Parmeliaceae Parmelina pastillifera Growth type foliose Chemical results: Cortex K+ yellow. Medulla K-, C+ carmine-red, KC+ red, P-, UV- Found on well-lit, roadside trees with nutrient-enriched bark, also on wood, siliceous rocks, roof tiles and memorials. Light blue-grey thallus, the scattered blue-black isidia stalked and knob-like with flattened tops. Lobes are adpressed, often pruinose near tips, the lower surface black in the centre but brown at the margins and has simple rhizines. Apothecia and pycnidia are absent. Similar: Parmelina tiliacea has brown-tipped isidia

Parmelina pastillifera
Badbury Rings and Pamphill Green, Dorset. August 2012 and January 2016