158. Alectoria ] 40. USNEACEAE 341 



1. Dufourea madreporiformis (Wulf.) Ach., Lich. Univ. 525. 1810. 



Lichen madreporiformis Wulf., in Jacq., Coll. Bot. 3:105. 1789. Cetraria madre- 

 poriformis (Wulf.) Mull. Arg. 



Thallus of medium size, straw-colored, smooth, erect, usually tufted, swollen 

 and hollow, roughly finger-shaped, passing into dichotomous, short, nodulose, 

 bluntly tipped branches; apothecia lateral; spores ellipsoid, 7-8 X 3-4 fx. 



On soil, mountains of Colorado and California. Apothecia were not seen and 

 their presence is doubted for this species by some authors. 



158. Alectoria Ach., Lich. Univ. 120. pi. 13, f. 1-4. 1810. 



Thallus fruticose, cylindrical to flattened-cylindrical, erect, spreading or hang- 

 ing, branching dichotomous or subdichotomous, cortex of a thick layer of densely 

 packed, stout, parallel, longitudinal hyphae, center of the cylinder hollow, sur- 

 rounded by the medulla of loosely interwoven hyphae; color from greenish gray 

 or straw-color to blackish brown; apothecia usually rare, lateral or subterminal, 

 immersed to more commonly sessile, the disk differing in color from the thallus, 

 the exciple usually entire; the hypothecium and hymenium hyaline, or the latter 

 somewhat colored, especially above; paraphyses unbranched or but slightly 

 branched; spores non-septate, hyaline to brownish or brown. 



The algal host is Protococcus, and the algae lie in scattered clusters within the 

 medulla just within the cortex. 



A. Thallus erect to prostrate or rarely hanging 

 B. Thallus usually dark brown throughout 



C. Apices furcate, without soredia 1. A. divergens 



C. Apices simple, sorediate 4. A. chalybeiformis 



B. Thallus straw-colored or greenish to dark brown 



C. Apices commonly grayish or yellowish 3. A. bicolor 



C. Apices commonly dark brown or blackening 



D. Thallus straw-colored or greenish 8. A. ochroleuca 



D. Thallus chestnut-brown or darker 7. A. nigricans 



A. Thallus rarely prostrate to commonly hanging 

 B. Thallus usually dark brown throughout 



C. Slender throughout 2. A. jubata implexa 



C. Stout with slender tips 



D. More or less white-sorediate 



E. Exciple entire 2. A. jubata 



E. Exciple ciliate 6. A. oregana 



D. Yellow-sorediate 5. A. Fremontii 



B. Thallus rarely dark brown 



C. Sulphur-green tinged with brown 10. A. virens 



C. Straw-colored to greenish, or sometimes blackening . . . 9. A. sarmentosa 



1. Alectoria divergens (Ach.) Nyl., Mem. Soc. Imp. Sci. Nat. Cherb. 3:171. 1855. 



Comicularia divergens Ach., Meth. Lich. 303. 1803. 



Thallus medium length, erect to prostrate, tufted, becoming rigid, smooth, 

 often shining, pale chestnut-brown to blackish brown, dichotomously much- 

 branched, branches widely divergent, slender, rough, subangular and cylindrical 

 to flattened, flexuous,< twisted, the tips long and slender with curved forks; apothe- 

 cia middle-sized to large, 4-9 mm. across, lateral, the disk convex, chestnut-brown 

 to darker, the exciple crenulate, becoming rough externally; spores ellipsoid, hyaline, 

 8-10 X 4.5-5.5 fi. 



On soil and rocks, Oregon, confined to high altitudes and latitudes. 



2. Alectoria jubata (L.) Ach., Lich. Univ. 592. pi. 13, f. 2. 1810. 

 Lichen jiibatus L., Sp. PL 1155. 1753. A. jubata var. prolixa Ach. 



Thallus prostrate to more commonly hanging, becoming much elongated, rarely 

 white-sorediate, freely branching subdichotomously, greenish gray to more com- 

 monly brown or blackening, cylindrical, the branches sometimes entangled; apo- 

 thecia rare, small, 2-3 mm. across, the disk flat to convex, chestnut-brown, the 



