ARISTIDA, in botany: A genus of the triandria digynia class; and, in the natural method, ranking under the 4th order, Gramina. The calyx has a double valve; the corolla has one valve, and three awns at the points. There are three species of aristida, viz. the ascensionis, a native of the island of Ascension; the Americana, a native of Jamaica; and the plumosa, a native of America.