This association is dominated by Trapa natans, an annual aquatic macrophyte rooted in the bottom, but producing most biomass on the water surface. It occurs in eutrophic water bodies such as oxbows and fishponds. Its occurrence can be ephemeral, but on sites with more permanent occurrence it significantly contributes to terrestrialization. Due to its edible seeds T. natans was probably introduced by humans to various areas outside its natural range. In the Czech Republic it occurs in southern and eastern Bohemia and lowland areas of Moravia.