TRANSCRIBER’S NOTE
Italic text is denoted by _underscores_.
Footnote anchors are denoted by [number], and the footnotes have
been placed at the end of the book.
Chapter headings have been made consistent, with the title on a
single line and the author on the following line.
Some minor changes to the text are noted at the end of the book.
Volume I of this set of four volumes can be found in Project
Gutenberg at: https://www.gutenberg.org/ebooks/74571
Volume II can be found in Project Gutenberg at:
https://www.gutenberg.org/ebooks/77792
[Illustration: Mushrooms and Other Fungi
1, Boletus Satanus; 2, Agaricus Muscarius; 3, Lycoperdon; 4,
Morchella Esculenta; 5, Belvella; 6, Agaricus Campestris; 7, Phallus;
8, Agaricus Phalloides; 9, Boletus Edulis; 10, Rhizopogon (_Truffle_)]
THE STORY OF
THE UNIVERSE
_Told by Great Scientists
and Popular Authors_
COLLECTED AND EDITED
_By_ ESTHER SINGLETON
Author of “Turrets, Towers and Temples,” “Wonders of Nature,”
“The World’s Great Events,” “Famous Paintings,” Translator
of Lavignac’s “Music Dramas of Richard Wagner”
_FULLY ILLUSTRATED_
VOLUME III
THE
EARTH’S
GARMENT:
FLORA
P. F. COLLIER AND SON
NEW YORK
COPYRIGHT 1905
BY P. F. COLLIER & SON
ILLUSTRATIONS
Mushrooms and Fungi _Frontispiece_
Familiar Trees _Opposite p._ 901
Herbs, Useful and Medicinal ” 949
Flowers, Curious and Beautiful ” 997
Cacti, Rare Flowers, and Fuci ” 1045
Cereals and Food Plants ” 1093
Bacteria and Vegetable Germs ” 1141
Nuts and Fruits ” 1213
Lichens ” 1261
CONTENTS
THE VEGETABLE KINGDOM. David Robertson 859
FLORA OF THE EARLY MESOZOIC. Sir J. William Dawson 871
EXISTING LIFE-FORMS OF PLANTS. Edward Clodd 887
PLANT GEOGRAPHY. Louis Figuier 898
ZONES OF VEGETATION. M. J. Schleiden 930
PHYSIOGNOMY OF PLANTS. Alexander von Humboldt 946
THE GENESIS OF FLOWERS. Alexander S. Wilson 957
LIFE HISTORY OF PLANTS. E. W. Prevost 968
LIFE-FORMS OF PLANTS. Edward Clodd 975
CLASSIFICATION OF PLANTS. Louis Figuier 984
FRUITS AND SEEDS. Lord Avebury 1002
LEAVES. R. Lloyd Praeger 1016
WIND-FERTILIZED FLOWERS. Alexander S. Wilson 1027
MOVEMENTS OF PLANTS. David Robertson 1037
MOVEMENT IN PLANTS. Charles Darwin 1045
FLOWER COLORATION. Alexander S. Wilson 1061
QUEER FLOWERS. Grant Allen 1068
ATHENA IN THE EARTH. John Ruskin 1077
PROGRESS OF CULTIVATION. Alphonse de Candolle 1091
VEGETABLE MIMICRY AND HOMOMORPHISM. Alexander S. Wilson 1099
THE BAMBOO AND PLANT GROWTH. R. Camper Day 1114
THE REIGN OF EVERGREENS. Grant Allen 1125
OUR MICROSCOPIC FOES. A. Winkelried Williams 1131
FOREST FORMATIONS. M. J. Schleiden 1135
THE HIGH WOODS. Charles Kingsley 1146
MILK-SAP PLANTS. M. J. Schleiden 1161
NUTS. Grant Allen 1174
THE CACTUS TRIBE. M. J. Schleiden 1180
FUNGI. Hugh Macmillan 1189
FAIRY RINGS. A. B. Steele 1204
LICHENS. Hugh Macmillan 1208
MOSSES. Hugh Macmillan 1220
EUROPEAN SEA-WEEDS. P. Martin Duncan 1230
SARGASSUM. Cuthbert Collingwood 1263
GLOSSARY OF BOTANICAL TERMS 1269
THE STORY OF THE UNIVERSE
(VOLUME THREE)
THE STORY OF THE UNIVERSE
THE VEGETABLE KINGDOM
--DAVID ROBERTSON
There is perhaps scarcely any science that can be more within the
reach of the means of the humblest student than the science of
botany. A pocket lens, a sharp penknife, and a book descriptive
of the flora of the district or country where one lives will form
a sufficient equipment to enable the student to name and classify
whatever plants he may meet with in his rambles in search of them.
It is by no means intended to imply that finding out the names of
plants and being able to classify them constitute the whole science
of botany. The truth is that many of the problems in connection with
classification are most abstruse, so much so that even now the most
recent and generally received system of classification can only be
considered provisional. This is especially the case in regard to the
lower forms of vegetable life. The life-history of many of the most
minute and lowly plants is but imperfectly known, owing to their
extreme minuteness and the different forms which they assume at the
various stages of their life-history.
This, however, does not detract from the pleasure which any one may
derive from being able to describe and name any flowering plants
which are to be found in any country at certain seasons.
The dependence of mankind on plants is too obvious to require mention.
To a large extent the vegetation of a district determines its
character; for without plants no landscape would possess any
particular attractiveness, and every one knows the depressing effect
produced by a barren, treeless waste. The contrast between this and
fields rich in pasture has occurred to every one; and a well-wooded
country never fails to please the eye of the observer.
Mighty forests, teeming with life, have a powerful influence on the
imagination; and the value of forests both as regards their effect
on climate and their economic importance has been so thoroughly
recognized that in the case of India stringent measures have been
adopted for their preservation.
Some knowledge of plant life also enables one to guard against the
evil and often fatal effects produced by eating poisonous fruits and
poisonous fungi.
Some of the lowly organized flowerless plants are man’s most deadly
and insidious enemies. These from their excessive minuteness are
quite invisible to the naked eye.
Before proceeding further, it will be necessary to give a brief
account of the different parts which go to compose the complete
flowering plant. The reader who desires a full and detailed account
of the different organs of the flowering and flowerless plants will
find this in any standard text-book of botany.
We will take any full-grown flowering plant and begin with the root.
The root may be called the descending portion of the axis.
The ascending portion of the axis is usually supplied with leaves,
flowers, and green coloring matter, whereas the root is usually
devoid of these.
The root generally penetrates into the soil and fulfils a double
function.
It is by means of the roots that the plant is attached to the earth
and prevented from being blown about by the winds.
In the case of large forest trees, the far-spreading roots have an
immense power of resistance. The large surface of a giant tree in
full leaf has to endure an enormous lateral pressure during a high
wind, and even hurricanes may fail to uproot a large tree, which they
may snap asunder. Not only does the root by penetrating the soil
attach the plant to the earth, but it absorbs nourishment from the
soil for the support of the plant. The root, therefore, fulfils a
double function.
The root is at first furnished with a conical hood of cellular
tissue, _i. e._, tissue consisting entirely of cells or little closed
bags made up of an outside wall and contents.
The root cup is well seen in some kinds of water-plants, such as
duckweed.
There are plants whose roots do not descend. Certain plants hang
from the branches of trees, and though they have roots these roots
never penetrate the soil. Plants of this kind are called Epiphytes
(Greek _epi_, upon, and _phyton_, plant). Aerial orchids, which grow
in warm and moist parts of India and other countries, are attached
to branches of trees or other kinds of support, and their roots hang
down from the peculiar stems and are very soft and delicate at the
tips.
It must be borne in mind that there is no absolute distinction
between root and stem; for some trees have roots which form lateral
buds, viz., _Pyrus japonica_, _Maclura aurantiaca_, and many others.
This is quite in accordance with the fact that in the organic world
different organs frequently shade into one another.
The true root of the plant in its earliest state of existence, that
is, as it exists in the seed prior to germination, is the downward
prolongation of the axis.
In the case of the division of flowering plants called Monocotyledons
(Greek _monos_, single, and _kotyledon_, seed-leaf), and in such
so-called flowerless plants as ferns, the lower end of the axis
soon ceases to grow and the roots which supply these plants with
nourishment are really lateral growths. The roots of plants are
variously named. Sometimes the branches of the roots are small, and
the central axis thick and of considerable length. This kind of root
is named a tap-root, and may be well seen in the carrot.
In the turnip, beet, and other plants, where this organ is developed
in such a manner as to serve as a reservoir of nutriment, the root is
tuberous.
Many roots are fibrous; this may be well seen in grasses.
The perennial woody forms of fibrous roots are very characteristic of
shrubby Dicotyledons (plants with two seed-leaves).
Leaves are of two kinds, namely, foliage-leaves and flower-leaves.
A leaf is generally a broad, flat, horizontal surface. It is usually
thin, and can be divided by a perpendicular plane, the median plane,
into two similar halves.
When the leaves are what is called symmetrical, the parts into which
they are divided are counterparts.
If one of these parts were held in front of a looking-glass, the
reflected image of this part would represent the part from which it
had been separated.
Many leaves, however, can not thus be divided. When this is the case
they are said to be unsymmetrical.
The tropical plant begonia affords an excellent example of an
unsymmetrical leaf.
The leaves of the spruce are not flat but needle-shaped.
In rushes and many species of stone-crops the leaves are cylindrical
or round.
The leaf consists of three parts, viz., the sheath, the stalk or
petiole, and the lamina or blade. The sheath incloses the stem at
the insertion of the leaf, and has a tubular or sheath-like form. It
is well seen in grasses and such plants as celery, corn, parsnip,
carrot, and other plants belonging to the _Umbelliferæ_ [Lat.
_umbella_ (_umbra_, shade), little shade, and _ferre_, to bear].
The leaf-stalk is narrow, and has a semi-cylindrical or prismatic
form, bearing at its end the expanded leaf.
When the stalk is flattened and resembles a leaf, as in the case of
the Australian acacias, it is termed a phyllode (Greek _phyllon_, a
leaf, and _eidos_, form).
Many leaves have no sheath, but only the stalk and the blade. This is
the case in the maple and gourd.
The leaves of the grasses have no stalk, but only sheath and blade.
The blade is often the only part present, as in the tobacco plant and
tiger-lily. Small appendages, looked upon as belonging to the sheath,
are frequently present, and are termed stipules (from Lat. _stipula_,
blade). Leaves having these appendages are called stipulate, and
leaves devoid of them are exstipulate (from Lat. _ex_, privative,
without, and _stipula_, blade).
A few plants, such as grasses, have a small outgrowth from the inner
upper surface of the leaf at the part where the sheath and the blade
are joined. This outgrowth is named a ligule (from Lat. _ligula_, a
little tongue).
If a leaf is carefully examined it will be found that the internal
tissues differ in character. The fundamental tissue is generally
green, and is named the messophyll (Greek, _mesos_, or _messos_,
middle, and _phyllon_, leaf).
It will be seen that bands run through the fundamental tissue called
the veins of the leaf. These veins consist of what are termed
fibro-vascular bundles. They endure longer than the fundamental
tissue, and may frequently be seen after the leaf is withered and
dead, forming the skeleton of the leaf.
The arrangement of the veins or fibro-vascular bundles is
characteristic of large groups of plants.
In the narrow linear leaves of grasses the stronger veins run almost
parallel. In broad leaves, such as those of the lily-of-the-valley,
the veins curve, but do not form a network of tracery as in oaks
and other Dicotyledons. The margin of leaves is frequently divided,
but the technical terms used in describing such leaves can be found
in any text-book of botany. They may either be simple or compound.
A simple leaf consists of a single lamina, however much it may be
divided, provided the divisions do not extend to the central vein or
midrib. A leaf is compound when, besides the principal leaf-stalks,
a number of lateral leaf-stalks exist bearing at their ends laminæ.
The leaves of many plants are compound. The sensitive plant (_Mimosa
pudica_) furnishes an excellent example of the compound leaf.
The characteristic color of foliage leaves is green, and they are so
arranged as to receive as much sunlight as possible. The importance
of the plant receiving a good supply of light will be referred to
when treating of the growth of plants. It is as true of plants as
of animals that the organs most suitable for their surroundings
are so arranged as to be most advantageous to the individual. Had
leaves been placed vertically they would only have received diffused
sunlight instead of the direct rays of the sun. No vegetable life
could exist but for the sun, as plants not only require light but
heat as well.
When the foliage leaves are small they are very numerous, as may be
seen in conifers; and when these leaves are large they are not nearly
so numerous as, for example, in the sunflower.
Sometimes leaves may consist of scales. These scales are always found
on stems growing underground, as in the onion; but they sometimes
occur on stems growing above-ground.
Such plants as _Orobanche_ and _Neottia_ have no other kind of leaves
except scales.
The leaves are developed very near the apex of the growing stem.
The portions of the stem which lie between the leaves are termed the
internodes, and the parts where the leaves are inserted are termed
the nodes.
Leaves are arranged in various ways, intimately connected with the
order of their development. They may be developed so that three or
more are at the same level on the stem; this arrangement is termed a
_whorl_. Or they may be developed singly; this arrangement is termed
_scattered_. For a full account of the various leaf-arrangements any
text-book on botany may be consulted.
We have here merely referred to some of the more obvious arrangements
of the leaves.
Certain leaves possess a remarkably abnormal shape; for example,
stone-crops have cylindrical leaves; if the leaf of an agave is cut
across, the section is triangular; leeks, again, are tube-shaped; the
central cavity being due to the rapid growth of the outer tissue.
These leaves are all juicy or succulent; certain other leaves are
leathery, that is, they have a harder and thicker epidermis than the
succulent leaves, and may last for several years, as, for example, in
the holly and box.
Spines and tendrils are modifications of leaves, or parts of leaves.
The tendrils are formed out of entire leaves, midribs, leaflets, or
stipules. Both spines and tendrils, however, may be modified branches
of the stem.
In buds the leaves are packed or folded in various ways. This is
best seen before the buds are opened in spring. The buds may then be
pulled carefully to pieces, and in this way the manner in which the
leaves are folded can be studied.
We now come to the flower.
Flowers consist of leaves modified in different ways.
Take, for example, the flower of the orange. The flower will be seen
to be borne on a short branch which serves as the stalk, and is
distinguished by the name of peduncle (from Lat. _pedunculus_, little
stalk). It will be seen that there are no internodes between the
flower-leaves.
The lowest and outermost part of the flower forms a little cup having
upon its margin fine small teeth, indicating the number of leaves
which are joined together so as to form the cup or calyx.
These leaves are named (from Lat. _calyx_, a covering; Greek _kalyx_,
from _kalyptein_, to cover) the calyx-leaves, or sepals (French
_sépale_). Although they are united in the flower of the orange,
they are often separate in other plants.
In the sacred Lotus or Padma or Pudma of India the sepals are
separate or free. The leaves immediately inside the calyx are usually
five in number. They are erect, or only slightly curved, and do
not grow together like the leaves of the calyx. They are white and
wax-like. These leaves form together what is termed the corolla, and
the separate leaves of the corolla (from Lat. _corolla_, a little
wreath) are termed petals (from Greek _petalon_, leaf). In the case
of the orange the petals fall early away.
If the calyx and petals are carefully removed, the next part of the
flower can be observed.
This series of flower-leaves differs very much in structure from both
sepals and petals. Each leaf of this series consists of a linear
stalk-like portion, bearing an upper somewhat long and grooved head.
The stalk is named the filament, and the oblong head is named the
anther (Greek _anthos_, a flower). The stalk and the head together
form what is called the stamen (Lat. _stamen_, [Greek _histanai_,
to stand] fibre; literally, the warp in the upright loom of the
ancients). The stamens of the orange are rather shorter than the
petals, and are united to each other.
When the anther is mature, each of its grooves splits near the edge,
and allows the fine powdery granules which fill the anthers to be
removed by insects or by other means. This fine powder is named the
pollen, and each of the granules composing it is named a pollen
grain. If the stamens are now removed the centre of the flower alone
is left.
If the lower part of the centre of the flower be cut across, it will
be found to be divided into a large number of cavities containing
the minute rudiments of future seeds. It will be seen that there are
ten cavities, though they may vary in number. The central organ of
the flower is named the pistil (from Lat. _pistillum_, pestle). The
pistil is usually composed of united leaves.
The separate leaves of the pistil are termed carpels (from Greek
_karpos_, fruit). These leaves are sometimes not combined, as they
are in the orange. The style belongs to the carpel, and varies
considerably in length, as well as in stoutness, in different
flowers. Although the carpels may be united, the styles may remain
completely separate, as, for example, in the pink, or, as in the
fuchsia, they may be combined into a single rod.
The pollen grains (Lat. fine flour) contained in the anther are
composed of very rich protoplasm (Greek _protos_, first; _plasma_,
formative matter), which usually has in it small drops of oil and
small starch granules. The pollen grains are bounded by two principal
layers, an outer and an inner; the purpose of the outer layer (which
is often provided with thickenings in the shape of knots, spines,
etc.) being to preserve the contents of the grain from evaporation.
The inner layer is living and capable of growth, and at certain
spots it possesses thickenings which project into the protoplasm.
Opposite to these the external cuticle is frequently thinner, and
this eventually is lifted off as a sort of lid, and through this the
inner substance can grow out, and is then named the pollen tube.
When the anther lobes open to discharge their pollen grains, these
grains are completely developed.
The grains fall on the part of the ovary named the stigma (Greek
_stigma_, a puncture made with a sharp instrument; here it means a
sharp point or apex) and the inner layer begins to force its way out.
The tube is produced from the contents of the pollen grain, and is
formed by growth, just as any other part of the plant. The pollen
tube passes down to the ovules, the route depending on the length of
the style. The time taken by the pollen tube to reach the ovary may
amount to a few hours in certain plants, while it needs months in
others. It is necessary that at least one pollen tube should enter
the mouth of the ovule before it can develop into a seed. The seed,
when mature, contains the embryo plant.
It is not possible for an ovule in numerous cases to be fertilized by
pollen from stamens that grow near it in the same flower.
It not unfrequently happens that a flower possesses stamens and
no pistil, or a pistil and no stamens. Flowers of this kind are
technically termed diœcious (Greek _dis_, twice, and _oikia_ or
_oikos_, place of abode), if the male and female flowers are on
different plants. The flowers of such plants as oaks and birches
are male and female, but are borne on the same plant, hence termed
monœcious (Greek _monos_, single). The flowers that contain stamens
only are called male flowers, and those containing pistils only are
named female flowers.
The oaks and birches, as has been stated, have both the male and
female flowers on the same plant, though in other cases the male
flower is borne on one plant and the female flower on another.
In cases like these the wind carries the pollen from one plant to
another. In wind-fertilized flowers the flower is usually produced
prior to the foliage leaves, or at least before the plant is crowded
with leaves.
These plants produce an immense amount of pollen.
Besides the transference of pollen by the agency of the wind, insect
agency plays a very important part. These insect-fertilized plants
are much more conspicuous than those fertilized by the wind.
There are numerous natural contrivances in plants to prevent
self-fertilization, as this process of self-fertilization is far less
effective in producing seeds than when the ovules are fertilized by
pollen from another plant of the same species.
In some plants the stigma is mature before the anther, and in such
a case the pollen must be brought from a flower that has bloomed a
little earlier than itself.
FLORA OF THE EARLY MESOZOIC
--SIR J. WILLIAM DAWSON
Great physical changes occurred at the close of the Carboniferous
age. The thick beds of sediment that had been accumulating in long
lines along the primitive continents had weighed down the earth’s
crust. Slow subsidence had been proceeding from this cause in the
coal-formation period, and at its close vast wrinklings occurred,
only surpassed by those of the old Laurentian time. Hence in the
Appalachian region of America we have the Carboniferous beds thrown
into abrupt folds, their shales converted into hard slates, their
sandstones into quartzite and their coals into anthracite, and all
this before the deposition of the Triassic Red Sandstones which
constitute the earliest deposit of the great succeeding Mesozoic
period. In like manner the coal-fields of Wales and elsewhere in
western Europe have suffered similar treatment, and apparently at the
same time.
This folding is, however, on both sides of the Atlantic limited to a
band on the margin of the continents, and to certain interior lines
of pressure, while in the middle, as in Ohio and Illinois in America,
and in the great interior plains of Europe, the coal-beds are
undisturbed and unaltered. In connection with this we have an entire
change in the physical character of the deposits, a great elevation
of the borders of the continents, and probably a considerable
deepening of the seas, leading to the establishment of general
geographical conditions which still remain, though they have been
temporarily modified by subsequent subsidences and re-elevations.
Along with this a great change was in progress in vegetable and
animal life. The flora and fauna of the Palæozoic gradually die out
in the Permian and are replaced in the succeeding Trias by those of
the Mesozoic time. Throughout the Permian, however, the remains of
the coal-formation flora continue to exist, and some forms, as the
_Calamites_, even seem to gain in importance, as do also certain
types of coniferous trees. The Triassic, as well as the Permian, was
marked by physical disturbances, more especially by great volcanic
eruptions discharging vast beds and dikes of lava, and layers of
volcanic ash and agglomerate. This was the case more especially
along the margins of the Atlantic, and probably also on those of
the Pacific. The volcanic sheets and dikes associated with the Red
Sandstones of Nova Scotia, Connecticut, and New Jersey are evidences
of this.
At the close of the Permian and beginning of the Trias, in the
midst of this transition time of physical disturbance, appear the
great reptilian forms characteristic of the age of reptiles, and
the earliest precursors of the mammals, and at this time the old
Carboniferous forms of plants finally pass away, to be replaced by
a flora scarcely more advanced, though different, and consisting
of pines, cycads, and ferns, with gigantic equiseta, which are the
successors of the genus _Calamites_, a genus which still survives
in the early Trias. Of these groups the conifers, the ferns, and
the equiseta are already familiar to us, and, in so far as they are
concerned, a botanist who had studied the flora of the Carboniferous
would have found himself at home in the succeeding period. The cycads
are a new introduction. The whole, however, come within the limits of
the cryptogams and the gymnosperms, so that here we have no advance.
As we ascend, however, in the Mesozoic, we find new and higher
types. Even within the Jurassic epoch, the next in succession to
the Trias, there are clear indications of the presence of the
endogens, in species allied to the screw-pines and grasses; and the
palms appear a little later, while a few exogenous trees have left
their remains in the Lower Cretaceous, and in the Middle and Upper
Cretaceous these higher plants come in abundantly and in generic
forms still extant, so that the dawn of the modern flora belongs
to the Middle and Upper Cretaceous. It will thus be convenient
to confine ourselves in this chapter to the flora of the earlier
Mesozoic.
Passing over for the present the cryptogamous plants already familiar
in older deposits, we may notice the new features of gymnospermous
and phænogamous life, as they present themselves in this earlier part
of the great reptilian age, and as they extended themselves with
remarkable uniformity in this period over all parts of the world. For
it is a remarkable fact that, if we place together in our collections
fossil plants of this period from Australia, India, China, Siberia,
Europe, or even from Greenland, we find wonderfully little difference
in their aspect. This uniformity prevailed in the Palæozoic flora;
and it is perhaps equally marked in that of the Mesozoic. Still
we must bear in mind that some of the plants of these periods, as
the ferns and pines, for example, are still world-wide in their
distribution; but this does not apply to others, more especially the
cycads.
The cycads constitute a singular and exceptional type in the modern
world, and are limited at present to the warmer climates, though
very generally distributed in these, as they occur in Africa, India,
Japan, Australia, Mexico, Florida, and the West Indies. In the
Mesozoic age, however, they were world-wide in their distribution,
and are found as far north as Greenland, though most of the species
found in the Cretaceous of that country are of small size, and may
have been of low growth, so that they may have been protected by the
snows of winter. The cycads have usually simple or unbranching stems,
pinnate leaves borne in a crown at top, and fruits which, though
somewhat various in structure and arrangement, are all of the simpler
form of gymnospermous type. The stems are exogenous in structure, but
with slender wood and thick bark, and barred tissue, or properly as
tissue intermediate between this and the disk-bearing fibres of the
pines.
The greater part of the cycads of the Mesozoic age would seem to
have had short stems and to have constituted the undergrowth of
woods in which conifers attained to greater height. An interesting
case of this is the celebrated dirt-bed of the quarries of the Isle
of Portland, long ago described by Dean Buckland. In this fossil
soil trunks of pines, which must have attained to great height, are
interspersed with the short, thick stems of cycads, of the genus
named _Cycadoidea_ by Buckland, and which from their appearance are
called “fossil birds’ nests” by the quarrymen. Some, however, must
have attained a considerable height so as to resemble palms.
The cycads, with their simple, thick trunks, usually marked
with rhombic scars, and bearing broad spreading crowns of large,
elegantly formed pinnate leaves, must have formed a prominent part
of the vegetation of the Northern Hemisphere during the whole of
the Mesozoic period. A botanist, had there been such a person at
the time, would have found this to be the case everywhere from the
equator to Spitzbergen, and probably in the Southern Hemisphere as
well, and this throughout all the long periods from the Early Trias
to the Middle Cretaceous. In a paper published in the _Linnæan
Transactions_ for 1868, Dr. Carruthers enumerates twenty species of
British Mesozoic cycads, and the number might now be considerably
increased.
The pines present some features of interest. In the Mesozoic we have
great numbers of beautiful trees, with those elegant fan-shaped
leaves characteristic of but one living species, the _Salisburia_,
or gingko-tree of China. It is curious that this tree, though now
limited to eastern Asia, will grow, though it rarely fruits, in most
parts of temperate Europe, and in America as far north as Montreal,
and that in the Mesozoic period it occupied all these regions, and
even Siberia and Greenland, and with many and diversified species.
_Salisburia_ belongs to the yews, but an equally curious fact applies
to the cypresses. The genus _Sequoia_, limited at present to two
species, both Californian, and one of them the so-called “big tree,”
celebrated for the gigantic size to which it attains, is represented
by species found as far back at least as the Lower Cretaceous, and in
every part of the Northern Hemisphere.[1] It seems to have thriven
in all these regions throughout the Mesozoic and early Kainozoic, and
then to have disappeared, leaving only a small remnant to represent
it in modern days. A number of species have been described from the
Mesozoic and Tertiary, all of them closely related to those now
existing.
The name itself deserves consideration. It is that of an Indian of
the Cherokee tribe, Sequo Yah, who invented an alphabet without
any aid from the outside world of culture, and taught it to his
tribe by writing it upon leaves. This came into general use among
the Cherokees before the white man had any knowledge of it; and
afterward, in 1828, a periodical was published in this character by
the missionaries. Sequo Yah was banished from his home in Alabama,
with the rest of his tribe, and settled in New Mexico, where he died
in 1843.
When Endlicher was preparing his synopsis of the conifers, in 1846,
and had established a number of new genera, Dr. Jacbon Tschudi, then
living with Endlicher, brought before his notice this remarkable
man, and asked him to dedicate this red-wooded tree to the memory
of a literary genius so conspicuous among the red men of America.
Endlicher consented to do so, and only endeavored to make the name
pronounceable by changing two of its letters.
Endlicher founded the genus on the redwood of the Americans,
_Taxodium sempervirens_ of Lamb; and named the species _Sequoia
sempervirens_. These trees form large forests in California, which
extend along the coast as far as Oregon. Trees are there met with of
300 feet in height and 20 feet in diameter. The seeds were brought to
Europe a number of years ago, and we already see in upper Italy and
around the Lake of Geneva, and in England, high trees; but, on the
other hand, they have not proved successful around Zurich.
In 1852, a second species of Sequoia was discovered in California,
which, under the name of big tree, soon attained a considerable
celebrity. Lindley described it, in 1853, as _Wellingtonia gigantea_;
and, in the following year, Decaisne and Torrey proved that it
belonged to Sequoia, and that it accordingly should be called
_Sequoia gigantea_.
While the _Sequoia sempervirens_, in spite of the destructiveness of
the American lumbermen, still forms large forests along the coasts,
the _Sequoia gigantea_ is confined to the isolated clumps which are
met with inland at a height of 5,000 to 7,000 feet above sea-level,
and are much sought after by tourists as one of the wonders of the
country. Reports came to Europe concerning the largest of them which
were quite fabulous, but we have received accurate accounts of them
from Professor Whitney. The tallest tree measured by him has a height
of 325 feet, and in the case of one of the trees the number of the
rings of growth indicated an age of about 1,300 years. It had a girth
of 50 to 60 feet.
We know only two living species of _Sequoia_, both of which are
confined to California. The one (_S. sempervirens_) is clothed with
erect leaves, arranged in two rows, very much like our yew-tree,
and bears small, round cones; the other (_S. gigantea_) has smaller
leaves, set closely against the branches, giving the tree more the
appearance of the cypress. The cones are egg-shaped, and much larger.
These two types are, therefore, sharply defined.
Both of these trees have an interesting history. If we go back into
the Tertiary, this same genus meets us with a long array of species.
Two of these species correspond to those living at present: the _S.
Langsdorfii_ to the _S. sempervirens_, and the _S. Couttsiæ_ to
the _S. gigantea_. But, while the living species are confined to
California, in the Tertiary they are spread over several quarters of
the globe.
Let us first consider the _Sequoia Langsdorfii_. This was first
discovered in the lignite of Wetterau, and was described as _Taxites
Langsdorfii_. Heer found it in the upper Rhone district, and there
lay beside the twigs the remains of a cone, which showed that the
_Taxites Langsdorfii_ of Brongniart belonged to the Californian genus
_Sequoia_ established by Endlicher. He afterward found much better
preserved cones, together with seeds, along with the plants of east
Greenland, which fully confirmed the determination. At Atanekerdluk
in Greenland (about 70° north latitude) this tree is very common.
The leaves, and also the flowers and numerous cones, leave no doubt
that it stands very near to the modern redwood. It differs from it,
however, in having a much larger number of scales in the cone. The
tree is also found in Spitzbergen at nearly 78° north latitude, where
Nordenskiöld has collected, at Cape Lyell, wonderfully preserved
branches. From this high latitude the species can be followed down
through the whole of Europe as far as the middle of Italy (at
Senegaglia, Gulf of Spezia). In Asia, also, we can follow it to
the steppes of Kirghisen, to Possiet, and to the coast of the sea
of Japan, and across to Alaska and Sitka. It is recognized by Mr.
Starkie Gardner as one of the species found in the Eocene of Mull in
the Hebrides. It is thus known in Europe, Asia, and America from 43°
to 78° north latitude, while its most nearly related living species,
perhaps even descended from it, is now confined to California.
With this _S. Langsdorfii_, three other Tertiary species are
nearly related (_S. brevifolia_, Hr., _S. disticha_, Hr., and _S.
Nordenskiöldi_, Hr.). These have been met with in Greenland and
Spitzbergen and one of them has been found in the United States.
Three other species, in addition to these, have been described
by Lesquereux, which appear to belong to the group of the _S.
Langsdorfii_, viz., _S. longifolia_, Lesq., _S. angustifolia_, and
_S. acuminata_, Lesq. Several species also occur in the Cretaceous
and Eocene of Canada.
These species thus answer to the living _Sequoia sempervirens_; but
we can also point to Tertiary representatives of the _S. gigantea_.
Their leaves are stiff and sharp-pointed, are thinly set round the
branches, and lie forward in the same way: the egg-shaped cones are
in some cases similar.
There are, however, in the early Tertiary six species, which fill
up the gap between _S. sempervirens_ and _S. gigantea_. They are
the _S. Couttsiæ_, _S. affinis_, Lesq., _S. imbricata_, Hr., _S.
sibirica_, Hr., _S. Heerii_, Lesq., and _S. biformis_, Lesq. Of
these, _S. Couttsiæ_, Hr., is the most common and most important
species. It has short leaves, lying along the branch, like _S.
gigantea_, and small, round cones, like _S. Langsdorfii_ and
_sempervirens_. Bovey Tracey in Devonshire has afforded splendid
specimens of cones, seeds, and twigs, which have been described in
the _Philosophical Transactions_. More lately, Count Saporta has
described specimens of cones and twigs from Armissan. Specimens of
this species have also been found in the older Tertiary of Greenland,
so that it must have had a wide range. It is very like to the
American _S. affinis_, Lesq.
In the Tertiary there have been found fourteen well-marked species,
which thus include representatives of the two living types, _S.
sempervirens_ and _S. gigantea_.
We can follow this genus still further back. If we go back to the
Cretaceous age, we find ten species, of which five occur in the
Urgon of the Lower Cretaceous, two in the Middle, and three in the
Upper Cretaceous. Among these, the Lower Cretaceous exhibits the two
types of the _Sequoia sempervirens_ and _S. gigantea_. To the former
the _S. Smithiana_ answers, and to the latter, the _Reichenbachii_,
Gein. The _S. Smithiana_ stands indeed uncommonly near the _S.
Langsdorfii_, both in the appearance of the leaves on the twigs and
in the shape of the cones. These are, however, smaller, and the
leaves do not become narrower toward the base. The _S. pectina_,
Hr., of the Upper Cretaceous, has its leaves arranged in two rows,
and presents a similar appearance. The _S. Reichenbachii_ is a type
more distinct from those now living and those in the Tertiary.
It has indeed stiff, pointed leaves, lying forward, but they are
arcuate, and the cones are smaller. This tree has been known for
a long time, and it serves in the Cretaceous as a guiding star,
which we can follow from the Urgonian of the Lower Cretaceous up to
the Cenomanian. It is known in France, Belgium, Bohemia, Saxony,
Greenland, and Spitzbergen (also in Canada and the United States). It
has been placed in another genus--Geinitzia--but we can recognize, by
the help of the cones, that it belongs to Sequoia.
Below this, there is found in Greenland a nearly related species, the
_S. ambigua_, Hr., of which the leaves are shorter and broader, and
the cones round and somewhat smaller.
The connecting link between _S. Smithiana_ and _Reichenbachii_ is
formed by _S. subulata_, Hr., and _S. rigida_, Hr., and three species
(_S. gracilis_, Hr., _S. fastigiata_ and _S. Gardneriana_, Carr.),
with leaves lying closely along the branch, and which come very near
to the Tertiary species _S. Couttsiæ_. We have, therefore, in the
Cretaceous quite an array of species, which fill up the gap between
the _S. sempervirens_ and _gigantea_, and show us that the genus
Sequoia had already attained a great development in the Cretaceous.
This was still greater in the Tertiary, in which it also reached its
maximum of geographical distribution. Into the present world the two
extremes of the genus have alone continued; the numerous species
forming its main body have fallen out in the Tertiary.
If we look still further back, we find in the Jura a great number
of conifers, and, among them, we meet in the genus Pinus with a
type which is highly developed, and which still survives; but for
Sequoia we have till now looked in vain, so that for the present
we can not place the rise of the genus lower than the Urgonian of
the Cretaceous, however remarkable we may think it that in that
period it should have developed into so many species; and it is
still more surprising that two species already make their appearance
which approach so near to the living _Sequoia sempervirens_ and _S.
gigantea_.
Altogether, we have become acquainted, up to the present time, with
twenty-six species of Sequoia. Fourteen of these species are found
in the Arctic zone, and have been described and figured in the
_Fossil Flora of the Arctic Regions_. Sequoia has been recognized by
Ettingshausen even in Australia, but there in the Eocene.
This is, perhaps, the most remarkable record in the whole history of
vegetation. The Sequoias are the giants of the conifers, the grandest
representatives of the family; and the fact that, after spreading
over the whole Northern Hemisphere and attaining to more than twenty
specific forms, their decaying remnant should now be confined to one
limited region in western America[2] and to two species constitutes
a sad memento of departed greatness. The small remnant of _S.
gigantea_ still, however, towers above all competitors as eminently
the “big trees”; but, had they and the allied species failed to
escape the Tertiary continental submergences and the disasters of the
glacial period, this grand genus would have been to us an extinct
type. In like manner the survival of the single gingko of eastern
Asia alone enables us to understand that great series of taxine trees
with fern-like leaves of which it is the sole representative.
Besides these peculiar and now rare forms, we have in the Mesozoic
many others related closely to existing yews, cypresses, pines, and
spruces, so that the conifers were probably in greater abundance and
variety than they are at this day.
In this period also we find the earliest representatives of the
endogenous plants. It is true that some plants found in the
coal-formation have been doubtfully referred to these, but the
earliest certain examples would seem to be some bamboo-like and
screw-pine-like plants occurring in the Jurassic rocks. Some of
these are, it is true, doubtful forms, but of others there seems to
be no question. The modern _Pandanus_ or screw-pine of the tropical
regions, which is not a pine, however, but a humble relation of the
palms, is a stiffly branching tree, of a candelabra-like form, and
with tufts of long leaves on its branches, and nuts or great hard
berries for fruit, borne sometimes in larger masses, and so protected
as to admit of their drifting uninjured on the sea. The stems are
supported by masses of aerial roots like those which strengthen the
stems of tree-ferns. These structures and habits of growth fit the
Pandanus for its especial habitat on the shores of tropical islands,
where its masses of nuts are drifted by the winds and currents, and
on whose shores it can establish itself by the aid of its aerial
roots.
Some plants referred to the cycads have proved veritable botanical
puzzles. One of these, the _Williamsonia gigas_ of the English
oölite, originally discovered by my friend, Dr. Williamson, and
named by him _Zamia gigas_, a very tall and beautiful species, found
in rocks of this age in various parts of Europe, has been claimed
by Saporta for the Endogens, as a plant allied to _Pandanus_. Some
other botanists have supposed the flowers and fruits to be parasites
on other plants, like the modern _Rafflesia_ of Sumatra, but it is
possible that after all it may prove to have been an aberrant cycad.
The tree-palms are not found earlier than the Middle Cretaceous. In
like manner, though a few Angiosperms occur in rocks believed to
be Lower or Lower Middle Cretaceous in Greenland and the Northwest
Territory of Canada, and in Virginia, these are merely precursors of
those of the Upper Cretaceous, and are not sufficient to redeem the
earlier Cretaceous from being a period of pines and cycads.
On the whole, this early Mesozoic flora, so far as known to us, has
a monotonous and mean appearance. It no doubt formed vast forests
of tall pines, perhaps resembling the giant Sequoias of California;
but they must for the most part have been dark and dismal woods,
probably tenanted by few forms of life, for the great reptiles of
this age must have preferred the open and sunny coasts, and many of
them dwelt in the waters. Still we must not be too sure of this. The
berries and nuts of the numerous yews and cycads were capable of
affording much food. We know that in this age there were many great
herbivorous reptiles, like _Iguanodon_ and _Hadrosaurus_, some of
them fitted by their structure to feed upon the leaves and fruits of
trees. There were also several kinds of small herbivorous mammals,
and much insect life, and it is likely that few of the inhabitants of
the Mesozoic woods have been preserved as fossils. We may yet have
much to learn of the inhabitants of these forests of ferns, cycads,
and pines. We must not forget in this connection that in the present
day there are large islands, like New Zealand, destitute of mammalia,
and having a flora comparable with that of the Mesozoic in the
Northern Hemisphere, though more varied. We have also the remarkable
example of Australia, with a much richer flora than that of the early
Mesozoic, yet inhabited only by non-placental mammals, like those of
the Mesozoic.
The principal legacy that the Mesozoic woods have handed down to our
time is in some beds of coal, locally important, but of far less
extent than those of the Carboniferous period. Still, in America,
the Richmond coal-field in Virginia is of this age, and so are the
anthracite beds of the Queen Charlotte Islands, on the west coast
of Canada, and the coal of Brora in Sutherlandshire. Valuable beds
of coal, probably of this age, also exist in China, India, and
South Africa; and jet, which is so extensively used for ornament, is
principally derived from the carbonized remains of the old Mesozoic
pines.
EXISTING LIFE-FORMS OF PLANTS
--EDWARD CLODD
Plants are divided into two main groups or sub-kingdoms: I,
_Cryptogams_ (Greek _Kruptos_, hidden; _gamos_, marriage), or
flowerless; II, _Phanerogams_ (Greek _phaneros_, open; _gamos_,
marriage), or flowering.
I. The _Cryptogams_ comprise as their leading representatives: 1.
Algæ, Fungi, Lichens; 2. Liverworts, Mosses; 3. Ferns, Horsetails,
Club-mosses.
The feature common to these is the absence of any conspicuous organs;
_i. e._, true flowers with stamens and pistils for the production of
seeds or fruits. The simplest or single-celled plants increase by
subdivision, each cell carrying on an independent life and repeating
the process of division. But sexuality is manifest in plants very
low down in the scale, the mode of reproduction varying a good deal
in different species. In some cryptogams it is almost as complex as
in the flowering plants, but notwithstanding the different kinds of
sexual organs, there is this fundamental resemblance between them,
that the union of the contents of two cells, a male or sperm-cell,
and a female or germ-cell, each of which is by itself incapable of
further development, is essential to the production of the embryo or
seed.