Common Burdock Arctium minus

Common Burdock is a weedy, biennial, herbaceous wildflower belonging to the Aster family. Native to Europe, it is now widely distributed in many parts of the world. Accidentally introduced to the U.S., it is tenacious and aggressively invades disturbed areas, empty lots, parks, roadsides, prairies, fields and pastures. This plant is on the Federal USDA list of Introduced, Invasive and Noxious Plants and is found across most of North America. Some states list this plant as invasive, but North Carolina is not yet one of them. Once established, growth is difficult to eradicate due to deep tap roots and copious amounts of seed that disperse widely and remain viable for a long while even if plants are destroyed. A single plant can produce 15,000 seeds. Robust growth potentially competes with beneficial native species. The first year's growth forms a short, dense rosette of leaves. In its second year, it bolts to heights 3-6 feet, develops very large heart-shaped leaves, pink to purple thistle-like flowers on branched stems, and slender tap roots growing to depths of one foot. Clusters of purple flowerheads are arranged on short stalks on the upper ends of stems. Flowerheads consist of many disk florets and globular bracts terminating in fine, sharp hooks forming prickly burs that aid in seed dispersal by latching onto animals, birds, or hay bales. Burs are very difficult to remove and reportedly have killed small birds and bats that become entangled. Fruits (achenes) within these burs contain sharp, minute bristles (pappas hairs) that easily become windborne and, if exposed to them, can cause severe eye, skin, and respiratory irritation and/or infection in humans, dogs, horses or other livestock. In dairy animals, Common Burdock may taint milk if ingested in sufficient quantity. The pollen from the blooms is collected by bumblebees, honeybees, Miner bees and Leaf-cutting bees, who also feast on the nectar.  The foliage is a food source for the caterpillar of the Painted Lady butterfly. It prefers full sun locations with moist, well drained soil rich in organic matter and nitrogen. It may host root rot and powdery mildew, potentially impacting agricultural crops. In Asia and other parts of the world, Common Burdock has been cultivated for for its edible roots and stems and medicinal uses. Cultivated plants are sown from seed in summer and first-year roots are harvested by late autumn before becoming too fibrous.  After peeling away the outer husk of young stems, the pith can be eaten as a vegetable.

Insects, Diseases, and Other Plant Problems:  This plant is weedy, invasive and difficult to eradicate once established.   It is susceptible to powdery mildew and root rot with potential to impact agricultural plants.  Burs and bristles may cause severe eye, skin or respiratory problems in humans, dogs, horses, and other livestock.  Burs are difficult to remove from animals and clothing.