Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.

Thallus: adnate to loosely adnate, foliose, 5-20 cm in diam., sometimes forming extensive patches, irregularly lobate lobes: subirregular, elongate, plane to subconvex, separate, 5-13 mm wide, contiguous to somewhat imbricate; apices rotund, crenate, eciliate upper surface: yellow green to pale yellow, occasionally green-gray (in shade), smooth but becoming rugose and folded with age, dull to somewhat shiny; epruinose and emaculate soredia: laminal, granular to wart-like, initially in circular soralia but becoming diffuse and confluent; isidia: absent medulla: white with continuous algal layer lower surface: black centrally, brown and naked peripherally; rhizines: dense to sparse centrally to edge of brown zone, black, simple, sometime brown or white tipped Apothecia: rare, up to 8 mm wide, laminal, sessile; disc: brown; margin: smooth but sorediate sometimes asci: clavate, 8-spored ascospores: simple, ellipsoid, hyaline, 15-24 x 8-13 µm Pycnidia: laminal, immersed conidia: weakly bifusiform, 6 x 1 µm Spot tests: upper cortex K-, C-, KC+ yellow, P-; medulla K-, C-, KC-, P+ red Secondary metabolites: upper cortex with usnic acid (major) and atranorin (trace); medulla with protocetraric acid (major) and caperatic acid (minor). Substrate and ecology: on broad leafed trees, shrubs and fence posts in open habitats, coastal to montane up to 2000m, rarely on rocks World distribution: North and South America, Europe, Asia, Africa Sonoran distribution: common on oaks, particularly in coastal California and Baja California, occasionally in central Arizona southwards into the Sierra Madre Occidental of Sonora and Chihuahua.