Physcia stellaris (L.) Nyl.
Lichen stellaris L., Sp. Pl.: 1144 (1753).
Thallus rosette-forming, closely attached, 2-5 cm diam., corticolous. Lobes dichotomously to irregularly branched, linear-elongate, fan-shaped, placodioid at margins, 0.8-1.2 mm wide, often densely warted and imbricate centrally. Upper surface whitish-grey to whitish-green, ± convex, often plicate-rugose centrally, matt, without soredia or maculae. Lower surface pale brown, rhizinate. Rhizines sparse, pale. Apothecia frequent, scattered or adjacent at centre of thallus, sessile, constricted at base, disc dark brownish-black often grey-pruinose, to 1.5 mm diam., margins entire or subcrenulate, concolorous with thallus. Ascospores 15-24 × 5-9 µm. Pycnidia common, immersed. Conidia 4-6 × 1 µm. Chemistry: Cortex K+ yellow; medulla K-. Atranorin, leucotylin, zeorin and two unidentified compounds.
N: S: St: In habitats similar to those for P. adscendens, mainly as an epiphyte of introduced deciduous trees in urban areas, and on native divaricating shrubs in ± open areas along riverbeds or on roadsides. It is often frequent on introduced fruit trees.
Cosmopolitan
