SYLVICULTURAL NOTES ON BIRCH. 267 



Of fungi Nectria ditissima may cause cancerous forma- 

 tions, and Polyporus sulphureus red-rot in the stem. 

 Exoascus borealis causes witch's broom, and several 

 other species of this genus are found on the leaves and 



flowers. 



\ 

 9. BIECH Betula alia (L.). 



a. Utility. 



The timber is fairly heavy, specific gravity of air- 

 dried wood = -64, moderately hard, does not split well, of 

 small durability ; good firewood, which is also converted 

 into charcoal for the manufacture of gunpowder. The 

 timber is used by joiners, wheelwrights, coarse carvings ; 

 in Britain extensively used for bobbins, also for herring 

 barrels. The branches and still more young shoots and 

 trees are used for withes, brooms, &c. The bark is used 

 for tanning and the manufacture of small vessels and 

 boxes. 



b. Distribution. 



It is chiefly found in Northern and Eastern Europe ; 

 also in Northern Asia and in North America (a variety). 

 In Europe between 47 and 70 latitude. It is in- 

 digenous in Great Britain and Ireland. It is a tree of 

 the lowlands, lower hills, and even mountains. It 

 grows up to 2,500 feet in Scotland, in the Alps to over 

 5,000 feet. 



c. Locality. 



Climate. It requires but a low temperature, is frost- 

 hardy, and not particular as regards heat. It is highly 

 light- demanding, almost as much as Larch. It likes 

 moist air. Thrown to some extent by storms. Suffers 



