Invasive Species Council of British Columbia
Invasive Plant

Canada thistle

Cirsium arvense

About This Species

Canada thistle (Creeping thistle, California thistle, Cursed thistle) is a shiny green, spiny thistle native to Europe, Western Asia, and Northern Africa. It’s likely one of the first invasive species introduced to North America and received its name by early settlers blaming its emergence on French traders from Canada.  

Plants form thick infestations through creeping rhizomatous roots 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’s even considered an injurious weed species within its native range. Canada thistle is designated as a Provincial Noxious Weed by the BC Weed Control Act.  

How to Identify

Canada thistle is a shiny green, spiny plant that can grow from 0.3-2.0 m tall. It can be distinguished from other thistles by its smooth spine-less stem. 

Flowers are white to purple and grow in 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. Its flowers are typically smaller than other thistle species. 

Its leaves are a glossy green with sharp, spiny edges and has white hairs on the underside.  

Credit: E. Springinotic

Take Action

Prevention is the best approach.

Play Clean Go


Learn about best practices


Use the app

Observe and report to protect BC’s biodiversity

Report through this website

Use our form to tell us what you’re seeing and where.



Click or drag files to this area to upload. You can upload up to 3 files.
Please include photos of the suspected species to help potential identification by experts.
Please be specific and give us an address if possible.