Perennial herbs, often rhizomatous. Leaves submerged; basal sheath united to the leaf with the distal part forming a ligule, auricles absent; lamina linear; apex subulate to obtuse. Inflorescence a few- to many-flowered spike, submerged. Anthers 4; pollen ± spherical. Carpels 3–5; sessile. Fruit with inner hard tissue remaining.
About 8 species; 1 cosmopolitan species native to Australia and Victoria.