The tiny package of seeds promised one thing, but biology had its own agenda. Blooming with "pretty, deep purple flowers,” the popular garden retailer claimed, this striking purple beauty “will not spread all over the yard,” and, thanks to recent horticultural advancements, is “much improved…in comparison with the other varieties!”

To innocent and well-meaning gardeners, this plant, commonly known as purple loosestrife, may add a welcome burst of color to otherwise drab backyard gardens or ponds. But beneath a cheerful façade lies an aggressive invader whose distribution or sale is illegal in at least 20 states.

While purple loosestrife is still sold in nurseries and greenhouses from Montauk to Niagara Falls, its reputation as an invasive is catching on. Joining the fight against the deceptive flower, the Central & Western Chapter of The Nature Conservancy is now using an innovative technique aimed at returning balance to an ecosystem in distress.

A Marsh Monster

Purple loosestrife (Lythrum salicaria) comes from Europe and Asia and its range extends across Japan, China, India, Russia, and into Central and Western Europe. In its native habitat, loosestrife makes up but a tiny portion of the biodiversity of wetland ecosystems, and poses no economic, biological, or human threat. Populations are small and relatively well-defined, thanks to at least 100 different insect species that feed on its leaves, flowers, and roots.

The seedlings grow rapidly (sometimes over a half inch per day), and the plants can flower in their first growing season, producing more than 2.5 million seeds each year. While these facts remain the same whether the plant grows in Tokyo or Tarrytown, one factor makes all the difference: in North America, purple loosestrife has no predators.

Purple Passion

Beyond its late summer flowers, which can provide a nectar source for bees, purple loosestrife has few redeeming qualities. It does, however, create a host of problems.

When purple loosestrife invades wetlands, it suppresses native plant communities leading to a change in the wetland’s structure and function. Large, monotypic stands jeopardize threatened and endangered plants and wildlife, such as the spikerush in New York, and the bog turtle in the Northeast.

It also eliminates sources of food and shelter that are essential to some wildlife. Black terns, once a common species at the Montezuma National Wildlife Refuge, have declined significantly since purple loosestrife became established at the refuge in the 1980s.

Researchers at Cornell have also found that purple loosestrife changes the chemistry of the water, slowing the development of frog tadpoles and decreasing a frog’s chances of growing large enough to survive its first winter.

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Nature picture credits (top to bottom, left to right): Photo © Randy Westbrooks, USGS (Purple loosestrife for sale); Photo © The Nature Conservancy (Purple loosestrife)