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University of Minnesota Extension

Water lettuce

Quick facts

Water lettuce is an unlisted non-native species. These species have no restrictions on sale, purchase, or possession, but they may not be introduced into a free-living state without MN DNR approval and thorough evaluation.

  • Large clones can produce dense floating mats on the water’s surface that can interfere with recreation, reduce light penetration and can create mosquito breeding habitat.

Water lettuce should be reported. See the Minnesota Department of Natural Resources recommendations for reporting invasive species.

How to identify water lettuce

  • Water lettuce (Pistia stratiotes) is a free-floating rosette of ridged leaves.


  • Thick, velvety leaves with distinct veins that radiate from the leaf base to the margins.
  • Leaves are typically two to ten inches long and form rosettes with diameters of up to about six inches.


  • Inconspicuous, tiny flowers are produced in the center of the rosette.
  • Only a few millimeters across and have a white, fuzzy hood.


  • Long, tan roots dangle from the center of the rosette.
  • Roots are highly divided with many fine segments.
Water lettuce

Angela Gupta, Extension educator; Amy Rager, Extension educator; Megan M. Weber, Extension educator

Reviewed in 2019

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