Lecanora horiza

It has a distinctly cracked and warted thallus above a white prothallus and glossy and convex orange or brown discs (apothecia) often aggregated into clusters.

To confirm the species, it is a good idea to section a few apothecia to check for the presence of crystals and if they dissolve in sodium hydroxide.

Lecanora campestris is similar but can be distinguished with care.

Unless identified by a recognised expert, a good photo is required, plus a note of the type of stone/substrate. A close-up of the apothecia is helpful.

On bark of deciduous trees, especially mature Ash, Sycamore and Elm. Also on rock, especially vertical calcareous gravestones and brick of churches.

All year round.

Scattered throughout southern Britain and eastern Scotland.

Status in Leicestershire and Rutland not known.