Buffalobur is native to the American southwest where it evolved to grow in the highly disturbed areas caused by the buffalo wallows. The leaves have large, rounded lobes and are spiny, particularly on the lower midrib. The flowers are yellow with 5 petals forming a tube about 1 inch broad. One of the anthers is much longer than the other four. The fruit is a somewhat spherical, spiny capsule. Buffalobur has spread to virtually every state in the U.S. as a contaminant in seed.