Synonymy

Juncus-Schoenus community Clapham 1940; Valley fen communities Bellamy & Rose 1961 p.p.; Cladium-Schoenus-Juncus community Haslam 1965; Schoenus edge Haslam 1965; Schoeno-Juncetum subnodulosi (Allorge 1922) Wheeler 1975,1980b p.p.; Schoenus nigricans-Juncus subnodulosus nodum Ratcliffe & Hattey 1982; Schoenetum nigricantis Dierssen 1982.

Constant species

Carex panicea, Juncus subnodulosus, Molinia caerulea, Potentilla erecta, Schoenus nigricans, Succisa pratensis, Calliergon cuspidatum, Campylium stellatum.

Rare species

Carex diandra, Dactylorhiza traunsteineri, Potamogeton coloratus.

Physiognomy

Some of the calcicolous mire vegetation in which Schoenus nigricans figures prominently is best included within the Pinguiculo-Caricetum and Carici-Saxifragetum, where Schoenus is overall only occasional and attains local dominance without a marked disruption of the floristic integrity of the communities. In the Schoenetum nigricantis, by contrast, Schoenus is a very frequent species and consistently associated with other distinctive floristic features. Although its cover is somewhat variable (it can even be absent from fragmentary stands), it is generally the dominant in this community, giving the vegetation a distinctive grey-green coloration through the year, with its semi-evergreen foliage. Very commonly, however, it occurs intermixed with at least some Juncus subnodulosus, a rush that is very rare in our submontane calcicolous mires, and sometimes this predominates, when stands have an olive-green hue in spring, turning reddish-brown with the death of the shoots in winter. Molinia caerulea is also constant and though usually not of very great abundance, it can be locally prominent, particularly in the more run-down kinds of Schoenetum. By and large, it is these plants, accompanied in some sub-communities by other rushes and sedges of medium stature (e.g. Juncus articulatus, J. acutiflorus, Carex elata, C. diandra, C. rostrata), that form the major structural element of the community, creating the general impression of a rough sward, half a metre or so in height (Wheeler 1975).

On closer inspection, however, it can be seen that it is the size and spacing of the Schoenus plants (and, to a lesser extent of the Molinia) that exert the strongest influence on the richness and organisation of the associated flora. Schoenus is a strongly gregarious, caespitose hemicryptophyte, forming loose to dense tufts of shoots on a partially-buried or emergent rootstock (Sparling 1962a, 1968).