Non-native plants are a conspicuous part of the Texas landscape, from lawns and roadsides to relatively undisturbed natural communities. Currently, Texas hosts nearly 800 of these species, which are native to various parts of the world, including Asia, Europe, and Central America and South America. Many are invasive and pernicious weeds, crowding or replacing native flora; others appear more benign, mostly restricted to sites that are heavily disturbed or else known only from one or a few places. Of course, some of the most recently arrived species in our state may ultimately become "noxious" invasives. Many are naturalized and irretrievably established in Texas, so much so that we may begin to regard them as "native," and the future will see many more extra-North American species become established and abundant.
Information on non-native species in Texas is provided here in several accounts:
* Non-native species recorded to occur in Texas from 1980 to the present, listed alphabetically and including the literature reference and county (counties) of reported occurrence.
* All non-native species recorded for Texas, arranged alphabetically by family, genus, and species.
* Lists of noxious and exotic species from Texas Dept. of Agriculture and Texas Parks and Wildlife Dept.
Also see links to informative websites and pages relevant to Texas invasive species.
What Is an “Invasive Species”?
As legally defined, an invasive species is “An alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health …. ‘Alien species’ means, with respect to a particular ecosystem, any species … that is not native to that ecosystem.” Alien species are also known as exotic, non-native, introduced, or non-indigenous species, and the term noxious or nuisance is sometimes used instead of “invasive” when these organisms cause harm. Although they are “natural” and because at times they can spread very slowly, over years or even decades, invasive species cause a range of problems. They can
• threaten the survival of native plants and animals
• interfere with ecosystem functions
• hybridize with native species, resulting in negative genetic impacts
• spread easily in today’s era of global commerce
• be difficult and costly to control
• impede industries and threaten agriculture
• be a significant drain on the economy
• endanger human health
(from "Invasive Species of Texas," Union of Concerned Scientists, 1999)
* Which non-native plants are included in floristic accounts?
Four terms provide a general description of the major categories of non-native plants in our flora: cultivated, persisting, waif, and naturalized. Comparative definitions are provided for seven related terms that describe the non-native origin and floristic integration of vascular plant species in North America: adventive, alien, escaped, established, exotic, introduced, and non-native. (Nesom, G.L. 2000. Sida 19:189-193.)
