Alien Species In Hawaii Information Index
http://www.hear.org/AlienSpeciesInHawaii/index.html

Aquatic, Wetland and Invasive Plant Information Retrieval System (APIRS)
http://aquat1.ifas.ufl.edu/

Bay Grass Identification Key
http://www.dnr.state.md.us/bay/sav/key/

Center for Aquatic and Invasive Plants
http://aquat1.ifas.ufl.edu/

Changing Patterns in the Number of Species in North American Floras (USGS)
http://biology.usgs.gov/luhna/chap4.html

Florida Exotic Pest Plant Council
http://www.fleppc.org/

Hawaiian Alien Plant Studies
http://www.botany.hawaii.edu/faculty/cw_smith/aliens.htm

Hawaiian Ecosystems at Risk Project (HEAR)
http://www.hear.org/

INVADERS (Univ. of Montana)
http://invader.dbs.umt.edu/

Invasive alien species: USGS/NBII
http://www.invasivespecies.gov/

Invasive Exotic Plants
http://www.fnps.org/

Invasive Exotics Plant Pictures
http://www.nsis.org/gallery/pl-invasive.html

Leafy Spurge web site
http://www.team.ars.usda.gov

Minnesota Sea Grant Exotic Species
http://www.seagrant.umn.edu

National Agricultural Pest Information System (NAPIS)
http://ceris.purdue.edu/napis/

New Zealand Invasive Species
http://www.issg.org/

Nonindigenous Aquatic Species by USGS
http://nas.er.usgs.gov/

North American Plant List Database
http://plants.usda.gov/

Submerged Aquatic Vegetation in Chesapeake Bay
http://www.vims.edu/bio/sav/

Weeds gone wild (Alien plant invaders of natural areas) (National Park Service)
http://www.nps.gov/plants/alien/

Western US Weed Information
http://www.weedcenter.org/