Description from Flora of China
Herbs, perennial, aquatic or of swamps, rhizomatous, usually with milky juice. Leaves usually emersed, basal, alternate, linear to orbicular, sheathing at base, sessile, triquetrous. Flowers hermaphroditic, in terminal, long pedunculate umbels within erect scapes, long pedicellate, with 3 free bracts. Perianth segments in 2 series, outer 3 usually sepal-like, inner 3 petal-like and usually thin and deciduous. Stamens 9, free; anthers basifixed, 2-celled, opening by longitudinal slits. Carpels 6, connate at base; ovules numerous. Fruit a whorl of follicles; follicles with apical long beak. Seeds numerous, without endosperm; embryo straight.
Zhou Lingyun. 1992. Butomaceae (excluding Butomopsis and Limnocharis). In: Sun Xiangzhong, ed., Fl. Reipubl. Popularis Sin. 8: 146-147.
One genus and one or two species: best represented in tropical areas of the Americas, also in S Africa, Asia, Europe, and North America; one species in China.
(Authors: Wang Qingfeng (王青锋); Robert R. Haynes, C. Barre Hellquist)