Great Burdock (Arctium lappa)

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Greater Burdock is rather tall biennial, reaching as much as 3 m. The fleshy tap-root can grow up to 1m long. It has large (up to 80 cm) alternating, heart shaped leaves that have a long petiole, very wavy margins and are pubescent on the underside. Basal leaf stems are solid. The flowers are purple and grouped in globular flower head, united in clusters. The flower head is surrounded by a whorls of bracts, each curving to form a Velcro like hook, allowing them to be carried long distances on the fur of animals.

Key Identifiers
  • Large plant and leaves
  • Lower leaf stalks are solid
  • Whorl of bracts 2.5–4.5 cm in diameter
  • Long stalked flowers
  • Flowers clumped along stem with branches in groups
  • Velcro like hooks on bracts
Location in Canada
Great Burdock occurs in all Canadian Provinces from New Brunswick to British Columbia. Sometimes grown for medicinal purposes.


Similar species
Lesser Burdock (Arctium minus) lower leaf stalks are hollow and flower heads are less than 2.5 cm across.

Wooly Burdock (Arctium tomentosum) flower heads are less than 2.5 cm across, densely cobwebby and flowers clumped along stem with branches in groups.

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For more information about the content of this document, contact Chris Neeser.
This document is maintained by Shelley Barkley.
This information published to the web on March 23, 2012.
Last Reviewed/Revised on August 21, 2018.