The biology of Canadian weeds. 6. Centaurea diffusa and C. maculosa.
A summary of biological information on C. diffusa (diffuse knapweed) and C. maculosa (spotted knapweed) is presented. The knapweeds are common on semi-arid rangeland, highway and railroad right-of-ways and waste places in southern British Columbia. Spotted knapweed is also common in eastern Canada. From summary.