Parmeliaceae Parmelina tiliacea Growth type foliose Chemical results: Cortex K+ yellow. Medulla K-, C+ carmine-red, KC+ red, P-, UV- Occurs on nutrient-rich trees, also on siliceous rocks and roofing tiles The pale blue-grey thallus is smooth and sometimes slightly pruinose, the rounded lobes +/- notched and indented at the tips. Upper surface covered with brown or greyish-brown isidia that spread from the centre, isidia cylindrical or coralloid and unstalked. Lower surface pale brown at the edges, black in the centre and has simple rhizines. Apothecia very rare Similar: Parmelina pastillifera; same chemistry, blue-black isidia

Parmelina tiliacea
Badbury Rings and Chettle woods, Dorset. January 2017, December 2018