Squarrose Knapweed

Centaurea virgata Lam.

Squarrose Knapweed

Squarrose knapweed, a member of the Sunflower family, is a long-lived tap rooted perennial reaching heights of twelve to eighteen inches. Stems are branched, with deeply dissected lower leaves and bract-like upper leaves. Flowers are rose or pink colored, usually developing no more than three to four seeds per head. Bract tips are recurved or spreading, with the terminal spine longer than lateral spines on each bract. The seed heads are highly deciduous, falling off the stems soon after seeds mature.

Squarrose knapweed is a competitive rangeland weed native to the eastern Mediterranean area. It is not yet widely distributed in the West, but has gained footholds in Utah, California and Oregon. It has also been located in western Colorado.