Description ²

 Thallus: umbilicate, monophyllous, +somewhat lobate, +circular, brittle, thin, rigid, usually with an entire margin, 1-3(-5) cm in diam.; upper surface: light to medium brown, shiny, smooth but with irregular, thin, black cracks in the surface giving a chinky appearance, usually epruinose; medulla: white; lower surface: light gray to light brown, sometimes black around the umbilicus, coarsely papillate; Apothecia: common, black, immersed to sessile, circular or angular, with gyrose disc often with many small circular elevations, up to 2.5 mm in diam.; ascospores: hyaline to light brown, simple, ellipsoid, 8-16 x 4-9 µm; Spot tests: K-, KC+ red, C+ red, P-; Secondary metabolites: gyrophoric, lecanoric and umbilicaric acids.; Substrate and ecology: on siliceous boulders in very xeric microhabitats; World distribution: western North and South America; Sonoran distribution: occurring in many localities, from near the seashore to high mountains in Arizona, southern California and Baja California.; Notes: Umbilicaria phaea is the most widespread rock tripe in the area, something that reflects its ability to grow in very dry habitats. A disjunct specimen of U. phaea var. coccinea Llano is reported for northern Baja California (Llano 1950), although this distinctive red-colored taxon primarily occurs in the Pacific Northwest. The common name of U. phaea is emery rock tripe. 

Sources and Credits

1. (c) Jason Hollinger, some rights reserved (CC BY), http://www.flickr.com/photos/7147684@N03/1289867490
2. (c) Lichen Unlimited: Arizona State University, Tempe., some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/10548739

More Info

• iNat taxon page
• Biodiversity Heritage Library
• BOLD Systems BIN search
• CalPhotos
• Global Biodiversity Information Facility (GBIF)
• Mushroom Observer
• NatureServe Explorer 2.0
• SEINet Symbiota portals
• USDA PLANTS database
• Ways of Enlichenment

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