Usnea hirta (L.) F.H. Wigg.Thallus fruticose-filamentous, greenish, flaccid when wet, usually shrubby, rarely subpendulous, 1-5(-7) cm long (rarely more), branching sympodially, anisotomic-dichotomously with divergent branches. Main branches irregular, clearly segmented, often foveolate or transversally furrowed, the basal part not blackened; lateral branches not narrowed at attachment point. Papillae and tubercles usually absent, when present minute and inconspicuous; fibrils numerous, irregularly crowded, small (<3 mm), isidiomorph-like and spinulose, leaving scars after falling off, where the soralia develop. Soralia punctiform, not larger than half the branch diameter, numerous, producing abundant, scattered or clustered isidiomorphs which are most abundant in terminal parts; when these fall off, the soralia may resemble pseudocyphellae. Cortex thin (3-7% of total thickness of the branch), not cracked, matt to shiny in longitudinal section; medulla white, lax to dense, moderately thick (27-33%); central axis white, rather thin (24-35%); ratio axis/medulla ranging between 0.8 and 1.4. Apothecia rare, lecanorine, 1-3 mm across, subterminal. Photobiont chlorococcoid. Spot tests: cortex K-, C-, P-; medulla K-, C-, KC-, P-. Chemistry: cortex with usnic acid; medulla either with no substance or with fatty acids of the murolic group
