CHAPTER XXIX 
PLANT BREEDING 
388. Definition of Plant Breeding. — Plant breeding 
means the intentional production and perpetuation of new 
varieties of plants. As ascience it is not much more than 
fifty 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 afforded 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 found only 21 
of these worthy of further trial. Not 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 Candolle’s Origin of Cultivated Plants, Chapter I. 
309 
