You might remember that purple loosestrife (Lythrum salicaria) was all in the news 10 or more years ago. It seems that nurseries—correctly noting its pretty flower spikes, long bloom period, and low-care demeanor—were offering cultivars of this plant. Of an invasive weed, a pernicious threat to native wetlands!
For a while, various nurseries, including even the much-admired White Flower Farm of Litchfield, Connecticut sold some of the cultivars, ‘Morden Gleam’, ‘Morden Pink’, and, I think, ‘Morden Rose’. These were touted as “nearly sterile.” A fuss ensued, as “nearly sterile” is a bit like “sort-of pregnant.”
While it turned out that the cultivars were not escaping into and engulfing wetlands, and were of mixed heritage (derived from related species), they were in any event shown to be well-capable of crossing with the wildflower. (The “Morden” of all those names is the Morden Research Station in Manitoba, Canada. Plant breeders there evidently had labored out of range of the rampant wildflower and were understandably enthused about such a pretty, variable, cold-tolerant perennial.)
Purple loosestrife then went on the “banned invasives” or “watch” lists of many states, including all of New England, and as far south as Tennessee, out to Minnesota, and as far west as Oregon. I don’t think you can buy it anywhere anymore.
Where the battle to eradicate it has been undertaken, a variety of tacks have been deployed. Small infestations can usually be ripped out of the ground, before the roots become too hefty and ideally also before the plants can go to seed. Herbicides (weed killers) such as Roundup and Garlon have been used, but these carry risks to nearby plants and/or to wetland creatures, so are not ideal. Importing and releasing hungry bugs (weevils and beetles) that keep this plant in check back in its native Europe and Asia have also been tried, with mixed success.
Even though it’s no longer in the headlines, I can’t help but feel a thudding dread late every summer and fall, when I see yet another wet ditch, marsh, roadside, or lakeside where this plant has gained a foothold—it marches on. Sure, it’s pretty, especially when growing en masse. And I understand that red-winged blackbirds prefer it to cattails, and goldfinches will nest in stands.
Purple loosestrife serves to remind me, once gain, that ecology is a complicated web.