Volunteers and Invasive Plants: Learning and Lending a Hand link

U.S. Fish & Wildlife Service
America's National Wildlife Refuge System

Volunteers and Invasive Plants: Learning and Lending a Hand

Print  Click here to print this page  | Text Size: A A A
V&IP Home | Contact Us 

Back to Module

Canada Thistle Origin

Native to southeast Europe and Asia, Canada thistle is believed to have been introduced to the United States by the 1700s as a contaminant of crop seed.

Photo of numerous small flower heads of Canada thistle.

Numerous small flower heads
of Canada thistle

Photo of infestation of Canada thistle with purple and white flower heads.

Infestation of Canada thistle with purple and white flower heads

Photo credit: MT Dept. of Agriculture (left)
S Dewey/Utah State Univ., www.forestryimages.org (right)


Reference

Whitson TD, ed. 2000. Weeds of the West. Jackson (WY): Western Society of Weed Science. 628 p.