Spotted Knapweed

Centaurea stoebe

Description 4

Knapweeds resemble thistles but lack spiny leaves and stems. They are biennial or short-lived perennials. This species reproduces entirely by seed. Large plants can produce over 20,000 seeds. It has not been known to be a problem in Yukon, but to date it has not had a chance to get established here. British Columbia and Alaska have active programs of eradication. Spotted Knapweed is a restricted noxious weed in BC.

Range in Yukon 4

Spotted Knapweed has been reported from the Alaska Highway near Hays Creek, the Carcross Desert.

Similar Species 4

Corn Flower (Centaurea cyanus) is an annual garden plant that is sometimes found in commercial “wildflower” mixes. It is occasionally found on roadsides but is not known to persist.

Ecological Impact 4

Knapweeds may invade undisturbed grasslands and produce chemicals that hinder growth and germination of other plants, reducing biodiversity and changing community structure. Also, grazing animals dislike the bitter taste of knapweed so it reduces the productivity of forage lands.

Control 4

The seeds of thistle and knapweed continue to mature after pulling. You may put plants into clear garbage bags and then leave them in the sun to kill off the plants and roast the seeds.

For more information visit: Yukon Invasive Species Council

Sources and Credits

  1. (c) Matt Lavin, some rights reserved (CC BY-SA), http://www.flickr.com/photos/35478170@N08/3768272782
  2. (c) Kristian Peters, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/26213090@N05/2478819390
  3. (c) Matt Lavin, some rights reserved (CC BY-SA), https://www.flickr.com/photos/plant_diversity/8047578011/
  4. (c) L.G. Johanson, some rights reserved (CC BY-SA)

More Info

iNaturalist.ca Map

Plant Daisy Family (Asteraceae)
Color pink