A crustose species with a yellow-grey, thin to thick, cracked and somewhat warted, thallus that is surrounded by a black prothallus. The apothecia tend to be numerous, and sessile, with a thick margin that may be pruinose. The black discs are flat, but may become slightly convex.
Thallus: C-, K+ yellow, UV-
In Scotland, Buellia disciformis is widespread in upland areas where it occurs on smooth bark. BLS distribution map
scottishlichens.co.uk 