36 



on the two-rowed sides, and always stand erect, even Avhen ripe, but 

 break in pieces easily. The spikelets are flat on the inner side, or 

 form a concave surface with the projecting edges of the outer chaff. 

 They are arranged very compactly in the head and are usually one- 

 grained, except in the variety Engrain double (Plate VII), where 

 they possess two grains. The outer chaff is deeply boat-shaped and 

 rather sharply keeled, the keel terminating in a stiff* tooth. The 

 grains, which are tightl}' inclosed in the spikelet, are light red and 

 extremeh' flattened, becoming thus bluntly two-edged and possessing 

 an exceedingly narrow furrow. 



This species is at present but little improved over the original wild 

 form, and only a few varieties have been developed. Nevertheless 

 some of the most valuable qualities maj^ be expected from these varie- 

 ties if they can be successfully employed in hyl)ridization experiments. 

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

 fertility, and in the writer's experience are absolutel}^ proof against 

 orange leaf rust. Einkorn is entirely unknown in this country, except 

 among a few experimenters, but is grown to a limited extent in Spain, 

 France, Germany, Switzerland, and Italy. The two chief varieties 

 are common Einkorn and Engrain double. 



The valuable qualities to be obtained in this species may be summa- 

 rized as follows: 



( 1 ) Power of holding the grain in the head. 



(2) Resistance to orange leaf rust. 



(3) Hardiness. 



(4) Resistance to drought. 



(5) Stiffness of straw. 



An undesirable quality is: 



(1) Brittleness of the head. 



GEOGRAPHIC GROUPS OF WHEATS. 



From the description of the different natural groups just given and 

 the statements concerning their geographic distribution, it may be 

 inferred that the localities as well as the natural groups might also 

 be given from which particular qualities in wheat can be obtained. 

 This can be done, but not with the completeness that could be desired, 

 as it is not yet accurately known what kinds of wheat grow in all 

 regions of the world. However, the matter may be stated approxi- 

 mately and briefly as follows: (1) White Avheats containing much 

 starch are grown in the Paciflc Coast and Kocky Mountain States of 

 this country, in Chile, in Turkestan, and to some extent in Australia 

 and India. (2) Amber or reddish-grained wheats, also starchy, are to 

 be found chiefly in the Eastern States of this country, in western and 

 northern Europe, and to some extent in India, Japan, and Australia. 

 ( 3 ) Large proportions of gluten content of the quality considered to 



