ASCOMYCOTA | LECANOROMYCETES > CALICIALES > Physciaceae

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

Common name:            Hoary Rosette Lichen

Synonym:                    -

Habitat:                         Woodland, wayside trees, fences

Substrata:                     Bark, worked timber; rarely rock and old walls

Growth form:                Corticolous, lignicolous (saxicolous)

Thallus:                  Foliose

Apothecia:                    Lecanorine

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

Thallus typically spherical or loosely rosette-shaped, to around 6cm across, sometimes spreading to nearer 10cm; closely appressed with 1-2mm wide radiating lobes that are usually slightly overlapping; upper surface whitish to pale grey, often with a bluish tinge more noticeable when dry, usually distinctly white-flecked, but sometimes difficult to see, becoming more evident when moist, only rarely weakly 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 pale to dark coloured rhizines that often protrude beyond the lobe margins.

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

Common and widespread; occurring primarily on well-lit, nutrient-rich fences and similar worked timber structures as well as on the bark of tree trunks, branches and the rough nodes of twigs, and shrubs; sometimes, although rarely, on coastal rock and old walls.

Physcia aipolia is very similar in appearance to Physcia stellaris (separately described), but usually slightly bigger and less compact, with a pale bluish tinge. In practice, these features are hard to determine in the field.