Herbs, perennial, to 45 cm, arising from stout, tuberous rhizomes, stolons present, corms present. Root depth, minimum 0.45 cm (USDA-NRCS, 2009). Leaves erect, those submerged, if present, linear and ribbon-like, emersed ones with blades sagittate, lateral lobes as long as terminal one, linear or ovate-deltate, 2-20 cm long, 0.5-12 cm wide, terminal lobe deltate to ovate-deltate or linear, 3-25 cm long, 0.7-35 cm wide, apex acuminate to subobtuse, petioles 20-70 cm long. Inflorescences racemes, rarely panicles, of 3-9 whorls, emersed, 4.5-28.5, (4-23) cm, peduncles 10-59 cm, bracts connate more than or equal to 1/4 total length, elliptic to lanceolate, 3-8 mm, delicate, not papillose, fruiting pedicels spreading, cylindric, 0.5-3.5 cm. Flowers to 4 cm diameter, unisexual (and the plants monoecious or dioecious), lower flowers pistillate, upper ones staminate, and usually with some perfect flowers in the middle, or rarely all flowers perfect, scapes few, 15-70 (-90) cm long, shorter than or slightly longer than leaves, each with 2-7 verticils of flowers, pedicels 0.5-6 cm long, bracts 2-3 per flower, papery, lanceolate to deltate, 0.5-1 (-1.5) cm long, usually gibbous, sepals ovate, 5-10 mm long, petals white, very broadly elliptic, 1-2 cm long, abruptly narrowed into a claw.