Cirsium arvense, July 28, 2020
Common & scientific name
Canada thistle, Cirsium arvense
Family
Sunflower, Asteraceae
Location
Roadside, 9,500’
Fun, weird, helpful, or little known fact
Talk about a scourge! Canada thistle is an A-1 noxious weed that will grow anywhere, including sadly on Indy Pass where it’s wet. Canada thistle was accidentally introduced to North America in the 1600s, and has since been designated a noxious weed in almost every state in the country. It can form dense stands that shade out and displace our beautiful native plants, changing the plant community structure and species composition and reducing biodiversity. It spreads rapidly and is extremely difficult to remove.
I wish I could tell you to pull it when you see it, but pulling makes it come back twice as hardy. Gah!!!