An invasive plant is ” an alien species (non-native) whose introduction does or is likely to cause economic or environmental harm or harm to human health.”
Highly invasive plants that are threats particularly to agricultural production and clog waterways are considered ‘noxious‘. These plants are highly regulated and are illegal to buy, sell, or grow.
Why are invasive and noxious plants a problem?
According to the United States Forest Service invasive and noxious weeds are a problem for the following reasons:
- Invasive species have contributed to the decline of 42% of U.S. endangered and threatened species, and for 18% of U.S. endangered or threatened species, invasives are the main cause of their decline.
- Invasive species compete directly with native species for moisture, sunlight, nutrients, and space.
- Overall plant diversity can be decreased
- Establishment and spread of invasive species can degrade wildlife habitat
- Results in poor quality agriculture lands
- Degraded water quality
- Increased soil erosion
- Decreased recreation opportunities
These impacts change nature’s balance on which all species depend.
Invasive plants were brought to the United States for ornamental reasons, as forage for livestock, and for soil stabilization. Many of these plants arrived accidentally on ships or other means of transport and are spread by people, birds, and other animals accidentally carrying seeds on clothing and fur.
Some Landscape Plants Considered Invasive
We tend to think of invasive plants as undesirable weeds, however, many popular landscape plants are considered invasive.
Some states have made certain landscape plants illegal to sell. For instance, the state of New Hampshire has banned the sale of burning bush, Norway maple, and Japanese barberry.
Some plants may be considered more invasive in some parts of the country than others. For instance, water hyacinth does not survive freezing winters but is invasive in the southern US. Some invasive plants can be controlled with time and effort.
Recommendations
The National Arboretum recommends following these steps to reduce the amount of non-native invasive species in the landscape:
- Contact your local native plant society or state Department of Natural Resources to find out which plants are invasive in your area
- Lots of information is available on the Internet
- Learn to identify locally important invasive plants
- Remove invasive plants on your property or prevent their spread
- Only use non-invasive plants when landscaping your property
- If your property borders a natural area, consider using only native plants in your landscape
- Find non-invasive or native alternatives for invasive landscape plants
- Use systemic herbicides carefully as a last resort to remove invasive plants
- Make others in your neighborhood aware of invasive plants
General Information:
Center for Invasive Species and Ecosytem Health
National Invasive Species Information Center: United States Department of Agriculture National Agricultural Library
National Resource Conservation Service (NRCS)
Additional Resources by Region:
West
Washington: The Myth of Well-Behaved Ornamentals
Northeast
New York: Alternatives to Ornamental Invasive Plants
Maryland: Invasive Plants Cause Ecosystem-Level Changes
Midwest
Indiana: State Noxious Weeds List
Southeast
Tennessee: Tennessee’s Native Plant Alternatives to Exotic Invasives A Garden & Landscape Guide