CHAPTER XXIX 

 PLANT BREEDING 



388. Definition of Plant Breeding. — Plant breeding 

 means the intentional production and perpetuation of new 

 varieties of plants. As a science it is not much more than 

 fiftj' years old. But some plants have been cultivated for 

 over forty-five centuries/ and during all that time atten- 

 tion has been paid to choosing and keeping up desirable 

 varieties of plants. 



389. Selection of. Spontaneous Varieties. — As has al- 

 ready been suggested (Sect. 254), plants in a state of nature 

 produce many varieties by ordinary variation, and they may 

 occasionally produce new species by mutation. 



Only a very few of all the multitude of spontaneous 

 variations among plants are likely to be valuable to man. 

 An example of this is aiforded by the results obtained by 

 the discoverer of the Concord grape. This familiar grape 

 was a seedling from a rather promising wild variety. The 

 grower of the Concord mother vine raised more than 

 22,000 seedlings from Concord seeds and formd only 21 

 of these worthy of further trial. Xot one of these seed- 

 lings is now a well-known grape. 



Cultivated plants for some reason, perhaps especially 

 because they are highly fed and stimulated to unusually 

 vigorous growth, vary more than wild individuals. Any 



1 See De CandoUe's Origin of Cultivated Plants, Chapter I. 

 309 



