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Diffuse and Spotted Knapweed

Diffuse Knapweed     Diffuse Knapweed
     Centaurea diffusa

  • grows 1-1/2 to 2 feet tall
  • flowers are mostly white and solitary
  • when plant is young, the leaves have a knap which becomes rough with age
  • has a sharper spine at the end of the bract (modified leaf just below the flower)
  • produces 400 to 900 seeds the second year and lives up to four years in the same location
  • control goal is to prevent the production of seed


Spotted Knapweed
Centaurea maculosa Spotted Knapweed

  • grows up to 4 feet tall
  • flowers are solitary pink to lavender heads at the top of the shoot
  • leaves are hairy, hence the knap
  • seed head bracts are black tipped
  • control goal is to prevent the plant from producing seed
  • plant continues to grow yearly unless treated
  • an aleopath, knapweed species produce a chemical herbicide that prevents the growth of surrounding plants