Introduced species are those species moved by humans from their native location to another location. Most often the species are introduced for agricultural or landscaping purposes or as sources of timber, meat, or wool. Invasive plants have often been thought to succeed because they have escaped their natural enemies, primarily insects that remained in the country of origin and were not transported to the new locale. In the 21st century, they have become a serious economic, social and environmental threat. Invasive plant species can spread rapidly with negative consequences for native...