Canada Thistle

Asteraceae

LIFE FORM: Perennial

NATIVITY: Eurasia

VEGETATIVE CHARACTERISTICS:

Erect, sparsely-branched stems grow to about 4 feet tall and produce alternate leaves with spiny margins.

FLOWERS:

Terminal clusters of pink-purple flowers in summer.

FRUIT/DISPERSAL AGENTS:

Wind dispersed seeds in fall; also spreads vigrously from root suckers.

ECOLOGICAL PREFERENCE:

Grows best in sites with deep soils. Prefers minimally maintained public parks and open space; vacant lots and rubble dump sites; abandoned grasslands (meadows); woodlands that develop on abandoned open space; railroad tracks with ballast substrate.

ENVIRONMENTAL FUNCTION:

Disturbance-adapted colonizer.

CULTURAL SIGNIFICANCE:

This long-lived perennial forms large colonies and can be difficult to eradicate; a tea made from the leaves is used as a tonic and diuretic.