Leaf

n.; pl. LEAVES. [O. Eng. leef, A-S. leaf, O. Sax. lōf, lōbh, O. Fries. laf, D. loof, Icel. lauf, Sw. löf, Dan. löv, Goth. laufs, O. H. Ger. loup, N. H. Ger. laub, allied to Lith. lāpas.]

1Sense 1. (a.) (Bot.) One of the three principal parts or organs of vegetation. It is developed by increase at its base from and about the stem, and has a definite shape and limited growth.

☞ Leaves perform various functions, as cotyledons, scales, spines, tendrils. Every part of a plant that is not stem is leaf.

(b.) That form of such an organ having a flattened shape and greenish color, and in which the descending sap is elaborated for the nutrition of the plant.

☞ Such leaves usually consist of a blade or lamina, supported upon a petiole or leaf-stalk, which, continued through the blade as the midrib, gives off woody ribs and veins that support its cellular texture. The petiole has usually some sort of an appendage on each side of its base, which is called the stipule. The green parenchyma of the leaf is covered with a thin epiderm pierced with closable openings, known as stomates.

Leaf.

b. blade; p. petiole, foot-stalk, or leaf-stalk; st. stipules.

2Sense 2. Something which folds, bends over, or otherwise resembles a leaf; as, (a.) A part of a book containing two pages. (b.) A side, division, or part, as of window-shutters, folding-doors, &c. (c.) The movable side of a table. (d.) A very thin plate; as, gold leaf. (e.) A portion of fat lying in a separate fold or layer. (f.) One of the teeth of a pinion, especially when small. (g.) (Arch.) An ornament resembling, or made in imitation of the leaves of certain plants or trees, as those of the laurel, palm, acanthus, &c. [See Illust. of Leaves.]

Compound leaf (Bot.), a leaf having more than one blade attached to the same petiole.