Plants perennial, submerged. Rhizome branched, terete, 1-1.5 mm in diam., with apical dormant buds. Stems moderately branched at base. Stipules partly fused with leaf base and sheathing stem; sheaths 0.6-4 cm, on vegetative branches 0.8-3.5 mm in diam., herbaceous, connate, tubular toward base at least when young, appearing as a closed ellipse when transversely dissected, persistent; leaves sessile, filiform, 5-10 cm × 0.7-2.4 mm, 3-veined, apex obtuse to rounded. Spikes terminal, with 4-6 whorls of opposite flowers, lowermost whorl shortly distant from upper whorls; peduncles filiform, 1-22 cm. Carpels 4. Fruit (2.7-)2.9-3.3 × ca. 2 mm, abaxial keel indistinct, obtuse, beak recurved. Fl. and fr. Jul-Oct.
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