Garden Loosestrife

(Lysimachia vulgaris)

Description

  • Bright yellow, five-petaled flowers clustered at the top of the plant
  • Calyx has reddish-brown margins
    Coloured Calyx & Hairy Leaves. Credit: Catholic University of Leuven, Belgium.
  • Leaves: lance-shaped, dotted with black or orange glands, arranged oppositely or in whorls around the stem
  • Stems & leaves are softly hairy
  • Grows in moist habitats, such as wetlands, riparian areas, and lakeshores, but it can also grow in upland sites
  • Spreads by seeds & rhizomes (rhizomes can be up to 15 feet long!)
  • Native to Eurasia, and introduced as a garden ornamental

Consequences of Invasion

  • Garden loosestrife’s dense & aggressive growth habit damages shoreline & wetland ecosystems by replacing beneficial native plants
  • Reduces habitat needed by waterfowl, wildlife, birds, and fish, including salmon
  • Impedes water-recreation opportunities
  • This plant is so aggressive that it has been known even to outcompete Purple Loosestrife, which itself is so invasive that it can replace 50 – 100% of the native biomass in wetlands! (Thompson et al. 1987)
    Shoreline Invaded by Garden Loosestrife. Credit: KIng County website.

Integrated Pest Management Options

  • Prevention! Be PlantWise! Grow non-invasive or native plants in your garden
  • Mechanical: Small areas of seedlings can be dug up & larger isolated plants can be removed by hand if care is taken to remove all rhizomes
  • Cultural: Covering seedlings or very small populations with black plastic may be effective
  • Biological: No bio-control agents are known, and no research to discover these agents is currently being conducted

Garden loosestrife looks very similar to yellow loosestrife (Lysimachia punctata), but the flowers of the yellow loosestrife grow all along the stem, not clustered at the top, and they are star-like.

Garden Loosestrife Flower Cluster. Credit: Catholic University of Leuven, Belgium.
Yellow Loosestrife Flowers Along Stem/Lysimachia punctata. Credit: Bjoertvedt.