Description: Thallus fruticose, filamentous, forming tufts, attached by a basal holdfast, to 8(-10) cm long, pale to dark brown, shiny, usually without a main branch, isotomic-dichotomously branching, the branches terete, 0.3-0.5 mm thick, often with lateral spinules. Soralia common, fissural, oval to fusiform, even with thallus or mostly somewhat raised, narrower than the branches on which they arise, white, with numerous isidioid spinules. Pseudocyphellae absent; medulla white, compact. Apothecia extremely rare (never observed in Italian material), zeorine, with a pale brown disc, to 2 mm across. Asci 8-spored, Lecanora-type. Ascospores 1-celled, hyaline, subglobose to broadly ellipsoid, 6-7 x 3-4 μm. Photobiont chlorococcoid. Spot tests: cortex, medulla and soralia K-, C-, KC-, P+ red. Chemistry: fumarprotocetraric acid.
Note: a mainly boreal-montane, circumpolar lichen found on isolated conifers near treeline, sometimes on lignum.
Growth form: Fruticose filamentous
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)