Picture taken at Collserola, following the way to Vivers Can Borni, Vallvidrera, Barcelona, Catalonia,on decideous trees, Celtis australis, with a lot of dust and nutrients.
It is a very common lichen troughout Catalonia.
Foliose lichen, thallus white or grey, more green when wet, coarsely pruinose. Lobes with soralia, isidiate at the tips that turn upwards and are more or less palmate. Rhizina simple. Medulla white. Apothecia rare with sorediate margin.
Thallus and medulla K-.
See Wirth et alter, Guía de campo de los Líquenes, m usgos y hepáticas, Editorial Omega, pag 124.
C. Perez et Alter, Guia dos Liques de Galicia, pag 312.