Small water plants, floating at the surface. Inflorescence 1, lateral, developing from one of the budding pouches, consisting of 1 ♀ and 2 ♂ flowers, enclosed by a membranous spathe. Fruit asymmetric, slightly or distinctly winged. Seed smooth or longitudinally ribbed.
Arctic regions absent, worldwide present
Worldwide, the Arctic regions excepted, consisting of 4 spp.