What is Purple Loosestrife?

Quick Facts
Name: Purple Loosestrife
Species: Lythrum salicaria
Type: Herbaceous perennial
Native habitat: Eurasia
Introduction to US: early 1800s
Height: 2 to 10 feet
Large dense plant: 50 stems; 3,000 flowers
Annual Seed Production: 250,000
Blooms: July - September
Biological control available

Purple Loosestrife labeled drawing

Purple loosestrife (Lythrum salicaria) is a herbaceous perennial that may grow up to 10 feet tall and 4 feet wide. Plants can reach maturity in 3 to 5 years, producing as many as 50 stems per plant. Leaf arrangement is opposite, alternative or in whorls of three. The leaves are lanceshaped and directly attached to stems. Stems are usually square, but may become five-or six-sided and woody as plants mature. Leaves and stems of purple loosestrife may be smooth or covered with soft hairs. The woody roots form a dense mat underground, up to 20 inches in diameter. The taproot is a major source of food for the plant that is used for regrowth when aboveground vegetation is mowed, suppressed by herbicides or damaged by insect feeding. The ability to rapidly send up new shoots gives purple loosestrife a competitive advantage over other plant species in disturbed habitats. Purple loosestrife blooms during the summer months. The reddish-purple flowers, each with 5 to 7 petals, are produced on a tall inflorescence. Purple loosestrife has three flower types, and seeds are produced between plants of different flower types. As a perennial, these plants will continue to produce seeds year after year. Purple loosestrife seeds are as small as a grain of sand and dustlike, and they are easily carried by wind or water. Seeds may also be moved about on animal fur or feathers or on muddy boots.

Where does Purple Loosestrife grow?

Purple loosestrife prefers open, sunny areas where the soil is wet. It is typically found in wet meadows, open fields, river and stream banks, floodplains, ponds, lakes and marshes. Purple loosestrife plants are also common to disturbed areas, such as roadside drainage and construction sites.

Why is Purple Loosestrife a problem?

Purple loosestrife (Lythrum salicaria) is an invasive non-native plant from Europe and Asia that was introduced into North America almost 200 years ago. The largest occurrences of this species are found in wetlands in the northeastern U.S., including all counties in Connecticut. When purple loosestrife aggressively moves into wetlands, it eliminates native plants such as cattails, sedges, bulrush and ferns. As these wetlands become infested with purple loosestrife, desirable food and nesting sites for wildlife are lost and there are fewer stopover sites for migrating birds.