EEPRODUCTION IN PLANTS 



81 



on their inner surface. Tell what you have 

 done, and state whether the openings in the 

 yellow anthers from which the pollen is dis- 

 charged are found on the inner surface (next 

 the pistil) or on the outer surface of the anther. 



C. Pistil. 



1. Examine the pistil after the stamens have been re- 



moved. Carefully describe the three parts 

 (ovary, style, and stigma) of which it is com- 

 posed. 



2. Observe a tiny cavity on the tip of the stigma. The 



inside of this cavity is the real stigma or stig- 

 matic surface. Describe the shape and state 

 the situation of the stigmatic surface. 



D. Cross-pollination of the pansy by bumblebees. 



1. Hold a pansy in its natural position. 



a. State the situation of the stamens with reference 



to the odd petal (i.e. are they above or below 

 this petal?). 



b. On what, therefore, will pollen probably fall if it 



is shaken out of the anthers ? 



2. To determine whether or not what you have just 



stated is true, thrust a slender tooth-pick under 



the stigma and then under 



the stamens and into the 



spur. Shake the flower 



gently and then withdraw 



the tooth-pick and examine 



the surface with a hand 



magnifier. Tell what you 



have done and state whether 



or not pollen is found on 



the tooth-pick. 



3. Examine a bumblebee. On what 



part of the insect (i.e. 

 mouth-parts, head, or body) 

 would the pollen be most 

 likely to fall when the bee 



FIG. 30. Head of a 

 bee. 



