Usnea articulata (L.) Hoffm.

   Thallus shrubby longly pendent, no visible attachment point to the substratum, main branches filamentous, to 50-60 cm long, 2-3 mm diam., with short and thin spinules, old main branches cylindical, smooth, inflated, with, from place to place, distinctive constrictions where the cartilaginous axil is visible at segments junction, producing a sausage-like aspect (this is a distinctive feature that may be absent in youg specimen), surface sometimes scattered with coma-shaped peudocyphellae, pale grey-green. Fertile specimen unknown in our prospection area. Photobiont: trebouxioid. Medulla: C-, K-, KC-, Pd+ red. Rare and declining in our region as it is one of the most sensitive species to pollution, on branches in crown of big trees and therefore difficult to observe except when trees are cut down or on ground after strong winds. In the past this species had been reported on ground in dunes and capes strongly exposed to wind, but it has been impossible to find it since. Recollect that young specimen lack the characteristic articulations, could be confused with Usnea ceratina (but the central axis of the latter is pink).

N.B. Species sometimes parasitized by Biatoropsis usnearum and by Cyphobasidium usneicola (muriform galls).