in botany, a genus of the tetradyamia siliqua clas. The pod is lanceolated, has two valves, and contains but one seed. There are four species, only one of which, viz. the tinctoria, or woad, is a native of Britain. It is used by the dyers. See Botany, p. 634.

ISCHÉMUM, SCHÖENANTH, in botany, a genus of the polygamia monoecia clas. The calyx of the hermaphrodite is a glume containing two flowers; the corolla consists of two valves; it has three stamina, two styli, and one seed. The calyx, &c. of the male are the same with those of the hermaphrodite. There are two species, both natives of the East Indies.