Scientific name Carex nigra – Potentilla anserina fen
Common name Common Sedge – Silverweed fen
Community code FE3B


FE3B map: Carex nigra – Potentilla anserina fen

Download full pdf synopsis: FE3B



This wetland community is usually dominated by a mixture of Potentilla anserina, Carex nigra and Agrostis stolonifera. Ranunculus repens, Galium palustre and Mentha aquatica are also constant species but tend not to grow abundantly here. Frequently found are Hydrocotyle vulgaris, Eleocharis palustris, Phalaris arundinacea, Persicaria amphibia and Cardamine pratensis. The bryophyte layer is scant with some occasional Calliergonella cuspidata.



This wetland community occurs in mesotrophic, mildly base-rich situations, often where there is a fluctuating water table. It has predominantly been recorded from turlough basins, but is also found in dune-slacks in coastal systems as well as more typical fens and wet grasslands.



No sub-communities are currently described.


Similar communities

From the communities in this group, FE3B is distinguished mainly by the frequency of Potentilla anserina. In the rather species-poor GL2A Agrostis stolonifera – Ranunculus repens marsh-grassland, Potentilla anserina, Agrostis stolonifera and Ranunculus repens are also constants, but there Carex nigra and Mentha aquatica are only occasional. Confusion is possible with the SM6C Agrostis stolonifera – Potentilla anserina saltmarsh, but Carex nigra is seldom found there and instead halophytes such as Juncus gerardii or Glaux maritima occur.


Conservation value

This is a fairly species-rich community. This vegetation is found in turlough basins in the mid-west of Ireland where it corresponds with the priority habitat 3180 Turloughs*.  Examples from coastal dune-systems may correspond with the EU HD Annex I habitat 2190 Dune slack.



Many of these stands are subject to livestock grazing. The main threats are groundwater pollution, drainage, inappropriate grazing and reclamation.