Native to the Rocky Mountain region, and found widely in the western United States, particularly on over-grazed lands. It also occurs on waste areas and along roadsides.
An annual weed that is covered with sharp, stout spines that make it unpalatable for grazing. The entire plant contains a yellow sap, and some people suffer skin irritation from contact with the spines.
Mature plants grow to 3 feet tall, with a one or more stems and sparse branching at their upper length. Leaves form alternate along the stem, and are up to 10 inches long, grayish-green, deeply lobed, and spiny along all the margins as well as the mid-rib.
Flowers are large and showy, up to 3 inches across, white with a distinct yellow center of stamens, and occur in clusters of 3 to 6 at the ends of erect stems at the top of the plant.
Characteristicts Important to Control:
An annual weed of minor importance.