Perennial scapigerous herbs of wet habitats, rhizomatous; rhizome short, with fibrous roots. Leaves basal or cauline, sheathing at the base, linear, ensiform or flat and dilated, entire, often tapering above. Inflorescence fascicled umbellate cymes, terminal; involucre with 2 or 3 bracts. Flowers 3-merous, hermaphro¬dite, actinomorphic, usually long pedicelled. Perianth 2-seriate, persistent, the outer 3 sepal-like, imbricate, shorter than the inner whorl of 3 petal-like, imbricate segments, usually thin and deciduous, rarely absent. Stamens usually 6-9, rarely 5 or numerous, very variable, outer usually sterile; filaments flattened or linear, short or long, free, hypogynous; anthers basifixed, 2-celled, ovate to oblong, longitudinally dehiscent, introrse. Carpels (3-) 9 (or many), superior, whorled, free or basally connate, sessile on a flat receptacle; styles very short, terminal on each carpel; ovules numerous, anatropous, scattered on branched reticulate, parietal placentas. Fruit of 6-many seeded follicles, each follicle free or nearly so, opening by the ventral side. Seeds minute, smooth, exalbuminous; embryo straight.