Annual wetland herb, 2–11 cm high. Leaves ± terete, 1–5 cm long, 0.5–0.8 mm diam.; basal sheath with fine acute auricles 0.7–1.6 mm long. Scape at fruiting erect or ascending, 0.7–6.2 cm long, 0.5–1.1 mm diam. Infructescence a spike, 1–3 cm long, 1.5–2.5 mm diam.; pedicels absent or minute. Fruits (1–) 4–12 per infructescence, semi-erect, the body narrowly obovoid, expanded at base into widespreading spines, 6.1–10.3 mm long, 1–1.4 mm diam. at widest part (excluding spines), seated on a thickened receptacle c. 0.6 mm long. Carpels 6, 3 fertile alternating with 3 sterile, all united; mature fertile carpels not readily separating, with dorsal surface strongly rounded in T.S.; basal spines 2 per carpel, directed laterally to somewhat downwards but shallowly upcurved, acute, the dorsal edges thickened and raised, the ventral edges more membranous and sunken and flanged onto receptacle; spines 2.2–3.9 mm long; central axis almost obscured by the much wider fertile carpels.
Grows on damp, winter-wet, sandy-clay, saline soils of flats, claypans and lake edges.
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