Russian knapweed is a herbaceous perennial in the sunflower family (Asteraceae). Originally from Eurasia, it was introduced to North America in the late 1800’s as a seed contaminant in alfalfa. This List B noxious weed is found in many disturbed areas such as pastures, grasslands, and roadsides. Russian knapweed has been found in most counties in Colorado.

The leaves are generally 1½ - 4 inches long, attached to erect and branched stems. It has pinkish to lavender colored flowers and blooms from June to August. The flower heads have tan, rounded bracts with papery tips. Russian knapweed reproduces by seed but more often by its creeping roots. The roots can grow horizontally to about 15 feet and vertically to about 22 feet. New plants can easily form from root fragments as small as an inch.