Common Burdock (Arctium spp.)
Common burdock is a large, leafy biennial that produces prickly burs. The leaves grow up to 50cm long and 30cm wide, are dark green above and hairy below. Purple flowers form in clusters along the stem; bloom period is July to September. Seeds are contained in a bur that easily clings to wildlife and clothing.
LRISS Category: STRATEGIC CONTROL
Habitat and Ecology
Grows in low- to mid-elevations in grasslands, forests, and riparian areas. It is often seen in ditches, roadsides, and stream banks. It prefers moist environments with nutrient-rich soils. It is not tolerant of cultivation or severely disturbed sites.
Common burdock sticks to the fur, hair, and wool of livestock. It can reduce the value of wool in sheep. Livestock like to eat burdock, but if eaten in large quantities it can cause bitterness in milk. It is a diuretic and is listed as poisonous to humans.
Cultivation will kill plants at the rosette stage (first year of growth). Mowing or cutting stems after bolting but before seeding will eliminate seed spread. New infestations can be prevented by maintaining healthy native communities, minimizing disturbance, and eliminating seed spread. Herbicides including 2,4-D, picloram, dicamba, and glyphosate are effective on first-year rosettes. Before application refer to the BC Ministry of Agriculture, Food and Fisheries Crop Production Guides.
Province of British Columbia. 2002. Guide to Weeds in British Columbia.
Photo Reference: Mary Ellen (Mel) Harte, Bugwood.org