any of a genus (Cenchrus) of grasses, having their grains enclosed in spiny burs
See sandbur in American Heritage Dictionary 4
(săndˈbûrˌ)
noun In both senses also called sandspur.
Any of several grasses of the genus Cenchrus, especially C. tribuloides, of the eastern United States and tropical America, having a spiny burlike envelope that surrounds several one-grained spikelets.