PLANT BREEDING 



319 



generations, the garden-plots containing descendants of 

 the new hybrid must be rogued, or gone over plant by 

 plant, in order to destroy all individuals but those of the 

 desired variety. In the case of wheat, after the fourth 

 generation some plants are usually to be found that will 

 "come true to seed." 



398. Results of Hybridizing the Grains. — In this coun- 

 try especial attention has been given to hybridizing In- 

 dian corn and wheat. Some valuable varieties of corn have 

 already thus been obtained and many more seem likely to 



Fig. 223. 



a, a stoneless wild plum ; 6, c, d, fruit ol hybrids of a with the French 

 prune. (All drawn to the same scale.) 



be secured. Hybrid wheats are of importance for use as 

 stocks from which to breed and select. Much time is now 

 spent at the agricultural experiment stations of the great 

 wheat-growing states in hybridizing wheats for breeding 

 purposes. 



399. Results of Hybridizing Small Fruits. — The most 

 familiar hybrids among small fruits are grapes. Very 

 likely the Delaware and the Catawba are hybrids, and the 

 Salem, Brighton, and Diamond certainly are. Many varie- 

 ties are directly or remotely descended from hybrids be- 

 tween the European wine grape and our northern fox 

 grape, two wholly distinct species. 



