Synonymy

Asplenium trichomanes-Fissidens cristatus Association, Limestone facies p.p. and Montane facies Birks 1973.

Constant species

Asplenium ruta-muraria, Asplenium trichomanes, Asplenium viride, Cystopteris fragilis, Festuca ovina, Ctenidium molluscum, Fissidens cristatus, Tortella tortuosa.

Rare species

Polystichum lonchitis, Woodsia alpina.

Physiognomy

The Asplenio-Cystopteridetum comprises open vegetation, often fragmentarily disposed in rock crevices on narrow ledges and among screes, in which a variety of ferns can assume prominence. Asplenium trichomanes (sometimes, according to Page (1982), ssp. trichomanes here, rather than the more widespread ssp. quadrivalens) remains quite common in this community but it peters out at higher altitudes. Even more so is this true of A. ruta-muraria, which among available samples is constant, but across the range of this vegetation as a whole is largely confined to stands outside the Scottish Highlands. The most characteristic spleenwort, then, is A. viride, particularly in the mountains of Scotland and northern England. This fern can occur in considerable abundance here, its rosettes of rather delicate pale green fronds, typically all turned towards the light, persisting into the winter and then dying down (Page 1982).

The other distinctive constant among the ferns is Cystopteris fragilis, a gregarious species, the fragile little fronds of which emerge rapidly in spring but which are cut back suddenly by the first frosts of autumn (Page 1988).