DICOTTLEDONES. 



193 



8. Salicaceae. The Willow family comprises dicecioua 

 trees and shrubs whose amentaceous flowers are destitute 

 of a perianth. There are two genera and one hundred and 

 ieighty species, found principally in the North Temperate 

 and Arctic Zones. Many species of Willow (Scdix) are 

 cultivated for basket-making. The charcoal obtained from 

 them by charring the wood is extensively used in the 

 manufacture of gunpowder. The Weeping Willow (S. 

 Babylonica) is a native of Persia, but common in cultiva- 

 tion. The Poplars (Fopulus) have a light, white wood, 

 used much in manufacturing. The Lombardy Poplar (P. 

 dilaiata) is the commonest one cultivated for ornament. 



9. Platanacese. The Plane-tree family consists of 

 five monoecious plants of the genus Plakbnus, whose flowers 

 are in globose catkins. The Plane-tree, or Sycamore (P. 

 ocoidentalis), whose wood, though valuable, is not much 

 used, is found in the 

 Eastern United States ; 

 one species occurs in 

 California, two in Mex- 

 ico, and the fifth (P. 

 orimtalis) is found in 

 the Old World. 



10. Betulaceae. 

 Birch family. Of these 



■ monoecious, amentace- 

 ous trees, numbering 

 over forty species, the 

 most useful perhaps is 

 the White Birch (Betula alha). of Northern Europe, Asia, 

 and North America. Its wood is used for fuel, also in 



Fig. 303. Euphorbia marginatum 



13 



