Order: Teloschistales Family: Teloschistaceae
Species: Caloplaca citrina sens. str.
Photos: On Olearia branch. Allihies, Co. Cork, SW Ireland.
Identified by John Douglass
Very variable. Yellow to greenish-yellow or orange thallus comprised of minute, sometimes lobed, granules +/- entirely covered with orange soredia. Yellowish-orange apothecia with sorediate paler margins. Spores 10.5-15 x (4-)5-7.5(-8) Ám, septum 3-5 Ám. The asci are often long and narrow. Microscope photograph below.
Thallus and apothecia K+ crimson / purple.
Very common on walls, mortar and calcareous rocks, also sometimes found on bark, moss and soil.
Similar: Caloplaca flavocitrina