|
Purple loosestrife is a perennial distinguishable by its pretty, pinkish hue, square, ridged stem, and multiple smooth blossoms which flower continuously from June to September. The plant has an erect bearing and ranges in height from four to ten feet, depending on the variety. Further, it withstands winter temperatures and is virtually free of disease and pests.
Not a native to North America, loosestrife was introduced from Eurasia in the early 1800's by one of a variety of possible agents: the wool of imported sheep; the undersides of ships; and the suitcases of herbalists (it is said to be an effective treatment for diarrhea and sore eyes). Settlers are also reported to have imported these attractive plants for their gardens.
As a society, we normally associate alien invaders with science fiction. Yet we need look no further than the vast stretches of public wetlands, marshes, riverbanks, and pastures across North America. For these are the spots where this deceptively beautiful, hardy, pink-purple flowering plant can be found. The wild variety of purple loosestrife (lythrum salacaria) has been dubbed by federal authorities as "Public Enemy #1" among invasive weeds. The domestic varieties (cultivar) can still be purchased from garden centers in many U.S. states and Canadian provinces.
What are the characteristics of purple loosestrife that make it a menace?
1. Once the wild variety of purple loosestrife has gained a foothold, it dominates and slowly spreads, pushing out other plants and eventually altering the ecological balance of the soil, with implications for all forms of wildlife. With one plant producing as many as thirty stems, it forms a dense root mass which cannot be penetrated by other vegetation.
2. When it takes hold in ditches or irrigation channels, the water flow is disrupted, and since herbicides near water are not normally used, water flow can become blocked altogether. This is of particular concern to regions dependent upon important waterways.
3. Its very hardiness contributes to its destructive qualities. The plant is virtually impossible to eradicate since it can regenerate itself from the merest particle of root tissue remaining in the soil.
4. Gardeners may have purchased one of the varieties of this plant which is considered sterile and may be unaware of its tendency to escape from the garden to cross-pollinate with wild loosestrife, with the result that the wild species is strengthened and supported. Environmentalists also claim that it poses a threat to other garden plants, robbing them of nutrients and space.
The havoc that purple loosestrife is wreaking on the wetlands and waterways of North America has taken nearly 200 years to come to fruition. Now that the war is on, biologists are hastening to undertake long-term solutions to eradicate the plant. The following techniques are in use: hand pulling and cutting, biological control, herbicides (not close to waterways), and public notices to citizens to report loosestrife sightings in their areas.
Have gardeners been misled about this menace?
Not intentionally. Up until several years ago, some domestic varieties were thought to be safe, including popular varieties such as Morden Pink, Morden Gleam and Dropmore Purple. Their handsome appearance from June to September, an ability to grow anywhere, hardiness over the winter months, and resistance to disease and pests have made these perennials ideal for gardens. Scientific studies, however, have proved otherwise, showing that these varieties are not sterile, as originally thought, and that they can escape from gardens to cross pollinate with the wild loosestrife populations, making eradication more difficult. Each plant produces a staggering amount of seeds, up to three million annually, and since the seeds are tiny and light, the wind can carry them long distances, and bees can carry their pollen to other flowers.
Exchange programs are underway in some regions for gardeners who have managed to eradicate their plants. There are a number of attractive substitutes, for example, the Spiked Gayfeather (Liatrus), also known as The Blazing Star. It's a native perennial, similar in color and visual appeal but environmentally safe.
|
| |
