Officials in the United States Department of Agriculture (USDA) have determined that certain species not native to the United States are at risk of becoming invasive should they enter this country. As part of its effort to prevent the introduction of invasive or potentially invasive weeds, the USDA maintains an official list of "federal noxious weeds" (FNW) (7 CFR 360.200 and 361.6). Many taxa on this list are currently serious weeds elsewhere in the world, and about two-thirds of the taxa are currently found in the United States. The list includes terrestrial, aquatic, and parasitic plants. Most of the FNW are angiosperms, but a few are aquatic ferns and one is a green alga. Importation or transport across state lines of the taxa on the FNW list is prohibited.

Note that these FNW taxa, as well as other taxa in this tool that are not FNW, may be listed as noxious weeds in various U.S. states, or in other countries.

In the list below, two species (Melaleuca quinquenervia and Solanum tampicense) are not covered in this tool because no species in the genera to which they belong are traded as aquarium or pond plants. Links for these two species will take you to a page of images, not to a fact sheet in this tool.

* Mimosa pigra is considered a terrestrial plant on the federal noxious weed list.