154 MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 



perfect with a long, geniculate, villous awn, its pedicel obliquely dis- 

 articulating, forming a sharp pointed callus below the spikelet; first 

 glume firm, rounded on the back, obtuse. 



1. Trachypogon montufari (H. B. K.) Nees, Agrost. Bras. 342. 1829. 



Andropogon montufari H. B. K., Nov. Gen. et Sp. 1: 184. 

 1816. 



Mohave, Gila, Cochise, Santa Cruz, and Pima Counties, 1,000 to 

 6,000 feet, rocky hills, September to October. Southern Texas, New 

 Mexico, and Arizona, south to Argentina. 



79. ELYONURUS 



Rather slender, erect perennial with involute leaf blades and solitary, 

 erect, woolly racemes; spikelets in pairs at each joint of the tardily 

 disarticulating rachis, the sessile spikelet perfect, the pedicellate one 

 staminate, similar to the sessile one; first glume firm, flattened, acute, 

 the margins enclosing the second glume ; lemmas thin, hyaline, awnless. 



1. Elyonurus barbiculmis Hack, in D. C, Monog. Phan. 6: 339. 



1889. 



Elyonurus barbiculmis parviflorus Scribn., U. S. Dept. Agr., 

 Div. Agrost. Cir. 32: 1. 1901. 



Mohave, Cochise, Santa Cruz, and Pima Counties, mostly 4,000 to 

 6,000 feet, rocky slopes and canyons, July to October, type from 

 Arizona (Lemmon 2926). Western Texas to Arizona and northern 

 Mexico. 



This grass, where sufficiently abundant, affords good grazing. 



80. HACKELOCHLOA 



Erect or spreading, freely branching annual with short, solitary, 

 exserted or partly included racemes; spikelets in pairs, awnless, very 

 dissimilar, the sessile one perfect, the pedicellate one staminate, con- 

 spicuous ; first glume of the sessile spikelet broad, alveolate, the margins 

 clasping the fused rachis joint and pedicel of the staminate spikelet. 



1. Hackelochloa granulans (L.) Kuntze, Rev. Gen. PL 2: 776. 1891. 



Cenchrus granularis L., Mant. 2: 575. 1771. 



Cochise, Santa Cruz, and Pima Counties, sandy plains and waste 

 places, August to October. Georgia and Florida to Louisiana, New 

 Mexico, and Arizona; tropics of both hemispheres, introduced in 

 America. 



81. TMPSACUM. Gamagrass 



Robust perennials with broad, flat leaf blades and monoecious 

 terminal and axillary inflorescences, the pistillate part below, the 

 staminate part above on the same rachis ; staminate spikelets 2-flowered, 

 in pairs, one sessile, the other sessile or pedicellate; pistillate spikelets 

 solitary on opposite sides at each joint of the thick, hard, articulate 

 lower part of the rachis, sunken in hollows, consisting of 1 perfect 

 floret and a sterile lemma. 



This genus is of interest mainly on account of its relationship to 

 Indian-corn or maize. 



