216 TREES OF NORTH AMERICA 



rating freely into thin papery layers displaying in falling the bright orange-yellow inner 

 bark. 



Distribution. Banks of streams and lakes; southwestern British Columbia and north- 

 western Washington and eastward through eastern Washington and northern Idaho to 



Fig. 203 



northern Montana west of the continental divide; nowhere common and probably of its 

 largest size on the alluvial banks of the lower Fraser River, and on the islands of Puget 

 Sound. 



Betula papyrifera var. kenaica A. Henry. Red Birch. Black Birch. 

 Betula kenaica Evans. 



Leaves ovate, acute or acuminate, broadly cuneate or somewhat rounded at the entire 

 base, irregularly coarsely often doubly serrate, glabrous, dark dull green above, pale yel- 



Fig. 204 



low-green below, l'-2' long, l'-lf wide, with a slender yellow midrib and 5 pairs of thin 

 primary veins; petioles slender, f'-l' long. Flowers: staminate aments clustered, 1' long, 



