Cirsium arvense (Canada Thistle) - Perennial

Size:

• Smallest of the target thistles; can grow up to 4 ft tall. Forms colonies.

Leaves:

• Oblong, spiny, bright green with shallow lobes and wavy margins; smooth above and slightly hairy underneath

Stem:

• Usually smooth, not winged or hairy; branches at top

Flowers:

• Small, teardrop shaped, mostly purple, can be pink or white; in clusters of 1-5 flowers at the end of branches. Male and female flowers are borne on different plants.

Blooms:

• June – August.

Roots:

• Deep aggressive creeping roots

Seeds:

• Brownish with a tuft of hairs at the top; dispersed by wind

Habitat:

• Pastures, ditch banks, riparian zones, meadows, cropland; grows best in moist areas

Control:

• Can reproduce from tiny root fragments as well as seeds, so hand-pulling is not effective. Mow repeatedly during the growing season. Difficult to control without herbicides.