While quite attractive, purple loosestrife is a non-native invasive plant species. It is considered invasive because it spreads prolifically, a single plant producing over 1 million seeds. Growing in dense clumps that can reach heights of over 6ft, they prevent sunlight from reaching native plants that grow closer to the ground. As such purple loosestrife is capable of rapidly displacing native species of plants.
The above photograph illustrate the extent of purple loosestrife infestation in one of the interdunal wetlands along the Miller Woods trail.
This is what the infestation looks like from within the wetland itself. You can see how the purple loosestrife towers over the rest of the vegetation. Left unchecked it will eventually starve out the native species.
At the Indiana Dunes National Park, staff and volunteers are working to remove the flowers of purple loosestrife before they release their seeds, thus slowing their spread. There are several species of beetles and weevils that aggressively feed on purple loosestrife and which can be introduced to help with eliminating existing plants.
References
New York Invasive Species (IC) Information, https://nyis.info/species/purple-loosestrife/, (Accessed 08/17/2026).
Invasive Species Centre, https://www.invasivespeciescentre.ca/invasive-species/meet-the-species/invasive-plants/purple-loosestrife/, (Accessed 08/17/2026).
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