pebble ball lichen

Circinaria arida (pebble ball lichen) is a .5-6 cm, light olive-brown custose lichen that grows on rock, often like a cluster of little light brown to olive balls growing on pebbles, in the southwestern deserts of North America. It is also found in Eurasia, and arid parts of North America from the southern Great Plains and Midwest to California. It is warty (verrucose)with the warts sometimes cracking apart areolate. The warts or areolas have angular to...