Canada Thistle - Cirsium arvense
Above: Canada Thistle on the shore of Lake Wingra in Wingra Park in Madison, Wisconsin. (7/11/19).
Canada Thistle - Cirsium arvense ( Introduced - naturalized; ecologically invasive and noxious weed)
Canada Thistle is a perennial, flowering plant that grows 1 - 4' tall.
Spines are on the edges of the leaves. No spines on stems and no prickly spines on the light pink flower heads that are about the size of the tip of your pinky finger.
Canada Thistle seeds are very fluffy.
Canada Thistle is highly aggressive. With its creeping roots, it can form large, dense colonies. Restricted Invasive - Eradicate!
Blooms: June-Oct.
Other names include: Creeping thistle, Field thistle (Not to be confused with Field Thistle (Cirsium discolor).
Above: Canada Thistle on the shore of Lake Wingra in Vilas Park in Madison, Wisconsin on August 26, 2022.
For more information on Canada Thistle, visit Wikipedia.
Or, visit the UW-Madison Wisconsin State Herbarium website page about Canada Thistle.
Or, to eradicate, visit the Wisconsin DNR website on Canada Thistle.
Canada Thistle
Cirsium arvense
Above: Canada Thistle on the shore of Lake Wingra in Vilas Park in Madison, Wisconsin on June 22, 2023.
Above: Canada Thistle on the shore of Lake Wingra in Wingra Park in Madison, Wisconsin on July 2, 2019.
Above: Canada Thistle in Oak Savana in Madison, Wisconsin on September 9, 2018.
Above: Canada Thistle on the shore of Lake Wingra in Wingra Park in Madison, Wisconsin on July 7, 2019.
Above: Canada Thistle on the shore of Lake Wingra in Wingra Park in Madison, Wisconsin on July 10, 2019.
Above: Canada Thistle on the shore of Marion Dunn Pond in Madison, Wisconsin on July 10, 2019.
Above: Canada Thistle on the shore of Lake Wingra in Wingra Park in Madison, Wisconsin on July 11, 2019.
Above: Canada Thistle on the shore of Lake Wingra in Vilas Park in Madison, Wisconsin on August 24, 2022.
Above: Canada Thistle on the shore of Lake Wingra in Vilas Park in Madison, Wisconsin on August 26, 2022.
Above: Canada Thistle specimen collected in Calumet County, Wisconsin on July 27, 1980.
Above: Canada Thistle specimen collected in Bayfield County, Wisconsin on Raspberry Island near Lighthouse on August 19, 1982.
Above: 1913 Canada Thistle (Cirsium arvense ) drawing.
Above: Canada Thistle (Cirsium arvense ) botanical illustration circa 1885.
Above: Canada Thistle (Cirsium arvense ) botanical illustration from the Atlas des plantes de France circa 1891.
Above: Video on Canada Thistle (Cirsium arvense ) identification by the University of Wisconsin Extension.
