Description: Currently known only from Counties Cork (west), Wicklow, Tyrone and Antrim, C. salicinum is a ‘pin lichen’ species, with brown pruina (frosting) coating the undersurface of the head. In this respect it most strongly resembles C. viride, but that species has a K-, bright green thallus. The thallus of C. salicinum is largely immersed and so shows as a faint stain. In spite of this, it tests K+ yellow to red. Spores commonly < 10µm long; it grows on dry acid bark.

Key Identification Features:

• ‘Pin-lichen’ with underside of head, brown, thallus a stain, never green
• Thallus K+ yellow-red.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Calicium salicinum at iNaturalist World Species Observations database.