Thompson, J., 1984. American Arctic Lichens: The Macrolichens.
Thallus erect to decumbent or subpen-dent, 4-6 cm long; the branches isotomic di-chotomous toward the base, becoming anisotomic dichotomous toward the apices, the angles between the branches usually acute; branches terete, even in diameter, sometimes slightly compressed toward the base, to 0.4 mm diameter, the base becoming black, the apical branches paler than the base, pale brown to brown, some lateral spinules at right angles to the main stems; pseudocyphellae sparse to abundant, fissural, usually dark; soralia lacking. Apothecia known only from one collection from Alaska; lateral, margin concolorous with the thallus, becoming excluded, concave to becoming convex; disk yellowish brown to reddish brown, to 1.5 mm broad; spores 8, hyaline, simple, subglobose, 7-9.5 x 5-7 μ.
Reactions: inner cortex and medulla K- , C- , KC- , P+ red at least in part.
Contents: fumarprotocetraric acid.
Growing on mosses on trees and on rocks, also in rock crevices, this species is reported as being oceanic in Europe, Greenland, and North America where it ranges south into the Appalachian Mountains, in Alaska and British Columbia, and inland in the District of Keewatin. It is a poorly known, seldom collected species.