Spotted Knapweed
Centaurea Biebersteinii



IDENTIFICATION

Provincial Noxious Biennial or short-lived perennial.
Spotted knapweed has hairy, deeply-cut leaves and purple (or occasionally white) flowers on one or more upright stems. Flowerhead bracts have a black-tipped fringe that gives a spotted appearance. Spotted knapweed grows to a height of 1.5 metres and has a stout taproot. Contact can cause skin irritation.

DAMAGE
Spotted knapweed is a highly competitive weed that reduces or displaces desirable forage in disturbed areas, and sometimes invades adjacent areas that are relatively undisturbed. It forms near monocultures in some areas of British Columbia.

HABITAT
This type of knapweed is widespread at low- to mid-elevation grasslands and dry open forests. It has adapted to well-drained soils and can survive in very dry climates such as those of Ashcroft and Osoyoos, but doesn't like dense shade. Spotted knapweed occurs frequently in southern British Columbia east of the Coast-Cascade Mountains and is present on Vancouver Island and the mainland. It is a major concern in the Kootenay, Okanagan, Thompson, Cariboo, Omineca, and Peace River regions.

SPREAD
This species is prolific, with individual plants producing up to 140,000 seeds per square metre. Although seeds are shed in the immediate area around the parent plant, they are often spread much more widely in hay and on vehicle undercarriages.

 


 
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