Xanthoparmelia mexicana

Xanthoparmelia mexicana (salted rock-shield) is a foliose lichen that grows in 4–10 cm diameter rosettes of gray-green to yellow-green lobes in arid climates all over the world. It grows on acidic rock and soil, in open and arid habitats all over the world. It may loosely cling to the substrate (adnate). It grows in 4–10 cm diameter rosettes of lobes, with lobe tips lighter in color than the center of the rosette. The lower surface is pale to medium brown. Apothecia are uncommon, with cinnamon to dark brown discs, smooth margins, and no pruina. Lichen spot tests are negative for the upper cortex (K-, C-, KC-, P-). For the medulla they are K+ yellow to dark red, C-, KC-, and P+ orange. It produces secondary metabolites including usnic acid and salazinic acid. In the Sonoran Desert, it may be the most commonly found member of its genus.