Description: This is a species of basic-barked wayside and parkland trees, and of vertical, sheltered rocks and boulders. In its early stages of development the pale grey thallus is not unlike that of other species in the genus. Well-grown specimens however, are less difficult to identify as it becomes densely grey-isidiate at its centre. On rocks in County Kerry for example, these stick-like isidia may become grossly exaggerated in size which has caused it to be mistaken for the very rare Heterodermia speciosa, which has never been recorded from Ireland. In Ireland, the species is rather widely scattered.

Key Identification Features:

• Forms grey foliose rosettes densely isidiate towards the centre
• On the basic or slightly nutrient-rich bark of sycamore, ash and elm or damp boulders.

Original text submitted by Vince J. Giavarini

Distribution Map from NBN: Physcia clementei at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Physcia clementei at iNaturalist World Species Observations database.