Purple loosestrife has a well-deserved place on the Most Unwanted List for invasive plants in New York, but its beauty makes it a tough target for those seeking to maintain native ecosystems.
The flowering plant, with the scientific name Lythrum salicaria, is native to Europe and Asia but has developed a mixed reputation since it arrived in North America in the early 1800’s.
Once it gains a foothold in North American wetlands, it tenaciously spreads, pushing out native species like cattails. In some places the purple perpetrator has taken over areas as large as 1,500 acres and left bog turtles homeless in its wake.
The plant’s beauty masks its durability. Purple loosestrife’s downy, smooth-edged leaves cover spikes that deter grazers. With no natural predators, it has bested wetlands from Canada to the coast of California.
According to purpleloosestrife.org, the most effective response has been to go to war with beetles. Following rigorous testing, four species of beetles were introduced to habitats of purple loosestrife. These included two leaf-feeding beetles, one root-boring weevil and one flower-feeding weevil.
Galerucella pusilla and G. calmariensis are leaf-eating beetles which seriously affect growth and seed dispersal.
Hylobius transversovittatus is a root-boring weevil that deposits its eggs in the lower stem of purple loosestrife plants.
(Hylobius transversovittatus, a species of weevil known to consume purple loosestrife)
The flower-feeding weevil, Nanophyes marmoratus, severely reduces seed production of purple loosestrife.
However, purple loosestrife has found defenders in some unlikely corners. Beekeepers have backed loosestrife, pointing to losses in honey revenue if the flowering plant is beaten back.
One of the goals of the Plant Don’t Plant project is not to fight so much as to render the plant irrelevant by listing alternative native species such as the spiked gayfeather or the little princess.
Alternatives to this purple invader are available on the cceulster.org website, where a New York hotline is also listed.