Scientific name Fontinalis antipyretica – Myriophyllum alterniflorum aquatic community
Common name Greater Water-moss – Alternate Water-milfoil aquatic community
Community code FW2A


FW2A map: Fontinalis antipyretica – Myriophyllum alterniflorum aquatic community

Download full pdf synopsis: FW2A



This is a species-poor, bryophyte-dominated aquatic community, usually with only sparse cover of vascular plants. Fontinalis antipyretica is the only constant species and can form extensive submerged or floating patches. The most likely other bryophytes to be seen here are Rhynchostegium riparioides, Leptodictyum riparium and Chiloscyphus polyanthos. In the more nutrient-poor acidic streams of the uplands, Fontinalis squamosa may be found. In terms of vascular plants, the trailing stems of Myriophyllum alterniflorum occasionally occur within this community, while other species are rare but may include patches of Apium nodiflorum, Ranunculus penicillatus and Potamogeton species.



This community occurs in a range of aquatic habitats including lagoons, turloughs and oligotrophic lakes but it most typically found in mesotrophic, mildly base-rich rivers and streams.



No sub-communities are currently described


Similar communities

The FW2B Rhynchostegium riparioides – Chiloscyphus polyanthos aquatic community is also dominated by bryophytes, but has a more diverse assemblage of mosses in which its titular species are far more frequent than they are in the present community.


Conservation value

This is a species-poor community of relatively low intrinsic conservation value. One exception is that Najas flexilis, a low frequency associate plants, is an EU HD Annex II species.



This community has no specific management. It may be adversely affected by eutrophication, siltation and river engineering including dredging and canalisation.