PLANT BREEDING 



429 



be perpetuated with certainty by planting tubers of the new 

 variety. But if a hybrid bean, pea, or M'heat plant is produced, 

 only a few of its seeds will " come true to seed " ; that is, the 

 offspring of the hybrid seeds will, many of them, be what 

 breeders call " rogues," or undesirable varieties, not closely 

 resembling their hybrid parent. Year after year, for several 

 generations, the garden plots containing descendants of the 

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



Fig. 340. Variation in wheat, tlie hybrid offspring of hybrid parents 



After figure redrawn from Transaction/: of the Highland and Agricultural 

 Society of Scotland 



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." 

 393. Results of hybridizing the grains. In this country 

 especial attention has been given to hybridizmg Indian corn 

 and wheat. Some valuable varieties of corn have akeady 

 thus been obtained, and many more seem likely to be secured. 

 Hybrid wheats are of importance for use as stocks from which 

 to breed and select. At the agricultural experiment stations 

 of the great wheat-growing states much time is now spent in 

 hybridizing wheats for breeding purposes. 



