Aquatic herb; stem filiform, branched, submerged, 0.5 mm broad. Submerged leaves sessile, narrowly linear, filiform, less than 3 mm broad with a well-marked lacunar band bordering the midrib; floating leaves 2-3.5 cm long, 6-7 (-10) mm broad, 5-7-nerved, ovate-lanceolate, long-petioled; petioles 1-2 (-2.5) cm long. Stipules free, open lanceolate-ovate, up to c. 1.2 cm long, 2-3.5 mm broad, membranous, caducous. Spikes few-flowered, globose, 1-1.5 cm long. Fruitlets obovoid, c. 1.5 mm long and almost equally broad, conspicuously beaked, often ornamented basally.

Fl.Per.: July-August.

Type: Cochinchina, Loureiro..

Distribution: A very distinct species, widely distributed in tropical and N.E. South Africa, Madagascar, S.E. Asia and N.E. Australia.