CHAPTER TWENTY-NINE 



PLANT BREEDING 



The origin of our most important cultivated plants is in most 

 instances shrouded in mystery, for they were brought into culti- 

 vation by prehistoric peoples. When Columbus discovered 

 America, the Indians of the New World were cultivating corn, 

 potatoes, cotton, kidney and lima beans, arrowroot, peppers, 

 peanuts, pineapples, tomatoes, tobacco, sweet potatoes, squash, 

 pumpkin, and a number of tropical food and fiber plants. The 

 other important food plants, like wheat, rice, barley, rye, and 

 oats, were mostly selected from wild species by the prehistoric 

 races of Asia and Africa. It is a singular fact that within historic 

 times no important additions have been made to the food plants 

 of the world except through borrowing from the so-called primi- 

 tive races. During historic times, however, these food plants 

 have been greatly modified and innumerable superior varieties 

 have been developed. Among plants that produce edible fruits, 

 berries, and nuts, some additional species have been brought into 

 cultivation during recent centuries — notably grapes, cran- 

 berries, raspberries, dewberries, cherries, plums, and pecans. 



Objectives in plant breeding. Plant breeding is concerned 

 with the improvement of economic plants, with the discovery of 

 new varieties, and with the production of new plants of economic 



A. B. Stout 



Fig. 170. An ear of white sweet corn partly pollinated by pollen from black Mexican sweet 

 corn. The color is in the endosperm (xeniophyte) and was produced by the factor for color 

 carried by the sperm nucleus which furnishes one of the three sets of chromosomes in the 

 endosperm nucleus. 



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