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Home / Aquatic Invasives / Aquatic Plants / Water Lettuce

Water Lettuce

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Water lettuce
Water lettuce, plants - Photo by Troy Evans; Great Smoky Mountains National Park
Scientific Name: 

Pistia stratiotes L. Royle (ITIS)

Common Name: 

Water lettuce, tropical duckweed

Native To: 

Unknown, possibly South America, Africa, or the U.S. (Dray et al. 1988)

Date of U.S. Introduction: 

First described in Florida in 1765; experts disagree as to whether water lettuce is native to the U.S. (Ramey 2001)

Means of Introduction: 

Unknown (possibly native to the U.S., or it may have arrived in ballast water) (Ramey 2001)


Grows into dense mats that clog waterways (Ramey 2001)

Current U.S. Distribution: 
Southern U.S., Eastern U.S.

Distribution / Maps / Survey Status



Selected Resources

The section below contains highly relevant resources for this species, organized by source. Or, to display all related content view all resources for Water Lettuce.

European and Mediterranean Plant Protection Organization.
IUCN. Species Survival Commission. Invasive Species Specialist Group.
Ontario's Invading Species Awareness Program (Canada).
University of Georgia. Center for Invasive Species and Ecosystem Health.
East African Network for Taxonomy.
USDA. FS. Institute of Pacific Islands Forestry.

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

Federal Government
Smithsonian Institution. Smithsonian Environmental Research Center. Marine Invasions Research Lab.
DOI. USGS. Wetland and Aquatic Research Center.
Provides distribution maps and collection information (State and County).
USDA. NRCS. National Plant Data Center.
USDA. ARS. National Genetic Resources Program. GRIN-Global.
International Government
New South Wales Department of Primary Industries (Australia).
Australian Government. Department of the Environment and Energy.
State and Local Government
Pennsylvania Department of Conservation and Natural Resources.
See also: Invasive Plant Fact Sheets for plant species (trees, shrubs, vines, herbs and aquatic plants) that have impacted the state's natural lands

Wisconsin Department of Natural Resources.

Florida Fish and Wildlife Conservation Commission.
Texas A&M University. AgriLife Extension Service. Department of Wildlife and Fisheries Sciences.

University of Florida. IFAS. Center for Aquatic and Invasive Plants.