Acidic fen communities of lowland, collinar and montane areas of western and northern Central Europe, excluding the British Isles and the Iberian peninsula, extending eastward in the Baltic plain to Lithuania. Carex nigra, Carex canescens and Carex echinata are always represented, often accompanied by dispersed Carex rostrata. Rushes, Juncus filiformis, Juncus articulatus, Juncus acutiflorus, Juncus effusus, may be numerous, often marking the transition towards humid grasslands of the Molinietalia, the moss layer is formed by Sphagnum apiculatum, Sphagnum cuspidatum, Sphagnum recurvum and Polytrichum commune in the more oligotrophic, acidic sites, by brown mosses Drepanocladus fluitans, Calliergon stramineum, Calliergon cuspidatum, in more mesotrophic situations. Other characteristic species include Eriophorum angustifolium, Eriophorum vaginatum, Agrostis canina, Molinia caerulea, Pedicularis palustris, Viola palustris, Parnassia palustris, Comarum palustre, Drosera rotundifolia, Menyanthes trifoliata, Ranunculus flammula and Willemetia stipitata. Included in this unit are the extensive peatlands of Hercynian valley fens, often invaded by rushes, and with characters both of the transition mires and of the humid grasslands.