Spotted Knapweed

Spotted knapweed

 (Centaurea stoebe)
*Established in Michigan*

Report this species:

Use the Midwest Invasive Species Information Network (MISIN) online reporting tool - http://www.misin.msu.edu/report/

- Or - download the MISIN smartphone app and report from your phone - http://www.misin.msu.edu/tools/apps/#home

 

A spotted knapweed plant grows in gravel near a fence post.

Michael Shephard, USDA Forest Service, Bugwood.org 

Pinkish-purple spotted knapweed flowers.

Rob Routledge, Sault College, Bugwood.org

A spotted knapweed rosette growing close to the ground.

Rob Routledge, Sault College, Bugwood.org

Identification:

  • An herbaceous, bushy, perennial plant growing 2-3 feet
  • Elongated, bluish- or grayish-green leaves divided into lance-shaped lobes. 
  • Pinkish-purple flowers are thistle-like and bloom from July through September
  • Long, stout tap-root can send shoots to start new plants
  • Seeds are carried on fine, white tufts emerging from the flower base.

Habitat: Often found in open fields or scrub-shrub areas with poor soils or sands and also in disturbed areas, hay fields and pastures

Native Range: Eurasia

U. S. Distribution:  Throughout most of the U.S. and Canada

Local Concern: Spotted knapweed is poisonous to other plants, creating barren areas where only knapweed grows.  It is a threat to pastures and dry ecosystems including prairies and dunes.  Can be a skin irritant.

MORE INFORMATION:

Spotted Knapweed Invasive Species Alert - Printable PDF