DICLINOUS FLO WEBS 



157 



177. The staminate catkin of one of the birches 

 is shown in Fig. 155. This is a drooping body, 

 and recalls the similar tassels of the poplars, 

 oaks, and hazels. In 

 this instance, however, 

 there is more than a 

 single flower beneath 

 each scale of the cat- 

 kin. In other words, 

 a catkin may be either 

 simple (comprising a 

 single flower at each 

 joint or under each^. 

 scale) or compound. 



177a. There are commonly 

 three beneath each external 

 scale in the birch, each flower 

 comprising two stamens, but 

 the anther loeules are separated 

 and the filaments divided so 

 as to imitate four stamens. 



These flowers are separately ^"'' ^^®' 



subtended by braetlets. Pistillate catkin of a birch. 



178. The pistillate catkin of another kind of 

 birch is shown in Fig. 156. It is a rigid or erect 

 structure, and, of course, persists until the seeds 

 are ripe, whereas the entire staminate catkin very 

 soon dies and falls. One of the three -parted bracts 

 or scales is removed and reversed at a. It sub- 



