Oh No! Not My Wisteria!
On Morning Edition, Ketzel Levine talks about invasive exotic plants, many of which are still sold in nurseries and coveted by unsuspecting gardeners.
March 21, 2002 -- The more I learn about the problem of invasive exotic plants, the less I'm sure of what to do. I know that pampas grass (Cortaderia selloana) is big trouble in coastal California; does that mean I should remove the variegated form from my yard? Now that Japanese barberry (Berberis thunbergii) is smothering woodlands in Massachusetts, should Pacific Northwest gardeners take heed and shun further use of the plant?
I'm not going to dummy this down for you, and say Here Are The Rules. As yet, there are no rules, until the sale of a particular plant becomes illegal in your state. Then, at least, you know what not to do (and, presumably, so does your local nursery).
But by the time a plant is quarantined, the damage is long done; waiting for state or federal intervention is not the way to go. Our job as gardeners is to stay one step ahead of the problem, by paying attention to which plants are potentially invasive, and using better-behaved alternatives.
Let's face it, you know all too well when a plant's too good to be true. If it flowers fast and makes tons of seeds... tolerates drought, flood, sun and shade... sends out runners the minute you turn your back and shows up all over the yard... Give It Up.
Native, non-native, it's poTAYto, poTAHto to me (let's not get into a fight here, please; there's too much hard work to do). Here's what I'm advocating: non-invasive, gardenworthy plants.
What You Can Do
Get smart. Check out both your own state's and your neighboring states' invasive plant lists. If clary sage is already a problem in Washington, it's a safe bet it'll soon be one in Oregon.
Get busy. If you live on the edges of natural areas (which in many cases will already be far from pristine), and the plants you're growing are spreading like mad, either compost them (if you're not worried about seeds spreading) or shove them in a garbage bag and let them rot. If your favorite nursery is selling a known invader, ask them to start offering alternatives. When your neighbor wants advice on a groundcover, steer them away from ivy!
Get involved. Follow some of the links provided here to get a grasp of the enormity of the problem, then check out what local groups are doing. You don't have to join them, just learn from them. The information that awaits you is mind-boggling.
And Away We Go
Please note there are lots more where these came from!
The Nature Conservancy's Invasives on the Web includes an interactive map showing invasive plants specific to different regions, a large library of information on controlling invasive plants in your garden, and an extensive photo gallery of invasive species.
The Center for Plant Conservation is a cooperative network of botanic gardens and arboreta dedicated to the preservation and restoration of native U.S. species. The Workshop on Linking Ecology and Horticulture to Prevent Plant Invasions is a continuing seminar seeking to develop voluntary approaches for reducing the introduction and spread of invasive plants.
The Ivy Removal Project is the site for Portland's No Ivy League. Consider starting one in your neighborhood!
Invasivespecies.gov is the gateway to Federal efforts concerning invasive species.
The Bugwood Network is managed by the College of Agricultural and Environmental Sciences at the University of Georgia in Tifton. Another great gateway.
The Invasive Web site a University of Georgia endeavor, includes an accessible archive of images related to invasive species.
The Plant Conservation Alliance's Weeds Gone Wild is a government-hosted site including a national list of invasive plants infesting natural areas throughout the United States.
The Non-Native Invasive Aquatic and Wetland Plants list is a multi-University project offering a handy interactive map that takes you deeper into state-by-state weed lists and controls.
Regionally Specific Web sites:
The North Carolina Botanic Garden Invasive Exotic Plants Web site is a prototype of what may soon be in the offing from botanic gardens across the country: regionally specific, easy-to-use lists of dubious and disastrous invasive plants. If your botanic garden isn't doing this, let them know you'd value the service.
Native plant societies across the country are getting into the act, and the Maryland NPS Web site is another good protytpe. Be sure to check your own local native plant society for more information on local invasive exotics, but remember, it's not simply about replacing exotic plants with native plants, it's about using good plants.
Check for your own state's The Exotic Pest PlantCouncil. This one is a collaboration between the Missouri EPPC and the Missouri Botanic Garden. One can see a worksheet rating the relative danger of invasive plants, view images of the plants, their distribution throughout the state, and recommended control techniques.
The The New England Wild Flower Society offers a comprehensive list of books and links for the Northeast gardener.
St. Johnís Wort
A Natural History of Exotics in America
Janet Marinelli and John Randall
Brooklyn Botanic Garden Handbook, 1996
Tinkering with Eden: A Natural History of Exotics in America
W.W. Norton, 2001
Alien invasion: America's Battle with Non-native Animals and Plants
National Geographic Society, 1998
Life Out of Bounds: Bioinvasion in a Borderless World
W.W. Norton & Co., 1998
Nature Out of Place: Biological Invasions in the Global Age
Jason Van Driesche and Roy Van Driesche
Island Press, 2000
A Plague of Rats and Rubbervines: The Growing Threat of Species Invasion
Island Press, Washington, DC (available soon)
The Ecology of Invasions by Plants and Animals
Charles S. Elton
Chapman & Hall, 1958
This is the book that many credit with first calling scientific attention to the issue of invasives. After 44 years it still commands respect and is well worth reading.
Strangers in Paradise: Impact and Management of Non-indigenous Species in Florida
Daniel Simberloff, Don C. Schmitz & Tom C. Brown (eds.)
Island Press, 1997
For Land Managers in California and Surrounding States:
Invasive Plants of California's Wildlands
Carla C. Bossard, John M. Randall and Marc C. Hoshovsky (editors)
University of California Press, 2000
Alteration of Native Hawaiian Vegetation: Effects of Humans, Their Activities and Introductions
Linda W. Cuddihy and Charles P. Stone
University of Hawaii Cooperative National Park Services Unit, 1990
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