Centaurea repens L.
Russian knapweed is a perennial, grows from 1.5 to 3 feet tall and forms dense colonies. Black roots penetrate to over 8 feet deep. The flower is usually pink to lavender in color and forms on the end of a cone shaped head. The bracts on the flower are papery which differentiates it from the other knapweeds. Flowering occurs from seed and rhizomatous root system. This plant originated in Eurasia and was first reported in the United States in 1898. It now is widely established in the western United States.