Scientific name Cladium mariscus – Phragmites australis swamp
Common name Great Fen-sedge – Common Reed swamp
Community code FW3H


FW3H: Cladium mariscus – Phragmites australis swamp   FW3H: Cladium mariscus – Phragmites australis swamp   FW3H map: Cladium mariscus – Phragmites australis swamp

Download full pdf synopsis: FW3H



This community comprises typically rather species-poor, dense stands of Cladium mariscus. Phragmites australis is also a constant species here but is usually clearly subordinate to Cladium. No other species is frequent, but careful searching between the saw-toothed leaves may occasionally reveal some plants of Equisetum fluviatile, Menyanthes trifoliata or Mentha aquatica. Infrequently, tussocks of Molinia caerulea and Schoenus nigricans may occur. There is usually very little in the way of a bryophyte layer.



These stands occur in rather nutrient-poor but strongly alkaline conditions, in a variety of habitats, including lake margins, fens and flushed areas of bog.



No sub-communities are currently described.


Similar communities

This is a distinct community which should be easily recognised.


Conservation value

Open, diverse stands of Cladium mariscus swamp and denser stands occurring adjacent to other types of alkaline fen, correspond in Ireland with the priority EU HD Annex I habitat 7210 Cladium fen*. Low diversity, closed stands occurring in isolation are not deemed to correspond.



These stands typically unmanaged.  The main threats are from peat extraction, infilling, drainage and reclamation.