Brown knapweed, Centaurea jacea L. [CENJA, centaurée jacée, Common knapweed, Star-thistle, jacée des prés] Perennial, reproducing only by seed. Similar to Spotted knapweed in habit and general appearance, but differing from it by having a coarser, more robust appearance, simple, undivided, but irregularly toothed, somewhat rough-hairy leaves, and by having the involucral bracts surrounding the flower head light brown, with the upper half of each bract expanded or flared out and torn into irregular divisions rather than fringed like the teeth of a comb, flowers from June to September.

Brown knapweed occurs chiefly in the western half of southern Ontario where it is sometimes very common in pastures, roadsides and waste places.