Tufted perennial, often prostrate or drooping, from a slender ascending rhizome c. 0.5 mm in diameter. Culms 3-30 cm × 0-5-1 mm; 1-2 basal bracts per culm, membranous, grey-brown or sometimes red-purple. Leaves (l)-2-3-(4) per culm, shorter than or equalling culms; sheath often streaked with red-purple. Inflorescence c. (3)-4—5 mm high and (3)-5-9 mm broad, usually almost semicircular in outline, of 2—5 ovate, obtuse, closepacked spikelets, each usually dark red-purple, almost black below and green above to grey-brown later, rarerly entirely grey-green; subtending bract much exceeding inflorescence, up to 10 cm long, rigid, as wide as a foliage leaf, red-purple at base, sometimes a second shorter subtending bract is present. Glumes 2—2-5 mm long, lanceolate, acute, membranous, tinged with redpurple, keel very thick, green, slightly excurrent. Stamens 3 in lower glumes, to 2-1 above. Style branches 3. Hypogynous bristles 0. Nut about half the length of the glume, c. 1 × 0-5 mm, trigonous, with angles slightly thickened, elliptical, smooth, pale cream, shortly stipitate and apiculate.

Herba perennis spissis foliis, stolonifera. Culmi 3—30 cm long, subflaccidi. Folia breviora culmis vel eis aequantia; vagina saepe purpureo colore tincta. Spiculae 2—5, prope in formam semicirculi dispositae, compactae, rubro-purpureae basi, glaucae supra, vel rarissime glaucae per totam spiculam; bractea subjacens inflorescentiam longitudine multo superans, basi rubro-purpurea. Glumae lanceolatae, acutae, purpureo colore tinctae; Carina crassa, viridia. Stamina 3 in glumis inferioribus, in superioribus 2-1. Styli rami 3. Setae hypogynae 0. Nux c. dimidium glumae, trigona, laevis, pallida.

Thick tufts. Stems rather lax, 3-30 cm high. Leaf sheaths usually dark red-purple. Inflorescence ± semicircular in outline, of 2-5 spikelets, almost black at base, lighter green at tips, with long rigid bract. Stamens 2-1. Style-branches 3. Nut trigonous, cream.

Thickly tufted, often prostrate or drooping, from a slender ascending rhizome c. 0.5 mm. diam. Culms 3–30 cm. × 0.5–1 mm., rather lax; 1–2 basal bracts per culm, membr., grey-brown or sometimes red-purple. Lvs (1)–2–3–(4), < or ± = culms, < 1 mm. wide, sheath often streaked with red-purple. Infl. apparently lateral, c. (3)–4–5 × (3) –5–9 mm., us. almost semicircular in outline, of 2–5 ovate, obtuse, close-packed spikelets; subtending bract much > infl., up to 10 cm. long, rigid, as wide as a foliage lf, red-purple at base, occ. a second shorter bract present. Spikelets deep red-purple, almost black, at base, distally green at first but turning grey-brown; at times entirely grey-green. Glumes 2–2.5 mm. long, lanceolate, acute, membr., tinged with red-purple, keel very thick, green, slightly excurrent. Hypog. bristles 0. Stamens 2–1, rarely 3 in lower glumes. Style-branches 3. Nut c. 1 × 0.5 mm., c. ½ length of glume, trigonous with angles slightly thickened, elliptical, smooth, pale cream, shortly stipitate and apiculate.