ASCOMYCOTA LECANOROMYCETES > CALICIALES > Physciaceae

Genus Physcia, meaning 'inflated, sausage-like' - from the form of the type species

Common name:            -

Synonym:                    Physcia stellaris, form aipolia

Habitat:                         Montane (for this entry)

Substrata:                     Bark, worked timber

Growth form:                Corticolous, lignicolous

Thallus:                  Foliose

Apothecia:                    Lecanorine

BLS identity rating:        N/A

With this particular form, the thallus is typically spherical and quite compact, usually spreading to not much more than 4cm across; closely appressed, with radiating lobes that become rather indistinct in the centre of the thallus, mostly overlapping although occasionally separate; upper surface whitish pale grey, sometimes with a slightly greenish-blue tinge, indistinctly white-flecked, not pruinose, without soredia or isidia; blister-like warts or small secondary lobules sometimes at the centre of the thallus and on apothecium margins; underside whitish, pale grey or pale tan, with numerous variably coloured rhizines that often protrude beyond the lobe margins.

Apothecia usually abundant and somewhat clustered towards the centre, 1-3mm dia., discs initially flat, becoming convex, normally dark brown to black, but sometimes pruinose, exciple concolourous to the thallus.

In the Alps, this form is described as being altitudinally intermediate between Physcia biziana, and Physcia stellaris. It occurs at lower elevations, typically between the evergreen broadleaved forests up to the subalpine belt at around 1500m, where it is mainly being found on trees and wood, as in worked timber, but not rocks or stone.

In Britain, we treat Physcia aipolia and Physcia stellaris as two distinctly different species. They are very similar with both being described in the Woodland section.

The specimen featured here, that I photographed in Austria on the trunk of a wayside ash tree, is part of an interesting lichen community, growing with various other species including Lecanora chlarotera, Xanthoria parietina, Caloplaca cerina, Phaeophyscia ciliata, Physcia tenella/adscendens and Candelariella sp.