Tyrol Knapweed (Centaurea nigrescens)

 
 
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Description
Perennial with a taproot. Stems are erect, branched, hairless or somewhat sparsely long-hairy, reaches 0.4-1.0 m tall. Basal leaves oblanceolate to elliptic, base tapering into the stalk, deeply to shallowly lobed or irregularly pinnately cut, hairless or often lightly hairy below, up to 15 cm long and 3 cm wide; stem leaves lanceolate, unstalked, reduced upwards. Flowers heads discoid, numerous, solitary at the ends of ascending branches; disk flowers reddish-purple, the marginal ones, if present, enlarged, lobed and conspicuous; involucres 12-15 mm tall, 8-11 mm wide; involucral bracts cylindric, taller than wide, with slightly enlarged, rounded, tattered to comb-like, darker appendages at the tips, these wider than the bracts.

Key Identifiers
  • Lobed leaves, terminal lobe much larger than other lobes, upper leaves are smaller, with few lobes
  • Bract tipped with triangular fringe, which ends abruptly, not tapering down the side of long slender green base of the bract
  • Flower color rose to purple
Location in Canada
BC, Ontario and Quebec have reported the presence of Tyrol Knapweed in Canada.

Resources
Pacific Northwest Extension Publication - Identification of Knapweed and Starthistles in the Pacific Northwest

Joseph M. DiTomaso, University of California - Davis, Bugwood.org

Eric Coombs, Oregon Department of Agriculture, Bugwood.org

Similar species
(Centaurea spp.) Other knapweeds are going to be similar to squarrose 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, leaves and stems of squarrose knapweed lack spines.
 
 
 
 

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Tyrol Knapweed (Centaurea nigrescens) - Current Document
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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 28, 2014.