256 



TLANT STRUCTURES 



temperate regions, for here belong the oak (Fig. 238), hick- 

 ory, wahmt, cliestnut, beech, poplar, birch, elm (Figs. 198, 

 239), willow (Fig. 2-1:0), etc. The primitive character is in- 

 dicated not merely by the floral structures, but also by the 

 general anemophilous liabit. 



In the poj^lar (Populus) and its allied form, the willow 

 (Salix), the flowers are naked and liy})ogynous (Fig. lOG), 



Fig. 239. An elm in foliage. — From "Plant KeluLionB. 



