Tufted annual. Leaves several to many, subulate to acicular, 1.5–5 cm long, 0.5–1.5 mm wide, translucent, 3–veined, fenestrate, tapering to a setaceous tip. Scapes up to 10, slender, slightly flexuous, often flaccid, 4–20(–40) cm high, 0.5–0.6 mm thick, 4–6–ribbed. Sheaths equalling the leaves, parallel–sided, obliquely slit. Capitulum subglobose with flattened base, 3–5 mm wide, white and grey, bracts loosely erect, the flowers visible between. Involucral bracts obovate–oblong to broadly oblong, 1.6–2.4 mm long, broadly obtuse, firm, yellowish with scarious grey or black margins and tip, in a single series subtending flowers, not reflexing at maturity. Floral bracts oblong to narrowly oblong, 1.6–2.5 mm long, obtuse to subacute, hyaline, lightly keeled below, concave, flushed grey or black with paler central band, glabrous or thinly white–pilose on the upper back, sometimes ciliate with short colourless hairs on the lower keel. Receptacle conical, glabrous or pilose. Flowers trimerous, pedicellate, mostly female. Male flowers: 1.3–2.3 mm long; sepals variably connate into a dark grey open spathe with tridentate upper margin, lateral sepals lightly keeled, free tips glabrous or white–pilose, a small median lobe present; petals on a slender, parallel–sided stipe, subequal, 0.2–0.6 mm long, white–pilose, glands prominent; anthers 6, creamy white. Female flowers: 1.6–3.0 mm long; sepals two, grey or black, narrowly oblong–navicular or falcate, 1.2–2.0 mm long, lightly keeled, sparsely ciliate with short colourless hairs on the keel, tips acute, glabrous or white–pilose; petals and ovary sessile or raised on a stipe to 0.3 mm long; petals 3, subequal, narrowly oblong–spathulate, median petal 1.2–2.3 mm long, all clawed, some colourless hairs on the blade; tips glandular, white–pilose. Seeds narrowly to broadly ellipsoid, 0.5–0.7 mm long, brown, faintly reticulate.
S. Zaire (Shaba Prov.), Tanzania (Mpanda Distr.), Zambia.
Shallow water of pans and pools on rock outcrops, or small dried–up waterholes in bushland; fl. & fr. Feb.– May; 1350–1800 m.
Best distinguished from other slender annuals by its pale anthers and seeds lacking obvious white papillae. Scape height is highly dependent on water level. Long flaccid scapes may be produced at first to reach the water surface, but much shorter erect ones appear later after the water has dried back.