Invasive Species (Aquatic) -


Purple loosestrife
(Lythrum salicaria L.)

Photos & Description courtesy of IPANE

What Purple loosestrife does to the habitat

Loosestrife can completely dominate a habitat, forming dense stands and pushing out all native plants and many animals. The plant can produce more than 2 million seeds a year which last for years in the seed bank.


It already covers millions of acres in the U.S. Threatened are muskrats, bog turtles, black terns, bulrush and flowering rush.


The dense stands clog waterways causing damage to commercial and recreational use of the land as well as to the natural habitat.



Small stands you can pick by hand or use a weed wrench. Be sure to do it before the seeds set and bag all the plant parts. Mowing is not a good idea as it tends to spread the plants.


You can cut them, but since that leaves the root, you will have to follow up with more cutting until the roots starve. Bag all plant parts. Round Up and Rodeo also work on loosestrife.


There are 4 interesting biological controls, that is insects that eat purple loosestrife. Two leaf-eating beetles, Galerucella calmariensis and G. pusilla defoliate purple loosestrife. And there are 2 weevils that also eat the plant.


For more information about biological control of purple loosestrife, contact:

Donna Ellis
Dept. of Plant Science, Box U4067
University of Connecticut, Storrs, CT 06269
Tel: (860) 486-6448


Common Name

Full Scientific Name

Purple loosestrife

Lythrum salicaria L.

Family Name Common

Family Scientific Name

Loosestrife family Lythrum salicaria


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.

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