384 44. PHYSCIACEAE [174. Physcia 



lower cortex often thinner and less well-developed, distinct algal and medullary 

 layers, the margins sometimes ciliate; more or less covered with rhizoids below; 

 apothecia minute to small and middle-sized or rarely large, adnate to sessile, the 

 disk more or less concave to flat or rarely convex, brown to black or pruinose, the 

 exciple colored like the thallus, thick, more or less irregular; hypothecium hyaline 

 to yellowish or brownish; hymenium hyaline or brownish above; paraphyses 

 unbranched; asci clavate; spores 8, brown, oblong to ellipsoid, 1 -septate. 

 The algal host is Protococcus. 



A. Thallus more or less adnate throughout 

 B. Thallus closely adnate 



C. On rocks 2. P. teretiuscula 



C. On trees 1. P. adglutinata 



B. Thallus adnate but not closely so 



C. Thallus more or less sorediate, sometimes rarely so 

 D. Exciple not hispid 



E. Thallus small, becoming granulose or bearing 



massed soredia toward the center 4. P. astroidea 



E. Thallus larger, bearing round soredia 3. P. caesia 



D. Exciple plainly hispid 

 E. Thallus whitish within 



F. Rarely whitish sorediate 6. P. obscura 



F. Commonly greenish sorediate 5. P. virella 



E. Thallus saffron-colored within 7. P. endochrysea 



C. Thallus not sorediate 

 D. Exciple hispid 



E. Spores 20-30 X 10-15 /* 9. P. setosa 



E. Spores 15-23 X 6-10 /* 8. P. lithotodes 



D. Exciple not hispid 



E. Whitish to darker below 



F. Thallus ashy to white; spores 12-20X5-7.5/* . . 13. P. callosa 

 F. Thallus greenish gray to darker; spores 14-24 X 8-11 /* 



G. Margins ciliate 10. P. stellaris leptalea 



G. Margins not ciliate 10. P. stellaris 



E. Brown to black below 



F. Spores 26-32X15-18/* 11. P. venusta 



F. Spores 15-20X7.5-10/* 12. P. obsessa 



A. Thallus ascending, at least toward the margins 

 B. Thallus more or less pruinose 



C. Thallus pruinose, bearing coralloid branchlets or 

 powdery granules or soredia 



D. Thallus bluish pruinose 14. P. isidiigera 



D. Thallus whitish pruinose, margins yellow- 

 powdery or sorediate 15. P. muscigena 



C. Thallus white-pruinose 16. P. pulverulenta 



B. Thallus not pruinose 

 C. Thallus smooth 



D. Lobes inflated and open at the ends 17. P. hispida 



D. Lobes not inflated and open 18. P. Leana 



C. Thallus granulose or sorediate 



D. Thallus small, margins granulose 20. P. tribacia 



D. Thallus larger, margins powdery 19. P. crispa 



1. Physcia adglutinata (Floerke) Nyl, Mem. Soc. Sci. Nat. Cherb. 5:107. 1857. 



Lecanora adglutinata Floerke, Deutsch. Lich. 4:7. 1815. 



Thallus small, foliose, closely adnate to adglutinate, greenish gray, varying 

 toward ashy or brownish, the lobes usually long and branched with entire to crenu- 

 late margins, finally passing toward the center into a granular crust; whitish below 

 or sometimes darker, rarely bearing scattered rhizoids; apothecia minute to small, 

 0.4-1.75 mm. across, sessile, the disk flat, blackish brown, the exciple entire to 

 subcrenulate, scarcely ciliate; spores oblong to ellipsoid, 13-22 X 7-10/*. 



On trees and shrubs, throughout the United States, but more common east of 

 the Rocky Mountains and north of the Gulf states. 



