Perennial, aquatic herb, stemless, erect with thick, stoloniferous rhizome; mature leaves with very long, trigonous petiole, hastate or sagitate, acute or acuminate at apex, young ones floating; scape 15-45 cm long with whorls of 3-5 unisexual or polygamous flowers, each about 1-2 cm across; bracts small, ovate, obtuse; sepals-3, herbaceous; petals-3, membranous, deciduous, white, usually with purple claw; lower whorls female, nearly sessile; upper male, with longer pedicels; stamens-6 or more, filaments filiform, compressed; carpels many, free, crowded on a large, globose or oblong, laterally flattened receptacle; ovary 1-celled, stipitate or sessile, style short, ventral or apical, stigma papillose, ovule solitary; fruit globose, head of small, flattened, crested or winged achenes, each obliquely obovate, flat, dorsally winged; seeds erect.