蒺藜草（学名：Cenchrus echinatus）为禾本科蒺藜草属下的一个种。

Cenchrus echinatus is a species of grass known by the common names southern sandbur, spiny sandbur, southern sandspur, and in Australia, Mossman River grass. It is native to North and South America.

It is a clump-forming annual grass growing up to 80 cm tall. The leaves occur with or without hairs and measure up to 12 mm wide. The ligule is a fringe of hairs. The grass has barbed burrs up 4–10 mm long.