Description: Lichen. Thallus foliose, appressed, moderately to loosely adnate, to 5 cm diam. Lobes to 4 mm wide, irregularly shaped, rounded to slightly elongate, flat to somewhat convex, margins often swollen and eroded. Upper surface olive-brown, with marginal to submarginal, elongated to irregular pseudocyphellae; without isidia and soredia. Lower surface usually dark brown, with sparse, concolorous rhizines. Apothecia usually abundant, crowded in the centre but frequently extending to the lobe ends, margins smooth or slightly crenulate, pseudocyphellate, to 5 mm diam. Spores 8- 13 x 5- 9 μm. Pycnidia common. Conidia slightly dumbbell-shaped or bacilliform, 5- 7 x 1 μm.

Photobiont: Data lacking.

Chemistry: Cortex C-, K-, KC-, PD-. Medulla C-, K-, rarely K+ yellow, KC-, PD+ orange, rarely PD-; fumarprotocetraric acid, rarely no secondary substances (by TLC).

Ecology: Epiphytic on deciduous trees, especially Salix and Alnus incana along water courses, but also in other habitats.

Distribution type: Widely distributed in the Nordic countries, particularly common in the Betula woodlands in Iceland and northern Fennoscandia. Less frequent towards the south and absent in southernmost Scandinavia. Circumpolar, primarily boreal, but extends to the low arctic and temperate zones. Isolated occurrences in the Alps and other mountains.

Taxonomy: Data lacking.

Note:

Distribution Database: Distributions

Distribution Database: Discover Life

Picture Database: Tropical Lichens

Molecular Database: Genbank

Synonym Database: Index Fungorum

Synonym Database: Mycobank