A crustose lichen with a thin, grey to black thallus that is often not visible. The abundant and often crowded apothecia are yellow-orange to orange with a glossy margin that becomes excluded. The disc is convex.
Thallus: K-. Apothecia: K+ purple
Though more common in the east than in the west, Caloplaca holocarpa can be found throughout Scotland on well-lit, nutrient-enriched, calcareous stones, including mortared church walls, where it is often an early coloniser. BLS distribution map
On mortared church walls, Caloplaca holocarpa is often found alongside Lecanora albescens and Lecanora dispersa.
scottishlichens.co.uk 