Pleopsidium flavum
Pleopsidium flavum is a distinctively colored, bright lemon-yellow to chartreuse crustose lichen that grows in high elevations on vertical or overhanging hard felsic rock in western North America. Its thallus grows in a circular outwardly radiating pattern, with 1mm wide lobed edges.
This is the identity of the vivid, lime-green lichens often photographed on granite boulders in the Wichita Mountains Wildlife Refuge of Oklahoma.
It was formerly classified as Acaraspora chlorophana. It is in the Pleopsidium genus of the Acarosporaceae family.
It is similar to Acarospora schleicheri, which grows on soil and rarely on rock, and to Pleopsidium chlorophanum, which favors dry arctic or alpine sandstone cliffs and boulders.
