Herbs, annual or perennial, cespitose or not, rhizomatous or not. Culms solitary or not, trigonous. Leaves basal; ligules absent; blades flat or V-shaped in cross section. Inflorescences terminal, rarely pseudolateral, spikes 1-4, sessile, densely ovoid or cylindric; spikelets [15-]40-150 per spike, not readily distinguished by unaided eye; involucral bracts 2-4, spreading or erect, leaflike. Spikelets: scales 2(-3), distichous; proximal scale subtending bisexual flower; distal scale empty or subtending 1-2 stamens, often abortive. Flowers bisexual or staminate; perianth absent; stamens 1-3; styles linear, 2-fid, base persistent. Achenes biconvex, laterally compressed.

Tropical Africa contains the greatest diversity of Kyllinga species.

The genus is closely related to Cyperus and has been treated as a subgenus.