Diverse rich fen communities dominated by small sedges, among which Carex dioica, Carex pulicaris or species of the Carex flava group, are usually prominent, but with little or no Carex davalliana. They have a distinctly western and northern distribution, occurring, in particular, in Fennoscandia, Baltic, the British Isles, the Causses, Iberia, with a disjunct area of prominence in the middle European Hercynian ranges and the Carpathians.