This vegetation type is dominated by the tiny wetland fern Pilularia globulifera, which forms dense low-growing stands in shallow oligotrophic to mesotrophic water bodies with fluctuating water table. It was recorded in two fishponds in the Třeboň Basin in the 1930s, but disappeared soon afterwards. A new locality was found in the year 2007 in the Karhov fishpond near Studená in the Jihlavské vrchy Mountains.