Chapter V: Part 5

The rain falling through the air carries with it a certain amount of carbonic acid and ammonia, which the air always contains, and this is the whole source of the nitrogen which forms a very important part of the bodies of plants and animals. When the rain arrives at the surface of the earth, it sinks down into it and carries with it all soluble vegetable or animal matter which it meets with, together with any soluble earthy matter which may exist in the soil; this forms the sap of the tree. When it arrives at the surface of the leaf, the watery part of it combines with the carbonic acid of the air (through the influence of light) and appropriating its carbon, gives out the oxygen; this is the true respiration of plants, and is exactly the reverse of what takes place during the respiration of animals, in which case oxygen is absorbed and carbonic acid given off. The carbon thus retained by the plant combines with the elements of the water to form the solid green substance called chlorophyll, which is the basis of all the tissues of the plant, the ammonia is also decomposed, and its nitrogen combining with the oxygen and hydrogen of the water, and the carbon of the carbonic acid forms those compounds which constitute the most nourishing parts of vegetables, such as albumen, gluten, &c., and of which all the animal tissues are built up, for the production of these organic substances takes place in the vegetable only, animals simply appropriating them from their food. The sap which reaches the leaf is not all converted into chlorophyll, but also into those peculiar juices which are found in plants, some of which contain sugar, some gum, others (as the pine tribe) turpentine, and in the laurel tribe camphor, all of which are substances containing much carbon; moreover the solid wood and bark are deposited from these juices as they descend from the leaf after having been acted on by light (or the actinic power associated with it). Now, as the water, ammonia, and carbonic acid which descend with the rain are from the air, and as the vegetable is formed wholly by their absorption, it may be fairly said that the vegetable kingdom (and therefore the animal) feeds upon the air, and that the trees do not grow out of the earth but into it.

With respect to the position which the vegetable kingdom occupies in creation, there can be no doubt that it is subordinate to the animal kingdom, and takes a place between it and the mineral world, inasmuch as it prepares food from the one kingdom and transfers it to the higher. It has been supposed that the vegetable and animal kingdoms aid and support each other equally and mutually; this is true with respect to respiration, but not as regards nutrition, for although in the decomposition of animal matters, food is given off for the vegetable, yet they are quite independent of this source of nourishment. A forest of trees would be quite as well nourished if there were no animals, but on the other hand the animal kingdom would shortly cease to exist if there were no vegetables.

It was formerly supposed that the lowest grades of the animal kingdom were higher than the highest of the vegetable kingdom; this is not strictly true, the best way of viewing the connection between the two kingdoms is to approximate the lowest of each, when it will be found that our most acute physiologists are only just beginning to determine their distinctive characters.

Dr. Carpenter says:--"In the present state of science it would be very difficult, and is perhaps impossible, to lay down any definite line of demarcation between the two kingdoms, since there is no single character by which the animal or vegetable nature of any organism can be tested.

"Probably the one which is most generally applicable, among those lowest organisms which most closely approximate to one another, is not, as formerly supposed, the presence or absence of spontaneous motion, but the dependence of the being for nourishment upon organic compounds already formed, which it takes (in some way or other) into the interior of its body, or its possession of the power of obtaining its own alimentary matter by absorption from the inorganic elements on its exterior. The former is the characteristic of the animal kingdom as a whole, the latter is the attribute of the vegetable."

Both vegetables and animals begin with a simple nucleated cell, having certain vital properties, a double chain ascends from this simple type, one branch of which is developed more and more till it arrives at a perfect vegetable, and the other branch is developed till it arrives at a perfect animal. Thus, by the addition of distinctive and characteristic appendages, one being acquires properties regarded as vegetable, while by the addition of other appendages equally characteristic, the other being obtains those properties which cause it to rank as an animal; but it must not be inferred from this that all organic forms have been a simple cell at some former period, but that there are two classes of organic beings, the vegetable and the animal, and that each embraces forms, ranging from a simple cell to the highest, and that each of these forms (from the lowest to the highest) is and always was, from their first creation, the same as they now are, in individual shape and size. Some of the lower members of the animal kingdom resemble the higher members of the vegetable kingdom, both in outward appearance and in intimate structure; Dr. Darwin, who wrote scarce half-a-century ago, says that a tree should no more be considered as one plant than a branch of coral as one animal, for as it is found that in the coral hundreds of separate beings exist associated in one habitation, so (he says) should every bud on a tree be considered as a separate being. Even Dr. Carpenter, one of our most eminent physiologists, seems in a great measure to favour this idea. He says: "The radiata possess many points of affinity with the vegetable kingdom, and of these the circular arrangement of their parts is one of the most evident. Many species of sea-anemones, for instance, present an appearance so much resembling that of various composite flowers, as to have been commonly termed animal-flowers, a designation to which they seem further entitled from the small amount of sensibility they manifest, and the evident influence of light upon their opening and closing.

"But it is in the tendency to the production of compound fabrics, each containing a number of individuals, which have the power of existing independently, but which are to a certain degree connected with one another, that we recognise the greatest affinity in structure between this group and the vegetable kingdom. Every tree is made up of a large number of buds composed of leaves arranged round a common axis; each bud has the power of preserving its own life and reproducing the original structure when removed from the parent stem, if placed in circumstances favourable to its growth, and yet all are connected in the growing tree by a system of vessels which form a communication between them. This is precisely the nature of those structures which are formed by the animals of the class that may be regarded as the most characteristic of the group. Every mass of coral is the skeleton of a compound animal, consisting of a number of polypes, connected together by a soft flesh in which vessels are channelled out; the polypes are capable of existing separately, since each one, when removed from the rest, can in time produce a massive compound fabric like that of its parent, but they all contribute to the maintenance of the composite structure so long as they are in connection with it. In some instances the skeleton is stony, and is formed by the deposition of calcareous matter either in the centre of each fleshy column, so as to form a solid stem, or on its exterior so as to form a tube. In other cases it is horny, and then it may be a flexible axis in a delicate tube. Both the stony and horny corals often possess the form of plants or trees, and as their skeletons are often found with no obvious traces of the animals to which they belong, they have been accounted vegetable growths."

DESCRIPTION OF A VEGETABLE AND ITS PARTS.

As has been said before, it is extremely difficult to make any distinction between the lower tribes of the vegetable and animal kingdoms, and physiologists are not yet agreed, with respect to some members, as to which kingdom they belong. Their whole substance is made up of cellular tissue, and there are but few distinctions of parts, forming generally a broad foliaceous expansion called the "thallus," as in lichens and sea-weeds, or a sort of root composed of fibres and called the "mycelium," as in the fungi. But, a very few steps higher, the distinctive characters become so evident that they are impossible to be mistaken, the following description will therefore apply to vegetables of the more elevated character, such as trees or flowering plants.

Plants are fixed to the earth, and receive nourishment from it by imbibing its liquids, which circulating upwards through the porous structure of the plant itself, and becoming exposed to the air in the leaves, attract to themselves nourishment from that source also. The part of a plant which grows into the earth is called the root; this has a variety of forms, in some it is branched like the upper part, and these branches divide into rootlets or fibres penetrating deep into the ground, and absorbing nourishment in all directions, but this absorption does not take place from the whole surface of the root but from spots covering it, and from the slightly expanded ends of the fibres, these portions are formed of new and porous cellular tissue, and are called "spongioles." The part of plants which springs upwards from the earth is called the stem, if large the trunk, this divides into branches and twigs; stems in some cases continue for a distance more or less underground. The part of a potato plant, usually called the root, and from which the tubers or potatoes grow, is in reality an underground stem, and the fibres which spring from it are the roots; the underground suckers of mint are also portions of stem, and in some cases these are greatly expanded, they then obtain the names of "tubers" (as the potato), or "corm," as in the crocus and meadow saffron; when the stem is thin and runs along the ground, sending in roots at intervals (as in the strawberry), it is called a "runner," when thicker and running horizontally under the ground, it is called a "rhizome."

The stem consists of a central portion, either made up of long bundles of woody fibre running side by side, as in the endogenæ, or deposited in rings and having a central cylinder of pith, as in the exogenæ. In these the wood at the central part (or the oldest) is called "duramen," or "heart-wood," while that at the outer part or nearest to the bark (the newest), is called "alburnum" or "sap-wood." The former is the harder and the latter the softer portion. From the pith in the centre, through the woody part, rays or laminæ of cellular tissue similar to that which constitutes the pith itself, are sent outwards through the woody rings to the inner part of the bark, which they form; these are called medullary rays, and may be seen in wood which has been cut across the grain, they are often called the "silver grain," and are very evident in oak, beech, and elm, the inner part of the bark is called the "liber." The bark itself is made of cellular tissue dried and hardened by age; the outer portion (called the "epidermis") is in many cases shed, and may be constantly seen hanging loosely from the bark of the birch and other trees in loose white silvery portions. The outer part of the bark of some trees is so largely developed as to be of considerable thickness, this is especially the case in the Cork oak (_Quercus suber_), which is the cork of commerce. The bark cannot stretch as the circumference of the tree increases, it is therefore split up and cracked, which accounts for the rough state of it on those trees which do not shed the outer part.

The chief appendage of the branches, is called a leaf, it grows from a small projection called a leaf-bud, which contains the leaf rolled up. The method in which this occurs is different in different plants, in some it is folded backwards and forwards, in others doubled up with the opposite leaf alternately, and in various forms in other plants. The leaf consists of two parts, the stalk (petiole) and the blade (lamina); the blade is of different forms, and has ribs and veins covering it, in some of a reticulated or network pattern, these belong to the exogenæ, and in others running parallel, which is the kind of venation found in the leaves of the endogenæ. When leaves are placed on a stalk, they are said to be "petiolate," when without one, "sessile."

When leaves are not separated into different portions (although they may be much notched) they are said to be "simple," as in the oak or willow, but when divided into separate portions, as in the ash, they are said to be "compound."

The following are the chief forms of leaves, named according to variations of their several parts:

Lanceolate (Privet).

Ovate (Fuchsia fulgens).

Oblong (Primrose).

Cordate (White Bryony).

Palmate (Vine).]

Serrate (Rose).

Biserrate (Elm).

Crenate (Betony).

Entire (Lilac).

Digitate (Lupin).

Pinnate (Vetch).

Bipinnate (Acacia).

Pinnatifid (Crepis).

Ternate (Clover).

Biternate (Columbine).]

Obtuse (Dock).

Mucronate (Holly).

Retuce (Snowball).

Emarginate (Bladder Senna).]

At the base of many leaves are a pair of scales called stipules; the petiole or leaf-stalk is generally cylindrical, but frequently triangular, and in grasses it is flat and surrounds the stem, this is called a sheath; when leaves are narrow and not expanded into a lamina, as in the pine tribe, they are said to be "acicular."

The stalks which bear the flowers are called "pedicels," at the base of which are a pair of scales called "bracts;" when these are large and expanded, so as to enclose the flowers, they are called "spathes" (this is seen in the arum), and when there are a number of flower-stalks arising from one point the bracts there collected are called an "involucre." A flower consists of several parts, the outermost green scales, composing a set, are called the calyx, and each part of it, is called a "sepal," within this is the "corolla" or that coloured part which forms the most characteristic feature of the flower, each part of the corolla is called a "petal;" when the corolla consists of but one piece, it is called "monopetalous," and when of many, "polypetalous."

The forms of corolla vary according to the form and the mode in which the petals are placed, whether united or separated, and to what extent, whether regular or irregular; the most usual forms are the following:--

Rotate (Wheel-shaped), Woody Nightshade.

Hypocrateriform (Salver-shaped), Phlox.

Infundibuliform (Funnel-shaped), Tobacco.

Labiate (Having Lips), Bugle.

Ringent (Grinning), Sage.

Galeate (Helmet-shaped), Monk's-hood.

Pappilonaceous (Like a Butterfly), Sweet Pea.

Cruciate (Like a Cross), Cuckoo-flower.]

Within the corolla are placed the "stamens" (male reproductive organs) these consist generally of two parts, the head and stalk, the former called the "anther" and the latter the "filament," which last is sometimes absent, and the anther is said to be "sessile;" on the surface of the anther is the "pollen" or fertilising dust.

Within the centre of the flower is the "pistil" (female reproductive organ), this consists of one or several cells called "ovaries," from the pistil a tube rises, having an expanded end called the "stigma," it is by the application of the pollen dust to this stigma that the ovaries are fertilised, and the various insects, especially bees, who seek for honey, shake off by their movements the pollen from the anthers and cause it to be applied to the stigma, thus unconsciously performing a necessary office for the plant while they rob it of that only which is not required.

The stamens are sometimes separate, sometimes bound up into one or more bundles, and are placed in various situations, names are given to describe such arrangements as follows:--

Stamens in one bundle, Monadelphous.
Stamens in two bundles, Diadelphous.
Stamens in more than two bundles, Polyadelphous.
Filaments placed directly below the pistil, Hypogynous.
Placed upon the sides of the calyx, Perigynous.
On the sides of the corolla, Epipetalous.
On the top of the ovary, Epigynous.

When the ovaries are fertilised the flower dies and they begin to enlarge and ripen to form the fruit, which is the pistil enlarged, and contains the ovules ripened into seeds.

The fruits of different plants are known by various names according to the state of development of the various parts composing them. If the ripe fruit split open so as to let out the seeds (as in the common pea) it is called "dehiscent," if it do not so split (as in the apple) it is said to be "indehiscent;" the outer part of fruit is called the "pericarp," and this may be soft and fleshy as in the apple or cherry, or hard as in the filbert. The following are the names of the principal varieties of fruit:--

Gland (Acorn).

Legume (Pea).

Stobule (Hop).

Drupe (Plum).

Berry (Currant).

Capsule (Poppy).

Siliqua (Shepherd's Purse, Wallflower).

Eterio (Strawberry).

Nut (Hazel-nut).

Caryopsis (Wheat).]

The seed is the ovule ripened, it contains the germ of the future plant, called the "embryo," the outer part of the seed is called the "testa," and the space between this and the embryo is generally filled with starchy matter called the "albumen." The embryo consists of the plumule or stem, the "radicle" or root, and the cotyledons or leaves of the future plant; when the seed has but one cotyledon it is called "monocotyledonous" and when it has two "dicotyledonous."

Flowers are arranged in various ways upon the plants which produce them, and receive names accordingly; the whole arrangement of flowers is called the "inflorescence."

The following are the principal forms of inflorescence:--

The UMBEL, in which all the flower-stalks (pedicels) radiate from one point, as in the carrot (daucus carota). Umbels are sometimes compound, that is, the flowers are placed in umbels at the end of stalks themselves radiating from a point and so forming an umbel, as in the Hemlock (Conium maculatum).

The SPIKE, is that kind of infloresence in which all the flowers are seated without stalks upon a general peduncle or axis, as in the Plantain (Plantago media), in which the spike is entire, or as the Lavender (Lavandula Vera), in which the spike is interrupted, that is, the inflorescence is not continuous.

CATKIN, or AMENTUM, is the same as a spike, but in which the flowers are imperfectly developed, as in the Hazel (Corylus), Willow (Salix), White Poplar (Populus Alba), &c.

The RACEME has the inflorescence placed along a common axis or centre, the same as a spike, but with the flowers placed upon stalks instead of being sessile, as in Water-cress (Nasturtium officinale) and Red Currant (Ribes rubrum).]

The CORYMB is a form of inflorescence pretty much the same as raceme, but the flowers of which proceed upwards till they are all on a level, as in Candy-tuft (Iberis).

The PANICLE, the same as the raceme, but having the flower stalks themselves divided into branches, as in Creeping Soft Grass (Holcus mollis). This and the spike are the most usual form of inflorescence found among grasses, in many of which the panicle, however, is often contracted almost to a spike.

The CYME, this resembles the panicle shortened in such a manner as to become flattened or almost corymbose, as in the Elder Tree (Sambucus nigra), in which there are five principal stalks of inflorescence.

CAPITULUM, in which the flowers arise from a broad round head or receptacle as in the composite flowers, such as Chamomile (Anthemis nobilis); in such flowers the star-like ray of florets are called the florets of the ray, and those composing the centre the florets of the disc.

The SPADIX is that form of inflorescence in which the expanded bract, called a spathe, forms a sort of sheath inclosing the flowers. This spathe is white in the example given, and is often mistaken for part of the flower itself, as in the Wake-robin or Arum (Arum maculatum).

The vegetable kingdom is divided into three great natural families, the Acrogenæ, the Endogenæ, and the Exogenæ.

The acrogenous plants are those which as a general rule have neither branches, leaves, nor flowers; they are almost wholly made up of cellular tissue, and are many of them so minute that they are quite invisible individually to the unassisted eye, and are among the most wonderful works of the Creator, having an amount of beauty in form and elaboration of ornament bestowed on them, quite equal to anything among the higher and larger creations, and yet some of these are so small that tens of millions may be placed in the space of a cubic inch, of such are the Diatomaceæ and Desmidiaceæ.

The acrogens take an immense range in the scale of organisation, from the ferns (which appear but little inferior to the exogenæ or endogenæ, have stems and leaves, and in some cases, as in hot and moist climates, assume the size and form of a tree), to the very lowest state of vegetable existence, consisting of simple cells uniting into strings or forming simple threads, such as the green algæ which form on stagnant waters and damp ground or wood-work, and the mould or mildew which forms on all decomposing substances. The general name for these acrogens, "cryptogamia," which has been in use for a long time and is commonly still used, indicates that the reproductive organs are invisible, hence the expression used by one of Shakespeare's characters, "We have the secret of fern seed, we walk invisible;" but this is not really the case, for the "sorri" at the back of fern-leaves, are vessels filled with spore cases each having a number of angular seeds within it; the lower tribes of the acrogens do not commonly grow from seed but by an extension of their several parts by the development of the cells of which they are composed, and by their separation into portions.

Few of this tribe have anything like true woody texture, except their highest order, the ferns, which form some of the most beautiful objects in the vegetable world. Few of the family of acrogens are of much direct use to man, the mushroom tribes are very generally eaten where they abound, the lichens of the arctic regions form the food of the reindeer (the greatest friend of man in these cold climes) as well as, in part, the food of man himself; but although these lowly plants serve man but little, directly, there is not a shadow of doubt that they have as important an office to fulfil as any other family or tribe of organised creatures, whose purpose may meet the eye more plainly. For all the members of creation form, as it were, the links of one great chain, and were but one removed, though it might perchance be only some poor weed or lowly moss, yet might it cause the whole to be annihilated; for certain earthy matters enter into the structure of all plants, and it appears to be the wonderful office of some of these lowest tribes of plants to prepare this earthy matter for its reception into the systems of higher organisms, for as silica is one of the primitive rocks of the earth and is only found in fragments, from the largest to the sand on the sea-shore, which is nothing but a collection of minute fragments of quartz worn small by attrition, yet a grain of sand is a gigantic mass of rock in comparison with the thin porous hollow shells of the Diatomaceæ, &c., and by far too large to be absorbed or dissolved so as to be taken into the systems of other plants that may require it, which plants would cease to exist if this earth were not thus prepared for them; now these are the corn-bearing plants, the most useful to the animal world, and upon which it in reality depends for existence. Moreover the whole of the mould in which the higher orders of plants grow, is formed by the decomposition of the more humble grades, especially the lichens, which first take possession of the surface of bare rocks and stones, and furnish by their death food fit for the sustenance of those which follow them. Like the higher orders of vegetation, these minute plants excrete oxygen, and thus in the ocean may supply this vital element for the respiration of the various corresponding minute animal organisms which inhabit the depths of the sea and which cannot come to the surface to get it, so that the two thus supporting each other, form food for all the higher marine animals, which are finally eaten by man. So that upon some of these minute and apparently useless creatures hang the lives and well-being of many of the most important vegetables and animals.

Dr. Lindley divides the acrogens into the following orders:--

1. ALGÆ (Algals), including Sea-weeds, &c.

The Algæ include the lowest of all the vegetative organisms, the "Protophytes" (first plants). These have no individual parts, but consist of living cells, propagating by sub-division or by the union of two cells into one, causing the formation of "nuclei" or smaller cells within them, each of which becomes a parent cell after the rupture of the cell-membrane which contained them.

Dr. Carpenter, in his "History of the Microscope," says:--"The life-history of one of these uni-cellular plants in its most simple form, can scarcely be better exemplified than in the _Palmogloea macrococca_, one of those humble forms of vegetation which spreads itself as a green slime over damp stones, walls, &c. When this slime is examined with the microscope, it is found to consist of a multitude of green cells, each surrounded by a gelatinous envelope; the cell, which does not seem to have any distinct membranous wall, is filled with granular particles of a green colour, and a 'nucleus' may sometimes be distinguished through the midst of these. When treated with tincture of iodine, however, the green contents of the cell are turned to a brownish hue, and a dark-brown nucleus is distinctly shown. Other cells are seen, which are considerably elongated, some of them beginning to present a sort of hour-glass contraction across the middle; in these is commencing that curious _multiplication by duplicative subdivision_ which is the mode in which increase nearly always takes place throughout the vegetable kingdom."

The higher tribes of Algæ embrace the sea-weeds; these are for the most part broad, leaf-like expansions of "thallus," composed of cellular tissue, they sometimes grow to an enormous length. Humboldt mentions the sea-grass as extending for miles, and forming continuous extensions of two or three hundred feet, and the _Macrocystis pyrifera_ attains to the length of more than a thousand. The common Bladder-wrack (_Fucus vesiculosus_) was formerly much used to procure soda from, its ashes containing a considerable quantity, it is also used for manure; the _Laminaria digitata_ is eaten under the name of "tangle," and a nutritious jelly is made from the "Carigeen moss" (_Chondrus crispus_).

2. CHARACEÆ (Charas).

These are a kind of fresh-water Algæ, composed of tubes of cellular tissue; they are peculiar, from the fact that the spores of the plant have cilia, giving to them the powers of motion and enabling them to swim away and spread the plant afar off. It is in the Charas that the peculiar circulation of the granules of "endochrome" called "cyclosis" is best seen.

3. FUNGI (Fungals), including Mushrooms, &c.

The Fungi comprise a great variety of vegetable growths, from the mould which grows on any animal or vegetable substance, to the mushroom. Some of the moulds or mildews found on various decaying substances are peculiar to them, and in many cases exceedingly destructive. The microscopic fungus _Puccinea graminis_, is the parasite which fixes itself to corn and produces the disease known as mildew, and the _Uredo segetum_ (another microscopic fungus) causes the "smut;" the "bunt" is caused by the _Uredo foetida_, and the "spur," or "ergot," which attacks rye, is caused by the _Acinula clavis_. These fungi completely destroy the grain of corn, in which they form, and propagate in the most rapid manner; the ergot is moreover a dangerous poison to those who eat the bread made of rye infected by it. The Truffle (_Tuber cibarium_) is a kind of underground fungus, and is esteemed a dainty. Mushrooms are also fungi, and several species are sufficiently wholesome; these are the Field Mushroom (_Agaricus campestris_) and the Fairy-ring Mushroom (_Agaricus pratensis_).

4. LICHENES (Lichens),

Are those dry scaly growths forming grey, green, or yellow spots on the barks of trees and in various other places, and they grow in a sort of leaf or scale called a "thallus." They are used as articles of food and as "dye-stuffs;" the _Cetraria Icelandica_ is the "Iceland Moss" used here for making a sort of nutritious drink or jelly, the natives of Iceland, however, use it as common food; the _Cladonia rangifarina_, or Reindeer Moss, is the chief food of that useful creature which forms the whole property of the Laplander; and the _Roccella tinctoria_ is the substance from which the dye called "archil" is procured.

5. FILICES (Ferns).

The Ferns are a very numerous order of acrogenous plants, growing in the temperate regions from a rhizome or underground stalk (commonly called its root), which throws up "fronds" or leaves with a strong midrib; this midrib is commonly called its stalk, but in tropical countries the fern stalk rises above ground to the height of 30 or 40 feet, and then it is seen that the ordinary stalks are but the midribs of the fronds. There are between two and three thousand species of fern. The fronds open in a peculiar manner, unwinding as it were from a round ball. The "sorri" or seed-cases are situated at the back of the fronds in little brown spots, each of which is found to consist of a heap or collection of round capsules, and if these be placed under the microscope they have the appearance of little membraneous cases covered with net-like markings, and at the upper part a striated band of a brown colour, which after a time stretches out into a nearly straight line, tearing open the bag or capsule, and a number of seeds escape. Ferns grow best in damp and shady situations, and will thrive well in damp mould under a glass case.

6. MARCHANTIACEÆ (Liver-worts).

These Liver-worts are much like Lichens, growing between and upon stones near springs and moist places, and forming a broad thallus or root from which grow cup-shaped sporangia or seed-cases. The _Marchanta polymorpha_ is one of its chief members.

7. JUNGERMANNIACEÆ (Scale-mosses).

The Scale-mosses grow in moist places and under the stems of trees and plants. Their appearance is scaly, and they have a sort of stalk.

8. BRYACEÆ (Urn-mosses).

Urn-mosses comprise the most ordinary of the mosses, the "Brium," which grows on the ground everywhere, forming tufts; its fructification resembles an urn, and hence its name.

9. LYCOPODIACEÆ (Club-mosses).

These are very beautiful mosses, of a bright green colour, growing in moist places. There are about 200 species of club-mosses known. The common Lycopodium is its most characteristic member. It grows well with ferns under a glass case.

10. EQUISETACEÆ (Horsetails).

The Equisetaceæ are the highest of the Acrogens, and nearly resemble the Endogens; they grow in ditches and pools, have a hollow stem with joints at regular intervals from each of which a whorl of green modified leaves arises; they are very full of earthy matter (silica), and one kind (_Equisetum Hyemale_), called Dutch Rush, is so rough with it that it is used for polishing and scraping many articles.

The second division of the vegetable kingdom are the Endogenæ, which are those plants growing from a central bud only, as the palms, bamboos, and canes of all kinds, the grasses and all graminiferous or grain-bearing plants, as wheat, barley, &c. They have but one cotyledon in the seed and have no bark, but in place thereof a kind of natural varnish or thin coating of silica; this varnish or external polish is seen in the stalks of corn and on canes. Their leaves are often of great size, the veins run parallel to each other (fig. 8), they often grow from an expanded base which surrounds the stalk as in corn, and branch off at regular intervals making knobs or joints, as may be seen in the bamboo cane (figs. 9 and 10), in other cases they branch off spirally, and when fallen form a sort of trellis-work on the stem (as in some of the palms) but always in a regular manner. The wood of this family of vegetables has the same porous structure as cane (figs. 11, 12, 13,14), and is often hollow in the centre, becoming more and more solid according to the age of the tree. The stems of these plants are limited in growth and soon acquire their full size, which never exceeds eighteen or twenty inches in diameter although some of the palms are nearly 150 feet high. When the stem has acquired its full size, the continual production of more woody fibres makes it impossible that these (like the exogenæ) can have a very extended period of existence, for when every part of the stem is full of woody matter, the plant ceases to grow from obstruction to the circulation of the juices. The stems of some of this family are always hollow like the stalks of corn; this arrangement allows of great elevations without bending, and is found to be the form which gives the greatest strength from a given quantity of material--one of those beautiful mechanical perfections of nature which man first admired and then endeavoured to imitate.

Some of the palms and other endogenæ are of a most beautiful form, and are moreover quite as useful as beautiful, furnishing food to the inhabitants of many regions, especially the Arabs of the Desert, who carry the dried fruit of the Date-palm with them, on crossing these vast plains of sand, as their chief food. The Plantain (_Musa sapientum_) forms a most beautiful and graceful object, with its enormous leaves springing up from the ground by their midrib in clusters, and extending upwards for 20 or more feet in graceful curves, affording a shady and cool retreat beneath them from the burning rays of the sun; the fruit is also one of the necessaries of life in the regions where they abound. The Fan-palm is another beautiful specimen, from the fan-like leaves of which the punkahs or Indian fans are made. The Palmyra palm furnishes leaves which are used to thatch houses, the sap is drunk as a refreshing beverage, and when evaporated yields a kind of sugar called "juggery," from which palm-wine is made.

The palms were amongst the first trees created, their fossil stems being constantly found; they were even then associated with the elephant and rhinoceros, and although these are found chiefly in the northern parts of Europe, yet it is much more reasonable to suppose that the climate of these parts has changed, than that these two favourites of the sunny regions should have had their natures changed.

Among the useful members of the endogenæ may be mentioned the Maranta Arundinaceæ, or Arrow-root plant, which is thus described by Dr. Baird:--"It is a genus of monocotyledonous plants, belonging to the natural order Cannaceæ or Marantaceæ, and composed of herbs which have a well-developed rhizome or tuberous root containing a large quantity of fecula or starch. The species are natives for the most part, of tropical America, a few being also found in India. The structure of the flowers is remarkable, and the fruit fleshy. The most important species is the Maranta Arundinaceæ, a plant which is extensively cultivated in the West Indies, the southern parts of the United States, and in the Isle of France, for the sake of its root, which affords the substance so well-known as Arrow-root. This root consists of a tuber of a peculiar form, and contains a large proportion of fecula; the stem is upwards of three feet high, and the flowers are white, delicate, and small. In Cayenne the tubers are eaten by the natives, roasted, as a cure for intermittent fevers, and when bruised, are applied by them to wounds, and considered more especially as a specific against those caused by poisoned arrows, hence the name of Arrow-root."

According to Dr. Livingstone, the inhabitants of Angola live almost exclusively upon the Tapioca plant. He thus describes the mode of preparing it, &c.:--"They (speaking of the half-caste Portuguese) subsist chiefly on the Manioc, and as that can be eaten either raw, roasted, or boiled, as it comes from the ground, or fermented in water and then roasted or dried after fermentation and baked, or pounded or rasped into meal and cooked as farina, or made into confectionery with butter and sugar, it does not so soon pall upon the palate as one might imagine when told that it constitutes their principal food. The leaves, boiled, make an excellent vegetable for the table, and when eaten by goats, their milk is much increased. The wood is a good fuel, and yields a large quantity of potash.... The root, rasped while raw, placed upon a cloth, and rubbed with the hands while water is poured upon it, parts with its starchy glutinous matter, and this, when it settles at the bottom of the vessel and the water is poured off, is placed in the sun till nearly dry to form tapioca, the process of drying is completed on an iron plate over a slow fire, the mass being stirred meanwhile with a stick; when dry, it appears agglutinated into little globules, and is in the form we see in the tapioca of commerce."

Although none of this family of plants produce building timber (according to our notions of that article), yet it is questionable whether we have a greater number of uses for our exogenous woods than are found by the natives of those countries where the Endogenæ abound for palm stems and bamboo canes; as the Grecian styles of architecture arose from the imitation of structures of timber, so the Hindoo and Chinese styles have arisen from imitation of bamboo buildings. There is scarcely a constructive use that can be imagined to which this convenient material is not applied. In the "Penny Cyclopædia" (article "Bambusa") is the following:--

"The purposes to which different species of bamboo are applied, are so numerous that it would be difficult to point out an object in which strength and elasticity are requisite, and for which lightness is no objection, to which the stems are not adapted in the countries where they grow. The young shoots of some species are cut when tender, and eaten like asparagus. The full-grown stems, while green, form elegant cases, exhaling a perpetual moisture, and capable of transporting fresh flowers for hundreds of miles; when ripe and hard, they are converted into bows, arrows, and quivers, lance-shafts, the masts of vessels, bed-posts, walking-sticks, the poles of palanquins, the floors and supporters of rustic bridges, and a variety of similar purposes. In a growing state the spiny kinds are formed into stockades, which are impenetrable to any but regular infantry aided by artillery.

"By notching their sides the Malays make wonderfully light scaling-ladders, which can be conveyed with facility where heavier machines could not be transported. Bruised and crushed in water, the leaves and stems form Chinese paper, the finer qualities of which only are improved by a mixture of raw cotton, and by more careful pounding.

"The leaves of a small species are the material used by the Chinese for the lining of their tea-chests. Cut into lengths and the partitions knocked out, they form durable water-pipes, or by a little contrivance are made into excellent cases for holding rolls of papers; slit into strips they afford a most durable material for weaving into mats, baskets, window-blinds, and even the sails of boats. Finally, the larger and thicker truncheons are exquisitely carved by the Chinese into beautiful ornaments. It is however more especially for building purposes that the bamboo is important (fig. 15). According to Marsden, in Sumatra the framework of the houses of the natives is chiefly composed of this material. In the floorings, whole stems four or five inches in diameter are laid close to each other, and across these laths of split bamboo about an inch wide are fastened down with filaments of rattan-cane. The sides of the houses are closed in with the bamboo opened and rendered flat by splitting or notching the circular joints on the outside, clipping away the corresponding divisions within and laying in the sun to dry pressed down with weights. Whole bamboos often form the upright timbers, and the house is generally roofed in with a thatch of narrow split bamboos six feet long, placed in regular layers, each reaching within two feet of the extremity of that beneath it, by which a treble covering is formed. Another and most ingenious roof is also formed, by cutting large straight bamboos of sufficient length to reach from the ridge to the eaves, then splitting them exactly in two, knocking out the partitions and arranging them in close order, with the hollow or inner sides uppermost; after which a second layer with the outer or convex sides up, is placed upon the other in such a manner that each of the convex falls into the two contiguous concave pieces, covering their edges, the latter serving as gutters to carry off the rain that falls upon the upper or convex layer."

The Endogenæ are divided into twelve orders, as follows:--

1. GRAMINACÆ (Grasses).

The Graminacæ comprise the great bulk of those plants which supply man and the lower animals with food, for it contains all the grasses and corn-bearing plants, including rice, maize, wheat, oats, barley, and rye. Upon these all the Ruminants of the earth feed, and millions of human beings taste no other kind of food. There are nearly 4000 species of graminaceous plants, rice and maize being the most broadly extended, forming the chief food of the Chinese, Hindoos, and other nations; wheat is here the most valuable grain, and is now grown in all parts of Europe and America. Humboldt, in his "Views of Nature," gives an interesting account of the first wheat grown in New Spain. He says:--

"A negro slave of the great Cortes was the first who cultivated wheat in New Spain, from three seeds which he found in some rice brought from Spain for the use of the troops. In the Franciscan convent of Quito I saw, preserved as a relic, the earthen vessel which had contained the first wheat sown in Quito by the Franciscan monk Fra Jodoco Rixi de Gante, a native of Ghent in Flanders. The first crop was raised in front of the convent, on the Plazuela di San Francisco, after the wood which then extended from the foot of the volcano of Pinchincha had been cleared. The monks, whom I frequently visited at Quito, begged me to explain the inscription, which, according to their conjecture, contained some hidden allusion to wheat. On examining the vessel, I read in old German the words,

"'Let him who drinks from me ne'er forget his God.'

"This old German drinking-cup excited in me feelings of veneration. Would that everywhere on the New Continent the names of those were preserved who, instead of devastating the soil by bloody conquests, confided to it the first fruits of Ceres."

2. CYPERACEÆ (Sedges).

These plants much resemble the Grasses, they afford but little nourishment, however, to cattle, having but little starchy matter in them, and being but little succulent. The Cyperus Papyrus is the plant from which the ancient "papyrus" was made, and is probably (according to Dr. Baird) the plant termed in Scripture the Bull-rush.

3. ARACEÆ (Arum tribe).

The Araceæ include the Arum maculatum, or Cuckoo-pint, peculiar in having the flowers enclosed by a kind of sheath formed like a leaf, and called a "spathe." The "Portland Sago" is obtained from the Rhizome of this plant, but some of the species of this order are poisonous. The Dumb-cane (Caladium Segninum) paralyses the tongue, if chewed.

4. TYPHACEÆ (Bull-rush kind).

The Typhaceæ are the Bull-rush tribe, having the Typha latifolia or great Reed-mace for its characteristic member. It grows in ditches and marshy places. The young shoots of the Bull-rush, which resemble asparagus, are eaten by the Cossacks as food.

5. MELANTHACEÆ (Colchicum kind).

This includes many plants which have bulbous roots, some of them being poisonous. The Colchicum autumnale, or Meadow Saffron, is the type of this order; it grows in moist meadows, producing a purple flower which appears before the leaves. The root or bulb, and the seeds, are used in medicine.

6. LILIACEÆ (Lily kind).

The Liliaceæ are a very numerous tribe, including the Lilies, Hyacinths, and Tulips, the Onion, Garlic, Asparagus, the Cape Aloe, Yucca, and many others; they are for the most part bulbous plants, having simple leaves enclosing the stem. The Palms are included in this order; they are among the tallest and most graceful of the vegetable tribes, and in the countries where they abound are applied to almost every purpose that can be enumerated.

7. AMARYLLIDACEÆ (Narcissus kind).

The Amaryllidaceæ are the Narcissus tribe, including also the Agave, or American Aloe, and the Snow-drop. The greater number of species belonging to this order are natives of the Cape of Good Hope, some of these are poisonous; the juice of the Cape Blood-flower (Hæmanthus Toxicarius) is used by the Hottentots to poison their arrows with.

8. IRIDACEÆ (Crocus tribe).

The Iridaceæ include the Crocus (Crocus sativa), the Corn-flag (Gladeolus communis), and the Blue-flag (Iris Germanica); the bulb of the Iris Florentina, is dried and used for various purposes, it has a scent resembling violets and is sold at druggists' shops by the name of orris-root, a corruption of iris-root.

9. ORCHIDACEÆ (Orchids).

The family of the Orchis. Dr. Baird, in describing them, says:--"They are almost all herbaceous, a very few only being somewhat shrubby in their growth; some live in the ground, and besides the ordinary roots have bulbs or starch-bearing tubercles; others are what may be called pseudo-parasites, living attached to the bark of trees. These plants abound in the forests of tropical countries, where the climate is moist, and are generally known by the name of Epiphytes. The flowers vary very much in shape, form, and colour, and in many instances have a striking resemblance to insects, various birds, and animals, as Oncidium, in which the resemblance is to butterflies, &c.; Cychnoches, in which (in one species) the likeness is strikingly similar to a swan; Peristeria, one species of which is called the Sprito-Santo plant, of Panama, and in whose flower there is the likeness of a dove descending upon the lip, &c. A curious fact in this part of their history is, that in the same plant, on the same stem, and even on the same head of flowers, we find flowers so different in appearance that we might place them in different genera."

10. NAIADACEÆ (Naiads).

Water-plants, called "pond-weeds," and grow on both fresh and salt water. The marine species, Zostera marina, is dried and used for stuffing mattresses.

11. BUTOMACEÆ (Flowering Rushes).

Of this order the Butomas umbellatus, a sort of rush, producing very handsome pink flowers in umbels, growing in ditches and by the sides of rivers, is the most characteristic member.

12. ALISMACEÆ (Water Plantain).

The two chief members of this order are the Alisma Plantago or Water Plantain, which grows in ditches, having its flowers in the form of panicles, and the Sagittaria sagittæfolia or Arrowhead.

* * * * *

The third great natural family of plants are the Exogenæ. They comprise all the trees and shrubs of the temperate and colder regions, together with many of the flowering plants. They are characterised by certain peculiarities which can be at once recognised, such as the twisted and branched form of the stem, the possession of bark, leaves having the veins covering them running in all directions and forming a network, and the seeds containing two cotyledons; the wood, moreover, is deposited in rings (figs. 16, 17, 18, 19), one of which is formed every year, by the new wood being produced on the outside of the old, and between it and the bark. This deposition takes place as follows: after the rains of winter and early spring have well saturated the earth with moisture, and the warmth of spring has begun to penetrate to the roots of the plants, a development of the points of each fibrile or radicle takes place, forming new spongioles; these, being formed of new porous cellular tissue, begin to absorb (by endosmose) the moisture of the earth, which entering at all these thousands of minute spongioles at once, collects and rises in the vessels of the trunk and branches, and arriving at the vessels forming a plexis on the surface of every leaf, begins to be changed by the action of the sun's rays, absorbing carbon and giving out oxygen from the carbonic acid always contained in the air. The sap which has thus risen is the juice of the earth in which the plant grows, containing several earthy salts and vegetable extract drawn from the manure or decaying vegetation contained in the mould, together with carbonic acid dissolved in the fluid; this carbonic acid is changed by the sun's rays as well as that which was contained in the air, and the carbon uniting with the watery part of the sap, forms the green substance before alluded to, called chlorophyll, which is the green colouring matter of all plants, and is the basis of the wood. The altered sap descends between the wood and the bark, and forms a deposit gradually, which at the end of the year is a complete ring of wood surrounding the wood of former years. This circulation of juices continues through the summer, until, the cold weather coming on and the light being diminished, the sap neither rises nor is the leaf nourished by it, when it decays and falls off.

The age of exogenous wood can be ascertained--where the centre has not decayed--by counting the rings, one only being deposited every year; and it is truly astonishing to find that some trees will continue to live and flourish for several thousand years! There does not, in truth, appear to be any limit assigned to the life of an exogenous tree if it escape accidents; for, although decay inevitably attacks the heartwood, and a cavity is the result, yet, the new wood continuing to be deposited on the outer part, the vitality of the tree is kept up, and its size continues to increase.

The Baobab or Monkey Bread-fruit trees, growing at the mouths of the Senegal, have been estimated by Adinson to be upwards of six thousand years old, and are, in all probability, the oldest relics of organic life existing at the present time. The cedars of Lebanon are supposed to have existed longer than the records of history. The Yew at Braburn, in Kent, is at least three thousand years old; and that of Fortingal nearly as much.

Dr. Livingstone, describing the Mowana or Baobab tree (fig. 20), thus comments upon its power of withstanding injury:--