CHAP. XXXIII.

Previous

CURIOSITIES RESPECTING VEGETABLES.

Curiosities in the Vegetable Kingdom—Germination of Seeds—Dissemination of Plants—Number of Plants upon the Earth—Sensibility of Plants—The Sensitive Plant.

Your contemplation further yet pursue;
The wondrous world of vegetables view!
See various trees their various fruits produce,
Some for delightful taste, and some for use.
See sprouting plants enrich the plain and wood,
For physic some, and some design’d for food.
See fragrant flow’rs, with different colours dy’d,
On smiling meads unfold their gaudy pride.
Blackmore.

Curiosities In The Vegetable Kingdom.

The difference between animals and vegetables is so great, that at first we do not perceive any resemblance between them. Some animals only live in water; others on the earth, or in the air; and some are amphibious, or live equally well in water as upon land. And this is literally the case with vegetables: some of them only grow upon land, others in the water; some can scarcely bear any moisture, others live either in earth or water; and some even are found that exist in the air.

There is a tree in the island of Japan, which, contrary to the nature of all others, to which moisture is necessary, cannot bear the least portion. As soon as it is watered it perishes: the only way to preserve it in such a case, is to cut it off by the root, which is to be dried in the sun, and afterwards planted in a dry and sandy soil. A peculiar species of mushroom, some mosses, and other small plants, float in the air; but what is still more extraordinary, a branch of rosemary, which, as is the custom of some countries, was put in the hand of a corpse, sprouted out to the right and left so vigorously, that after a lapse of some years, the grave being opened, the face of the defunct was overshadowed with rosemary leaves. The vegetation of the truffle is still more singular: this extraordinary tubercle has neither roots, stem, leaves, flowers, nor seeds; it derives its nourishment through the pores of its bark. But it may be asked, how is it produced? why is there commonly no kind of herb in the places where this species of fungus grows? and why is the land there dry and full of crevices? These things have never been explained. No plant so much resembles animals, as that species of membranous moss called nostoch; it is an irregular substance, of a pale green colour, and somewhat transparent; it trembles upon the slightest touch, and easily breaks. It can only be seen after rain, and is then found in many places, particularly in uncultivated soils and sandy roads. It exists in all seasons, even in winter; but is never so abundant as after rain in summer. The most remarkable circumstance about it is, its speedy growth, being formed almost instantaneously: sometimes walking in the garden in summer, not a trace of it is seen, when a sudden shower of rain falling, if the same place is visited in an hour, the walks are entirely covered with it. The nostoch was long supposed to have descended from the sky; but it is now known to be a leaf, which attracts and imbibes water with great avidity. This leaf, to which no root appears to belong, is in its natural state when impregnated with water; but a strong wind or great heat soon dissipating the water, the leaf contracts, and loses its colour and transparency: hence it appears to grow so suddenly, and to be so miraculously produced by a shower of rain; for when the rain falls upon it in its dried and imperceptible state, it becomes reanimated, and appears a fresh production.

We might readily enumerate a variety of plants that bear a resemblance to animals; but there are other peculiarities in vegetables, which solicit our attention. The whole atmosphere is pregnant with plants and invisible seeds, and even the largest grains are dispersed by the wind over the earth; and as soon as they are transported to the places where they may germinate, they become plants, and often so little soil is necessary for this purpose, that we can scarcely conceive whence they derive the necessary degree of nourishment. There are plants, and even trees, which take root and grow in the clefts of rocks, without any soil. Vegetation is sometimes very rapid; of which we have instances in mushrooms, and the common cresses, the seed of which, if put into a wet cloth, will be fit for a salad in twenty-four hours. There are plants that exist with scarcely any perceptible vitality. We often see willows, which are not only hollowed and decayed within, but their external bark is so much injured that very little of it remains; yet from these seemingly sapless trunks, buds sprout in the spring, and they are crowned with leaves and branches. How admirable, that plants should not only imbibe nutriment by their roots, but that their leaves also should assist in this important function, by inspiring air! and an inverted tree will flourish as well as when in its proper position, for the branches will grow in the earth and become roots! The advanced age that some trees attain, is also very wonderful. Some apple-trees are above a thousand years old; and if we calculate the amount of the annual produce of such a tree for the above space of time, we shall find that a single pippin might supply all Europe with trees and fruit.

The Germination of Seeds.—Seeds are composed of different parts, according to the variety of species, the principal of which parts is the germ. Each germ has two parts: the one simple, which becomes the root; and the other laminated, which becomes the stem of the plant. The substance of most seeds is composed of two pieces, called lobes, which contain a farinaceous matter, and serve as seminal leaves to the plants. Mosses have the most simple seed, consisting only of the germ, without pellicle, and without lobes. To make seeds germinate, air, and a certain degree of heat and moisture, are necessary. The augmented heat, and the difference observable in the taste and smell, seem to denote a degree of fermentation; and the farinaceous substance becomes fitted to nourish the tender germ. It has been ascertained by experiments made with coloured fluids, that this substance imbibes a moisture, which, in conjunction with the air and heat, forms a proper nourishment till the plant has acquired strength enough to make use of the juices furnished by the root. The lobes, exhausted of their farinaceous matter, gradually dry, and fall off of themselves in a few weeks, when the plant has no further need of their assistance.—Certain herbs which grow on the mountains are of a very peculiar nature: their duration being very short, it often happens that the seed has not time to ripen; and, that the species may not be lost, the bud which contains the germ is formed upon the top of the plant, puts forth leaves, falls, and takes root. When the delicate plant shoots up from the earth, it would run too great a risk, if it were immediately exposed to the air, and to the influence of the sun. Its parts therefore remain folded close to each other, nearly the same as when in the seed. But as the root grows strong and branches out, it furnishes the superior vessels with an abundance of juice, by means of which all the organs are developed. At first the plant is nearly gelatinous; but it soon acquires more firmness, and continually increases in size.

This short account of the germination of seeds may suffice to shew, to the inquisitive in the wonders of nature, what preparations and means nature uses to produce a single plant. When, therefore, we see a seed that we have placed in the earth sprout, we shall no longer consider it as beneath our notice, but shall rather be disposed to regard it as one of those wonders of nature which have excited the observation and attention of some of the greatest of men.

Go, mark the matchless workings of that Power
That shuts within the seed the future flower;
Bids these in elegance of form excel;
In colour these, and those delight the smell
Sends nature forth, the daughter of the skies,
To dance on earth, and charm all human eyes.
Cowper.

Dissemination of Plants.—When seeds are come to maturity, their dissemination is absolutely necessary, since without it no future crop would follow. The great Author of nature has wisely provided for this in various ways. The stems of many plants are long and slender, and being raised above the ground, the wind shakes them to and fro, and by this means are the ripe seeds conveyed to a distance. The seed-vessels of most plants are shut till the seeds are ripe, that so the winds may not scatter them prematurely; and when the proper season arrives, many of these open with such a degree of elasticity as to throw the seeds to a considerable distance. Other seeds have a kind of wings given them, by which they are conveyed to a distance of some miles from the parent plant. These wings consist either of a down, as in most of the composite-flowered plants, or of a membrane, as in the birch, alder, ash, elm, &c. Hence woods, which happen to be destroyed by fire, or any other accident, are soon restored again by new plants.

Some seeds are rough, or provided with a sort of hooks, by means of which they are apt to stick to animals that pass by them, and by this means are carried to the mouths of their burrows, where they meet with proper soil and manure for their growth. Berries and other pericarpies are by nature allotted for aliment to animals; but it is on condition that they shall sow the seed while they eat it: this they do by dispersing the seeds as they are eating; and also after eating, by voiding many of them unhurt, and even in a better state for vegetation than they were before. Thus many kinds of nuts are sown; and thus did the doves of the Moluccas replant with nutmegs those islands of the East, which the sordid avarice of the Dutch had destroyed: Providence thereby frustrating, by feeble but certain means, the contemptible selfishness of that commercial people.

In this manner the woods of northern countries are sown with junipers, by the thrushes and other birds which feed upon these heavy berries. The cross-bill lives upon fir-cones, and the hawfinch upon pine-cones; by means of which the fir and the pine, of various species, are continually planted in vast abundance. In our own country, the common rook has been observed, not only to feed on acorns, but to make holes in the ground with the bill, and hide many: probably they mean only to lay in a stock for future necessity by this process; but certain it is, that thousands of oaks are annually planted by this means. Swine, also, in searching for food, turn up the earth; and moles, by throwing up hillocks, prepare the ground for seeds of various kinds. Seas, lakes, and rivers, by their streams and currents, often convey seeds unhurt to distant countries.

In assimilating the animal and vegetable kingdoms, LinnÆus denominates seeds the eggs of plants. The fecundity of plants is frequently marvellous: from a single plant or stalk of Indian Turkey wheat, are produced, in one summer, 2000 seeds; of elecampane, 3000; of sun-flower, 4000; of poppy, 32,000; of a spike of cat’s-tail, 10,000 and upwards; a single fruit or seed-vessel of tobacco, contains 1000 seeds; that of white poppy, 8000. Mr. Ray relates, from experiments made by himself, that 1012 tobacco seeds are equal in weight to one grain; and that the weight of the whole quantum of seeds in a single tobacco plant, is such as must, according to the above proportion, determine their number to be 360,000. The same author estimates the annual produce of a single stalk of spleen-wort to be upwards of 1,000,000 of seeds.

Prodigious Number of Plants upon the Earth.—It is said, that there are about 44,000 different plants already discovered, to which new ones are daily added. By means of the microscope, some have been found where they were least expected. The different varieties of mosses and sponges have been classed among vegetables, and have presented to the observation of the naturalist, seeds and flowers before unknown. Freestone is sometimes covered with brown and blackish spots; the mouldy substance which composes them adheres to various other matters, and may be considered as a little garden in vegetation. When we reflect upon the quantity of moss which covers the hardest stones, the trunks of trees, and the most barren places;—when we consider the quantity of vegetables upon the surface of the earth; the different species of flowers which delight and refresh us; the trees and bushes, add to these the aquatic plants, some of which exceed a hair in fineness;—we may be able to form some idea of the multitude of plants in the vegetable kingdom. All these species grow up, and are preserved without detriment or injury, each having that place assigned it, which is most suited to its properties. Such is the wisdom displayed in their distribution over the surface of the earth, that there is no part of it wholly destitute, and no part enjoys them in too great abundance. Some plants require the open field, where, unsheltered by trees, they may receive the sun’s rays; others can only exist in water; some grow in the sand; others in marshes and fens, which are frequently covered with water, and some bud on the surface of the earth, whilst others unfold themselves in its bosom. The different strata which compose the soil of the earth, as sand, clay, chalk, &c. favour different vegetables; and hence it is, that in the vast garden of nature nothing is absolutely sterile; from the finest sand to the flinty rock, from the torrid to the frozen zone, each soil and climate supports plants peculiar to itself. Another circumstance highly worthy of attention is: the Creator has so ordered, that, among this immense variety of plants, those which are most proper for food or medicine multiply in greater abundance than those which are of less utility. Herbs are much more numerous than trees and brambles; grass is in greater abundance than oaks; and cherry-trees more plentiful than apricots: had oaks been more frequent than grass, or trees than herbs and roots, it would have been impossible for animals to subsist.

According to the calculation of Baron Von Humboldt, 6000 plants are agamous, that is, plants which have no sexual organs, such as champignons, lichens, &c. Of the remainder there are found—

In Europe 7,000
In the temperate regions of Asia 1,500
In Equinoxial Asia, and the adjacent Islands 4,500
In Africa 3,000
In the temperate regions of America, in both hemispheres 4,000
In Equinoxial America 13,000
In New Holland, and the Islands of the Pacific Ocean 5,000
Total 38,000

Sensibility of Plants.—There are certain motions observable in plants, that make it doubtful whether they are not possessed of sensibility. Some plants shrink and contract their leaves upon being touched; others open and shut their flowers at certain fixed hours in the day, so regularly as to denote with precision the time of day; some assume a peculiar form during the night, folding up their leaves; and these different changes take place whether they are in the open air, or shut up in close apartments. Those which live under water during the time of fecundation, raise their flowers above the surface.

The motions of a marshy plant discovered some time since, in the province of Carolina, are still more singular. Its round leaves are furnished above, and on the sides, with a multitude of notches that are extremely irritable. When an insect happens to creep upon the superior surface of the leaves, they fold up, and inclose the insect till it dies; the leaves then open of themselves. We may daily observe regular motions in some plants in our gardens. Tulips expand their petals when the weather is fine, and close them again at sun-set, or during rain. Vegetables with pods, such as peas and beans, open their shells when dry, and curl themselves up like shavings of wood. Wild oats, when placed upon a table, will move spontaneously, more especially if warmed in the hand. And the heliotrope, or sunflower, with various other plants, always turns towards the sun. These are incontestable facts, of the certainty of which every person may be easily convinced. From them, some conclude that we ought not to deny sensibility to be an attribute of plants; and certainly the facts which are alleged in favour of such an opinion, give it great appearance of probability. But, on the other hand, plants have no other sign of sensibility; and all that they have is entirely mechanical. We plant a shrub and destroy it, without finding any analogy between it and an animal, that we bring up and kill. We see a plant bud, blossom, and bear seed, insensibly, as the hand of a watch runs round the points of the dial. The most exact anatomy of a plant does not unfold to us any organ which has the least relation to those of animal sensibility. When we oppose these observations to those from which we might infer the sensibility of plants, we remain in uncertainty, and we cannot explain the phenomena related above. Our knowledge upon this subject is very imperfect, and is confined to simple conjecture. We neither attribute sensibility to plants, nor deny it to them, with certainty.

The Sensitive Plant.—This singular plant rises from a slender woody stalk seven or eight feet in height, armed with short recurved thorns; the leaves grow upon long footstalks, which are prickly, each sustaining two pair of wings; from the place where these are inserted, come out small branches, having three or four globular heads of pale purplish flowers coming out from the side, on short peduncles; the principal stalk has many of those heads of flowers on the upper part, for more than a foot in length; this, as also the branches, is terminated by like heads of flowers; the leaves move but slowly when touched, but the footstalks fall, when they are pressed pretty hard. It is a native of Brazil, (M. pudica, humble plant,) having the roots composed of many hairy fibres, which mat slowly together; from these come out several woody stalks, declining towards the ground, unless supported; they are armed with short recurved spines, having winged or pinnate leaves; flowers from the axils, on short peduncles, collected in small globular heads, of a yellow colour.“Naturalists (says Dr. Darwin) have not explained the immediate cause of the collapsing of the sensitive plant; the leaves meet and close in the night, during the sleep of the plant, or when exposed to much cold in the day-time, in the same manner as when they are affected by external violence, folding their upper surfaces together, and in part over each other like scales or tiles, so as to expose as little of the upper surface as may be to the air, but do not, indeed, collapse quite so far; for when touched in the night during their sleep, they fall still further, especially when touched on the footstalks between the stems and the leaflets, which seem to be their most sensitive or irritable part. Now, as their situation after being exposed to external violence resembles their sleep, but with a greater degree of collapsion, may it not be owing to a numbness or paralysis consequent to too violent irritation, like the pantings of animals from pain or fatigue? A sensitive plant being kept in a dark room till some hours after day-break, its leaves and leaf-stalks were collapsed as in its most profound sleep, and on exposing it to the light, above twenty minutes passed before the plant was thoroughly awake, and had quite expanded itself. During this night the upper surfaces of the leaves were oppressed; this would seem to shew that the office of this surface of the leaf was to expose the fluids of the plant to the light, as well as to the air.” Dr. Darwin has thus characterized these plants.—

Weak with nice sense the chaste Mimosa stands,
From each rude touch withdraws her timid hands
Oft as light clouds o’erpass the summer glade,
Alarm’d, she trembles at the moving shade;
And feels alive through all her tender form,
The whisper’d murmurs of the gathering storm;
Shuts her sweet eyelids to approaching night,
And hails with freshen’d charms the rising light.


                                                                                                                                                                                                                                                                                                           

Clyx.com


Top of Page
Top of Page