114 



PAPER BIRCH. 



Betula alba var. papyrifera, (Marshall) Spach. 



FORM A large tree usually attaining a height of 50-75 ft. with a diameter of 1-2 ft., but 

 may roach a height of 80 ft. with a diameter of 3 feet. Trunk in open grown trees short and 

 covered nearly to the base with lateral, often ascending branches; in close stands branchless 

 below and bearing a narrow open head. 



BARK On trunk and older branches chalky to creamy white and peeling off in thin film- 

 like layers which are tinged with yellow and covered with horizontally-elongated lenticels. 

 On older trunks rough and often fissured into irregular thick scales. 



TWIGS Rather stout, somewhat viscid, decidedly hairy, at first greenish, later becoming 

 smooth, reddish-brown, and" after several years, bright white, like the trunk, covered with 

 pale, horizontally-elongated, orange-colored lenticels. 



BUDS Alternate, ovate, sharp-pointed, divergent, about 1 of an inch long, dark chestnut- 

 brown in color, covered by a few overlapping bud-scales with downy margins. 



LEAVES Alternate, simple, ovate, 2-3 inches long, 15-2 inches wide, rather firm in texture; 

 upper surface dark green, under surface light green; narrowed or rounded at the base, 

 sharply toothed on the margin and sharp-pointed at the apex. 



LEAF-SCARS See "Leaf -Scars" under Black Birch, page 118. 



FLOV7ERS Appear in April or May before the leaves. The staminate are arranged in 

 aments, which occur in groups of 2-3 and are about J to 1$ inches long, becoming 3J-4 

 inches long in spring. The pistillate have light green lanceolate scales and bright red 

 styles, and are arranged in clusters about 1-11 inches long. 



FRUIT A cylindrical, short-stalked strobile about 13 inches long. Scales long, with 

 thick lateral lobes and a rather long terminal lobe. Seeds small and winged. Wings wider 

 than the nut. 



WOOD Diffuse-porous; rays small and inconspicuous; light, strong, hard, light brown tinged 

 with red, with rather thick, light sapwood. Weighs 37.11 Ibs. per cubic foot. Used exten- 

 sively for spools, shoe lasts, pegs, fuel, and in the manufacture of paper^pulp. 



DISTINGUISHING CHARACTERISTICS The Paper Birch, also known as Canoe Birch and 

 White Birch, may readily be distinguished from all the other species of Birch in Pennsyl- 

 vania except the Gray Birch, by its characteristic white bark, which is never renewed when 

 once removed. The European White Birch, which is introduced extensively for ornamental pur- 

 poses, also has a white bark. To distinguish it from the Gray Birch see "Distinguishing 

 Characteristics" under Gray Birch. 



RANGE From Newfoundland to Alaska, south to Penrsyivania, Michigan, Colorado, and 

 Washington. This is one of the few transcontinental species. 



DISTRIBUTION IN PENNSYLVANIA Found only in the northern part of the State. Com- 

 mon but scattered in Tioga and adjoining ccunties. 



HABITAT Usually found on rich wooded slopes and on the borders of lakes, swamps, and 

 streams; also scattered through the forests of other hardwoods and occasionally through 

 coniferous forests. 



IMPORTANCE OF THE SPECIES This species is commercially of little importance in 

 Pennsylvania on account of its limited distribution. It is not of sufficient importance to 

 justify its artificial propagation, but wherever it occurs naturally it should be protected 

 so as to insure an abundant future growth. The wood is sufficiently prized to justify its 

 conservative utilization, and also its protection, where nature produces it gratuitously. 



