- Arctium minus
Common burdock (Arctium minus) is a tall, invasive biennial herb known for clinging burs that were not only the inspiration for Velcro, but also for lowering the health and market value of livestock. The burs get tangled in manes and tails of horses, cows and other livestock, and can also damage or de-value the wool of sheep. The large leaves of common burdock can shade out smaller plants. There have even been occasional incidences where birds and bats have become entangled in the burrs and perished. Heavily burred cattle become stressed, and experience eye, nose and mouth injuries that reduce their market value.
Considered regionally noxious under the BC Weed Control Act, common burdock is found in the Bulkley-Nechako, Cariboo, Columbia-Shuswap, Fraser-Fort George, Kitimat-Stikine, North Okanagan, Okanagan-Similkameen, Peace River, and Thompson-Nicola regions.
Plants grow up to 2 m tall, and are identified by erect, course stems that are branched and have a reddish tinge. Mature leaves are large, heart-shaped, and very hairy underneath, with lower leaves that grow up to 50 cm long. Leaf edges are wavy or toothed. Pink to purple flowers form clusters along the stems and bloom between July and October. Spiny, hooked modified leaves surround the florets, and clinging burs (fruit) are round, bristly and grow 10-22 mm wide.
Common burdock was introduced in the 1700s for its medicinal characteristics. It was also used to make paper and coffee.
Since common burdock plants can live up to four years, producing 6,000-16,000 seeds per plant, preventing the production of the burred seed is a key way to prevent spread. Mowing or cutting is best done before flowering to eliminate seed production. In order to remove this problematic plant fully, the large taproot system that grows deep underground must be tilled. Re-seed bare soil where possible, and encourage desirable, competing vegetation. Most broadleaf herbicides are also useful for control.