Cenchrus longispinus is an annual grass with conspicuous burs along the seedhead. Sheaths may reach 20 in. (51 cm) in height. C. longispinus stems are somewhat flattened and hairless and has a fibrous root system. C. longispinus is native to North America, Mexico and South America.
Foliage
C. longispinus leaves may reach 8 in. (20.3 cm) in length and 0.24 in. (6 mm) in width. The upper surface is rough and there are no hairs on the lower surface. The ligule is a fringe of hairs and is about 0.04 in. (1 mm) long.
Flowers
The inflorescence of C. longispinus is a terminal, spikelike panicle of fascicles or burs. The fascicles have sharp bristles that surround and can conceal 1-4 spikelets. The spikelets are sessile, with 2 florets.
Fruit
Fruits are contained in the spiny burs held along the terminal panicle. Each bur is somewhat hairy and is approximately 0.2-0.3 in. (5-7 mm) wide.
Ecological Threat
Cenchrus species are typically found in sandy sites, abandoned fields, and recently disturbed areas. They invade recently disturbed areas and can tolerate a wide range of soil types and moisture conditions, allowing it to compete successfully with other species.