Order: Teloschistales       Family: Teloschistaceae Species: Flavoplaca citrina (Caloplaca citrina) aggregate Growth type crustose. K+ crimson / purple. Very common on walls, mortar and calcareous rocks, also sometimes found on bark, moss and soil. Recent work has shown that 'true' Caloplaca citrina does not occur in Britain and Ireland, the name having been wrongly applied to what is now known to be a complex of species: Caloplaca austrocitrina, Caloplaca dichroa, Caloplaca arcis, Caloplaca limonia and Caloplaca flavocitrina

Microscope photograph

Caloplaca citrina. March 2012