214 33. LECIDEACEAE [120. Psora 



furrowed, scattered or clustered, closely adnate or marginally ascendant, white- 

 edged squamules; white below with a few rhizoids; apothecia small to middle- 

 sized, 0.3-1 mm. across, sessile, the disk convex, reddish brown to darker, the 

 exciple thin, lighter brown, finally disappearing; hypothecium yellowish to brown- 

 ish; hymenium pale yellowish to brownish; spores ellipsoid, 9-13 X 4-6 fx. (Plate 

 17.) 



On calcareous rocks, throughout the United States. 



7. Psora anthracophila (Nyl.) Arm, Flora 53:471. 1870. 



Lecidea anthracophila Nyl., Flora 48:603. 1865. Lecidea cladonloides (E. 

 Fries) T. Fries. 



Thallus composed of minute to small, rather thick, polished, round to irregular, 

 greenish gray to dull brownish yellow, finally ascending, imbricated finally and 

 obscurely crenate squamules; apothecia minute to small, 0.2-0.5 mm. across, 

 adnate, the disk flat to convex, reddish brown, the exciple lighter, thin and 

 disappearing; hypothecium brownish; spores oblong, 7-13X2-4 jx, irregularly 

 arranged. 



On old wood, Vermont, Massachusetts, New Jersey, and North Carolina. 



8. Psora Friesii (Ach.) Hellb., Sven. Vet. Akad. Handl. 9:61. no. 11. 1870. 

 Lecidea Friesii Ach., in Liljebl., Utk. Svensk. Flora ed. 3. 610. 1816. Biatora 



Friesii (Ach.) Tuck. 



Thallus composed of minute to small, subadnate, convex, crowded and sub- 

 imbricate, greenish gray to brownish squamules; apothecia small to middle-sized, 

 0.3-0.8 mm. across, sessile, the disk flat to slightly convex, black, the exciple thin, 

 black, persistent and becoming more or less flexuous; hypothecium brownish to 

 dark brown; hymenium yellowish; spores ellipsoid, 7-8.5 X 3-4 jx. 



On old wood, Vermont, Massachusetts; doubtfully reported from California. 



9. Psora icterica (Mont.) Mull. Arg., Flora 71:45. 1888. 



Biatora icterica Mont., Ann. Sci. Nat. Bot. II. 2:373. 1834. Lecanora Wrightii 

 Tuck. Biatora Wrightii Tuck. Lecidea icterica (Mont.) Tayl. Lecidea endo- 

 chlora Tayl. 



Thallus composed of small, smooth or furrowed, round to extended, scattered 

 or crowded and imbricated, closely adnate, greenish yellow to tawny, sometimes 

 marginally ascending squamules; white below; apothecia small to middle-sized, 

 0.4-1.2 mm. across, sessile, the disk soon convex, dark brown to black, the exciple 

 thin and disappearing; hypothecium brownish to brown; hymenium hyaline to 

 pale brownish; spores ovoid-ellipsoid, 12-18 X 4-7.5 /x. 



On soil, New York and throughout the United States west of the Mississippi 

 River. 



10. Psora crenata (Tayl.) Reinke; Prings., Jahrbuck. Bot. 28:96. f. 33, II. 1895. 

 Endocarpon crenatum Tayl., Lond. Journ. Bot. 6:156. 1847. Biatora crenata 



(Tayl.) Tuck. Lecidea crenata (Tayl.) Stizenb. Lecidea crenata f. dealbata 



(Tuck.) Zahlbr. 

 Thallus composed of thick, middle-sized to large, closely adnate, round to 

 irregular, brownish red or whitish squamules, the squamules depressed at the 

 margins and hollowed at the center; whitish below; apothecia small to middle- 

 sized, 0.3-0.8 mm. across, sessile, borne on the margins of the squamules, some- 

 times clustered, the disk flat to convex, brownish black, the exciple thin and 

 disappearing; hypothecium brownish to dark brown; hymenium hyaline to yel- 

 lowish; spores oblong-ellipsoid, 11-17X5-7 jx. 



On soil, Texas, Oklahoma, New Mexico, Arizona, Colorado, and Montana. 



11. Psora caulophylla (Tuck.) Fink n. comb. 



Biatora caulophylla Tuck., Proc. Am. Acad. 12:178. 1877. Lecidea caulophylla 

 (Tuck.) Zahlbr. 



