Ricasolia virens
Thallus to 10 cm diam., ± closely appressed, often forming rosettes; lobes 3-10 mm wide, rounded at apices, indented, wavy, occasionally with marginal folioles, often overlapping and becoming imbricate towards centre; upper surface pale grey-brown to grey-green when dry, green when wet, often smooth and shiny, more rarely becoming transversely wrinkled and ridged in older parts; lower surface pale brownish white, evenly tomentose without tomentum-free, naked patches; photobiont green algae but with scattered internal cephalodia in the medulla.
Anamorph: conidiomata pycnidia, frequent, ostiole dark brown; conidia widening at both ends, 4-5 × 1.5 μm.
Teleomorph: ascomata apothecia, frequent, disc 1-3 mm diam., pink- or orange-red with thick, inflexed thalline exciple. Ascospores 25-45 × 8-11 μm, colourless or pale brown, fusiform, 1(-3)-septate.
Chemistry: medulla C–, K+ pale yellow or K–, KC± pink, Pd–, No secondary substances identified.
Characterized by the dull grey-green colour, bright green when wet, its smooth, mostly closely appressed thallus and tendency to tolerate more shade than other members of the genus.
Host to the lichenicolous fungus Dactylospora lobariella.
Western areas of the British Isles southwards to S & SW England (Cornwall, Dorset, Hampshire - New Forest), Sussex (very rare), Ireland. Also reported from Europe, Macaronesia; more western and oceanic than other Lobaria spp. Probably absent E of the Rhône Valley.
On Quercus, Fraxinus, Ulmus and Fagus, mostly confined to ancient woodlands, occasionally on sheltered rocks in woods and on western sea-cliffs; locally common.