Those who are more familiar know purple loosestrife as the purple plague, phragmites as a mighty intruder, and an infestation of bittersweet as far from sweet.
In fact, invasions of non-native plants are the second most significant threat to the integrity of our nation's natural areas, behind habitat fragmentation. The New England Wildflower Society reports that invasive species have cost the American economy more than $138 billion per year in environmental damage, crop failures, control efforts and public health problems.
While this news may seem daunting, there is much that each of us can do to prevent further spread or new infestations of these nefarious neighbors. The first step is to know just what an invasive plant is.
Most invasives originate from far-away places, such as Asia, Eurasia and Europe. Some were introduced for horticultural reasons, others were brought here for conservation purposes - such as wind breaks, or as food and cover for wildlife - and still others came as stowaways in packing materials or in the ballast of ships.
Wherever they come from and however they got here, they all share certain traits: they are non-native, they move aggressively into a habitat, and they monopolize resources such as light, nutrients, water and space to the detriment of other species.
In general, the areas most severely affected by invasives are those on or near the coast. Essex County, which is largely within coastal range, has more than its share. Common examples include burning bush (Euonymus alatus), glossy buckthorn (Frangula alnus), purple loosestrife (Lythrum salicaria), Japanese barberry (Berberis thunbergii), Norway maple (Acer platanoides), and water chestnut (Trapa natans). The accompanying photos and captions will help you identify two of these invasive plants.
While most native plants have predators that keep population numbers in check, these newly introduced species arrive unimpeded. In addition, many invasives produce significantly more seed than their native competitors, increasing their chances of expansion. Also, invasives often have more aggressive root systems, and can grow in varied conditions, and therefore out-compete less hardy natives. Any of you who have dealt with Japanese knotweed, for example, understand these characteristics all too well. Knotweed can send out roots as long as 65 feet. If cut, the remaining root will send up new shoots along its entire length. These shoots will then push their way up through just about any surface (even asphalt!) and grow in sun or shade, as well as in rich or poor soil.
For most of us who live in Essex County, a walk through the neighborhood, or even your own backyard, will turn up one or more invasive plants. To deal with such overzealousness, your best bet is to take a slow, determined approach. Think in terms of years, not days or months, to fully exterminate the interloper from your area. A plethora of information is available about the varied approaches to conquering invaders. Visit www.mass.gov/masswildlife for general information about invasives and links to other sites.
One important strategy is to identify and eliminate any new invaders before they take hold. Doing so can dramatically reduce the expense of eliminating the intruders and significantly improve the chances of preventing them from spreading.
In recent years, the Essex County Greenbelt Association has collaborated with the New England Wildflower Society to eradicate newly established species of water chestnut from Upper Mill Pond in Rowley. Every June, July and August, NEWFS volunteers will venture out on the pond by canoe and pull out the proliferous plant by hand, until the plants are completely gone. To help with this effort, we invite you to attend NEWFS's work day this summer.
For information about how you can help with this and other Greenbelt efforts to eliminate invasive species, call Dave Rimmer at 978-768-7241, ext. 14, or visit Greenbelt's Web site at www.ecga.org.
Jill Buchanan is a marketing consultant for the Essex County Greenbelt Association.