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Cetraria islaxdica mod. arborialis Merr. 



Synoxy:my: Cetraria Islandica — " aboricola" Tuck. herb. 

 Cetraria Islandica modification arborialis Merr., Bryol. 9: 4. 

 1906. 



Type: No. 7. herb. J. Macoun. 



Type locality: "British Columbia." 



Original description: "Thallus cartilagineous, fohaceous, 

 suberect or now appressed; laciniae plane, variously and 

 irregular^ divided, the apices commonly obtuse, from 

 narrow to sometimes four mm. in breadth, very smooth 

 and shining or sub-opaque; greenish-olivaceous or oliva- 

 ceous-fucescent, the margins of the laciniae either spinulose 

 or not, in the latter case sometimes white-sorediate. 

 Apothecia not observed." .1. c. 



Substrata: On fallen twdgs and bushes (huckleberry). 



Distribution: Alpine above 6,000 ft., from Mt. Tacoma and 

 Olympic mountains, Washington to the Selkirk mountains 

 and Glacier, British Columbia. 



Observations: Th. Fries first recorded (1871) the growth 

 of C. islandica on wood, and Tuckerman indicated speci- 



FiG. 2. Range of Cetraria lemiifolia (Retz.) R. H. Howe, Jr. (reduce to 2 in. wide). 

 Range of Cetraria islandica mod. arborialis Merr. shown with hachures. 



mens from the western United States in his herbarium 

 which had been collected on wood, with the label "abori- 

 cola." It was not, however, until 1906 that Mr. G. K. 

 Merrill gave a "conditional nomination" to such speci- 

 mens. I have had the opportunity to study seven packets 

 of this corticoHne variety through the kindness of Prof. 

 Fink, five of which were collected by himself. Mr. 

 Merrill in litt. to Prof. Fink named a packet of this 



