Herbs, annual or perennial, to 100 cm; rhizomes present; stolons present; corms present. Leaves submersed and emersed; submersed leaves absent or phyllodial, flattened, to 17 ´ 2 cm; emersed leaves with petiole triangular, 21--55 cm, blade hastate to sagittate, 2.5--17.5 ´ 0.6--22 cm, lobes longer than or equal to remainder of blade. Inflorescences racemes or panicles, of 1--15 whorls, floating or emersed, 1.5--28 ´ 1.5--15 cm; peduncles 15--47 cm; bracts distinct or connate less than ¼ total length, lanceolate to elliptic, 4--34 mm, delicate, not papillose; fruiting pedicels recurved, club-shaped, 0.5--4.2 cm. Flowers 2--5 cm diam.; sepals spreading in staminate, erect in pistillate, enclosing flower or fruiting head; filaments cylindric, longer than anthers, glabrous; pistillate pedicellate, with or without ring of sterile stamens. Fruiting heads 1.2--2.1 cm diam.; achenes oblanceoloid, not abaxially keeled, 2--4.3 ´ 0.7--1.5 mm, beaked; faces not tuberculate, wings absent, glands 1; beak lateral, horizontal, 0.4--0.8 mm.