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Of the Root.
The root (radix) is that part of the vegetable which enters the earth, and extends in a direction contrary to the growth of the stem; it supports the plant in an upright position, and at the same time gives nourishment to every part of it. There are exceptions to the general fact, of a root being fixed in the ground; some plants, as the pond-lily, grow in water, and are called aquatic, (from aqua, water,) some, like the misletoe, have no root, but fix themselves upon other plants, and derive sustenance from them; such are called parasites.*
The Root consists of two parts, the Caudex, or main body of the root, and the Radicle, or fibres; these are a kind of capillary or hair-like tubes, which absorb the nourishment that is conveyed to other parts of the plant. This nourishment ascending by the action of the air, experiences in the leaves and green parts of the plant, an important change; and a part of it, through a different set of vessels, flows back, in what is called the returning sap or cambium.
Between the Caudex and stem is a point, sometimes called the rootstock which is considered as of peculiar importance; any injury to this part being followed by the death of the plant.
Duration of Roots.
Roots with respect to duration are, annual, biennial or perennial.
Annual roots-are such as live but one year. They come from the seed in the spring, and die in autumn, including such as are raised from the seed every year: as peas, beans, cucumbers, &c.
Biennial roots-are such as live two years. They do not produce any flowers the first season, the next summer they blos som, the seeds mature, and the roots die. The roots of cabbages are often, after the first season, preserved in cellars during the winter. In the spring they are set out in gardens, and produce flowers; the petals of which, in time, fall off, and the germ grows into a pod or silique, which contains the seed. The root having performed this office, then dies, and no process can restore it to life; the flowering is thought to exhaust the vital energy or living principle. The onion, beet and carrot are biennial plants.
*The word parasite, from the Greek para, with, and sitos, corn, was first applied to those who had the care of the corn used in religious ceremonies, and were allowed a share of the sacrifice; afterwards it was applied to those who depended on the great, and earned their welcome by flattery; by analogy, the term is now applied to plants which live upon others.
Definition of the root-Aquatic roots-Parasites-Division of the root-Annual roots-Biennial.
Perennial roots- -are those whose existence is prolonged a number of years to an indefinite period; as the asparagus, ge. ranium, and rose; also trees and shrubs. Climate and cultivation affect the duration of the roots of vegetables. Many perennial plants become annual by transplanting them into cold climates: the garden nasturtion, originally a perennial shrub in South America,has become in our latitude an annual plant. Botanists express the duration of vegetables by the use of astronomical signs; the annual plants are designated thus, denoting one revolution of the earth around the sun.
The biennials are represented by ♂, the planet mars, which makes its revolution in two years.
The perennials are represented by 2, the planet Jupiter, which makes its revolution in many years.
The character h, the sign of the planet Saturn, is used to designate woody plants which usually live many years.
It is said, that great care in the culture may prolong the life of annual plants beyond what appears to be their natural term of existence.
Forms of Roots.
There are seven varieties in the forms of roots; branching, fibrous, spindle, creeping, granulated, bulbous.
1st. Branching ramosa.) (Fig. 12.) This is the most common
it consists of numerous ramifications, resembling in appearance the branches of a tree; some of these branches penetrate to a great depth in the earth, and others creep almost horizontally near its surface.
Experiments have been made, which show, that branches by being buried in the soil may become roots; and roots, by being elevated in the atmosphere, become branches covered with foliage. We often see the roots of trees, which have been blown down, throwing out leaves.
Branching roots terminate in fibres or radicles, which are in reality the proper roots; as they imbibe through pores, the nourishment which the plant derives from the earth. Nature
Perennial roots-Classification of roots as founded upon their forms-Branching root.
furnishes this nourishment in the moisture, and various salts which are contained in the soil.
2d. Fibrous Root, (Radix fibrosa.) (Fig. 13.) This consists of a collection of threadlike parts; as in many kinds of grasses, and most annual plants. The fibres usually grow directly from the bottom of the stem, as may easily be seen by pulling up a handful of the most common grass.
3d. Spindle root (Radix fusiformis.) (Fig. 14.) This is large at the top, and tapering downwards; as beets; carrots, radishes, and many of the bien. nial plants. This root is not well provided with the means of imbibing sustenance, on account of a deficiency of radicles; it is sometimes furnished with no more than one. That these radicles are the agents, by which the root is nourished, may be seen by immersing a young radish in water until every part is covered except the radicles; the herbage will soon die; but if the radicles of another radish are immersed in water, the plant will live and look fresh for some time. The spindle root is often forked as in the mandrake,* the divisions of which are thought to resemble the lower part of the human figure. Sometimes the spindle root instead of termimating in a point, appears as if the end had been cut or bitten off; this is called an abrupt root, or more scientifically, premorse, (See Fig. 15.) which signifies bitten. The violet and cowslip furnish examples of this kind of root. A foreign plant called the Devil's bit,t received the name on account of its abrupt root; it having been superstitiously believed in former times, that as the plant was useful for medicine, the devil had, out of spite to mankind, bitten off
Atropa Mandragora. The word mandrake is said to be derived from the German Mandragen, resembling man.
† SCABIOSA succisa or a kind of Scabious.
Fibrous root-Spindle root-Importance of radicles-Forked spindle rootPremorse root.
root (Radix repens.) (Fig. 16.) This root, instead of forcing its way perpendicularly in to the earth, extends horizontally, and sends out fi
bres. It is very tenacious of life, as any part of it containing a joint will grow. This root is sometimes useful, by its fibres spreading and interlacing themselves, and thus rendering a soil more permanent. Holland would be liable to be washed away by the action of water were it not that its coasts are bound together by these and other plants. This root will grow in sandy, light soils, which scarcely produce any other vegetation. Fig. 17.
5th. Granulated root (Radixgranulata.)(F. 17.) This consists of
or tubers, strung together by a thread-like radicle; this form approaches to that of some varieties of the tuberous.
6th. Tuberous root (Radix tuberosa.) Fig. 18.) This kind of root is hard, solid, and fleshy; it consists of one knob or tuber; as in the potatoe, a; or of many such connected by means of a number of strings or filaments, as in the artichoke, b. These tubers are reservoirs of moisture, nourish. ment and vital energy. The potatoe is in reality, but an excrescence, proceeding from the
real root; and it is a singular fact that this nutricious substance is the product of a plant whose fruit (often termed potatoe balls) is poisonous. The root of some of the orchis plants consists of two tubers, resembling the two lobes into which a bean may be divided, c. Tuberous roots are knobbed as in the potatoe; oval, as in the orchis; abrupt, as in the plantain; fasciculated, when several are bundled together, as in the asparagus, and several species of orchis.
7th. Bulbous root (Radix bulbosa.) (Fig. 19.) A fleshy root of a bulbous or globular form. It seems like a large ball placed under ground, to enclose and protect the future plant. Bulbous plants belong chiefly to the great division of Monocoty ledons, or those whose seeds have but one cotyledon; they produce some of the earliest flowers of spring, and afford some of the most beautiful ornaments of the garden. Among them are the Hyacinth, the Crown Imperial, the Lily, and the Tulip, with a great variety of other splendid and interesting flowers. The use of the bulb being to preserve the future plant from the effect of cold, we see the bountiful agency of Providence in the greater number of bulbous plants in cold countries.
Bulbs seem to be analogous to the buds of trees, and in some plants they grow like buds upon the stems or branches; as in one species of lily and the magical onion; in the latter of which the bulbs or onions grow upon the stalk in clusters of four or five; they continue to enlarge, until their weight brings them to the ground; here, if not prevented, they take root. This is a viviparous plant, or one which produces its offspring alive; such plants as produce seeds, or such animals as produce their offspring from eggs, are called oviparous. Bulbs are solid, as in the turnip (Fig. 19, a), scaly, as in the lily (b), and tunicated or coated (c), as in the onion.
Tubers, as the potatoe, not the real root-Different forms of tuberous rootsBulbous root-Use of the bulb--Analogous to buds-Viviparous and oviparous plants-Different forms of bulbous roots-Difference in the production of plants by means of bulbs and seeds.