Description: The rarest member of the Polypodium vulgare group. It has the narrowest requirements of any of the three species of this group, being restricted to base-rich rock outcrops. It is therefore most abundant on the limestones of Cos Antrim and Fermanagh. The leaf has a characteristic broad-triangular shape, broader than any other species. The most reliable identification features are only visible under the microscope. The species is a diplod which means it has two sets of chromosomes, 74 altogether (the other species in the Polypodium vulgare complex have four or six sets of chromosomes).

All names: Polypodium cambricum L.; Polypodium australe Fee; Polypodium vulgare ssp. serrulatum F.Schultz ex Arcang.; Polypodium vulgare auct.

Distribution Map from NBN: Polypodium cambricum at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Polypodium cambricum at iNaturalist World Species Observations database.