Almost as fast-moving and destructive are tree-of-heaven and non-native privets, said Jim Miller, of the U.S. Forest Service Southern Research Station.
"While our forests are besieged by numerous invasive plants, these and other non-native species present serious financial and ecological threats to the South and its forests in 2009," Miller said in a release Tuesday.
Non-native species suffocate native forest plants, destroying wildlife habitat, recreational areas, and water quality.
Miller's team has developed maps showing the spread, county by county, of more than 30 of the most invasive species across the Southeast. The maps will help forest managers and landowners anticipate where invasive species might spread next, Miller said.