ASCOMYCOTA | LECANOROMYCETES > LECANORALES > Parmeliaceae

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

Common name:            Hammered Shield Lichen

Synonym:                    -        

Habitat:                         Ubiquitous

Substrata:                     Bark, wood and rock

Growth form:                Corticolous, lignicolous and saxicolous

Thallus:                  Foliose

Apothecia:                    Lecanorine, scarce

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

Highly variable; thallus forming rosettes from 5-12cm wide or randomly intricate patches of more loosely attached lobes that may extend to 20cm or so; upper surface pale silvery-grey, bluish-grey or greenish-grey when dry, sometimes partly white-pruinose, generally more greenish when moist; lobes to 5mm broad, flat to weakly pitted with a 'hammered' appearance, overlapping especially at the centre of the thallus, apieces truncated and incised, conspicuously embossed with scattered oval or elongate white pseudocyphellae that frequently fuse to form a coarse incomplete network, along which soralia develop; lobes often with pale brownish tips; lower surface dark brown towards the margin, otherwise black, with simple or forked rhizines.

Apothecia only occasionally present, scarce and scattered, disc red-brown to dark brown, with partially sorediate thalline margin.

Very similar to Parmelia saxatilis, except that species is covered with isidia, not soralia.

Common throughout Britain, from coastal to montane habitats, occurring primarily on trees, but also on weathered timber and firm siliceous rock.