Thallus to 1 m or more long in favoured sites, pendent or scrambling, main branches to 3 mm diam., the older portions strongly inflated, ± cylindrical, forming sausage-like segments. Young or terminal branches less inflated, adjacent segments interconnected by a cartilaginous axil or with annulations, sparingly branched at base, more richly irregularly branched towards apices, with few, ± flexuose lateral branches, often in a loose, flexuose tassel. Base brown or concolorous with the main thallus branches. Cortex thin (5-7% of diam.), surface pale to mid green-grey, uniformly smooth or rarely, in part, minutely roughened-papillate, with scattered, slightly raised white, dot-like, comma-like or irregular linear pseudocyphellae. Medulla wide, lax, cottony-arachnoid, especially in inflated parts. On some (often narrower) branches the pseudocyphellae convert into soralia or isidia, the latter sometimes having pigmented apices.
Teleomorph: ascomata unknown in Britain.
Chemistry: Medulla C–, K–, KC–, Pd+ red (fumarprotocetraric and usnic acids).