BOTAXY OF SORGHUJI. 59 



By the crossing of these races, and the inter-crossing of the resulting hybrids, 

 many varieties have been produced. Introduced into regions of different lati- 

 tudes, exposed to influences of various conditions of climate and soil, these 

 ■were subjected to further modifications, which, permanently retained by inheri- 

 tance through future generations, show their peculiarities less in the morpho- 

 logical features than in their physiological relations, of much more importance 

 to the cultivator, by their influence upon the life of the plant and the product 

 of its activity. In the endeavor to attain those modifications which shall ap- 

 pear most favorable under given conditions, in respect to the time required for 

 ripening, the percentage of sugar, and also the capacity of resisting unfavorable 

 influences, the number of permanent variations is constantly increasing in the 

 United States. 



The difficulty of assigning them their proper places, and discovering their 

 relationship and ancestry, increases with the obliteration of the original type. 



In general, the following well established varieties can be regarded as belonc'- 

 ing to the first of these races: regular Sorgho, Chinese sugar-cane, Honduras, 

 Mastodon, Honey cane, Sprangle top, Honey-top, Link's hybrid, and other va- 

 rieties produced by crossing with varieties of African ancestry with rather ex- 

 panded panicles. 



To the second, or the African race, belong the Liberian, Imphee, Oomseeana, 

 Neeazana, White African, with the varieties produced in this country known as 

 Black top, Bear tail, Iowa Red top. White mammoth, Wolf tail. Gray top. The 

 Early Amber and Early Orange are forms of prominently African type. The 

 identification of these various sorts is extremely difficult, and can onlj- be ac- 

 complished by artificial methods, regardless of their natural affinities, as has 

 been successfully attempted by Dr. Collier. 



C. G. Nees ab Esenbeck, in his Agrostographia Capeusis, 1853, p. 

 86, classifies the sorghums as follows : 



1. Sorghum bicolor. — Willd. 



Holcus bicolor. — Willd. 

 Andropogon cernus. — Kunth. 



2. a. Soi'ghum saccharatum. — Pers. 



Sorghum saccharatum. — Pers. 

 Holcus saccharatus. — Kunth. 

 Holcus Caffrorum. — Thunb. 

 Holcus Caffer. — Arduini. 



Sorghum Caffrorum. — P. de Beauv. ' 



Sorghum Arduini. — Jacq. 

 Holcus dochna. — Forsk. 

 6. Rubens. 



Sorghum rubens. — Willd. 

 Andropogon rubens. — Kunth. 



3. Sorghum Usorum. — X. ab. E. 



Holcus Caffrorum. — Thunb. 



Sorghum Caffrorum panicula compactiori apud. — R. et Sch. S. 



4. Sorglium halapense. — Pers. 



Holcus halapensis. — Sibth. 

 Trachypogon avanaceus. — N. ab E. 



