Description: Thallus fruticose, filamentous, pendent, attached by a basal holdfast, to 25 cm long, very variable in colour, usually pale brown but becoming almost black in sun-forms, mostly dull, usually without main branches, irregularly branching with mostly obtuse angles, the branches terete, sometimes twisted or foveolate, 0.1-0.3(-0.5) mm thick. Soralia common, fissural or tuberculate, white, with farinose soredia. Pseudocyphellae usually abundant, fusiform or linear, mostly white and conspicuous, sometimes browned; medulla white, compact. Apothecia very rare (never observed in Italian material), zeorine, with a brown disc and a paler margin, to 2 mm across. Asci 8-spored, Lecanora-type. Ascospores 1-celled, hyaline, subglobose to ellipsoid, 4-6 x 3-5 μm. Photobiont chlorococcoid. Spot tests: chemically variable, with at least 4 chemotypes: 1) cortex, medulla and soralia P+ yellow (psoromic acid), 2) cortex and medulla C+ red, KC+ red (gyrophoric acid), soralia sometimes P+ red (fumarprotocetraric acid), 3) cortex, medulla and soralia P+ red (fumarprotocetraric acid), 4) Cortex and medulla P-, soralia P+ red (fumarprotocetraric acid). Atranorin sometimes present in all chemotypes. Apothecia P+ yellow (psoromic acid).
Note: a cool-temperate to boreal-montane, circumpolar, chemically heterogeneous lichen, most common on branches of coniferous, more rarely deciduous trees in areas with frequent fog; frequent in the Alps, much rarer in southern Italy. The study of Boluda et al. (2019) revealed a strong mismatch between phenotypes and genotypes in Bryoria sect. Implexae, which brought to the reduction from 11 to 4 species. All European species (B. capillaris, B. chalybeiformis, B. implexa, B. lanestris, B. kuemmerleana, and B. subcana) should be considered as synonyms of B. fuscescens. Due to their chemical and morphological differences, I still provisionally maintain these taxa as separate species, although they should be best treated as chemical races or forms of B fuscescens.
Growth form: Fruticose filamentous
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)