(Centaurea virgata lam. var. squarrosa)
Not Known To Occur In Colorado
Squarrose knapweed is a tap-rooted long-lived perennial that reaches 1 to 3 feet in height. It has bract tips that are recurved or spreading with terminal spine longer than lateral spines. Flowers are borne in singles or pairs at the tip of each branch. The flowers are rose to pink colored and usually, the plant only produces 3 to 4 seeds per head. The flower heads appear more slender than other species of knapweeds. Deciduous seed heads fall off the stems after seeds mature. Seeds are bur-like and are dispersed by animal movement. Stems are branched with deeply dissected lower leaves and bract-like upper leaves.