ASCOMYCOTA | LECANOROMYCETES > LECANORALES > Parmeliaceae

Genus Parmelia, meaning 'embedded fruit bowl' - from the shape of the apothecia

Common name:            Peppered Shield Lichen

Synonym:                    -        

Habitat:                         Ubiquitous

Substrata:                     Bark and rock

Growth form:                Corticolous and saxicolous

Thallus:                  Foliose

Apothecia:                    Lecanorine, infrequent

BLS identity rating:        Graded 1/5 (identification should be straightforward)

Highly variable; foliose thallus forming complete or partial rosettes, typically 3-6cm across, but occasionally reaching as much as 20cm; comprised of loosely attached short lobes, to 3mm wide, slightly broadened and truncate at the apices; separate, contiguous or overlapping.

Upper surface bluish-grey to greenish-grey in shade, usually tinged pale yellowish-brown towards the lobe ends; covered with oval to elongate, slightly raised, scattered pseudocyphellae, which sometimes fuse to form an embossed course network of white lines and dots across the surface; isidia with grey-brown tips form, at first arising from the white reticulations, later from the rest of the upper cortex, initially rather sparce, but can become numerous and obscuring the thallus; underside black, lighter at the margins, covered with dense, simple or occasionally branched, black rhizines that extend to the edge and can often be seen protruding.

Apothecia infrequent, but where present, large to 10mm dia., disc red-brown to dark-brown with thin, isidiate or crenulate margins.

Parmelia saxitilis is mainly found on acid-barked trees, shrubs and Calluna stems, also on rocks, walls, roofing tiles, memorials etc. It is widespread and common, and often abundant, occurring in various habitats from the coast to mountains.

Frequently parasitised by the coral-red fungus, Marchandiomyces corallinus.