ROOT, in botany, sometimes designated the descending axis of a plant, that part by which it is fixed to the soil and derives nourishment from the soil. The root is devel oped in the germination of the seed, at or about the same time with the stem, and forces its way downward as the stem grows upward. The root differs from the stem in the irregularity of its ramifications, in the want of a central pith, in the want of ,buds, in the want of scales or of scars to indicate their former presence, and in the want of stomata. The axis of the root giving off branches, these finally subdivide into fibrils, which are little bundles of annular ducts, or sometimes of spiral vessels incased in woody fiber, a:1d covered with a lax cellular integument. The apex of each fibril is sometimes called the spongiole: it consists of extremely lax cellular tissue, and has the property of absorbing fluids with great rapidity, thus subserving the nourishment of the plant. See ENDOS mom—Aerial roots occur in sonic plants, as in sonic epiphytes, the mangroves, etc.; by which nonrishment is derived from the air, in addition to that obtained through' the leaves and bark, or by which the branches seek to coundct themselves anew with the ground for support and nourishment; and many plants, as willows, produce adven titious roots very readily, when any portion of the stem or branch is imbedded in moist soil, of whitth advantage is taken for their artificial propagation.—The central axis of many roots goes deep into the ground in a tapering manner, forming what is called a takrool; other roots have the descending axis very short, and arc called ,fibrous. The
roots of some plants spread very widely; those of others occupy a very limited space. Roots of coniferous trees and palms are very small when compared with the appearance of the tree above ground.—Tap roots sometimes assume a conical form, as in the car rot;• others are variously developed in thickness at the part, as in the turnip and radish. Tubers (q.v.), bulbs (q.v.), and corms (q.v.)are peculiar developments, evidently intended to secure a store of nourishment for the plant, but which also are very fre quently avabAble for the use of man.—Esculent roots are numerous, and many roots also contain secretions either peculiar to themselves, or more abundant than in the other parts of the plant, and become therefore useful in medicine or in the arts, while some are very poisonous. The roots used for food, besides the tubers, bulbs, and corms above mentioned, are generally those which are thick and fleshy. The plants to which they helon,7 ate of vet y different genera and orders—some of the natural order crucifers, as the turnip and oth•ms of the genus brassica—some of the order cltenopodiacca, as beet and mangold wtrzei—some of the order umbellifcree, as the carrot,. parsnip, cte.—some of the order as the pachyrhizos angulatus, which is cultivated in all parts of the East Indies, trilobus, which is cultivated in Cochin China. In many of the lower classes of plants, particularly the algae, there is no root whatever, although the plant is often attached by a base.