This association is formed of species-poor to monospecific stands of Lemna trisulca, a submerged plant freely floating below the water surface. It occurs in mesotrophic to eutrophic still water bodies, especially in oxbows and alluvial pools with clear water. It avoids water bodies with deep layers of organic silt on the bottom. In the Czech Republic it occurs mainly in lowlands and colline areas, with a remarkable concentration of localities in the river floodplains.