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Weed Identification

Virginia Tech College of Agriculture and Life Science Virginia Cooperative Extension

common burdock

Family

Asteraceae

Scientific Name

Arctium minus
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Other Common Names:

burweed
wild rhubarb
cuckoo-button
button-bur
lesser burdock

Synonyms (former Scientific Names):

Lappa minor

Habit

This biennial plant begins as a rosette of large leaves, and then progresses into a branching, erect plant with burs during its second year. It can flower as soon as June, and last through October in some cases.

Leaves

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. Plants produce a rosette of large leaves in the first year. For the second year, it develops a branched stem which has leaves arranged in an alternate fashion. Stems are erect, branched, hollow, hairy, and ridged. Stems may reach 5 ft in height.

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 that stick to clothing like common burdock.

Flower Seed Head

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). The 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.

Seed Fruit

The seeds develop in an achene, mottled dark-gray to black, 4-7 mm long, with a pappus of short bristles. The hooks on the achenes will often catch on clothing and animal fur to aid in seed dispersal. The individual seeds are brown to dark gray, rough, and usually 4 to 5 mm in length.

Where Found

Being biennial, this plant prefers undisturbed soils such as along fence rows, open farmland, waste places, roadsides, and undisturbed woods. Common Burdock can be found across the upper half of the United States.

Growth Habit

upright and nonwoody

Thorns or Spines

not present

Approximate Flower Diameter

Varies: 
dime, 
nickle, 
quarter

Dominant Flower Color

Varies: 
purple, 
pink

Flower Symmetry

not symmetrical

Leaf Hairs

has hairs

Leaf Shape

oval

Leaf Arrangement

alternate

Leaf Margin

Varies: 
entire, 
serrated

Leaf Structure

simple

Leaf Stalk

shorter than leaf

Stem Hairs

Varies: 
has hairs, 
no hairs

Stem Cross Section

round or oval

Milky Sap

not present

Root Structure

taproot

Life Cycle

biennial

Ochrea

not present

Plant Type

Herb