Lesser burdock, bardane, beggar’s button
Common burdock is a biennial weed that reproduces by seed. Seedlings emerge in early spring. The first year's growth produces a large rosette of broadly triangular or oval, bluntly pointed leaves. They are coarsely veined, 6 to 18 inches long and up to 10 inches wide. The upper surface is smooth to sparsely hairy and dull, dark green. The lower surface is light green and has a woolly texture. The leaves are round lobed at the base, and the margins are wavy or occasionally coarsely toothed. The thick leaf stalks (petioles) are green or purple, grooved, and usually hollow, at least in the lower portion. The rosette leaves die back in winter, but the root crown remains alive to send up new leaves the following spring. The second year rosette has a bushier form, and its leaves are rarely longer than 9 inches. A branched flower stalk emerges from the center of the rosette. Usually fully extended by late June, the stalk grows 2 to 5 feet tall and bears alternate leaves similar to those of the rosette, but about half the size. The burs that form on this stalk are actually composite flowers that bloom in late spring to midsummer. Many flower heads cluster in the leaf axils of the long central stalk. Heads are nearly round, 3/8 to ¾ inch across, and are topped with a corolla of rose-purple, petal like flowers. Slender hooked bracts surround the corolla and become dry and stiff as the bur ripens. Seeds are spread when the hooked bracts stick to passing animals or people. Very little effort is needed to dislodge and carry away whole clumps of these ripe seed heads. Each bur produces thirty to forty seeds inside its spherical pod. One plant can produce as many as 15,000 seeds with 90 percent viability. Seeds last one to three years in soil and require a cold period to germinate.
Common burdock leaves are wooly underneath and are very large. The prickly heads of the burs are noted for early catching on to fur and clothing. The leaves in the rosette stage are large and are usually heart-shaped.
Common burdock can be found along the foothills and brushy draws in the plains, right-of-ways, ditch banks, pastures and waste places.
Herbicides that control Common burdock are Milestone, Tordon, Escort, Dicamba, and 2, 4-D. Hand pulling and digging is effective if done before the flower. For more information about the herbicides, read the label or contact the Weed and Pest office.
The roots of Common burdock are eaten as a vegetable in Japan. This plant contains lactones that may cause dermatitis in humans and the burrs can reduce the value of wool. In folk medicine, tea was made from the roots to treat gout and rheumatism.