Species-rich, fairly open Cladium mariscus beds of alkaline and sometimes acid fens, accompanied by cortèges of the Caricion davallianae or of the Caricion lasiocarpae. These formations are in grave decline throughout their range. Typical species: Molinia caerulea, Schoenus nigricans, Schoenus ferrugineus, Eriophorum latifolium etc. Closed stands are species-poor.