ASCOMYCOTA | LECANOROMYCETES > OSTROPALES > Graphidaceae

Genus Phaeographis, meaning 'grey-brown writing' from the shape and colour of the apothecia

Common name:            -

Synonym:                    -

Habitat:                         Woodland

Substrata:                     Smooth bark

Growth form:                Corticolous

Thallus:                  Crustose

Apothecia:                    Lirellate

BLS identity rating:        Graded 3/5 (microscopic examination recommended to be sure)

Thallus thin, smooth and glossy, typically 2-4cm across, powdery, slightly granular or cracked-areolate; rather variable, but usually light grey to creamy white, sometimes with a yellowish or greenish tinge.

Lirellae numerous and scattered across the thallus, very immersed, elongate, straight, curved or scimitar-shaped, often bunched, joined and star-shaped, ends pointed; usually wide open with a prominent dark carbonaceous margin and exposed grey-brown pruinose disc.

Phaeographis dendritica is fairly common on smooth patches of acid-barked shaded trees, mainly in the south and southwest.

The first two close up photos featured below that were taken on a wayside tree at Moors Valley Country Park are considered very likely, but the last one is rather moist and glistening so there was some debate when checked whether it could be Graphis scripta. I've left it here for reference, but in either case none of these can be confirmed without spot-testing and closer inspection.