Ruffled Lichen (Genus Parmotrema) with cilia - 2013-5-12 unknown location in MD

this is a foliose (leafy) lichen
Jim Conrad at backyardnature.net writes:
"...the Perforated Ruffle Lichen's thalli bear something else less commonly observed on foliose lichens, and that's the slender, black, hairlike structures along the ruffled margins of the thalli. Those black hairs are called cilia and in lichen identification they are important because most lichens don't have them, but some do. Moreover, from species to species, the cilia's general appearance and disposition along the thalli margins vary greatly. "
http://www.backyardnature.net/n/x/p-r-lich.htm