Canada Thistle is a perennial that spreads by seed and creeping roots. Feathery hairs (papppus) attach to seeds to aid in short distance dispersal.
Perennial weeds grow from root stalks year after year. Perennial weeds spread by seeds and roots, and therefore the entire plant must be destroyed.
Classification: Noxious Weed
Stem: Upright, branching near the top, hollow
Leaves: alternate, slightly clasping the stem, variable, from a smooth margin with no spines to irregularly lobed with sharp spines
Flowers: Small white to purple flowers clustered into a head resembling a single flower, male (round) and female (flask or urn shaped) flowers found on separate plants, positioned at the ends of branches.
Contact your local office to learn more:
Calgary: Red Deer:
Tel: 403-206-9900 Tel: 403-358-3339
Information compliments of Agricultural Industry, AAA Fieldmen, Environment, Health & Safety Handbook.
For more information on Canada Thistle, check out this fact sheet issued by the Alberta Invasive Species Council at www.abinvasives.ca – Canada Thistle Fact Sheet.