Herteliana gagei forme saxicole des rivages exposés

      This form, which testifies to the ancient presence of an oceanic forest, differs from the type of Herteliana gagei by its habitat in the shade at the base of the rocks in the aerohaline heathlands of the very exposed Caps and Points. The thallus, not fertile, is covered in places with small pustular gray-greenish, yellowish-green soredia. This form, which is probably a form of "suffering" or "resistance" to very harsh climatic conditions, makes the transition with the very sorediated form of the oceanic forests of Cape Lizard and English Cornwall but present in Finistère: Herteliana gagei forme sorédiée.