340 



40. USNEACEAE [ 157. Dufourea 



2. Evernia divaricata (L.) Ach., Lich. Univ. 441. 1810. 



Lichen divaricatus L., Syst. Nat. ed. 12. 713. 1767. 



Thallus flaccid, pendulous, straw-colored, subcylindrical to flattened or angular, 

 wrinkled, the cortex broken annularly, cottony and stringlike within, dichot- 

 omously branched, the branches strongly divergent, long, sometimes beset with 

 prickles, the tips long-tapered, and filiform, darkening; apothecia small to middle- 

 sized, 2-6 mm. across, infrequent, lateral, the disk concave to flat, the exciple 

 finally much wrinkled; spores ellipsoid, 5-10 X 3.5-6 fi. 



On conifers, mountains of Montana, Colorado, and California. 



3 Evernia prunastri (L.) Ach.. Lich. Univ. 442. pi. 10, f. 1. 1810. 



Lichen prunastri L., Sp. PI. 1147. 1753. E. prunastri var. soredufera Ach. 

 E. prunastri var. thamnodes Flot. E. prunastri var. mollis Merrill. 



Thallus tufted, subpendulous to pendulous, rather flaccid and soft, flattened, 

 finally expanded, wrinkled or obscurely pitted, more or less sorediate, dichot- 

 omously much-branched, the branches strongly divergent, the tips forked, green- 

 ish to straw-colored; lighter colored and channeled below; apothecia middle-sized, 

 3-7 mm. across, lateral, the disk concave, the exciple absent; spores short-ellipsoid, 

 5-7 X 3.5-4.5 fi. (Plate 37.) 



On trees and old wood, sometimes on rocks, from Washington to California. 



4. Evernia furfuracea (L.) Mann., Lich. Bohem. 105. 1826. 



Lichen furfuraceus L., Sp. PI. 1146. 1753. E. furfuracea var. olivetorina (Zopf.) 

 Elenk. Parmelia furfuracea (L.) Ach. 



Thallus tufted and ascending to prostrate, or sometimes pendulous, rather rigid, 

 flattened, usually bearing soft scales or coralloid branchlets, dichotomously and 

 subpinnately branched, much divided toward the usually forked tips, greenish gray 

 to ashy; below channeled and obscurely pitted, white and darkening to black; 

 apothecia large, 3-15 mm. across, marginal, the disk concave, the exciple usually 

 persistent; spores short-ellipsoid, 5.5-8 X 3.5-5 jx. 



On trees, from New England to Florida, and westward to Texas and Arizona. 



5. Evernia ceratea (Ach.) Zopf., Beih. Bot. Centralb. 14:107. 1903. 

 Parmelia furfuracea var. ceratea Ach., Meth. Lich. 255. 1803. E. furfuracea 



var. ceratea (Ach.) Opiz. E. furfuracea var. nuda (Ach.) Nyl. 



Thallus tufted and ascending to prostrate or sometimes pendulous, rather rigid, 

 wrinkled, dichotomously and subpinnately branched, sometimes considerably en- 

 tangled, greenish gray to ashy; below channeled toward the base, brown to black 

 and reticulated within the channels; apothecia large, 3-15 mm. across, marginal, 

 the disk concave, the exciple persistent; spores short-ellipsoid, 5-7.5X3.5-5^. 



On trees, from New England to North Carolina, and westward to the Pacific 

 coast (may be merely an old form of Evernia furfuracea). 



var. Cladonia (Tuck.) Fink n. comb. 

 E. furfuracea var. Cladonia Tuck., Syn. Lich. N. E. 12. 1848. Parmelia Cladonia 



(Tuck.) DR. Parmelia furfuracea var. Cladonia (Tuck.) Merrill. 

 Thallus branches smooth, very slender, round above but open and channeled 

 toward the base, more or less interwoven; apothecia absent. 



On trees, from New England to West Virginia, usually at high elevations. 



157. Dufourea Ach., Lich. Univ. 103. 1810. 



Thallus fruticose, dichotomously branched, the cortex of closely packed, spar- 

 ingly branched, longitudinally extending hyphae; medulla of loosely interwoven, 

 branched hyphae, extending in various directions within the cortex, and leaving 

 the center of the cylinder mostly hollow; apothecia with thalloid exciple; hypo- 

 thecium hyaline; paraphyses becoming gelatinized and indistinct; asci broadly 

 clavate; spores 6-8, hyaline, non-septate. 



The algal host is Protococcus. 



