BACKGROUND: Squarrose knapweed is a native plant of the eastern Mediterranean area. It is very competitive on rangelands. Knapweed releases chemical substance that reduces competing vegetation.

DESCRIPTION: This long-lived herbaceous weed has a simple taproot and grows 12 to 18 inches tall. The rosette and stems have deeply-lobed leaves. Flowers are rose to pink. It is often confused with diffuse knapweed, but differs in that the terminal spines on the flower bracts are curved outward and are not laterally toothed. Bloom occurs in the early to mid-summer.

CONTROL: Several biocontrol agents are available. Herbicides offer good to excellent control.