Wildflowers of Toronto's High Park​​

Thistles

Family: Composite/Aster
Genus: Cirsium

​Introduced.  ​​

​Thistle, bull
​C. vulgare
 
Habitat: waste places
Blooms: June to September
​Biennial

​Height: Up to 1.5 m
Flower head: Up to 7 cm composed of disk florets.

​Stems and leaves very prickly.  Spiny yellow bracts beneath flower head.

Thistle, Canada
C. arvense

Habitat: Waste places
Blooms: June to October

Height: up to 150 cm
Flower head: 1-2 cm bearing only disk florets. 

Smooth stems but prickly leaves. 

Not native to Canada. The name is derived from the fact that it entered the US from Canada.