Flowers just above water-level, yellow or white (dried specimens always appear to be yellow).
Sepals linear to linear-lanceolate or linear-oblong, 0.65–1.37(–2) cm. long, 1.6–5.3 mm. wide, acute to obtuse, whitish or green, often with brown longitudinal striations, the margins hyaline.
Petals obovate, 1.2–2.3(–3) cm. long, 0.8–1 cm. wide, rounded or somewhat truncate, white, white with yellow base, or yellow.
Stamens 3–6; anthers 1.5–2.3 (–3) mm. long, yellow; filaments up to 6.5 mm. long.
Ovary of 3–6 carpels, narrowly ellipsoid, 1–1.8 cm. long 0.3–0.4 cm. wide; perianth-tube up to 0.7 cm. long; styles 3–6; stigmas 6–12, up to 20 mm. long, yellowish.
Stems erect, corm-like, simple or rarely forked.
Fruit narrowly ellipsoid to ovoid or cylindric, 2–4 cm. long, 1–1.3 cm. wide, green, opening by decay of the pericarp.
Hermaphrodite, annual, rarely perennial.
Seeds narrowly cylindric, 2.1–2.5 mm. long, 0.5–0.7 mm. wide, dark brown.
Mature leaves petiolate; blade submerged or floating, linear-elliptic to ovate-elliptic, 8–45 cm. long, 0.9–11.5 cm. wide, acute to obtuse, cuneate at base, smooth, light to mid-green, with 5–13 prominent longitudinal veins connected by cross-veins, together with many smaller longitudinal veins; margins entire; petiole 6.2–100 cm. long, 0.2–0.8 cm. wide.
Spathe: peduncle 4.2–60 cm. long, 0.3–0.7 cm. wide; body of spathe submerged, not or slightly inflated, linear-oblong, elliptic, ovate or urceolate, 2–5.6(–6) cm. long, 0.4–2.7(–2.8) cm. wide, 2–6-lobed at the apex, with 0–2 wings and several longitudinal ribs or veins, green, somewhat translucent.
Aquatic herb. Leaves all submerged, lanceolate, tapered at base, margin entire, undulate. Monoecious. Flowers bisexual. Flowers yellow or cream.
Monoecious. Leaves all submerged, in rosettes, crowded, radical or on petioles, thin but firm, variable in size and shape, linear-lanceolate to ovate-lanceolate, up to 23 cm long and 5 cm broad, attenuate above and below, margin wavy, entire or sparsely denticulate. Inflorescence on a peduncle which is triangular in cross-section, up to 23 cm long and 3 mm in diam.; spathes saccate, compressed, narrow-ovate in outline, becoming much broader in fruit, up to 4 cm long and 2 cm broad, green with brownish nerves, narrowly winged, orifice with a few irregular small teeth; flowers bisexual; perianth-tube just exserted from spathe, outer segments linear-oblong, 8 mm long and 2 mm broad, green, inner obovate, 25 mm long and 9 mm broad, yellow or cream, with a small gland at the base; stamens 6, filaments flattened, 4 mm long, anthers small; ovary 17 mm long and 4 mm broad, placentas 6, unequal, styles 6 with 2 short stigmaticrarms. Fruit enclosed in the spathe, seeds small, cylindrical, covered with fine white hairs.