PLANT PROPAGATION 



115 



127. The numbers of seeds produced by plants. A second fact 

 which is evident to all is that plants produce an enormous number 

 of seeds. Suppose we consider the case of a vigorous pea-vine. In 

 the course of a season it should produce at least 20 pods, each con- 

 taining at least 5 seeds. Hence, at the end of a single season, one 

 pea seed would, if conditions were favorable, have multiplied itself 

 100 times. If each one of these seeds were to be planted where it 



FIG. 52. Variations in the corn ears produced in a single field. (Courtesy 

 of Dr. E. M. East, Bussey Institution, Harvard University.) 



had plenty of moisture, light, food, air, and favorable temperature, 

 it likewise should give rise to 100 seeds, and so at the end of the 

 second season we ought to have 100 X 100, or 10,000 pea seeds, all 

 propagated from a single pea seed. Simple multiplication shows us 

 that at the end of five years a moderately prolific plant like the 

 garden pea would have given rise, had all conditions been favor- 

 able to 10,000,000,000 new seeds. Bergen has made a patient 

 count of the number of seeds produced by an average morning 

 glory plant, and finds it to be rather more than 3000; hence, 

 at the end of the fifth year, if such a rate of reproduction were 



