Dwarf oligo-mesotrophic annual communities of recently emerged muds and sands of the nemoral, boreonemoral and boreal regions. Terrestrial forms of amphibious species and annual species are frequent. A dynamic habitat, and several aspects can occur during the vegetation cycle. If the substrate is sufficiently wet, and also in advanced successional stages, the moss layer is abundant. Typical species are Juncus bufonius, Cyperus fuscus, Cyperus flavescens and other species from vegetation of class Isoeto-Nanojuncetea.