Rock Tripe

Rock tripe is the common name for Umbilicaria, a genus of lichen-forming fungi in the family Umbilicariaceae, established by Georg Franz Hoffmann in 1789. These foliose lichens attach to rock surfaces by a single central point resembling a navel, and their photobiont is a green alga of the genus Trebouxia. The genus occurs worldwide and thrives in cold environments, especially alpine, arctic, boreal and Antarctic regions, growing on exposed rock with a high silica content. Slow growing and long lived, rock tripe has served as an emergency food source in northern regions.