A bushy, branched perennial, Russian knapweed grows one to three feet tall and forms clones or colonies from its vigorous, spreading root system. The erect, hairy stems branch from above the middle or not at all. While young plants may have whitish and woolly stems, older plants will turn dark brown to black. The basal leaves are deeply notched and gray-green in color, while the upper leaves are smaller and linear with broken edges. The stem leaves are intermediate in size with toothed edges. The pink to purple flowers grow in solitary heads at the tips of leafy branches. The bracts under the flower heads are greenish to straw colored, with a broad, papery tip. Russian knapweed flowers from June to September, producing ivory-white seeds with a feather-like plume.

Habitat:  Russian knapweed is common on the heavier, often saline soils of bottomlands, as well as subirrigated slopes and flats. The species is also competitive in hayfields, pastures, grain fields, and along roads or irrigation ditches. In eastern Washington, Russian knapweed is commonly found on sites occupied by basin wildrye (Elymus cinereus).

Growth and Development: The species is a long-lived, persistent, perennial weed

Reproduction:  The plant reproduces by seed, although the seeds are too heavy to be wind-borne. Long-distance transport is typically as a contaminant in hay or seed lots. Plants can spread locally via lateral extension of the roots.

History:  Russian knapweed was originally introduced to the United States through alfalfa seed brought in from Turkestan near the turn of the century. Once imported, it was spread via domestically produced alfalfa containing Russian knapweed.

Russian knapweed is an aggressive and invasive noxious weed of pastures, non-crop areas, grain fields, and other cultivated fields. Livestock may avoid this species; in addition, the plant is poisonous to horses, causing chewing disease (nigropallidal encephalomalacia).