Description: No one could fail to be attracted by this species: foliose, rosette-like, with a blue-grey thallus, narrow, finger-like lobes and a surface covered in numerous, globose, powdery eruptions of bluish soralia. On nutrient-rich, man-made substrates, such as the tops of old concrete posts, it can look impressive. It also occurs on basic shrubs and trees, for example, elder, especially on twigs and branches. It is common throughout Ireland on suitable substrates.

Key Identification Features:

• The habitat, its rosette form, blue-grey thallus with bluish powdery soralia helps to distinguish this species
• The rarer Physcia tribacioides has a different habitat, narrower lobes and paler, small whitish soralia. Physcia dubia is always smaller and more adpressed and has distinctive lip-shaped soralia.

Original text submitted by Simon Davey

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

iNaturalist: Physcia caesia at iNaturalist World Species Observations database.