Densely tufted. Culms erect, trigonous, smooth, longitudinally ribbed, 50–110 cm long, 2–3 mm diam. Leaves usually shorter than culms, 30–50 cm long, 3–6 mm diam.; sheath front transversely septate-nodulose, white hyaline often with indistinct pale brown spots; ligule 0–4 mm long, free limb to 0.2 mm long, apex emarginate to acute. Inflorescence narrow, erect, 3–5 cm long, compound with numerous short spikes, the individual spikes hardly recognisable; lowest involucral bract shorter or longer than inflorescence. Spikes sessile to subsessile, dense, closely aggregated, oblong to oblong-ovoid, 2–6 cm long, 1–1.5 cm diam.; spikes with male flowers above female flowers, hardly recognisable; female glumes ovate, apex acuminate, hyaline with light yellowish fawn margins and with green midstripe; female glumes 2.3–2.5 mm long, with awn 0.5–2 mm long; utricles 2.8–4 mm long, 1.5–2 mm diam., the base usually somewhat swollen with spongy tissue and rounded, elliptic to ovate, with (3–)5–7 dorsal nerves and (0–)3–5 ventral nerves, glabrous, yellowish brown to light brown, reddish brown distally; beak 1–1.5 mm long, with apex bifid, serrulate; style 2-fid. Nut lenticular, ovate, brown. Flowers in late spring and early summer.
GipP. Native to western part of the United States of America. In Australia known from a single 1999 collection where sparingly established at a very weedy site at Bungalook Creek, Bayswater North, Victoria. Several attempts to relocate the plants have been unsuccessful.
Superficially similar to a short-inflorescence form of Carex appressa, and to Carex incomitata, from which it is readily distinguished by its cross-rugulose leaf-sheath front (not to be confused with the transeversely septate-nodulose leaf sheath backs, present in all three species). Also superficially similar to species in section Ovales, which have gynaecandrous spikes.
