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Ministry of Agriculture, Food and Rural Affairs


Scientific Name: Xanthium strumarium L.

Other Names: lampourde glouteron, Bur, Clotbur, glouteron

Family: Composite or Aster Family (Compositae

General Description: Annual, reproducing only by seed.

Habitat: Occurs throughout Ontario. Present in and around farmyards, in fields, along roadsides and river flats. Common in low areas. Common in fine-texture soils (clays, clay loams).



  • Erect, usually much-branched
  • 30- 120 cm (12- 48 in.) high
  • Rough-hairy often with lengthwise ridges and spotted


  • Stalked
  • Oval or triangular
  • Somewhat angular heart-shaped at the base
  • Edges of the lowermost main branching veins usually exposed in a broad V or M
  • Margins are coarsely toothed
  • Surfaces are harsh or rough-hairy
  • Lower leaves opposite (2 per node); upper leaves alternate (1 per node)


  • Flower heads clustered in axils of leaves and at ends of branches
  • Sexes in separate heads but both sexes on the same plant
  • Heads of male flowers small, spherical, not spiny
  • Heads of female flowers are larger, become very hard and woody, covered with slender, hooked spines and terminating in 2 hard, hooked, beak-like spines and turn brown at maturity
  • Flowers from August to October

Often Confused With
Giant Ragweed (Leaves of cocklebur are mostly alternate while the leaves of giant ragweed are opposite.)

Caution: Seedlings of Cocklebur are poisonous to livestock, especially to young pigs which seem to relish their taste.

Cocklebur seedling Cocklebur Cotyledon Cocklebur Cocklebur stem
Click to enlarge.