750 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



annuals or perennials, with flat blades and terminal panicles of 1- to 

 5-jointed tardily disarticulating racemes. Type species, Sorghum 

 saccharatum (L.) Moench. Name from Sorgho, the Italian name of 

 the plant. 



The sorghums and Johnson grass sometimes produce cyanogenetic 

 compounds in sufficient abundance, especially in second growth, to 

 cause prussic-acid poisoning in grazing animals. The leaves are often 

 splotched with purple, due to a bacterial disease. 



Plants perennial 1. S. halepense. 



Plants annual 2. S. vulgare. 



1. Sorghum halepense (L.) Pers. Johnson grass. (Fig. 1668.) 

 Culms 50 to 150 cm tall, from extensively creeping scaly rhizomes; 

 blades mostly less than 2 cm wide; panicle open, 15 to 50 cm long; ses- 

 sile spikelet 4.5 to 5.5 mm long, ovate, appressed-silky, the readily 

 deciduous awn 1 to 1.5 cm long, geniculate, twisted below; pedicellate 

 spikelet 5 to 7 mm long, lanceolate. % (Holcus halepensis L.) — 

 Open ground, fields, and waste places, Massachusetts to Iowa and 

 Kansas, south to Florida and Texas, west to southern California (fig. 

 1669); native of the Mediterranean region, found in the tropical and 



warmer regions of both hemispheres. Culti-^ 

 vated for forage; on account of the difficulty 

 of eradication it becomes a troublesome weed. 

 2. Sorghum vulgare Pers. Sorghum. Dif- 

 fering from S. halepense in being annual and 

 more robust, o (Holcus sorghum L.) — This 

 species has been cultivated in warmer regions 

 FlGU » r 51lSS tionof since prehistoric times for the seed, which has 



been used for food, for the sweet juice, and for 

 forage. In the United States it is cultivated under the general name 

 of sorghum. 



There are many varieties or races of cultivated sorghums, all of 

 which have the same chromosome number (10) and which fall natur- 

 ally into distinct groups, the chief of which (in the United States) are 

 sorgo, kafir, durra, milo, feterita, shallu, kaoliang, broomcorn, and 

 Sudan grass. Sorgo includes the varieties known collectively as sweet 

 or saccharine sorghums, in which the juice in the stems is abundant 

 and very sweet. In this country sorgo is cultivated chiefly in the 

 region from Kansas and Texas to North Carolina for forage and for 

 the juice which is made into sirup. The large panicles of broomcorn, 

 grown especially in Oklahoma and Illinois, furnish the material for 

 brooms. The other forms are grown for forage or for the seed which 

 is used for feed. Sudan grass (S. vulgare var. sudanense (Piper) 

 Hitchc.) is now grown extensively for pasture and for hay. This is 

 a rather slender annual, 1 to 2 m tall with comparatively narrow 

 blades and an open spreading panicle. This variet}*- is more distinct 

 than the others. 



The differences between most of the varieties are so indistinct and 

 so unstable because of intercrossing as to make it very difficult to 

 assign descriptive limits. The application of botanical names is 

 uncertain, and it seems best, therefore, not to assign to them definite 

 varietal or specific Latin names. 



The following names have been applied in American literature to 

 some of the more important varieties. 



