Eastern Forest Threat Center - Purple Loosestrife

Search Again

State Information

Select a state,
then click a link.

  • State Forest Agency
  • State Cooperative Extension

County/Parish Information

Select a county,
then click a link.


Purple loosestrife plants

Purple loosestrife plants

David Cappaert, Michigan State University, Bugwood.org

Purple Loosestrife
Lythrum salicaria

Purple loosestrife is native to Great Britain, central and southern Europe, central Russia, Japan, Manchuria China, southeast Asia, and northern India.

Keywords: Lythraceae, perennial, herb, 4-sided stems, downy pubescence, magenta flowers, seed capsules, fibrous rhizomes, dense mat, wetland, homogeneous stands

Distribution Map Distribution Source Image

Threat Description

Purple loosestrife is an erect perennial herb growing to a height of 3-10 ft. Mature plants can have 1 to 50 4-sided stems that are green to purple and often branching, making the plant bushy and woody in appearance. Leaves are opposite or whorled and lance-shaped. Plants are usually covered by a downy pubescence. Magenta colored flowers with 5 to 7 petals bloom from June to September. Seeds are borne in capsules that burst at maturity; single stems can produce an estimated 2 to 3 million seeds per year from one rootstock. The root system consists of a large, woody taproot with fibrous rhizomes which spread rapidly to form dense mats that aid in plant production. Purple loosestrife can invade wetlands such as freshwater wet meadows, tidal and non-tidal marshes, river and stream banks, pond edges, reservoirs, and ditches. As it establishes and expands, it can out compete and replace native grasses, sedges, and other flowering plants that provide a higher quality source of nutrition for wildlife. It forms dense, homogeneous stands that reduce habitat for waterfowl and restrict native wetland plant species, including some federally endangered orchids.