Umbilicaria phaea

Umbilicaria phaea is a brown, umblicate foliose lichen that grows up to 6 cm in diameter, sometimes in colonies covering large patches of desert rocks.^{[1]:127 [2]} One variety that grows in northern California is brilliant red.^[1] It is (monophyllous) with a single 1 - 5 cm flattish leaf-like cap on top of an anchoring stem(umblicate).^[2] The leaflike top is smooth with some lobes, roughly circular, thin, and brittle.^[2] The lower surface is light gray to light brown.^[2] It has up to 2.5 mm black circular to slightly polygonal spots that are the fruiting bodies (apothecia), slightly sunken into the main nonfruiting body part (thallus).^[2] It grows on siliceous boulders in very dry climates of western North and South America, where it is usually the most common member of its genus.^[2]

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