Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: crustose, rarely verruculose, following contours of substrate; prothallus: absent areoles: very thin, sometimes becoming thicker and rimose in spots surface: white to pale yellow or pinkish gray, smooth and continuous, with a distinct margin, esorediate Apothecia: lecanorine, sessile, 1.2-3(-4.5) mm in diam. disc: light orange, less frequently yellowish pink, epruinose, rugose, K-, C+ red, KC-, P-, UV- margin: concolorous with thallus, usually prominent, thick, smooth, without an excipular ring of pink tissue, K- or +brown, C+ red, KC+ red, P- amphithecium: medulla thick and lax, radiate; algal layer virtually absent, or occurring as discontinuous clumps, especially in upper lateral margins; cortex +decomposed externally, variable in thickness, merging with amphithecium, radiate or not, 85-110 µm thick exciple: 60-70 µm thick, often distinct from hypothecium hymenium: (280-)310-400(-430) µm tall; hypothecium: 70-90 µm thick, with an algal layer below asci: 6- to 8-spored ascospores: rarely developed, hyaline, simple, ellipsoid, 34-52 x 20-26 µm Pycnidia: not seen Spot tests: thallus: K-, C-, KC-, P-, UV-; medulla: K-, C- (sometimes only the stipe), KC-, P- Secondary metabolites: gyrophoric, olivetoric & lecanoric (trace) acids (constant), 4-O-demethylmicrophyllinic acid (frequent accessory compound), triterpenoid substances, common in Alnus bark, can appear on TLC plates. Substrate and ecology: almost exclusively on smooth-barked, deciduous trees, such as Alnus or Acer World distribution: endemic to North American west coast, from Alaska to California Sonoran distribution: coastal southern California. Notes: Ochrolechia laevigata differs from O. subpallescens in that the latter has a thicker, more verruculose thallus and unbroken algal layer under the hymenium, while the thick margin of O. laevigata almost lacks algae.