| alligatorweed |
USDA PLANTS Symbol: ALPH USDA ARS GRIN: 101502 ITIS: 20770 NAPIS: PAFABBA |
| Alternanthera philoxeroides (Mart.) Griseb. | |
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Taxonomic Rank: Magnoliopsida: Caryophyllales: Amaranthaceae |
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| Synonym(s): alligator weed, pig weed | |
Alligatorweed is an emergent or rooted floating plant that invades aquatic areas and adjoining uplands throughout the southern portions of the United States. Plants have hollow stems and can grow to 3 ft. (1 m) tall. Opposite, elliptical leaves are thick but non-succulent and are up to 4 in. (10 cm) long. Flowering occurs during the summer with white, clover-like heads in the axils of the leaves. Alligatorweed roots in wet soils or shallow water and grows out into waterways. Alligatorweed can also grow terrestrially, forming smaller, tougher leaves. The thick mats can displace native vegetation and wildlife habitat, clog waterways, restrict oxygen levels of water, increase sedimentation, interfere with irrigation and prevent drainage. Alligatorweed is native to South America and was first introduced into the United States around 1900 in ballast water. |
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Identification, Biology, Control and Management Resources
- Images, Video and Information - University of Florida - Center for Aquatic and Invasive Plants
- Global Invasive Species Database - Invasive Species Specialist Group
- Invasive Alien Plant Species of Virginia - Virginia DCR and Virginia Native Plant Society
- Biological Control of Invasive Plants in the Eastern United States - USDA Forest Service
| Selected Images from Invasive.org | View All Images at Invasive.org |
 Flower(s); the white flowers are arranged in stalked, short, headlike spikes, and have a style Gary Buckingham, USDA Agricultural Research Service, Bugwood.org Additional Resolutions & Image Usage |
 Flower(s); Chris Evans, River to River CWMA, Bugwood.org Additional Resolutions & Image Usage |
 Flower(s); Robert H. Mohlenbrock, USDA NRCS PLANTS Database, Bugwood.org Additional Resolutions & Image Usage |
 Flower(s); Richard Old, XID Services, Inc., Bugwood.org Additional Resolutions & Image Usage |
 Foliage; Chris Evans, River to River CWMA, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); in flower Richard Old, XID Services, Inc., Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); James H. Miller, USDA Forest Service, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); in flower Chris Evans, River to River CWMA, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); Chris Evans, River to River CWMA, Bugwood.org Additional Resolutions & Image Usage |
 Infestation; Chris Evans, River to River CWMA, Bugwood.org Additional Resolutions & Image Usage |
 Infestation; Chris Evans, River to River CWMA, Bugwood.org Additional Resolutions & Image Usage |
 Diagram or Graphic; USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service. USDA PLANTS Database, USDA NRCS PLANTS Database, Bugwood.org Additional Resolutions & Image Usage |
Taxonomic References:
- USDA, NRCS. 2001. The PLANTS Database, Version 3.1, National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
Invasive Listing Sources:
- Eric Ulaszek, U.S. Forest Service, Midewin National Tallgrass Prairie, Illinois
- Faith Campbell, 1998. Plants that Hog the Garden: Invasive Plants in the United States. Fine Gardening Online
- Gulf of Mexico Regional Panel, Aquatic Nuisance Species Annual Report, 2001
- Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
- John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
- Mid-Atlantic Exotic Pest Plant Council, 2005
- Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
- North Carolina Division of Parks and Recreation, Department of Environment and Natural Resources, 1998
- Virginia Department of Conservation and Recreation, 1999.
- WeedUS - Database of Plants Invading Natural Areas in the United States
- Alabama Invasive Plant Council
- Alabama Noxious Weeds Class C Noxious Weed
- Arizona Noxious Weeds
- California Invasive Plant Council
- California Noxious Weeds
- Alachua County Cogongrass Initiative
- Apalachicola Invasive Working Group Low
- Florida Exotic Pest Plant Council Category II
- Treasure Coast Cooperative Invasive Species Mgmt. Area - EARLY DRAFT
- Georgia Exotic Pest Plant Council Category 1
- South Carolina Noxious Weeds
- Tennessee Exotic Pest Plant Council Significant Threat
- Texas Noxious Weeds
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