138 HERRE 



7. COLLEMA GLAUCESCENS Hoflfm. 



Collema glaucescens Hoffmann, Deutsch, Fl. 2: 100. 1795. 

 Lichen limosus Ach. Lich. Suec. Prodr. 126. 1798, (excl. syn. Col- 

 lema graniformis Hoffm.) 

 Collema limosum Ach. Lich. Univ. 629. 1810. 

 Collema limosum Tuck. Syn. N. Am. Lich. I: 150. 1882. 

 Collema limosum Herre, Proc. Wash. Acad. Sci. 7: 377. 1906 



Thallus thin, small to medium, irregular or scattered, very closely 

 appressed; margin irregularly crenate or dentate-lobulate ; surface 

 smooth, or here and there beset with small ascendant lobules; color 

 black or dark green. 



Thallus mostly disappearing and becoming merely a network or 

 margin about the numerous large, imbedded apothecia; disk mostly 

 flat, reddish or blackening; spores usually in fours in the asci, ellip- 



II "~ 17 

 sold, muriform, P-. 



22 - 35 



On a wet clay bank beside a spring a mile above Wright's Station; 

 altitude about 1200 feet. Probably occurring in similar situations 

 throughout the mountains. 



A lichen of Europe and North America. 



XXXIII. Leptogium (Ach.) S. Gray. 



Collema sect. Leptogium Ach. Lich. Univ. 654. 18 10. 

 Leptogium S. Gray, Nat. Arr. 1: 395. 182 1. 



Thallus mostly foliaceous, but ranging from crustose to fruticu- 

 lose, with a distinct cortex present on the upper side or on both sides; 

 under surface naked or covered with rhizoids which may become a 

 dense close nap or fleece ; color varying from plumbeous, brown, dark 

 green, to black. 



Apothecia scattered over the surface, often crowded, and usually 

 numerous; small, at first innate, then sessile, lecanorine, the disk 

 broad, circular; spores colorless, ovoid, ellipsoid, spindle-shaped or 

 needle-like, straight or curved, often with attenuate tips, 4-locular 

 to plurilocular and muriform. 



Comprising more than a hundred species distributed all over the 

 world, especially in tropical regions, on bark, mosses, earth, and 



