Russian Knapweed
Centaurea repens
Asteraceae
(Sunflower family)

Russian knapweed is a native of Eurasia, probably introduced in North America about 1898. It is now widely established in the Western U.S. and heavily infests some regions of Fremont County. The species forms colonies in cultivated fields, orchards, pastures and along roadsides.

Growth Habit: Upright perennial herb, up to 3 feet tall, often grows in dense clumps. Grayish color.

Leaves: Alternate, simple, of several types: Upper leaves are small, narrow, unbroken edges. Stem leaves are intermediate in size with slightly toothed margins. Basal leaves are deeply notched.

Stems: Numerous branches, each ending with a single flower.

Flowers: Single, terminal, white to lavender, cone-shaped, scaly seed head. Many pearly bracts form with rounded or acute papery margins. Flowering occurs from June to September and seed is produced in late summer to early fall.

Roots: Dark brown to black and heavily scaled. Taproot can grow 8 feet long or more, and a system of creeping horizontal roots produces many more plants.

Other: Russian knapweed might be referred to as a “steam roller” on the noxious list because it has the ability to completely overrun an area if not contained. Russian knapweed is poisonous to horses (affecting the liver) and is not grazed by other livestock if another choice exists.