Annual or perennial herbs. Leaves usually in a basal rosette, mostly with 3–9 longitudinal veins. Inflorescences cylindric spikes to globose heads or rarely flowers solitary; bracts usually membranous. Flowers bisexual; sepals more or less membranous with a prominent keel, persistent in fruit; corolla scarious or membranous; stamens hypogynous, anthers usually much exserted on thread-like filaments, with a terminal appendage; ovary superior, usually 2-celled but sometimes 3- or 4-celled by the growth of false septa, ovules mostly 1–6 per cell, style thread-like, stigma papillose. Fruit a circumscissile capsule; seeds 1–16, usually with a mucilaginous coat.
About 265 species, cosmopolitan but mostly in temperate regions; 34 species (10 introduced) in Australia.