Handbook of Trees of the Xoetiiekn States and Canada. 121 



The Paper Birch, west of the Rocky Moun- 

 tains, is said to attain a hoi<,'ht of 120 ft. with 

 trunk from 3-4 ft. in thickness, but clsewliere 

 rarely exceeds 70 or 80 ft. in lieight. Wlicn 

 isolated from other trees it develops a full 

 rounded and usually irregular top of many 

 branches. The bark of the larger branches 

 and young trunks is laminate, smooth and of 

 creamy or ivory whiteness, marked with long 

 horizontal raised lenticels. As the trunk en- 

 larges the bark becomes more or less streaked 

 and blotched with blackish and the outer layers 

 separate and roll back in large ragged sheets. 

 On very old trunks the bark at base becomes 

 broken into large closely appressed irregular 

 scales. It inhabits rich slopes and ornaments 

 the banks of northern streams and lake-shores 

 from the Atlantic to the Pacific, ranging north- 

 ward to the Arctic Circle. With the northern 

 Indians its bark, impervious to water, is an 

 indispensable material for the manufacture of 

 their canoes and for many articles for domestic 

 use. 



The wood, of which a cubic foot when abso- 

 lutely dry weighs 37.11 lbs., is used in the 

 manufacture of wooden-ware, wood-pulp, etc., 

 and is excellent for fuel. 2 



Leaves ovate, 2-4 in. long, acute or acuminate 

 at apex, rounded or obtuse (cordate in var. cordi- 

 folia Fern. ) and entire at base, doubly or ir- 

 regularly serrate, tlaick and firm at maturity, 

 glabrous dark green al)ove, paler and pubescent on 

 the vein.s and with black glands beneath. Floircrs: 

 staminate aments %-l''/i in. lona; in winter, finally 

 .3-4 in. long: pistillate aments 1-1 V2 in. long, 

 slender, with light green scales and red styles. 

 Fruit: strobiles cylindrical, about 1 V2 in. long, 

 drooping, glabrous, middle lolie of scales longer 

 than broad ; nutlet much narrower than its wings. 



1. Syn. B. papyracea Alt. 



2. A. W.. II, 4;^. 



