Cyperus eragrostis Lam.

Rhizome short, thick, woody. Stems 25–90 cm high, stout, obtusely trigonous, smooth, leafy and ± thickened at base. Leaves usually < stems, 4–8 mm wide, flat, margins finely serrate; sheaths dark purple-brown. Involucral bracts 5–8, leaf like, unequal, often very much > inflorescence. Inflorescence a compound umbel, rather variable in size; rays 5–7–(9), of unequal length, each with a dense pale green to yellow-green globose or hemispherical spike at tip, 1–2 cm diam. Spikelets many, densely crowded, much compressed, ± 5–12 ×3 mm, ovoid-oblong, subacute. Glumes many, ± 2 mm long, densely imbricate, ovate, membranous, cells very distinct, whitish-cream to light brown, 1-distinct lateral nerve on each side, keel green, tip slightly recurved. Stamen 1. Style-branches 3. Nut ± ½ length of glume, trigonous, obovoid brown.

[From: Healy and Edgar (1980) Flora of New Zealand. Volume 3.]