[Chap. XXXIII SEXUAL REPRODUCTION IN FLOWERING PLANTS 373 







D ■■'1/^^-- 



Fig. 165. Formation of microspores and pollen in the anther. A, cross section 

 of a young anther with four microsporangia containing microspore mother cells; 

 B, an enlarged cross section of one microsporangium containing cells in groups of 

 two formed by division of the microspore mother cells; C, a slightly older stage 

 in which further cell division has resulted in microspores adhering in groups of 

 four; D, the microspores have separated and some of them have become pollen 

 grains. Two of the microsporangia have become one pollen sac, which has split 

 open along one side. 



at this point, and return to it after we have found out what is occurring 

 in the pistil. 



What takes place in the pistil? The externally visible parts of a pistil 

 are the stigma, style, and ovulary. If a young ovularv is broken in two or 

 dissected, it will be seen to contain one or more small roundish bodies 

 known as ovules. 



