Invasive Plant

Canada thistle

Cirsium arvense

About This Species

Canada thistle, despite its common name, is native to Europe and N. Asia. It spreads by its creeping roots. Plants form thick infestations that crowd out forage grasses in pastures and rangelands, reducing crop yields and production. Canada thistle is commonly found growing on roadsides, cultivated fields, pastures, logged forests, riverbanks, and other disturbed areas where it also out-grows native species. It is considered a noxious weed throughout the province.

How to Identify

It grows 0.3 to 2.0 m tall, has shiny green leaves with sharp, spiny edges and has white hairs on the leaf’s underside. It has clusters of up to five pompom-like flowers on stem tips with a faint vanilla scent. Seeds look like a dandelion i.e., parachute-type seeds. You can tell Canada thistle from all similar species by its smooth main stem and small flowers.


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