purple loosestrife
(Lythrum salicaria L.)

Overview

Appearance

Lythrum salicaria is a tall, multistemmed (30-50 per plant), perennial forb that can grow up to 10 ft. (3 m) in height.

Foliage

The opposite or whorled leaves are dark-green, lance-shaped, sessile, 1.5-4 in. (3.8-10.2 cm) long and round or heart-shaped at the base.

Flowers

Flowering occurs in July to October, when pink to purplish flowers develop in 4-16 in. (10.2-40.6 cm) long spikes at the tops of the stems. Flowers have 5-7 petals and twice as many stamens as petals.

Fruit

Fruits are capsules that are enclosed in the hairy sepals and contain several reddish brown seeds.

Ecological Threat

Lythrum salicaria is a serious invader of many types of wetlands, including wet meadows, prairie potholes, river and stream banks, lake shores, tidal and nontidal marshes, and ditches. It can quickly form dense stands that completely dominate the area excluding native vegetation. This plant can spread very rapidly due to its prolific seed production; each plant can produce up to 2.5 million seeds per year. It can also hybridize with native loosestrife species, potentially depleting the native species gene pool. Lythrum salicaria is native to Europe and Asia. It was first introduced into North America in the early 1800s for ornamental and medicinal purposes.

Resources

• Best Management Practices - Ontarios Invading Species Awareness Program
• Biological Control of Invasive Plants in the Eastern United States - USDA Forest Service
• Southeast Exotic Pest Plant Council Invasive Plant Manual - SE-EPPC
• Biology and Biological Control of Purple Loosestrife - USDA Forest Service
• Weeds Gone Wild: Alien Plant Invaders of Natural Areas - Plant Conservation Alliance
• Element Stewardship Abstract - The Nature Conservancy
• Weed of the Week - USDA Forest Service
• Global Invasive Species Database - Invasive Species Specialist Group
• Plant Invaders of Mid-Atlantic Natural Areas - National Park Service and U.S. Fish and Wildlife Service
• Best Management Practices - Ontarios Invading Species Awareness Program

Selected Images

Maps

Invasive Listing Sources

• Alabama Invasive Plant Council
• Alabama Noxious Weeds - Class B Noxious Weed
• Alaska Noxious Weeds
• Alberta Fisheries Act
• Alberta Weed Control Act
• Arizona Noxious Weeds
• Arkansas Noxious Weeds - Noxious/Prohibited
• California Invasive Plant Council
• California Noxious Weeds
• City of Ann Arbor Michigan Parks and Recreation
• Colorado Noxious Weeds
• Commonwealth of Pennsylvania, Department of Conservation and Natural Resources, 1994.
• Connecticut Invasive Plant List
• Connecticut Invasive Plant Working Group
• Connecticut Noxious Weeds
• Delaware Invasive Species Council
• Delaware Invasive Species Council Invasive Species List
• Florida Noxious Weeds
• Hoffman, R. & K. Kearns, Eds. 1997. Wisconsin manual of control recommendations for ecologically invasive plants. Wisconsin Dept. Natural Resources, Bureau of Endangered Resources. Madison, Wisconsin. 102pp.
• Idaho Noxious Weeds
• Illinois Exotic Weed Act
• Indiana Invasive Species Council - Invasive Plant List
• Invasive Plant Association of Wisconsin
• Invasive Plant Species of West Virginia
• Invasive Species of Concern in Georgia
• Iowa Forest Invasive Plants
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
• Kentucky Exotic Pest Plant Council - Severe Threat
• Maine Invasive Plants
• Maryland Aquatic Nuisance Species Plan
• Maryland Cooperative Extension Service.  2003. Invasive Plant Control in Maryland. Home and Garden Information Center, Home and Garden Mimeo HG88. 4 pp.
• Maryland Department of Agriculture's Candidates for Listing of Invasive Plants
• Maryland Department of Natural Resources Policy: Restriction on Planting Exotic Invasive Plants
• Maryland Invasive Species Council - Invasive Species of Concern in Maryland
• Massachusetts Invasive Plants Advisory Group List
• Massachusetts Noxious Weeds
• Massachusetts Prohibited Plant List
• Michigan’s Prohibited and Restricted Species
• Mid-Atlantic Field Guide to Aquatic Invasive Species
• Minnesota DNR invasive species list
• Minnesota Noxious Weeds
• Missouri Noxious Weeds
• Missouri SRISP Species List
• Montana Noxious Weeds
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Native Plant Society of Oregon, 2008
• Nebraska Noxious Weeds
• Nevada EDRR
• Nevada Noxious Weeds
• New Hampshire Invasive Species Committee. 2005. Guide to Invasive Upland Plant Species in New Hampshire. New Hampshire Department of Agriculture,  Markets and Food Plant Industry Division and New Hampshire Invasive Species Committee.
• New Hampshire Prohibited Aquatic Species
• New Jersey Invasive Species Strike Team 2017 Invasive Species List
• New Mexico Noxious Weeds
• New York Regulated and Prohibited Invasive Species - Prohibited
• Non-Native Invasive Plants of Arlington County, Virginia
• Non-Native Invasive Plants of the City of Alexandria, Virginia
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• North Dakota Noxious Weeds
• Ohio Invasive Species Council
• Ohio Noxious Weeds
• Ontario’s Invading Species Awareness Program Tracked Species List
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• Pennsylvania Department of Conservation and Natural Resources Invasive Plants
• Pennsylvania Noxious Weeds
• Pennsylvania Regulations for Controlled Plants and Noxious Weeds
• Pennsylvania's Field Guide to Aquatic Invasive Species
• Plant Invaders of Mid-Atlantic Natural Areas
• Rhode Island Natural History Survey
• South Carolina Exotic Pest Plant Council
• South Carolina Illegal Aquatic Plants
• South Carolina Plant Pest List
• South Dakota Noxious Weeds
• Tennessee Exotic Pest Plant Council
• Tennessee Noxious Weeds
• Texas Noxious Weeds
• Utah Noxious Weeds - Control
• Vermont Noxious Weeds
• Virginia Invasive Plant Species List
• Virginia Invasive Species Management Plan 2012
• Virginia Noxious Weeds
• Virginia Regulations for Enforcement of Noxious Weeds Law
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States
• West Virginia Department of Agriculture Regulations Governing the Distribution of Plant Materials
• West Virginia Invasive Species Strategic Plan and Volunteer Guidelines 2014
• West Virginia Native Plant Society, Flora West Virginia Project, and West Virginia Curatorial Database System, September 3, 1999
• West Virginia Noxious Weeds
• Wisconsin Noxious Weeds
• Wisconsin's Invasive species rule – NR 40
• Wyoming Noxious Weeds

References