Herbs mostly dioecious, rarely monoecious or polygamous. Rhizome scales imbricate, densely woolly pubescent. Stem simple or branched, terete, hollow except at nodes. Leaves usually closely appressed to stem, persistent; leaf sheath open, margin sometimes scarious, apex elongate; ligule usually absent; leaf blade absent. Inflorescences narrowly paniculate; spikelets very small, clustered, male ones pedicellate, female ones sessile, sometimes spicate; glumes subtending spikelets imbricate. Perianth segments 4--6 or sometimes indefinite, variously shaped. Male flowers: stamens (1 or)2 or 3; filaments ligulate to filiform, free; anthers dorsifixed, 1-loculed, introrse, apex apiculate; ovary (when present) rudimentary. Female flowers: staminodes 3 or absent; ovary superior, 1-loculed; styles usually 3, free or connate at base, free parts entirely stigmatic. Bisexual flowers: stamens 1--3; pistil 1. Fruit narrowly ellipsoid, ovoid, or obovoid; pericarp thin and opening on 1 side or thick and splitting at angles.

Four species: Cambodia, China, Indonesia (Aru Islands), Laos, Malaysia, New Guinea, Thailand, Vietnam; Australia; one species in China.