Thallus pendent, to 12 cm long; the branching isotomic dichotomous at the base but anisotomic dichotomous toward the apices, angles of the branches mainly acute, branches becoming spirally twisted and contorted to foveo-late, the main branches to 1 mm diameter, often with irregular spinules which are not constricted at the base; thallus dark olive-brown to black, dull; pseudocyphellae lacking; soralia usually sparse, mainly tuberculate, some fissural, white, to 1 mm long. Apothecia unknown. 

Reactions: cortex and medulla K- , C- , KC- , P- ; soralia P+ red.

Contents: fumarprotocetraric acid.

This species grows on conifers and on wood. It appears to be in montane forest in Europe and in North America but with strangely disjunct stations reaching the edge of the Arctic in the Dubawnt Lake area and the west coast of James Bay.