292 37. PERTUSARIACEAE [ 141. Pertusaria 



minute to small, 0.15-0.3 mm. across, 1- rarely 3 or 4 immersed in wartlike eleva- 

 tions, with minute black ostioles or becoming superficial and open, with the disk 

 concave to flat, blackish, the exciple thick, irregular, colored like the thallus, the 

 whole apothecium sometimes passing into a powdery-sorediate heap; spores 1 or 

 2, ellipsoid, 64-96 X 28^10 fi. 

 On trees, Florida. 



12. Pertusaria Finkii Zahlbr., in Fink, Minn. Bot. Stud. 2:696. 1901. 



Thallus thin, smooth or becoming chinky and somewhat warty, ashy to whitish, 

 the wartlike elevations small, irregular, and flattened; apothecia small to middle- 

 sized, 0.3-0.6 mm. across, immersed 1-5 in each flat and inconspicuous elevation 

 with minute, irregular, brown or blackish ostiole, or becoming open with a concave, 

 brown to blackish disk; spores 2 or rarely 1, oblong-ellipsoid, sometimes constricted 

 along the sides, 70-140 X 28-53 fi. 



On trees, Minnesota. 



13. Pertusaria leioplaca (Ach.) Lam. & DC, Fl. Fr. ed. 3. 6:173. 1815. 

 Porina leioplaca Ach., Lich. Univ. 309. pi. 7, f. 2. 1810. 



Thallus thin, smooth to slightly chinky and warty, greenish gray to yellowish, or 

 rarely imbedded in the substratum and invisible; apothecia small, 0.25-0.4 mm. 

 across, 1- rarely 5 immersed in each small to middle-sized, round, irregular, wart- 

 like elevation, the ostioles minute, black, becoming prominent, or the apothecia 

 rarely becoming open with blackening disk and thick, irregular exciple; spores 

 4-8, oblong-ellipsoid, 44-180 X 20-50 /x. 



On trees and rocks, throughout the United States. 



14. Pertusaria marginata Nyl., Lich. Jap. 53. 1890. 

 P. torquata Mull. Arg. P. propinqua Mull. Arg. 



Thallus thin, smooth to wrinkled, becoming chinky-areolate and warty, grayish 

 white to whitish, the wartlike elevations irregular, with margins wholly or in part 

 swollen and raised; apothecia small, 0.3-0.5 mm. across, 1-several immersed in each 

 wartlike elevation, the ostioles black, subdepressed, commonly converging and ap- 

 pearing disklike with a thick, irregular, swollen exciple; spores 4-8, ellipsoid, 72- 

 110 X 28-42 ix. 



On trees and rocks, from Massachusetts to the Carolinas. 



15. Pertusaria pertusa (L.) Tuck., Enum. N. A. Lich. 56. 1845. 



Lichen pertusus L., Mant. PI. 131. 1767. P. communis Lam. & DC. Porina 

 pertusa (L.) Ach. P.rupestris (DC.) Schaer. 



Thallus thin to rarely moderately thick, smooth, becoming wrinkled or warty 

 and subareolate, greenish gray or lighter colored, and rarely zonate toward the 

 circumference, the wartlike elevations subglobose, somewhat depressed, variously 

 irregular; apothecia small to middle-sized, 0.4-0.6 mm. across, 2-several immersed 

 in each elevation, the ostioles minute and often inconspicuous, sunken, blackish to 

 black; spores 2 or rarely 3 or 4, oblong-ellipsoid, 90-200 X 40-70 /x. 



On trees and rocks, throughout the United States. 



16. Pertusaria Wulfenii Lam. & DC, Fl. Fr. ed. 3. 2:320. 1805. 

 Porina fallax Ach. 



Thallus thin to rather thick, smooth to wrinkled and warty, sulphur-colored to 

 ashy yellow; apothecia small to middle-sized, 0.4-1 mm. across, 1-several immersed 

 in small to middle-sized wartlike elevations, the few to many black ostioles running 

 together into a depressed but flat blackish disk with a thick, wavy to flexuous, 

 thalloid exciple; spores 8, ellipsoid, 58-110 X 28-42 jx. 



On trees, throughout the United States. 



17. Pertusaria glomerata (Ach.) Schaer., Lich. Helv. Spic. 66. 1826. 

 Porina glomerata Ach., Lich. Univ. 310,311. 1810. 



Thallus thin to moderately thick, round, composed of minute to small, sub- 



