in botany, a genus of the cryptogamia alga clas. The calyx of the male is peltated, and covered below with monopetalous corolla; the calyx of the female is scutate, bell-shaped, and contains many seeds. There are eight species, four of them natives of Britain, viz. the polymorpha, or common marchantia; the cruciata, or cross-headed marchantia; the hemispherica, or marsh marchantia; and the conica, or wort marchantia.