100 15. GRAPHIDACEAE [50. Opegrapha 



a very obscure, depressed, black line, the exciple black and rather thin; hypothe- 

 cium hyaline; spores cylindrical-ellipsoid to variously curved and rarely thicker 

 in some regions between the two ends, 3-5-septate, 14-24 X 2—4 ft. 

 On trees, Louisiana. 



12. Opegrapha lithyrga Ach., Lich. Univ. 247. 1810. 

 0. vulgata var. lithyrga (Ach.) Nyl. 



Thallus thin, smooth, greenish gray, varying toward whitish or brownish, some- 

 times disappearing; apothecia rather short and of medium width, 0.4-2 X 0.2-0.3 

 mm., round to oblong-ellipsoid, adnate, scattered to rarely clustered, rarely stel- 

 lately so, straight to curved, rarely branched, the disk narrowly open, flat and dull 

 black, the exciple black; spores narrowly fusiform, 4-5-septate, 19-27 X 3-4 /x. 



On rocks and adjacent trees, near Weymouth, Massachusetts. 



13. Opegrapha astraea Tuck., Lich. Calif. 33. 1866. 



Thallus thin, smooth to slightly rough, pale greenish gray to ashy, often limited 

 more or less by a blackish line, rarely disappearing; apothecia of moderate length 

 and width or rarely subcircular, 0.5-3 X 0.2-0.4 mm., the ends obtuse; partly 

 immersed to adnate, scattered to clustered, usually curved or flexuous, often 

 branched and becoming radiately so, the disk closed to narrowly open, black or 

 more commonly whitish pruinose, the exciple black or likewise whitish pruinose; 

 hypothecium brownish black; spores hyaline or finally brownish, finger-shaped, 

 3-5-septate, 16-26 X 5-7.5 /x. 



On trees, South Carolina, Florida, and Louisiana. 



14. Opegrapha cinerea Chev., Journ. Phys. Chem. Hist. Nat. 94:41. 1822. 

 Thallus thin, smooth, pale greenish gray to whitish or brownish; apothecia 



somewhat elongated but narrow, 0.4-2 X 0.15-0.25 mm., oblong-ellipsoid, slightly 

 immersed to adnate, scattered to more closely placed, usually curved or flexuous, 

 infrequently branched, the disk closed, the exciple black; hypothecium rather thin, 

 brownish black; spores spindle-shaped to narrow-ellipsoid, 3-6-septate, 20-30 • 

 2.5-3 jx. 



On trees, Florida. 



15. Opegrapha lichenoides Pers., Ann. Bot. Usteri 7:30. pi. 1. f. Ab. 1794. 

 O. atra, lichenoides (Pers.) Hasse. O. varia var. not ha (Ach.) E. Fries. 

 Thallus smooth, thin to moderately thick, pale greenish gray, varying toward 



ashy; apothecia rather short but of medium width, 0.5-1 X 0.15-0.35 mm., oblong- 

 ellipsoid, subsessile, commonly scattered, straight to curved, the disk soon open, 

 flat, dull black or obscurely greenish pruinose, the exciple of the same color; 

 hypothecium brownish black; spores fusiform, 3-5-septate, 23-28 X 6-8 /t. 

 On trees, throughout the United States. 



lb. Opegrapha diaphora Ach., Meth. Lich. 19. 1803. 



Lichen diaphorus Ach., Lich. Suec. 20. 1798. 



Thallus thin, smooth, pale greenish gray to ashy, becoming obscurely chinky 

 and sometimes scurfy; apothecia short and narrow, 0.3-1 X 0.1-0.25 mm., ellip- 

 soid-fusiform, slightly immersed to adnate, usually scattered, straight to infre- 

 quently and obscurely curved or flexuous, the disk closed to slightly or more 

 widely open and black, the exciple black, often dull; hypothecium brownish black; 

 spores ellipsoid-dactyloid, 3-7-septate, 16-28 X 4.5-7 p. 



On trees, Massachusetts, California, and Washington. 



17. Opegrapha leucoplaca Mull. Arg., Bull. Herb. Boiss. 3:42. 1895. 



Thallus rather thick, with plainly marked margins, smooth, white, becoming 

 obscurely powdery; apothecia of moderate length and width, 0.4-1.7 X 0.17-0.25 

 mm., oblong- to linear-ellipsoid, partly immersed to adnate, scattered or rarely 

 clustered, straight to curved or obscurely flexuous, rarely 1 or more times branched, 



