This alliance includes poor acidic fens, which are fed mostly by ground water, but calcium concentrations are low. However, nutrient availability is better than in ombrotrophic bogs. The vegetation is dominated by species of Sphagnum sect. Cuspidata or Polytrichum commune in the moss layer, and by short (Carex echinata and C. nigra) or tall (C. lasiocarpa and C. rostrata) sedges. Acidophilous species prevail in this kind of vegetation and some species of ombrotrophic bogs can also be present. The alliance is widely distributed on calcium-poor bedrock and includes young, managed fen grasslands, fens at fishpond and lake margins and bog laggs. It may develop through a process of autogenic succession from vegetation of the alliances Sphagno warnstorfii-Tomentypnion nitentis and Caricion canescenti-nigrae. The range of this alliance probably includes northern, western and central Europe.