Lich. Univ.: 619 (1810) but in IF page 610.
Type: [Poland] Silesia, Mosig (H-ACH 1890 - lectotype).
Thallus: short and erect to long and pendent, to 30 cm long, usually coarse and stiff; ramifications sympodial or isotomic-dichotomic, with divergent to parallel branches. Base not blackened, often with a brownish-orange pigment. Main branches cylindrical to irregular, secondary branches not narrowed at their point of attachment to the main stems. Segments cylindrical to ? sausage-like, terete to ? angular, usually without foveoles or transverse furrows. Papillae low and inapparent to verrucose, sparse; tuberucles conspicuously raised, at first eroded and white at tip, then bursting to form ulcerose soralia, sparse to numerous; fibercules absent; fibrils spinulous, to 2-5 mm long, few to numerous. Soralia punctiform to larger than half the branch diameter, stipitate, ?at to convex or frequently capitate, arising mainly on tuberucles, nearly absent to numerous, sometimes completely covering the apices; isidiomorphs tufted on soralia, few to numerous. Cortex moderately thin to moderately thick (6l0%), shiny in longitudinal section; medulla moderately thin (1825%), dense to compact; ? irregularly pink pigmented, sometimes not pigmented at all; axis moderately thin to moderately thick (3148%); A/M = 1 .1- 2.7. Apothecia uncommon. Pycnidia unknown.
Chemistry: Usnic acid, diffractaic acid (Hale & Cole 1988, Culberson 1970, Culberson et al. 1977 all fide Posner 1990: 115).
Ecology: Corticolous on Fagus. Widely distributed in boreal and temperate areas of the Northern Hemisphere. It was found only once in the Nordic countries and is now considered extinct.