In Idaho the weed is widely dispersed. Each plant produces up to 25,000 seeds that are dispersed by wind, animals, and people. Seeds may remain viable for 8 years. Mature plants may be 3 feet in height and are much branched. The weed forms a basal rosette the first year and stem leaves are pinnately divided.
Flower heads are abundant, inch wide, and generally solitary on branch tips.
Flowers are pink to purple, or occasionally white, and appear from midsummer to fall. Each stiff flower head bract has a dark comblike fringe resembling a black spot at the tip. Seeds are dark brown to tan and are tipped by plumes that fall off at maturity. A seed head moth and 2 seed head gall flies have been effective.