LESSONS WITH PLANTS 



327 



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

 the morning-glor)', sweet clover, etc. Try tliis exijcriment: 

 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- 

 hnation thus takes place 

 and seeds will form. A 

 better experiment is this: 

 Select some flowers that 

 have pistillate and stami- 

 nate flowers separate, where 

 self-pollination is impossi- 

 ble. The squash, pumpkin 

 or cucumber is very good 

 for this. Cover the pistil- 

 late flower so insects can- 

 not get at the stigmas, and 

 no seeds or fruit wiU form. 

 This will bring out well 

 the importance of the sta- 

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

 fer to the subject of cross-pollination as treated under In- 

 sects, page 224. 



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

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

 dulous catkins of cottonwood and butternut, the staminate 



Fig. 136. PullinLition in Sweet Tea. 



