Physconia grisea subsp. grisea forme thermophile Atlantique.
This form is distinguished from the type by its purplish-grey, lilac-grey in dry weather and glaucous-grey slightly lilacin in wet weather. Isidia-like soralia may cover the center of the thallus and rarely take on the appearance of large greyish granules. On isolated deciduous trees (Tilia, etc.) or city parks, in particular on the Atlantic islands or on the coasts.
N.B. Not to be confused with Physconia grisea subsp. lilacina mountain species without soralia.