342 Herre 



Lichen vulpinus L. Syst. Nat. ed. lo. 2 : 1343. i759- 

 Evernia vtdpina Ach. Lich. Univ. 443. 18 10. 



2. EVERNIA PRUNASTRI (L.) Acharius. 



Thallus tufted, fruticose, erect or pendulous, angular or 

 flattened : branches numerous, narrow to linear, elongate ; or 

 (forma soredifera Ach.) shorter and much wider lobed, beneath 

 lacunose or channelled ; white or greenish, mealy, lateral and 

 confluent soredia very abundant ; also more or less present in 

 the typical form ; color whitish, pale green, to dark green ; 

 beneath much paler, often white. 



Sterile with us. 



A very common lichen throughout our territory, growing on 

 trees, shrubs, dead wood, fences, roofs, mossy stones. Form- 

 ing conspicuous whitish tufts on twigs. 

 Lichen prtinastri 1^. Sp. PI. 2: 1147. 1753- 

 Evernia ^runastri Kq\\. Lich. Univ. 442. 1810. 



IV. Usnea (Dill.) Ach. 



Thallus shrub-like and erect or excessively elongated lax 

 and pendulous, terete, much branched, smooth or roughened, 

 with or without many short fibrils ; medullary layer solid, white, 

 cord-like ; color pale gray, silver-green, or straw-color, except 

 in one form which is red ; alike on all sides. Apothecia tan, 

 pale flesh-color, or concolorous, orbicular, peltate, terminal or 

 lateral ; the margin radiately fibrillose ; spores simple, color- 

 less, ellipsoid, small. 



On trees and shrubs throughout ; occasional on old fences 

 and roofs. Reaching the maximum thalline development and 

 number of species at high altitudes where exposed to fog. 



The species not always well defined and apparently inter- 

 grading. One species not heretofore described is rather com- 

 mon over part of our territory. 

 Usnca Dillenius, Muse. 56. 1741 ; in part. 

 Usnea Ach. Meth. Lich. 306. 1803. 



KEY TO THE SPECIES. 



a. Plants small, erect, shriib-like. 

 b. Color gray-green. 



c. Without soredia i. Jforida, 343. 



