Leaves varying greatly in size, up to 20 cm wide, submerged or partly emersed, broadly ovate to lanceolate, subcordate to cuneate at the base, 7- to 11-veined. Spathes with 5-10 longitudinal wings. Petals 20-30 mm, obovate, white, with a yellow spot at the base. Stamens 6-9. Styles 6-9.
Rootstock perennial. Acaulescent. Leaves with long triquetrous petioles, broadly cordate, obtuse, 7–11-nerved, 4–6 in. wide. Flowers solitary on peduncles 6 in. to 1 ft. long, hermaphrodite. Spathe closely applied to the ovary, 3–6-toothed and winged. Calyx-lobes oblong, 6 lin. long, 1 1/2 lin. wide. Petals 3, broadly ovate, shortly unguiculate, white, 1 in. long. Stamens 6–10; anthers linear, slightly shorter than the filaments. Ovary oblong, divided more or less completely into 6 cells by the intrusion of the placentas; ovules numerous; styles 6, linear, bifid.
Monoecious, dioecious or hermaphrodite, annual or perennial. Stems corm-like, simple or rarely forked. Juvenile leaves linear to obovate or spathulate. Mature leaves petiolate; blade submerged or floating, elliptic to widely ovate, 8–17 cm. long, 5.7–20 cm. wide, acute to obtuse or rounded, cuneate to cordate or somewhat involute at base, smooth, with 2–10 prominent longitudinal veins connected by cross-veins, together with many smaller longitudinal veins; leaf-margins entire or denticulate. Nodal scales 4–10 per leaf, ovoid to conical. Spathe: peduncle 10–50 cm. long, 0.17–0.5 cm. wide; body of spathe submerged, sometimes slightly inflated, cylindric to ellipsoid or urceolate, 2–6-lobed at the apex, with 3–12 crisped or wavy wings or ribs. Male flowers several per spathe, with pedicels up to 7 cm. long; ♀ and hermaphrodite flowers sessile. Sepals narrowly triangular to ovate, 0.6–2.4 cm. long, 1.8–5.7(–9) mm. wide, subobtuse to rounded, green, the margin often hyaline; petals ovate to orbicular, 1.8–3 cm. long, 0.5–1 cm. wide, rounded or obcordate, white, white with yellow base, yellow, pink to purple; stamens 3–12; anthers 2.5–4.5 mm. long, yellowish; filaments up to 6 mm. long; staminodes filiform or 2-lobed, up to 4.8 cm. long; ovary of 3–10 carpels, narrowly ellipsoid, 0.7–2.2 cm. long, ± 0.7 cm. wide; perianth-tube 0.6–0.8 cm. long, styles 3–10; stigmas 6–20, up to 6 mm. long, yellowish. Fruit ellipsoid to ovoid, rarely cylindric, 1.5–4(–5) cm. long, 1–2 cm. wide, opening by decay of the pericarp. Seeds narrowly cylindric, 0.9–1.3 mm. long, 0.3–0.5 mm. wide, dark purple to black, with longitudinal striations.
HAB. Still or moving water up to 1 m. deep; 1050–1110 m.