Rhizomatous aquatic perennial herb with submerged and floating leaves. Stem terete, to 3 m long; turions not recorded. Stipules convolute, free from base of leaf blade. Submerged leaves petiolate; blade lanceolate, 7.5–15 cm long, 1–3 cm wide, tapered at apex and base, translucent, 7–15-veined. Floating leaves petiolate; blade lanceolate, 5–9.5 cm long, 1.5–3.5 cm wide, tapered at base, acute or obtuse at apex, coriaceous, 10–21-veined. Inflorescence a terminal spike, emergent, dense, to 5 cm long. Peduncles erect, recurved when fruiting. Fruit 3–5 mm long (including beak), keeled with prominent beak, reddish, brownish or green.
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