Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: foliose to subfruticose, forming small to medium-sized rosettes up to 3 cm wide or extensive colonies, loosely adnate, lobate lobes: dorsiventral, flattened to concave or irregular, 0.4-1 mm wide; tips: rotund, 0.1-0.4 mm wide upper surface: yellow to orange, smooth to shiny, often wrinkled, sorediate soredia: granular, blastidious, in marginal to submarginal soralia or at lobe tips medulla: white, reticulate, with short hyphae lower surface: white, smooth to somewhat wrinkled, often with white rhizines Apothecia: very rare, laminal, stipitate, up to 3.5 mm in diam.; margin: smooth but often sorediate; disc: orange; epihymenium: brown, c. 10 µm thick hymenium: hyaline below, 70-90 µm tall; paraphyses: simple or rarely branched, cylindrical, septate; hypothecium: hyaline to pale brown, 25-40 µm thick asci: clavate, 8-spored ascospores: ellipsoid, polarilocular, hyaline, 16-17 x 7-9 µm; septum: 6-7 µm wide Pycnidia: common, immersed to protruding, darker than upper surface conidia: variable within the pycnidium, 3-4 x 1-1.5 µm Spot tests: upper surface K+ purple, C-, KC-, P- Secondary metabolites: parietin (major), fallacinal, emodin, teloschistin and parietinic acid. Habitat and ecology: on bark, rarely on detritus, rock, or soil, often in humid microclimates World distribution: western North America Sonoran distribution: coastal regions of southern California. Notes: Xanthomendoza oregana somewhat resembles X. ulophyllodes, but its lobes are more irregular, wrinkled and slightly narrower. Soralia are not as frequent in X. ulophyllodes, and never becomes laminal in X. oregana. When pycnidia are present, the conidia contained in them is a mixture of ellipsoid and bacilliform shapes (Lindblom 1997), a character that separates X. oregana from all other taxa in Xanthoria and Xanthomendoza. Compared to Xanthoria candelaria, X. oregana has broader lobes, which are more adnate, as well as different rhizines and conidia. See also notes for X. fulva for comparison with that taxon