Usnea silesiaca, Usnea silesiaca
Thallus often ± robust, erect, shrubby to pendulous, 6-12 cm long, richly and irregularly branched. Branches rounded, tapered, never constricted at the point of attachment, surface pale green, matt. Papillae and fibrils few, except that main branches are often ± coarsely papillate towards the holdfast. Basal part of thallus black and here and above with numerous annular cracks. Soralia even, ± flat to slightly tuberculate, raised and then concave, large, conspicuous, punctate to transversely elliptical to irregularly rounded, remaining discrete, moderately dense to dense but rarely becoming confluent. Isidiomorphs irregularly present, generally absent on mature soralia. Medulla compact, narrow, cortex thick.
Anamorph: not known.
Teleomorph: not known.
Chemistry: medulla K+ yellow→red, Pd+ yellow-red (salazinic acid).
Listed as Vulnerable [D2] by Woods & Coppins (2012). Considered to be Nationally Rare, and appears in Sect. 2(4) of the Nature Conservation (Scotland) Act 2004.
Differs from U. subfloridana and U. wasmuthii in the soralium type, the more frequent, distinct annulations on the main branches and on the often extended blackened base and the usually paler thallus colour. U. wasmuthii additionally contains barbatic acid.
In GB&I, reported from SW England and W Scotland (Kintyre), recorded in the 19th century also from Kent.
On deciduous trees, shrubs and rock outcrops in windy situations.