Parmelia sulcata
Parmelia sulcata photo by Ray Showman
DIAGNOSTIC FEATURES: Patterned ridges on lobes; soredia along patterned cracks of surface; medulla K+ yellow turning red; compare with Canoparmelia crozalsiana which has no maculae and is K+ yellow and with Myelochroa aurulenta which is ciliate, has a yellow medulla, and is K-.
ECOLOGY: Widespread in primarily the northern US; very common in Ohio, probably present in every county; on bark, rarely on rock, a pioneer species which seems to prefer twigs and small trees over mature tree boles. This species is tolerant to air pollution.