280 



COMMON TREES AND SHRUBS 



If these are traced they will be found to spring from long 

 roots of the parent tree which grow horizontally just below 

 the surface, the main roots being deep in the soil. Such 

 shoots are called suckers, and they afford a means of vege- 

 tative propagation. In the late summer or early autumn 

 the ground near Poplar trees is often strewn with leafy 



Fig. 186. Black Poplar. i, leafy shoot ; 

 branch-scars ; 3, male catkin ; 4, male flower ; 

 6, female flower ; b.s, branch-scars ; d, cup-like disk ; s.s, bud- 

 scale scars. 



2, twig with two 

 5, female catkin ; 



shoots, varying in length from one to six feet. These are 

 deciduous shoots cut off by a separation-layer, as in the 

 leaves (Fig. 186, 2 b.s). Compare this with what occurs 

 in the Pine. 



The flowers are in catkins and, as in the Willows, are 

 dioecious, but have no nectaries and secrete no honey. 

 They appear before the leaves. The male catkin (3) is lax, 

 pendulous, and about two inches long. The bracts are 



