Rhizomatous, aquatic herb, nearly glabrous, floating. Petioles 15-50 cm long; blades suborbicular, blunt to rounded at apex, subcordate (the sinus 1-5 cm deep), 5-15 cm long, 3-10 cm wide, entire, green below. Flowers long-pedunculate, floating on water, opening at night, mostly 7-9 cm broad; sepals 4, lanceolate-ovate to acute, 3-5 cm long, green outside, greenish-white inside; petals to 14, lanceolate-oblong, acute at apex, white, the outermost often tinged with green at apex, about as long as sepals, the innermost much shorter; stamens numerous; flattened, 1-2.5 cm long, arched inward, the outermost thicker and longer, gradually reduced in length inward; anthers introrse, comprising about half of stamen, the connective rounded at apex; carpels ca 20, connate laterally, the entire unit to 1.2 cm diam. Fruits 1.5-2.5 cm broad, l-2 cm long, maturing under water, pulpy, irregularly dehiscent; seeds many, globose, operculate, ca 1.5 mm long, strigillose. Croat 12232.