Purple Loosestrife – A Pretty, but Problematic, Invasive

You’ve more than likely seen purple loosestrife growing in road ditches, wet meadows, marshes, and along river and stream banks. It may look pretty, but it is invasive everywhere it is found in North America! Purple loosestrife was brought to North America in the 1800s, both intentionally as an ornamental plant, and unintentionally in ship ballast. This invasive is spread naturally through seed dispersal by wind or birds, and is also transported by animals and humans from seeds attached to fur, clothing, equipment, or vehicles.

A mature purple loosestrife plant can produce as many as 2,700,000 seeds a year, and once established, the plants form a monoculture that outcompetes our native wetland plants. Wetland animals that depend on native plants for food and shelter decline significantly. Some species, such as Baltimore butterflies, black terns, marsh wrens, and least bitterns may disappear entirely.

Purple loosestrife grows in the ditches along Compton Road, across from North Pikes Creek’s wetlands and marshes. A few of the plants were found in the marsh and removed in 2020. Friends’ volunteers have undertaken a purple loosestrife biological control project this year. A biocontrol project uses one organism to control another. In its native lands, purple loosestrife is kept in check by a species of the Galerucella beetle. For the biocontrol project, these beetles will be raised and turned loose amongst the invasive plants along Compton Road in mid-summer. The beetles will reduce both the height and seed output of the invasive purple loosestrife, enabling native plants to regain control of the affected area.

When you visit Beaver Hollow, you will be able to see the biocontrol project as it progresses!