EXERCISE 31 



THE CORN FLOWER 



Fig. 33. Corn tassel and ear showing silk 



Statement. The flowers of the corn plant are arranged in clusters in two different parts of the plant. 

 The male flowers form in the tassel, while the female flowers form on the cob and are surrounded by 



the husks. The flowers in the tassel contain the pollen grains 

 which, when ripe, are liberated from pollen sacs. When a pollen 

 grain falls upon a corn silk it begins to grow, and the long, 

 slender thread which it puts forth reaches the base of the silk 

 and carries with it the cell which fertilizes the female cell within 

 the undeveloped kernel. This fertilized cell grows and becomes 

 the embryo corn plant and the kernel then develops to maturity 

 and is ready to reproduce its kind. 



Object. To observe how the corn flower is pollinated, where 

 the pollen forms, and how it is distributed. 



Materials. Ears of mature corn ; a microscope ; corn tas- 

 sels and ear shoots which were preserved in formalin just as the 

 flowers were opening, or fresh flowers if available. 



Directions. Examine ear shoots and mature ears, noticing 

 where the silks are attached. Examine the tassel of the corn 

 plant and observe how the pollen sacs are attached to the 



tassel. Examine a pollen sac under the microscope and make 



a drawing to show its shape. Show in the drawing where the 



ripe pollen escapes from the sac. Examine the surface of 



a pollen grain under the microscope. Describe it. Observe 



whether the pollen grains and silks of a stalk of corn ripen at 



the same time or whether the silks of one plant are, as a rule, 



pollinated by the pollen from neighboring plants. In other 



words, observe whether the corn is self- or cross-pollinated. 



Observe the nature of the surface of the silks and how dust 



or pollen grains stick once they come in contact with the silks. 



Explain the significance of this. 



Notice the amount of pollen a corn plant produces. Ob- 

 serve the ground, the plants, and your clothing when walking 



through a field of corn that is in full bloom. Does there seem 



to be a scarcity of pollen ? 



Questions. What does a pollen grain do after reaching the 

 silks ? Is there an excess of pollen produced ? What happens if pollen from one kind of corn fertilizes 

 the female cell of another kind of corn ? Is corn inbred or crossbred ? When two varieties of corn are 

 planted side by side will the crop from each be pure and true to the seed planted ? Explain fully what 

 will happen and how it is brought about. How far may corn pollen be carried by the wind ? In growing 

 pure seed corn what precautions should one take ? Are the same precautions necessary in growing pure 

 seed of other farm crops and why ? 



Fig. 34. Results of poor pollination 



When scanty pollination occurs, few ovules are 

 fertilized and few kernels develop. 



References. Waters, H. J. 

 Southern Field Crops, pp. 88-89. 

 Orange Judd Company. 



Essentials of Agriculture, p. 138. Ginn and Company. Duggar, J. F. 

 The Macmillan Company. Hunt, T. F. The Cereals in America, p. 185. 



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