230 



Figure: Dill., Hist. Muse. PI. 21. f. 56A. 1741. 

 Howe, Bot. Gazette, 56: 499./. 2. 1913, of type. 



Diagnosis: Thallus subfoliaceous, bifacial, subcanaliculate, 

 reticulate-lacunose, stramineous. 



Description: typical: Thallus fruticose to subfoliose (max. 

 alt. 7.5 cm.), rigid, stramineous to pale virescent, often 

 stained below; cortex reticulate-lacunose; branches bi- 

 facial, subcanaliculate, pinnate-lacerate (max. width i 



Fig. 10. Range of Cetraria nivalis (L.) Ach. 



cm.), margins lacerate, rarely subspiculose at the apices 

 (spicules often black tipped). Apothecia rare, adnate, 

 subterminal, ample (max, diam. 8 mm.), convex, margins 

 crenulate, disk pale chestnut. Spores 7-8 X 3-4 m- 



Contingent phases: (a) Degenerate, pulvinate. 



Substrata: On the earth. 



Distribution : Common in the Boreal zone or in alpine regions 

 above 4,000 ft. It occurs from Labrador to Vermont 

 and westward to Colorado, British Columbia and Alaska. 



Observations: This species is sometimes difficult to distin- 

 guish from the preceding, and represents the most foliace- 

 ous species of the genus. Its thallus is nevertheless 

 distinctly radial in structure. 



ExsiccATi: No. 59. Lich. Amer. sept. Exs., Tuck., II & III. 

 1854. "Montium Alborum." 

 No. 14. Lich. Exc, Merr., St. Paul Island, June 19, 1897. 



J. M. Macoun. 

 No. 9. Canadian Lich., Macoun. Rocky Mts., etc. 1885- 



1891. 

 No. 10. Canadian Lich., Macoun. Banff, 1891. 



