Cyperus difformis L.

Spikelets obtuse, very numerous in dense globular clusters on each umbel ray, only slightly compressed, 4–8 mm long, 1 mm wide, 10–40-flowered. Glumes 0.8 mm long, very obtuse. Nut c. as long as the glume. Culms up to 50 cm high. Annual. Widespread. Weed in damp place throughout the warmer parts of the world