Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Life Habit: lichenized Thallus: fruticose, caespitose to pendent or rarely somewhat prostrate branches: terete, occasionally compressed (particularly at nodes along the segments), primarily isotomically dichotomous but sometimes anisotomically dichotomous, lateral branchlets rare surface: white to gray, gray-black, tan, brown or black, sometimes mottled, generally smooth, pseudocyphellae plane and closed or more often perforate and opening into a hollow thallus center; soredia: present or absent; isidia absent cortex: prosoplectenchymatous medulla: composed of rather compact to loose arachnoid to distinctly granular hyphae; often with gaps associated with the pseudocyphellae , and commonly hollow centrally with a thick or thin medullary layer adjacent to the cortex photobiont: primary one a trebouxioid alga, secondary photobiont absent Ascomata: apothecial, usually frequent, formed laterally but sometimes appearing terminal due to recurved branch ends, up to 5 mm diam., circular; margin: thalline, persistent, smooth to crenulate or weakly spinulose, concolorous with thallus; disc: concave initially, becoming flat or convex with age, usually black or dark brown; epihymenium: red-brown to dark brown; hymenium: hyaline, 120-240 µm thick; hypothecium: hyaline or pale, over an algal layer; paraphyses: sparsely branched and anastomosing asci: clavate, thick walled, Lecanora-type, I+ blue; tholus I+ blue; usually one-spored ascospores: brown, muriform, ellipsoid, with or without an epispore (2-4 µm thick), 70-160 x 23-52 µm Pycnidia: infrequent, immersed or partially emergent, often dark above conidia: weakly or unequally bifusiform, mostly 4-7 x 0.5-1 µm Secondary metabolites: medulla often with some combination of orcinol and ß-orcinol depsides, ß-orcinol depsidones, benzyl esters, aliphatic acids, anthraquinones and /or unknowns Geography: neotropics and southern and eastern Asia Substrate: on bark, wood, soil, or detritus. Notes: When sterile, members of this genus are most likely to be confused with Bryoria, which is much more common in mountainous areas of the Sonoran region. Most species of Oropogon, including the two known to occur in our region, can be distinguished from Bryoria by the distinctly perforate pseudocyphellae. These are occasionally sparse, however, especially in poorly developed or scrappy material.