Knapweed is of European origin. It is a biennial, or short-lived
perennial forb with a stout taproot. It can have one or more stems
that are branched , and from 1 to 3 feet tall. Basal leaves are
up to 6 inches long, and narrowly elliptic in shape, but can vary.
Flowering heads are solitary on top stem branches. Bracts around
the heads are stiff and tipped with a dark, comb-like fringe. This
is a key difference between spotted and diffuse knapweeds; the bracts
of diffuse are tipped with a definite slender spine. The showy flowers
of spotted knapweed are pinkish-purple, or rarely cream colored.
Spotted knapweed is often found on rangelands and other drier sites.