Tyrol Knapweed (Centaurea nigrescens)

Download 200K pdf file ("tyrol_knapweed.pdf")PDF
     Subscribe to our free E-Newsletter, "Agri-News" (formerly RTW This Week)Agri-News
This Week
  Return to the Weed Information Home Page
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.

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.

Other Documents in the Series

  Bighead Knapweed (Centaurea macrocephala)
Black Knapweed (Centaurea nigra)
Brown Knapweed (Centaurea jacea)
Common Crupina (Crupina vulgaris)
Common St John's-wort (Hypericum perfoatum)
Diffuse Knapweed (Centaurea diffusa)
Dyer's Woad (Isatis tinctoria)
Garlic Mustard (Alliaria petiolata)
Giant Hogweed (Heracleum mantegazzianum)
Giant Knotweed (Fallopia sachalinensis)
Hoary Alyssum (Berteroa incana)
Hybrid Japanese Knotweed (Fallopia x bohemica)
Hybrid Knapweed (Centaurea x psammogena)
Japanese Knotweed (Fallopia japonica)
Marsh Thistle (Cirsium palustre)
Meadow Hawkweed (Hieracium caespitosum)
Meadow Knapweed (Centaurea x moncktonii)
Mouse-ear Hawkweed (Hieracium pilosella)
Nodding Thistle (Carduus nutans)
Plumeless Thistle (Carduus acanthoides)
Puncturevine (Tribulus terrestris)
Red Bartsia (Odontites vernus)
Rush Skeletonweed (Chondrilla juncea)
Russian Knapweed (Rhaponticum repens)
Saltlover (Halogeton glomeratus)
Spotted Knapweed (Centaurea stobe ssp. micranthos)
Squarrose Knapweed (Centaurea virgata ssp. squarrosa)
Sulphur Cinquefoil (Potentilla recta)
Tansy Ragwort (Jacobaea vulgaris/Senecio jacobaea)
Tyrol Knapweed (Centaurea nigrescens) - Current Document
Yellow Starthistle (Centaurea solstitialis)
Share via AddThis.com
For more information about the content of this document, contact Chris Neeser.
This document is maintained by Shelley Barkley.
This information published to the web on April 2, 2012.
Last Reviewed/Revised on August 21, 2018.