Xanthoria parietina forme saxicole des rochers acides de la zone xérique.
This form differs from the type in that it occurs on the acid rocks of the xeric supralittoral zone at the upper level of the "orange belt" and just below the "white belt". The thallus is slender and the lobes, in particular the marginal ones, are strongly applied to the rocks but their extremities are straightened. It seems to prefer the sunny vertical faces of siliceous, acidic or not too acidic rocks, where it can form large colonies. Exposition to sun determines the overall aspect.
N.B. This form finds optimal conditions especially in the xeric zone but can also be found in other zones.
N.B. The rosette shaped and the "cockade" coloration, pale gray-glaucous in the center and yellow at the margins, is quite characteristic.