Actinomorphic or zygomorphic and unisexual. Inflorescence a head of tiny flowers borne at the apex of a scape. Subtended by an involucre of bracts. Fruit a loculicidal capsule. Seeds with endosperm present and mealy.
Placentation is basal.
Habit is as a perennial herb of shallow water or wet habitats. Leaves are simple, linear, narrow and grass-like and alternate or basal, often crowded. There is no sheathing at the base. Stipules are lacking.