When a root is of a birth yknowe [known]. Chaucer.

Aërial roots. (Bot.) (a) Small roots emitted from the stem of a plant in the open air, which, attaching themselves to the bark of trees, etc., serve to support the plant. (b) Large roots growing from the stem, etc., which descend and establish themselves in the soil. See Illust. of Mangrove. -- Multiple primary root (Bot.), a name given to the numerous roots emitted from the radicle in many plants, as the squash. -- Primary root (Bot.), the central, first-formed, main root, from which the rootlets are given off. -- Root and branch, every part; wholly; completely; as, to destroy an error root and branch. -- Root-and-branch men, radical reformers; -- a designation applied to the English Independents (1641). See Citation under Radical, n., 2. -- Root barnacle (Zoöl.), one of the Rhizocephala. -- Root hair (Bot.), one of the slender, hairlike fibers found on the surface of fresh roots. They are prolongations of the superficial cells of the root into minute tubes. Gray. -- Root leaf (Bot.), a radical leaf. See Radical, a., 3 (b). -- Root louse (Zoöl.), any plant louse, or aphid, which lives on the roots of plants, as the Phylloxera of the grapevine. See Phylloxera. -- Root of an equation (Alg.), that value which, substituted for the unknown quantity in an equation, satisfies the equation. -- Root of a nail (Anat.), the part of a nail which is covered by the skin. -- Root of a tooth (Anat.), the part of a tooth contained in the socket and consisting of one or more fangs. -- Secondary roots (Bot.), roots emitted from any part of the plant above the radicle. -- To strike root, To take root, to send forth roots; to become fixed in the earth, etc., by a root; hence, in general, to become planted, fixed, or established; to increase and spread; as, an opinion takes root. "The bended twigs take root." Milton.

In deep grounds the weeds root deeper. Mortimer.

If any irregularity chanced to intervene and to cause misappehensions, he gave them not leave to root and fasten by concealment. Bp. Fell.

The Lord rooted them out of their land . . . and cast them into another land. Deut. xxix. 28.