CERATOPHYLLUM, in botany, a genus of the monocardia polyandria class. The calix of the male is divided into many segments; it has no corolla; and the stamens are from 16 to 20. The calix and corolla of the female are the same with those of the male; it has one pistil, no stylus, and one naked seed. There are two species, one of which, viz. the demersum or horned pondweed, is a native of Britain.