Synonymy

Mixed fen Holdgate 1955b p.p.; Carex nigra-Sanguisorba officinalis nodum Proctor 1974 p.p.; Carex nigra-Sanguisorba officinalis community Wheeler 1980c; Crepido-Juncetum Jones 1984.

Constant species Carex nigra, C. panicea, Crépis paludosa, Equisetum palustre, Filipendula ulmaria, Molinia caerulea, Potentilla erecta, Ranunculus acris, Succisa pratensis, Valeriana dioica, Calliergon cuspidatum.

Rare species

Primula farinosa.

Physiognomy

The Molinia caerulea-Crepis paludosa mire is a striking vegetation type, well-defined by a substantial block of constants and frequent companions, but showing quite considerable variation in its associated flora and embracing stands which, at one extreme, resemble swamp and, towards the other, are of a rank grassy character. Molinia caerulea is almost always present and it is often abundant, being the commonest dominant overall and frequently growing in a strongly-tussocky form, creating an irregular canopy up to 50 cm or so tall, and exerting a marked influence on the character and distribution of the associates. Among these are some other plants which can make a substantial contribution to the herbage. Carex nigra, for example, is a constant and it quite frequently occurs as prominent tufts or tussocks (var. subcaespitosa), sometimes rivalling or exceeding Molinia in its cover, particularly in the Sanguisorba sub-community (Proctor 1974). C. panicea can also be fairly abundant and C. pulicaris occurs commonly, too, though not usually as dense tufts. Then, in stands which are transitional to swamp, there can be some C. appropinquata, as at Malham Tarn in North Yorkshire (Proctor 1974), or C. rostrata, as at Sunbiggin Tarn in Cumbria (Holdgate 19556). In the Festuca subcommunity, by contrast, it is taller rushes and grasses which, together with Molinia, provide the bulk of the cover, Juncus acutiflorus forming locally dense patches, J. conglomeratus occurring as scattered tussocks. J. articulatus is also occasional throughout, though it often grows as a semi-decumbent plant and is rarely abundant.

The other important structural element typical of the community as a whole comprises hemicryptophyte dicotyledons which are capable of moderate to tall growth among the Molinia, sedges and rushes, but many of which can also subsist as rosettes in grazed stands. Most frequent among this group are Succisapratensis, Filipendula ulmaria, Valeriana dioica, Cirsium palustre, Caltha palustris and, adding a particularly distinct regional look, the Continental Northern Crépis paludosa and Northern Montane Trollius europaeus.