174,
176
Helminthostachys, 73, 76, 77, 78, 106
Kaulfussia, 181, 182, 184, 185
Marattia, 189, 191, 193
Fossils:
Bryophytes, 209
Ferns, 3
Marattiacex, 117
Gametophyte:
Angiopteris, 121
Botrychium, 16, 17, 18
Danza, 124, 125
Helminthostachys, 20, 21, 22
Kaulfussia, 122, 123
Marattia, 119, 121, 122, 210
Ophioglossum, 6, 10, 11, 12, 13, 14, 15, 211
Germination of spores:
Marattiacezx, 119, 120
Ophioglossacez, 7, 8, 9
Gleichenta, mycorrhiza in, 33
Gymnogramme, 26
Hairs:
Marattiacex, 150
Ophioglossum palmatum, 99
Helminthostachys, 5, 8, 10, 19, 20, 21, 25, 31, 32,
54, 67, 68, 69, 70, 71, 725 73s 745 75s
76, 77, 78, 79, 80, 81, 82, 84, 104,
105, 106, 107, 108, 112, 115, 116,
213, 214
Figs. 10, 11, 45, 46, 47, 48 49, 50, 51, 525
53, 54s 78, 79, 80, 86
Plate 8

pore eo

INDEX D227.

Horned liverworts (see also Anthocerotes), 209
Indusium, 204
Isoetes, 205, 206
Kaulfussia, 4, 82, 84, 117, 118, 119, 122, 123, 132,
I41, 147, 149, 152, 153, 154, 155,
157, 158, 164, 178, 179, 180, 181,
182, 183, 185, 186, 187, 206, 208
Hiss00,890; 102) 003, 123, 128, 136,
I4I, 163, 164, 166, 167, 168, 170,
171, 188
Plate 11
Lacune:
Internodal in Helminthostachys, 75
Internodal in Kaulfussia, 184
Leaf:
Angiopteris, 201
Botrychium, 61, 101
Danza, 176, 178
Helminthostachys, 67, 70, 74
Kaulfussia, 185
Marattia, 194
Marattiacez, 118, 157, 159, 214
Ophioglossum, 57, 84, 87, 88
Leaf, anatomy:
Angiopteris, 202
Botrychium, 102
Danza, 160
Helminthostachys, 107
Kaulfussia, 187
Marattia, 194, 195
Ophioglossum, 93, 96
Leaf, fertile (see also Sporophyll), 5, 85, 109, 204,
213
Leaf, gaps, 78, 173
Leaf, trace, 66, 72, 80, 173, 186, 191, 197
Leptosporangiata, 3, 217
Liverworts, mycorrhiza in, 33
Lycopodium, 9, 10, 24
L. cernuum, 9, 10
Mantle cells (of antheridium), 24, 129
Marattia, 117, 119, 120, 122, 126, 128, 132, 135,
136, 137, 147, 149, 152, 153, 155,
156, 164, 188, 189, 192, 193, 194,
195, 204, 206
M. alata Swartz, 138, 188, 191, 192, 193, 194
Figs. 175, 176,177. Plate 12
. cicutzfolia KIf., 119, 132, 136
. douglasii (Pr.) Baker, 119, 120, 122, 126, 135,
136, 137, 147, 149, I51, 153, 156,
188, 189, 190, 205, 210
Figs. 87, 88, 94, 106, 107, 108, 122, 127,
132, 133, 141, 172, 173; 174, 177,
185, 190, I91
M. fraxinea Smith, 120, 188, 191, 193
Figs, 87, 186
M. salicifolia Schrad., 193
M. sambucina Blume, 120, 188
Fig. 87
M. weinmannizfolia Liebm., 136

<a

Marattiacez, 3, 35, 39, 48, 53, 61, 83, 84, 117,
129; 130, 134, 135, 209, 212, 214,
215

Macroglossum, 117, 204

M. alide Copeland, 204

Mesarch vascular bundles in Helminthostachys,
78

Monotropa, 33

Mosses, 209

Mucilage cells, 168, 170, 173, 177, 182, 185, 187,
190

Mucilage ducts, 168, 170, 173, 177, 182, 185, 187,
190

Mycorrhiza, 6, 9, 11, 15, 18, 19, 20, 21, 22, 32,
335 L275 079, Lome 2k

Operculum (of antheridium), 24, 25, 128, 129

Ophioderma (see also Ophioglossum), 5, 87, 94

Ophioglossacez, 3, 5, 6, 7, 34, 82, 86, 108, 109,
208, 213, 214

Ophioglossum, 5, 6, 7, 9, 10, II, 12, 13, 14, 15,
22, 24, 26, 27, 28, 35, 39; 42, 43, 56,
60, 82, 83, 85, 86, 87, 89, 91, 207,
209, 210, 213, 214, 215

O. bergianum Schlecht, 5, 87, 92

O. capense Sw., 92

O. californicum Prantl., 5

O. ellipticum Hk., 92

O. intermedium Hooker, 88, 97,

Fig. 69
Plate 4
O. lusitanicum L., 86, 87
O. moluccanum Schlecht., 5, 6, 7, 11, 12, 26, 28,
34, 35, 36, 38, 39, 40, 42, 45, 55,
56, 57, 59, 86, 90, 94, 112, 210, 212
Bigs: 25 4, U2) 08.223) An oc 26. 275
37, 38, 39, 55, 56, 57, 58, 59, 60, 61,
62, 81, 83, 192
Plates 1, 3
O. palmatum L., 88, 89, 98, 99
Vig. 70
Plate 5
O. pedunculosum Desy., 10, 11, 13, 34, 36, 39, 40,
42, 57
Fig. 3
O. pendulum L., 5, 6, 7, 9, 10, 14, 18, 26, 28, 29,
36, 37, 38, 40, 42, 44, 56, 88, 95, 96,
109, I12
Figs. 1, 3, 4, 13, 16, 20, 21, 63, 64, 65, 66,
67, 68, 82, 84
Plates 1, 2, 4
O. reticulatum L., 6, 40, 90
O. simplex Ridley, 88, 98, 109
Fig. 71
O. vulgatum L., 3, 5, 6, 10, 13, 15, 27, 28, 29, 34,
43, 44, 57s 58, 59, 86, 87, 92
Figs. 3, 5, 19
Orchids as humus saprophytes, 33
Osmunda, Osmundacezx, 121, 123, 207
Osmundopteris. See Botrychium virginianum.
Palisade tissue, 107, 178, 195, 202

228

Pellia, 122
Periderm, 66, 80, 193
Peronosporex, 22
Phyllotrichium (see also Botrychium), 100, 102
Pith, in Helminthostachys, 76, 79
Polypodium quercifolium, 10
Prothallium. See Gametophyte.
Pro-ophioglossum, 211
Protocorm, 53
Protophloem in Angiopteris, 201
Protostele, 175, 188
Protoxylem:
Angiopteris, 201
Helminthostachys, 79, 82
Kaulfussia, 185
Pteris cretica, 53
Pythium, 22
Rhizoids:
Botrychium, 18
Danza, 127
Helminthostachys, 20
Kaulfussia, 123
Ophioglossum, 12
Rhizome (see also Stem):
Botrychium, 101
Danza, 175, 176, 177
Helminthostachys, 106
Kaulfussia, 186
Ophioglossum, 91, 94
Root:
Angiopteris, 140, 202, 203
Botrychium, 47, 51, 64, 103, 104
Danza, 157, 164, 177, 179
Helminthostachys, 70, 80, 81, 105, 107, 108
Kaulfussia, 187
Marattia, 138, 156, 192, 195
Ophioglossum, 35, 39, 43, 56, 83, 87, 89, 93,
97, 98

Root apex:
Botrychium, 49
Danza, 178
Helminthostachys, 72, 80
Marattia, 138, 156, 195
Ophioglossum, 94
Root hairs, multicellular, of Kaulfussia, 183, 187
Scales, epidermal:
Danza, 151
Helminthostachys, 74, 75
Kaulfussia, 180
Marattiacex, 150
Sceptridium. See Botrychium obliquum.
Sclerenchyma, 170, 171, 194
Secondary wood:
Angiopteris, 204
Botrychium, 65, 82 |
Helminthostachys, 78
Sex-organs. See Antheridium, Archegonium.
Sieve tubes, 151, 163, 201, 202
Siliceous deposits in Marattiacex, 204 |

INDEX

Siphonostele:
Angiopteris, 197
Kaulfussia, 184
Marattia, 188

| Spermatogenesis:

Botrychium, 28
Marattiacea, 129, 130
Ophioglossum, 26, 27
Spermatozoids:
Botrychium, 28
Marattiacew, 130
Ophioglossum, 26, 27
Spike of Ophioglossacew. See Sporangiophore.
Sporangium (see also Synangium):
Angiopteris, 205
Botrychium, 109, 111, 114, 115
Danza, 205, 206, 207
Helminthostachys, 111, 116
Kaulfussia, 207
Marattia, 205
Ophioglossum, 109, 111, 113
Sporangiophore:
Botrychium, 109, 110
Helminthostachys, 105, 106
Ophioglossaceaw, 5, 85, 108, 109, 208
Ophioglossum, 109, 110
Spore:
Marattiacex, 208
Ophioglossacex, 6, 7
Spore division, 114
Sporophyll:
Angiopteris, 204, 206
Archangiopteris, 204
Botrychium, 100, 102
Danza, 204
Helminthostachys, 111, 116
Kaulfussia, 204, 208
Marattia, 204
Marattiacew, 204, 208, 214
Ophioglossum, 85, 88, 93, 109, 110, 112, 214
Sporophyte (see also Embryo):
Angiopteris, 196, 198, 199, 201
Botrychium, 51, 59, 60, 62, 63, 99
Danza, 163, 178
Helminthostachys, 54, 67, 68, 77, 104, 105
Kaulfussia, 179, 180, 186
Marattia, 188, 189
Ophioglossaceaw, comparison of young spor-
ophyte, 82
Ophioglossum, 38, 39, 445 455 55
Staubgrubchen of Marattiacee, 204
Stele:
Botrychium, 82 :
Helminthostachys, 52, 75, 8
Stem, stem apex:
Angiopteris, 153, 198, 199
Botrychium, 49, 53, TOI, 103
Danza, 118, 136, 156, 170
Helminthostachys, 70, 71, 74
Kaulfussia, 185, 187

INDEX 229

Stem, stem apex: | Synangium, 204, 205, 206, 207, 208
Marattia, 192 | Tannin cells:
Marattiacex, 154, 162 Angiopteris, 146
Ophioglossum, 42, 50, 56, 89, 91, 94, 97, 99 Danewa, 165, 169, 171
Sterilization of sporogenous tissue, 209 Helminthostachys, 79, 84

Stipule, stipular sheath:
Botrychium, 61, 101
Danza, 170
Helminthostachys, 71, 73, 105
Kaulfussia, 185, 187

Kaulfussia, 185

Marattia, 189

Marattiaceze, 150
Tapetum, 111, 116, 206

Marattia, 195 Trabeculz, 207
Marattiacex, 118 Tracheary tissue:
Ophioglossacee, 83, 84 Angiopteris, 201
Ophioglossum, 91 Botrychium, 66

Stomata: ; Helminthostachys, 68, 79, 82
Botrychium, 1o1 Kaulfussia, 185
Danza, 151 Marattia, 189

Helminthostachys, 106
Kaulfussia, 152, 187
Marattia, 195
Ophioglossum, 96
Suspensor: i
Botrychium, 47, 48, 53, 136 | Helminthostachys, 69, 81
Danza, 118, 136 Ophioglossum vulgatum, 35

Ventral canal-cell, 30, 31, 133, 134, 176, 187, 194
201, 213
Vestigial leaves:
Botrychium lunaria, 51

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