Purple Loosestrife (Lythrum salicaria)
Purple loosestrife (Lythrum salicaria)

Purple loosestrife

(Lythrum salicaria)


  • Introduced from Europe and Asia to the Atlantic coast of North America in the early 1800’s.
  • Up to 2 meters tall with several stalks covered in pinkish-purple spike-like flowers.
  • Flowers bloom from late June through to September.
  • Square 4-sided stem, lance shaped leaves that are arranged opposite from each other.
  • Produces 900 to over 2.5 million seeds per plant (dependant on age, vigor and size of plant).
  • May spread via plant parts, especially the roots.

Consequences of invasion

  • Forms dense stands with thick mats of roots, which degrades wetland habitats.
  • Decreases biodiversity.
  • Large infestations can clog irrigation canals, degrade farm lands and reduce forage values of adjacent pastures.

‘h2″Management Options

  • Best time to remove Purple Loosestrife is June, July and early August, when it is in flower and before seed set.
  • Dispose of Purple Loosestrife by bagging and disposing at your local landfill.
  • Biocontrol agents are available for this plant.

More information available:

Invasive Species Council of BC Factsheet
CKISS Downloadable PDF: CKISS Detailed Profile
ISCMV Purple Loosestrife Best Management Practices
Ontario’s Invading Species Awareness Program
Purple Loosestrife Manitoba: Manitoba Purple Loosestrife Project

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