Squarrose Knapweed

Squarrose knapweed (Centaurea virgata Lam.)

Squarrose knapweedSquarroseknapweed, a member of the Sunflower family, is a long-lived tap rootedperennial reaching heights of twelve to eighteen inches. Stems arebranched, with deeply dissected lower leaves and bract-like upperleaves. Flowers are rose or pink colored, usually developing no morethan three to four seeds per head. Bract tips are recurved or spreading,with the terminal spine longer than lateral spines on each bract. Theseed heads are highly deciduous, falling off the stems soon after seedsmature.

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