Stout perennial aquatic herb. Stems to 75 cm long. Leaves: submerged leaves in whorls of 5 or 6, ovate, pectinate, with 25–35 pinnae, lamina 4–6 cm long; emergent leaves whorled or irregular, linear to narrowly oblanceolate, with 10–12 short distal teeth, lamina 15–22 mm long. Bracteoles lanceolate to ovate, 0.8–1.4 mm long, with 2 or 3 teeth. Flowers bisexual, 4-merous, sessile, solitary. Sepals orbicular, 0.3–0.4 mm long. Petals 2–2.4 mm long, persistent, yellowish pink. Stamens 8. Ovary 4-locular, sharply angled; styles short; stigmas pale pink. Fruit depressed-globular, 4-winged; mericarps rounded, laterally flattened, with dorsal wing, 2.4–3 mm long, 1.7–2.4 mm wide; endocarp spinous, supporting an inflated exocarp.
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