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Invasive Plants
- Perennial Sow Thistle
- Creeping Thistle
- Oxeye Daisy
- Common Tansy
- Spotted Knapweed
- Narrowleaf Hawksbeard
- Scentless Chamomile
- Leafy Spurge
- Foxtail Barley
- Altai Wild Rye
- Crested Wheat Grass
- Smooth Brome
- Quackgrass
- Reed Canary Grass
- Bird Vetch
- Lucerne
- Sweetclover
- Greater Butter-and-Eggs
- Dalmatica Toadflas
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) Bruce Bennett, Wildlife Viewing Biologist Phone: 867-667-5331 Email: bruce.bennett@gov.yk.ca |