Still a Menace, Sterile or Not: Purple Loosestrife


 
Yes, purple loosestrife is a beautiful plant.  But it spreads quickly into the wetlands, choking out the natural growth.  them inhospitable to native plants and wildlife.  Known as the "purple plague," this invasive plant unfortunately is still sold for landscaping. A hardy European native graced with stunning spikes of  purple flowers, purple loosestrife (Lythrum salicaria) was first brought to New England in the
1800s.The plant moved rapidly north into  Canada, south into Virginia, and west through the Great  Lakes, earning it the nickname the "purple  plague." This alien now exists throughout much of     the United States; it is an especially serious threat  to wetlands in the Northeast and upper Midwest.      Purple loosestrife's swift growth and enormous reproductive capacity allow it to spread rapidly and  out compete native plants, including some  species of endangered orchids. Mature loosestrife     propagates vegetatively by root or stem segments. Also, each plant can produce millions  of tiny seeds that are carried along by wind and  water to establish new populations. As a result, many wetlands once inhabited by a rich diversity  of native plants are now overrun by dense stands of purple loosestrife-stands that can grow to  thousands of acres in size, eliminating open water habitat. The loss of native species and habitat  diversity is a significant threat to wildlife,  including several rare amphibians and butterflies,
    that depends on wetlands for food and shelter.
Purple loosestrife is still being grown and sold. It is promoted by  horticulturalists for its beauty as a landscape plant and by beekeepers as a nectar plant.
 Some U.S. plant nurseries sell cultivated  varieties of purple loosestrife that are reportedly infertile. But studies have shown that the plants are fertile and can cross with  wild strains of loosestrife. 
Taunton's Fine Gardening February 1999 Issue 65 had an interesting article on the sterile cultivars of loosestrife.
"Reportedly sterile cultivars (those that do not produce viable seed) are being sold at nursery centers across the nation.  However, Bernd Blossey, the director of the Biological Control of Non-Indigenous Plant Program at Cornell University explains that this claim is not valid. "Unfortunately, the claim that cultivars of purple loosestrife are sterile is totally false.  Research has show that if cultivars such as 'Morden Pink', 'Morden Gleam', and 'Dropmore Purple' are grown with other cultivars or wild loosestrife, the seeds are highly fertile, with more than a 90 percent germination rate.  Bees carry its pollen far and wide.  To label these plants as sterile and not a threat to the environment is misleading and irresponsible behavior on the part of those selling the plant."
The fact that some gardeners have begun to think they can grow this plant with a clear conscience has helped it stage a comeback of sorts.  Blossey adds,"One mature plant can produce over two million seeds annually that are easily transported by the wind or water into wetlands.  The seeds germinate without any special treatment, and no natural predator holds this plant in check"."
 

Some links if you would like to learn more about purple loosestrife:

 The Dirty Dozen: America's Least Wanted
 Purple Loosestrife InfoCentre 
Fighting Purple Loosestrife
 Illegal to Grow in Michigan