Purple loosestrife was brought to the US from Europe in the early 1900s and has been spreading across the country ever since. It can now be found in at least 36 states, with this number likely growing in the future. Each plant can produce as many as 2 million seeds, which can sprout after many years of sitting dormant in the soil. The seeds’ floating properties have accelerated the rate at which the species has spread. Once established, removal is nearly impossible. No birds, mammals, or fish in North America are known to feed extensively on loosestrife, so it has turned productive wetland habitats into practically useless expanses, aside from the late season nectar that the flowers supply bees with. There has been some success with introducing a type of beetle that feeds on loosestrife in Europe, and some studies have shown 80% reductions in loosestrife abundance after several years of control with the beetles.
Loosestrife stands about four feet tall and is easily recognizable by the cylindrical purple flowers that form at the top of green stems with several individual elongated oval leaves. Native alternatives are wild beebalm, swamp milkweed, blue giant hyssop, and joe pye weed.