50 HISTORY AND DISTRIBUTION OF SORGHUM. 



By the middle of the nineteenth century fully thirty botanical spe- 

 cies had been described from cultivated forms and about sixty bi- 

 nomial combinations had been made. 



Only a part of these so-called species can be identified with exist- 

 ing available forms to-day. 



Since about 1850 the differing forms of cultivated sorghums have 

 been regarded as botanical or horticultural varieties. Descriptions 

 have commonly been drawn from the heads and seeds only, ignoring 

 the characters of the plant. 



During the past half century numerous classifications of varying 

 scope and completeness have been constructed. Any satisfactory 

 classification must take account of the habit and characters of the 

 entire plant and have regard for natural groups. 



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