Description: This illusive, brittle, bark epiphyte with a fragile, foliose, blue-grey thallus and delicate granular-sorediate lobe margins is relatively uncommon on nutrient-enriched trees, walls and sheltered rocks. It lacks the cilia, lip-shaped soralia and white flecks which distinguish many smaller Physcia species. Where it occurs, it is never abundant but requires warm, sheltered, enriched sites that are sun traps. The flat overlapping lobes are like stiff icing sugar. The slightest leverage with the tip of a penknife for example, will break them. Thinly scattered in Ireland.

Key Identification Features:

• Thallus rarely more than a few centimetres wide, blue-grey, fragile, of stiff, overlapping lobes
• Lobes ends with granular-soredia, delicate and easily damaged; to be handled like fine porcelain.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Physcia tribacia at iNaturalist World Species Observations database.