Plant material

“ The worse lies of all can be statistics.'
The composition of plant materials is very dependent on the level and nature of the soil fertility that produced them. The nutrition present in two plants of the same species, even in two samples of the exact same variety of vegetable raised from the same packet of seed can vary enormously depending on where the plants were grown. ”

“ We have considered the various chemical changes which take place within the growing plant, during the formation of its woody stem, the blossoming of its flower, and the ripening of its seed or fruit,—and have traced the further changes it undergoes, when, the functions of its short life being discharged, it hastens to serve other purposes, by mingling with the soil, and supplying food to new races. ”

“ The mineral and nitrogenous constituents of plants are taken up by their roots from the soil, which is almost, if not quite, the exclusive source of these elements of plant-growth, while all of the carbon is elaborated by the leaves from the supplies in the atmosphere. ”

“ They serve as a basis in which plants may fix their roots and sustain themselves in their erect position,—they supply inorganic food to vegetables at every period of their growth,—and they are the medium in which many chemical changes take place, that are essential to a right preparation of the various kinds of food which the soil is destined to yield to the growing plant. ”

“ Plants consist of two classes of constituents—the Inorganic, which may be called the foundation; and the Organic, which may be considered the superstructure. With the former of these we are principally concerned here. A plant must derive from the soil certain proportions of silica, lime, sulphur, phosphates, alkalies, and other mineral constituents, or it cannot exist at all ”

“ From the compound substances, described in the preceding chapter, plants derive the greater portion of the carbon, hydrogen, oxygen, and nitrogen, of which their organic part consists. The living plant possesses the power of absorbing these compound bodies, of decomposing them in the interior of its several vessels, and of recompounding their elements in a different way, so as to produce new substances,—the ordinary products of vegetable life. Let us briefly consider the general structure of plants, and their mode of growth. ”

“ Instead of taking in their sustenance by means of a mouth, they suck it up by means of roots. These draw from the soil the particular nutriment that is required in the form of sap, and this is distributed to the branches and leaves of the plant. Heat and moisture are necessary in order to set the sap in motion. Air and light are imbibed by the leaves of the plants. The various colors of plants are drawn from the rays of the sun.
All plants are propagated by seeds. These, however minute, contain all the members of the parent plant—stalk, leaf and flower. ”

“ There is a period when the apple-tree blossoms with its fellows of the wood and field. How fair a time it is! All nature is woosome and winning; the material world celebrates its vegetable loves; and the flower-bells, touched by the winds of Spring, usher in the universal marriage of Nature. Beast, bird, insect, reptile, fish, plant, lichen, with their prophetic colours spread, all float forward on the tide of new life. ”

“ Receiving the water from the soil with such materials as it brings thence in solution, and absorbing carbonic dioxide and ammonia from the air, the living protoplasm of the leaf-cells has the power of chemically changing all these substances, and of producing from them those complicated and otherwise inimitable organic compounds of which the tissues of the plant are built up. ”

“ It is apparent from the above brief discussions that the rôle of the different soil elements as plant food, and their relations to the complex processes which constitute plant growth, afford an interesting and promising field for further study. ”

“ These abound in the cells of all common leaves and the green rind of plants, wherever exposed to the light. The green color is seen through the transparent skin of the leaf and the walls of the containing cells. Chlorophyll is essential to ordinary assimilation in plants: by its means, under the influence of sunlight, the plant converts crude sap into vegetable matter.
418. Far the largest part of all vegetable matter produced is that which goes to build up the plant's fabric or cellular structure, either directly or indirectly. ”

“ But the whole plant, often many feet in length, consists only of single gigantic cells. A tough skin incloses its juices, which flow in a continuous stream through the stem, leaves, and roots of the curious growth, here taking up through the skin and assimilating mineral substances, there producing and transforming organic matter, and at the same time advancing the growth and increase of the whole. Not less peculiar than the inner structure and appearance of the stem is the form of the leaves of water plants. Their service to the organism is the same with that of the leaves of other plants. ”

“ The relatively rigid nature of the plant cell-wall, and the attenuated inorganic food-supply of plants, make possible and necessary a form of growth in which the greatest surface is exposed to the exterior, and thus the plant body is composed of flattened laminae and elongated branching growths. ”

“ Though plants may be made to grow in pounded glass, or in metallic oxides, yet is the growth, in these, neither healthy nor vigorous; and,
3. All plants, on analysis, yield an earthy product; [12] and this product is found to partake most of the earth that predominates in the soil producing the analyzed plant; if silica be the dominant earth, then is the product obtained from the plant silicious; if lime prevail, then is the product calcareous, &c. ”

“ A knowledge of the composition of the ash of plants is of considerable importance in a practical point of view, and enables us in many instances to explain why some plants will not grow upon particular soils on which others flourish. Thus, for instance, a plant which contains a large quantity of lime, such as the bean or turnip, will not grow in a soil in which that element is deficient, although wheat or barley, which require but little lime, may yield excellent crops. ”

“ When we reflect that the constant removal of water in the leaf, both as such, and as the only carrier of food supplies from the roots, depends in such large measure upon the functioning of these guard cells, then we come to some realization of their importance to the plant. ”

“ The very simplest plants (if such may specifically be called plants rather than animals, or one may say, the simplest living things) are mere particles, or pellets, or threads, or even indefinite masses of protoplasm of vague form, which possess powers of motion or of changing their shape, of imbibing water, air, and even other matters, and of assimilating these into plant-stuff for their own growth and multiplication. Their growth is increase in substance by incorporation of that which they take in and assimilate. ”

“ The commonest kind of leaf, which therefore may be taken as the type or pattern, is an expanded green body, by means of which the plant exposes to the air and light the matters which it imbibes, exhales certain portions, and assimilates the residue into vegetable matter for its nourishment and growth.
119. But the fact is already familiar (10-30) that leaves occur under other forms and serve for other uses,—for the storage of food already assimilated, as in thickened seed-leaves and bulb-scales; for covering, as in bud-scales ”

“ Thus far we have spoken of plants that have roots and foliage and that depend on themselves. They collect the raw materials and make them over into assimilable food. They are independent. Plants without green foliage cannot make food; they must have it made for them or they die. They are dependent. A sprout from a potato tuber in a dark cellar cannot collect and elaborate carbon dioxide. It lives on the food stored in the tuber.
Fig. 131.—A Mushroom, example of a saprophytic plant. ”

“ And on the plant as it grows, and as a perfect whole, chemistry expends entire and most gifted intellectual lives. Of what the plant consists, whence it draws its subsistence, how it takes it in—in what form, in what quantity, at what period of the day—how the air feeds it, how the soil sustains it, why it grows well here and badly there—what are the nature, composition, action, and special influences of manures—where and when, and of what kind, they should be applied to the plant—how this or that effect is to be produced by them, and this or that defect remedied. ”

“ This fact will suggest the proper course with reference to the leaves, tops, vines, haulm, and other vegetable refuse of the garden.
The other fact connected with the leaf, is its function of Exhalation. The greatest proportion of crude sap which ascends the trunk, upon reaching the leaf, is given forth again to the atmosphere, by means of a particularly beautiful economy. The quantity of moisture produced by a plant is hardly dreamed of by those who have not specially informed themselves. ”

“ As the kernel swells with heat and moisture, its starches and albumens get oxidised and produce the motions and rearrangements of particles that result in the growth of a new plant. First a little head rises towards the sunlight and a little root pushes downward towards the moist soil beneath. The business of the root is to collect water for the circulating medium—the sap or blood of the plant—as well as a few mineral matters required for its stem and cells ”

“ There can be no doubt that the nature of the plant and the particular mode in which it gathers its nutriment, have a most important influence. Certain plants are almost entirely dependent on the soil for their organic constituents, while others derive a large proportion of them from the air, and a plant of the latter class will flourish in a soil in which one of the former is incapable of growing. ”

“ The most prominent of these parts are root, stem, leaf, flower, fruit, and seed. Familiar plants differ wonderfully in size and shape,—from fragile mushrooms, delicate waterweeds and pond-scums, to floating leaves, soft grasses, coarse weeds, tall bushes, slender climbers, gigantic trees, and hanging moss.
The Stem Part.—In most plants there is a main central part or shaft on which the other or secondary parts are borne. This main part is the plant axis. Above ground, in most plants, the main plant axis bears the branches, leaves, and flowers; below ground, it bears the roots. ”

“ They never grow into branches, but detach themselves when full grown, fall to the ground, and take root there to form new plants.
Fig. 110. Bulblets in the axils of leaves of a Tiger Lily.
117. Consolidated Vegetation. An ordinary herb, shrub, or tree is evidently constructed on the plan developing an extensive surface. In fleshy rootstocks, tubers, corms, and bulbs, the more enduring portion of the plant is concentrated, and reduced for the time of struggle (as against drought, heat, or cold) to a small amount of exposed surface, and this mostly sheltered in the soil. ”

“ On this power of expansion in the air, by which the juices of plants are quickened and strengthened, he builds his mechanical theory of growth, according to which the plastic parts of the plant assume a state of tension, and as the air enters into combination with other substances and so becomes fixed, warmth and movement are excited, and these make the particles of sap assume by degrees a form and shape. ”

“ As all the inorganic elements found in a tree and its fruits, must have been derived from the soil in which it grew, he suggested that the ashes of the plant would show us exactly what it needed, and then an examination of the soils would inform us whether they contained all the necessary elements, and in the right proportion. ”

“ You know that they are stowing away their food in warmer, safer places than can be supplied by the delicate leaves. And when all the food has been drawn out of the leaves, and packed away in the right spots, then the plant finishes a piece of work it began some time before. This piece of work is the building-up of a row of little cells just where the leafstalk joins the stem or branch. When this row is complete, it acts almost like a knife, loosening the stalk from the stem. ”

“ The plant, growing in the soil, and surrounded by the atmosphere, derives from these two sources its nourishment and means of growth through the various stages of its development.
Chemical analysis has shown that plants are composed of water, organic or combustible matters, and inorganic or mineral matters. Water constitutes by far the greater part of a living plant; a grass crop will contain about 75% of water, a turnip crop 89 or 90%. The organic or combustible matters are those which are lost, along with the water, when the plant is burnt ”

“ Leaves, on the other hand, contain 10, 20 and even 30 times as much mineral matter, there being doubtless a connection between this abundance of mineral matter and the active chemical changes which take place in the leaves during the growth of the plant. ”

“ Now that it is fit for plant food, the sap sets out to run through all the plant. It must go to every part to build all up.
There are not two sets of tubes, one for raw and one for cooked sap. All must run through the same cells. So you see, the sap will be mixed. The raw sap going up has some food sap in it. The food sap runs about with some raw sap mixed with it.
Yet, after all, each kind reaches the right place. All the raw sap is cooked, all the food sap builds the plant. Here it builds root, there leaf, there stem, there flower, or seed. ”

“ They may be best rendered intelligible by reference, in the first instance, to the changes occurring during germination, when the young plant is nourished by a supply of food stored up in the seed, in sufficient quantity to maintain its existence until the organs by which it is afterwards to draw its nutriment from the air and soil are sufficiently developed to serve that purpose. ”