(Explanatory notes referring to the illustrations on the other side of this sheet.) 



Common Alder, (Alnus serrulata) 



Near the ends of the twigs are the staminate catkins, tightly closed, and the 

 much smaller immature fertile catkins; both groups awaiting the coming of spring 

 before opening. Lower on the stem are the remains of the fertile catkins of the 

 preceding year, which have shed their seeds. 



Seaside Alder, {Alnus maritima) 



Each of the two twigs at the left bears one small fertile catkin, recently fei'til- 

 ized. The staminate catkins, foi'merly attached to the extreme ends of these 

 twigs, have shed their pollen and fallen off. The middle twig bears last season's 

 fertile catkins, now nearly mature. On the right are shown catkins which matured 

 and shed their seeds the previous season. 



