50. Opegrapha] 15. GRAPHIDACEAE 101 



the disk closed, the exciple black; hypothecium brownish black; spores fusiform, 

 3-7-septate, 16-23 X 3.5^.5 jx. 

 On trees, Florida and Louisiana. 



18. Opegrapha varia Pers., Ann. Bot. Usteri 7:30. 1794. 



0. pulicaris (Hoffm. ) Schrad. 0. varia var. pulicaris (Hoffrn.) E. Fries. 



Thallus thin, smooth, or becoming thicker and obscurely chinky or powdery, 

 pale greenish gray to whitish, rarely disappearing; apothecia rather short and 

 wide, 0.4-2 X 0.16-0.4 mm., the ends often more or less pointed, partly immersed 

 to adnate, scattered or clustered, straight to infrequently and obscurely curved 

 or even rarely flexuous, the disk closed to soon open, slightly concave to convex, 

 dull black, the exciple black, at first thick, prominent and inflexed, finally tending 

 to disappear; hypothecium moderately thick, brownish black; spores hyaline to 

 finally brownish, fusiform, varying toward oblong-ellipsoid, 3-5- or rarely 7-septate, 

 18-30 X 5-8 /x. 



On trees, throughout the United States. 



19. Opegrapha vulgata Ach., Lich. Suec. 21, 22. 1798. 

 O. vulgata var. subsiderella Nyl. 



Thallus thin, smooth, becoming chinky, scaly, powdery, light greenish gray, 

 varying toward ashy white or brownish; apothecia short to elongated but remain- 

 ing narrow, 0.4-5 X 0.15-0.25 mm., the ends usually obtuse, slightly immersed to 

 adnate, scattered or clustered, straight to curved or flexuous, rarely branched, the 

 disk closed to rarely and narrowly open, slightly concave to flat and dull black, 

 the exciple rather thin and black; hypothecium brownish black; spores narrowly 

 fusiform, 4-7-septate, 16-28X3-4 /a. 



On trees, distributed throughout the United States, but not common in most 

 areas. 



var. minor Mull. Arg., Bull. Herb. Boiss. 3:42. 1895. 

 Apothecia on the whole shorter and narrower, the disk tightly closed and ob- 

 scurely visible. 



On trees, Louisiana and Florida. 



20. Opegrapha longissima Mull. Arg., Bull. Herb. Boiss. 3:43. 1895. 

 Thallus thin, smooth, continuous to sparingly and obscurely chinky or rarely 



becoming irregularly areolate, pale greenish gray to whitish, rarely tending to dis- 

 appear; apothecia becoming very long but only moderately wide, 1.5-6 X 0.25-0.35 

 mm., with obtuse ends, immersed in the thallus and the substratum or becoming 

 partly superficial, numerous, straight to infrequently curved, usually approximat- 

 ing parallel position and closely aggregated, the disk soon open and flat, dull 

 brownish black or often obscurely whitish pruinose, becoming several to many 

 times transversely fissured, the exciple black or obscurely whitish pruinose laterally, 

 and often covered toward the base by a thalloid one; hypothecium hyaline; spores 

 fusiform, usually 5-septate, 16-20 X 4-5 p. 



On decorticated wood, near St. Martinsville, Louisiana. 



21. Opegrapha Hassei Zahlbr., Ann. Myc. 10:365. 1912. 



Thallus thin to moderately thick, smooth, becoming chinky to subareolate, 

 rough and crumbling, or finally powdery, dull dirty whitish, resting on a very 

 thin, grayish, lead-colored hypothallus, the margin becoming obscurely lobulate; 

 apothecia of moderate length but rather wide, 1.5-4 X 0.4-0.8 mm., more or less 

 irregular with obtuse ends, adnate to subsessile, scattered or clustered, curved 

 more or less strongly, becoming 1 or 2 times branched furcately, the disk open, 

 flat, brown to brownish black, more or less grayish pruinose, the exciple thick, 

 dark brown to blackish, thick, more or less irregularly covered toward the base 

 by a thalloid one; hypothecium hyaline or tinged more or less with brown; spores 

 oblong-dactyloid, usually 7-septate, 15-24 X 3.5-5.5 /x. 



On rocks, Santa Catalina Island, California. 



