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DescriptionThallus: umbilicate, mono- or polyphyllous, +circular to irregular in shape, coriaceous, rigid, often folded and with a wavy margin, 2-4(-6) cm in diam.; upper surface: medium gray to brown, smooth, sometimes undulating around center; medulla: white; lower side: black, trabeculate (plate-like structures) around umbilicus, covered with numerous short, stout black rhizinomorphs with multicellular thalloconidia; Apothecia: very rare, black, sessile, gyrose, up to 1.5 mm in diam.; asci: clavate, 8-spored; ascospores: brown, muriform, ellipsoid, 8-15 x 4-9 µm; Thalloconidia: multicellular, large, irregular, released from the short rhizinomorphs on the lower cortex; Spot tests: medulla K-, C+ red, KC+ red, P-; Secondary metabolites: gyrophoric, lecanoric and crustinic acids.; Substrate and ecology: on siliceous rocks, on wind-swept boulders in the lowe alpine zone,, usually above the snow in winter; World distribution: Europe, Asia, Africa, and North and South America; Sonoran distribution: rare, southeaastern Arizona.; Notes: With its typically gray upper surface Umbilicaria cinereorufescens is related to U. vellea, which is usually easily distinguished by having thin, white rhizinomorphs in addition to the black, stout, thalloconidiogeneous ones.