Cyperus L.
Culms distinctly 3-angular Cyperus
Style 2-fid. Nut compressed, biconvex or plano- or concavo-convex
Spikelets 6 or more flowered. Flowers falling from spikelet leaving persistent rhachilla, glumes falling away at maturity
Inflorescence terminal umbellate or capitate. Nut laterally compressed with one edge against the rhachilla
Spikelets narrow-oblong, 2–3 mm wide, 5–20 mm long, divergent. Glumes dark brown, red or black with pale margins. Loosely distichous, 1–3 mm wide. Inflorescence a simple umbel of 3–5 short rays or reduced to a head. Nut obovoid to globular, less than half as long as the glume. Perennial or apparently annual. Culms tufted or solitary. Widespread. Grassland and waste places Cyperus sanguinolentus
Spikelets narrow-linear, 1–2 mm wide. Glumes pale yellow to brown, green when immature, closely distichous. Tufted perennials or apparently annuals. Rhizome, when present, very short