33 6 



THE WHEAT PLANT 



north-west of Anah on the right bank of the Euphrates " we found near 

 the camp, in a sort of ravine, wheat, barley, and Spelt, which we had 

 already seen many times in Mesopotamia." 



From the context these cereals were presumably uncultivated. Since 

 specimens have not been preserved, it is not possible to identify the wheat 

 and " Spelt " to which Olivier refers ; it is, however, highly probable 

 that the " Spelt " was the fragile-eared Wild Emmer ( T. dicoccoides) found 

 at the present day widely distributed throughout Asia Minor as far as 

 the western borders of Persia. 



Beijerinck, Hausknecht, and others held the view that all the races 

 of cultivated wheat were derived from the single wild ancestor T. aegilo- 

 poides, and in the early half of last century Fabre concluded that Aegilops 

 ovata was the prototype (see p. 342). The majority of botanists, 

 however, who have studied the problem agree that the wheats are poly- 

 phyletic, and that at least two species are concerned in their origin. They 

 are also in accord regarding the main outlines of the relationship of the 

 chief races to each other and to the two wild species T. aegilopoides and 

 T. dicoccoides. 



Schulz arranged the wheats in three separate series, the constitution 

 and relationship of which are indicated in the following table : 



Flaksberger's scheme of relationship given on p. 337 also divides the 

 wheats into three similar series or " conspecies," each with its corre- 

 sponding prototype. 



Vavilov discovered that T. monococcum is quite immune to Puccinia 

 triticina, Eriks., and resistant to Erysiphe graminis, D.C. He also found 

 that T. durum, T. polonicum, and T. turgidum constitute a group resistant 

 to these fungi, while T. Spelta, T. vulgare, and T. compactum are all 

 susceptible. 



