> Departments > Natural Resources > Weed Control District >Musk Thistle  

Musk Thistle (Carduus nutaans)

Musk thistle is a member of the Aster family, Thistle tribe. It is an introduced biennial, winter annual, or rarely annual which reproduces by seed. The first year's growth is a large, compact rosette from a large, fleshy, corky taproot. The second year stem is erect, spiny, 2 to 6 feet tall and branched at the top. The leaves are alternate, deeply cut or lobed with five points per lobe, very spiny, 3 to 6 inches long and extend (clasp) down the stem. The waxy leaves are dark green with a light green midrib and mostly white margins. The large and showy flowers are terminal, flat, nodding, 1-1/2 to 2-1/2 inches broad, purple, rarely white, and surrounded by numerous, lance-shaped, spine-tipped bracts. Blooms appear in late May and June and set seed in June or JuIy. Seeds are straw-colored and oblong.

Musk thistle is commonly found in pastures, roadsides, and waste places. It prefers moist, bottom land soil, but can be found on drier uplands, also. It is becoming an increasing problem throughout Colorado, particularly along the Front Range.

Management Strategies | List of Troublesome Weeds | Back to Weed District