214 BETULACE^E. [CLASS 



Trees. Flowers monoecious. Ovary 2-celled. 



Type Common Birch (Betula alba). 



A deciduous tree, with laminated white papery bark, 

 slender twigs, alternate simple leaves, and amentiform 

 inflorescence. 



N.B. Both the staminate and pistillate flowers are 

 arranged in short cylindrical catkins. The scales of the 

 fruit-catkins of Birch fall away from the axis of the 

 catkin, but in Alder (Alnus) they are woody and remain. 



This small Family includes but two genera, Birch and 

 Alder ; the former prevalent in high latitudes, penetrating 

 beyond the Arctic circle. 



The laminated bark of a Canadian species of Birch 

 (B. papyraced) is much used for household purposes, and 

 with the quills of the North American porcupine and 

 dyed hair of the mouse deer it is worked up into various 

 ornamental articles by Indian tribes. 



60. Natural Order Salicacese. The Willow Family. 



DISTRIBUTION. An Order of but two genera. Chiefly 

 confined to the north temperate zone of both hemi- 

 spheres ; especially affecting Alpine and Arctic regions. 

 British genera 2, species 18. 



Trees or shrubs. Flowers unisexual. Ovary I -celled, 

 ovules basal or parietal. 



Type Sallow Willow (Salix Caprea). 

 A low deciduous tree, with alternate simple stipulate 

 /eaves and dioecious amentaceous flowers. 



