Description: This lichen of damp, siliceous, upland rocks and fast-flowing acid streams is a conspicuous, grey or pinkish-brown crustose species with closely attached, radiating margins giving the thallus a rosette-like appearance. In rather lively, wet situations alongside rivers it is found only with soralia which are greenish-brown, most often seen as large fleck-like scars on the surface of the lobes. In drier sites, it may have brown, scab-like structures (cephalodia) which tend to lie at the centre of the thallus. The pink or yellowish discs (0.8-1.6mm) are occasional. It is a lichen of the transitional or damp zone of a river. Throughout Ireland. All previous records of P. gelida are believed to belong here.

Key Identification Features:

• A grey-brown crustose lichen with radiating lobes pocked with ulcer-like soralia; damp or wet places on upland siliceous rocks
• At drier sites, the thallus may have brown, scab-like cephalodia and thick-rimmed, pinkish discs.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Placopsis lambii at iNaturalist World Species Observations database.