Scotch Thistle (Onopordum acanthium)

Scotch Thistle

(Onopordum acanthium)

Description

  • Native to Europe and Asia.
  • Biennial or perennial.
  • In the Sunflower family.
  • Tall, coarse, spiny thistle.
  • Can grow to 2 or more meters tall.
  • Branched stems with spin-margined wings.
  • Large purple flower heads.
  • Tolerates a variety of soils, prefers moist soils.
  • Very limited distribution, single sites in Nelson, Castlegar, Rossland and Slocan valley.

Consequences of invasion

  • May be competitive with native vegetation in rangelands.
  • Forms dense stands that are impenetrable to livestock.

Integrated Pest Management Options

  • Pull or dig small infestations when soil is moist.
  • Cut a few inches below the soil surface.
  • Mow or slash before seedset.
  • Chemical control may work on larger infestations.
  • Re-establish competitive perennial grasses and monitor yearly.

More information available: