tropical arborescent grass which bears the name of bamboo. Although
it is not cultivated for the sake of its seed, it has many admirable
qualities, and wherever it grows in abundance it is applied to a
variety of uses. “The strength, lightness, smoothness, straightness,
roundness, and hollowness of the bamboo,” says Mr. A. R. Wallace in
his _Malay Archipelago_, “the facility and regularity with which they
can be split, their many different sizes, the varying length of their
joints, the ease with which they can be cut and with which holes can
be made through them, their hardness outside, their freedom from any
pronounced taste or smell, their great abundance, and the rapidity of
their growth and increase, are all qualities which render them useful
for a hundred different purposes, to serve which other materials
would require much more labor and preparation. The bamboo is one of
the most wonderful and beautiful productions of the tropics, and one
of nature’s most valuable gifts to uncivilized man.”
In order that the accuracy of this eulogy may be appreciated,
let us imagine the case of a shipwrecked man landing without any
tools, except an axe and a knife, upon an island in which we will
suppose the bamboos are the only vegetation, and let us see how far
he could supply his needs with their assistance. One of his first
requirements would be a house, and this could be provided with very
little labor. The stems of one of the larger species, such as Bambusa
Brandisii, driven into the ground, would form excellent uprights for
the framework, which could be completed with lighter cross-pieces
nailed to the uprights with pegs of the same material. A good roof
could be made by taking broad strips split from large bamboos, and
fastening them side by side with their concave surfaces uppermost,
the interstices between them being covered with other pieces having
their convex sides uppermost. Similar but flatter pieces laid upon
the joists, and tied down firmly with strips shredded from the outer
rind, would form a smooth and elastic floor such as could not be made
out of other materials without a great expenditure of labor. Thin
strips plaited together, or broad strips pegged side by side, might
be used for the walls.
The furnishing of the house would be an easy matter, for bedsteads,
chairs, brooms, baskets, cords, fans, bottles, mats, and hoes can be
made of bamboo with the greatest facility. The water-tight joints
of the stems form admirable water-vessels, and it would be easy to
bring the water to the very door by a gently sloping aqueduct of
pieces of bamboo split down the middle and supported at intervals
on cross-pieces arranged like the letter X. The jars made from the
joints could be utilized not only for holding water, but even for
boiling it. Mr. Wallace tells us that rice, fish, and vegetables
can be boiled in them to perfection. The young shoots of the bamboo
as they first spring from the ground are said to be a delicious
vegetable, “quite equal to artichokes.” That fish may be readily
caught by the agency of the bamboo is shown by the many specimens
of ingenious fish-traps exhibited in the museum at Kew. If we
suppose our adventurer to take a thin stem of bamboo, and cut off
the end obliquely just above a joint so as to leave a sharp edge,
he would be provided with a hard-pointed and very efficient spear.
In the same way he could supply himself with daggers and arrows;
while from the more elastic species he could make himself a bow,
using a thin strip of the outer rind for a bow-string. The lowest
internode of Arthrosylidium Schomburgkii, which sometimes attains the
extraordinary length of sixteen feet, far surpassing the length of
the joints in all other bamboos (says General Munro), furnishes the
“Sarbican” or blow-pipe through which poisoned arrows are blown by
the natives of Guiana. In the island of Celebes the only article of
dress worn by the natives is a body-cloth called Kian Pakkian, made
of bamboo split into fine shreds, which are passed between the teeth
and bitten until they are soft, when they are woven.
If, after providing himself with these and similar necessaries, our
shipwrecked man found leisure to amuse himself, he might make æolian
flutes, such as Sir Emerson Tennant saw in Malacca, by boring holes
in the stems of living bamboos, or he might construct a harp like
that in the Kew Museum, London, which was brought from Timor by Mr.
Wallace. This harp is made from a cylinder of bamboo having a node
at each end. Under a strip of the outer rind a quarter of an inch
wide, a sharp knife is passed so that the strip is detached from
the cylinder except at its two ends. The strip forms one of the
harp strings. Two small wedges are pushed under it, and the portion
between the wedges can be sounded like the string of a guitar. It
is also possible, and not very difficult, to make such diverse
articles as paper, pens, waterproof clothing, hats, wax, pickles,
bird-whistles, rafts, pillows, fermented drink, and bridges from the
same versatile vegetable. In the Kew Museum, which should be visited
by every one who wishes to see the varied uses to which bamboos
can be applied, perhaps the most curious article is a headman’s
knife brought by Mr. Franks from the southeastern peninsula of New
Guinea. This singular implement, which is shaped like a cheese-scoop
and seems very ill-adapted to its purpose, is marked with numerous
notches, each notch representing one of its victims; and it is
accompanied by an artistic apparatus, also of bamboo, intended
apparently to enable the executioner to carry the severed head.
The bamboo usually grows in a cluster of from ten to a hundred
stalks, and springing from the same rhizome or root-stock. The
rhizome is not the root, but an underground portion of the stem. It
consists of a number of segments about the size and shape of a banana
and somewhat bloated in the middle. The banana-like segments are
joined together irregularly by their tips, so that the whole rhizome
forms a strong underground trellis-work admirably adapted to support
the light and yet rigid stems that rise up from it. From the under
side of the rhizome spring downward the true root-fibres, numerous as
the bristles of a broom.
The stem itself, as every one knows, is smooth, polished, and
cylindrical, and is divided into air-tight compartments by knots or
nodes, which are the points at which the fibres of the stem cross
over from one side to the other. The lowest ten nodes or so are
usually bare, but from the upper nodes issue branches. These are very
slender as compared with the main stem, and carry the foliage leaves.
In most species the leaves are rather small, but in some they are
very large. The species named Planotia nobilis by General Munro, a
native of New Granada, has the largest leaves of any kind of grass;
they are often a foot in diameter and fifteen feet in length.
The most important part of the bamboo, from a botanical point of
view, is the flower, which roughly resembles the flower of our
common grasses. The flower of grass is inclosed in hard, scaly
leaflets called glumes; it usually has three stamens and one
seed-vessel. There may be only one flower inclosed in the glumes
(as in foxtail grass), or more (as in wheat). The flowers of the
bamboos, while on the whole conforming to the grass type, exhibit
many small differences in different species. In some kinds, as in
Arthrostylidium longiflorum, the inflorescence resembles a bunch of
ears of wheat; in others, as in Bambusa vulgaris, the flowers are
packed into round clusters; in others, as in Chusquea simpliciflora,
they are in threes and fours, each flower hanging by a separate
slender stalk. The seed generally resembles oats or wheat, but in
some species it takes the form of a berry, not unlike the seed of our
familiar pimpernels. In the species known as Molocanna, the fruit is
exceptionally developed, often attaining the size of a largish pear.
Some species flower and die down annually; others flower annually,
but live on; as a rule the bamboo grows for many years without
flowering, and then suddenly bursts into bloom. From the fact that
the number of years between the sowing of the seed and the flowering
of the plant varies, and that in some years nearly all the bamboos
in a given district flower simultaneously, it would seem as if the
blossoming does not take place at any prescribed age, but may occur
at any period after the plants reach maturity when a favorable season
supervenes. It used to be thought that after a general flowering of
the bamboos throughout a district all the plants died, but this view
proves to be incorrect. The flowering shoots usually die, and during
the flowering the foliage almost entirely disappears, but the entire
plant is not necessarily killed.
The Chinese have a proverb that the bamboo produces seed most
abundantly in years when the rice crop fails, and several curious
cases of the truth of this saying have been recorded. According to
General Munro, in 1812 the universal flowering in Orissa prevented a
famine. Hundreds of people, he says, were on the watch day and night
to secure the seeds as they fell from the branches. Another instance
occurred in 1864, when there was a general flowering of the bamboo in
the Soopa jungles, and very large numbers of persons came from the
neighboring districts to collect the seeds.
In most bamboos, the stem is characterized by straightness,
smoothness, roundness, and quickness of growth, no doubt because
these qualities have, as a rule, proved serviceable to the plant in
the struggle for existence. Light and air being necessary to the life
of grass, it is manifest that in the dense vegetation of the tropics
a plant which can push itself rapidly to a great height must have an
advantage; and in order that growth may be rapid and the plant spring
up to a considerable height without climbing, it is essential that
there should be as little material as possible in the stem, and yet
that it should be as strong as possible. It is difficult to imagine a
stem in which these conditions would be better fulfilled than in that
of the bamboo. By reason of its hollowness the amount of material
is reduced to a minimum; and by reason of its cylindrical shape,
its nodes, and the hardness of the outer rind, the strength of the
structure is at a maximum. The growth is consequently very rapid, an
increase in height of 2 to 2½ feet having been recorded in a single
day. The Bambusa Brandisii often measures as many as 120 feet, and is
said to attain its full altitude in a few months.
But although, as a general rule, the necessities of natural selection
have ordained that bamboos shall be perfectly straight and perfectly
round, this archetypal form or idea (to borrow a word from Plato)
does not always hold good. One species, found in Asia, is said to
have crooked and even creeping stems. Another, found in Ecuador,
is described by General Munro as being distinctly a climbing plant.
There is a species, recently described by Mr. Thiselton Dyer, with a
stem exactly square, and as well defined as if cut with a knife. It
has only lately been found in China, where it is grown chiefly for
ornament.
According to Mr. Dyer, the Chinese account for its squareness in the
following way. They say that in the Fourth Century A. D., the famous
alchemist, Ko Hung, took his chopsticks (which consist of slender
rods of bamboo pared square) and thrust them into the ground of the
spiritual monastery near Mingpo; and then by his thaumaturgical art
he caused them to take root and appear as a new variety--the square
bamboo.
The growth of plants is one of the greatest mysteries of nature, and
nothing is more mysterious in their growth than their limited but
very definite power of movement. How is it that some plants grow
vertically upward, like the normal bamboo, others climb and twist,
others creep, and others grow in zigzag shapes? How is it that some
turn toward the light, some away from the light, while others place
themselves at right angles to it? And how is it that if you peg down
the young stem of a vertically growing plant it will bend upward
beyond the peg? No doubt the proximate cause is natural selection;
they do these things because they have found them advantageous. But
this does not tell us by what mechanism a plant is enabled to keep
on growing in the particular direction which it finds advantageous.
We know that when a plant bends in a given direction, the cells
on the convex side of the bend are more turgescent, that is, more
distended with sap, than those on the concave side, and that the
increased turgescence of the former is followed by increased rapidity
of growth; but what causes the distribution of turgescence in the
cells has not been clearly made out. It seems probable, however,
that when a shoot is growing in its proper and natural direction,
the chief force which guides it and enables it to maintain that
direction is the force of gravitation. To this force the growing
portions of a plant are extremely sensitive. Consider, for example,
the case of a vertically growing shoot. Whenever it is accidentally
bent the force of gravity must evidently act upon the portion above
the bend, tending to curve it still more, and causing a strain in
the material of the stem. The plant in some mysterious way is aware
of this strain, and the cells of the lower side of the bent portion
are stimulated to increased turgescence as compared with those of
the upper side, so that the under side would grow faster; and as
the plant would turn upward in consequence, any deviation from
the perpendicular would tend to correct itself. Similarly a shoot
which grows horizontally is led by the same stimulus of gravitation
to rectify any departure from a horizontal position. Gravitation,
then, does not _cause_ the bending when a displaced shoot endeavors
to regain its normal direction, but serves merely as a guide. By
its means the plant is made aware (so to speak) that it has been
displaced, and takes measures accordingly. If the force of gravity
were absent, the shoot would go on growing in any position in which
it might happen to be placed. This may be proved by causing a growing
seed to revolve slowly round a horizontal axis, so that at every
revolution the force of gravity may act upon it equally in all
directions. When a shoot is grown in these conditions, it is found
that its power of correcting deviations from any particular line of
growth is lost. Similar reasoning applies to the action of light on
plants, but, as above stated, we do not know why it is that plants
respond to the stimulus of light or gravity; we only know that as a
matter of fact they do so.
It has often been vaguely asserted that plants are distinguished from
animals by not having the power of movement. It should rather be said
that plants acquire and display this power only when it is of some
advantage to them; but that this is of comparatively rare occurrence,
as they are affixed to the ground, and food is brought to them by the
wind and rain. We see how high in the scale of organization the plant
may rise when we look at one of the more perfect tendril-bearers.
It first places its tendrils ready for action, as a polypus places
its tentacula. If the tendril be displaced, it is acted on by the
force of gravity and rights itself. It is acted on by the light, and
bends toward or from it, or disregards it, whichever may be most
advantageous. During several days, the tendril or internodes, or
both, spontaneously revolve with a steady motion. The tendril strikes
some object, and quickly curls round and firmly grasps it. In the
course of some hours it contracts into a spire, dragging up the stem
and forming an excellent spring. All movements now cease. By growth
the tissues soon become wonderfully strong and durable. The tendril
has done its work, and done it in an admirable manner.
THE REIGN OF EVERGREENS
--GRANT ALLEN
The poor stripped and draggled garden is beginning to look very bare
now (November) of all except a few straggling late-flowering shrubs
and those trusty adopted friends that we have always with us, the
shrubby, large-leaved southern evergreens. In northern climates,
we must ruefully admit, there are hardly any true evergreens, save
only the conifers, with their stiff and needle-like foliage, such
as pines and spruce-firs; but we make up for it to some extent by
borrowing from warmer or more southern lands the laurels, aucubas,
laurustinuses and rhododendrons, that help to keep bright our
English lawns and shrubberies throughout the long and weary winter
months. Indeed, our only native flat-leaved shrubs that retain their
full greenness from year’s end to year’s end are privet, box, and
butcher’s broom, all three of them very doubtfully indigenous to
these islands. It is the rule with English trees and shrubs to shed
their foliage every autumn; and the fashion in which they do so shows
very clearly how purposive and well adapted to their conditions in
life is the deciduous habit. For the leaves do not merely tumble
off anyhow, casually, before the first fierce autumnal winds; if
they did so there would be loss of sap and of valuable foodstuffs to
the whole plant of whose joint commonwealth they form the partially
dependent members: their fall is duly provided for beforehand, and
when at last it actually takes place, it takes place in an orderly
and regular fashion, with the least possible injury to the interests
of the entire tree. From the very beginning there has been arranged
at the joint where the leaf-stalk joins the stem, or where the
separate leaflets join the central midrib, a row or articulation
composed of cellular tissue, and specially designed to act as a joint
for the dry leaves. When winter approaches, and chilly northern
winds are likely to tear to pieces the leaves on the trees, all the
protoplasm and other valuable cell-contents are withdrawn into the
permanent tissues of the plant, leaving only the minor red and yellow
coloring matters (mostly effete and used-up foodstuffs) which give so
much beauty and glory to the general aspect of our autumn woodlands.
Then the articulation dries up and withers, and the dead leaf
separates at the joint, leaving behind it a regular mark or scar,
which is the visible token of Nature’s definite precaution against
the northern cold and tempests.
It was not always so, however, and it is not so even now in the
greater part of the modern world that we ourselves inhabit. It
seems quite natural to us northerners that “leaves have their time
to fall”; so natural, indeed, that we almost forget the strict
limitation of the practice to our own chillier latitudes. Yet in
reality the existence of deciduous trees is a mere temporary accident
of the here and the now, a passing consequence of the great cold
spell which had its culminating point in the last glacial epoch, and
from whose lasting effects we ourselves are even still apparently
suffering. Whether, as Mr. Alfred Russel Wallace seems hopeful enough
to believe, our poor old planet may yet recover from this premonitory
chilling or not, whether we may yet look forward to a few more
warm spells or otherwise, before the final numbness of all dying
worlds comes upon us, is a question rather for the consideration of
astronomers and physicists than the mere mundane-roving naturalist,
with his petty ephemeral interests in our plants and animals; but
one thing at least is certain, that till a very recent period,
geologically speaking, our earth enjoyed a warm and genial climate up
to the poles themselves, and that all its vegetation was everywhere
evergreen, of much the same type as that which now prevails in the
modern tropics. Indeed, we have only to look at the existing state of
things in order to see how very slight is the effect that has thus
been produced upon our temperate flora. For example, among the oaks
alone, there are some twenty species in Europe, of which Southern
Europe has eighteen, mostly evergreen, while north of the Alps there
are only two, or at most three, all of them deciduous. From the
evolutionary point of view it is clear that the northern kinds are
modern developments, specialized to contend with the peculiarly cold
conditions of sub-Arctic Europe.
Fortunately, too, we are not left in this matter to mere conjecture
or analogy: thanks to the researches of Heer and others, we have
positive geological facts to guide us which show conclusively that up
to the Miocene period Europe was covered by forests of large-leaved
evergreen trees, of what we should now consider distinctively
tropical types. Ever since the Miocene, and on to the culminating
point of the great Ice Age, the European climate has been growing
steadily colder, and the European flora has been at the same time
steadily adapting itself to the new conditions, and to assuming
what we now consider a typically northern aspect. During all that
time, the large-leaved evergreens gave way before the deciduous
trees and the chillier conifers, beginning at the north pole and
spreading gradually southward, as the cold deepened and widened
its range. Since the end of the great Ice Age, and the subsequent
slight amelioration of the climate in Northern Europe, a reverse
process has begun to set in; the Arctic types have begun to recede
slightly once more, and the comparatively southern or temperate
types have pushed their way northward to occupy the place from which
they were previously dispossessed by the newly evolved kinds. It is
not necessary for us to inquire here into the causes of this great
cycle; the facts are there, and for our present purpose they are
quite sufficient. They show conclusively, when one follows them out
in detail, that the evolution of deciduous trees was concomitant with
the growth of cold conditions around the two poles; and that such
trees now exist only where winter, for part of the year, renders the
evergreen condition an undesirable one. Even in the tropics, indeed,
we find on high mountains a belt of deciduous forest, stretching
above the belt of large-leaved evergreens, which itself succeeds to
the lowland palms and tree-ferns of the thorough-going equatorial
plains.