There is a population of Rush skeletonweed at Heil Valley Ranch, a Boulder County Open Space park located west of Highway 36. This population has been managed effectively, but the Cal-Wood fire of October 2020 seems to have helped this plant proliferate. The seeds are easily transported by wind. If you are in the foothills north of Boulder, please be on the lookout and report sightings to EDDMapS immediately.
Rush skeletonweed is a native of Asia and the Mediterranean region. It is a herbaceous perennial that reproduces by seed and by an extensive root system. The wiry stems of the plant can grow from 1 to 4 feet tall. Stems are hairy from the ground up to 4 to 6 inches high with smooth stems above. These brown hairs are a distinguishing characteristic. Stems and leaves contain a milky latex if cut. The leaves on stems are sharply toothed. The hairless basal leaves are 2 to 5 inches long and 1/2 to 2 inches wide. Flowers are yellow and occur from mid-July to when frost occurs. Flower heads are less than 1 inch in diameter and consist of 9 to 12 flowers, although they may appear to be one. A vigorous mature plant can produce up to 1,500 flowers capable of distributing 20,000 seeds. Plants usually overwinter as rosettes which closely resemble common dandelion.
Watch aerial treatment video as a helicopter pilot uses GIS tracking software to treat rush skeletonweed at Heil Valley Ranch in Boulder County, Colorado.
Watch aerial treatment landing video as a helicopter pilot lands for a refill of herbicide.