138 LICHENS OF THE STATE OF WASHINGTON 



matous cortices, medullary, and algal layers, medulla cottony ; lower surface 

 either lighter or darker than the upper, rhizoids scarce. Apothecia terminal 

 or marginal, circular or irregular in shape, sessile or subpedicellate ; thalline 

 margin present; hypothecium hyaline or pale brown; paraphyses un- 

 branched or rarely branched, conglutinate and septate; asci 6-8-spored, 

 hyaline, nonseptate. Spermatia lateral. 



A. Thallus foliose. 

 B. Bright yellow. 



C. Apothecia usually abundant, margins of thallus never sorediate. 



4. C. juniperina 



C. Apothecia very rare, margins of thallus sorediate 7. C. pinastri 



B. Not yellow. 



D. Some shade of brown. 



E. Margins bearing prominent white soredia ; apothecia rare. 



8. C. scutata 



E. Margins bearing dark papillae ; apothecia common. 



1. C. fahlunensis 

 D. Greenish gray or straw color. 



F. Definitely and deeply reticulate-lacunose, thallus with IKI gives 



no color change. 



G. Lobes narrow, elongated, often pendulous 6. C. stenophylla 



G. Lobes broad and widely spreading. 5. C. lacunosa 



F. Not definitely and deeply reticulate-lacunose, thallus with IKI, 

 blue. 

 H. Lobes narrow, elongated, margins sorediate, often with short, 



jagged coralloid branchlets 3. C. Tuckermani 



H. Lobes broader, short, margins sorediate, isidiose, or with coral- 

 loid branchlets 2. C. glauca 



A. Thallus fruticose to subfruticose. 



I. Yellow, green yellow, or cinnamon bufif, margins never ciliose-spinulose. 

 J. Lobes long and narrow, rarely branched above, margins often join- 

 ing to form a tube 9. C. cucullata 



J. Lobes wider, much branched above, deeply laciniate 14. C. nivalis 



I. Some shade of brown or green, margins always somewhat ciliose- 

 spinulose. 

 K. Thallus blue with IKI, margins abundantly ciliose-spinulose. 



11. C islandica 

 K. Thallus not changing color with IKI, margins sparingly ciliose- 

 spinulose. 



L. Always growing on trees or shrubs 12. C. arhorialis 



L. Never growing on trees or shrubs 10. C. hiascens 



1. Black or very dark brown, margins never ciliose-spinulose. 



13. C. Merrillii 



1. Cetraria fahlunensis (L.) Schaer., Lich. Helvet. Spicil. sect. 4-5, 255. 

 1833. 

 Lichen fahlunensis Linn. Sp. PI. 1143. 1753. 



