LICHALP

Placynthium posterulum (Nyl.) Henssen

Syn.: Pterygium posterulum Nyl.

Lichenised.

Substrate: calciferous rocks

Altitudinal range: from the montane belt (potential vegetation: deciduous forests dominated by Fagus sylvatica and closed coniferous forests with Picea abies) to the alpine belt (potential vegetation: treeless Alpine grasslands and tundras, to the lower limit of perennial snow and the equilibrium line of glaciers)

Note: a species recalling a poorly developed P. subradiatum, with which it might have been confused, the olive-brown to blackish brown thalli forming rings with disintegrating centres, but radial growth often less prominent, marginal lobes more or less round in transverse section and lower surface lacking any blue to violet pigment, loosely attached to the substrate by bundles of rhizohyphae; on sunny, steep faces of calcareous rocks; widespread in Central Europe, with a few scattered records from Eastern Alps.