48 HISTORY AND DISTEIBUTION OF SORGHUM. 



ductiveness, with other available ecologic characters, ought to be 

 included. 



Furthermore, the use of purely artificial keys must be given up and 

 natural groupings substituted before much permanent good can come 

 from any classification of cultivated varieties. The lumping of all 

 the forms which happen to have white seeds or spreading branches or 

 pendent panicles only adds to present confusion. It is necessary first 

 to define the major natural groups which agronomic and botanic 

 studies have shown to exist, even if such groups can not always be 

 sharply separated by a single character. When this has been done 

 the varieties in each group should be distinguished by the most ob- 

 vious natural characters. In this way only can we hope to prepare the 

 usable and instructive systems of classification so much needed for the 

 varieties of all our widely disseminated and variable cultivated 

 crops. 



SUMMARY. 



AGRICULTURAL HISTORY AND DISTRIBUTION. 



All cultivated sorghums are held to have been derived from the 

 wild species Andropogon halepensis. 



Many facts point to an independent origin in tropical Africa and in 

 India, which are the two great centers of sorghum production, each 

 occupied by an enormous number of varieties. 



Sorghums, as crops cultivated for human food, date from the most 

 remote historic times. 



In varying forms sorghum is found abundantly throughout Africa 

 and across the southern half of Asia. It is less abundantly distributed 

 in southern Europe and in the United States and the West Indies. 



Sorghum varieties furnish the chief cereal food of the native mil- 

 lions in Africa. 



In British South Africa kafirs and sorgos are the predominating 

 groups, represented by numerous varieties. Most of the kafirs and 

 sorgos cultivated in the United States were obtained in this region, 

 which is similar in many respects to much of our Great Plains area. 



Throughout equatorial Africa some new and little-known groups, 

 related to the durras, are the leading types. Forms of the Roxburghii 

 group also occur commonly, while kafirs and sorgos are rare. All 

 these tropical forms are late in maturing. 



In Abyssinia and throughout the Sudan these new durra-like 

 groups predominate. The Roxburghii group diminishes in impor- 

 tance, while kafirs and sorgos disappear as native types. Few of the 

 local varieties are immediately adapted to our conditions. 



In North or Mediterranean Africa only clurra groups are found. 

 Those forms found in Egypt are Sudanese; the white durra in the 



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