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



Kafir. S. vulgare var. caffrorum (Thunb.) Hubb. and Render. 

 Shallu. S. vulgare var. roxburghii (Stapf) Haines. 

 Durra. S. vulgare var. durra (Forsk.) Hubb. and Rehder. 

 Broomcorn. S. vulgare var. technicum (Koern.) Jav. 

 Sorgo. S. vulgare var. saccharatum (L.) Boerl. 



Tunis grass (S. virgatum (Hack.) Stapf) is a tall annual with a nar- 

 row slender open panicle and narrowly-lanceolate green finely-awned 

 spikelets. — Africa. Has been tried at experiment stations but has 

 not been brought into commercial cultivation, being inferior to 

 Sudan grass. 



148. SORGHASTRUM Nash 



Spikelets in pairs, one nearly terete, sessile, and perfect, the other 

 wanting, only the hairy pedicel being present; glumes coriaceous, 

 brown or yellowish, the first hirsute, the edges inflexed over the 

 second; sterile and fertile lemmas 

 thin and hyaline, the latter extend- 

 ing into a usually well-developed 

 bent and twisted awn. Perennial, 

 erect, rather tall grasses, with auri- 

 cled sheaths, narrow flat blades, and 



Figure 1672.— Sorghastrum elliottii, X 1. 

 (Harper 1718, Ga.) 



Figure 1671.— Distribution of 

 Sorghastrum nutans. 



narrow terminal panicles of one- to 

 few- jointed racemes. Type species, 

 Sorghastrum avenaceum (Michx.) 

 Nash (S. nutans). Name from Sorg- 

 hum and the Latin suffix astrum, a 

 poor imitation of, alluding to the 

 resemblance to Sorghum. 



The most important species, S. nutans, is a common constituent 

 of wild or prairie hay in the eastern part of the Great Plains region. 



Awn usually 15 mm long or less, once geniculate. Panicle rather dense, yellow- 

 ish 1. S. NUTANS. 



Awn 20 to 35 mm long, twice-geniculate, twisted below the second bend. 



Spikelets chestnut-brown, the ultimate branchlets with a few long hairs at the 



tip only; panicle loose, not unilateral 2. S. elliottii. 



Spikelets yellowish brown, the upper portion of the ultimate branchlets con- 

 spicuously long-hairy toward the tip; panicle distinctly unilateral 



3. S. SECUNDUM 



1. Sorghastrum nutans. (L.) Nash. Indian grass. (Fig. 1670.) 

 Culms 1 to 2.5 m tall from short scaly rhizomes; blades elongate, flat, 

 mostly 5 to 10 mm wide, tapering to a narrow base, scabrous; 

 panicle narrow, yellowish, rather dense, 15 to 30 cm long, contracted 

 and darker at maturity; summit of branchlets, rachis joints, and 

 pedicels grayish-hirsute; spikelets 6 to 8 mm long, lanceolate, hirsute, 

 the awn 1 to 1.5 cm long, once-geniculate. % — Prairies, open 

 woods, and dry slopes, Quebec and Maine to Manitoba and North 

 Dakota, south to Florida and Arizona; Mexico (fig. 1671). 



