Purple Loosestrife


  • Square stalks, five or six-sided, woody, with several stalks on mature plants
  • Downy, long, narrow leaves with pointed tips, smooth edges and heart-shaped bases
  • Showy 1-inch flowers; 6 purple-pink petals and yellow-white centers
  • Height 4 to 6 feet

Weed Pictures

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Weed Information

ControlCultivation, biological and aquatic herbicide. Contact your County Weed District or local Applicator for more information.
HabitatRiparian areas including sub-irrigated pastures, cropland, ditch banks, lakes and rivers.
RootExtensive root system.
Leaf ShapeLance-shaped with smooth edges.
LifespanPerennial; two years or longer.
Priority 1B WeedLimited presence in Montana.
Similar Looking PlantsBlazing star and fireweed.
Important InformationPlants emerge in very early spring and have bloomed and set seed by mid-summer. The plant was introduced as a medicinal herb and an ornamental. One mature plant can produce more than 2 million seeds annually.