COMMON NAME

Purple loosestrife


FULL SCIENTIFIC NAME

Lythrum salicaria L.


FAMILY NAME COMMON

Loosestrife family


FAMILY SCIENTIFIC NAME

Lythrum salicaria


IMAGES


Habit

Inflorescence

Incursion

Inflorescence close-up

Habitat

Inflorescence Close-up

NOMENCLATURE/SYNONYMS

Synonyms: None


DESCRIPTION

Botanical Glossary

Lythrum salicaria is an herbaceous wetland perennial that can grow 0.5-1.5 m (1.5-5 ft.) tall. The leaves are either opposite or in whorls of three. The can be pubescent or glabrous. They are lanceolate to linear in shape and 3-10 cm (1-4 in.) long. The larger leaves can be cordate or clasping at their bases. The flowers are purple, magenta or pink. They are numerous and borne on spikes that are between 10 and 40 cm (4-16 in.) long. The hypanthium is linear and twice as long as the sepals. Each flower has 5-7 petals, and the open flowers measure 7-12 mm (0.3-0.5 in.) in diameter. The relative lengths of styles and stamen in these flowers can vary in three different ways. The flowers are in bloom from July to September. The fruits are capsules, each containing numerous reddish-brown seeds. Page References Bailey 719, Crow & Hellquist 203, Fernald 1048, Gleason & Cronquist 311, Holmgren 292, Magee & Ahles 758, Newcomb 351, Peterson & McKenny 224,288. See reference section below for full citations.


SIMILAR SPECIES

Lythrum alatum Pursch. (winged loosestrife)* Picture of L. alatum Lythrum alatum is a rare plant that could be confused for L. salicaria. Lythrum alatum is usually shorter in stature, being around 40-80 cm (1-2.5 ft.) tall. The leaves of L. alatum are alternately arranged, except for the very lowest ones on the plant. The flowers of L. alatum are solitary in the upper axils while the flowers of L. salicaria are numerous and in a spike-like arrangement.


REPRODUCTIVE/DISPERSAL MECHANISMS

Lythrum salicaria reproduces through prolific seed dispersal. The seeds usually fall to the ground after they have ripened. They can be moved longer distances by water or by becoming attached to waterfowl.


DISTRIBUTION

The native distribution of Lythrum salicaria is central and southern Europe, Great Britain, and parts of Russia. It has been reported from every state in the United States except for Florida, Arizona, Louisiana, Georgia, Alaska and Hawaii. This plant occurs widely in New England.


HISTORY OF INTRODUCTION IN NEW ENGLAND

The first report of Lythrum salicaria in North America was in 1814. Before the year 1900, 14 of 30 populations of this plant were located in estuaries from Massachusetts to New Jersey. The location of these sites would indicate that the plant was introduced somewhere in this area. There are several hypotheses on how this plant was originally introduced. It could have been a part of ship ballast from Europe, or attached to sheep. Lythrum salicaria was also planted as a source of nectar for beekeeping, as an ornamental, and for medicinal reasons. By the 1900's there were more inland populations being reported, one of these being in New Hampshire. Since these initial introductions it has spread by being planted in gardens and by waterways.


HABITATS IN NEW ENGLAND

Coastal Grassland, Herbaceous Wetland, Lake or Pond, River or Stream, Shrub Wetland, Wet Meadow, Yard or Garden

Lythrum salicaria is most often found in situations where the soil is moist. However, it prefers areas with shallow water, and does not grow as prolifically in deep-water situations.


THREATS

Lythrum salicaria has the ability to completely dominate wetlands, forming a vast, monotypic stands. These stands prevent the establishment of native wetland plants. It can also have an effect on native wildlife that may not be able to use the plants as effectively for food or cover. By forming these dense stands, Lythrum salicaria can clog waterways, causing problems for both commercial and recreational uses of these areas. Lythrum salicaria can produce up to 2.5 million seeds per plant. Thes seeds persist in the seed bank for years, even if the plants themselves are eradicated from an area. This plant can hybridize with a native loosestrife, L. alatum, which is considered rare in Connecticut. With repeated hybridizations, it is possible that the gene pool for L. alatum could be depleted.


MANAGEMENT LINKS

The Nature Conservancy

Wisconsin Department of Natural Resources

The Connecticut Invasive Plant Working Group
Invasive Plant Management Guide

Plant Conservation Alliance
Fact sheet with management information


DOCUMENTATION NEEDS

Documentation required: A photograph of the plant habit, flowers or fruit.
Best time for documentation: Summer, fall.


ADDITIONAL INFORMATION

Integrated Taxonomic Information System
Taxonomic information

PLANTS Database
General information and map

The Nature Conservancy
Extensive description, biology, photographs and control information

Plant Conservation Alliance
Fact sheet that includes images and control information

Ohio Perennial and Biennial Weed Guide
Photographs and description

Wisconsin Department of Natural Resources
Description, biology and control information

National Invasive Species Information Center
Links to more information

Illinois Nature Preserves Commission
General information and control

Adirondack Park Invasive Plant Program
Identification, fact sheet, management and distribution information


REFERENCES

Anderson, M.G. 1995. Interactions between Lythrum salicaria and native organisms: a critical review. Environment Management 19: 225-231.

Anderson, N.O. and P.D. Ascher. 2000. Fecundity and fitness in cross-compatible pollinations of tristylous North American Lythrum salicaria populations. Theoretical and Applied Genetics 101 (5-6): 830-843.

Agren, J. 1996. Population size, pollinator limitation, and seed set in the self-incompatible herb Lythrum salicaria. Ecology 77 (6): 1779-1790.

Agren, J. and L. Ericson. 1996. Population structure and morph-specific fitness differences in tristylous Lythrum salicaria. Evolution 50 (1): 126-139.

Bailey, L.H. 1949. Manual of Cultivated Plants. Macmillan, New York.

Blossey, B. 1996. Lythrum salicaria, p.81. In Randall, J.M. and J. Marinelli. [eds.].  Invasive Plants: Weeds of the Global Garden. Brooklyn Botanic Garden Inc., New York.

Blossey, B., D. Eberts, E. Morrison, T.R. Hunt. 2000. Mass rearing the weevil Hylobius transversovittatus (Coleoptera : Curculionidae), biological control agent of Lythrum salicaria, on semiartificial diet. Journal of Economic Entomology 93 (6): 1644-1656.

Brown, B.J. and C.E. Wickstrom. 1997. Adventitious root production and survival of purple loosestrife (Lythrum salicaria) shoot sections. Ohio Journal of Science 97 (1): 2-4.

Britton, N.L. and A. Brown.  1970.  An Illustrated Flora of the Northeastern United States vol. 2.  Dover Publications Inc., New York. 

Crow G.E. and C.B. Hellquist. 2000. Aquatic and Wetland Plants of Northeastern North America. Vol #1. University of Wisconsin Press, Madison.

Eckert, C.G., D. Manicacci, S.C.H. Barrett. 1996. Genetic drift and founder effect in native versus introduced populations of an invading plant, Lythrum salicaria (Lythraceae). Evolution 50 (4): 1512-1519.

Edwards, K.R., M.S. Adams, J. Kvet. 1995. Invasion history and ecology of Lythrum salicaria in North America. In: Pysek, P. et al. (eds) Plant invasions: general aspects and special problems. SPB Academic Publishing, Amsterdam, pp. 161-180.

Edwards, K.R., J. Kvet, M.S. Adams. 1999. Comparison of Lythrum salicaria L. Study sites in the midwest US and central Europe. Ekologia Bratislava 18 (2): 113-124.

Farnsworth, E.J. and D.R. Ellis. 2001. Is purple loosestrife (Lythrum salicaria) an invasive threat to freshwater wetlands? Conflicting evidence from several ecological metrics. Wetlands 21 (2): 199-209.

Fernald, M.L. 1950. Gray's Manual of Botany 8th ed. American Book Co., Boston.

Gabor, T.S. and H.R. Murkin. 1990. Effects of clipping purple loosestrife seedlings during a simulated wetland drawdown. Journal of Aquatic Plant Management 28: 98-100.

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Katovich, E.J.S., R.L. Becker, D.W. Ragsdale. 1999. Effect of Galerucella sp. on survival of purple loosestrife (Lythrum salicaria) roots and crowns. Weed Science 47 (3): 360-365.

Lindgren, C.J., T.S. Gabor, H.R. Murkin. 1999. Compatibility of glyphosate with Galerucella calmariensis; a biological control agent for purple loosestrife (Lythrum salicaria). Journal of Aquatic Plant Management 37: 44-48.

Magee D.W and H.E. Ahles. 1999.  Flora of the Northeast. University of Massachusetts Press, Amherst.

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