TYPE. “Habitat in variis Europae arboribus praefertim Tilia, nec non in rupibus et tectorum tegulis.” (Hoffman 1784).

Description. Life form: lichenized fungus.

[Moddified from Louwhoff 2009] Thallus foliose, 4-8(-20) cm diam., loosely to moderately attached; lobes 5-10 mm wide, radiating, contiguous but often overlapping along margins and centrally, undulating towards center; margins broadly rounded but irregularly-indented, sparsely short ciliate in axils. Upper surface mineral grey to grey, ± faintly pruinose towards apices, faintly pale maculate, isidiate. Isidia pale brown to grey-brown, laminal, scattered or densely covering central lobes, cylindrical to clavate, simple or coralloid, often crowded and forming a ± continuous crust. Lower surface black, brown towards lobe margins; rhizines continuing up to lobe margins, mostly simple. Ascomata lecanorine apothecia, rare, sessile, to 7 mm wide; disk red-brown, perforate or not; thalline rim intact or small-incised, reportedly ± densely rhizinate at or towards the point of attachment. Ascospores simple, hyaline, 9-10 × 6-9 µm., almost spherical to shortly ellipsoid. Pycnidia rare; conidia 4.5 × 1 µm, bacilliform, straight or slightly curved.

Chemistry. Cortex K+ yellow; medulla UV–, K–, KC+ red, C+ red, Pd–; atranorin, lecanoric acid.

Substrate and Habitat. Corticolous on hardwood trees and saxicolous on siliceous rocks in exposed areas.

Distribution. Cosmopolitan; in North Carolina found in Blue Ridge and Piedmont ecoregions.

Literature

Hoffmann, G.F. 1784. Enumeratio Lichenum. 102 pp (original description as Lichen tiliaceus).  

Louwhoff, S.H.J.J. (2009) Parmelina Hale (1974). Pp. 657-658 in Smith, C.W., A. Aptroot, B.J. Coppins, A. Fletcher, O.L. Gilbert, P.W. James & P.A. Wolseley (eds.). The Lichens of Great Britain and Ireland. The British Lichen Society, London.