Human Factor in Plant Evolution 285 



the enormously long period during which these have 

 been under cultivation, they have lost most of their 

 original characters, and it is almost impossible to 

 determine what their progenitors were, and whether 

 they still exist in the wild state. It has been argued 

 from the rapidity with which plants are known 

 to change under cultivation, that the ancestors of 

 some of the cultivated grains may still exist in the 

 wild state, but so different from their cultivated de- 

 scendants as not to be recognizable. The most 

 important of these grains are wheat, rice, and 

 maize. 



There is much doubt as to the origin of the dif- 

 ferent cultivated forms of wheat, and it is still a 

 question whether they really all belong to a single 

 species. Probably they were derived from some 

 species inhabiting the region of the Euphrates, and 

 perhaps also parts of Southeastern Europe, but just 

 exactly what these species were, is by no means 

 clear. Rice has been cultivated from the earliest 

 historic times in India and China, and wild rice ap- 

 parently specifically identical with the cultivated 

 plant still grows in India. It might be said here 

 that the " wild rice " of the Eastern United States, 

 which was so important an article of food among 

 certain of the North American Indians, is an en- 

 tirely different plant from the Oriental rice. Maize, 

 the staple grain of the New World, has been culti- 

 vated from the earliest times of which there are any 

 records, both in Mexico and South America. It is 



