SUMMARYFrom 1978 to and including 1980 the author studied Dutch pastures inundated in winter and spring. The ecology and taxonomy of the following communities are described in this paper:Class:Plantaginetea majorisR. Tüxen and Preising 1950Order:Agrostietalia stoloniferaeOberdorfer, Müller and Görs 1967Alliance:Lolio‐Potentillion anserinaeTüxen 1947  Ranunculo‐Alopecuretum geniculatiTüxen 1937   Subassociations:typicumsubass.nov.     rorippetosum sylvestrissubass.nov.     equisetetosum palustrissubass.nov.  Nasturtio‐Alopecuretum geniculatiass.nov.  Triglochino‐Agrostietum stoloniferaeKonczak 1968   Subassociations:ranunculetosum repentissubass.nov.      juncetosum gerardiisubass.nov.     inopssubass.nov Agrostio‐Trifolietum fragiferiass.nov.  Subassociations:typicumsubass.nov.     festucetosum rubraesubass.nov.     inopssubass.nov. Derivate community ofFestuca arundinacea‐[Lolio‐Potentillion] Basal community ofAgrostis stolonifera‐[Lolio‐Potentillion] Community ofScirpus maritimusandAlopecurus geniculatusClass:Asteretea tripoliiWesthoff and Beeftink 1962Order:Glauco‐PuccinellietaliaBeeftink and Westhoff 1962Alliance:Armerion maritimaeBraun‐Blanquet and De Leeuw 1936  Ononido‐Caricetum distantisRunge 1966  Juncetum maritimiBilik 1956Besides some comments are made on theAlopecurus arundinaceuscommunity, observed in Sweden, which is unclear syntaxonomically. The relation of these communities to one another and to the two major environmental factors – s