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Water Lettuce

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.

Water lettuce
Image use policy

Water lettuce, plants


Photo by Troy Evans; Great Smoky Mountains National Park

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Distribution / Maps / Survey Status


Selected Resources

The section below contains highly relevant resources for this species, organized by source.

Federal Government
International Government
State and Local Government