Definition of water lettuce in English:

water lettuce

noun

mass noun
  • A tropical aquatic plant of the arum family which forms a floating rosette of leaves.

    • ‘I like the gray-green leaves of water lettuce, another boatlike floater, and the tiny fronds of Azolla filiculoides, a fern that happens to float.’
    • ‘Three illegal species that top the list are the highly invasive water hyacinth, water lettuce and giant salvinia.’
    • ‘The move is aimed at trying to slow spread of harmful aquatic vegetation such as hydrilla, hyacinth, water lettuce and salvinia, alien plants that can denigrate freshwater fisheries.’