Annual or perennial acaulescent aquatic herbs with submerged corm or rhizomatous stem. Leaves alternate, simple, floating, cordate, peltatc, linear to orbicular with sagittate to cordate base, long petioled. Flowers solitary, usually large. Sepals 4, adnate to ovary, usually green. Petals many, often gradually passing into staminodes and stamens. Stamens many (20-700), free or adnate to the petals. Carpels 8 or more, syncarpous or partially united, ovary superior to subinferior, many-Jocular, stigmas separate or united into a disc with radiating rays. Fruit a many seeded, irregularly dehiscent, berry. Seeds with or without aril.