Field Key to Common Broad-Lobed Gray Foliose Lichens

1a Thallus with pores on the upper surface (pseudocyphellae, best seen with hand lens); undersurface pale (genus Punctelia)………….. 2

1b Thallus without pores, but may be uniform or variously cracked, ridged, or white-maculate; undersurface black or nearly so (except in some instances near lobe margins)…………….. 4

2a Thallus isidiate…………………. Punctelia rudecta

2b Thallus sorediate………………………………………. 3

3a Lobules abundant in center of thallus Punctelia missouriensis

3b Lobules absent…………………. Punctelia caseana

4a Upper surface strongly ridged with soredia erupting along the ridges. Crespoa crozalsiana

4b Upper surface not, or only faintly, ridged……. 5

5a Medulla pale yellow (sometimes only under soralia, white elsewhere); a medium-sized species with thallus closely appressed to substrate…………………… Myelochroa aurulenta

5b Medulla white throughout; especially large lichens extended with ascending lobes (genus Parmotrema)…………………………………………… 6

6a Thallus without lichenized asexual propagules; apothecia abundant…. Parmotrema perforatum

6b Thallus sorediate………………………………………. 7

7a Lower surface black with marginal zone ca. 1 cm wide; lobe margins with prominent eyelashlike cilia and linear soralia; overall form very “ruffled”.. Parmotrema hypotropum

7b Lower surface brown in marginal zone; margins eciliate; thallus lobes only moderately elevated (not especially ruffled)… Parmotrema reticulatum