BIRCH FAMILY 



tial oil identical with that obtained from Gaultheria pro- 

 cumbens, and which under the name of Wintergreen Oil is 

 employed as a remedy for rheumatism. The -remedial 

 agent is salicylic acid, of which it contains a large percen- 

 tage. 



The wood when first cut has a beautiful rosy tmge which 

 deepens with age and exposure. The difference between the 

 annual circles gives it a general clouded appearance and this 

 is especially marked in a section taken from the point of 

 union of a large limb with the body of the tree. When such 

 a piece is skilfully stained and polished, it closely resembles 

 mahogany. As a matter of fact, all good imitations of ma- 

 hogany are birch. However, the wood is beautiful enough 

 to have a value of its own. 



ALDER 



Alnus glutin6sa. 



The northern native alders east of the Rocky Mountains 

 are shrubs, following the water-courses and nowhere attain- 

 ing the arborescent form. They are aquatic, enjoying situa- 

 tions too wet for either willow or poplar. 



The only alder tree which is commonly found in the northern 

 states is Alnus glutinosa, a European species which is fairly 

 naturalized. It is native to the entire continent of Europe 

 and although naturally aquatic will grow in good soil, some- 

 what removed from water. 



The leaves are orbicular, obtuse, wedge-shaped at base 

 and serrated at margin. When young the leaves and stems 

 are somewhat glutinous, whence the specific name. The 

 bark is dark and furrowed, and the wood is valuable for but 

 one purpose. It will not endure alternate wet and dry, but if 

 constantly submerged it becomes extremely hard and virtu- 

 ally incorruptible. 



The flowers are monoecious, the staminate blossoms are long 

 drooping catkins which form in the late summer and hang 



314 



