LESSONS WITH PLANTS 



327 



simple cases of cross-pollination, such as the sweet pea, 

 the morning-glory, sweet clover, etc. Try this experiment : 

 Tie over a sweet pea bud or a red clover head a paper 

 or muslin bag. The flower 

 so treated will not form 

 seeds. In many flowers 

 there is provision, however, 

 for the pollen to come in 

 contact with the stigma of 

 the same flower. Self-pol- 

 lination thus takes place 

 and seeds will form. A 

 better experiment is this: 

 Select some flowers that 

 fiave pistillate and stami- 

 nate flowers separate, where 

 5elf-po]hnation is impossi- 

 ble. The squash, pumpkin 

 3r cucumber is very good 

 For this. Cover the pistil- 

 late flower so insects can- 

 lot get at the stigmas, and 

 10 seeds or fruit will form. 

 This will bring out well 

 ;he importance of the sta- 

 nens and pistil and also of the process of pollination. Re- 

 :er to the subject of cross-poUination as treated under In- 

 jects, page 224. 



In these grades also a simple study may be made of another 

 method of polHnation, namely, by the wind. Get the pen- 

 dulous catkins of cottonwood and butternut, the staminate 



Fig. 126. Pollination in Sweet Pea. 



