Aquatic, mat-forming, brittle annual or perennial, up to 0.5 m long, forming submerged grass-like turf. Leaves opposite or upper ones ternate, linear. Flowers inconspicuous.
Submerged aquatic herb forming dense tangled mats, resembling fine grass; rhizome thin, branching freely; stems erect, to 50 cm long. Leaves 1–3 per node, ternate, opposite or alternate, greenish brown, subterete or linear, 1.2–5 cm long, 0.5–2 mm wide, at base with or without tubular, membranous sheath, at apex attenuate; axillary scales minute. Flowers almost consistently 1 and a cluster of together at each pseudowhorl or distally sometimesalone, each surrounded by a membranous sheath; staminate flower of a single stamen, filament elongating at anthesis, to 2 cm long, anther 4–8-locular, at base with small axial protuberance, at apex with gland; pollen glandular; pistillate flowers (1–)4–5(–8) in pseudo-umbel, when immature enclosed in cupular sheath, peduncle 1–5 mm long, carpel ovoid, stipitate, stigma spoon-shaped but rapidly disintegrating. Fruit reniform, 2–6 mm long, with a keel and protuberances on convex and sometimes concave sides, stipitate, with persistent style.
Tanzania Ngare Nanyuki R. near market, Jan. 1971, Richards & Arasululu 26610!
Tanzania Ngorongoro Crater, Gaitokitok Springs, Nov. 1956, Greenway 9061!;
Tanzania Titushi R., Apr. 1961, Greenway 10100!;
Northern, central and southeastern Namibia, Eksteenfontein, Calvinia, Cape Peninsula to Port Elizabeth through to Free State and Gauteng, ± cosmopolitan.
Sp. Pl.: 969 (1753); Bennett in F.T.A. 8: 225 (1901); Oberm. in F.S.A. 1: 77 (1966); Dandy in Fl. Iraq 8: 29, t. 11 (1985).