Herbs, perennial, cespitose, rhizomatous. Culms distally branched, terete. Leaves basal; ligules absent; blades involute or subcylindric. Inflorescences terminal, sometimes pseudolateral, capitate [diffusely branched]; spikelets (1-)10-25, black or very dark purple; involucral bracts 1-2, spreading or erect, leaflike. Spikelets: scales 3-8, distichous, black or very dark purple, 2-3 proximal scales empty, distal scales each subtending flower. Flowers bisexual; perianth bristles 0-6, shorter or longer than achene, smooth or scabrous; stamens 3; styles deciduous, linear, 3-fid. Achenes rounded-trigonous to subterete.

Schoenus is restricted mostly to Australasia; a few species occur in Africa, Eurasia, and the New World.