The location of Letharia vulpina in The Teleno (León, NW of Iberian Peninsula) living as saxicolous, raised our interest in improving the knowledge of the ecological requirements of this species, as well as that of the plant community in which it lives. We have carried out a critical differential analysis about how this species behaves when it lives as saxicolous, and when it lives as epiphytic, not only in this area but also in other ones from central and northern continental Europe. We made this analysis by means of several phytosociological relevés, and notes regarding the ecological parameters having any effect on Letharia vulpina. We propose a new saxicolous association as Rhizoplaco chrysoleucae- Letharietum vulpinae.