Field Key to Common Gray Narrow-Lobed Foliose Lichens

1a Lower surface brown to black……………………. 2

1b Lower surface white, tan, or less commonly yellow……………………………………………………. 8

2a Medulla white………………………………………….. 3

2b Medulla yellow or yellowish (sometimes faintly so, and only beneath soredia or apothecia)………………………………………………. 5

3a Thallus lacking lichenized asexual propagules but older specimens wrinkled in the center; apothecia common and abundant; rhizines with forked tips……………. Hypotrachyna livida

3b Thallus isidiate or sorediate……………………….. 4

4a Thallus very prominently isidiate, appearing almost prickly; apothecia rare; rhizines simple to squarrosely branched…………. Hypotrachyna minarum

4b Thallus sorediate; upper surface very strongly pruinose, appearing frosted Physconia detersa, P. leucoleiptes

5a Soredia lacking; apothecia abundant; upper surface epruinose; rhizines simple; older specimens wrinkled in the center.. Myelochroa galbina

5b Soredia present; upper surface smooth………… 6

6a Lobe tips with patterned ridges……….. Parmelia sulcata

6b Lobe tips pruinose……………………………………. 7

7a Thallus tightly appressed; lobe tips flat or turned down; soredia located both along lobe margin and surface; pruinia uniformly covering tops of lobe tips like icing on a cake; UV………………………… Pyxine subcinerea

7b Thallus adnate to substrate but not especially tightly appressed; soredia predominantly on lobe margins only; pruinia “salted” on lobe tips; UV+ brilliant yellow…… Pyxine sorediata

8a Lower surface ecorticate, appearing soft, yellow-orange………… Heterodermia obscurata

8b Lower surface corticate, white or light tan…… 9

9a Margins with projecting cilia or cilialike rhizines………………………………………………… 10

9b Margins without projecting rhizines or cilia. 11

10a Lobe tips fist-shaped, with open ends revealing soredia within; surface strongly maculate………………………. Physcia adscendens

 

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10b Lobe tips flat, with lip-shaped soralia at branch tips; surface lacking maculae………………………………. Heterodermia speciosa

11a Thallus lacking lichenized asexual propagules; apothecia abundant………………. 12

1b Thallus isidiate or sorediate; apothecia various……………………………………………………………. 13

12a Apothecia disks black; mainly on small hardwood branches……….. Physcia stellaris, P. aipolia

12b Apothecia disks cream-colored; on pines………………………………… Imshaugia placorodia

13a Isidia covering most of surface; apothecia absent………………………….. Imshaugia aleurites

13b Isidia lacking; soredia present; apothecia various…………………………………………………. 14

14a Soredia presented in capitate soralia on upper lobe surface; apothecia rare; a moderate-sized calciphilic lichen that is infrequently encountered…………………… Physcia americana

14b Soredia distributed along finely divided margins; apothecia common; a small lichen that is extremely abundant on trees in open areas everywhere…………… Physcia millegrana