Common Burdock

Arctium minus

Weed Description
A biennial that produces a rosette of very large leaves in the first year and a branched stem with many burs during the second year. Found across the upper half of the United States and is most commonly found as a weed of pastures, hay fields, and fence rows.

Seedlings
Cotyledons are egg-shaped and widest near the apex (obovate) with a waxy surface. Young leaves are also egg-shaped, except at the truncated base.

Leaves
Rosette leaves are broadly heart-shaped, 6-18 inches long, 4-14 inches wide, with hollow petioles and wavy and toothed margins. The undersides of these leaves are loosely hairy and light green. Stem leaves are much smaller, alternate, and egg-shaped.

Stems
Produced during the second year of growth. Stems are erect, branched, hollow, hairy, and ridged. Stems may reach 5 ft in height.

Flowers
Occur in clusters at the ends of branches (terminal racemes) or in clusters that arise from the region between the stem and leaves (axillary racemes). Flowers are purple to lavender, occasionally white, with outer bracts that are "hooked". Flowers dry to a bur, and the hooked bracts are often confused with a thistle.

Fruit
An achene, mottled dark-gray to black, 4-7 mm long, with a pappus of short bristles.

Roots
Large taproot.

Identifying Characteristics
Large basal rosette of leaves with hollow lower petioles, and flowers with hooked bracts. After senescence, the remaining burs on the stems of common burdock may resemble a thistle. However, the dried flowers of thistle plants do not have hooked bracts like common burdock.

Office of Programs

University of Missouri

Common Burdock

Arctium minus