1 44 MANUAL OP NATDRB STUDY. 



Studied, all the conditions favorable for the perfect 

 union of male element with female element, or fer- 

 tilization. 



In Indian corn what is the style called ? Where 

 are the stamens and what are they called? Why 

 do not full ears of corn grow upon isolated stalks ? 

 Examine a few ears from solitary stalks and see if 

 the required number of grains is developed. From 

 your observation what conclusion can be formed as 

 to the provision of the corn plant for self-fertiliza- 

 tion? How are the styles, "or silks," of the corn 

 protected from the reception of its own pollen? 

 Examine a stalk of corn so as to be sure that one 

 or more of the blades pass between the tassel and 

 the silk, thus acting as a roof to ward off the pollen. 

 These blades may also serve to keep off too much 

 water from the stigma, or too much hot sunshine, 

 either of which would destroy the function of the 

 stigma, but it keeps off the pollen as well. How 

 are the chances of fertilization improved by com- 

 munity plant life? How is the ragweed benefited 

 by community life ? Let the pupils examine the 

 ragweed and locate the seed pod and also the pollen. 

 Be sure to observe that the pollen is dry and light, 

 and therefore easily carried by the winds. 



What other plants bear pollen that is light and 

 dry and easily carried by the wind ? We may call 

 such plants wind-fertilized plants. 



