CHAPTER VI 



GRAMINEAE — Continued 



TRITICUM spp. 



WHEAT is grown in the temperate regions of every continent, 

 within the Arctic Circle, and in the highlands of Ecuador 

 and Colombia at the Equator. In the United States, it is a winter 

 or summer annual, being harvested in the southern states in June 

 and in the northern wheat areas in July and August. 



There has been much discussion as to the origin of wheat; and, 

 although some botanists maintain that all cultivated forms are 

 derived from a single wild ancestor, the majority, according to 

 Percival (lo), "agree that the wheats are polyphyletic, and that 

 at least two species are concerned in their origin. ' ' Several systems 

 of classification have been proposed for the numerous species, races, 

 and varieties which are recognized at the present time. Hackel (6) 

 has divided the genus into two sections, Aegilops and Sitopyros; 

 and the latter, which includes the cultivated wheats, into three 

 main species. The first of these is T. monococcum L., commonly 

 known as Einkorn or one-kerneled wheat, which is cultivated in 

 Spain and probably grows wild in Greece and Mesopotamia. The 

 second, T. sativum Lam., is the commonly cultivated wheat, which 

 he further subdivides into three principal races : T. spelta L., which 

 includes the ordinary spelt wheats; T. dicoccum Schr., emmer 

 wheat; and T. tenax. The last named has four subraces: T. vul- 

 gare Vill., common wheat; T. compactum Host., club wheat; 

 T. turgidum L., poulard wheat; and T. durum Desf., durum wheat. 

 The third main species is T. polonicum L., Polish wheat, which is 

 not a native of Poland, but occurs in Italy and Abyssinia and is 

 cultivated to some extent in North America. 



Percival recognizes two wild species, and classifies the cultivated 

 wheats in eleven natural groups or races of major rank. Of these, 

 the common bread wheat, Triticum vulgare, is the best known and 

 most generally used. This may be attributed to its physical 



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