MANUAL OF THE GRASSES OF THE UNITED STATES 



773 



elongate, 2 to 8 mm. wide, sometimes 

 wider, very scabrous on the margins; 

 inflorescence 20 to 40 cm. long, the 

 pairs of racemes on long slender 

 flexuous peduncles; racemes about 2 

 cm. long, reddish brown; fertile 

 spikelets mostly 5 to 7 in each ra- 

 ceme, 3 to 4 mm. long, flattened from 

 the back, pubescent with dark-red 

 hairs, the pedicels and rachis joint 

 ciliate with red hairs; awn 15 to 20 

 mm. long, twice geniculate, twisted, 

 red brown, hispidulous. % 

 Tropics of the Old World ; introduced 

 in tropical America; sparingly culti- 



vated in Florida (where it has 

 escaped) and along the Gulf coast. 

 Adapted to conditions in the regions 

 mentioned, but only moderately val- 

 uable as a forage grass. The native 

 name in Brazil is jaragua. 



Hyparrhenia hirta (L.) Stapf. Usu- 

 ally not more than 1 m. tall; blades 

 usually less than 3 mm. wide, more 

 or less involute, flexuous; racemes 

 whitish or grayish silky- villous. % 

 — Warmer parts of the Old World; 

 cultivated at the Florida State Experi- 

 ment Station and probably elsewhere. 

 Appears to have little forage value. 



156. SORGHUM Moench 



Spikelets in pairs, one sessile and fertile, the other pedicellate, sterile but 

 well developed, usually staminate, the terminal sessile spikelet with two 

 pedicellate spikelets. Tall or moderately tall annuals or perennials, with flat 

 blades and terminal panicles of 1- to 5-j ointed 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 com- 

 pounds 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. 1177.) Culms 

 50 to 150 cm. tall, from extensively 

 creeping scaly rhizomes ; blades most- 

 ly less than 2 cm. wide; panicle open, 

 15 to 50 cm. long; sessile spikelet 4.5 

 to 5.5 mm. long, ovate, appressed- 

 silky, the readily deciduous awn 1 to 

 1.5 cm. long, geniculate, twisted be- 

 low; pedicellate spikelet 5 to 7 mm. 

 long, lanceolate. % (Holcus hale- 

 pensis L.) — Open ground, fields, and 

 waste places, Massachusetts to Iowa 

 and Kansas, south to Florida and 

 Texas, west to southern California; 

 native of the Mediterranean region 

 found in the tropical and warmer 

 regions of both hemispheres. Culti- 

 vated for forage, but on account of 

 the difficulty of eradication it becomes 

 a troublesome weed. 



2. Sorghum vulgare Pers. Sor- 

 ghum. 16 Differing from S. halepense 



in being annual and more robust. 

 O (Holcus sorghum L.) — This spe- 

 cies has been cultivated in warmer 

 regions 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 naturally into 

 distinct groups, the chief of which 

 (in the United States) are sorgo, 

 kafir, durra, milo, feterita, shallu, 

 kaoliang, and broomcorn. Sorgo in- 

 cludes the varieties known collective- 

 ly as sweet or saccharine sorghums, 

 in which the juice in the stems is 



16 For elaboration of cultivated sorghums see Snow- 

 den, J. D., THE CULTIVATED EACES OP SORGHUM. vii 



+ 272 pp. 1936. London. 



