Il8 HERRE 



sparingly branched, the tips attenuate and pointed or obscurely cup- 

 like, usually without squamules, or basally more or less squamulose. 



Common in some form throughout, on dead wood, rotten logs, 

 old stumps, earth, and moss: not infrequent on old roofs. 



Found all over the world in some of its varieties, these intergrad- 

 ing so that Fink says it constitutes "perhaps the most confusing 

 assemblage of lichens known to our flora. " 



GYROPHORACE^). 



Thallus foliaceous, one-leaved to polyphyllous, attached by a 

 central umbilicus; under side naked or more or less fibrillose; an 

 upper and an under cortex present; alga Pleurococcus. Apothecia 

 scattered over the surface, innate, sessile, or elevated-sessile, the 

 proper margin usually black, rarely enclosing a few gonidia beneath; 

 disk seldom smooth, usually gyrose-plicate; asci 1-8 spored; spores 

 colorless or dark, simple, multilocular, and muriform. Three gen- 

 era, of which we have but one. 



XXV. Gyrophora Ach. 

 Gyrophora Ach. Meth. Lich. 100. 1803. 



Characters mostly as above. Asci with 8 spores; these colorless 

 or brown with age, simple, in one species pluri-locular, ellipsoid or 

 oblong, thin-walled, without gelatinous halo; hypothecium brown- 

 ish to black. 



About 35 species common on igneous rocks and sandstone, especi- 

 ally in alpine or far northern regions. 



KEY TO THE SPECIES. 



A . Thallus polyphyllous, often much dissected, naked beneath 



i. polyphylla 



A A. Thallus one-leaved or but little complicate and not dissected. 



B. Under surface naked 2. ph<za 



BB. Under surface with dense black fibrils 3. polyrrhiza 



i. GYROPHORA POLYPHYLLA (L.) Turn. & Borr. 



Lichen polyphyllus Linne, Sp. PI. 2: 1150. 1753. 

 Gyrophora polyphylla Turn. & Borr. Lich. Brit. 214. 1839. 

 Gyrophora polyphylla Herre, Proc. Wash. Acad. Sci. 7: 365. 1906. 

 Umbilicaria polyphylla Tuck. Syn. N. Am. Lich. I: 85. 1882. 



