Brown Knapweed (Centaurea jacea)

 
 
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Description
Perennial plant that can reach 30-150 cm tall. Basal leaves are up to 15 cm long, tapering at both ends with the broadest part above the middle of the leaf. Stem leaves are lance-shaped, shallowly-lobed and stalkless. Flowers are rose-purple in color, rarely white, up to 2.5 cm wide. Heads are solitary at the ends of the upper branches. The bracts of brown knapweed are light to dark brown, with a papery, translucent margin. Ridged stems and sometimes purple-striped.

Key Identifiers
  • Leaves entire or toothed, basal ones broadly elliptic and occasionally lobed
  • Bracts that are without comb-like fringe and that have a brown, papery, translucent tip.
  • Woody crown root
  • Well visited by nectar insects
  • Brown knapweed prefers moister, cooler conditions than the other knapweed species
Location in Canada
BC, NB, Ontario and Quebec are all know to have this knapweed. Alberta does have one isolated report from CFB Wainwright but population has been eradicated and is being monitored.

Cindy Roche, Bugwood.org

Cindy Roche, Bugwood.org
Resources
Pacific Northwest Extension Publication - Identification of Knapweed and Starthistles in the Pacific Northwest

Similar species
(Centaurea spp.)Other knapweeds are going to be similar to brown knapweed. The key feature for differentiating all knapweeds from one another is to compare the unique bracts. The link under “Resources” is an excellent resource to walk you through identifying knapweeds.

May be mistaken for a thistle at a passing glance but upon inspection, all parts of brown knapweed lack spines.
 
 
 
 

Other Documents in the Series

 
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Black Knapweed (Centaurea nigra)
Brown Knapweed (Centaurea jacea) - Current Document
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Rush Skeletonweed (Chondrilla juncea)
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Saltlover (Halogeton glomeratus)
Spotted Knapweed (Centaurea stobe ssp. micranthos)
Squarrose Knapweed (Centaurea virgata ssp. squarrosa)
Sulphur Cinquefoil (Potentilla recta)
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For more information about the content of this document, contact Nicole Kimmel.
This document is maintained by Shelley Barkley.
This information published to the web on April 2, 2012.
Last Reviewed/Revised on March 21, 2014.