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National Invasive Species Information Center
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Home » Species Profiles » Aquatic Invasives » Aquatic Plants » Alligatorweed

Alligatorweed

Alligatorweed
Scientific Name:
Alternanthera philoxeroides (Mart.) Griseb. (ITIS)
Synonym:
Achyranthes philoxeroides (ITIS)
Common Name:
Alligatorweed, alligator weed, pig weed
Photo:
Alligatorweed, flower - Photo by Chris Evans; University of Illinois
Native To:
South America (Spencer and Coulson 1976)
Date of U.S. Introduction:
First reported in Alabama in 1897 (Masterson 2007)
Means of Introduction:
Probably introduced through ballast water (Masterson 2007)
Impact:
Forms dense mats that crowd out native species and impede recreational activities such as boating, swimming, and fishing (Texas Invasives 2007)
Current U.S. Distribution:
Southeastern U.S., California

Distribution/Maps/Survey Status

Images

Videos

Selected Resources

The section below contains selected highly relevant resources for this species, organized by source. To view all related content for this species, click on "View all resources for species" in the top left of this page.

Partnership

EPPO Global Database - Alternanthera philoxeroides
European and Mediterranean Plant Protection Organization.
Global Invasive Species Database - Alternanthera philoxeroides (aquatic plant, herb)
IUCN. Species Survival Commission. Invasive Species Specialist Group.
Invasive Plant Atlas of the United States - Alligatorweed
University of Georgia. Center for Invasive Species and Ecosystem Health.
Invasive Species Compendium - Alternanthera philoxeroides
CAB International.
Pacific Island Ecosystems at Risk (PIER) - Alternanthera philoxeroides
USDA. FS. Institute of Pacific Islands Forestry.
Plantwise Technical Factsheet - Alligator Weed (Alternanthera philoxeroides)
CABI. Plantwise Knowledge Bank.
Texas Invasives Database - Alternanthera philoxeroides
TexasInvasives.org.
The Quiet Invasion: A Guide to Invasive Species of the Galveston Bay Area - Alligatorweed, pig weed

Texas Commission on Environmental Quality, Galveston Bay Estuary Program; Houston Advanced Research Center (HARC).

Federal Government

Indian River Lagoon Species Inventory - Alternanthera philoxeroides
Smithsonian Institution. Smithsonian Marine Station at Fort Pierce.
National Exotic Marine and Estuarine Species Information System (NEMESIS): Chesapeake Bay Introduced Species Database - Alternanthera philoxeroides
Smithsonian Institution. Smithsonian Environmental Research Center. Marine Invasions Research Lab.
Nonindigenous Aquatic Species Database: Fact Sheet - Alligatorweed
DOI. USGS. Wetland and Aquatic Research Center.
Provides distribution maps and collection information (State and County).
PLANTS Database - Alligatorweed
USDA. NRCS. National Plant Data Center.
U.S. National Plant Germplasm System - Alternanthera philoxeroides
USDA. ARS. National Genetic Resources Program. GRIN-Global.

International Government

NSW WeedWise: Alligator Weed
New South Wales Department of Primary Industries (Australia).
Invasive Plants: Restricted Invasive Plants - Alligator Weed
Queensland Business and Industry Portal (Australia).
Weeds in Australia - Alligator Weed (Alternanthera philoxeroides)
Australian Government. Department of the Environment and Energy.
Designated Weed of National Significance
Weeds of National Significance: Weed Management Guide - Alligator Weed (2003)
Cooperative Research Centre for Australian Weed Management.

State and Local Government

Encycloweedia: Data Sheet - Alligatorweed
California Department of Food and Agriculture.
See also: Included on California's noxious weed list; see Encycloweedia: Program Details for additional resources
Illegal Aquatic Plants - Alligatorweed
South Carolina Department of Natural Resources. Aquatic Nuisance Species Program.

Academic

AQUAPLANT - Alligator Weed
Texas A&M University. AgriLife Extension Service. Department of Wildlife and Fisheries Sciences.
Plant Profile: Alternanthera philoxeroides
University of Florida. IFAS. Center for Aquatic and Invasive Plants.

Citations