Invasive non-native plant species (also called alien, introduced, or exotic) grow quickly and aggressively. These unwelcome plants disrupt the ecology of natural ecosystems by displacing native plants and the animal species that depend upon them, reducing native biodiversity. In this century, the greatest threat to our native plants and wildlife may well come from invasive species. The impacts of invasive species on ecosystem services have attracted worldwide attention. Despite the overwhelming evidence of these impacts and a growing appreciation for ecosystem services, however, researchers and policymakers rarely directly address the connection between invasions and ecosystem services.