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Malheur Experiment Station
Oregon State University

Cirsium arvense

Canada thistle (Cirsium arvense)
Cirsium arvense
Common Names Canada thistle
Family Composites, Sunflower
Flower Color Purple
Plant Type Herb
Short Description Perennial, deep-seated creeping underground roots. Leaves: Spiny, pinnatifid
Location McCall
Native No
Weed Noxious

Canada thistle (Cirsium arvense)
Canada thistle (Cirsium arvense)
Canada thistle (Cirsium arvense)
Canada thistle (Cirsium arvense)
Canada thistle (Cirsium arvense)

Canada thistle (Cirsium arvense)
Canada thistle (Cirsium arvense)
Canada thistle (Cirsium arvense)
Canada thistle (Cirsium arvense)
Seeds are starting to disperse.

Canada thistle (Cirsium arvense)
Canada thistle (Cirsium arvense)
Canada thistle, Cirsium arvense Canada thistle, Cirsium arvense

Canada thistle, Cirsium arvense
Canada thistle, Cirsium arvense
Canada thistle, Cirsium arvense

Canada thistle produces a lot of bristly-plumed seeds. These seed spread by the wind. Canada thistle is a noxious weed, partly because it has aggressive sprouting from its perennial root system.


For additional information please send an e-mail request to:
Dr. Clinton C. Shock
Clinton.Shock@oregonstate.edu

Malheur Agricultural Experiment Station
595 Onion Avenue
Ontario, OR 97914
(541) 889-2174
FAX (541) 889-7831

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