the horse-chestnut is to be found in the fact that they are both
_nuts_--they have survived in the struggle for existence by adopting
for their seed-vessels the exactly opposite tactics from those
adopted by the true fruits. A fruit, as we have often seen, is a
seed-vessel which lays itself out, by all the allurements of bright
color, sweet scent, sugary juices, and nutritive properties, to
attract animals who will aid it by swallowing it, and so eventually
dispersing its seeds. But a nut is a seed-vessel which, on the
contrary, being richly supplied with starches and oils for the supply
of the young plantlet, would be injured and diverted from its real
intent and purport if it were to be eaten and digested by any animal.
Accordingly, nuts have concentrated all their efforts upon repelling
rather than attracting the attention of animals; or, to put it in
a more strictly physical way, those nuts which have happened to
be least attractive in color and most protected by hairs, spines,
prickles, or bitter juices have best succeeded in escaping the
attacks of animals, and so have prospered best in the struggle for
existence. Thus, to drop into metaphor once more, while the fruits
want to be eaten, the nut, on the contrary, wants to escape.
We may take the chestnut as a very good example of the general result
which the necessity for protection usually produces in these peculiar
seed-vessels. While it still grows on the tree the entire fruit
is green and unobtrusive, hardly noticeable at a little distance
among the heavy foliage which covers it on every side. Compare this
shrinking and secretive habit with the brilliancy and vividness of
oranges and mangoes, or even with our own bright-colored northern
rose-hips, and haws, and mountain ashes, and holly-berries. Again,
instead of being smooth skinned and soft, like these bird-enticing
fruits, the outer rind of the chestnut is rough and repellent
with serried prickles, which rudely wound the tender nose of the
too inquisitive squirrel, or even the feathery cheeks of the more
protected nut-hatch. Once more, when the separate nuts inside have
fallen out upon the ground, they are no longer green like the foliage
upon the tree, but light brown or “chestnut,” like the dead leaves
and withered bracken into whose midst they have gently fallen.
Chestnuts themselves are apparently sufficiently protected by these
devices of color and prickliness; they do not seem further to require
the special nut-like covering of a hard and woody shell; but the
filbert, which suffers far more from the depredations of dormice,
squirrels, nut-hatches, and other birds or mammals, has not only
incased itself without in a green husk covered by sharp and annoying
little hairs, but has also acquired a very solid and difficult shell,
which often succeeds in baffling even the keen teeth or beaks of its
persistent and aggressive animal foes.
Indeed, even among British nuts, one may trace a regular gradation
(not, of course, genealogical) from the softest and least protected
to the hardest and most defensive kinds. The acorn, produced in vast
numbers by a very large and long-lived tree, the oak, has hardly
any need of a strong outer coat of armor, especially as its kernel
is rather bitter and far from attractive to most animals, though it
still feeds a considerable legion of hoarding squirrels, and must
once have been munched in immense quantities by the native wild
boars, or their mediæval successors, the half-tamed forest swine. In
the beech, the shell of the actual nut itself is merely leathery;
but the outer coat or involucre is sprinkled over with distinctly
protective prickles. (It is worth while to note in passing that the
beechnuts or mast rarely contain a kernel in Britain--in other words,
they are almost always sterile; whereas in other countries where the
beeches are more sturdy, the nuts are usually fertile; and this fact
may be put side by side with the corelative fact that the beech is
a decadent tree in England, where it was once dominant, but is now
rapidly dying out before our very eyes, at least in its indigenous
form.) In the lime, the very small nut has a decided shell, while
its globular shape also makes it difficult for quadrupeds to open
with their paws and teeth. Finally, in the hazel, the filbert has a
very hard integument indeed, and a disagreeable, husky covering of
smarting hairs.
Our own English nuts are only exposed to the attacks of extremely
small and comparatively harmless mammals, or of inconsiderable native
birds; and, therefore, their defensive tactics have never been
carried any further than in the case of the hedgerow filbert. But in
southern climates, and especially in the tropics, nuts are exposed
to far larger and more dangerous forestine foes, like the monkeys
and parrots, against whose teeth or bills, as we all know, even
the solid shell of the Barcelona cob is absolutely no protection.
Hence, under these circumstances, only the very hardest or most
disagreeable nuts have been able to survive and to grow up in due
time into flourishing nut-trees. Sometimes, as in the walnut, the
chief protection is afforded by a nauseous outer rind--a system which
reaches its climax in the South American cashews, whose pungent juice
blisters the skin like a cantharides plaster; sometimes, as in the
cocoanut, it is afforded by great thickness and hardness of shell,
which sets at naught the most persistent endeavors of the hungry
aggressor. In the Brazil nut, a number of sharp, angular nuts are
crowded together inside a large and hard outside shell, so that even
after the monkey has managed to crack the big outer nut, he has still
to open all the inside nuts one by one in detail. It is worth while
to notice, too, that an exactly similar modification is undergone in
the tropics by the stones of stone-fruits; which are really nuts in
disguise, covered only by a soft, sweet pulp that entices animals
to aid in dispersing them, by dropping the hard seed on to the
ground in favorable spots for its growth. In temperate climates the
stones are only hard enough to defy squirrels and birds: in tropical
countries they are hard enough to defy monkeys and parrots. Compare,
for example, the English sloe or bird-cherry with the peach-stone,
and the English haw with the mango or vegetable ivory. This last nut
is one of the oddest in the whole range of nature, for it is here
the actual kernel itself that grows so hard and horny. Yet even the
vegetable ivory, which consists really of very solid starchy cells,
softens and yields up its material to the growing plant as soon as
the embryo it incloses begins to sprout under the influence of warmth
and moisture.
THE CACTUS TRIBE
--M. J. SCHLEIDEN
Let us leave the forest of Guiana, the last mat-roof of the Guaranese
between the trunks of the Mauritius palm, and enter the pampas of
Venezuela, of which Humboldt has sketched such a clever and vivid
picture. No smiling verdure clothes the glowing rock-soil here;
here and there in its crevices the Melocactus displays its round
balls, “horrid” with threatening thorns. Ascend we thence the Andes;
instead of tender grass, the earth is covered with pale, gray-green
globes of spiny Mamillarias, while, intermingled, rises the solemn
and mournful old-man cactus, with its venerable-looking long gray
hair. Borne on the wings of fancy further north, we descend into
the plains of Mexico, where the gigantic fragments of the city of
the Aztecs, a product of a solitary era of civilization long lost
to history, display themselves; the landscape spreads out before us
as the bare and naked Tierra caliente, parched by the glowing sun;
of a dull green hue, without a branch or leaf, the angled-columns
of the torch-thistles rise twenty or thirty feet high, hemmed in
with an impenetrable thicket of irritably pricking Indian figs,
while round about appear the strangest, ugliest forms, in the
groups of the Echinocacti and little Cerei, between which creeps
snake-like, or as some great poisonous reptile, the long, dry stem
of the great flowered cactus (Cereus nycticallus). In short, one
family accompanies us through all our wanderings, that of the cactus
plants, which seems in all its wondrous forms to withdraw itself
entirely from the principle of beauty, and yet at the same time
presses forward so strikingly, so determinately marking the peculiar
character of the landscape, that we are compelled to turn our
attention to it. And in truth, a group which appears to retreat so
far from all the laws of other plants deserves our interest in a very
high degree.
Everything about these plants is wonderful. With the exception of
the genus Peireskia, no plant of the order possesses leaves. Those
parts of Cactus alatus, and the Indian fig, which are commonly called
leaves, are nothing but flattened expansions of the stem. On the
other hand, they are all distinguished by an extraordinarily fleshy
stem, which, clothed by a grayish-green, leathery cuticle, and
beset, in the places where leaves are situated in regular plants,
with various tufts of hair, spines, and points, gives by its very
varied degrees of development the varied character of the plants. The
torch-thistles rise in form of nine-angled or often round columns to
a height of thirty or forty feet, mostly branchless, but sometimes
ramifying in the strangest ways, and looking like candelabra; the
Indian figs are more humble; their oval, flat branches, arranged
upon one another on all sides, produce special forms. The lowest
and thickest torch-thistles connect themselves with hedgehog and
melon-cacti, with their projecting ribs, and thus lead us to the
almost perfectly globular Mamillarias, which are covered very
regularly with fleshy warts of various heights. Finally, there are
forms in which the growth in the longitudinal direction prevails,
which with long, thin, often whip-like stems, like those of the
serpent-cactus, hang down from the trees upon which they live as
parasites.
Few families have so limited a range of distribution upon the globe.
All the species of cactus, perhaps without a single exception, are
indigenous in America, between the parallels of 40° S. lat. and 40°
N. lat. But some of them were so rapidly distributed through the
Old World directly after the discovery of America, that they may
almost be looked upon as fully naturalized there. Almost all delight
in a dry situation, exposed to the burning rays of the sun, which
contrasts strangely with their fleshy tissue, tumid with watery and
not unpleasantly flavored with acid juice. This peculiarity gives
them inestimable value to the fainting traveler, and Bernardin de
St. Pierre has aptly called them the “Springs of the Desert.” The
wild ass of the llanos, too, knows well how to avail himself of
these plants. In the dry season, when all animal life flees from the
glowing pampas, when cayman and boa sink into death-like sleep in
the dried-up mud, the wild ass alone, traversing the steppe, knows
how to guard against thirst; cautiously stripping off the dangerous
spines of the Melocactus with his hoof, and then in safety sucking
the cooling vegetable juice. In vertical extension, the cacti are
not confined within such narrow limits, and they stretch from the
lowest tracts along the coast, through the vast plains, up to the
highest ridges of the Andes chain. On the shore of Lake Titicaca,
12,700 feet above the level of the sea, are seen the tall-stemmed
Peireskias with their splendid deep brown-red blossoms, and on the
plateaus of southern Peru, near the limit of vegetation, therefore
about 14,000 feet high, the wanderer is surprised by peculiar shapes
of a yellowish-red color, which at a distance look like reposing
savages, but which a closer inspection reveals to be shapeless heaps
of low cacti, closely beset with yellowish-red spines.
What Nature has withheld, however, in external aspect, she has, in
most, richly replaced in the magnificent blossom. We are astonished
to find the deformed gray-green mass of the Mamillaria decked with
the most beautiful purple-red flowers. Strange is the contrast
between the wretched and gloomy aspect of the naked, dry stem of
the large-flowered torch-thistle (Cereus grandiflorus), and its
large, splendid, Isabel-colored,[8] vanilla-scented, flowers, which,
unfolding under cover of the silent night, beam like suns, and in the
wonderful sporting of their stamens, seem almost to strive toward a
higher--an animal life.
But it is not the beauty of the blossom alone which gladdens us,
not the refreshing sap alone that revives the languishing traveler.
The economic uses are also manifold. Almost all the cacti bear
edible fruit, and a portion of them are among the most delightful
refreshments of the hot zones which ripen them. Almost all the
Opuntias, known by the name of Indian figs, furnish, in the West
Indies and Mexico, a favorite dessert fruit, and even the little
rose-red berries of the Mamillarias, which with us are tasteless,
have, beneath the tropics, a pleasant, acidulated, sweet juice. We
may say, in general terms, that their fruit is a nobler form of our
native gooseberry and currant, to which also they are the nearest
allies in a botanical point of view. Succulent as is the stem of
most of the cacti, yet, in the course of time, they perfect in it
a wood as firm as it is light. This is especially the case in the
tall columnar species of cereus, the old dead stems of which, after
the decay of the gray-green rind, remain erect, their white wood
standing ghost-like among the living stems, till a benighted traveler
seizes it in that scantily wooded region, to make a fire to protect
him from the mosquitoes, to bake his maize-cake, or burns it as a
torch to light up the dark tropical night. It is from the last use
that they have obtained the name of torch-thistles. These stems, on
account of their lightness, are carried up on mules to the heights
of the Cordilleras, to serve as beams, posts, and door-sills in the
houses; as, for instance, in the mayoral of Antisana, perhaps the
highest inhabited spot in the world (12,604 feet). Just as their
allies, the gooseberry bushes, are used by our country people to
form hedges to their gardens, are the Opuntias in Mexico, on the
west coast of South America and in the southern part of Europe, and
with greater success in the Canaries; their firm, shapeless branches
soon interweave themselves into an impenetrable barrier, opposing,
by their dreadful spines, an insuperable obstacle to the intruder.
Lastly, the medicine-chest does not go away empty, for the physicians
of America make abundant use of the acid juice for fomentations in
inflammations, not to mention some other prescriptions.
In the same way that grass and clover are not immediately valuable
to man, but serve as food for useful animals, so it is with a number
of cacti, which support an insect of extraordinary importance. This
is the cochineal insect (Coccus Cacti), a little, very insignificant
creature, externally just like the little, white, cottony parasite,
which is so often found upon the plants in our hothouses, and yet,
through the invaluable coloring matter it contains, so infinitely
different from it.
While the ugly form, the splendor of the blossom, and the manifold
uses of the cactus plants attract general interest in a high
degree, they are not less interesting, in a narrower sphere, to the
botanist. Zoologists have at all times found in the examination of
monstrosities and aberrant forms rich material toward the clearing
and expanding of their knowledge of the regularly developing
organism. It is to be expected, therefore, that similar conditions
will have similar value in the vegetable world; and what family could
be better selected for this purpose than the Cactaceæ, which seems
to be but a natural museum of monstrosities, where the forms are, in
some cases, so abnormal that no other name could be thought of for
one species but that of the deformed cactus (Cereus monstrosus)?
It is believed that from the vast amount of watery juice in the
cactus tribe, joined to the fact that most of them, and exactly
those richest in sap, vegetate on dry sand, almost wholly devoid of
vegetable mould, where they are besides exposed often three-fourths
of the year to the parching sunbeams of an eternally serene sky; from
this combination of circumstances, even, it is thought that we may
the more safely conclude that these plants draw their nourishment
from the air, since in our own hothouses also it has been observed
that the branches of cactus stems cut off and left forgotten in a
corner without further care, far from dying, have frequently grown on
and made shoots three feet long or more. De Candolle first found the
right path when he weighed such cactus shoots which had grown without
soil, and found that the plant, though larger, was always lighter,
therefore, instead of abstracting anything from the atmosphere, must
rather have given up something to it. All the growth takes place,
in such cases, at the expense of the nutritive matter previously
accumulated in the juicy tissue, and it generally exhausts the plant
to such a degree that it is no longer worth preserving. It is that
succulent tissue which enables the cactus plants--one might compare
them with the camels--to provide themselves beforehand with fluid,
and thus to brave the rainless season. Their anatomical structure
also assists them in this respect in a peculiar manner. We know from
the experiments of Hales that plants chiefly evaporate the water
they contain through their leaves, and the cactus tribe have none.
Their stem, too, unlike that of all other plants, is clothed with a
peculiar leathery membrane, which wholly prevents evaporation. This
membrane is composed of very strange, almost cartilaginous, cells,
the walls of which are often traversed by elegant little canals.
Its thickness varies in different species, and it is thickest, and
therefore most impenetrable, in the Melocacti, which grow in the
driest and hottest regions, while it is least remarkable in the
species of Rhipsalis, which are parasites on the trees of the damp
Brazilian forests.
Another striking point about this group is the formation of an
extraordinary quantity of oxalic acid. If this acid were collected
in large amount in the plant, it must necessarily be dead to it.
The plant, therefore, takes up from the soil on which it grows a
proportionate quantity of lime, which combines with the oxalic acid,
forming insoluble crystals, which occur in abundance in all the
Cactaceæ.
A third peculiarity is exhibited in the globular forms of Melocactus
and Mamillaria, in the structure of the wood, which differs entirely
from that of the common ligneous plants. Common wood, for example
that of the poplar, is composed of long _wood-cells_, the walls of
which are quite simple and uniform, and of cells containing air,
the so-called _vessels_, the walls of which are very thickly beset
with little pores. Wholly unlike this, the wood of the cactus,
above-mentioned, exhibits only short, spindle-shaped cells, inside
which wind most elegant spiral bands, looking like little spiral
staircases.
Lastly, the hair, spines, etc., situated in the places of leaves,
deserve a special mention. Generally speaking, three forms may be
distinguished, all three usually occurring together on the same
spot. The first are very flexible, simple hairs, which form a
little flat, soft cushion; among these is found a bunch of longish
but thin spines. These it is chiefly which, on account of their
peculiar structure, make the careless handling of the cactus plants
so dangerous. These little spines are very thin and brittle, so that
they readily break off, and are covered with barbed hooks directed
backward from the point. When touched, a whole bunch penetrate the
skin; if an attempt is made to draw them out, the separate spines
break in the skin, and the fragments pierce in other places; when the
hand is drawn over them, they catch in, and an insufferable itching,
terminating in a slight inflammation, spreads over all the parts
which have been touched. The Opuntia ferox is especially remarkable
for these spines, whence its name, the _savage_. Among the hairs and
smaller spines arise very long and thick spines, in different form
and number, which give the best characters for the determination of
the species. In some these are so hard and strong that they even lame
the wild asses which incautiously wound themselves, when kicking off
the spines to reach the means to still their thirst. In Opuntia Tuna,
which is the kind most frequently used for hedges, they are so large
that even the buffaloes are killed by the inflammation following from
these spines running into their breasts.
FUNGI
--HUGH MACMILLAN
Fungi are intimately associated with autumn; unrobed prophets that
see no sad visions themselves, but that bring to us thoughts of
change and decay. Indeed, so close is this association that they may
be called autumn’s peculiar plants. The bluebell still lingers on
the wayside bank, and in the woods a few bright but evanescent and
scentless flowers appear, but fungi and fruits form the wreath that
encircles the sober and melancholy brow of autumn: fruits, the death
of flower-life; fungi, the resurrection of plant-death. The seasonal
conditions which arrest the further progress of all other vegetation,
which cause the leaf to fall, and the flower to wither, and the robe
of nature everywhere to change and fade, give birth to new forms of
plant-life which flourish amid decay and death. From the relics of
the former creations of spring and summer reduced to chaos, springs
up a new creation of organic life; and thus nature is not a mere
continuous cycle of birth, maturity, and decay, but rather a constant
appearance of old elements in new forms.
In many respects they are the most mysterious and paradoxical of
all plants. In their origin, their shapes, their composition, their
rapidity of growth, the brevity of their existence, their modes of
reproduction, their inconceivable number and apparent ubiquity, they
are widely different from every other kind of vegetation with which
we are acquainted. In studying their history we walk amid surprises;
and as we lift each corner of the veil, more and more marvelous are
the vistas that reveal themselves.
The first thing that suggests remark in regard to these curious
organisms is their origin. Incapable of deriving the elements of
growth from the crude unorganized crust of the earth, they are
parasitical upon organic bodies, and are sustained by animal and
vegetable substances in a state of decomposition. That living and
often nutritious objects should spring from festering masses of
corruption and decay; that plants, endowed with all the organs
and capacities of life, should start into existence from the dead
tree that crumbles into dust at the slightest touch, or draw their
nourishment from dried and exhausted animal excretions, which have
lain for months under the influence of drenching rains and scorching
sunbeams, is indeed a profound mystery of nature. No sooner does the
majestic oak yield to the universal law of death, than several minute
existences, which had been previously bound up and hid within its
own, reveal themselves, seize upon the body with their tiny fangs,
fatten and revel upon its decaying tissues, and in a short space of
time reduce the patriarch and pride of the forest, which had braved
the storms of a thousand years, into a hideous mass of touchwood, or
into a heap of black dust. How strikingly do these plants illustrate
the great fact, that in nature nothing perishes; that in the
wonderful metamorphoses continually going on in the universe there
is change, but not loss; that there is no such thing as death, the
extinction of one form of existence being only the birth of another,
each grave being a cradle.