Foto taken on the 24th February 2007 at Turó Catiu d'Or, Montseny, Barcelona, 1.660 m. altitude.
It is a cosmopolite and common lichen and it has been found in Catalonia in the low lands of Maresme or Empordà, the Pyrenees, Cerdanya, and Montseny at the upper parts (Turó del Home, Turó Catiu d'Or).
Foliose lichen, thallus grey.whitish or grey-blue. With pseudocypella difficult to see unless with wet wether. Lobes from 1 to 2 mms wide. There are no marginal bristles. Underside with dark rhizinae. Soralia light grey in colour of different forms. Saxicolous, although it can be found on bark.
Suposo que la teva experiència com a professor universitari ajuda a donar unes explicacions tant concretes i clares, molt ben estructurades i elaborades.