Parmelia squarrosa
Parmelia squarrosa photo by Ray Showman
DIAGNOSTIC FEATURES: Squarrosely branched rhizines; lobes patterned-maculate; isidiate; medulla K+ yellow turning red; compare with Parmelinopsis minarum, C+, P. sulcata, which is sorediate, and P. saxatilis very similar but with rhizines simple and unbranched (not known from Ohio).
ECOLOGY: An eastern US species common on trees, more rare on rocks; scattered in Ohio but more common in the east and southeast.