CHAPTER XXXII 

 THE SORGHUMS (Andropogon sorghum) 



In its agricultural or restricted sense the term "sor- 

 ghum" includes only the saccharine varieties. In this 

 chapter the term will be used in its broad or botanical 

 sense which includes (a) the saccharine sorghums, (b) 

 the non-saccharine sorghums, commonly known as grain- 

 sorghums, (c) the broom-corns, and (d) the grass sorghimis, 

 most important of which are Sudan-grass, Johnson-grass, 

 and Tunis-grass. As the members of the latter group are 

 grown for forage only they. will not be treated in this text. 



459. Biological origin. — Authorities have generally 

 agreed that the cultivated sorghums were originally de- 

 rived from the well-known wild species, Andropogon hale- 

 pensis, commonly known in the United States as Johnson- 

 grass. However, it has been recently pointed out that the 

 wild forms of sorghum easily separate into two groups.^ 

 One group includes the perennials with root-stocks like 

 the various varieties of Johnson-grass; the other group 

 includes annuals without root-stocks, such as Sudan-grass 

 and Tunis-grass. These wild annual forms cross readily 

 with the cultivated sorghums, whereas the perennial forms 

 and the cultivated sorghums are crossed with considerable 

 difficulty. It would therefore seem that the original 

 prototype of our cultivated sorghums is to be found 

 among the wild annual forms of Andropogon sorghum, 

 1 Piper, C. v., "Forage Plants and Their Culture," p. 260. 

 372 



