Found 2 items, similar to knapweed.
English → English (WordNet) Definition: knapweed knapweed n : any of various plants of the genus Centaurea having purple thistlelike flowers
English → English (gcide) Definition: Knapweed Knapweed \Knap"weed`\, n. (Bot.) The black centaury (Centaurea nigra); -- so called from the knoblike heads of flowers. Called also bullweed. [1913 Webster]