20210427 09203700 1.0 TRUE Water lettuce Water lettuce is a free-floating plant aquatic weed found in tropical countries worldwide, although with no clear country of origin. Water lettuce was introduced to Australia as an aquarium and water-garden plant. It rapidly forms dense infestations that cover the surface of entire rivers, dams and irrigation channels. It affects water flow, damages native ecosystems, and impedes recreational use of water bodies. © State of Queensland (Department of Agriculture and Fisheries), 2023 weeds pests Map layer extracted from Biosecurity Queensland pest distribution survey displaying distribution of individual invasive weed species.