Synonymy

Oxyphilous fen vegetation Pallis 1911, Godwin & Turner 1933, Tansley 1939p.p.; Carex rostrata-Acrocladium cor difolium I cuspidatum sociation Spence 1964 p.p.; Carex lasiocarpa-Myrica & Myrica-Carex lasiocarpa sociations Spence 1964 p.p.; Carex nigra-Acrocladium sociation Spence 1964 p.p.; Carex rostrata-Aulacomnium palustre Association Birks 1973; Poor fen communities Proctor 1974 p.p.; General fen Adam et al. 1975 p.p.; Carex curta-Carex rostrata community Wheeler 1978; Caricetum lasiocarpae Koch 1926 sensu Birse 1980 p.p.

Constant species

Carex nigra, C. rostrata, Eriophorum angustifolium, Potentilla palustris, Succisa pratensis, Aulacomnium palustre, Sphagnum squarrosum.

Physiognomy

The Carex rostrata-Sphagnum squarrosum mire is a fairly heterogenous vegetation type characterised overall by the dominance of sedges with scattered poor-fen herbs over a patchy carpet of moderately base-tolerant Sphagna. The sedge cover is usually a few decimetres tall but quite variable in its abundance. The commonest species throughout are Carex rostrata and C. nigra, the former generally the more extensive and sometimes with a dense cover, the latter typically less abundant, though locally dominant, as in some stands of the Carex nigra-Acrocladium sociation described from Scottish lochs by Spence (1964) and in some of the Malham Tarn fens in North Yorkshire (Proctor 1974). C. lasiocarpa extends its occurrence among British mires into this kind of vegetation and it too can attain local prominence, so much so that stands which, on general grounds, clearly belong here have sometimes been included in distinct communities characterised by this sedge: e.g. the Carex lasiocarpa sociations of Spence (1964) and the Caricetum lasiocarpae (Koch 1926) of Birse (1980). C. curta, though generally more characteristic of oligotrophic and base-poor Rhynchosporion pools, is occasionally found (Spence 1964, Birks 1973, Wheeler 1978 who diagnosed a Carex curta-Carex rostrata community from the Ant valley in Norfolk) but C. limosa is typically absent. Likewise, towards the other extreme, C. diandra does not penetrate into this community: it is a good diagnostic species for the closely-related Carex rostrata-Calliergon mire. Finally, there may be a little C. echinata, especially where the Car ex-Sphagnum squarrosum mire extends on to firmer flushed peats.