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”)

Description:

-perennial

-considered an invasive species

-leaves are:

  • simple
  • opposite
  • whorled

Habitats:

-sun

-wetlands

-disturbed areas

-meadows and fields

-marshes

-shores of rivers

Agriculture:

-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

Management:

-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

 

Sources:

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/.