Annual herb. Stems simple or branched, sometimes creeping and rooting at nodes, erect above, to 15 cm high. Leaves decussate or in whorls of usually 3, sessile, to 12 mm long; aerial leaves elliptic to lanceolate, ovate to linear; submerged leaves usually whorled, linear. Bracts similar to terrestrial leaves or obovate, to 10 mm long, obtuse; bracteoles bract-like, usually herbaceous, often partly enclosing flower, usually 2-3 times as long as hypanthium. Hypanthium sub-urceolate, to 1 mm long; appendages absent. Sepals 5, broadly triangular, to 0.5 mm long. Petals absent. Stamens 3, rarely 4, inserted near base of hypanthium. Style to 0.5 mm long. Capsule ellipsoidal, c. 1.5 mm long, opening by 3 valves.
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