19. Porina] 4. PYRENULACEAE 53 



A. Spores 1-3-septate 



B. Thallus usually appearing as a coloration of the substratum 



C. Spores 1-septate 1. P. plumbaria 



C. Spores becoming 3-septate 



D. Thallus surrounded by a black hypothallus; 



spores 16-20 X 3.5-6 /x 3. P. subcinerea 



D. Thallus not surrounded by a black hypothallus; 



spores 12-16 X 4.5-6 /u. 2. P. cinerea 



B. Thallus very thin, but persistent 



C. Thallus thin to granulose or scurfy 



D. Thallus granulose; spores 18-30 X 4.5-7 (i 8. P. lectissima 



D. Thallus becoming scurfy; spores 15-23 X 3.5-4.5 n . . 7. P. chlorotica 

 C. Thallus smooth to minutely wrinkled 



D. Spores rarely more than 16 ft in length 



E. Spores 9-10 X 3-4 n 5. P. viridiseda 



E. Spores 13-16 X 4.5-5 m 6. P. salicina 



D. Spores rarely less than 16^ in length 

 E. Thallus dark olive-brown; spores 



15-22 X 4-4.5 /j. 9. P. olivacea microspora 



E. Thallus greenish gray to ashy or brownish; 



spores 18-24 X 5-7.5 fi 4. P. Carpinea 



A. Spores 5- or more- septate 



B. Perithecia 0.3-0.7 mm. across 



C. Spores 40-70X8-11/* 10. P.nucula 



C. Spores 65-92 X 10-12 fi 10- P.nucula heterospora 



B. Perithecia not more than 0.45 mm. across 

 C. Spores 5-8-septate 



D. Thallus blackish green 



E. Spores 30-115 X 2.5-5 fi 12. P. cestrensis 



E. Spores 36-50 X 5-9 fi 12. P. cestrensis platyspora 



D. Thallus greenish gray to ashy or darker 11. P. mastoidea 



C. Spores 7-11-septate 13. P. rhaphidosperma 



1. Porina plumbaria (Stizenb.) Hasse, Cont. U.S. Nat. Herb. 17:12. 1913. 



Verrucaria plumbaria Stizenb.; Hasse, Erythea 3:44. 1893. Verrucaria car- 

 pinea, plumbaria (Stizenb.) Nyl. 



Thallus grayish, rudimentary, the superficial portion sometimes absent, and 

 the imbedded portion indicated at the surface by a light or darker gray coloration; 

 perithecia minute to small, 0.15-0.4 mm. across, the superficial portion hemi- 

 spherical, shiny black, the ostiole minute, sometimes invisible, the wall dimidiate; 

 spores fusiform, larger toward one end, 1-septate, 12-22 X 4-6 //., uniseriately to 

 irregularly arranged. 



On trees, especially Quercus agrifolia, southern California. 



2. Porina cinerea (Pers.) Zahlbr., Cat. Lich. Univ. 1:376. 1921. 



Verrucaria cinerea Pers., Ann. Bot. Usteri 7:28. pi. 3, f. 6. 1794. 



Thallus ashy gray, rudimentary, the superficial portion very thin and disappear- 

 ing, the imbedded portion indicated at the surface as a grayish coloration; peri- 

 thecia minute to small, 0.15-0.35 mm. across, often clustered, the superficial portion 

 hemispherical, black, the ostiole minute and rarely visible, the wall dimidiate; 

 spores hyaline or tinged brownish, spindle-shaped to ellipsoid, finally 3-septate, 

 12-16 X 4.5-6 fi, irregularly arranged. 



On trees, California. 



3. Porina subcinerea (Nyl.) Zahlbr., Cat. Lich. Univ. 1:405. 1922. 



Verrucaria subcinerea Nyl., Mem. Soc. Acad. Maine et Loire 4:37. 1858. 

 Pyrenula subcinerea (Nyl.) Tuck. 



Thallus ashy, rudimentary, surrounded by a black hypothallus, the superficial 

 portion indicated at the surface as an ashy coloration; perithecia minute, 0.1-0.3 

 mm. across, commonly clustered, the superficial portion depressed-convex, black, 

 the ostiole minute, indicated by a whitish coloration and rarely visible, the wall 



