436 STRUCTURE AND LIFE HISTORIES 



Each stamen consists of a slender stalk, the filament, 

 bearing at its tip two microsporangia {pollen-sacs) , 

 united to form the anther. In the pollen-sacs are numer- 

 ous microspores, which finally develop into pollen- 

 grains. 



Fig. 323. — Wood lily {Lilium philadelphicum). 



A central organ, the pistil, composed of three mega- 

 sporophylls (carpels) united, and enclosing the mega- 

 sporangia (ovules). All the pistils taken together (one or 

 more) constitute the gynoccimn. 



The pistil consists of three distinct regions as follows: 



(a) The enlarged basal part, enclosing the ovules, 

 and hence called the ovary. 



(b) A slender upward prolongation of the ovary, 



