Description: A very common fern of mortared stone and brick walls or of limestone or basalt rock outcrops. (Far commoner than the ssp. trichomanes, which is virtually absent from Northern Ireland except for one known site in the Mournes.)

All names: Asplenium trichomanes ssp. quadrivalens D.E.Mayer; Asplenium trichomanes ssp. quadrivalesns D.E.Meyer emend.Lovis

Distribution Map from NBN: Asplenium trichomanes ssp. quadrivalens at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Asplenium trichomanes ssp. quadrivalens at iNaturalist World Species Observations database.