Cenchrus L. >
Inner involucral spines connate only at the base for up to a quarter of their length
Burr up to 7 mm long, usually purplish black when mature; bristles retorsely barbed. Spikelets usually 1 but up to 3 per burr. Tall or scrambling perennial usually with a knotted rootstock. Culms up to 2 m long or longer. Widespread. Open forests on poor soils. Fl. summer. Burr Grass Cenchrus caliculatus