STRUCTURE OF SORGHUM 383 



There are several species belonging to different genera of 

 grasses which with sorghum often pass under the name of 

 millet Such are Choetochloa italica, formerly Setaria italica^ 

 Panicum cms-gal II, P. coloniim, P. friimentaceum, P. mil- 

 iaceum, Penisetiini spicatiim (L.) R. & S. Several of these 

 species have numerous cultivated varieties and numerous com- 

 mon names. Much confusion exists as to their botanical 

 relationships and to the synonyms of the common names. 

 The cultivation of some of these millets is very ancient, and the 

 grain has been used extensively as human food. In the United 

 States these plants are raised chiefly for hay. Canary grass 

 {Phalaris canariensis L.), is raised for bird food, although 

 sometimes in southern Europe for human consumption. 



537. The Plant. — The roots of the sorghum plant are said to 

 have strong feeding capacity, which enables the plant to with- 

 stand unfavorable environment. The Kansas Station found that 

 the roots reach out laterally in all directions from two to six 

 inches from the surface. The culms vary in height with variety, 

 climate, season, soil and culture usually from four to eighteen 

 feet, with greater variations in extreme cases. The culms, like 

 those of maize, are solid. The leaves are abundant, rather 

 thicker and more glossy than in maize. The upper leaf sheath 

 sometimes extends around the lower portion of the head or spike ; 

 when in broom corn it is called the " boot." 



538. The Inflorescence. — The inflorescence is in a more or less 

 compact spike-like panicle, usually referred to as the head. The 

 different types vary greatly in the form, size, compactness of the 

 head ; the usual variations in length being from ten to eighteen 

 inches, except in broom corn, where the " brush " may be twent^-- 

 eight inches long. 



The spikelets are one-flowered, some being sessile and others 

 on pedicels of varying length, usually one of each at each 

 joint of the rachis. 



