Thallus to 30 cm long, pendant, often rather narrow, composed of usually 4-6 main branches arising from close to the point of attachment. Branches rather thin, 0.2-0.6 mm diam., mostly even in thickness, usually with many short to 1 cm long fibrils arising at right-angles from the main branches, regularly but unevenly distributed along their entire length in a fish-bone-like arrangement. Branching variously sympodial or dichotomous. Thallus surface typically grey-green, often darker in the older parts and blackened towards the base, which may be transversely cracked but not annellated. Main branches typically densely papillate and with tubercles, which usually produce abundant isidia or isidiomorphs and can also occur on side branches where they are usually less frequent, but are absent towards the apices which narrow to a point and are often laterally fractured into ± cylindrical segments. Soralia punctiform. Cortex thick, medulla dense to compact, axis relatively thick.