176 Fernald — Relationships of some American 



the same plants in exposed or alpine situations have the scales 

 brown, chestnut, or even nearly black.* On the Pacific slope 

 of North America, especially from the Cascade and Coast 

 Ranges to the coast of Oregon, Washington, British Columbia 

 and Alaska, this tendency is likewise very conspicuous. It is 

 well shown in such plants as Carex jpraticola^ Rydb., in the 

 Vancouver Island form described as C. jpratensis^ v^iwfurva, 

 Eailey ; C. pennsylvanica, in the variety vespertina^ Bailey ; 

 C. aitrea, in the Vancouver plant, and in Suksdorf's No. 35 

 from Falcon Valley, and F. Binn's material from Port Ludlow, 

 Washington; C. limosa^ in the variety stygia^ Bailey; G.fili- 

 formis^ var. latifoUa^ in the Vancouver plant, and Hall's No. 

 607 from Oregon, Suksdorf's No. 51 from Klikitat Co., Wash- 

 ington, and Greyer's No. 72 from Oregon ; and C. rostrata^ in 

 the Vancouver plant, and Piper's No. 991 from Seattle, and 

 Suksdorf's Nos. 55 and 56 from the Cascade Mts. of Wash- 

 ington. The same tendency has likewise been noted in 

 Eleocharis and Jimcus. Without attempting here a discus- 

 sion of the conditions which tend to produce upon our north- 

 west coast the darkening of scales or.other chartaceous portions 

 of plants, it may be suggested that the brown color ordinarily 

 seen in the Canoe Birch of Vancouver and the coastal region 

 of Washington and British Columbia is perhaps due to the 

 same physiological cause. 



Emphasis has likewise been laidf upon the great height of 

 this northwestern tree as compared with the eastern JBetula 

 alba (^papyrifera^. Yet it is interesting to note that David 

 Lyall (whose specimens from the Lower Frazer River are a 

 close match for Hooker's original description and for the trac- 

 ing of the Scouler specimen) specially commented upon the 

 tree as "growing to the height of 60 or 70 feet,":}: while 

 Piper's Whitman County trees are much lower. Since the 

 brown-barked Betula occidentalis differs, then, only in this 

 somewhat inconstant color of the bark from the ordinarily 

 pale-barked B. alba, and since it is often no taller than the 

 eastern tree, it seems to the writer hardly worthy special 

 recognition, and that the tree was well treated by Professor 

 Sargent in the Silva as a local tendency of the white-barked 

 tree. 



Betula alba, var. glutinosa. 



Besides the ordinary Canoe Birch and its brown-barked form 

 of the Pacific slope, there are many tendencies of Betula alba 

 in America which deserve special comment. A single tree 



* See, for example, Boott, 111. ii, 98, etc. ; Holm, this Journal, 4th series, 

 ii, 218 ; Fernald, Proc. Am. Acad., xxxvii, 500, 504. 



t Sargent, Silva, 1. c, Bot. Gaz., 1. c. % Lyall, Jour. Linn. Soc, vii, 134. 



