IV. 



WHEAT. 



I. BOTANICAL RELATIONS. 



76. The Wheat Genus {Tritiaim L.). — The p'ants of this 

 genus are all annuals. The commonly cultivated species have 

 apparently been so changed from the wild type as to be depend- 

 ent upon man's agency for their existence. Sir John Lawes 

 was wont to say that if man should disappear from the earth 

 w^heat would follow him in three years. This is true, also, of 

 the common field bean, maize, tobacco, and a few other less 

 commonly grown species. 



Hackel divides the genus into two sections, viz., j!^gilops 

 L. and Sitopyros} In the former the glumes are flat or 

 rounded on the back, while in the latter they are distinctly 

 keeled. To the latter section belong the cultivated species. 



77. The Species of Wheat. — There are eight cultivated t}^pes 

 of wheat which are usually considered of greater value than the 

 variety type. Hackel recognizes but three true species and the 

 other t}^pes are treated as subspecies.^ 



The structural relationship is much closer between TV. 

 sativum and Tr. polonicum than between 7>. vioiiococciim and 

 either of the former. The pale a of Tr. monococctim falls into 

 two parts at maturity, while in the other two species the palea 

 remains entire. 7)'. sativum spelta and Tr. sat. dicoccum are 

 to be distinguished from the other four subspecies of sativum by 

 the grains remaining enclosed in the glumes upon threshing 

 and by the rachis breaking up at maturity. The common and 



1 In the following division into species and subspecies Hackel has been followed. 

 See The True Grasses. By Edward Hackel. Translated from Die Naturlichen 

 Pfianzenfamilien by F. Lamson-Scribrer and Effie A. Southworth, pp. 179-187. 



8 Ibid. 



