Usnea subgracilis Vain. = Usnea schadenbergiana sensu P. Clerc (non Göpp. & Stein)

    Thallus shrubby, to 20-25 cm long, branches rather smooth, branching base concolourous sometimes light brown-orange but not blackened, overall colour pale cream-greyish, with green tinge when wet. Main branches cylindrical with conspicuous transverse rings, notably towards the base, without papillae, warts and seldom isidia, sometimes rare puctiform soralia, flatenned, whitish, and small curved fibrils, cortex thick, medulla whitish. Apothecia unknown. Photobiont: trebouxioid. Several chemotypes exist, and in France the following: C-, K+/- yellow, KC-, Pd+ yellow-orange. Rare, usually on trees, but in our propection area, on vertical walls of schist rocks of rocky ridges in the Arrée Mounts. Not to be confused with Usnea flammea. N.B. This species was identified by P. CLERC.