Scientific Name: Arctium tomentosum

Common Name: woolly burdock

Habit: These robust plants grow to 3 m in height and are umbrella-shaped with flower heads at the tips of the branches. It produces a large fleshy tap root during the first year of life. Stems are red and green striped.

Leaves: The first year of growth is a basal rosette. The leaves of the rosette are usually 45 cm long by 40 cm wide and are white and woolly beneath. The mature plants leaves are alternate and smaller in size toward the top of the plant. Leaves are ovate with a heart-shaped base.

Identifying Characteristics: Floral bracts are covered with soft hairs that spread at maturity (florets have sticky hairs). The hooked bristles on the floral bracts aid in the dispersal of seeds.

Flower Seed Head: Flowers can be found at the ends of branches in rounded or flat toped clusters. The clusters, 3 - 4.5 cm across, consist of purple disk florets surrounded by overlapping hooked bracts (like velcro).

Seed Fruit: An achene containing a single seed is approximately 6mm long. The seed a mottled brown club-shape is 5-6.5 mm long with barbed yellow bristles. Plants are capable of producing 12,000 seeds that remain viable for up to 3 years.

Where Found: This plant is often found in fence lines, waste areas, and stream banks throughout Canada and the northern two-thirds of the United States.

  • Life cycle: biennial

  • Milky sap: Not Present

  • Plant type: Herb

  • Thorns: Not Present

  • Plant family: Asteraceae

  • Leaf arrangement: alternate

  • Leaf shape: oval

  • Ochrea: Not Present

  • Leaf margin: serrated

  • Stem hairs: has hairs

  • Flower color: purple; pink; white

  • Growth habit: upright and nonwoody

  • Stem: round or oval

  • Leaf structure: simple

  • Leaf hairs: has hairs

  • Flower symmetry: radial symetery

  • Flower diameter: quarter; half dollar; nickle

  • Root structure: taproot

  • Leaf stalk: shorter than leaf