Lecanora polytropa Granite-speck Rim-lichen

Lecanora polytropa is a rather uniformly coloured pale yellow to greenish-yellow crustose lichen, with small convex apothecia, the paler margin becoming excluded. The thallus is areolate yellowish-green with a black prothallus. It is widespread across Britain wherever siliceous rocks, walls and worked timber is found. The thallus is K+ weak yellow, C-, KC+ yellow, P- and UV-. Records within the recording area are focussed around quartz-conglomerate outcrops and boulders of Old Red Sandstone in western Gower. This western bias probably reflects recording effort and it is likely to be more widespread in upland areas further north and east than the distribution map suggests.

Listed by Alan Orange in Flora of Glamorgan (Wade et al, 1994).