|
|
Invasion of the ornamentals
1 Jul, 2007 By: Brian Albright LivescapesEducation and cooperation can help stem the tide of invasives
It's well know that invasive plant species can disrupt native ecosystems, but Colorado and a few other western states are dealing with a noxious weed that sounds like something out of an old science fiction movie — not only will the plant choke-off native flora, it can actually burn people.
 INVASIVES, such as purple loosestrife, yellow toadflax, water hyacinth left to right cause numerous environmental concerns because of their threat to habitat and wildlife. |
Myrtle spurge, a blooming groundcover, has escaped from rock gardens in the west and is taking root across the countryside. Public officials have grown increasingly alarmed about the plant because its milky sap can cause burns and blisters severe enough to require medical attention.
"We started seeing it cropping up everywhere, miles away form where it was originally planted," says Cindy Lair, Colorado State Conservation Board manager. "Children were going to the hospital, and no one knew what this allergic reaction was. They had burns all over their bodies."
Myrtle spurge is just one of dozens of different types of ornamental plant species identified as invasive or noxious by federal and state authorities. These plants can strangle native plant species, depriving birds and other animals of food and nesting habitats. They can also have a significant economic impact on the agriculture industry. In some cases, invasive plants clog irrigation ditches in the water-starved West, and can practically drain wetlands. Dense growths of foreign weeds, bushes and grasses can exacerbate wildfire problems.
"They can increase the intensity and frequency of fires because they are woody, or they go dormant," says Valerie Vartanian, horticulture and landscape professions liason at The Nature Conservancy, a leading conservation organization.
 INVASIVES, such as kudzu above cause numerous environmental concerns because of their threat to habitat and wildlife. |
A Widespread Problem
Every region of the U.S. is affected. More than 2 million acres of the Florida everglades are now covered by invasive plants like the Old World climbing fern that have cut water flow by 70% and reduced wading bird populations by 95%. Pondweeds in Lake Tahoe are shading out native species and clogging boat motors. Leafy spurge is choking out native grasses in the Great Plains, threatening prime grazing land at a cost to ranchers of more than $144 million per year. Purple loosestrife, kudzu, scotch broom and water hyacinth escaped from gardens and spread rapidly.
Other common invasive plants include Tartarian honeysuckle, Russian olive, Siberian elm, Tree-of-heaven, perennial pepperweed, and yellow toadflax. The popular groundcover English ivy has also invaded forest floors in the Pacific Northwest.
Many of these plants were introduced deliberately, either by government agencies that planted them to prevent erosion or beautify roadsides, by individual gardeners, or by landscape companies or nurseries looking for exotic ornamentals. Without natural predators, the plants rapidly reproduce.
"One of the problems with invasives is that the very qualities that make it an invasive weed are the same qualities that make it a good garden plant," says Lair. "It's a prolific seeder, it reproduces by the roots, it can withstand a variety of growing conditions, or it's not real specific about soil quality."
 Russian Olive can threaten water reserves. |
Joining the Fight
Both state and federal governments have started to address the issue of invasive plants, along with invasive animal species. The National Invasive Species Council was established through an Executive Order by President Clinton in 1999, and state and regional agencies are also working to eliminate or at least contain these plants.
The major nursery and landscaping industry associations have stepped up to the plate, helping to find ways to prevent the introduction of new invasive species, and developing alternative ornamental plants.
1 2 3
Please send any technical comments or questions to our webmaster.