Not Known To Occur In Colorado
Common crupina is an erect winter annual growing one to three feet in height. The leaves are alternate, finely dissected, and develop short, stiff spines along the edges. Flowers are pink to purple in color and grow one to two on a branch with each plant having several branches and up to 40 flowering heads per plant. Flowers protrude through a whorl of stiff bracts. Seeds are 1/8 to 1/4 inch long with barbed hairs at one end. Common crupina spreads by seed by attaching itself to livestock, wildlife, and people and floating down rivers and streams.