Root (botany)

“ In its growth a root turns or bends away from the light and toward the centre of the earth, so that in lengthening it buries itself in the soil where it is to live and act. Every one must have observed this in the germination of seeds. Careful observations have shown that the tip of a growing root also makes little sweeps or short movements from side to side. ”

“ Any part of the stem may produce them, but they most readily come from the nodes. As a general rule they naturally spring, or may be made to spring, from almost any young stem, when placed in favorable circumstances,—that is, when placed in the soil, or otherwise supplied with moisture and screened from the light. For the special tendency of the root is to avoid the light, seek moisture, and therefore to bury itself in the soil. Propagation by division, which is so common and so very important in cultivation, depends upon the proclivity of stems to strike root. ”

“ In the last edition of the 'Pemptades ' of Dodoens [9] of the year 1616, a folio volume of 872 pages, only one page and a third are devoted to the explanation of the parts of plants; but the selection of the words explained and the substance of the explanations hit the essential points better than in Fuchs. We find for instance: Root ('radix, ῥιςα') is the name given in the tree and in every other plant to the lower part, by which it penetrates into the earth and cleaves to it, and by which it draws its nourishment. ”

“ Of this kind are the so-called creeping, running, or scaly roots, such as those by which the Mint (Fig. 97) , the Couch-grass, or Quick-grass, and many other plants, spread so rapidly and widely,—"by the root," as it is said. That these are really stems, and not roots, is evident from the way in which [Pg 43] they grow; from their consisting of a succession of joints; and from the leaves which they bear on each node, in the form of small scales, just like the lowest ones on the upright stem next the ground. They also produce buds in the axils of these scales, showing the scales to be leaves ”

“ If the function of the root is to draw food from the earth, and of the stem to bear the seeds, and the two cannot exchange functions, so that the root should bear seeds and the shoot penetrate into the earth, there must either be two souls different in kind and separate in place, the one residing in the root, the other in the shoot, or there must be only one, which supplies both with their peculiar capabilities. ”

“ The entire mass of roots of any plant is called its root system. The root system may be annual, biennial or perennial, herbaceous or woody, deep or shallow, large or small.
Kinds of Roots.—A strong leading central root, which runs directly downwards, is a tap-root. The tap-root forms [33] an axis from which the side roots may branch. The side or spreading roots are usually smaller. Plants that have such a root system are said to be tap-rooted. Examples are red clover, alfalfa, beet, turnip, radish, burdock, dandelion, hickory (Figs. 32, 33) . ”

“ The protoplasmic lining of the cell wall is such a membrane. The soil water being a weaker solution than the sap in the roots, the flow is into the root. A strong fertilizer sometimes causes a plant to wither, or “burns it.” Explain.
Structure of Roots.—The root that grows from the lower end of the caulicle is the first or primary root. Secondary roots branch from the primary root. Branches of secondary roots are sometimes called tertiary roots. Do the secondary roots grow from the cortex, or from the central cylinder of the primary root? ”

“ 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. ”

“ The roots grow here and there in search of food, often extending much farther in all directions than the spread of the top of the plant. Roots tend to spread farther in poor soil than in rich soil, for the same size of plant. The root has no such definite form as the stem has. Roots are usually very crooked, because they are constantly turned aside by obstacles. Examine roots in stony soil. ”

“ Fig. 46.—Root-hair, much enlarged, in contact with the soil particles (s) . Air-spaces at a; water-films on the particles, as at w.
The root-hairs are very small, often invisible. They, with the young roots, are usually broken off when the plant is pulled up. They are best seen when seeds are germinated between layers of dark blotting paper or flannel. On the young roots they will be seen as a mould-like or gossamer-like covering. Root-hairs soon die: they do not grow into roots. New ones form as the root grows. ”

“ And when growth ceases above ground, and the leaves die and fall, or no longer act, then the roots generally stop growing, [Pg 35] and their soft and tender tips harden. From this period, therefore, until growth begins anew the next spring, is the best time for transplanting; especially for trees and shrubs.
73. The absorbing surface of young roots is much increased by the formation, near their tips, of Root-hairs (Fig. 81, 82) , which are delicate tubular outgrowths from the surface, through the delicate walls of which moisture is promptly imbibed. ”

“ Fig. 48.—The Marking of the Stem and Root.
The Root-cap.—Note the form of the root-cap shown in the microscopic section drawn in Fig. 47. Growing cells, and especially those which are forming tissue by subdividing, are very delicate and are easily injured. The [45] cells forming the root-cap are older and tougher and are suited for pushing aside the soil that the root may penetrate it.
Region of most Rapid Growth.—The roots of a seedling bean may be marked at equal distances by waterproof ink or by bits of black thread tied moderately tight. ”

“ They are light green on one side, and whitish or gray on the other. Each leaf has its own brown, hairy and hollow stem, on which it sits like a wide hat or a mushroom turned over. The root grows very thick, is white and porous inside, and has a strong, bitter taste. ”

“ Stem strictly erect from an annual root, and with the upright or ascending branches wing-angled or grooved; leaves alternate, linear, acute, the upper subulate and glandular-serrulate; a pair of dark glands in place of stipules; sepals ovate-lanceolate and sharp-pointed, strongly 3-nerved and with rough-bristly-glandular margins, scarcely longer than the ovoid-globose incompletely 10-celled pod; styles united almost to the middle.—Dry soils, E. Mass. to Minn., and southwestward.—Flowers and pods twice as large as in the preceding. ”

“ 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. ”

“ Those living surfaces of the plant which are most exposed to light are green or highly coloured. The root tends to grow downward, but the stem tends to grow upward toward light [16] and air. The plant is anchored or fixed in the soil by the roots. Plants have been called “earth parasites.”
The Foliage Part.—The leaves precede the flowers in point of time or life of the plant. The flowers always precede the fruits and seeds. Many plants die when the seeds have matured. The whole mass of leaves of any plant or any branch is known as its foliage. ”

“ It seems best, therefore, to take it up before examining the buds.
1. Study of the Roots of Seedlings.—One or two of the seedlings should be broken off and the slips put into a glass of water. They will be studied later. Bean and Sunflower are the best for the purpose.
Begin by telling the pupils to prepare for their first lesson a description of the roots of their seedlings. Those grown on sponge or paper will show the development of the root-hairs, while those grown on sand are better for studying the form of the root. Give them also some fleshy root to describe, as a carrot, or a radish ”

“ A store of food for the second year. that creep through the earth seeking food for the tree. Some, as in the spruce or hemlock, do not go very deep but spread great distances through the soil in search of food, others, like the hickory, go nearly straight down. The interesting feature of these tree roots is that the part nearest the trunk is all but dead, and acts mostly as an anchor, while the fibrous rootlets or even finer subdivisions known as root hairs at the extremities are the food gatherers. ”

“ The final causes of many of these facts are easy to comprehend: the reason why a root grows down into the earth, is for the purpose of obtaining that sustenance which is necessary for the growth of the plant of which it is a part; and stems grow upwards, and towards the light, because the influence of this element is necessary for the elaboration of the sap; as a result of which process, stems grow in thickness, roots in length, flowers are developed, and the proper juices of vegetables become formed. ”

“ The root holds the plant firmly in the ground and takes in water and mineral matter from the soil; the stem holds the leaves up to the light and acts as a pathway for fluids between the root and leaves; the leaves, under certain conditions, manufacture food for the plant and breathe; the flowers form the fruits; the fruits hold the seeds, which in turn hold young plants which are capable of reproducing adult plants of the same kind. ”

“ When a seed sprouts, the root, I have told you, goes down into the ground, while the stalk goes upward into the air. The root goes down because the food of the plant is in the ground. It is the business of the root to suck up this food, so that the plant may be nourished and grow. The root is, then, a sort of stomach to the plant. If it had no root it would not grow, any more than you would if you had no stomach to put your food in. ”

“ STEMS AND SEED LEAVES The smaller plants usually have green stems. The larger ones have brown, woody stems, such as you see in bushes and trees; for the trunk of the biggest tree in the world is nothing but a great stem.
The delicate green stems die down to the ground during the cold winter. Sometimes the whole plant [Pg 120] dies, the root below as well as the stem above ground. But often the root (or what we usually call the root) lives, and sends up a fresh stem the next year. ”

“ Roots are most easily extricated from light soil, and with least fracture. They are large in proportion to stem in dry soil and climate, and when they are situated near the surface of the ground.—A healthy growing plant, of firm fibre, large root, and sturdy short stem of one leader and numerous feeders, is the great desideratum: a large root is the more desirable, as a considerable part of it is generally broken off in transplanting, rendering it disproportioned to the top, which, in consequence, either languishes, or receives deterring cropping. ”

“ These hairs are the feeding-organs of the roots, and they are formed only near the tips of the finest roots. You see that the large, coarse roots that you are familiar with have nothing to do with absorbing plant food from the soil. They serve merely to conduct the sap and nourishment from the root-hairs to the tree. ”

“ Once it finds itself firmly rooted in the stem of its victim, it begins to grow vigorously. With every few inches of its growth it sends new roots deep into this stem. And when it feels quite at home, and perfectly sure of its board, it begins to wither away below, where it is joined to its earth root. Soon it breaks off entirely from this, and draws every bit of its nourishment from the plant or plants in which it is rooted. ”

“ If you repeat this often with many plants you will find that these are the actively growing parts of the stems and roots; the individual leaves, of course, are also growing. Thus we see that growth is not a simple stretching of the whole, but that there are two definite regions where it is specially active. That of the stem and first root carry on the growth in opposite directions, as we noticed before (see p. 11) , the normal stem growing up into the air and the root down into the soil. ”

“ Many plants are grown from roots or bulbs, but a greater majority by far come from seed. Tulips and lilies, onions and potatoes, are all instances of plants grown from roots which sprout out from the old ones. The root is in every case the beginning, the seed the ending, of the life of a plant. ”

“ Ordinary Herb True-love has a small creeping root running under the uppermost crust of the ground, somewhat like couch grass root, but not so white, shooting forth stalks with leaves, some whereof carry no berries, the others do ”

“ 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 ”