You may wonder how we select species to appear on our web site. The species on our web site satisfy two criteria:
1)They have been observed spreading into natural areas, as non-native invaders;
2)They are species for which we have documents or original photographs.

Therefore, be advised that the species on our web site in the http://tncinvasives.ucdavis.edu domain should not, together, be construed as any kind of comprehensive "list" of invasive plants, animals, or pathogens. Conversely, the absence of a plant from our web site should not be interpreted as significant in any way--even the most dreadful invasive species would not be noted on our site if we do not have useful information about it.

Note, however, that as a service to the public we are currently hosting a weed list created by Rod Randall. This list is a compendium of information useful for those trying to determine if a plant has been observed acting as a weed. However, this list must be used carefully. Its utility and significance are carefully described there.

Furthermore, we are maintaining regional listings of invasives such as created by our colleagues at Instituto Horus. However, this kind of a weed list is not necessarily an inclusive listing of plants and animals---it is a list of organisms with demonstrably invasive characteristics in Brazil. It is not exhaustive, and species are not rated in degrees of invasiveness. For more information on these species, contact Instituto Horus.

"Lists" of non-native, invasive species are necessarily framed in the context of a specific area. A plant that is a native species in one area may be a non-native invader in another area. (For example, Andropogon virginicus is a valuable native plant in the eastern USA, but is a non-native invader in Hawai'i.) Our web site provides information on many (but not all) of the species invading natural areas within the area that The Nature Conservancy works, including North America (Canada, Mexico, USA), Latin America, and parts of Asia/Pacific.

Use the "BACK" button to return to wherever in our web site you were, and resume your research.