314 FIELD CROPS FOR THE COTTON-BELT 



only when grown under the same climatic conditions and 

 allowed to mature fully. Any condition that interrupts 

 maturation will result in a higher percentage of protein 

 in the crop, especially the grain, due to the relatively 

 low starch formation under such conditions. Large, 

 plump kernels produced under favorable conditions usually 

 contain a lower percentage of protein than small, shriveled 

 kernels produced under unfavorable conditions. 



TYPES AND VARIETIES OF WHEAT 



Wheat varieties are most often classified on the basis 

 of those differences induced by environment rather than 

 on the basis of botanical differences. However, wheat 

 types present botanical relationships of sufficient impor- 

 tance to merit consideration. 



384. Botanical classification of wheat types. — There 

 are eight principal types of cultivated wheat. Of these 

 eight typesy six are closely related and will therefore cross 

 readily with each other. The classification here given is 

 the one made by Hackel, and is taken from Hunt's " Ce- 

 reals in America:" 



Tpiticura 



sativum 



lenax 



monococcum (1) einkom 

 spelta (2) spelt 

 dicoccum (3) emmer 



vulgare (4) common wheat 

 compactum (5) club or square-head wheat 

 turgidum (6) poulard wheat 

 durum (7) durum wheat 

 polonicum (8) Polish wheat 



All of the subspecies of Triticum sativum cross readily 

 with each other. Hunt states that "Einkorn never and 

 Polish wheat rarely, gives rise to a fertile cross with com- 

 mon wheat." 



