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The Cambridge Manuals of Science and
Literature

LINKS WITH THE PAST IN
THE PLANT WORLD

CAMBRIDGE UNIVERSITY PRESS

ilontion: FETTER LANE, E.G.

C. F. CLAY, Manager

(JFliinbiirflJ} : loo, PRINCES STREET

ILcntlon: H. K. LEWIS, 136, GOWER STREET, W.C.

Berlin: A. ASHER AND CO.

1Lap>ig: F. A. BROCK HAUS

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Sequoia magnifica Knowlton, in the Yellowstone National Park.
(From a photograph kindly supplied by Prof. Knowlton.) See p. 104.

CambriHgc :

PRINTED BY JOHN CLAY, M.A.
AT THE UNIVERSITY PRESS

3^

^7

With the exception of the coat of arms at
the foot^ the design on the title page is a
reproduction of one used by the earliest knonvn
Cambridge printer, John Siberch, 1 5 2 1

PREFACE

1\ /TY object in writing this book is primarily to
call attention to some of the many questions
which are raised by an enquiry into the relative
antiquity of existing plants,- and to illustrate the
nature of the evidence afforded by the records of
the rocks. One may agree with the dictum, * There
is but one art — to omit/ but to practise this art is
often a difficult task. While fully conscious of the
incompleteness of the treatment of the subjects dealt
with in these pages, and of defects in the method of
presentation, I hope that I may succeed in attracting
some of my readers who are already interested in
living plants to the study of plants of former ages.

I am greatly indebted to my colleague Dr C. E.
Moss for reading the proofs and for many valuable

viii PREFACE

suggestions. I wish to thank Mr and Mrs Clement
Reid, Prof. MacDougal of the Arizona Desert Labo-
ratory, Prof Campbell of Stanford Universit}, Prof
F. H. Knowlton of the United States National
Museum, Washington, Mr A. G. Tansley, Prof Yapp,
and Mr W. R. Welch for photographs which they
have allowed me to reproduce. As on many previous
occasions, I am indebted to my wife for contributing
drawings.

A. C. SEWARD.

Botany School, Cambridge.
July 1911.

The niiinbers in brackets interspersed in the text refer to the
Bibliography at the end of the volume.

CONTENTS

PAGE

Preface

vii

CHAP.

I.

Introductory : the Longevity of Trees, etc.

1

11.

The Geographical Distribution of Plants .

15

III.

The Geological Record

39

IV.

Preservation of Plants as Fossils

56

V.

Ferns ; their Distribution and Antiquity .

71

VI.

The Redwood and Mammoth Trees of California

95

VII.

The Araucaria family

106

VIII.

The Maiden Hair Tree

121

Bibliography

134

Index

139

Links loith the Past

ERRATUM
Page 78. Omit lines 5, 6, and 7, from "One" to *'but" inclusive.

CHAPTER I

INTRODUCTORY: THE LONGEVITY OF TREES, ETC.

' Believe me who have tried. Thou wilt find something more in
woods than in books. Trees and rocks will teach what thou canst
not hear from a master.' St Bernard.

The recent publication in the daily press of
instances of human longevity under the heading
^ Links with the Past' prompted a comparison between
the length of time represented by the duration of a
tree and the lifetime of a human being. The com-
parison of single lives suggested the further step of
contrasting the antiquity of the oldest family-histories
with the remoteness of the period to which it is
possible to trace the ancestry of existing members of
the plant kingdom.

My primary object in these pages is not to deal with
familiar cases of longevity in trees, but to consider
in the first place some of the problems connected with
the origin of the present British flora, and then to
describe a few examples of diflerent types of plants

s. 1

2 LINKS WITH THE PAST [CH.

whose ancestors flourished during periods of the
earth's history long ages before the advent of the
human race.

In dealing with plants of former ages we are
confronted with the difficulty of forming an adequate
conception of the length of time embraced by geo-
logical periods in comparison with the duration of
the historic era. Some of the ' Selections from the
Greek Papyri' recently edited by Dr Milligan
(Cambridge 1910) refer to common-place events in
terms familiar to us in modern letters : we forget
the interval of 2000 years which has elapsed since
they were written. Similarly, the close agreement
between existing plants and species which lived in
remote epochs speaks of continuity through the ages,
and bridges across an extent of time too great to
be expressed by ordinary standards of measurement.
Terms of years when extended beyond the limits
to which our minds are accustomed cease to have
any definite meaning. While there is a certain
academic interest in discussions as to the age
of the earth as expressed in years, we are utterly
unable to realise the significance of the chronology
employed. After speaking of the futility of attempting
to introduce chronological precision into periods so
recent as those which come into the purview of
archaeologists, Mr Rice Holmes suggests a method
better adapted to our powers. He says — * Ascend

I] INTRODUCTORY 3

the hill on which stands Dover Castle, and gaze
upon Cape Grisnez, let the waters beneath you
disappear ; across the chalk that once spanned the
channel like a bridge men walked from the white
cliff that marks the horizon to where you stand.
No arithmetical chronology can spur the imagination
to flights like thesed).' On the other hand, the
use in some country districts in Britain of spindles
almost identical with instruments used in spinning
by the ancient Egyptians, and similar survivals
described by the author of a book entitled The
Past in the Present(2), bring- within the range
of our vision an early phase of the historic era.
The rude implements still fashioned by the flint-
knappers of Brandon in Suffolk connect the present
with the Palaeolithic age. Measured from the
standpoint of historic reckoning, survivals from
prehistoric days appeal to us as persistent types
which have remained unchanged in a constantly
changing world.

In one of his essays Weismann quotes an old
German saying with regard to comparative longevity,
which asserts that *a wren lives three years, a dog
three times as long as a wren ' and so on in a regu-
larly ascending series : the life of a deer is estimated
at three times that of a crow and an oak three times
that of a deer, which means that, computed on this
basis, an oak lives nearly 20,000 years (3) ! This

1—2

4 LINKS WITH THE PAST [CH.

fanciful illustration of the relative longevity of an

oak is the exi)ression of a truth, namely the superiority

of trees over animals in regard to the duration of

life. As a seventeenth-century translator of Pliny's

Natural History writes, ' In old times trees were the

very temples of the gods : and according to that

antient manner, the plaine and simple peasants of

the country, savouring still of antiquity, do at this

day consecrate to one God or other, the goodliest

and fairest trees that they can meet withal.' Oaks

growing in Pliny's day in the Hercynian forest are

said to have been there 'ever since the creation of

the world (4).' Sir Joseph Hooker, in an account

of some Palestine oaks, gives a drawing of a famous

tree at ^lamre, known as Abraham's Oak, which is

supposed to mark the spot where the Patriarch

pitched his tent (5). Examples such as these,

though of no scientific value, serve to illustrate the

well-founded -belief in the extraordinary longevity of

trees. In the absence of evidence to the contrary, it

would be rash to deny the possibility that \yilliam

the Conqueror's Oak in Windsor Forest, described

by Loudon in his Arhoi'etmn Brltannicimi and

mentioned by later writers, may be a survival from

the reign of the king whose name it bears. Although

it is seldom possible to state with confidence the

exact age of old oaks and yews famed for length of

days, there can be no doubt as to the enormous

I] INTRODUCTORY 5

antiquity of many of our trees whose years are
^sacred with many a mystery.' The section of a
trunk of one of the mammoth trees of California
(Sequoia gigantea) exhibited in the Natural History
department of the British Museum, shows on its
polished surface 1335 concentric rings denoting
successive increments of wood produced by the
activity of a cylinder of cells situated between the
hard woody tissue and the bark. It is generally
assumed that each year a tree produces a single
ring, though, as is well known, an estimate of age
calculated on this assumption cannot be regarded as
more than an approximation to the truth. If this
giant tree, which was felled in 1890, was then 1335
years old, it had already reached an age of over two
centuries when Charlemagne was crowned Emperor
at Rome. The concentric rings on a tree trunk owe
their existence to certain structural differences be-
tween the wood formed in the spring and in the late
summer. In Sequoia, as in other members of the
great class of cone-bearing trees, the wood is com-
posed of comparatively narrow elements which serve
to carry water from the roots to the branches and
leaves. As spring succeeds winter the inactivity
of the plant-machine is followed by a period of
energetic life ; opening buds and elongating shoots
create a demand for a plentiful supply of ascending-
sap, and in response to this the tree produces a fresh

6 LINKS WITH THE PAST [CH.

cylinder of wood composed of relatively wide con-
ducting tubes. After the first rush of life is succeeded
by a phase of more uniform and gentler activity, the
demand for water becomes less exacting and the
wood which is formed during the rest of the growing
season consists of narrower water-pipes. A period of
rest ensues, until in the following spring new layers
of larger tubes are laid down in juxtaposition to the
narrower elements of the latest phase of the preceding
summer. This alternation of larger and smaller
tubes produces the appearance of concentric rings on
a cross-section of a tree. It is not the pause in the
active life of the plant which is responsible for the
effect of rings, but the fact that the wood produced
immediately before and immediately after the pause
is not structurally identical. In trees grown under
the more uniform conditions of certain tropical
regions, the annual rings are either feebly developed or
absent ; for example, in some Indian oaks the wood
shows no concentric rings of growth.

Stated in general terms, rings of growth in the
wood of a tree are the expression of a power possessed
by the plant of regulating the structure of its com-
ponent elements in response to the varying nature of
the external stimuli. In certain circumstances, for
example after the destruction of the young buds by
caterpillars, the tree makes a special effort to repair
the loss by producing a new set of shoots. This may

I] INTRODUCTORY 7

be recorded by the occurrence of two concentric rings
in one season. An extreme instance of departure
from the normal has recently been described (6) in
which a tree of Tkeobroma cacao (the cocoa tree),
planted in Ceylon in the summer of 1893 and felled
in January 1901, after a life of just over 7 years, was
found to have 22 rings in its stem. In this case the
tree shed its leaves three times a year, and each break
in the uniformity of its vital activities was registered
by the apposition of Avhat under ordinary conditions
are spoken of as spring and late-summer wood.
At Aden trees stated by natives to be very old
showed only five or six rings of wood, a fact connected
with the almost complete lack of rain and with the
uniform conditions of existence.

The degree of accuracy to be allowed to estimates
of age founded on the number of 'annual' rings is,
however, of secondary importance in comparison
with the enormously greater hold on life possessed
by trees as contrasted with the higher animals. Early
in the nineteenth century the Swiss botanist A. P.
de Candolle expressed the opinion that trees do not
die from senile decay, but only as the result of injury
or disease. Trees are constructed on a plan funda-
mentally diflferent from that underlying the structure
of the highly complex human organism, and are thus
endowed with a sort of potential immortality. It has
been suggested that some of the large corals in the

8 LINKS WITH THE PAST [CH.

Red Sea which are still tenanted by living polyps
may have been growing in the days of the Pharaohs.
The coral polyp represents the growing portion of a
lifeless mass of rock which is constantly extended by
the activity of the organism at the summit of each
branch. Between a coral-reef and a tree there are
many essential differences, but a rough analogy may
be recognised. A tree, unlike the higher animals,
does not reach a stage at which the whole of its
substance attains a condition of permanence and
fixity. It consists of a complex branching-system
in which each shoot increases in length by virtue
of the youthful vigour of its apex : to a large extent
the tree as a whole consists of lifeless material in-
capable of further growth, as is the case of the older
portions of a coral-reef ; but the regular increase in
girth of the trunk and its branches demonstrates that
this comparison is only partially true, and that the
power of growth in a tree is not confined to the
extremities of the youngest shoots. The tip of every
twig is composed of minute cells endowed with a
potentiality of development like that which charac-
terises the embryonic tissues of a seedling just
emerged from the seed. In the course of its growth,
each branch, by means of its living and dividing-
cells, contributes to the several parts of the complex
mechanism of the tree. While the greater number
of cells acquire a permanent form and lose the

i] INTRODUCTORY 9

power of further development, there remains a cy-
linder of cells endowed with perpetual youth. This
cylinder of living cells, known as the cambium, extends
between the wood and bark from one end of the tree
to the other : by its periodic activity it adds new layers
of tissue each year and thus, by increasing the amount
of conducting tubes for the transport of water and
for the distribution of elaborated food, it enables the
tree to respond to the increasing demands which
are the necessary accompaniment of increasing size.
It has already been pointed out that in the spring
when the sap flows most vigorously the cambial
cylinder produces larger tubes, and afterwards when
the tree settles down to its normal life, these are
succeeded by narrower and stronger tubes. These
later formed elements serve also an important me-
chanical purpose ; by the strength of their walls they
increase the supporting power of the tree and enable
it to sustain the added burden of the annual increase
in the weight and extent of its spreading branches.
It is the persistence of permanently juvenile tissue
in certain regions of a tree, together with the re-
markable power of repairing injuries and shedding
effete parts, that constitute some of the most striking
contrasts between the higher animals and plants.
The embryo oak in the earlier stages of development
consists entirely of actively growing cells ; by degrees
differentiation of the embryonic tissues results in the

10 LINKS WITH THE PAST [ch.

localisation of regions of cell-prodnction at the tips
of the elongating stem and root. These apical groups
of cells are, in fact, portions of the embryonic organism
Avhich persist so long as the plant lives. This con-
tinuity between the growing tip of an old oak stem
and the cells of the undifferentiated embryo affords
one of the most remarkable examples in nature of
a link between the past and the present.

If we pass beyond the stretch of time represented
by the life of a single tree, a few successive genera-
tions suffice to carry our retrospect back to the days
when forests of oaks, birches, and other trees im-
peded the progress of the Roman invaders, and, a
stage farther back, to the age of Neolithic man whose
remains are occasionally found in our heaths and
moors and in the submerged forests round our coast.
The blocks of oak and beech, some of Avhich are as
sound as when first felled, recently discovered below
the foundations of parts of Winchester Cathedral con-
structed at the end of the twelfth or in the opening
years of the thirteenth century, are relics of Xorman
forests. In the course of some excavations at Brigg in
Lincolnshire in 188G a dug-out boat was found nearly
50 feet long and from 4 to 5 feet in breadth. The stem
of the oak from which the canoe had been fashioned
shows no sign of branching for a length of over 40
feet, a fact which points to the growth of the tree
in a forest where the race for liaht induced the

I] INTRODUCTORY 11

development of clean columnar stems. The Brigg
'dug-out,' now in the Hull Museum, Avas discovered in
an old alluvial valley of the Ancholme river, formerly
connected with the Humber, and it may be that
it was used by Neolithic man as a ferry for river-
service (7).

From the period claimed by archaeologists we
pass by gradual stages into the domain of the
geologist. As Huxley wrote, 'when even the dim
light of Archaeology fades, there yet remains Palae-
ontology, which... has brought to daylight once more
the exuvia of ancient populations, whose world was
not our world, who have been buried in river beds
immemorially dry, or carried by the rush of waters
into caves, inaccessible to inundation since the dawn
of tradition (8).' The length of time represented by
a succession of long-lived individuals of the same
species becomes enormously extended when we pass
to the history of families, and disinter from the
sediments of other ages the remains of extinct types.
As we descend the geological series familiar types
gradually disappear, and through a succession of
changing floras we penetrate to the fragmentary
records contained in the older rocks until the absence
of documents sets a limit to our quest.

The Scots pine shares with the oak, the beech,
the aspen, the yew, and several other trees the right
to be included in the native flora of Britain. In the

12

LINKS WITH THE PAST

[CH.

peat-beds of Scotland even up to 3000 feet above
sea-level the stumps of pines occur in abundance,
and in many places recent researches have revealed
the occurrence of successive forests of pines, oaks,
and spruces separated from one another by the

Fig. 1. Piniis sylvestris Linn, in the Black Wood of Rannoch.
(Photograph by Mr A. G. Tansley.)

accumulations of swampy vegetation O). The spruce
fir has long- ceased to be a member of the British
flora, but in a few localities in the Scottish High-
lands patches of primeval pine forests remain. The

I] INTRODUCTORY 13

accompanying photograph (Fig. 1), taken by my friend
Mr A. G. Tansley, in the Black Wood of Rannoch in
north-west Perthshire, shows a few trees of Plnus
si/lvestris growing in their native soil : the form of
the older tree {A) suggests comparison with that of
a well-grown beech such as we are familiar with
in English plantations. This spreading dome-shaped
habit seems to be a peculiarity of the Highland tree,
and is one of the characters which have led some
botanists to regard it as a variety (Pinns sylvestris
var. scotica) of the ordinary Scots pine. Though it
is doubtful if any relics of primeval pine woods are
left in England, abundant evidence of the former
existence of the Scots pine is afforded by the sub-
merged forests exposed at low-tide on many parts of
the English and Welsh coasts and at the base of
some of the English peat moors. During the con-
struction of the Barry docks on the north coast of
the Bristol Channel a few years ago, the exposed
sections of peat and forest beds were investigated by
Dr Strahan and by Mr Clement Reid. There is
evidence of a subsidence of the land to an extent of
55 feet since the formation of the lower peat-beds
containing oak, hazel, willow, and other trees. The
pine, unknown in Wales during the historic period,
was recognised in the Barry cutting. The occurrence
of a polished flint implement assigns a date to the
uppermost portion of this old land-surface do).

14 LINKS WITH THE PAST [ch. i

It is impossible within the limits of a small volume
to discuss in detail the evidence furnished by the
records of the rocks as to the relative anti(iuity of
the different constituents of the present vegetation
of Britain. In later chapters a few selected plants
are described which are pre-eminently ancient types.
Before passing to the consideration of the data on
which the geological history of plants is based, brief
reference may be made to one of the most interesting
and difficult problems of botanical research, namely
the history of the British flora.

CHAPTER II

THE GEOGRAPHICAL DISTRIBUTION OF PLANTS

* No siaeculation is idle or fruitless that is not opposed to truth
or to probability, and which, whilst it co-ordinates a body of well
established facts, does so without violence to nature, and with a due
regard to the possible results of future discoveries.'

Sir Joseph Hooker.

In the vegetation of the British Isles the leading
role is played by that large group to which the term
Flowering Plants is frequently applied. This group,
including the two sub-divisions Dicotyledons and
Monocotyledons, is known by the name xAngiosperms,
a designation denoting the important fact that the
seeds are developed in an ovary or protective seed-
case (dyyelov, a vessel or box). The fact that these
highly elaborated products of development made
their appearance, so far as we know, at a compara-
tively late stage in the history of the plant-world,
att'ests their efficiency as a class and demonstrates
the rapidity with which they have overspread the
surface of the earth as successful competitors in

16 LINKS WITH THE PAST [ch.

the struggle for existence. As Darwin wrote in a
letter to Sir Joseph Hooker in 1881, 'Nothing is
more extraordinary in the history of the vegetable
kingdom, as it seems to me, than the apparently
very sudden or abrupt development of the higher
plants(ii).' In another letter (1879) to the same friend
we read, 'The rapid development as far as we can
judge of all the higher plants within recent geological
times is an abominable mystery (12).' Making allow-
ance for the probability, or indeed certainty, that
the imperfection of the geological record tends to
exaggerate the apparent suddenness of the ap-
pearance of this vigorous class, and allowing for
the fact that our knowledge of the records of
the rocks in which the highest plants first occur
is very incomplete, we cannot escape from the
conclusion that this recently evolved group spread
with amazing rapidity. Various reasons may be
suggested in explanation of the dominant position
Avhich the Angiosperms hold in the floras of the
world. As an instance of their rapid increase during
the Cretaceous epoch ^, the period which has furnished
the earliest satisfactory records of Flowering Plants,
the following statement by an American writer may
be quoted : — ' The rapidity with which it [/.e. the
group of Flowering Plants] advanced, conquering or

1 For the position of the Cretaceous and other systems in the
geological series, see the table on page 42.

n] GEOGRAPHICAL DISTRIBUTION 17

supplanting all rivals, may be better understood
when we remember that it forms 85 7o ^f the flora
of the Dakota group ' ; that is a series of sedimentary
rocks in Dakota referred by geologists to the middle
of the Cretaceous period (is). In the Wealden rocks
of England, which are rich in the remains of Lower
Cretaceous plants, no undoubted Flowering Plant
has so far been found.

The more efficient protection of the ovules, the
germs which, after fertilisation, become the seeds,
the extraordinary variety in the floral mechanisms
for assisting cross-pollination, the arrangements for
nursing the embryo, and the structural features of
the wood in relation both to rapid transport of water
and to the storage of food, are factors which have
pi'obably contributed to the success of the Angio-
sperms. The degree of weight to assign to each
contributing cause cannot as yet be satisfactorily
determined, but the general question raised by the
recent origin of these latest products of evolution
offers a promising field for work. While admitting
our inability at present to do more than suggest
possibilities, we may encourage research by specula-
tion.

The members of the Vegetable Kingdom placed
next to the Flowering Plants are the Gymnos perms
or naked-seeded {yv/iv6<;, naked) plants, including
(i) the Conifers, e.g. pines, firs, larches, the yew, etc.,

s. 2

18 LINKS WITH THE PAST [CH.

(ii) a small group of plants known as the Cycads,
whose existing members, now almost confined to
a few tropical regions, are the descendants of a
vigorous race represented by many species in the
floras of the Mesozoic epoch. A third sub-division
of the Gymnosperms, the Ginkgoales, is represented
by a single survivor, which is described in a later
chapter as one of the most remarkable links with the
past in the plant kingdom.

The Gymnosperms are geologically very much
older than the Angiosperms. Members of this class
played a prominent part in the vegetation of the
Coal age and it is certain that they existed in the
still older Devonian period. The only other group
to which reference is made in later chapters is that
of the Ferns, one of the sub-divisions of a large class
known as the Vascular Cryptogams or Pteridophyta.
These plants, like the Gymnosperms, are represented
in the oldest floras of which recognisable remains
have been preserved. The main groups of the
vegetable kingdom, founded on existing plants, are
distinguished by well-defined differences ; they are
comparable with separate twigs of a tree springing
from larger branches and these again uniting below
in a common trunk. The vegetation of to-day re-
presents only the terminal portions of the upper
branches. As we descend the geological series,
records of extinct types are found which enable

II] GEOGRAPHICAL DISTRIBUTION 19

us either to trace the separate branches to a common
origin or to recognise a convergence towards a
common stock. Were a botanist to find himself in
a forest of the Coal age he would experience great
difficulty in assigning some of the plants to their
s} stematic position : characters now regarded as
distinguishing features of distinct groups would be
met with in combination in a single individual. It
is by the discovery of such generalised types, which
serve as finger-posts pointing the way to lines of
evolution, that the student of pre-existing plants has
been able to throw light on the relative antiquity of
existing forms, and to trace towards a common
ancestry plants which now show but little indication
of consanguinity.

Confining our attention to the dominant group of
plants in the British flora, namely the Flowering
Plants, we may profitably consider the question,
though we cannot satisfactorily answer it, — which
members of this group are entitled to be regarded
as the most ancient inhabitants ? The past history
of our native plants, and their geographical range,
not only in the British Isles but on the Continent
of Europe, are subjects well worthy of the attention
of field-botanists whose interests are apt to be
confined within too narrow bounds. There are
numerous problems relating to the composition of
the present vegetation of Britain which might be

2—2

20 LINKS WITH THE PAST [CH.

discussed in reference to the relative antiquity of
plants ; but in a single chapter it is impossible to do
more than call attention to certain considerations
which are frequently overlooked by students of
British species.

It is customary to speak of the British flora as
consisting for the most part of species introduced
into this country by natural means, while some
plants owe their introduction to human agency or
are 'escapes' from cultivation. It is by no means
an easy task in some instances to decide whether a
species is native or introduced, but in some cases,
a few of which are mentioned, there is no doubt as to
the alien nature of the plants. The term 'native'
needs a word of explanation. It is not intended to
convey the idea that a plant so designated came into
existence on British soil and spread thence to other
regions ; but by native species we mean such as have
reached this country by migration from other lands,
or it may be in some instances have actually origin-
ated in this part of Europe. One of the best known
aliens in Britain is the American water-weed, Elodea
cmiadensis {OY Anacharis alsinastrmn), which was
discovered about sixty years ago in a canal near
Market Harborough in Leicestershire (u). In all pro-
bability this North American species was introduced
into England with timber. Once established, it
spread through the waterways with alarming rapidity

II] GEOGRAPHICAL DISTRIBUTION 21

and became a serious pest. Elodea affords an admir-
able instance of the serious interference with the
balance of Nature by the introduction of a new
competitor into an environment conducive to
vigorous development. Another foreign water-plant,
Naias graminea, for the importation of which
Egyptian cotton may be responsible, has been
recorded from the Reddish canal near Manchesterds).
This African and Asiatic species occurs in Europe only
as a colonist ; it is said to have been introduced into
Italy with East Indian rice. A more recent case of alien
immigration due to unintentional human agency is
that of Potamogeton ^yennsglvanicus, a pond- weed of
Canada, the United States, Jamaica, and elsewhere.
Specimens of this species were first noticed in 1907
in a canal near Halifax close to the effluent from
a cotton mill. Since its discovery the plant has
slightly extended its range. It is suggested by
Mr Bennett, who first identified the alien, that its
fruits were brought to this country in goods from
the United States (le).

Of the introduction of these and other foreign
plants we have satisfactory records ; but there are
many others which may owe their presence to man's
agency, though we have no information as to their
arrival.

It has long been recognised that several members
of the British flora are related to Scandinavian

22 LINKS WITH THE PAST [ch.

species. The Scandinavian flora, as Sir Joseph
Hooker says in his well-known paper on the 'Out-
lines of the Distribution of Arctic plants,' ' not only
girdles the globe in the Arctic Circle, and dominates
over all others in the North Temperate Zone of the
Old World, but intrudes conspicuously into every
other temperate flora, whether in the northern or
southern hemisphere, or on the Alps of tropical
countries '(17). The vicAV generally held is that during
the Glacial period this Arctic flora was driven
South, and aided by land-bridges, which were after-
wards submerged, many of the northern migrants
found a more congenial home in Britain. It is how-
ever by no means improbable that this conclusion
may have to be considerably modified. Mr and Mrs
Reid, as the result of their careful analysis of the
Pre-Glacial Flora of Britain, express the opinion that
Hhe pre-glacial plants suggest climatic conditions
almost identical with those now existing, though
slightly warmer' (27, 2). It is noteworthy that the
list of plants given in their paper does not include
any typical Arctic species. The occurrence on the
mountains of Scotland and elsewhere of such plants as
Silene acaulis, Dry as octopetaJa, Saxlfraga oppositi-
folia and other Saxifrages, Ruhns chamaemorus (the
Cloudberry), and the dwarf Birch illustrate the Arctic-
Alpine element in our flora.

The opinion is held by many Swiss botanists that

II] GEOGRAPHICAL DISTRIBUTION 23

their Alpine species have in large measure been
derived from non-glaciated parts of the Pyrenees, that
is from a region which was presumably able to retain
its flora at a time Avhen more northern lands were
exposed to extreme Arctic conditions. My friend
Dr Moss believes that some of the so-called Scandi-
navian plants came to Britain from Central Europe
after the retreat of the ice ; if this view is correct it
means that some at least of our iVrctic-Alpine plants
reached these islands by a southern rather than by
a northern route.

Interesting examples of far-travelled northern
plants recently described by Professor Engler of
Berlin afford additional illustrations of the general
principles enunciated many years ago by Sir Joseph
Hooker. A species of flowering Rush, Luzula
spicata var. simensis, occurs at an altitude of 3600
metres in Abyssinia and on Kilimanjaro. Luzula
spicata is found in the whole of the Arctic and
Subarctic belt in Scotland, Auvergne, the Jura
mountains, and elsewhere. The species probably
began its career in the northern hemisphere where
it grew abundantly on the higher ground in the
Arctic Circle : it eventually travelled along the
North American Andes and appeared in Mexico
under a guise sufficiently distinct to warrant the
use of another name, Luzula racemosa. In an
eastern direction it reached the Himalayas and is

24 LINKS WITH THE PAST [cu.

]oi)i'osentc(l in Abyssinia by a closely allied form.
P^roni Abyssinia to Kilimanjaro Luzula spicata ' had
to travel a long distance ; but it is not impossible
that it either still exists or has existed previously
on a few of the high mountains between Abyssinia
and Kenia, from which, having advanced to the
Kilimanjaro, it again produced new forms.... At any
rate, it is impossible to do without distribution of
seeds of alpine plants by air-currents or by birds
from one mountain to the other in explaining the
history of distribution '(is).

The majority of British plants are identical with
species in Central and Northern Europe : of these,
some are among the most Avidely spread English
species, e.g. the Daisy and Primrose, while others,
such as the Oxlip {Prinvda elathr), are confined to
the Eastern counties, and others, such as the Cheddar
Pink {Dlanthus caesius), are restricted to Western
counties.

Before considering a small section of the British
flora which is the most interesting from the point of
view of origin, a short digression may be allowed in
order to call attention to the importance of a branch
of science which Darwin spoke of as 'that grand
subject, that almost keystone of the laws of creation,
geographical distribution,' and in 1847 referred to
as ' that noble subject of which we as yet but dimly
see the full bearing.' It was largely as the results

PROPERTY OF

Ai&M.COLLEGFURRARY,

II] GEOGRAPHICAL DISTRIBUTION 25

of his study of distribution in the Galapagos Islands
that Darwin determined to 'collect blindly every
sort of fact which bears anyway on what are species.'
The acceptance of the view^ 'that each species was
first produced within a single region '(19), raises the
subject of geographical distribution to a far higher
plane than it occupied in pre-Darwinian days. Al-
though most people are familiar with some of the
commoner means by which plants are able to colonise
new ground through the adaptation of their fruits and
seeds to various methods of transport, the conception
of a plant as a stationary organism tends to prevent
due allowance being made for the comparative
facility with which, in the course of successive
generations, a species is able to wander from place
to place. The individual animal is endowed with
powers of locomotion enabling it to seek new feeding-
grounds and to avoid enemies ; but with the
exception of some of the simplest forms a plant
cannot move — 'le niatin la laisse oii la trouve le
soir.' ^

The rate of travel may or may not be rapid, but
in a comparatively short time, if the conditions are
favourable, a tree may spread over a wide area.
Mr Ridley, Director of the Botanic Gardens, Singa-
pore, writes as follows in reference to the rate of
travel of one of the common Malayan trees {Shorea
leprosula), which bears Avinged fruits particularly

26 LINKS WITH THE PAST [ch.

well adapted to wind-transport : ' If we assume that a
tree flowers and fruits at 30 years of age and the fruits
are disseminated to a distance of 100 yards, that the
furthest fruits always germinate and so continue in
one direction, it will be seen that under such most
favourable circumstances the species can only spread
800 yards in 100 years, and would take 58,0(50 years
to migrate 100 miles '(20).

There is, however, one type of distribution —
wliat is called discontinuous distribution — to which
special attention should be directed on account of its
intimate association with questions relating to the
past history of living organisms. Many examples
might be quoted from both the animal and plant
kingdoms in support of the view that discontinuous
distribution is a criterion of antiquity. When identical
or very nearly identical plants occur in regions
separated from one another by areas in which the
particular species is unknown, the inference is either
that the surviving individuals are remnants of a large
number formerly distributed over a wider continuous
area, or that in the course of evolution similar con-
ditions in widely separated areas led to the production
of identical types. The former view is much the more
probable : it is consistent with the conclusions arrived
at on other grounds as to the connexion betAveen
discontinuous distribution and ancient lineage. The
explanations of the widespread occurrence among

II] GEOGRAPHICAL DISTRIBUTION 27

different races of similar objects or legends afford an
analogous case. As Dr Andrew Lang points out in
Custom and Myth, it is held by some students that
the use of the bull roarer — to cite a specific instance
— by different peoples denotes descent from a common
stock, though he considers the more probable ex-
planation to be that similar minds, working with
simple means towards similar ends, might evolve the
bull roarer and its mystic uses anywhere.

The Cedars of Lebanon afford an interesting ex-
ample of discontinuous distribution. They illustrate
how a species, which may be assumed to have
originated in one region, in the course of its
wanderings may undergo slight changes until, at
a later stage when the plants have disappeared from
parts of the once-continuous area, the remaining
outlying groups of individuals are spoken of under
different specific names. The cedars of Lebanon,
known as Cedrus llbanl, occur as isolated groups
on the Lebanon hills as outliers of the larger forests
of the Taunus 250 miles distant. The African cedar,
Cedrus atlantlca, is separated from the Lebanon
cedar by a distance of 1400 miles. Approximately
the same distance divides the Lebanon cedar from
the deodar, Cedrus deodara, which extends from
Afghanistan along the Himalayas almost to the
confines of Nepal. Sir Joseph Hooker regards the
three cedars as varieties of one species which once

28 LINKS WITH THE PAST [ch.

formed a continuous forest : he attributes the present
discontinuous distribution, in part at least, to the
effects of a warmer succeeding a colder climate. The
less favourable conditions drove the vegetation of
the lowlands to seek more congenial habitats at
higher altitudes. In this connexion it is interesting
to find that in Algeria the cedar is confined to the
higher ground where the snow lies long in the
spring(2i).

The Tulip Tree of North America and Central
China afibrds one of many examples of existing
flowering plants which illustrate the close connexion
between present distribution and past history. The
genus Liriodendron, often cultivated in the south
of England, is now represented by two species, the
best known of which — the Tulip Tree, Liriodendron
tidipera — extends from Vermont to Florida and
westwards to Lake Michigan and Arkansas. The
leaves . bear a superficial resemblance to those of
the Sycamore, but are as a rule easily distinguished
by the truncated form of the apex ; the specific name
was suggested by the tulip-like form of the flowers.
Fossil leaves of Liriodendron are not uncommon in
the Cretaceous rocks of Disco Island in latitude 70° N.,
where they occur Avith other flowering plants which
bear striking testimony to the mildness of the Cre-
taceous climate in high northern latitudes. One
of the associated flowering plants is a species of

II] GEOGRAPHICAL DISTRIBUTION 29

Artocarpiis, described by Dr Nathorst as Artocarpus
Dicksonl which bears a close resemblance to ^1. incisa
the bread-fruit tree of the southern tropics of the
Old World. Without attempting to deal fully with
the past history of Liriodendron, it may be confidently
stated that the records of the rocks are consistent
with the idea of antiquity suggested by the present
distribution of the two surviving species.

Islands such as Great Britain and Ireland, situated
a short distance from a continent, contain many plants
which are widely spread in different parts of the
world, together with a very small number peculiar
to the British Isles though closely allied to species
on the neighbouring , continent or to plants farther
afield. The occasional recognition of species pre-
viously believed to be confined to Britain tends to
reduce the short list of our endemic types.

An enquiry into the origin of an island flora
involves a consideration of the data in regard to
changes in level and relative distribution of land
and water in the course of geological evolution. It
is generally agreed that at no distant date, in a
geological sense. Great Britain and Ireland were
united to the continent. There is, however, another
fact to reckon with, namely the prevalence of Arctic
conditions in northern Europe when a thick sheet of
ice spread over the greater part of the British Isles.
There can be no doubt that the severity of the climate

30 LINKS WITH THE PAST [CH.

during the Glacial period was such as to destroy
a large proportion of the vegetation. The question
is, Avere all the flowering plants destroyed or were
some of the hardier species able to survive, either on
the higher peaks which kept their heads above the
level of the ice or on the southern fringe of England
beyond the ice-covered region ? It is impossible to
give a definite answer : the probability is that nearly
all the pre- Glacial species were destroyed, but it is
not impossible that some Alpine-Arctic plants escaped
extinction, while others retreated to more southern
and less Arctic areas by means of a land-connexion
with France or crossed the intervening sea by ocean-
currents, by animal agency, or by wind.

Although we possess but imperfect information as
to the extent and duration of land-bridges between
Britain and the continent, there are no special
difficulties in the way of accounting for the presence
of Scandinavian, Germanic, and other elements in the
British flora. There are, however, other and more
difficult problems to consider in reference to a small
group of flowering plants which are met with in the
west and south of Ireland, also, to a less extent, in
Cornwall and in a few other localities in the south-
west of England. In Connemara in the west of Ireland,
where hard frosts are unknown and winter snows are
rare, there are three kinds of Heath, St Dabeoc's Heath
(Dabeocia poli/olia), the Mediterranean Heath (Erica

II] GEOGRAPHICAL DISTRIBUTION 31

mediterrmiea) and Erica Maclaii Avhicli are not
found elsewhere in the British Isles or in the whole
of northern Europe, but reappear in the P3a'enees.
The London Pride (Saxlfraga umhrosa), another
Pyrenean plant, grows on the south and west coast
of Ireland from Waterford to Donegal. Arbutus
Unedo, the Strawberr}^ tree, which flourishes in the
Killarney district of County Kerry and occurs in
neighbouring localities, has a Avide distribution in
the Mediterranean region. Devonshire and Cornwall
possess two other Heaths, Erica ciliaris, which ex-
tends into Dorsetshire and occurs in north Brittany,
and Erica vagans, both Pyrenean species, while a
]\Iediterranean plant. Gladiolus illyriciis, grows in the
New Forest.

In 1846 Edward Forbes dealt with the problems
presented by the distribution of British plants in an
essay which has exercised a far-reaching influence.
When Forbes published his work, comparatively little
was known as to the possibilities of transport of seeds
and fruits across barriers of water (22). His conviction
that the known means of dispersal were insufficient
to account for the presence of Mediterranean or
Lusitanian plants in Ireland led him to turn to
geology for a solution of the problem. He was thus
led to put forward the view that in the course of
the Tertiary period when, as we know from palae-
ontological evidence, the climate of north and west

3-2 LINKS WITH THE PAST [cH.

Europe was iniich warmer than it is now, and long-
before the beginning of the climatic changes which
culminated in the (Jlacial period, there was a land-
connexion between the west of Ireland and the
south-w^est of the continent. Mr Praeger, whose
work on the Irish flora is well known to systematic
botanists, agrees with the conclusions of Forbes, and
sees in the Portuguese and Mediterranean plants
'relics of a vegetation which once spread along a
bygone European coast-line which stretched unbroken
from Ireland to Spain '(23). If this explanation is
correct it entitles Arbutus, St Dabeoc's heath and
other members of this southern group to be regarded
as a very old section of our flora. There is, however,
another side to the question : granting that a certain
number of Irish plants were able to w^ithstand the
rigours of an Ice age, it is hardly likely that the
strawberry tree and other southern types, which it
is admitted flourish in the south-west of Ireland
because of the mildness of the climate, w^ere of the
number of those which endured an extreme Arctic
phase. Moreover, if these Mediterranean species are
survivals from the Tertiary period, if they have been
isolated since pre-( glacial days as an outlier of a
southern flora, Ave might fairly expect that during
the long interval between their arrival and the
present day ncAV forms would have been produced
closely related to, though not identical with, the

II] GEOGRAPHICAL DISTRIBUTION 33

parent types. This, however, has not been proved to
be the case. Darwin in speaking of Forbes' Essay in
a letter to de CandoUe in 1863 says that he differs
from most of his contemporaries 'in thinking that
the vast continental extensions of Forbes, Heer, and
others are not only advanced without sufficient evi-
dence, but are opposed to much weighty evidence'(i2).
The alternative view is to regard Arbutus and its
compatriots as post- Glacial arrivals and not as sur-
vivals from a widely spread Tertiary flora.

A recently published account of the New Flora
of the volcanic island of Krakatau furnishes an
instructive and remarkable demonstration of the
facility with which a- completely sterilised island,
separated by several miles of ocean from neigh-
bouring lands, may be restocked with vegetation (24).
In 1883 the island of Krakatau, then densely covered
with a luxuriant tropical vegetation, was partially
destroyed by a series of exceptionally violent volcanic
explosions. After this catastrophe only a third of
the island was left : the surface was deeply covered
by pumice and volcanic ash and no vestige of life
remained. In 1906 a party of botanists who spent
a few hours on Krakatau collected 137 species of
plants : the vegetation was in places so dense that
it was with the greatest difficulty they penetrated
beyond the coastal belt, and some of the trees had
reached a height of 50 feet. The seeds and fruits

s. 3

34 LINKS WITH THE PAST [ch. ii

of this new flora have been carried by ocean-currents,
by wind, and by the agency of birds from other
islands in the ^lalay Archipelago. The nearest
islands, except the small island of Sebesi, about
12 miles distant, are Java and Sumatra, separated
from Krakatau by a stretch of water about 25 miles
in breadth. It is reasonable to wonder whether, had
Forbes known of this and similar modern instances
of the capabilities of plants as travellers, he would
have adopted the view he did. In this connexion it
may be added that in recent years the glaciation of
Ireland has been shown to be more extensive than it
was believed to be when Forbes wrote his essay.

There would seem to be no insuperable objection
to the conclusion that the Mediterranean plants in
Ireland and in the south of England reached their
present home after the retreat of the ice at the
end of the Glacial period, and after Ireland became
an island. A full consideration of the problem is
beyond the scope of this book, but I have briefly
stated the case, not with the authority of an expert
but in order to draw attention to a particularly
fascinating study in plant-migration.

In a volume by W. Canton entitled A ChikVs
book of Saints a story is told in which the presence
in Ireland of Mediterranean species receives a more
picturesque explanation. The Monk Bresal was sent
to teacli the brethren in a Spanish monastery the

Fig. 2, Eriocanlon septangulare With, West Conneniara.
(Photograph by Mr W. R. Welch.)

3—2

36 LINKS WITH THE PAST [CH.

music of Irish choirs. In later years Bresal longed
for a sight of his native land, though he loved his
home and ' every rock, tree, and flower " in his adopted
country. After returning to Ireland, his thoughts
reverted to Spain ; ' it appeared to him as though
he was once again in a granite nook among the rocks
beside the Priory ' ; he saw the ice-plant with its
little stars of white flowers sprinkled with red (the
London Pride) and a small evergreen tree from which
he had often gathered the orange-scarlet berries
(Arbutus). The Prior of the Spanish monastery ' with
heavenly vision saw Bresal gazing at the evergreen
tree and the ice-plaut, and turning to the trees
blessed them and commended them to go and make
real his dream. As Bresal brushed away his tears
he saw with amazement at his feet the ice-plant and
hard by the evergreen tree.'

The plant represented in Fig. 2 is another
British species which tasks the ingenuity of students
of plant-geography. This is the Pipe Wort {Erio-
canlon sejjtaugulare), the sole representative in
Europe of a certain family of Monocotyledons : it
flourishes in the west of Ireland and in the western
islands of Scotland but nowhere else in Europe ; it is
native on the other side of the Atlantic in Canada
and the northern United States of America. Mr
Praeger in describing the striking mixture of species
in the west of Ireland writes, ' The pool from which

II] GEOGRAPHICAL DISTRIBUTION 37

we gather the American Pipe Wort is fringed with
Pyrenean Heathers. The cracks which are filled with
the delicate green foam of the maiden hair are set in
Bearberry and Spring Gentian ; Hahenaria intacta,
far from its Mediterranean home, sends up its flower-
spikes through carpets of mountain Avens ; and
St Dabeoc's Heath and the dwarf Juniper straggle
together over the rocky knolls '(25).

The presence of Eriocaulon on the western edge
of Europe may be attributed to migration in pre-
Glacial days from North America by way of a land-
connexion, of which Greenland and Iceland represent
surviving portions. The opinion held by Forbes, and
advocated by some later naturalists, that the southern
companions of Eriocaulon in the west of Ireland are
survivors from a Tertiary flora which have lived
through the Ice Age, is consistently extended to the
Pipe Wort. On the other hand, before yielding to
the temptation to regard these American and Medi-
terranean species as links with the Tertiary period,
we must be convinced that the possibilities of
post-Glacial introduction, even without the aid of
land-bridges, have been exhausted. The Pipe Wort
is a botanical puzzle which affords a good example of
the accession of interest to field-botany effected by a
knowledge of the distribution of the component
members of the British flora. The problem of its
past history suggests an experimental enquiry into

38 LINKS WITH THE PAST [ch. ii

the adaptability of its seeds to dispersal, and em-
phasises the importance of the co-operation of
botanists and geologists in a common endeavour to
trace the origin of British plants.

In addition to the Pipe Wort, mention may be
made of three other American flowering plants
recognised in the Irish flora. Sisi/rinchiimi angusti-
folium recorded from the west of Ireland is native
in temperate North America ; the orchid, Spiranthes
romanzoffiana, met with in the south and north of
Ireland, is widely spread in Canada and the northern
States, while Sisyrinchium californiciiin, a native
of California and Oregon, was discovered by Mr Mar-
shall in marshy meadow-land near Wexford (26). In
the case of the more recently discovered American
immigrants, the possibility of human introduction
must be borne in mind, though there are no special
reasons for doubting that some, as in the case of Erio-
caulon, reached the Irish coast by natural agencies.

CHAPTER III

THE GEOLOGICAL RECORD

' All the Epochs of the Past are only a few of the front carriages,
and probably the least wonderful, in the van of an interminable
procession.' J. B. Bury {The Science of History).

The portion of the earth's surface accessible to
investigation is made up in part of accumulations
of old sediments, some indistinguishable from the
shingle, sand, and mud now in process of formation
by the ceaseless action of denudation ; others have
been hardened, gently folded or violently contorted
and so far altered by crust-movements as to render
their sedimentary origin well nigh unrecognisable.
It is these sediments of former ages, the dust of lost
continents, in which are preserved the majority of
the fragmentary remains of plants and animals, the
flotsam and jetsam of successive phases of evolution.

The crust of the earth, as Darwin wrote, ' with its
imbedded remains must not be looked at as a well
filled museum, but as a poor collection made at
hazard and at rare intervals '(19). It is from this

40 LINKS WITH THE PAST [ch.

imperfect record that we seek to discover the relative
antiquity of the several groups or genera of living
plants, and in the structure of extinct types we
endeavour to discover connecting links between
divisions of the plant kingdom which in the course
of evolution have retained little or no signs of a
common descent.

Sir Joseph Hooker in a letter to Darwin in 1859
speaks of his 'conviction that we have not in a
fossilised condition a fraction of the plants that have
existed, and that not a fraction of those we have are
recognisable specifically '(12). Considering the nature
of the palaeontological documents the wonder is how
much they have taught us, and we may look with
confidence to the results of future research in a field
of which tlie importance has only recently been
appreciated. With the strata of sedimentary origin
are frequently associated igneous rocks, and in many
continental regions, as in the majority of oceanic
islands, the crust of the earth consists wholly of
volcanic material or of rocks produced by the gradual
solidification of molten magmas. Rocks composed
mainly of carbonate of lime, such as limestones and
chalk, bear witness to ocean beds or to sediments
deposited on the floors of inland seas beyond the
reach of land detritus where coral reefs were reared
or the shells and other calcareous skeletons of
animals supplied the material for future land. In

Ill] THE GEOLOGICAL RECORD 41

such rocks the remains of calcareous seaweeds are
frequently recognisable and occasionally, as in the
English chalk, fragments of wood testify to transport
from a distant land.

While there is little difficulty in explaining the
nature of much of the earth's crust, in several parts of
the world the strata are totally unfossiliferous and
closely simulate crystalline rocks. In many cases
it is believed that such strata represent ancient
sediments which in the course of ages have been
reduced by metamorphic agencies to a condition
which has obscured or entirely obliterated all traces
of their pristine state.

Since the pioneer work of William Smith, who
in the early days of the nineteenth century first
realised the importance of fossils as aids to the
determination of relative age, geologists have devoted
themselves to the task of correlating the sedimentary
rocks of the world, using as criteria the order of
superposition of the strata and the nature of their
organic remains. The result has been to classify
portions of the earth's crust into periods or chapters,
which together constitute a record of geological
evolution as complete as it is possible to obtain from
the available data. The accompanying table shows
the order of sequence of the epochs, which stand for
terms of years of a magnitude beyond our powers to
grasp.

42

LINKS WITH THE PAST

[CH.

The division of geological history into larger and
smaller periods does not imply the recui-rence of
sudden revolutions ; it is in some measure dictated
by considerations of convenience, but more parti-
cularly by our ignorance of certain stages in the
history of the world due to the imperfection of the
record.

o^

' Recent

o
o

Pleistocene

PUocene

C5

Miocene

<

g

Oligocene

, Eocene

f

o

Cretaceous

1

1

Jurassic

<

o
o

Triassic

GEOLOGICAL TABLE.

Showing the position in the Geological Series of the strata referred
to in this volume.

Superficial accumulations containing human
remains (Metal age, Neolithic and Palaeo-
lithic ages, Glacial deposits)

Cromer Forest-bed, etc.

Absent from Britain.

Bovey Tracey beds, etc.

London Clay, etc.

( Chalk

I Wealden beds

( Purbeck and Portland beds (Upper Jurassic)
\ Oolites (Middle Jurassic)
[ Lias (Lower Jurassic)

(Rhaetic beds
Reuper ,, (Marls with rock-salt, etc.)
Bunter „

Ill] THE GEOLOGICAL RECORD 43

GEOLOGICAL TABLE (continued).

'' _ . ( Red Sandstones, etc.

Permian -;

i Magnesian limestone

Coal Measures

Carboniferous -| Millstone Grit

Carboniferous limestone

Devonian limestones, etc.

Devonian

Old Eed Sandstones

{

Slates, sandstones,

_., . f Sandstones, shales,

Silurian ^ ' '

some limestone

Ordovician , ^^ , ,

[ Volcanic rocks, etc.

Cambrian Slates, Sandstones, etc.

[ Slates, Volcanic rocks, etc.
V or Archaean j

In certain parts of the world, as for example the
north-west Highlands of Scotland, the Malvern Hills,
Scandinavia, and in many other regions in Europe
and North America, geologists have recognised what
they believe to be the foundation stones of the
world. These Archaean rocks, which underlie the
oldest fossiliferous strata, belong to a period of
geological evolution from which it appears to be
hopeless to obtain any light as to the nature of the
contemporary organic world. The earliest vestiges of
life so far discovered exhibit a high degree of organisa-
tion, which unmistakably points to their being links in
a chain extending far beyond the limits of the oldest

44 LINKS WITH THE PAST [cii.

Cambrian strata in which recognisable fossils first
occur. The rocks of the Cambrian and Ordovician
epochs, as represented by the grits, shales, slates
and other sedimentary strata in Wales, Shropshire, the
Lake district and elsewhere, though in places rich in
the remains of animals, aftbrd no information in regard
to the land vegetation. From the succeeding Silurian
epoch very little evidence has been gleaned as to the
nature of the flora, and it is not until we come to the
sedimentary rocks of the Devonian era that records
of plant-life occur in any abundance. The almost
complete lack of botanical data in the pre-Devonian
formations is in part due to the fact that these older
rocks consist to a large extent of marine deposits
formed under conditions unfavourable to the preser-
vation of plants. That the land-surfaces of the older
Palaeozoic eras supported an abundant vegetation
there can be little doubt. The relics of plant-life
furnished by the Devonian and succeeding formations
represent the upper branching-systems of a deeply
rooted and spreading tree, the lowest portions of
which have been destroyed or have left no sign of
their existence.

In descending the Geological series, we begin with
superficial deposits, such as peat and river-gravels
found subsequently to the underlying boulder-clay of
the Glacial period. The remains of forest trees pre-
served in the peat and in submerged forests round

Ill] THE GEOLOGICAL RECORD 45

the coast connect the vegetation of the historic period
with that of the Neolithic age. At the base of the
Pleistocene series, the name given to the latest
chapter of geological history, we find evidence of the
prevalence of arctic conditions in the Avidely spread
boulder-clays and other deposits of the Glacial period.

From deposits of post-Glacial date abundant plant
remains have been obtained, but we cannot say with
any degree of certainty what proportion of these
plants remained in Britain during the Ice age, and
whether the greater jiart of the vegetation, the relics
of which have been discovered in pre-Glacial beds,
was destroyed or driven south by the advancing ice.
We may briefly consider some of the more interesting
facts brought to light by the investigation of the
fossil plants in the Lower Pleistocene and Upper
Tertiary beds. It is mainly to the researches of
Mr Clement Reid into the vegetation of Britain
immediately preceding the Glacial period, that our
knowledge of this phase of the history of the British
flora is due.

On the coast of Norfolk in the neighbourhood of
Cromer the sections of the cliffs reveal the existence
of a succession of sands, clays, and gravels underlying
Glacial deposits ; this material was probably laid
down near the mouth of the ancient Rhine, which in
the latter part of the Tertiary period flowed across
a low area, which is now occupied by the shallow

46

LINKS WITH THE PAST

[CH.

southern half of tlie North Sea(27). The plant-
fragiiients found in these river-sediments indicate a

^

9*.r > ■

«<5^

i^ff^

Fig. 3. Pre-Glacial plants from Mundesley (A), Norfolk and Pakefield
(B, C), Suffolk. (Photographs by Mr Clement Keid and Mrs
E. M. Raid.) A. Bidens tripartita Linn. ( x 6) ; B. Picea excelsa
Linn. (nat. size). C. Stellaria holostea Linn. ( x 12).

Ill]

THE GEOLOGICAL RECORD

47

temperate climate. Among the plants of this pre-
Glacial flora are many familiar British species, such as
Caltha 2)alustris (marsh marigold), species of butter-
cup, Stellaria holostea (greater stichwort) (Fig. 3, C),
Bidens tripartita (bur-marigold) (Fig. 3, A), maple,

Fig. 4. Trapa natans Linn. (nat. size). From Mundesley.
(Photographs by Mr and Mrs Keid.)

hawthorn, the alder, hazel, the yew, Scots pine and
numerous others. If, as is not improbable, these
pre-Glacial plants were swept away by the subsequent
arctic conditions, the great majority of them returned
to their old home when a warmer climate ensued.

48 LINKS WITH THE PAST [ch.

There are however some pre-Glacial plants, such as
the spruce fir (Picea excelsa), a cone of which is
shown in Fig. 3, B, the water chestnut, Trapa natans
(Fig. 4), and a few other species no longer repre-
sented in the British flora. The genus Trapa is
a striking exanii)le of a flowering plant which has
disappeared since the Tertiary period from many
parts of Europe, including England, most of Sweden,
and from several regions in northern Europe. It still
grows in a few localities in Switzerland and in some
of the Italian lakes. In pre-Glacial times the water
chestnut was widely spread from Portugal and England
in the west to Siberia in the east, and its hard four-
pronged nuts have been recorded from many post-
Glacial peat-moors in the north of Europe.

From the so-called Cromer forest-bed and as-
sociated deposits on the Norfolk coast several
pre-Glacial plants have been obtained, indicating
a temperate climate during this phase of the
Pleistocene period. A few arctic species, such as
the dwarf birch and arctic willow obtained from the
deposits next above the Cromer forest-bed, herald
the near approach of glacial conditions.

It may be remarked in passing that no satisfactory
evidence has been discovered in Britain of the
existence of man in this part of Europe in pre-Gla-
cial days : it is, however, believed that flints from
Tertiary strata on the continent show traces of human

Ill] THE GEOLOGICAL RECORD 49

workmanship. As Sir Edwin Ray Lankester said in
1905, 'It is not improbable that it was in the remote
period known as the Lower Miocene — remote as com-
pared with the gravels in which Eoliths [primitive
stone implements] occur — that Natural Selection
began to favour that increase in the size of the brain
of a large and not very powerful semi-erect ape '(28).

Though comparatively recent in terms of geological
chronology, the remoteness, according to ordinary
conceptions of time, of the Tertiary period is brought
home to us when we endeavour to grasp the fact
that it was during this chapter in the earth's history
that some of our highest mountaiji-ranges, such as
the Alps, the Carpathians, and Himalayas were formed
by the uplifting of piles of marine sediments. From
Tertiary strata in the Isle of Wight, on the Hamp-
shire coast, and in the London basin numerous fossil
plants have been obtained, which afford convincing
evidence of climatic conditions much more genial
than those of the present day. The presence of palm
leaves and of a wealth of other sub-tropical plants
in Lower Tertiary beds in England reveals the
existence of a flora differing considerably both from
that in the uppermost Tertiary beds of Norfolk and
from the modern British flora, but closely allied to
the present Mediterranean flora.

The basaltic columns of the Giants' Causeway and
of the Staffa Cave, and the terraced rocks which form

s. 4

50 LINKS WITH THE PAST [ch. iii

so characteristic a feature in the contours of the
Inner Hebrides, arc portions of lava-floAvs, which in
the early days of the Tertiary period were poured
out over a wide area of land stretching from the
north-east of Ireland, through the Western isles of
Scotland, the Faroe islands, to Iceland and Greenland.
While in this northern region volcanic activity was
being manifested on a stupendous scale, a shallow
sea extended over part of what is now the south-
east of England in which was deposited a considerable
thickness of sedimentary material derived from the
neighbouring land. In this upraised sea-floor, known
as the London cl^y, which is exposed in the Isle of
Sheppey and in many other localities, numerous fossil
fruits and fragments of wood occur in association
with marine shells. The fact that many of the fruits
were ripe at the time of their entombment led some
eighteenth century writers to assign an autumn date
to the universal deluge. One of the Sheppey fruits
may be mentioned as an especially interesting sample
of the early Tertiary flora, namely the genus Nipa-
dites, so named from the very close resemblance of
the fossils to the fruits of the existing tropical plant
Nipa. Nipa frutlcaus, sometimes described as a
stemless palm because of the absence of the erect
stem which is usually a characteristic feature of
palms, grows in brackish estuaries of many tropical
countries (Fig. 5, A) : it has long leaves not unlike

52 LINKS WITH THE PAST [CH.

those of the date-palm and bears chisters of fruits
as large as a man's head ; a single fruit is two or
three inches long and its hard fibrous shell is charac-
terised b}^ four or five longitudinal ribs (Fig. 5, B).
The fruits of Nipa, Avhich may be carried a consider-
able distance by ocean-currents without losing the
power of germination, are constantly found with other
vegetable drift on the beaches of tropical islands. The
discovery of fruits of Nipa (or Nipadites), hardly
distinguishable from those of the existing species,
in Tertiary beds in England, Belgium, in the Paris
basin, and in Egypt afibrds a striking instance of
changes in the gQpgraphical distribution of an ancient
plant now restricted to warmer regions.

While the higher members of the Cretaceous
sj^stem, as seen in the chalk clifis and downs, re-
present the upraised calcareous accumulations on
the floor of a fairly deep and clear sea, the lower
members testify to shallower water within reach of
river-borne sand and mud. 'During the Chalk
period,' as Huxley wrote, 'not one of the present
great physical featui'es of the globe was in existence.
Our great mountain ranges, Pyrenees, Alps, Hima-
layas, Andes, have all been upheaved since the
chalk was deposited, and the Cretaceous sea flowed
over the sites of Sinai and Ararat ' (29).

The Wealden strata, at the base of the Cretaceous
system, as seen on the Sussex coast, in parts of the

Ill] THE GEOLOGICAL RECORD 53

Isle of Wight, in the Weald district of Kent and
neighbouring counties, point to the existence of a
lake over a portion of the south of England and of
the English Channel. The remains of a rich Wealden
flora have been collected from these Wealden sedi-
ments, notably from the plant-beds of Ecclesbourne
near Hastings, in which, so far as we know, flowering
plants played no part or at most occupied a very
subordinate position. A few fossil leaves have been
described from rocks assigned to a Wealden age,
— and from the older Stonesfield Slate, of Jurassic
age, a single leaf is recorded, — which seem to be
those of Dicotyledons ; but it is certain that even in
the early days of the Cretaceous period the present
dominant group in the plant kingdom was in its
infancy and in many regions probably unrepresented.
When we glance at the geological table and consider
that in all the floras from the Wealden down to the
Devonian period, flowering plants played no part,
we are able to appreciate the fact of their rapid
development, referred to in a previous chapter, when
once this highest type had become established.

The rocks comprised in the Jurassic system extend
from East Yorkshire to the coast of Dorsetshire ; they
consist of a succession of limestones, clays, sandstones,
and a few thin beds of impure coal. Sediments of
this age also occur, though to a much less extent,
on the north-east coast of Scotland and in a few

54 LINKS WITH THE PAST [ch.

places in the Inner Hebrides. Many of the Jurassic
strata contain only marine shells, and corals are
occasionally abundant, though in the lower members
of the system in the cliflfs near Lyme Regis and at
Whitby fossil plants are ftiirly common. It is, how-
ever, from the middle Jurassic beds, in the cliffs
between Whitby and Scarborough, and in some
inland quarries in East Yorkshire, that we have
obtained the richest Jurassic flora. Rivers from a
northern land laden with sediment and carrying drift-
wood, leaves and other plant fragments, deposited
their burden in an estuary which occupied the eastern
edge of Yorkshire. Sedimentary rocks laid down
towards the close of the Jurassic period in the island
of Portland in the south and on the Sutherland coast
in the north have furnished valuable records of
plant-life.

The passage from the Jurassic to the underlying
Triassic system is formed by some shales and lime-
stones in South Wales containing remains of fish and
other marine organisms. These so-called Rhaetic
beds are poorly represented in the British area, but
on the continent of Europe and in other regions the
sediments of this age bulk much more largely and
have yielded a rich collection of plants. The rocks
of the upper division of the Triassic system, as seen
in the Midlands, point to the prevalence of desert
conditions ; and in the grooved sand-polished surfaces

Ill] THE GEOLOGICAL RECORD 55

of granite in Charnwood forest we have a glimpse of
a Triassic landscape. The salt-bearing strata of this
period in Cheshire and Worcestershire suggest con-
ditions paralleled at the present day in the Caspian
and Dead-Sea regions. The vegetation of Britain, and
indeed of the Avorld as a whole, seems to have under-
gone but little change during the enormous lapse of
time represented by the sediments comprised between
the Wealden and Triassic periods. The Lower Triassic
flora affords evidence of a change in the facies of the
vegetation and prepares us for the still greater dif-
ferences revealed by a study of the Permian and
Carboniferous floras. To the student of evolution
these Palaeozoic floras are of special interest on
account of the facts they have contributed in regard
to the descent and inter-relationship of different
branches of the vegetable kingdom.

It is by a patient study of the waifs and strays
of the vegetation of successive phases of the world's
history preserved in sedimentary strata, that it has
been possible to follow the history of many existing
plants and to establish links between the present
and the past.

CHAPTER IV

PRESERVATION OF PLANTS AS FOSSILS

' Some whim of Nature locked them fast in stone for us after-
thoughts of Creation.' Lowell.

The failure of the earlier naturalists to grasp the
true significance of fossils or even to appreciate their
nature is an extraordinar}^ fact when we consider the
pioneer work which they accomplished in biological
and geological science. The following extract from
the writings of so enlightened a man as John Ray
serves to ilkistrate an almost incredible disinclination
to admit what seems to us the obvious. He wrote : —
'Yet I must not dissemble that there is a Pheno-
menon in Nature, which doth somewhat puzzle us to
reconcile with the prudence observable in all its
work, and seems strongly to prove, that Nature doth
sometimes ludere, and delineates figures, for no other
end, but for the ornament of some stone, and to
entertain or gratify our curiosity, and exercise our
wits. This is, those elegant impressions of leaves and

CH. IV] PRESERVATION OF PLANTS 57

plants upon cole- slate, the knowledge of which,
I must confess myself to leave to my learned and
ingenious friend Mr Edward Lhwyd of Oxford.... He
told me that Mr Woodward, a Londoner, shewed
him very good draughts of the common female fern,
naturally formed in cole.... But these figures are more
diligently to be observed and considered... Dr Wood-
ward will have them to be the impressions of the
leaves of plants which were there lodged at the time
of the Deluge '(31).

The Mr Woodward alluded to by Ray thus
expressed his views on fossils in an Essay towards
the Natural History of the Earth : — ' The whole
terrestrial globe was taken all to pieces and dissolved
at the Deluge, the particles of stone, marble, and
all solid fossils dissevered, taken up into the Avater,
and then sustained together with sea shells and other
animal and vegetable bodies ; the present earth
consists and was formed out of that promiscuous mass
of sand, earth, shells, and the rest falling down again,
and subsiding from the water ' (32).

In the later part of the seventeenth century
Steno, a Dane by birth and Professor of Anatomy at
Padua, by his recognition of the identity of the teeth
in a shark's head, which he had dissected, with some
fossils from Malta known as Glossopetrae, established
the true nature of fossils. He also recognised a
certain orderly sequence in fossiliferous strata, and

58 LINKS WITH THE PAST [ch.

in the opinion of Professor Sollas he is entitled to
be considered the 'Father and Founder' of Geology (33).

It was by slow degrees that the early observers
freed themselves from the obsession that the remains
of animals and plants in the earth's crust bear witness
to a Universal Deluge and are all identical with
existing species. The possibility that some of the
fossil plants in English strata might be more clearly
related to forms now met with in Avarmer regions
was gradually realised. The publication of the
Origin of Species stimulated palaeontological
research, and botanists as well as zoologists turned
to the investigation of extinct genera in search of
proofs of the doctrine of evolution.

The common occurrence of petrified wood in
rocks of diflferent ages is well known. Fossil stems
are occasionally found in their natural position of
gi-owth, the structural details being rendered perma-
nent by the deposition of siliceous or calcareous
material from water drawn by capillarity into the
dead but still sound tissues. Petrified wood from
Upper Jurassic beds is abundant in the Island of
Purbeck ; an unusually long piece of stem may be
seen in the small town of Portland fixed to the wall
of a house. Some of these stems have been referred
by an American author to the Araucarian family of
Conifers, but the structure is as a rule hardly well
enough preserved to afibrd satisfactory evidence for

IV] PRESERVATION OF PLANTS 59

identification. In his Testimony of the RocJcs, Hugh
Miller speaks of fossil wood from the upper beds of
the Jurassic system in sufficient abundance on the
beach at Helmsdale in Sutherlandshire to be collected
in cart-loads ; it is still easy to pick up good speci-
mens on the shingle beach a short distance north of
Helmsdale, and a recent microscopical examination
showed that some specimens are pieces of an Arau-
carian tree.

Impressive examples of petrified trees on a
large scale are to be seen in the United States,
in Arizona and the Yellowstone Park. (Frontispiece.)
In the northern part of Arizona the country for over
an area of 10 square miles is covered with tree trunks,
some reaching 200 feet in length and a diameter of
10 feet. The nature of the mineralising substance has
given rise to the name Chalcedony Park for this
Triassic forest (34). A striking example of one of the
Arizona trees is exhibited in the British Museum and
in a neighbouring case is a splendid petrified stem, 9 ft.
in height, of a conifer discovered in Tertiary lavas in
Tasmania (35).

Figure 6 illustrates the preservation of a series
of forests of Tertiary age in the mass of volcanic
sediments, 2000 feet in thickness, known as Amethyst
mountain, in the Yellowstone Park district. By the
Aveathering away of the surrounding volcanic material
the tall stems of the trees are exposed in places on

Fig. 6. Section of the north face of Amethyst Mountain, Yellow-
stone Park, including upwards of 2000 ft. of strata. The
steepness of the slope is exaggerated. (After W. H. Holmes.)

OH. IV] PRESERVATION OF PLANTS 61

the mountain sides like the 'columns of a ruined
temple.' The height of the river at the foot of the
chff is 6/00 ft. above sea-level and the mountain
rises to a height of 9400 ft. above the sea. In the
lower part of the section the volcanic strata are seen
to rest on a foundation of older rocks A, and these
in turn were laid down on the eroded surface of a
still more ancient foundation, J5(36).

The section as a whole affords a striking demon-
stration of the magnitude of earth-movements since
the last of these forests was buried below the
surface of a sea in which the volcanic material was
deposited. The account of the Yellowstone Park
section recalls Darwin's description in the Natural-
ises Vo I/age (.S7) of snow-white columns projecting
from a bare slope, at an altitude of 7000 ft. in the
Cordillera.

The abundance of drift wood on the coasts of
some countries at the present day helps us to picture
the conditions under which the remains of former
forests have been preserved. In his Letters from
High Latitudes, Lord Dufferin gives the following
description of drift-wood on the shores of Spitz-
bergen : — ' A little to the northward, I observed,
lying on the sea-shore innumerable logs of drift-wood.
This wood is floated all the way from America by the
Gulf Stream, and as I walked from one huge bole
to another, I could not help wondering in what

62 LINKS WITH THE PAST [ch. iv

primeval forest each had grown, what chance had
originally cast them on the waters, and piloted
them to this desert shore 'os). A photograph re-
produced in Amundsen's book on The North West
Passage shows the beach on the Alaskan coast
strewn with drifted timber (39). For the accompanying
photograph (Fig. 7) of the flood-plain of the Colorado
River (40), I am indebted to Professor MacDougal of
the Desert Research Laboratory at Tucson, Arizona,
who in a recent letter writes, ' During times of high-
water a thin sheet of flood covers the flat for many
miles and bears drift-wood so thickly that it is
difficult to push a boat through it.' The drift-wood
consists of poplar, willow, pine, and juniper, ' the last
two have been brought from the upper river, from
as far away as a thousand miles.' A picture such as
this affords an admirable example of the wealth
of material available for preservation in a fossil state.
It is only in the minority of cases that the
accidents of preservation of fragments of ancient
floras have given us the means of investigating the
internal structure of the plant organs. It is far more
frequently the case that fossil plants are represented
only by a carbonised film on the surface of a piece of
shale or other rock : the actual substance of the
plant has been converted into a thin layer of coal,
and though the venation and other surface-features
may be clearly revealed, the internal tissues have

Fig. 7. Flood-plain of the delta of Kio Colorado. The hills in
the background are 25 miles distant. (From a photograph by
Prof. MacDougal.)

64 LINKS WITH THE PAST [ch.

been destroyed. If a lump of clay containing a
piece of fern frond is heated, the result is an im-
pression of the leaf on the hardened matrix and a
coaly substance in place of the plant substance. It
is occasionally possible by detaching a piece of the
black film from a fossil, and heating it with nitric
acid and chlorate of potash and then dipping it in
ammonia, to obtain a transparent preparation suitable
for microscopical examination of the cell-outlines
of the superficial layer of the leaf or other plant-
fragment. This method of examination, used by
several students of fossil plants and with conspicuous
success by Professor Nathorst of Stockholm, often
affords valuable aids to identification.

Pieces of plants embedded in sandy sediment,
if not preserved by petrifaction, that is by the
introduction into the tissues of some siliceous
or calcareous solution, gradually decay and their
fragmentary remains may be washed away by
percolating watei', leaving a hollow^ mould in the
gradually hardening sediment, which is afterwards
filled with sand or other material. The plant itself
is destroyed, but a cast is taken which in the case
of fine-grained sediments reproduces the form and
surface-pattern of the original specimen. The in-
crustation of plants by the falsely named petrifying
springs of Knaresborough and other places illustrate
another method of fossilisation.

IV]

PRESERVATION OF PLANTS

65

Plants which owe their preservation to amber
occur both as incrustations and petrifactions. This
fossil resin occurs in Tertiary, Cretaceous, and
Jurassic rocks ; the amber found in abundance on
the Baltic coast near Danzig and occasionall}^ picked
up on the beach in Norfolk and Suffolk comes from

Fig. 8. Flower of Cinnamoum prototypum Conw. preserved in
amber. x 10. (After Conwentz.)

beds of Tertiary age. Pieces of Pine-wood have been
described from the Baltic beds in which the tissues
are perfectly preserved as the result of the conversion
into amber of the resinous secretion which permeates
their cells : in this case the amber is a petrifying
s. 5

66 LINKS WITH THE PAST [ch.

agent. More frequently the preservation is due to
incrustation ; as resin trickled down the stems of the
Tertiary pines from an open wound, flowers and
leaves, blown by the wind on to the sticky surface,
were eventually sealed up in a translucent case of
amber. Though the actual substance may have gone,
the mould which remains exhibits in wonderful per-
fection each separate organ of a flower or the
delicate hair-clusters on the surface of a leaf. The
flower represented in Fig. 8, a species of Cinnamon,
is one of several specimens described by tlie authors
of a monograph of Tertiary plants in the Baltic
amber{4i).

The fragments of plants preserved in nodules of
calcareous rock occasionally met with in some of the
Lancashire and Yorkshire coal-scams are perhaps
the most striking examples of the possibilities of
petrifaction. By cutting sections of these nodules
and grinding them to a transparent thinness, the
most delicate tissues of Carboniferous plants are
rendered accessible to investigation under the high
power of a microscope. As our attention is absorbed
by the examination of the details of cell-structure
it is easy to forget that the section has not been
cut from a living plant, but from the twig of a
tree which grew in the forests of the Coal age. The
preservation is such as to enable us not only to
describe the anatomy of these extinct types of

IV] PRESERVATION OF PLANTS 67

vegetation, but, by the application of the knowledge
of the relation between the structure of the plant-
machine and its functions gained by a study of living
species, it is possible in some degree to picture the
plants of the Coal period as living organisms and
to see in the structural framework a reflection ot
external environment. The recognition in the general
architectural plan of the Palaeozoic plants, as in
many of the finer anatomical features, of the closest
resemblance to plants of the modern world produces
an almost overwhelming sense of continuity between
the past and the present.

The plants of the Palaeozoic period, though often
diffbring considerably from those of the same class
in the floras of to-day, exhibit a remarkably high type
of organisation. Some of the most abundant trees in
the forest of the Coal age are decidedly superior
in the complexity of their structure, as also in
size, to modern survivals of the same stock. On
the other hand, it must be remembered that Mono-
cotyledons and Dicotyledons which now occupy the
highest place in the hierarchy of plants have left no
sign of their existence in any of the Palaeozoic strata.
The greater size of some of the Palaeozoic plants,
and in some respects the more advanced stage of
evolution which they represent as compared with
their nearest relatives of the present era, must be
considered in relation to their more important and

5—2

68 LINKS WITH THE PAST [ch.

relatively higher position in the plant-world than
that which is now held by their diminutive de-
scendants. It is, however, impossible to get away
from the conclusion that the oldest Palaeozoic floi'a
of which we have an intimate knowledge must be
the product of development of an age which is
represented by a chapter in the history of the plant
kingdom at least as far removed from the beginning
as it is separated from the chapter now being written.
Examples might be quoted in illustration of the risks
attending the determination of fossils by means of
external features alone, but it may suffice to mention
the case of a specimen originally described as a
fragment of a Cretaceous Dinosaur under the name
AacJienosmiriis multidens. By the examination of
thin sections this supposed bone was shown to be
a piece of Dicotyledonous wood (42). The methods of
preservation of plants as fossils are numerous and
varied and the few examples selected give but an
incomplete idea of the subject : for a fuller treatment
of fossilisation the reader is referred to more technical
treatises (48 vol. i.).

The employment of fossil plants as ' Thermometers
of the ages ' is a branch of Palaeobotany to which a
passing allusion may be permitted though it is only
indirectly connected with the main question. As
one of the most interesting examples of changed
climatic conditions revealed by a study of fossil plants,

IV] PRESERVATION OF PLANTS 69

reference may be made to the wealth of material
collected within the Arctic circle. The problems
suggested by the discovery of plants in rocks of
various ages in North Siberia, Spitzbergen, Franz
Josef Land, Bear Island, Greenland, and in many
other localities in the far north are too difficult
and far-reaching to be discussed in these pages. In
the Cretaceous and Tertiary strata of the west coast
of Greenland and Disco Island from 69° to 72° north
latitude, to refer only to one case, a great number
of plants have been obtained by several of the earlier
Arctic explorers and more recently by members of
one of the Peary Expeditions. At the present day
on the fringe of land on the western edge of Green-
land which is not permanently covered with ice,
a considerable number of herbaceous plants are able
to exist and to produce seed during their concentrated
period of development ; while trees are represented
only by a few low-growing shrubs such as the dwarf
Juniper. In places accessible to investigation beyond
the ice-covered hills of northern Greenland the rocks
have been shown to consist of Cretaceous and Tertiary
sediments containing fossil plants associated with
seams of coal. From these beds numerous Dicotyle-
dons have been obtained, some of them almost
identical with living species characteristic of sub-
tropical or tropical countries. In the lowest of the
Cretaceous series no Dicotyledons have been found,

70 LINKS WITH THE PAST [ch. iv

but flowering plants are abundant in the higher
Cretaceous rocks. Allowing for the fact that closely
allied species are often able to live under very
different climatic conditions, there can be no doubt
that the Cretaceous and Tertiary floras of Greenland
indicate an average temperature considerably higher
than that which now prevails in the warmest parts
of the British Isles.

In the far south a fairly rich Jurassic flora has
recently been discovered by the members of a
Swedish Antarctic expedition in Graham's Land in
latitude 63°-15 S. and longitude 57° W., which in its
general facies bears a close resemblance to the
Jurassic flora of Yorkshire.

Although the great majority of the records of
ancient plants are difficult to interpret by reason
of imperfect preservation and because of the frequent
separation of leaves, stems, and reproductive organs,
the student who tries to piece together the disjecta
membra of the floras of the past shares the opinion
expressed by the late Marquis of Saporta, — ' Si Ton
s'attache a les dechiffrer, on oublie bien vite la
singularite des caracteres, et le mauvais t^tat des
pages. La pensee se l^ve, les idees se developpent,
le manuscrit se deroule ; c'est la tombe qui parle et
livre son secret.'

CHAPTER V

FERNS; THEIR DISTRIBUTION AND ANTIQUITY

' It has been shown that certain forms persist with very little
change, from the oldest to the newest fossiliferous formations ; and
thus show that progressive development is a contingent, and not
a necessary, result of the nature of living matter.' Huxley.

The Ferns as a whole represent a section of the
vegetable kingdom which traces its ancestry as far
into the past as any group of plants. Impressions of
leaves on the shales of the Coal-measures and on
rocks of the earlier Devonian period are hardly
distinguishable in form and in the venation and
shape of the leaflets from the finely divided fronds
of modern ferns. Until a few years ago these
Palaeozoic fossils were generally regarded as true
ferns, and it was believed that ferns played a con-
spicuous part in the vegetation of the earliest periods,
of which we have any botanical knowledge. Con-
clusions based on external form must frequently be

n LINKS WITH THE PAST [ch.

revised in the light of more trustworthy evidence.
It was shown in the later part of the nineteenth
centur}^ by the late Professor Williamson of Man-
chester, whose researches into the plants of the
Coal age shed a flood of light on the ancestry and
inter-relationship of many existing plants, that some
of the fern-like leaves which have long been familiar
to those who search among the shales of the refuse
heaps of collieries, were borne on stems differing in
anatomical features from those of any known fern.
The investigation of the structure of the leaves and
their supporting stems led to the recognition of
certain extinct genera of Palaeozoic plants of excep-
tional interest, to which the term generalised type is
aptly applied. Associated with anatomical and other
characters such as we now regard as the attributes
of ferns, these plants exhibit other features not met
with in modern ferns but characteristic of a group of
seed-bearing plants known as the Cycads. Recent
research has revealed the existence of several such
generalised types which, by their combination of
characters now met with in distinct sub-divisions
of the plant-kingdom, clearly indicate the derivation
of Ferns, and Cycads as we know them to-day, from
a common stock. It was in the first instance by
means of anatomical evidence — obtained by the
microscopical examination of sections of petrified
fragments of stems and leaves — that the generalised

V] FERNS 73

nature of these Palaeozoic plants was recognised.
Nothing was known as to the reproductive organs.
Ferns as now represented in the floras of the
world are essentially seed-less plants. As the author
of Hudihras wrote :

' Who would believe what strange bugbears
Mankind creates itself, of fears?
That spring like fern, that insect weed,
Equivocally, without seed.'

The reproductive organs or spores borne on the
fronds of a fern produce, on germination, a thin
green structure, known as the prothallus, less than
an inch in length : this bears the sexual organs, and as
the result of the union of the male and female cells,
the embryo fern-plant begins its existence as a parasite
on the inconspicuous prothallus, until after unfolding
its first green leaf and thrusting a slender root into
the ground, it starts its career as an independent
organism \ In this life-cycle the seed plays no
part.

It is noteworthy that the absence of any indication
of spore-capsules and spores, in the case of some of
the supposed fern leaves from the Coal-measures,
caused some suspicion in the mind of an Austrian
Palaeobotanist as to the right of such specimens to

^ The life-history of a Fern is clearly described by Prof. Bower
in a recent volume in this series.

74 LINKS WITH THE PAST [ch.

be classed among the ferns. This opinion, based in
the first place on negative evidence and but little
regarded by other authors, has in recent years
been proved correct. In 1904 a paper was read
before the Royal Society by Professor Oliver and
Dr Scott(43) in which evidence was brought forward
pointing to the conclusion that one of these
generalised plants bore true seeds. Subsequently
Dr Kidston published an account of some specimens
of another of these Palaeozoic plants in which was
actually shown an organic connexion between un-
doubted seeds and pieces of a fern-like frond (44).
Without entering into further details, these and
similar discoveries may be summarised as follows : —
Many of the supposed Fern -fronds of Palaeozoic
age, particularly those characteristic of the Coal-
measures, are the leaves of plants which in their
anatomical characters combined features now shared
by true Ferns and by the Cycads. The reproductive
organs of these Palaeozoic genera differed widely
from those of existing ferns ; the male organs, while
not unlike the spore-capsules and spores of certain
ferns, recall the male organs of living Conifers and
Cycads, and the female organs were represented by
seeds of a highly complex form. These seed-bearing
plants have been called Pteridosperms, a name
which expresses the combination of fern-like features
with one of the distinguishing attributes of the

v] FERNS 75

higher plants, namely the possession of seeds. The
ancestors of Pteridosperms are as yet unknown ; it
is, however, reasonable to assume that there existed
in some pre-Carboniferous epoch a group of simple
plants from which both Ferns and Pteridosperms
were derived. In the forests of the Coal age true
Ferns probably occupied a subordinate position in
relation to the Pteridosperms.

The question of the relationship between different
families of recent ferns and the older known fossil
members of the group is beyond the scope of this
book. Evidence has been discovered in recent years
which warrants the statement that, although none of
those Carboniferous ferns were generically identical
with existing forms, they very clearly foreshadowed
some of those structural features which characterise
more than one family of present-day Ferns. The
records of the older Mesozoic formations afford
abundant evidence of the existence of certain types
of Ferns showing a very close resemblance to recent
species.

An enquiry into the geographical distribution of
living Ferns reveals facts of special interest in
connexion with the relative antiquity of different
genera and families. The wide distribution of the
Bracken fern has already been referred to : it is
abundant in Tasmania ; its vigour in the island
is well illustrated by Mr Geoffrey Smith's statement

76

LINKS WITH THE PAST

[CH.

Fig, 9. Osmunda regalis Linu. Fertile frond, (f nat. size.)

v] FERNS 11

that constant attention is necessary to keep it from
invading newly opened country (45). On Mount Ophir
in the Malay Peninsula the cosmopolitan bracken
occurs in association with the two genera Matonia
and Dipteris, ferns which are among the most striking
examples of links with a remote past and have a
restricted geographical range. With Osmunda re-
galis, the Royal Fern, the Bracken is conspicuous
in the marsh vegetation of the Bermudas ; it flourishes
on the Atlas INIountains, in the Canary Islands, in
Abyssinia, on Mt Kenia, in British East Africa, in
the Himalayas, and is in fact generally distributed in
the tropics in both the north and south temperate
zones.

The Royal Fern (Fig. 9) is another British species
with a wide distribution ; it occurs in Northern Asia
and in North America ; it is common in the Siberian
forests and lives in several tropical countries, ex-
tending to Southern India and Cape Colony, and in
South America it is represented by a closely allied
species. Though at the present day Osmunda regalis
is one of the rare English Ferns, its occurrence in the
submerged forest-beds round our coasts and in pre-
Glacial beds points to its former abundance in the
British area generally. The Royal Fern is a member
of a family now represented by two genera, Osmunda
and Todea.

With the exception of Todea harhara, with its

78 LINKS WITH THE PAST [ch.

large spreading fronds and a short root-covered stem,
which occurs in Australia and Cape Colony, all the
species of this genus are filmy ferns with semi-
transparent fronds adapted to a moisture-laden
atmosphere. -O410 filmy opooion of Todea is repre-
sented in tho Brititfli lima b) Toden mdwans in
the Killatne) di.'^tiict uf Ireland ; but the maximum
development of the genus is in New Zealand.

Todea harhara affords an instance of discontinuous
distribution ; it was no doubt once widely spread in
circumpolar regions and noAV survives only in South
Africa and in Australia.

There are satisfactory reasons for regarding the
Bracken Fern, with its world-wide range in present-
day floras, as a comparatively modern species now in
full vigour. Its anatomical and other features are
consistent with the view that it is a late product of
evolution, and as yet no indication has been given by
the records of the rocks of an ancient lineage. The
Osmunda family, on the other hand, is undoubtedly
an extremely old branch of the fern group. A com-
parison of the Royal Fern with the Bracken shows
that their stems are constructed on very different
plans, and we have good reasons for speaking of the
structural peculiarities of the former as those of
a more primitive type. Moreover, the discontinuous
geographical range of some members of the Osmunda
family is in itself an indication of antiquity. There

V] FERNS 79

is another point which may have a bearing in this
question of antiquity, namely the fact that the spores
of Osmunda are green and do not possess the powers
of indurance inherent in the spores of the majority of
ferns which are not green. It has recently been con-
tended by Professor Campbell of Stanford University
that the delicate green spores of the Liverworts,
plants closely allied to the Mosses, constitute an
argument in favour of the antiquity of these plants (46).
Certain Liverworts are cosmopolitan in their range,
e.g. the genera Riccia and Marchantia.

If certahi genera are widely distributed, notwith-
standing the fact that their reproductive cells, by
which dispersal is effected, are ill-adapted to withstand
unfavourable conditions or to endure prolonged
desiccation, it would seem reasonable to conclude
that their emigration has been accomplished slowly
and with difficulty. Ferns such as Osmunda, with
green and short-lived spores, would thus be handi-
capped in competition with other genera provided
with more efficient means of dispersal and better
equipped for the vicissitudes of travel.

The inferences as to antiquity deduced from a
study of the existing species of Osmunda and Todea
receive striking confirmation from the testimony of
fossils. Some of the oldest known Palaeozoic ferns,
though differing too widely from the existing Osmundas
and Todeas to be included in the same family, afford

80 LINKS WITH THE PAST [ch.

distinct glimmerings of Osmundaceous characters,
which at a hiter period became individiiahsed in
the direct ancestors of the modern forms. Our
knowledge of the past history of the Osmnnda famil}^
has recently been considerably extended and })laced
on a firmer basis by the researches of I)r Kidston
and Professor Gwynne-Yaughan. These authors have
recognised in some exceptionally well-preserved fern-
stems from Permian rocks in Russia, anatomical
features which point unmistakably to close rela-
tionship Avith the recent members of the family (47) (48).

Passing higher up the geological series, fertile
fern fronds with spore-capsules and spores practically
identical with those of Osmnnda have been found in
the Jurassic plant-beds of Yorkshire and in rocks
of approximately the same age in many parts of the
world. From Jurassic strata in New Zealand a
petrified fern-stem has been described (OsmuudUes
Dnnlo}ji), almost identical in structure with the
surviving species. Cretaceous and Tertiary examples
of similar ferns might be cpioted ; but enough lias
been said to establish the claim of the Royal Fern
and other members of the Osmunda-family to an
ancestry which possibly extends even farther back
than that of any other existing family of Ferns.

A brief reference may be made to another fern now
represented by several species widely disseminated
in tropical and sub-tropical countries. The genus

V]

FERNS

81

Gleichenia occurs abundantly in the warmer regions
of both the Old and New World. The fronds may
usually be recognised by their habit of growth
(Fig. 10) ; in several species the main axis is

Fig. 10. Gleichenia dicarpa Br. {h nat. size.)

repeatedly forked and a small bud between the

divergent branches of the forks forms a characteristic

feature. The leaflets are either long and narrow

s 6

82 LINKS WITH THE PAST [ch.

like the teeth of a comb or short and bhmtly rounded.
Moreover the anatomy of the creeping stem affords
a ready means of identification. We have satisfactory
evidence of the occurrence of Gleichenia in European
floras during both the Jurassic and Cretaceous
periods. Numerous fragments of plants were obtained
some years ago, not far from Brussels, from the Wealden
strata in which the famous skeletons of Iguanodon
were discovered. Visitors to the Natural History
Museum in Brussels are no doubt familiar with the
skeletons of this enormous herbivorous animal : in
the same gallery are exhibited the remains of the
fossil plants from the Iguanodon beds. Some of
these fragments are pieces of fern fronds identical
in form with those of existing Gleichenias. The
microscopical examination of some exceptionally well
preserved fragments of Wealden stems discovered by
Prof. Bommer of Brussels enabled him to recognise
the Gleichenia type of structure and thus to confirm
the inconclusive evidence furnished by fragmentary
leaves. The most interesting records in regard to
the former occurrence of Gleichenia in Northern
Europe we owe to the late Oswald Heer of Zurich,
who has described many examples of Gleichenia
fronds from rocks of Lower Cretaceous age in
Disco Island on the west coast of Greenland in
latitude 70° N. The same type of fern is recorded
also from upper Jurassic beds in the north-east of

v] FERNS 83

Scotland, in the Wealden rocks of Sussex, as well as
from other European localities. It is clear that the
Gleichenia-family, no longer represented in north
temperate floras, was in the Jurassic period, and
especially in the early days of the Cretaceous period,
widely spread in Europe, extending well within the
Arctic circle. It may be that the original home of
Gleichenia was in the far North at a time when
climatic conditions were very different from those
which now prevail. Gleichenia, like many other
northern plants, retreated to more southern regions
where, in the warmer countries of the world, many
species still flourish widely separated in space and
time from the place of their birth.

The ferns so far mentioned have a more or less
extended distribution at the present day. In the
case of Pteridium aquilhmm, the cosmopolitan
Bracken Fern, wide range Avould seem to be corre-
lated with comparatively recent origin ; on the
other hand, the facts of palaeobotany show that
the wide distribution of Osmunda, a type of fern
which differs in many important respects from
members of the family (Folypodiaceae) to which
the Bracken belongs, is not inconsistent with an
exceptionally ancient family-history. There are,
however, certain genera of ferns which afford
remarkable examples of restricted geographical
distribution associated with great antiquity. The

6—2

84 LINKS WITH THE PAST [ch.

island of Juan Fernandez, 420 miles oflf the coast
of Chili, the home for four years of Alexander
Selkirk (to whose adventures we owe Defoe's
creation of Robinson Crusoe), is interesting also
from a botanical point of view. The vegetation of
this oceanic island, 20 square miles in area with
basaltic cliffs rising to a height of 3000 ft. above
the sea, includes more than 40 species of ferns,
eight of which occur nowhere else. One of these
endemic ferns is Thyrso2:tteris elegans, the only
representative of the genus ; it is readily distinguished
by its large and graceful fertile fronds, examples of
which may occasionally be seen on a plant of this
species in the Royal Gardens at Kew : the sporangia
are produced in circular cups which replace the
ordinary leaflets on the lower branches of the frond
and hang from the short axis like miniature clusters
of grapes. It is noteworthy that among the frag-
mentary remains of the fern vegetation of the Jurassic
flora in England and in other parts of Europe
specimens occur with fertile segments practically
identical with those of the Juan Fernandez species.
Students of fossil plants are occasionally led away
by the temptation to identify imperfect specimens
with rare existing species to which they exhibit a
superficial resemblance, and this is well illustrated
by tlie frequent use of the generic name Thyrsopteris
for Jurassic and Lower Cretaceous ferns which are

v] FERNS 85

too imperfect to be determined with any degree of
certaint}^ We have, however, satisfactory grounds
for the assertion that the Juan Fernandez fern
affords a striking confirmation of the truth of
Darwin's dictum that 'Rarity, as geology tells us,
is the precursor to extinction.' In this remote oceanic
island, for reasons which we cannot explain, there
lingers an isolated type which belongs to another age.
The following passage, which forms a fitting
introduction to an account of two other genera of
ancient ferns, is taken from a description of an
ascent of Mount Ophir in the Malay Peninsula by Dr
A. R. Wallace in his well-known book on the Malay
Archipelago : — ' After passing a little tangled jungle
and swampy thickets, we emerged into a fine lofty
forest.... We ascended steadily up a moderate slope
for several miles, having a deep ravine on the
left. We then had a level plateau or shoulder to
cross, after which the ascent was steeper and the
forest denser till we came out upon the Padang-
Batu, or stone-field.... We found it to be a steep
slope of even rock, extending along the mountain
side farther than we could see. Parts of it were
quite bare, but where it was cracked and fissured
there grew a most luxuriant vegetation, among which
the pitcher plants were the most remarkable.... A few
coniferae of the genus Dacrydium here first appeared,
and in the thickets, just above the rocky surface,

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[CH.

we walked through groves of those splendid ferns,
Dipteris Horsjieldu and Matonia 2)(^ctmata, which

Fig. 11. Matonia 2)ectinata. A group of plants in a wood on
Gunong Tundok, Mount Ophir. (Photograph by Mr A. G. Tansley.)

bear large spreading fronds on slender stems, 6 or
8 feet high '(49).

V] FERNS 87

The two genera Matonia and Dipteris afford
exceptionally striking examples of survivals from
the past. Matonia is represented by two species,
Matonia jyectinata (Fig. 11), which grows abundantly
on the upper slopes of Padang Batu in dense thickets
on the rock faces where, as Mr Tansley states, its
associates are a species of Gleichenia, Dipteris,
and a little Pterldmm aquilimim (Bracken Fern).
3Iafoma pectinata occurs also on Bornean mountains
at an altitude of over 3000 ft. and descends to the
coast on some of the Malay islands. The other
species of the genus, Matonia sarmeutosa, has so
far been found in one locality only, Mak, Sarawak,
where it was discovered by Mr Charles Hose.
Matonia pectinata has a creeping stem covered with
a thick felt of brown hairs bearing tall fan-shaped
fronds divided into numerous comb-like branches
thickly set with narrow linear leaflets on Avhich
circular clusters of spore-capsules are sparsely scat-
tered. In some respects Matonia is unlike other
ferns ; the fronds constitute a striking feature, and
the anatomy of the stem is still more distinctive.
In the form, development, and arrangement of the
sporangia (spore-capsules) — organs which from the
constancy of their characters have long been re-
cognised as the most useful basis for classification —
Matonia exhibits distinctive features.

In order to emphasise the isolated position of the

88 LINKS WITH THE PAST [ch.

genus it has recently been placed in a separate
family, the Matonineae, of which it is the sole living
representative. The restricted geographical range of
Matonia, considered in connexion witli the clearly
marked peculiarities in structure and form, leads us
to expect other evidence in support of the natural
inference that the genus is a survivor of a once
more vigorous and widely spread family. If Matonia
were a recently evolved type which has not spread
far from its original home, we should expect it to
conform more closely than it does to other ferns in
the Malay region. Even assuming for the sake of
argument that variation may occur per saltnm, and
new forms may be produced differing in more than
the finer shades of small variation from their parents,
the peculiar features of Matonia are too pronounced
and its individual characteristics too obvious to
warrant the assumption of recent production. It is,
hoAvever, from the testimony of the rocks that we
obtain confirmation of the opinion that these Malayan
species are plants on the verge of extinction. In
shales of Jurassic age exposed on the Yorkshire coast
at Gristhorpe Bay and in iron-stained rocks of the
same age between Whitby and Scarborough, well
preserved leaves have been found agreeing in the
shape of the fi-ond, as also in the form of the leaflets
and of the groups of sporangia which they bare, with
those of Matonia pectinata.

v] FERNS 89

The exposure by a stroke of the hammer, on the
fractured surface of a rock picked up on the beach
at Hayburn Wyke (a few miles south of Whitby), of
a piece of fern frond which is unmistakably closely
allied to the species described by Wallace on Mount
Ophir, establishes a link between the Jurassic and
the present era and presents a fascinating problem in
geogi^aphical distribution. These fossil Matonias are
known to students of ancient plants as species of
the genus Matonidium, a name adopted by a German
botanist for specimens apparently identical with those
from the Yorkshire coast discovered in slightly younger
rocks (Wealden) in North Germany. The same type
has been found also in sediments of Wealden age on
the Sussex coast. Other leaf-impressions agreeing
closely with those of Matonidium have been obtained
from the Yorkshire Jurassic rocks and these are
assigned to another genus Laccopteris, an extinct
member of the family Matonineae. It is not merely
in the habit of the fronds and in the shape and
venation of the leaflets that these fossil ferns resemble
the existing species, but the more important features
exhibited by the spore-capsules supply additional evi-
dence. It has already been pointed out that the stems
of Matonia are characterised by a type of structure
unknown in an identical form in any other recent fern.

A few years ago Prof. Bommer discovered frag-
ments of leaves and stems in Wealden beds a few

90 LINKS WITH THE PAST [ch.

miles from Brussels sufficiently well preserved to
reveal the details of internal organisation. Some
of these fossils were found to possess structural
features identical Avith those of the Malayan species
of Matonia. A full account of the fossil representa-
tives of the Matonia family would be out of place in
a general essay on Links with the Past, but brief
reference may be made to some of the data which
throw light on the geological history of the family.
In strata classed by geologists as Rhaetic, a phase
of earth-history between the Triassic and Jurassic
eras (see p. 42), species of Laccopteris and allied forms
have been described from several otlier countries ;
from Jurassic and Wealden strata examples of both
Laccopteris and Matonia have been found in Germany,
Portugal, Belgium, Austria, and elsewhere. From
rocks of Cretaceous age, higher in the series than
the Wealden strata, Avell preserved impressions of
a Matonidium have been discovered in JMoravia.
The Matonineae were widely distributed in Europe
during the Rhaetic and Jurassic periods, but, so far
as we know, the family did not survive in the northern
hemisphere beyond the limits of the Cretaceous
period. It is noteworthy that, in spite of the
preservation of the remains of Jurassic and Cre-
taceous floras in many extra-European regions,
notably in India, South Africa, Australia, China, and
Tonkin, no specimens have been found which can

V] FERNS 91

with confidence be assigned to the Matonineae. A
single fossil has, however, been described from Queens-
land which may be a piece of a Laccopteris frond.

There is some evidence that ferns very similar to
INIatonia existed in North America during the Meso-
zoic period. It would be in the highest degree rash
to assume that the Matonineae played no part in
the Jurassic vegetation of India, South Africa, and
other southern lands, but there can be little doubt
that the family was especially characteristic of
European floras during a portion of the Mesozoic
era. It would seem that subsequent to the Wealden
period the ancestors of Matonia dwindled in numbers
and their geographical range became much more
restricted.

The records of Tertiary rocks have hitherto added
nothing to our knowledge of the distribution of the
family subse(pient to the Cretaceous period. All
we can say is that the existing species of INIatonia
are the last survivoi's of a family which in the
Jurassic period overspread a wide area in Europe
and probably extended to the other side of the
Atlantic. Exposed to unfavourable climatic con-
ditions and possibly affected by the revolution in
the plant world consequent on the appearance of
the Flowering Plants, the Matonineae gradually
retreated beyond the equator until the two surviving
species found a last retreat in the Malayan region.

92

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P'ig. 12. Dipteris conjugata Kein. anJ, in the middle of the upper
part of the photograph, a frond of Matonia pectinata R. Brown.
Mount Ophir. (Pliotograph by Mr A. G. Tansley.)

V] FERNS 93

The fern spoken of by Dr Wallace as Dipteris
Horsfieldii (perhaps better known as DijJteris
conjugata (Fig. 12)), which grows with Matonia
jjecthiata on Mount Ophir and in the Malay region
generally, is one of seven species of a genus charac-
terised by a somewhat wider geographical range
than Matonia. Dipteris conjugata extends to the
Philippines, Samoa, Fiji, New Caledonia, New Guinea
and Central China ; its fronds, like those of Matonia,
are borne on long slender stalks attached to a
creeping stem ; they have a broad lamina divided by
a deep median sinus into two symmetrical halves and
each half is cut up into segments with a saw-like
edge. Several stout ribs spread through the lamina
from the apex of the long stalk like the open fingers
of a hand ; from these ribs smaller veins are given
off at a wide angle, and these in turn give rise to a
reticulum of finer veins forming a skeletal system
like that in the leaves of an oak and many other
flowering plants.

Numerous groups of spore-capsules are borne on
the lower surface of the broad lobed frond. The
leaves of other species of Dipteris have the same
type of structure, but in some the segmentation of
the lamina is carried further and the leaf consists of
numerous long and narrow segments with one or two
main ribs. Dipteris is represented in the flora
of Assam, and it is interesting to find that a species

94 LINKS WITH THE PAST [ch. v

recently discovered in Borneo is more closely con-
nected witli the Assam type than with those of the
IMalay region. Until a few years ago the genus
Dipteris was included in the large family Polypodi-
aceae of which nearly all our British ferns are
members, but the discovery of certain distinguishing
features in the structure of the sporangia showed
that these Eastern and Southern species form a
fairly well-defined group worthy of family rank.

In the Rhaetic plant-beds of Northern and
Central Europe, of North America, Tonkin, and
elsewhere, numerous fossil leaves have been dis-
covered which in shape, venation, and in the
manner of occurrence of the sporangia bear a close
resemblance to species of Dipteris. Ferns of this
type were abundant in the Jurassic floras of the
northern hemisphere, and it is interesting to find
impressions of Dipteris-like leaves both in the
Jurassic rocks of the Yorkshire coast as well as in
slightly newer beds of the same geological period on
the north-east coast of Sutherland.

It is impossible to say with confidence how nearly
these Rhaetic and Jurassic ferns were related to the
existing species, as our knowledge of them is less
complete than in the case of the fossil representatives
of the Matonineae, but there can be no reasonable
doubt that in Dipteris as in Matonia we have a con-
necting link between the present and a remote past.

CHAPTER VI

THE REDWOOD AND MAMMOTH TREES
OF CALIFORNIA

'Your sense is sealed, or you should hear them tell
The tale of their dim life, with all
Its compost of experience ' W. E. Henley.

Since their introduction into England about the
middle of the nineteenth century, the two Californian
species Sequoia sempervirens (the Redwood) and
Sequoia gigantea (the Mammoth tree) have become
familiar as cultivated trees. The name Sequoia,
said to be taken from Sequoiah, the inventor of the
Cherokee alphabet, was instituted in 1847, while the
name Wellingtonia, often used in horticulture though
discarded by botanists in favour of the older designa-
tion Sequoia, was proposed in 1853. Both species
are now confined to a comparatively small area in
California : their restricted geographical range, con-
sidered as an isolated fact, might be regarded as a
sign of recent origin. The records of the rocks,
however, afford ample proof that rarity in this as in

96 LINKS WITH THE PAST [ch. vi

many other instances is the precursor of extinction.
The famous groves of Mariposa and Calaveras
represent the last resting-place of giant survivors
of a race Avhich formerly held its own in Europe and
in other parts of the world.

The Redwood, Sequoia sempervirens, occupies a
narrow belt of country, rarely more than 20 or 30
miles from the coast, three hundred miles long from
Monterey in the south to the frontiers of Oregon ;
it has a stronger hold on existence than Sequoia
gigantea. In Northern California it still forms pure
forests on the sides of ravines and on the banks of
streams. The tapering trunk, rising from a broad
base to over 300 ft., gives off short horizontal
branches thickly set with narrow spirally disposed
leaves i — J inch in length arranged in two ranks
like the similar leaves of the Yew. The lower
edge of each leaf is decurrent, that is it runs a
short distance doAvn the axis of the branch instead of
terminating at the point of attachment. It is by
paying attention to such details as this as well as to
more important features, that we are able to connect
fragmentary fossil twigs with those of existing
species. The female 'flowers' have the form of
oblong cones from | to 1 inch long : each consists
of a central axis bearing crowded wedge-shaped,
woody appendages or cone-scales, which gradually
increase in breadth towards the exposed distal end

Fig. 13, Sequoia gigantea. King's Co., California.
(From Prof. D. H. Campbell)

98 LINKS WITH THE PAST [ch. vi

characterised b}' its four sloping sides and by a
median transverse groove. Several small seeds are
borne on the upper surface of the cone-scales. The
smaller and short-lived male flowers need not be
described.

The other and better known species Sequoia
glgatitea (Fig. 13) has an even more restricted range
and is confined to groves on the western slopes of
the Sierra Nevada between 3000 to 9000 ft. above
sea-level.

This tree is at once distinguished from the
Redwood by its ovate, sharply pointed and stiffer
leaves which retain their spiral disposition and
closely surround the axis of the twigs like obliquely-
set needles. The cones are of the same type as those
of Sequoia sempervirens, but are broader and may
attain a length of 3^ inches (9*5 cm.) (Fig. 14).

Reference has already been made to Sequoia
as a striking illustration of longevity. It is also
selected as an equally impressive example of a tjpe
verging on extinction, which played a prominent part
in the vegetation of both west and east during the
Cretaceous and Tertiary periods.

Scraps of branches with leaves hardly distinguish-
able from those of the existing Californian trees
are frequently met with in Tertiary and Mesozoic
sediments, and with them occasionally occur cones
too imperfectly preserved to aftbrd satisfactory

Fig. 14. Sequoia gigantea Torr. (| nat. size.)

7—2

100 LINKS WITH THE PAST [ch.

evidence of more tlian superficial agreement with
those of tlic recent species. The task of deciphering
the past history of plants, particularly of the Conifers,
is accompanied by many difficulties and insidious
temptations. It is clear from a critical examination
of many of the recorded instances of fossil Sequoias
that the generic name has been frequently used by
writers without adequate grounds. The fragmentary
specimens available to the botanical historian cannot
as a rule be subjected to microscopical investigation,
and even a partial acquaintance with the similarity
of the foliage of different types of living Conifers is
sufficient to convince the student of the need of self-
control in the identification of the fossils. It is,
how^ever, easy to point out obvious pitfalls, though
difficult to maintain a judicial attitude in the
excitement of endeavouring to interpret documents
which are too inconq^lete to be identified with
certainty. If w^e put on one side all records of
supposed fossil Sequoias not based on satisfactory
data, there remains a wealth of material testifying to
the antiquity of the surviving species.

It is by no means improbable that Conifers
closely allied to the RedAvoods and Mammoth trees
of California were represented in Jurassic floras ;
but hitherto no proof has been obtained of the
occurrence of a Sequoia among the rich material
aflbrded by the Jurassic plant-beds of Yorkshire

VI] REDWOOD AND MAMMOTH TREES 101

and by beds of tlie same age in other countries.
A small cone has recently been described from
strata near Boulogne belonging to the latest phase
of the Jurassic period, which presents a strong
resemblance in shape and size and in the form of the
cone-scales to those of the recent species. This speci-
men, though not conclusive, is the most satisfactory
indication of a Jurassic Sequoia so far discovered.
From Lower Jurassic rocks in Madagascar similar
cones have been recorded in association with foliage-
shoots like those of Sequoia gigantea, but here too
the evidence is not beyond suspicion. In plant-
bearing strata of Wealden age, such as are exposed
in the cliff near Hastings and in deposits of the same
age in North Germany, Portugal, and elsewhere,
twigs and cones have been found Avhich may be
those of trees nearly allied to the genus Sequoia.

It is, however, in the sedimentary rocks of
Cretaceous age, rather higher in the series than
those in the Hastings cliffs, and in the succeeding
Tertiary rocks, that undoubted Sequoias are met
with in abundance. At Bovey Tracey in Devonshire
there is a basin-shaped depression in the granitic rocks
of Dartmoor filled with clay, gravel and sand — the
flood-deposits of a Tertiary lake containing waifs and
strays of the vegetation on the surrounding hills.
Among the commonest plants is one to which the
late Oswald Heer gave the name Sequoia CouUsiae,

102 LINKS WITH THE PAST [cH.

and his reference of the specimens to the genus
Sequoia has been confirmed by the recent researches
of Air and Mrs Clement Reid(5o). This Tertiary
(Oligocene) species is represented by slender twigs
almost identical with those of Sequoia glgantea and
by well-preserved cone-scales and seeds (Fig. 15).

i»

A B

Fig. 15. Sequoia Couttsiae Heer. Twigs (A) and cone-scales (B)
from Bovey Tracey. ( x 3. ) (Photographs by Mr and Mrs Clement
Beid.)

Moreover, it has been possible to examine micro-
scopically the structure of the carbonised outer skin
of the leaves and to demonstrate its agreement with
that of the superficial tissue in the leaves of the
Mammoth tree. With the Bovey Tracey Sequoia

VI] REDWOOD AND MAMMOTH TREES 103

are associated fragments of Magnolia, Vitis, and
Taxodium dlstichum, the swamp Cypress of North
America, together with other types which have long
ceased to exist in Western Europe. Other British
examples of Sequoia have been described from
Tertiary beds at Bournemouth, the Isle of Wight,
Sheppey, and Antrim, but the material from these
localities is inferior in preservation and cannot be
identified with the same degree of certainty as in the
case of the Devonshire specimens. The occurrence
of twigs and cones of several species of Sequoia in
both Cretaceous and Tertiary rocks in Austria,
Germany, Italy, France, and elsewhere, shows that
the ancestors of the Californian trees were common
in the European region.

The exploration of Cretaceous and Tertiary rocks
in Arctic Europe has revealed the former existence in
Greenland, Spitzbergen, and other more or less ice-
covered lands of plants which clearly denote a mild
climate. Cones and branches of Sequoias have been
found in abundance in Lower Tertiary beds on Disco
Island off the west coast of Greenland, and similar
evidence of the northern extension of the genus has
been obtained from Spitzbergen. DrNathorst of Stock-
holm speaks of twigs of Sequoia in the Tertiary clays
of Ellesmere Land almost as perfect as herbarium
specimens. In Tertiary beds on the banks of the
Mackenzie River, in Alaska, Saghalien Island and

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Vancouver Island, and in Upper Cretaceous rocks in
the Queen Charlotte Islands, remains of Sequoia have
been discovered. One of the most remarkable in-
stances of the preservation of trees of a bygone age
is supplied by the volcanic deposits of Lower Tertiary
age exposed on the slopes of Amethyst mountain
in the Yellowstone Park district. At different levels
in the volcanic and sedimentary material, which is
piled up to a height of over 2000 ft. above the valley,
as many as fifteen forests are represented by erect
and prostrate limbs of petrified trees (Fig. G). The
microscopical examination of some of these trees
has shown that they bear a striking resemblance to
Sequoia semiiervirens. In a photograph of these
petrified forests by the U.S. Geological Survey (36,2)
one sees living Conifers side by side with the lichen-
covered and weathered trunks of the fossil species
{Sequoia tnagiufica), living and extinct being at a
distance hardly distinguishable. (Frontispiece.)

In concluding this brief survey of the fossil records
of Sequoia, reference may be made to the discovery
of petrified wood in Cretaceous rocks in South Nevada,
possessing the anatomical featnresof Sequoia (/igantea,
which shows that close to the present home of the big
trees their ancestors flourished during a period of the
earth's history too remote to be measured by human
reckoning.

The distribution of the Tertiary and Cretaceous

VI] REDWOOD AND MAMMOTH TREES 105

Sequoias would appear to have been mainly in the
northern hemisphere, extending well within the Arctic
circle. It is, however, by no means improbable that
the ancestors of Sequoia flourished far south of the
equator. Reference has been made to Jurassic fossils
from Madagascar which have been compared with the
existing species, and from LoAver Tertiary beds in
New Zealand the late Baron Ettingshausen described
some cones and twigs as Sequoia novae zeelandicae
which bear a close resemblance to the existing type.
The available evidence would seem to point to a
northern origin of the genus, though allowance must
be made for erroneous conclusions based on negative
evidence. Further research may well extend the past
distribution of Sequoia in southern lands, but the
data to hand point to the conclusion that the Cali-
fornian trees represent the survivors of a type which
flourished in the Cretaceous and Tertiary periods
over a wide area in North America and in what we
now call the Continent of Europe.

CHAPTEll VII

THE ARAUCARIA FAMILY

'And so the grandeur of the Forest-tree
Comes not by casting in a formal mould,
But from its own divine vitality.' Wordsworth,

As an additional illustration of existing cone-
bearing trees which form links with the past we may
briefly consider the genera Araucaria and Agathis,
the two members of the family Araucarieae. It is
generally agreed that the branches of the genealogical
tree of this family extended farther back into the
past than in the case of the majority of Conifers. By
some authors the surviving representatives of the
x\raucarian stock are considered to have a strong
claim to be regarded as the most primitive as well as
the oldest of cone-bearing trees, though this opinion,
like many others, is not held by botanists as a whole.
This is not the place to discuss matters of controversy,
and I shall confine myself to a general consideration
of Araucaria and Agathis from the point of view of
their present distribution and the part they played in

CH. VII] THE ARAUCARIA FAMILY 107

the vegetation of the Mesozoic and Tertiary epochs.
In 1741 a plant from Amboyna, one of the Moluccas, was
described under the name Dammara alba. For this
tree, known as the Amboyna Fine, the English botanist
Salisbury instituted the generic name Agathis, from a
Greek word (dyadic) meaning a ball of string and pro-
bably suggested by the form of the cones, which is the
designation usually adopted in botanical literature
instead of the pre-Linnean term Dammara. The best
known species of the genus is the Kauri Pine, probably
the finest forest tree in New Zealand where it still
flourishes from the North Cape to latitude 38° S.,
though the occurrence of sub-fossil trunks and pieces
of buried resin shows that the Kauri forests are gradu-
ally dwindling. The stems of this species, Agathis
australis, rise like massive grey columns to a height
of 160 ft., terminating in a succession of spreading
branches given off* in tiers from the main trunk. The
thick narrow lanceolate leaves, with several parallel
veins, reach a length of 2 to 3 inches. The female
shoots have the form of small and almost spherical
cones consisting of a central axis bearing overlapping
spiral series of broadly triangular scales (Fig. 16).
Each scale carries a single seed with a large wing
attached to one side which facilitates disposal by
wind. Other species of Agathis occur in the Malay
Archipelago, the Philippines, in Queensland, in the
New Hebrides, New Caledonia, the Fiji Islands, and

108 LINKS WITH THE PAST [ch.

VII] THE ARAUCARIA FAMILY 109

elsewhere. With the exception of the Australian
Kauri (Agathis rohusta), with leaves larger and
broader than those of the New Zealand Kauri, the
genus is essentially an island type. With the ex-
ception of some species of the southern hemisphere
genus Podocarpus, there are no Conifers with foliage
like that of Agathis. It is, however, the broad and thin
single-seeded scales and the spherical cones, in some
species six inches in length, which furnish the most
trustworthy means of identifying the genus.

The allied genus Araucaria, with the exception
of two South American species, the familiar Monkey
Puzzle, Araucaria imbricata, and a Brazilian tree,
Araucaria hrasiliana, is confined within the geo-
graphical area occupied by Agathis. The name Arau-
caria was first used by de Jussieu in 1789 for a plant
previously referred to the genus Pinus and described
as one of the most beautiful trees of Chili. This
species, A. imbricata, introduced into England in
1796, grows on the southern slopes of the Andes and,
as in the case of the Kauri forests of New Zealand,
buried stems point to a wider extension of the forests
in earlier days. The sharp and thick leaves of the
Monkey Puzzle distinguish it from all other Conifers ;
its large almost spherical seed-bearing cones, more
than half a foot in length, which may occasionally be
seen on well-grown British trees, are unlike those of
other genera. Each of the deep and narrow scales

110

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[CH.

bears a single seed embedded in the substance of the
scale and terminates distally in a narrow upturned
process. Some species of Araucaria, differing con-
siderably in the form of the leaves and in the shape
and structure of the seed-scales from the Chilian
species, are conveniently placed in a distinct sub-

Fig. 17. Araucaria excelsa. The upper part of a small tree in the
Cambridge Botanic Garden. (Much reduced.)

division of the genus Araucaria. Of this type the
Norfolk Island Pine, Araucaria cxcelsa, is the best-
known example (Fig. 17). It was introduced to Kew
by Sir Joseph Banks in 1/93, soon after its discovery
by Captain Cook, who describes the stems of the

VII] THE ARAUCARIA FAMILY 111

Norfolk Island trees as resembling basaltic columns,
and relates how on approaching the island everyone
was satisfied that the columnar objects were trees,
* except our Philosophers, who still maintained they
were basaltes.' The leaves are short, about half an
inch long, laterally compressed and slightly spreading
and sickle-shaped — sometimes shorter and broader
and overlapping — arranged in crowded spirals. The
scales of the broadly oval cones are single-seeded, but
differ from those of Arancaria imhricata in having the
seed exposed on the surface and in the greater breadth
and thinner borders of the scales. In both Araucaria
and Agathis the nature of the seed-scales constitutes
a distinguishing feature. The leaves of Arcmcarla
imhricata differ in form from those of other Conifers.
The foliage shoots of Araucaria excclsa and other
species, e.g. the very closely allied A. Cooldi of the
New Hebrides and New Caledonia, though not unlike
the branches of a Japanese Conifer {Cryptomeria
japouica), often cultivated in England, afford fairly
trustworthy characters for identification purposes.

The minute structure of the wood of both Araucaria
and Agathis constitutes an important distinguishing
feature and enables us to recognise on microscopical
examination even a fragment of wood of either of
these genera. The small elongated cells or water-
conducting elements of the wood of the Araucarieae
are characterised by one or two, and occasionally as

112 LINKS WITH THE PAST [ch.

many as three or four, contiguous rows of pits on their
radial walls, and these appear in surface view as
flattened circles or polygonal areas.

These details have been mentioned in order to show
that Araucaria and Agathis are sufficiently distinct
in many respects from other Conifers to render their
identification in a fossil state comparatively easy, at
least much easier than the recognition of the majority
of the members of the Coniferae. It would be going
too far to state definitely that Araucarieae, as defined
by reference to existing species, existed during the
Palaeozoic period ; on the other hand it would seem
in a high degree probable that the vegetation of the
Coal age and of the succeeding Permian period in-
cluded trees in which certain Araucarian characters
were clearly foreshadowed. The name Araucarioxylon
was formerly applied to petrified wood, obtained from
Palaeozoic as well as from later formations, which
agrees anatomically with that of Araucaria and Agathis.
It has been shown in recent years that much of the
Palaeozoic wood of this type of structure belongs
to the extinct genus Cordaites, a tree which played
a prominent part in the earlier floras. Cordaites
affords a good example of a generalised type : in
its wood-structure it resembles very closely the
existing Araucarieae ; its long strap-like leaves are
not unlike those of some species of Agathis ; its
male flowers have often been compared with those

VII] THE ARAUCARIA FAMILY 113

of the Maiden Hair tree, Ginlcgo hiloha, and certain
anatomical features form connecting links between
this Palaeozoic genus and the Cycads.

It is noteworthy that in another Palaeozoic genus,
Walchia, the leaf-bearing branches are identical in ap-
pearance with those of the Norfolk Island Pine (Fig. 17)
and some other species of Araucaria. Unfortunately
our knowledge of the reproductive organs of Walchia
is insufficient to warrant any definite statement as to
the degree of consanguinity between this Permian and
Upper Carboniferous plant and the Araucarieae ; it
is probable that in Walchia we have a type not far
removed from the line of evolution which led to
Araucaria. Petrified wood, identified as that of
Walchia, and exhibiting the Araucarian type of struc-
ture, has been recorded from Permian rocks of the
Vosges. Other instances might be quoted in support
of the view that the Palaeozoic floras included a few
plants with which the surviving Araucarieae may
fairly claim relationship. Professor Zeiller of Paris
has recently described some fossil shoots from Palaeo-
zoic rocks in India under the name xiraucarUcs
Oldhami on the ground of the similarity of the leaves
to those of Araucaria imhricata. Similarly, from
Triassic rocks several fossils have been described as
closely allied to Araucaria, in some cases because of
anatomical resemblances and in others on the less
satisfactory evidence furnished by a similarity in the
s. 8

114 LINKS WITH THE PAST [ch.

foliage slioots. Professor Jeffrey of Harvard has re-
cently given an account of a new type of stem
(Woodworthia) from the petrified Triassic forest of
Arizona possessing some Araucarian characters,
though differing from existing species of Araucaria
in certain structural features, a combination of
characters regarded by this Author as an indication
of relationship with the family of Conifers, which
includes the Pines, Firs, Larches and other well-known
northern genera.

It is, however, from the records of Jurassic rocks
that we obtain the most satisfactory information as to
the great antiquity and the very wide geographical
range of the ancestors of the recent genus. The plant-
beds of the Yorkshire coast afford clear evidence of
the occurrence of Araucarian trees in the woodlands
of the Jurassic period. Petrified wood has been found
at Whitby, associated with jet, showing the minute
structural characteristics of the surviving species of
Araucarieae, and it is not improbable that some at
least of the Whitby jet has been formed from the wood
of Araucarian plants. The carbonised remains of
leafy shoots preserved in the Jurassic shales near
Scarborough and on other parts of the Yorkshire
coast include twigs hardly distinguishable from those
of Araucaria excelsa, though the resemblance of
external form alone, especially in the case of foliage
shoots, does not amount to proof of generic identity.

VII] THE AR AUG ARIA FAMILY 115

We have, however, the much more trustworthy evi-
dence of cones and seed-bearing scales in which the
characteristic features of living species are clearly
shown. Seed-bearing scales almost identical with those
of Arancaria excel sa and other recent species have
long been known from the Jurassic rocks of Yorkshire.

From other parts of England where samples of
Jurassic floras are preserved, as at Stonesfield in
Oxfordshire, in Northamptonshire and elsewhere,
equally striking examples of undoubted Araucarias
have been found.

Fig. 18 represents part of a large cone described
in 1866 by Mr Carruthers from Jurassic rocks at
Bruton in Somersetshire : this specimen, now in the
British INIuseum, consists of one side of a spherical
cone about 5 inches long and 5 inches broad ; in size,
as in the form of the seed-scales, it shows a striking
likeness to the cones of the Australian species
Araucaina BidwilliL the Bunya Bunya of Queens-
land. Other equally convincing examples of Jurassic
Araucarian cones and seeds may be seen in the
museums of York and Northampton. On the north-
east coast of Sutherland there is a narrow strip of
Jurassic beds forming a low platform between the
granitic and Old Red Sandstone hills and the sea.
From these rocks Hugh Miller described several
fossil plants in his Testimony of the Bocls, and an
examination of a large collection obtained from this

8—2

116

LINKS WITH THP] PAST

[CH.

Fig. 18. Araucarites ^jylKwrocarpus Carr. From Jurassic rocks at
Bruton, Somersetshire. (British Museum, f nat. size.)

VII] THE ARAUCARIA FAMILY 117

district by the late Dr INIarciis Guiin shows that
Miller was justified in speaking of Araucaria as a
member of this northern flora.

There is abundant evidence pointing to the exist-
ence in Britain during the Jurassic period, and in
the early days of the Cretaceous epoch, of Araucarian
trees which differed but slightly from the modern
species confined to the southern hemisphere. In
several localities in France, Germany, and other parts
of the continent, Araucarian fossils have been recog-
nised in Jurassic rocks. It is almost certain that
some foliage shoots and imperfectly preserved cones
described by Dr Nathorst from Upper Jurassic rocks
in Spitzbergen were borne by a species of Araucaria.
Cone-scales very similar to those from Yorkshire have
been discovered in Wealden beds in Cape Colony, and
Araucarian wood of Jurassic and Cretaceous age has
been found in Madagascar. From Jurassic strata in
India and Victoria (Australia), as well as from Upper
Jurassic and Lower Cretaceous rocks in Virginia and
elsewhere in the eastern United States, Avell preserved
Araucarian fossils are recorded. In a collection of
Jurassic plants, obtained a few years ago by the
members of a Swedish Antarctic Expedition in
Graham's Land, Dr Nathorst has recognised some
cone-scales of Araucaria, which demonstrate a former
extension of the family beyond the southern limits of
South America.

118 LINKS WITH THE PAST [ch.

It is interesting to find that when we ascend higher
in the geological series and pass beyond the Wealden
strata to the Middle and Upper sub-divisions of the
Cretaceous period, evidence of the Avide geogra^jhical
distribution of the Araucarieae is still abundant.
Araucarian wood has been obtained in rocks classed
as Upper Cretaceous in Egypt, in East Africa, in
Dakota, and elscAvhere. In the sedimentary rocks of
the Tertiary period undoubted examples of Araucaria
are less common, though there can be no doubt that
the genus was much more widely spread then than
it is at the present day. The Avell-known Tertiary
plant-beds of Bournemouth have afforded specimens
of foliage shoots which have been described as a
species of Araucaria, though in the absence of well-
preserved cones or petrified Avood we must admit
that the data are inconclusive. It is, however,
legitimate to regard the striking similarity of the
Bournemouth twigs to those of Araucaria excelsa
and A . CooJcii as constituting a fairly strong case in
favour of the persistence of Araucaria in Western
Europe up to the earlier stage of the Tertiary period.
Araucarian wood of Tertiary age is recorded from
India, while branches with broad leaves like those
of Araucaria imhricata have been found in Seymour
Island and the ^lagellan Straits, and specimens
of Tertiary wood are described from Patagonia.
At the other end of the world. Tertiary rocks on the

VII] THE ARAUCARIA FAMILY 119

west coast of Greenland have yielded fragments which
may be referred with some hesitation to the genus
Araucaria.

A few words must be added in regard to the recent
discovery by Professor Jeffrey and Dr Hollick of some
very interesting Cretaceous specimens in New Jersey
of well-preserved cone-scales and foliage shoots of
extinct plants closely related to the existing species
of Agathis (51). The American fossils are particularly
valuable because their preservation admits of micro-
scopical examination of the tissues. In Cretaceous
rocks of Staten Island and in other localities on the
eastern border of the northern United States, kite-
shaped seed-bearing scales almost identical in form
with those of recent species of Agathis are fairly
common fossils. Similar specimens have long been
known from Tertiary rocks in western Greenland.
In the case of some of the American examples each
scale bore three seeds instead of a single seed in
living species: on account of this difference Prof.
Jeffrey and Dr Hollick have adopted a distinct
generic name, Protodmnmara.

The foregoing sketch is necessarily far from com-
plete, but it may serve as aii illustration of the light
which is thrown on the past history of recent plants
by the investigation of the relics of ancient floras.
The family Araucarieae now represented by a small
number of species which, with the exception of the

120 LINKS WITH THE PAST [ch. vii

Andian and Brazilian Araucarias, are restricted to a
small region in the southern hemisphere, was one of
the most widely spread sections of the seed-bearing
plants during the Mesozoic era. Ancestors of Arau-
caria must have been common trees in the European
vegetation in Jurassic and Lower Cretaceous periods,
and even as late as the Tertiary period there is evidence
that representatives of the family still lingered in
the north. One conclusion which seems almost un-
avoidable is that the species of Araucaria and Agathis
that survive, in some cases only in one or two small
islands in the South Pacific, have in the course of
successive ages wandered from the other end of the
world. Their migrations can be partially traced by
the fragments embedded in Jurassic and later sedi-
ments, but we can only speculate as to the causes
which have contributed to the changes in the fortunes
of the family ; how much influence may have been
exerted by changes in physical conditions in the
environment, and to what extent the production of
more successful types may have been the dominant
cause of the decline, it is impossible to say. One
thing at least is certain, that few existing plants are
better entitled to veneration as survivals from the
past than are the living species of Araucaria.

CHAPTER VIII

THE MAIDEN HAIR TREE

' ...the trees
That whisper round a temple become soon
Dear as the temple's self.' Keats.

The Maiden Hair tree of China and Japan, which
Avas introduced into Europe early in the eighteenth
century, has now become fairly well known. Though
hardy in England, it requires warmer summers for
full development and regular flowering. To botan-
ists this Eastern tree is of peculiar interest, partly
because of the isolated position it occupies in the
plant-kingdom and partly by reason of its great
antiquity. There is probably no other existing tree
which has so strong a claim to be styled a 'living
fossil,' to use a term applied by Darwin to survivals
from the past. In 1/12 the traveller Kaempfer
proposed for this plant the generic name Ginkgo,
and Linnaeus adopted this designation, adding the
specific name biloha to denote the bisection of
the wedge-shaped lamina of the leaf into two

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[CH.

divergent segments. In 1777 the English botanist
Sir J. E. Smith expressed his disapproval of what

Fig. 19. Ginkgo biloha Linn. (Slightly reduced.)

he called the uncouth name Ginkgo by substituting
for Ginkgo biloha the title Salisburia adiantifoliaj

VIII] THE MAIDEN HAIR TREE 123

but as it is customary to retain names adopted or
proposed by Linnaeus, the founder of the binominal
system of nomenclature, the correct botanical desig-
nation of the maiden hair tree is Ghikgo hiloha.
Mere personal preference such as that of Sir J. E.
Smith for Salisburia is not an adequate reason for
rejecting an older name.

In its pyramidal habit Ginkgo agrees generally
with the larch and other Conifers. Like the larch
and cedar it possesses two kinds of foliage shoots,
the more rapidly growing long shoots with scattered
leaves and the much shorter dwarf-shoots which
elongate slightly each year and bear several leaves
crowded round their apex. The leaves (Fig. 19),
which are shed each year, are similar in the cuneate
form of the lamina and in the fan-like distribution
of the forked veins, to the large leaflets of some
species of maiden hair ferns : the thin lamina carried
by a slender leaf-stalk is usually about 3 inches
across, though in exceptional cases it may reach a
breadth of 8 inches. The lamina is usually divided
by a deep V-shaped sinus into two equal halves ;
it may be entire with an irregularly crenulate margin,
or, on seedlings and vigorous long shoots, the lamina
may be cut into several wedge-shaped segments.

The male and female flowers are borne on separate
trees ; the male consists of a central axis giving off
slender branches, each of which ends in a small

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terminal knot and two elliptical capsules in which
the pollen is produced. The female flowers have
a stouter axis which normally produces two seeds
at the apex. The seed is encased in a green fleshy
substance and, as in the fruit of a cherry or plum,
the kernel is protected by a hard w^oody shell. In
the form of the leaves and in the structure of the
flowers Ginkgo presents features which clearly dis-
tinguish it from the Conifers, the class in w^hich,
until recently, it w^as included. In 1896 the Japanese
botanist Hirase made the important discovery that
the male reproductive cells of Ginkgo are large
motile bodies provided Avith a spirally coiled band
of minute cilia — delicate hairs which by their
rapid lashing-movement propel the cell through
water. In all Flow ering Plants and in Conifers the
male reproductive cells have no independent means
of locomotion ; they are carried to the female cell
by the formation of a slender tube — the pollen-tube —
produced by the pollen-grain. In the Ferns, Lyco-
pods and Horsetails — in fact in all members of
the Pteridophyta — as also in the Mosses and Liver-
worts as well as in many of the still lower plants, the
male cells swim to the egg by the lashing of cilia
like those on the male cells of Ginkgo. This difference
in regard to the nature of the male cells was con-
sidered to be a fundamental distinction between the
higher seed-bearing plants and all other groups of

VIII] THE MAIDEN HAIR TREE 125

the vegetable kingdom. It was, therefore, with no
ordinary interest that Hirase's discovery was received,
as it broke down a distinction between the two great
divisions of the plant- world which had been generally
accepted as fundamental ; though it is only fair to
say that the German botanist Hofmeister, a man of
exceptional originality and power of grasping the
essential, foresaw the possibility that this arbitrary
barrier would eventually be removed. The Ferns
and other plants in which the male cells are motile,
represent earlier stages in the progress of plant
development, when the presence of water was essen-
tial for the act of fertilisation, a relic of earlier days
when the whole plant-body was fitted for a life in
water. As higher types were produced, the plant-
machinery became less dependent on an aqueous
habitat, and the loss of organs of locomotion in the
male cells is an instance of the kind of change
accompanying the gradual adaptation to life on
land. The idea of the gradual emancipation of plants
from a watery environment is expressed in a some-
what extreme form by the author of a book entitled
The Lessons of Evolution (52), who states that the
ocean is the mother of plant-life and that plants
formed the army which conquered the land. In
Ginkgo we have a type which, though similar in
most respects to the (.Conifers, possesses in its motile
reproductive cells a persistent inheritance from the

126 LINKS WITH THE PAST [cH.

past. The recognition of this special feature afforded
a sound reason, especially when other peculiarities are
considered, for removing Ginkgo from the Conifers
and instituting a new class-name, Ginkgoales.

Ginkgo is a generalised type, linked by different
characters both with living members of the two classes
of naked-seeded plants and with certain existing
Palaeozoic genera. It is a survivor of a race which
has narrowly escaped extinction ; the last of a long
line that has outlived its family and offers by its per-
sistence an impressive instance of the past in the
present. Though Mrs Bishop in her Untrodden
Patlis in Japan speaks of forests of IMaiden Hair
trees apparently in a wild state, it is generally
believed that they were cultivated specimens.
Mr Henry who has an exceptionally wide knowledge
of Cliinese vegetation tells us that 'all scientific
travellers in Japan and the leading Japanese botanists
and foresters deny its being indigenous in any part of
Japan ; and botanical collectors have not observed it
truly wild in China.' JNIoreover, Mr E. H. Wilson,
after traversing the whole of the district where
Ginkgo was supposed to occur in a wild state, says
that he found only cultivated trees. There is no reason
to doubt that China is the last stronghold of this
ancient type which in an earlier period of the earth's
history overspread the world.

A brief summary of the past history of Ginkgo

VIII] THE MAIDEN HAIR TREE 127

and of the Ginkgoales supplies overwhelming testi-
mony to the tenacity of life with which the INIaiden
Hair tree has persisted through the ages.

It was pointed out in the account of the past
history of Araucaria that the records obtained from
Palaeozoic rocks, while affording evidence of the
existence of Carboniferous and Permian genera un-
doubtedly allied to the living species, do not enable
us to speak with certainty as to the precise degree of
affinity. Similarly, Palaeozoic leaves have been de-
scribed as representatives of the class of which Ginkgo
is the sole survivor, but the evidence on which this
relationship is assumed is by no means conclusive.

The generic name Psygmophyllum has been applied
to some impressions of Ginkgo-like leaves discovered
in the Upper Devonian rocks of Bear Island, a small
remnant of land in the Arctic circle, which has fur-
nished valuable information as to the composition of
one of the oldest floras of which satisfactory remains
have been found. Other examples of these lobed,
wedge-shaped leaves are recorded fi'om Carbonifer-
ous rocks in Germany, France, and elsewhere ; from
Permian strata in the east of Russia and from Palaeo-
zoic beds in Cape Colony and Kashmir. A relationship
between Psygmophyllum and Ginkgo is, however, by
no means established and rests solely on a resemblance
in the form of the leaves. The close correspondence in
form and venation between some leaves from Permian

128 LINKS WITH THE PAST [ch.

rocks in the Ural mountains and from Lower Permian
beds in France, and those of the recent species, is
considered by some authors sufficiently striking to
justify the reference of these fossils to tlie genus
Ginkgo. Similar leaves of Permian age, which may
also be related to the existing species, have been
described under the name Ginkgophyllum. Other
specimens of Palaeozoic age from North America
and elsewhere have been assigned to the Ginkgoales ;
but in none of these cases, despite the resemblance
in leaf-form, is there sufficiently convincing evidence
of close relationship to warrant a definite assertion
that the plants in question were members of the
group of which Ginkgo alone remains.

It is, however, an undoubted fact that the INIaiden
Hair tree is connected by a long line of ancestors
with the earliest phase of the Mesozoic era. From
many parts of the world large collections of fossil
plants have been obtained from strata referred to
the Rhaetic period, or to the upper division of the
Triassic system. A comparison of floras from these
geological horizons in different parts of the world
points to a vegetation extending from Australia,
Cape Colony, and South America, to Tonkin, the south
of Sweden and North America, which Avas character-
ised by a greater uniformity than is shown by widely
separated floras at the present day. One of the com-
monest genera in Rhaetic floras is that known as

VIII] THE MAIDEN HAIR TREE 129

Baiera ; this name is applied to wedge-shaped leaves
with a slender stalk similar in shape and venation to
those of- Ginkgo, but differing in the greater number
and smaller breadth of the segments. Between the
deeply dissected leaf of a typical Baiera with its
narrow linear lobes and the entire or broadly lobed
leaf of a Ginkgo there are many connecting links, and
to some specimens either name might be applied with
equal fitness. Examples of Baiera leaves, in some
cases associated with fragments of reproductive organs,
are recorded from Rhaetic rocks of France, the south
of Sweden, Tonkin, Chili, the Argentine, Xorth America,
South Africa, and from other regions. There is abun-
dant evidence pointing to the almost world-wide
distribution of the Ginkgoales, as represented more
especially by Baiera, in the older :\Iesozoic floras. In
the later Jurassic rocks of Yorkshire true Ginkgo
leaves as well as those of the Baiera type are fairly
common ; with the leaves have been found pieces
of male and female flowers. Ginkgo and Baiera
have been described from Jurassic rocks of Germany,
France, Russia, Bornholm, and elsewhere in Europe ;
they occur abundantly in Middle Jurassic rocks in
northern Siberia, and are represented in the Juras-
sic floras of Franz Josef Land, the East Coast of
Greenland, and Spitzbergen (Fig. 20). The abund-
ance of Ginkgo and Baiera leaves associated with
male flowers and seeds discovered in Jurassic rocks,

S. a

Fig. 20. Fossil Ginkgo leaves. (| nat. size.)

A. Tertiary, Island of IMull.

B. Wealden, North Germany (after Schenk).

C. Jurassic, Jajian (after Yokoyama).

D. Jurassic, Australia (after Stirling).

E. Jurassic, Siberia (after Heer).

F. Jurassic, Turkestan.

G. Lower Cretaceous, Greenland (after Heer).
H. Jurassic, California (after Fontaine).

I. Jurassic, Yorkshire.

J. Jurassic, N.E. Scotland (after Stopes).

K. Wealden, Franz Josef Land (after Nathorst).

L. Rhaetic, South Africa.

M. Jurassic, Spitzbergen (after Heer).

CH. VIII] THE MAIDEN HAIR TREE 131

approximately of the same geological age as those on
the Yorkshire coast, in East Siberia and in the Amur
district, has led to the suggestion that this region
may have been a centre where the Ginkgoales reached
their maximum development in the Mesozoic period.

It should be added that other genera of Jurassic
and Rhaetic fossils in addition to Ginkgo and Baiera
have been referred to the Ginkgoales, though evidence
of such affinity is not convincing. There is, however,
good reason to believe that this Avidespread group
was represented by several genera in the older Meso-
zoic floras.

The occurrence of the Ginkgoales in Jurassic rocks
in King Charles Land and in the Xew Siberian Islands
(lat. 78° and 75° X.), in Central China, Japan,
Turkestan, California, Oregon, South Africa, Australia,
and Graham's Land demonstrates the cosmopolitan
nature of the group. During the later part of the
Jurassic period and in the Wealden floras both Baiera
and Ginkgo were abundant ; leaves are recorded from
Jurassic strata in the north-east of Scotland, from
Lower Cretaceous or Wealden rocks in North Germany,
Portugal, Vancouver Island, Wyoming, and Greenland.

During the Tertiary period, or probably in the
earlier days of that era. Ginkgo flourished in North
America, in Alaska and in the jNIackenzie River district,
Greenland, Saghalien Island, and in several European
regions. In Chapter III reference was made to the

9-2

132 LINKS WITH THE PAST [ch.

volcanic activity which characterised the north-west
European area in the early Tertiary period and resulted
in the formation of the thick sheets of basalt on the
north-east coast of Ireland and in the Inner Hebrides.
There were occasional pauses in the volcanic activity,
during which vegetation established itself on the
wreath ered surface of the lava, and left traces of its
existence in the leaves and twigs preserved in the
sedimentary material enclosed between successive
lava-floras. xVt Ardtun Head in the Isle of Mull
beautifully preserved leaves of Ginkgo, 2 — 4 inches
in breadth, with the median sinus and the venation
characteristic of the leaves of the existing plant, have
been discovered in a bed of clay which marks the site
of a lake in a depression on the lava-plateau. The
resemblance of these Tertiary leaves fi-om Mull to
those of the surviving Maiden Hair tree is so close as
to suggest specific identity. Mr Starkie Gardner and
Baron Ettingshausen have described some seeds from
the London clay (Lower Tertiary) in the Isleof Sheppey
as those of Ginkgo, but this identification rests on
data too insufficient to be accepted without hesitation.
The recent cultivation of Ginkgo hiloha in Britain
may therefore be spoken of as the re-introduction of
a plant which in the earlier part or in the middle of
the Tertiary period flourished in the west of Scotland,
and was abundant in England in the earlier Jurassic
period. It is impossible to say with any confidence
where the Ginkgoales first made their appearance.

VIII] THE MAIDEN HAIR TREE 133

whether in the far north or in the south, nor are we
able to explain the gradual decline of so venerable
and vigorous a race.

As we search among the fragmentary herbaria
scattered through the sedimentar}^ rocks in that com-
paratively small portion of the earth's crust which is
accessible to investigation, we discover evidence of
a shifting of the balance of power among diiFerent
classes of plants in the course of our survey of suc-
cessive floras. Plants now insignificant and few in
number are found to be descendants of a long line of
ancestors stretching back to a remote antiquity when
they formed the dominant class. Others which flour-
ished in a former period no longer survive, either
themselves or in direct descendants. ' The extinction
of species has been involved in the most gratuitous
mystery.' We can only speculate vaguely as to the
cause of success or failure. Certain types were better
armed for the struggle for life, and produced de-
scendants able to hold their own and to perpetuate
the race through the ages in an unbroken line.
Others had a shorter life and fell out of the ranks of
the advancing and ever changing army. To quote
Darwin's words : ' We need not marvel at extinction ;
if we must marvel, let it be at our own presumption
in imagining for a moment that we understand the
many complex contingencies on which the existence
of each species depends.'

BIBLIOGRAPHY

Many of the books and papers dealing with subjects touched
upon in this vohinie are not inchided in the following- list. For
reference to a more complete bibliography the reader should
consult more technical treatises.

1. Holmes, T. Rice. Ancient Britain and the invasions of

JuHus Caesar. Oxford, 1907.

2. Mitchell, A. The Past in the Present; what is Civilisation ?

Edinburgh, 1880.

3. Wkismaxn, a. Essays upon Heredity and Kindred Bio-

logical Problems, (i. The Duration of Life.) Vol. i.
Edited by E. B. Poulton, S. Schonland, and A. E.
Shipley. (Second Edition.) Oxford, 1891.

4. The Historie of the World, commonly called the Xaturall

Historic of the C. Plinius Secundus. Translated into
English by Philemon Holland. London, 1634.

5. Hooker, J. D. On Three Oaks of Palestine. Trans.

Linnnin Society, Vol. xxiii. p. 381. 1862.

6. HoLTERMANN, Carl. Dcr Eiufluss des Klimas auf den Ban

der Pflanzengewebe. Leipzig, 1907.

7. Atkinson, A. Notes on an Ancient Boat found at Brigg.

Archaeologia, Vol. l. p. 361. 1887.

8. Huxley, T. H. Man's Place in Nature and other Anthropo-

logical Essays. Collected Essays, Vol. vii. (On the
methods and results of Ethnology.) London, 1901.

9. Lewis, F. J. The sequence of Plant Remains in the British

Peat Mosses. Science Progress, No. 0. October, 1907.

BIBLIOGRAPHY 135

10. Strahan, a. On submerged Land-surfaces at Barry,

Glamorganshire. With notes on the Fauna and Flora
by Clement Reid ; etc. Quart. Journ. Geological
Society^ Vol. Lir. p. 474. 1896.

11. The Life axd Letters of Charles Darwin. Edited by

Francis Darwin. 3 Vols. London, 1887.

12. More Letters of Charles Darwin. Edited by Francis

Darmn and A. C. Seward. 2 Vols. London, 1903.

13. Ward, Lester F. The Course of Biologic Evolution.

Anniversary Address of the President of the Biological
Society. Washington, 1890.

14. Marshall, W. Anacharis alsinash^um, a new water weed.

(Reprinted from the Cambridge Independent Press.)
London, 1852.

/ Bailey, C. Notes on the structure, the occurrence in Lanca-
shire, and the source of origin, of Naias gramineiis
Delile, var. Delilei magnus. Journal of Botany.^

] Vol. xxn. p. 305. 1884.

Weiss, F. H. and H. Murray. On the occurrence and dis-
tribution of some alien aquatic plants in the Reddish
Canal. Mem. Prvc. Manchester Lit. and Pliil. Society^
Vol. Liii. Pt. n. 1909.

16. Bennett, A. The Halifax Potamogeton. Naturalist,

No. 621. October, 1908.

17. Hooker, J. D. Outlines of the Distribution of Arctic

Plants. Trans. Linn. Soc. Vol. xxiii. p. 251. 1862.

18. Engler, a. Plants of the Northern Temperate Zone in

their transition to the High Mountains of Tropical
Africa. Annals of Botany, Vol. xviii. p. 523. 1904.

19. Darwin, C. The Origin of Species. London, 1900.

20. Ridley, H. N. On the dispersal of seeds by \d\\d. Annals

of Botany, Vol. xix. p. 351. 1905.

21. Hooker, J. D. On the Cedars of Lebanon, Taunus, Algeria,

and India. The Natural History Review, 1862, p. 11.

15

136 BIBLIOGRAPHY

22. Forbes, E. On the connection between the distribution

of the existing Fauna and Flora of the British Isles,
and the geological changes which have affected their
area.... Memoirs, Geological Surrey, Vol. i. p. 336.
1846.

23. Prakger, R. L. The Wild Flowers of the West of Ireland

and their history. Journ. R. Hort. Soc. Vol. xxxvi.
p. 299. 1910.

24. Ernst, A. The New Flora of the Volcanic Island of

Krakatau. Translated by A. C. Seward. Cambridge,
1908.

25. Praeger, R. L. a Tourist's Flora of the AVest of Ireland.

Dublin, 1909.

IRexdle, a. B. SisyrincJiium californicum Dryand.
Journal of Botany, Vol xxxiv. p. 494. 1896.
Marshall, E. S. Sisyrinchiiim calif or nicntn in Ireland.
Ihid. p. 366.
/'Reid, Clement. The Origin of the British Flora. London,

1899.
Reid, Clement and Eleanor M. On the Pre-glacial
Flora of Britain Journ. Linn. Soc. Vol. xxviii. p. 206.
1908.

28. Lankester, Sir Edwin Ray. Mature and Man. The

Romanes Lecture. Oxford, 1905.

29. Huxley, T. H. On a Piece of Chalk. Collected Essays,

Vol. viiL London, 1896.

30. Jukes-Browne, A. J. The Building of the British Isles.

Lond(m, 1911.

31. Ray, J. Three Physico-Tlieological Discourses, etc. (2nd

Edition.) London, 1693.

32. Woodward, J. An Essay toward a Natural History of

the Earth. London, 1695.

33. Sollas, W. J. The Age of the Earth, and other geological

studies. London, 1905.

26

27

36

BIBLIOGRAPHY 137

34. Ward, L. F. Status of the Mesozoic Floras of the United

States. Monograph 48, U. S. Geol. Sure. 1905.

35. Arber, E. a. Newell. Ciqyressinoxylon Ilookeri sp. nov.,

a large silicified tree from Tasmania. Geological Maga-
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/ 1. Holmes, W. H. Fossil Forests of the Volcanic Tertiary
I Formations of the Yellowstone National Park. Ann.
Rep. Geol. and Geogr. Surv. (U.S.A.), 1878, Pt. n. p. 47.
IvNowLTOiSr, F. H. Fossil Flora of the Yellowstone
National Park. Monograph 32, U. S. Geol. Survey^
Pt. n. 1899.

37. l)ARWii\, C. Journal of Researches into the Natural History

and Geology of the countries visited during the voyage
round the world of H.M.S. 'Beagle.' London, 1902.

38. DuFFERiN, Lord. Letters from High Latitudes. London.

N.D.

39. Amundsen, R. The North-West Passage. 2 Vols. London,.

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40. MacDougal, D. T. Botanical Explorations in the South-

west. Jour a. New York Botanical Garden, Vol. v.

p. 89. 1904.
I'Goeppert, H. R. and A. Menge. Die Flora des Bernsteins.
^j I Danzig, 1883.

jCoNWENTZ, H. Monographic der baltischen Bernstein-
l bilume. Danzig, 1890.

42. HovELACQUE, M. Sur la Nature vegetale de VAachenosaurus

multidens. Bull. Soc. Beige de Geol. etc.. Tome iv.
p. 59. 1890.

43. Oliver, F. W. and D. H. Scott. On the structure of the

Palaeozoic seed Lagenostoma Lomaxi. Phil. Trans.
R. Soc. Vol. cxcvii. p. 193. 1904.

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p. L

138 BIBLIOGRAPHY

45. 8MIT1I, Geoffrey. A Natunilist in Tasmania. Oxford,

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46. Campbell, 1). H. On the Distribution of the Hepaticae,

and its significance. New Phytologist^ Vol. vi. p. 203.
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Osmundaceae. Phil. Trans. R. Soc. Edinhitrg/i, Vols.
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48. Seward, A. C. Fossil Plants. 2 Vols. Cambridge, 1898-

1910.

49. Wallace, A. R. The Malay Archipelago. London, 1886. .

50. Reid, C. and Eleanor M. The Lignite of Bovey Tracey.

Phil. Trans. Royal Soc. London, Vol. 201, p. 161. 1910.

51. Hollick, a. and E. C. Jeffrey. Studies of Cretaceous

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■52. HuTTON, F. W. The Lessons of Evolution. London, 1902.

INDEX

Aachenosaurus multidens, 68

Agathis australis, 107

A. Moorei, 108

A. robusta, 108, 109

Amber, 65, 66

Amethyst Mountain, 59, 60, 104

Amundsen, E., 62

Aiiacharis alsuiastrum, 20

Angiosperms, histoiy of, 16, 53,

69, 70
Annual rings, 5-9
Antarctic fossil plants, 70, 117
Araucaria Bidivillii, 115
A. hrasiliana, 109
A. Cookii, 111, 118
A. excelsa, 110, 111, lU, 115,

118
A. imbricata, 109, 111, 113, 118
Araucarieae, 106-120
Araucarioxylon, 112
Araucarites Oldhami, 113
A. sphaerocarpus, 116
Arbutus Unedo, 31-33, 36
Archaean rocks, 43
Arctic plants, 22, 23, 30, 69, 127
Arctic-Alpine plants, 22, 23
Arizona, fossil forests of, 59
Artocarpus, 28, 29

Baiera, 129, 131
Banks, Sir Joseph, 110
Barry, forest beds at, 13

Bennett, A. , 21

Bidens trqHirtita, 46, 47

Bishop, Mrs, 126

Bommer, C, 73, 82, 89

Bovey Tracev, fossil plants from,

loi-103
Bower, Prof., 73
Bracken Fern, 75, 77, 83, 87'
Brandon, flint-knappers of, 3
Brigg, dug-out boat from, 10, 11
British flora, 19-38

Caltha palustris, 47
Campbell, Prof. D. H., 79
Candolle, A. P. de, 7, 33
Canton, W., 34
Carboniferous plants, 66-68, 72-

75, 127
Carruthers, Dr W., 115
Cedars, 27
Cheddar Pink, 24
C inn a mo mum prototypum, 65, 66
Climate, fossil plants and, 68, 69
Coal lage, plants of the, 19, 66,

67
Connemara, 30, 31
Cook, Capt., Ill
Coral polyps compared with plants,

8
Cordaites, 112
Cornwall, Pyrenean Heaths in,

31

140

INDEX

Cretaceous plants, 16, 17, 53, 82,

117
Cromer Forest bed, 48
Cryptomeria japonica, 111
Cycads, 11, 72-74

Daboecia polifolia, 30

Dacrvdium, 85

Dakota Ki^oup, flora of, 17

Dammara alba, 107

Darwin, C, 16, 24, 25, 33, 39, 40,

61, 133
Devonshire, Pyrenean Heaths in,

31
Dianthus caesius, 24
Dipteris, 77, 92-94
I), conjugata, 92, 93

D. Horsneldii, 86, 93

Disco Island, Fossil plants from,

28, 69, 82, 103
Discontinuous distribution, 26
Dispersal of plants, rate of, 25, 26
Distribution of plants, 15-38
Drift-wood, 61-63
Dry as octopetala, 22
Dufferin, Lord, 61

Elodea canadensis, 20, 21
Engler, Prof. , 23
Erica ci liar is, 31

E. Mackaii, 31

E. mediterranea, 30, 31

E. vagans, 31

EriocauJon septangnlare, 35-38

Ettingshausen, Baron, 105, 132

Ferns, 71-94

Flowering plants, see Angio-

sperms
Forbes, E., 31-34,37
Fossil plants, as thermometers,

68; preservation of, 56-70

Gardner, J. S., 132

Geogi'aphical distribution of
plants, 15-38

Geological evolution of Britain,
29

Geological record, 39-55

Geological table, 42, 43

Geological time, 2, 3, 49

Ginkqo biloba, 113, 120-133

Ginkgoales, 18, 120-133

Ginkgophyllum, 128

Glacial period, effect on vege-
tation of, 29-32, 45, 47

Gladiolus illi/riciis, 31

Gleichenia, 81-83

Graham's Land, 70, 117

Gunn, Dr Marcns, 117

Gwynue-Vaughan, Prof., 80

Gymnosperms, 17, 18

Habenaria intacta, 37

Halifax, plants from canal near,

21
Heer, 0.,33, 82, 101
Henry, A., 126
Hirase, Prof., 124, 125
Hofmeister, W. F. B., 125
Hollick, A., 119
Holmes, T. Kice, 2
Hooker, Sir J. D., 4, 15, 16, 22,

23, 27, 40
Hose, C, 87
Huxley, T. H., 11, 52

Ireland, Mediterranean plants in,
30-38

Jeffrey, Prof. E. C, 114, 119
Jet, 114

Juan Fernandez, 84
Jurassic flora, 53, 54, 70, 117
Jussieu, A. de, 109

INDEX

141

Kaempfer, E., 121
Kauri Piue, 107
Kidston, Dr E., 74, 80
Knaresborongh, petrifying spring

at, (U
Krakatau, new flora of, 33, 31

Laccopteris, 90, 91
Lang, Dr A. , 27
Lankester, Sir Edwin Eay, 49
Lhywd, E., 57
Linnaeus, C, 121, 123
Liriodendron, 28, 29
Liverworts, antiquity of, 79
London Pride, 31
Longevity of trees, 1-10
Liizula racemosa, 23
L. spicata, 23, 24

MacDougal, Prof., 62

Maiden Hair Tree, 120-133

Mammoth trees of California,
95-105

Man, first appearance of, 49

Marchantia, 79

Market Harborough, Elodea dis-
covered near, 20

Marshall, E. S., 38

Matonia, 77, 86-94

M. pectiiiata, 86-88, 92, 93

M. sannentosa, 87

Matonidium, 89

Mediterranean plants in Ireland,
30-38

Miller, Hugh, 59, 115, 117

Milligan, Dr, 2

Moss, Dr C. E., 23

Mull, Fossil plants in Isle of, 132

Naias gr amine a, 21
Nathorst, A. G., 64, 103, 117
Native plants, 20

New forest, 31
Nipafruticans, 50-52
Nipadites, 50, 52
Norfolk Island Pine, see Arau-
caria excelsa

Oaks, longevitv of, 4
Oliver, Prof. F. W., 74
Osmunda regalis, 76-79, 83
Osmundites Dunlopi, 80

Palaeozoic plants, 55, 66-68, 71,

127, 128
Peat, trees in, 12, 13
Permian floras, 55
Petrifaction, 64-67
Picea excelsa, 46, 48
Pines, Tertiary, 65, 66
Pinus sylvestris, 11-13, 47
Pipewort, 36-38
Pliny's Natural History, 4
Podocarpus, 109
Potamogeton pennsylv aniens, 21
Praeger, E. L., 32, 36, 37
Pre-Glacial plants, 22, 45-48
Primula elatior, 24
Protodanimara, 119
Psygmophyllum, 127
Pteridium aquilinum, 75, 77, 83,

87
Pteridophyta, 18, 124
Pteridosperms, 74, 75
Pyreneau plants in Ireland, 31-38

Kay, John, 56

Reddish Canal, plants from the,

21
Eedwoods of California, 95-105
Eeid, Clement, 13, 22, 45, 102
Eeid, Mrs, 22, 102
Ehaetic plants, 54, 94
Riccia, 79

142

INDEX

Kidley, H. N., 25
Royal Fern, 76-79, 83
Rubus chamaentoriis, 22

St Dabeoc's Heath, 30, 32, 37

Salishuria adiantifolia, 122

Saporta, the Marquis of, 70

Saxifra(ja oppositifolia, 22

S. Kinbrosa, 31

Scandinavian plants in Britain,

21-23, 30
Scots Pine, see Pi)ius sylre-^tris
Scott, Dr D. H., 74
Sequoia, 5, 95-105
Sequoia Couttsiae, 101
S. gigantea, 5, 95, 96, 98-104
S. magnifica, 104
S. novae zeelandlcae, 105
S. semperviretis, 45, 96, 98, 104
Sheppey, fossil plants from, 50,

132
Shorea leprosula, 25
Silene acaulis, 22
Sisgriiichium angiistifoUiim, 38
S. californicuni, 38
Smith, G., 75
Smith, Sir J. E., 122, 123
Smith, W., 41
Sollas, Prof., 58
Spiranthes romanzojjiana, 38
Stellaria holostea, 4(i, 47
Steno, 57

Strahan, A., 13
Strawberry tree, 31, 32

Tansley, A. G., 12, 13, 87
Taxodium distichwn, 103
Tertiary plants, 31-33, 37, 49,

50, 103
Theobroma cacao, 7
Thyrsopteris elegans, 84
Todea harbara, 11,1^
T. r ad i cans, 78
Trapa natans, 47, 48
Triassic period, 54, 55
Tulip tree, 28

Walchia, 113

Wallace, Dr A. R., 85

Wealden flora, 17, 53

Weismann, A., 3

Wexford, American plant from, 38

Williamson, Prof. W. C, 72

Wilson, E. H., 120

Winchester Cathedral, wood from

foundations of, 10
Woodward, Dr J., 57
Woodworthia, 114

Yellowstone Park, fossil trees in
the, 59-61, 104

Zeiller, E., 113

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