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
Spikelets 1-4 flowered. Rhachilla articulate above the 2 lowest sterile glumes, spikelet falling away as a unit at maturity leaving a knob or protuberance on the rhachis. Inflorescence a dense globular to ovoid or cylindrical capitate spike