DICOTTLEDONES. 



193 



8. Salicacese. The Willow family comprises dioBcious 

 trees and shrubs whose amentaceous flowers are destitute 

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

 eighty species, found principally in the North Temperate 

 and Arctic Zones. Many species of Willow (Salix) 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. 

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

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

 used much in manufacturing. The Lombardy Poplar (P. 

 dUatata) is the commonest one cultivated for ornament. 



9. Platanaceae. The Plane-tree family consists of 

 five monoecious plants of the genus Plaianus, whose flowers 

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

 OGeidentalis), 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. 

 orientalis) 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 alba) of Northern Europe, Asia, 

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



Fig. 303, Euphorbia marginata. 



13 



