274 TREES OF MINNESOTA. 



and led to the impression that it is not so hardy as the Cotton- 

 wood. The foliage seems to resist the attacks of the leaf fungus 

 better than the Cottonwood. 



BETULACEAE. BIRCH FAMILY, 



Genus BETUI/A. 



Flowers monoecious, apetalous, appearing before or with the 

 leaves; the staminate in long pendulous catkins; stamens two; 

 the pistillate in erect cylindrical catkins; ovary naked, two- 

 celled. Fruit a small nut, surrounded by a wing and covered 

 by the enlarged scale of the catkin, ripening in autumn. Leaves 

 alternate, simple, dentate or serrate. Trees or shrubs with 

 watery juice. A large genus represented by many species. 

 The bark contains a resinous balsamic oil sometimes used in 

 tanning leather. In parts of this country and Canada the bark 

 and leaves of various birches are esteemed as domestic reme- 

 dies for diseases of the skin, for rheumatism and gout. An oil 

 obtained from the inner bark by distillation is also used ex- 

 ternally for the same purpose. The sweet sap of many species 

 is used as a beverage, and is sometimes made into wine. 



Propagation. By seeds, which should be sown when gathered 

 or stratified over winter and sown in the spring and the seed- 

 lings given some shade during the first season. The varieties 

 are propagated by budding, grafting and inarching on the parent 

 species. 



Betula papyrifera. Paper Birch. Canoe Birch. White 

 Birch. 



Leaves ovate or heart-shaped, dark green on the upper side. 

 The bark is reddish on the twigs under four or five years old 

 and white on the older branches and trunk, and readily sep- 

 arated into papery sheets. A good sized tree, frequently sixty 

 or seventy feet high, with a trunk from two to three feet in 

 diameter, or perhaps in severe locations dwarfted to a mere 

 shrub. 



Distribution. Throughout Canada to Arctic Ocean ("Widest 

 range of any Canadian tree"), south to northern Pennsylvania, 



