Teloschistaceae Flavoplaca flavocitrina (Caloplaca flavocitrina) Growth type crustose Chemical results: K+ crimson Common on cement, mortar, calcareous rocks and asbestos and also found on basic-barked trees. Thallus of contiguous or dispersed greenish-yellow areoles or small squamules, the margins splitting and forming soralia that can eventually cover the thallus. Soredia lemon-yellow and paler than thallus. Apothecia infrequent, slightly darker yellow than thallus. Micrograph below. One of the species in the Flavoplaca citrina aggregate.

Microscope photograph

Caloplaca flavocitrina
Steeple and Lytchett Minster, Dorset. February 2014, December 2016