ACNIDA, VIRGINIAN HERB, in botany, a genus of the diœcia order, belonging to the pentandria class of plants; and, in the Natural Order, associating with the Seabrides (53). The characters are: In the male, the calyx is a perianthium consisting of five leaves, ovate, concave, acute, and membranous on the margin. No corolla. The stamina consist of five very short capillary filaments; the antheræ are versatile, two-celled, and forked at both ends.—Female on a separate plant; of which the calyx consists of an involucrum many-leav'd, linear, and deciduous; and a perianthium two-leaved, very small, and persistent. No corolla. The pistillum has an ovate germ; the styli are five, long, reflected, and downy; the stigmata are simple. The pericarpium is an egg-shaped fruit, compressed, many-angled, sulcated, and covered with a succulent calyx. The seed is solitary, round, and compressed. There is only one species of it, viz. the acnida cannabina. It is a native of Virginia; but rarely cultivated in Europe, except for the sake of variety. It has little beauty, and at present is applied to no useful purpose.