WHEAT 67 



They are among the hardiest of all cereals and seem to be 

 constant in fertility, and in the author's experience, are 

 proof against orange leaf-rust. Einkorn is entirely un- 

 known in this country, except among a few experimenters, 

 but is grown to a limited extent in Spain, France, Ger- 

 many, Switzerland, and Italy. 



61. Subdivisions and varieties of einkorn. There 

 are apparently only four cultivated varieties of einkorn 

 yet known, classified as follows : 



(TRITICUM MONOCOCCUM HORNEMANNI, CLEM.) 



1. Chaff red, with short hairs. 



Winter Red Chaff. 



(TRITICUM MONOCOCCUM LVETISSIMUM, KCKE.) 



2. Chaff glabrous, yellow. 



Yellow Chaff. 



(TRITICUM MONOCOCCUM VULGARE, KCKE.) 



3. Glabrous red chaff. 



Spring or Winter Common Einkorn. 



(TRITICUM MONOCOCCUM FLAVESCENS, KCKE.) 



4. Chaff glabrous, faint yellow. 



Spring Double Einkorn. 



62. Distribution of wheat in the United States and 

 Canada. Upon the basis of our knowledge to date of 

 the conditions of wheat environment and adaptation of 

 varieties, the United States and the grain-growing por- 

 tion of Canada may be considered as divided roughly into 

 ten wheat districts, each possessing characteristics more 

 or less different from those of the others. In fact, in some 



