Robust aquatic herb, dioecious, rarely monoecious. Stems 1 m or more long. Leaves in whorls of 2 or 3; submerged leaves ovate, pectinate, with 10–12 pinnae, lamina 1–2 cm long; emergent leaves linear, oblanceolate or obovate, serrate in distal half, lamina 2–4.5 cm long. Bracteoles oblong to lanceolate, 1–1.2 mm long. Flowers 4-merous, sessile, males solitary, females in fascicles of 1–3. Male flowers: sepals lanceolate, 1 mm long; petals 3.3–3.7 mm long, persistent; stamens 8. Female flowers: sepals minute, deltoid; petals absent; ovary 4-locular, each carpel with sharp dorsal angle; styles filiform, 0.6 mm long; stigmas fimbriate on upper surface only, white. Fruit unknown, possibly 4-winged.
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