THE ABELE. 



Po'pulus aVba L. 



The two genera Populus, the Poplars, and Sal'ix, the 

 Willows, constitute the Natural Order Salic'acece, 

 a group of catkin-bearing trees and shrubs not 

 very obTiously allied to any others. Though vary- 

 ing greatly in dimensions, all of them are perennial 

 woody plants, generally of rapid growth, and pro- 

 ducing a soft white wood. Their leaves are deciduous 

 and undivided, spring singly from the nodes, and are 

 furnished with stipules ; and their flowers are in con- 

 spicuous catkins, the two sexes being on different 

 plants (" dioecious "). This introduces a double diffi- 

 culty into the study of- the group, for not only do 

 the staminate and carpellate trees of one species 

 sometimes differ to some extent from one another, but 

 hybrids or cross-bred trees frequently occur in a 

 natural state, and still more frequently where, as in 

 withy-eyots, several kinds are cultivated side by side. 

 The flowers are of a very much simplified type, the 

 "perianth" — the calyx and corolla, that is, of an 

 ordinary flower — being replaced by simple minute 

 scales. These scales being single — i.e. there being 

 but one to each flower in the catkin — they are 

 probably really rather of the nature of bracts ; whilst 

 the perianth may be looked upon as altogether absent 

 in Willows, though perhaps represented by a little 

 one-sided, cup-shaped body, called a " disk," in the 



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