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Physcia caesia (Hoffm.) Furnr.
Family: Physciaceae
[Borrera caesia (Hoffm.) Mudd,  more]
Physcia caesia image
Stephen Sharnoff  
Thallus: orbicular to irregular, to 5 cm diam. lobes: up to 3 mm, usually narrower, sometimes overlapping, sometimes distinctly separated, eciliate upper surface: gray to dark gray with white maculae soredia: in marginal to ± laminal, often capitate soralia upper cortex: paraplectenchymatous medulla: white lower cortex: prosoplectenchymatous with the lowermost part gradually forming rounded, isodiametric cells lower surface: white to dark gray with dark, sometimes with black rhizines Apothecia: not seen in the Sonoran Desert material, elsewhere common to rare, sessile, up to 1.5 mm wide, margin: entire or crenulate; disc: brown-black, sometimes pruinose; hymenium: hyaline below, brownish above; hypothecium: hyaline or yellowish; paraphyses: simple or rarely branched, capitate ascospores: brown, 1-septate, Physcia-type, 17-24 x 7-11 µm Pycnidia: not seen in the Sonoran Desert material, elsewhere rare conidia: subcylindrical, 4-6 x 1 µm Spot tests: upper cortex and medulla K+ yellow, C-, KC-, P+ yellow Secondary metabolites: upper cortex with atranorin; medulla with atranorin, zeorin and sometimes unidentified triterpenes. Substrate and ecology: mainly growing on acid rocks in ± open situations, but it is also known as corticolous (not in the Sonoran Desert) World distribution: widely distributed within the arctic, boreal and temperate vegetation zones Sonoran distribution: one of the most common Physcias on rocks at coastal to high elevations in the Sonoran region from Arizona, southern California, Baja California, Baja California Sur and Sonora. Notes: Physcia caesia may sometimes be difficult to distinguish from P. poncinsii but the characteristic crateriform soralia and the distinctly convex lobes of the latter make them easy to separate.
Physcia caesia image
Troy McMullin  
Physcia caesia image
Lucy Taylor  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
Stephen Sharnoff  
Physcia caesia image
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Andrew Khitsun  
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Andrew Khitsun  
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