Umbilicaria americana, commonly known as frosted rock tripe, is a foliose lichen of rock faces.
Description Umbilicaria americana has been described as looking like "grayish-white potato chips.""Rocky Mountain National Park- Umbilicaria americana (U.S. National Park Service)." Jul 14, 2007.https://www.nps.gov/romo/umbilicaria_americana.htm (accessed Dec 17, 2008). The upper surface is gray with the appearance of white dusting. The lower surface is black. The lobes are 2 to 7 cm in diameter.
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