Purple Loosestrife
Lythrum salicaria
A bumblebee visits an invasive purple loosestrife plant growing along the shoreline of Havre de Grace, Md., on July 25, 2016. Purple loosestrife is an invasive species from Europe and Asia that can invade freshwater wetlands and crowd out native plants that provide ideal habitat for a variety of waterfowl and other wetland animals. (Photo by Will Parson/Chesapeake Bay Program)
Purple loosestrife has spikes of bright purple or magenta flowers that bloom in mid- to late summer. (Gertrud K./Flickr)
Purple loosestrife spreads quickly in disturbed fresh and brackish wetlands and other moist or marshy sites. (InAweofGod'sCreation/Flickr)
Purple loosestrife grows in moist, disturbed areas, including ditches and roadsides. (Jerry Oldenettel/Flickr)
Purple loosestrife quickly establishes itself and crowds out native wetland plants. (Lisa Ruokis/Flickr)
Purple loosestrife grows in colonies in wetlands and other moist or marshy areas. (Lisa Ruokis/Flickr)
Purple loosestrife is an invasive perennial plant with spikes of bright purple flowers that bloom in mid- to late summer.
Appearance
Purple loosestrife has spikes of bright purple or magenta flowers that bloom in July to September. Its stems are square and six-sided. Long or lance-shaped leaves grow up to 4 inches long and are arranged in pairs or whorls of three along the stems. In autumn, the leaves often turn red for about two weeks before fading and falling off. Purple loosestrife can grow to six feet tall.
Reproduction and Life Cycle
Purple loosestrife spreads rapidly via seeds, roots and stem fragments. A single mature plant can produce more than 2 million seeds per year. Wind, water and animals spread the seeds, which grow into new seedlings the following spring. It can reproduce asexually when its thick, fleshy roots produce new shoots, allowing the plant to spread about one foot per year. New plants can also grow from stem fragments when plants are cut or mowed down.
Did You Know?
- Purple loosestrife spread to the U.S. in the 18th and 19th centuries when ships inadvertently carried the plant’s tiny seeds in their ballast and shipments. It was also introduced purposefully in certain areas because of its beauty and value as a healing herb.
- It is considered to be invasive because it grows rapidly, produces many seeds and has no natural predators. The plant quickly establishes itself and crowds out native wetland plants.
- Never plant any variety of purple loosestrife in your garden. Even seed-free varieties can cross-breed with invasive strains to make seeds.
Sources and Additional Information
- Plant Invaders of Mid-Atlantic Natural Areas: Purple Loosestrife – U.S. Fish & Wildlife Service
- USDA PLANTS Profile for Lythrum salicaria – USDA Natural Resources Conservation Service
- Purple Loosestrife – Dave’s Garden
Quick Facts
Species
Invasive
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Size
6 feet tall -
Habitat
Grows in colonies in disturbed fresh and brackish wetlands and other moist or marshy sites, including ditches, roadsides, wet meadows, and along the edges of ponds, rivers and reservoirs.
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Range
Native to Europe and Asia; found throughout the Chesapeake Bay watershed.
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Status
Stable