Threat of Invasive Plants
Invasive plant species are a threat to natural areas in Indiana. They displace native plants, eliminate food and cover for wildlife, and threaten rare plant and animal species. However, among natural resource professionals there is little consensus on which species constitute the greatest threat to natural areas. Consequently, species that are considered a grave threat by some resource professionals are still recommended by other resource professionals and sold by nurseries.
Due to the threat invasive plants pose to natural areas around Indiana, INPAWS endorses the recommendations of the Invasive Plant Species Assessment Working Group (IPSAWG) and asks this of the INPAWS membership:
1. Do not buy, sell, recommend, or plant species designated as invasive by IPSAWG (as posted on www.invasivespecies.in.gov); and
2. Actively work to remove these species from landscapes around Indiana with permission of the landowner.
What’s an Invasive Plant?
The federal definition of invasive species is a non-native species whose introduction causes or may cause economic or environmental harm or harm to human health.
Of the roughly 2,300 plant species growing outside cultivation in Indiana, approximately 25 percent are non-native. While most of these non-native plants cause little trouble, some of them are invasive and are responsible for degrading and destroying thousands of acres of natural plant communities in Indiana. Control efforts for these invasive species are costing taxpayers hundreds of thousands of dollars each year.
Unfortunately, some of the worst invasive plants are still being sold by nurseries and planted by well-meaning Hoosiers, not realizing the problems they can cause. The good news is that there are non-invasive alternatives to these garden thugs.
Why Should We Care?
Invasive species cost the US over $138 billion per year.
Approximately 42% of threatened or endangered species are classified “at risk” due directly to non-native invasive species.
In the US, approximately 9% of forest products—worth a total of $7 billion per year—are lost as a result of non-native plant pathogens.
To date, about 5,000 types of alien plants are found in US ecosystems.
Alien weeds invade 1,730,000 acres of wildlife habitat per year in the US.
There are 180 non-indigenous aquatic species in the Great Lakes ecosystem. Of these, 15% cause serious harm. (ISCC Facts)
Landscaping without Invasive Plants
We recommend three brochures for anyone who wants to plant an invasive-free landscape:
Landscape Alternatives for Invasive Plants of the Midwest, prepared by the Midwest Invasive Plant Network. Download brochure
Landscaping with Non-Invasive Plant Species: Making the RIGHT Choice, prepared by the Invasive Plant Species Assessment Working Group. The list includes ornamental non-native plants that mingle with natives without doing harm. Download brochure
Invasive Plants in Indiana: Their Threat and What You Can Do, defines invasive plants and why we should care about them, provides details about the worst invaders, and suggests additional resources. A joint effort of INPAWS, The Nature Conservancy, IDNR Division of Nature Preserves, Indiana Invasive Plant Species Assessment Working Group, and Natural Resources Conservation Service. Download brochure
For large orders of any brochure, please pre-order at cost. Call The Nature Conservancy at 317-951-8818 or email Ellen Jacquart.
More About Invasive Plants
For more information on invasive and native plants, visit these sites:
Invasipedia houses information on invasive plants, animals, and pathogens, and especially how to best manage them. Its foundation is the large amount of species management information developed by the The Nature Conservancy’s Global Invasive Species Team.
Weeds Gone Wild: Alien Plant Invaders of Natural Areas A web-based project of the Plant Conservation Alliance’s Alien Plant Working Group. Provides information for the general public, land managers, researchers, and others on the serious threat and impacts of invasive alien (exotic, non-native) plants to the native flora, fauna, and natural ecosystems of the United States.
Invasive Plant Atlas of the United States A collaborative project between the National Park Service, the University of Georgia Center for Invasive Species and Ecosystem Health, the Invasive Plant Atlas of New England, and the Lady Bird Johnson Wildflower Center. Assists users with identification, early detection, prevention, and management of invasive plants. The focus is on non-native invasive plant species impacting natural areas, excluding agricultural and other heavily developed and managed lands. Four main components are species information, images, distribution maps, and early detection reporting procedures.
IDNR Invasive Exotic Plants in Indiana Natural Areas A list of the most troublesome non-native plants that have been observed occurring in natural communities. Compiled by state botanist Mike Homoya and updated periodically to include newly discovered invasive species.
Early Detection & Distribution Mapping System (EDDMapS) A web-based mapping system for documenting invasive species distribution from databases, organizations, and volunteer observations. The aim is to create a national network of invasive species distribution data that is shared with educators, land managers, conservation biologists, and beyond. Includes county-by-county sightings.