Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Thallus: pendulous, up to 55 cm long branching: isotomic to anisotomic dichotomic, mostly parallel basal part: concolorous to or paler than branches, often with a orange-brown pigment, conspicuously annulate branches: cylindrical to slowly tapering, distinctly segmented and annulated, slowly tapering; lateral branches: not narrowed at attachment points; apices: ±thick segments: terete and cylindrical papillae, tubercles and fibercles: absent fibrils: long (5-20 mm), distinctly curved, often numerous and arranged in a ±fishbone-like pattern soralia: puntiform, usually smaller than half of branch diameter, arising at surface of cortex from maculae or on small elevations and then slightly stipitate, convex, sometimes confluent, often immature and resembling pseudocyphellae, rarely mature and enlarged, formed mainly on lateral branches but on thicker branches too isidiomorphs: not frequent, very small on young soralia and regenerative parts pseudocyphellae: absent cortex: thick (7-12% of the radius), dull medulla: usually very thin, compact, unpigmented axis: thick and unpigmented Apothecia: not seen Spot tests: K-, C-, KC-, P+ orangish yellow Secondary metabolites: protocetraric (major) and ±lobaric (minor) acids Substrate and ecology: on bark, rarely on rock World distribution: western Europe, Macaronesia, eastern and western North America, South America, Africa, and Asia Sonoran distribution: Guadalupe Island (Baja California) and Sinaloa (Sierra Madre Occidental) Notes: Its pendulous habitus, its cylindrical branch segments, the dull and soft cortex, its conspicuously annulated basal parts that are often orange-brown, its long and curved fibrils and its production of protocetraric acid in the medulla make U. schadenbergiana a very distinctive species. In the Caribbean Islands there is a chemotype with the stictic acid aggr. (U. schadenbergiana s. str.)