Common Burdock

Arctium minus

Keys to Identification

Dried burs stay attached to standing dead plants

Family

Asteraceae – Sunflower family

Other Names

Lesser burdock, Bardane, Beggar’s buttons, Beggars lice, Wild Rhubarb, Thorny bur

USDA Code

ARM12

Legal Status

Colorado Noxious Weed List C

Identification

Lifecycle

Biennial

Growth form

Forb/herb

Flower

Flower-head with numerous pink to purple tube-shaped disk flowers. Modified bracts below have curved tips that act as hooks. Flower-heads remain attached to the plant once it has dried up. Flowers are about ¾-1 inch wide and grow at the leaf axils and ends of branches either in groups or singly. June-October

Seeds/Fruit

Seeds are oblong, brown, ¼ inch long, with a tufted bristle. The bristle falls off as the seeds age. Each plant can produce 15,000 to 400,000, seeds

Leaves

Rosette leaves are up to 20 inches long by 12 inches wide. Stem leaves are smaller than rosette leaves, heart shaped, dull green above with very hairy undersides

Stems

Many branches, rough, hairy, hollow, grooved lengthwise

Roots

Very large, thick, fleshy, brown taproot

Impacts

Agricultural

Taints milk, reduces forage, and reduces wool value. Alternate host for powdery mildew and root rot

Ecological

Displaces desirable plants. Invades pastures, hay fields, prairies, and other open areas

Human

Considered toxic due to diuretic effects. Possible allergic reactions

Habitat and Distribution

General requirements

Most common in pastures, roadsides, stream banks, abandoned farmsteads, and waste sites

Distribution

Reported in all the lower 48 states except Florida

Historical

Originated in Europe. Was so widespread in North America in 1663 it was thought to be native

Biology/Ecology

Life cycle