Purple loosestrife

Prepared by Jennifer L. D’Appollonio, Assistant Scientist, University of Maine, Orono, ME 04469. Updated April 2019.

Scientific name: Lythrum salicaria L.

Common name(s): purple loosestrife

Links: USDA PLANTS Profile, Go Botany

Images: (to see enlargements [PC]: click on image, then right click and choose “view image”)



-considered an invasive species

-leaves are:

  • simple
  • opposite
  • whorled




-disturbed areas

-meadows and fields


-shores of rivers


-displaces native plants

-decreases plant and animal diversity

  • competition with purple loosestrife has been suggested as a contributing factor in the decline of the rare Long’s bulrush (Scirpus longii) in Massachusetts

– will hybridize with European wand loosestrife (Lythrum virgatum) and winged loosestrife (Lythrum alatum)

-grazed by white tailed deer, muskrat, and rabbits

-American coot, pied-billed grebe, black-crowned night heron, American goldfinch and gray catbird have all been observed nesting in purple loosestrife stands

-provides little to no food source for birds

-colonization can substantially reduce or eliminate open water in small marsh areas

– Important aquatic food plants for wildlife such as pondweeds (Potamogeton spp.) are inhibited under the shade of purple loosestrife

-Invading purple loosestrife in coastal British Columbia’s Fraser River estuary may have negative effects on detrital food chains


-eliminate small recent patches first with digging or hand pulling

-encourage establishment of native woody cover to create shade

-avoid disturbance

-high water conditions slow its growth

-cutting stems or removing flower heads

-beetles and weevils have been released to control purple loosestrife

-herbicides that have been used effectively against purple loosestrife in North America

  • 2, 4-D
    • Mixed results against purple loosestrife; harmful to dicots, but little impact on neighboring monocots
  • Triclopyr
    • Generally effective at killing purple loosestrife; results are variable with spray volume; selective against dicots
  • Glyphosate
    • Highly effective against purple loosestrife; specific formulations available for use in aquatic environments; also damages or kills most other plants which it contacts
  • Imazapyr
    • Effective against purple loosestrife; negatively impacts cattail

Natural History:

-native to Eurasia

-it was well established by the 1830s within coastal wetlands along the New England seaboard,

  • introduced via ship ballast soil.
  • Initial spread of purple loosestrife into the interior of eastern North America occurred primarily via routes of maritime commerce, such as canals, rivers and the Great Lakes



U.S. Forest Service. “Lythrum Salicaria.” Fire Effects Information System (FEIS), USDA, 2020, www.fs.fed.us/database/feis/plants/forb/lytsal/all.html.

Go Botany. “Lythrum Salicaria L.” Lythrum Salicaria (Purple Loosestrife): Go Botany, 2020, gobotany.nativeplanttrust.org/species/lythrum/salicaria/.