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Last Updated: Spring 2012

Synonyms: NONE

Family: Lythraceae

Home Range/U.S. Introduction:
Lythrum salicaria L. is native to Eurasia and is now naturalized over large areas of the United States. It apparently was introduced into coastal areas of the northeastern United States in the early 1800's (Stuckey 1980). Due to its attractive flowers, it has been planted as an ornamental garden species and has escaped from cultivation; it is now in at least 40 states and Canada.

U.S. Range Map:

Distribution was determined by a combining of the distribution information obtained from the following websites:

USDA, NRCS. 2012. The PLANTS Database (http://plants.usda.gov, 18 June 2012). National Plant Data Team, Greensboro, NC 27401-4901 USA.

U.S. Geological Survey. [2012]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/18/2012].

Species Description:
Plants are erect, emersed, much-branched perennials, glabrous to often pubescent, growing to 2 m tall. The stems are 4-angled. The leaves are opposite or whorled, sessile, mostly longer than the internode above, 2 to 10 cm long, 0.5 to 1.5 cm wide, the base obtuse to cordate. Flowers are whorled in showy terminal bracteate spike-like inflorescences. The 6 petals are rose-purple, up to 10 mm long. There are usually 12 stamens.

Habitat/Growth Characteristics:
Purple loosestrife grows in marshes, along pond, lake and river margins, canals, wet meadows, prairies and ditches. The plant regrows from a strong root stock, and a single plant can produce 2.5 million seeds annually (Malecki et al. 1993). In many wetland areas purple loosestrife produces large colonies.

Populations of purple loosestrife often spread so aggressively that native vegetation is suppressed and the structure and function of wetlands are altered (Thompson et al. 1987) and the value of wetlands for wildlife is reduced. Purple loosestrife may also degrade the quality of pasture and hay (Thompson et al. 1987) and impede the flow of water in irrigation canals (Malecki et al. 1993). It is estimated that 200,000 ha of wetlands in the United States are degraded annually through invasion of purple loosestrife.

Malecki, R. A., B. Blossey, S. D. Hight, D. Schroeder, L. T. Kok, and J. R. Coulson. 1993. Biological control of purple loosestrife. Bioscience 43(10):680-686.Stuckey, R. L. 1980. Distributional history of Lythrum salicaria (purple loosestrife) in North America. Bartonia 47:3-20.

Thompson, D. Q., R. L. Stuckey, and E. B. Thompson. 1987. Spread, impact, and control of purple loosestrife (Lythrum salicaria) in North American wetlands. U.S. Fish and Wildlife Research Report 2.