Thallus cushion-like, often forming extensive colonies; thallus thin, delicate, lobes narrow; rhizines absent or sparse, usually not visible from above; soredia
formed at lobe tips, powdery Xanthomendoza fulva 1.
This member of the former Parmelia subtinctoria group is characterized by a uniformly brown, rhizinate lower surface with broad, rounded lobes producing marginal cilia and soredia.
physodes, with soredia under expanded, labriform lobe tips, from extreme western Nebraska, and we have numerous records of that taxon from recent collections.
subargentifera, which has laminal and marginal soredia and an upper cortex that is often pruinose with fine colorless hairs on the lobe tips.
A common species through the eastern United States and adjacent Canada, characterized by the abundant rhizines and coarse, isidioid, marginal soredia.
dimidiata produces rather broad lobes, an abundance of pruina on the surface, and marginal soredia.
Thallus lacking soredia or isidia Physconia muscignea (Ach.
Lobe tips of thallus with pale, cortical hairs; soredia marginal Phaeophyscia hirsute 3.
5 mm wide; medulla and soredia K-; soredia granular Physcia millegrana 3.
6 mm wide; rhizines absent or sparse, usually not visible from above; powdery soredia formed at lobe tips Xanthomendoza fulva 1.