Perennial or sometimes annual, grass-like, usually tufted herbs, commonly growing in moist places. Inflorescence usually compound or decompound, paniculate, corymbose, or umbelloid, rarely reduced to a single flower, bearing its flowers singly, or loosely clustered, or aggregated into spikes or heads. Flowers small, regular, with or without bractlets (prophylla). Perianth 6-parted, the parts glumaceous. Stamens 3 or 6, rarely 4 or 5, the anthers adnate, introrse, 2-celled, dehiscing by a slit. Pistil superior, tricarpous, 1-celled or 3-celled, with 3-many ascending anatropous ovules, and 3 filiform stigmas. Fruit a loculicidal capsule. Seeds 3-many, small, cylindric to subglobose, with loose or close seed-coat, with or without caruncular or tail-like appendages.

Eight genera and about 300 species, widely distributed.