Placidium arboretum
Placidium arboreum photo by Bob Klips
DIAGNOSTIC FEATURES: Adnate, foliose to squamulose growth habit; embedded perithecia; NIS; on bark. This is the only foliose lichen with perithecia which grows on bark.
ECOLOGY: Widespread in the eastern US but not commonly collected; records from ten Ohio counties; found exclusively on bark, usually that of white oak.