Scientific name Carex nigra – Ranunculus flammula fen
Common name Common Sedge – Lesser Spearwort fen
Community code FE3A


FE3A: Carex nigra – Ranunculus flammula fen   FE3A: Carex nigra – Ranunculus flammula fen  FE3A map: Carex nigra – Ranunculus flammula fen

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This is fairly low-growing vegetation type in which small sedges are prominent, but not necessarily dominant. The constant species are Carex nigra, Ranunculus flammula, Hydrocotyle vulgaris, Mentha aquatica, Carex panicea and Agrostis stolonifera, but they each have a wide range of potential abundances, making this community quite variable.  Juncus articulatus is frequent and lends some structural diversity to the assemblage. Also often present are Galium palustre, Carex viridula and Leontodon autumnalis. The most frequent moss is Calliergonella cuspidata, but in more base-rich situations one may also detect some of the ‘brown mosses’ indicative of alkaline fens, usually Campylium stellatum or Drepanocladus cossonii/revolvens.



This wetland community occurs in nutrient-poor, fairly neutral situations, often where there is a fluctuating water table. Hence, it is found in dune-slacks in coastal systems and in turlough basins, as well as more typical fens, flushes and wet grasslands.



No sub-communities are currently described.


Similar communities

The FE3B Carex nigra – Potentilla anserina fen shares several constant species with the present community, however in FE3B Potentilla anserina is distinctly more abundant. Eleocharis palustris is more abundant in the Eleocharis palustris – Agrostis stolonifera fen than in FE3A and Carex nigra is less characteristic. In the FE3D Carex nigra – Calliergonella cuspidata fen, there is usually a plentiful layer of Calliergonella and, other than Carex nigra, carices are much scarcer.  Two grassland communities are also similar. The GL1B Agrostis stolonifera – Filipendula ulmaria marsh-grassland differs in that Filipendula ulmaria is a constant there but seldom seen in FE3A, while in the rather species-poor GL2A Agrostis stolonifera – Ranunculus repens marsh-grassland, Carex nigra is only occasional.


Conservation value

This is a fairly species-rich community. Examples from coastal dune-systems may correspond with the EU HD Annex I habitat 2190 Dune slack. This vegetation is also found in turlough basins in the mid-west of Ireland where it corresponds with the priority habitat 3180 Turloughs*.  Stands of the community from further east in the country may represent habitat 7230 Alkaline fens if they support ‘brown mosses’.



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