Parmotrema xanthinum
Parmotrema xanthinum photo by Bob Klips
DIAGNOSTIC FEATURES: Yellow-green, ciliate lobes; marginal isidia cylindrical to branched; collected from rock; compare with P. madagascariaceum which is morphologically identical but with medulla KC+ red.
ECOLOGY: Rather rare on trees and rock in southeastern US; recently found in 5 southern Ohio counties, on the base of sandstone cliffs at all locations.