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Ministry of Agriculture, Food and Rural Affairs

cocklebur

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).

Seedlings

Stems

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

Leaves

  • 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)

Flowers

  • 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:
The seed is a frequent contaminant in small grains. 

Cocklebur seedling Cocklebur Cocklebur Cocklebur Cocklebur stem
Click to enlarge.