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Back to Invasive Plants

Spotted Knapweed

spotted knapweed

Common name: Spotted Knapweed

Scientific name: Centaurea biebersteinii

Family: Asteraceae

Description

Knapweeds resemble thistles but lack spiny leaves. 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. Alaska has an active program of eradication.

Range in Yukon

It has been reported near Watson Lake and was removed from Haines Junction after several years of effort.

Similar Species

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

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 when it displaces grass there is less for them to eat.

Control

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.

 

 

Contact Environment Yukon

Government of Yukon

Box 2703 (V-5N)
Whitehorse, Yukon
Canada Y1A 2C6

Bruce Bennett, Wildlife Viewing Biologist

Phone: 867-667-5331
Toll free (in Yukon): 1-800-661-0408 local 5331
Fax: 867-393-6263

Email: bruce.bennett@gov.yk.ca

Last Updated: May 11, 2010 | © 2011 Government of Yukon | Copyright | Privacy Statement | Disclaimer