160 GROWTH AND WORK OF PLANTS 



the walls of the pollen grains. Each pollen grain is strongly three- 

 angled, the angles appearing as pronounced protuberances, each 

 one nearly as large as the central body. Germination of the 

 pollen grains takes place through these angles. 



253. The pistil of the evening primrose consists of three dis- 

 tinct parts, the ovary, the style, and the four stigmas. The ovary 



Fig. 117. 



Flowers of evening primrose, the two at left showing the way the petals are folded in the bud. 

 At the right, petals removed, showing anthers opening while the stigma lobes are still closed . 



is at first nearly cylindrical, but becomes four-angled with the 

 ripening of the seed. There are four locules in the ovary. This 

 indicates that it is composed of four parts which are united to 

 form a compound ovary. The ovules are numerous and occur 

 in two rows. The style is longer than the calyx tube and is well 

 shown in the dissection of the flower. The stigma consists of 



