Annual wetland herb, 2–13 cm high. Leaves ± terete, often thread-like, smooth or scaberulous, 0.8–7 cm long, 0.4–0.5 mm diam.; basal sheath with acute to obtuse auricles to 0.5 mm long. Scape at fruiting erect or ascending, 0.6–13.5 cm long, to 0.25 mm diam. Infructescence a spike-like raceme, 0.3–2.5 (–5) cm long, 2.5–4.5 mm diam.; pedicels 0.25–0.65 (rarely to 3.5) mm long. Fruits c. 6–40 per infructescence, ellipsoid to ellipsoid-rectangular (excluding wings), 1–2.2 mm long, 0.7–1.2 mm diam. at midpoint. Carpels 6, 3 fertile alternating with 3 sterile, all united; mature fertile carpels dorsally convex but usually with a longitudinal groove, short-tapered at apex and base, and with two 2-pointed lateral wings, each carpel appearing 6-pointed when viewed dorsally; points bluntly triangular, to 0.6 mm long, rarely spinescent and then 0.7–2.2 mm long; wings and points sometimes near-absent; sterile carpels membranous with thickened dorsal edge, forming a conspicuous 3-winged central axis.
Occurs in damp to saturated, semi-saline, sand to clay soils of ephemeral lakes and floodplains, or rarely edging freshwater swamps.
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