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Invasive Species: Water Lettuce

Invasive Species: Water Lettuce

Water Lettuce

(Pistia stratiotes)
*Detected in Michigan*

WATCH LIST

This species is currently allowable for sale and possession in Michigan. If these plants are observed outside of cultivation, please report to:

EGLE Aquatic Invasive Species Program EGLE-WRD-AIP@Michigan.gov.

If possible, please take one or more photos of the invasive species you are reporting. Also make note of the location, date and time of the observation. This will aid in verification of your report. You may be asked to provide your name and contact information if follow-up is needed.

- Or - use the Midwest Invasive Species Information Network (MISIN) online reporting tool

- Or - download the MISIN smartphone app and report from your phone - MISIN.MSU.edu/tools/apps/#home

Identification:

  • Free-floating – forms a rosette of leaves that resembles an open head of lettuce.
  • Leaves are thick, ridged, rounded at the end, light green, and have short, white hairs.
  • Produces small, white to pale green flowers.
  • Many feathery roots dangle under the rosette.

water lettuce
Photo courtesy of Troy Evans, Great Smoky Mountains National Park, Bugwood.org.

water lettuce
Photo courtesy of Karen Brown, University of Florida, Bugwood.org.

water lettuce invasion
Photo courtesy of USDA APHIS PPQ, Oxford, North Carolina, Bugwood.org.

Habitat: Water lettuce can be found in ponds, lakes, rivers and streams.

Native Range: Uncertain – likely tropical or subtropical.

U.S. Distribution: Water lettuce has been introduced to the south and western United States, as well as Ohio, New York, New Jersey, Maryland, Delaware and Michigan.

Local Concern: This freshwater perennial creates thick mats that reduce oxygen levels, block sunlight and prevent growth of submerged vegetation. Mats interfere with recreation and can have a negative effect on fish and other aquatic species in an infested area.

MORE INFORMATION:

Water Lettuce Invasive Species Alert - Printable PDF

Status and Strategy for Water Lettuce (Pistia stratiotes L.) Management - Printable PDF