Usnea rubicunda Stirt

    Thallus shrubby, to 10-12 cm, more or less erect or pendulous, overall cortex typically redish, orange, bright rusty, fire, colour conspicuous notably on main branches towards the base (base not blackened), irregular branching at right angle giving rise to secondary branches. Main branches covered with tuberculate isidia, suggesting soredia when old and with long (to 1 cm) perpendicular fibrils. According to the literature, absence of fruiting bodies but fertile specimen have been found: see Usnea rubicunda forme fertile. Photobiont: trebouxioid. Two chemotypes are known: 1) Medulla: C-, K+ orange, KC-, Pd+ orange and 2) Medulla: C-, K+ yellow > red, KC-, Pd+ orange. Found on tree barks (notably deciduous trees) in windy oceanic woodlands and also typically in our prospection area, on ground in highly exposed and windy heathlands near the seashore notably capes and heads (see: Usnea rubicunda forme des sols). N.B. Not to be confused with other species with reddish aspect due to alteration and notably Usnea cornuta that is rather similar (but in the case of thallus alteration, the red colour is not restricted to the cortex as for Usnea rubicunda).