Cirsium arvense

Click on the images below to see larger versions. 

Scientific Name Cirsium arvense USDA PLANTS Symbol CIAR4
Common Name Canada Thistle ITIS Taxonomic Serial No. 36335
Family Asteraceae (Sunflower) SEINet
Reference
Click Here
Description Life zones and habitat: Plains to montane. Disturbed areas, pastures, roadsides, croplands.
Plant: Erect perennial, 1 to 4 feet tall; stems are grooved and branched near the top.
Leaves: Oblong to elliptic, 1 to 12 inches long, with edges entire, shallow or deeply-pinnately-lobed with spines.
Inflorescence: Lavender composite flower heads about 1-inch across; green to purplish bracts. Male and female flowers on separate plants.
Bloom Period: June to October.
References: "Wildflowers of the Rocky Mountains" by Carl Schreier and SEINet.
BONAP Distribution Map

Colorado Status:
Noxious Weed



© Tom Lebsack 2021