Xanthoria parietina forme saxicole des rochers acides de la zone xérique.
This form is characterized by its habitat: acid rocks in the xeric supralittoral zone (upper level of the orange belt, just below the white belt). Thallus thin, lobes, notably marginal, tightly appressed to the substratum. Tends toward thriving on well-lit vertical walls of neutral or weakly acid rocks where it may form very large colonies. Exposition to sun determines the overall aspect. NB. This form finds optimal conditions in the xeric zone but may also be found in other zones. Pale grey-glaucous and rosette-shaped .