ARCTOPUS, in botany: A genus of the polygamia dioecia class; and in the natural method ranking under the 45th order, Umbellatae. The umbella of the male is compound; the involucrem consists of five leaves; the corolla has five petals; the stamina are five; and two pistilli: The umbella of the hermaphrodite is simple; the involucrem is divided into four parts, is spinous, large, and contains many male flowers in the disk. There is but one species of arctopus, viz. the echinatus, a native of Ethiopia.