GRAMINEAE (GRASS FAMILY) 43 



equaling the terminal hairs of the rachis-joints, lanceolate, acute; awn 8-16 

 mm. long, spiral; pediceled spikelet rudimentary. (Andropogon Torreyanus 

 Steud.) Kansas and Colorado; extending southward and westward to Ne- 

 vada. 



3. SORGHASTRUM Nash 



Annual or perennial, generally tall grasses, with long narrow flat leaves and 

 terminal panicles. Spikelets in pairs or threes at the end of the branches; 

 one sessile and perfect; the lateral pediceled, empty, or reduced to the peaicel 

 only. Perfect spikelet consisting of 4 glumes; the two outer indurated and 

 shining; the inner hyaline, the fourth awned and subtending a palet and per- 

 fect flower, or the palet sometimes wanting. Stamens 3. Styles distinct; 

 stigmas plumose. Grain free. 



1. Sorghastrum nutans (L.) Nash, in Small Fl. 66. 1903. Stout perennials, 

 9-18 dm. high: lower leaves 3 dm. or more in length: panicle 1-3 dm. long, 

 brownish-yellow; branches 5-10 cm. long, erect-spreading: spikelets erect or 

 somewhat spreading; first glume of sessile spikelet 6-8 mm. long, pubescent 

 with long hairs; second glume glabrous; awn 1-2 cm. long, the column having 

 but a single bend; lateral spikelets wanting. Chrysopogon nutans. Extend- 

 ing into our range from the eastern United States. 



4. SORGHUM Pers. 



Annual or perennial grasses, with long, broad, flat leaves and terminal, 

 ample panicles. Spikelets in pairs at the nodes, or in threes at the ends of the 

 branches, one sessile and perfect, the lateral pediceled, staminate or empty. 

 Sessile spikelet consisting of 4 glumes, the outer indurated and shining, ob- 

 scurely nerved, inner hyaline, the fourth awned and subtending a small palet 

 and perfect flower, or palet sometimes wanting. Stamens 3. Styles distinct. 

 Grain free. 



1. Sorghum halepense (L.) Pers. Syn. 1: 101. 1805. Stout perennial, 

 9-20 dm. tall: sheaths smooth; leaves 3 dm. or more long, 6-25 mm. wide: 

 panicle 15-45 cm. long: outer glumes of sessile spikelet 4-6 mm. long, usually 

 purplish, pubescent with long appressed hairs; awn when present 8-16 mm. 

 long. JOHNSON GRASS. Introduced in fields and waste places. 



5. HILARIA H.B.K. BLACK BUNCH-GRASS 



Caespitose or decumbent perennials, often stoloniferous, with flat or in- 

 volute leaves and terminal solitary spikes. Spikelets sessile, in groups of three 

 at each joint of the zigzag continuous rachis, forming terminal spikes, the 

 several groups falling off entire; the two outer or anterior spikelets staminate 

 and 2-3-flowered, the posterior or inner one pistillate or hermaphrodite. ;ui<l 

 1-flowered. Glumes firmer in texture than the lemmas, unequal, many-nerved, 

 more or less connate below, entire at the apex or more often divided, usually 

 unequally 2-lobed with one to several intermediate awns or awn-like divi- 

 sions; lemmas much narrower. Stamens 3. Styles connate below; stigmas 

 shortly plumose. Grain ovate or oblong, included within the lemmas, free. 



1. Hilaria Jamesii (Torr.) Benth. Journ. Linn. Soc. 19: 62. 1881. Rather 

 coarse, branching, 3-5 dm. high: spikes erect, often purplish, 5-8 cm. long: 

 spikelets 8-10 mm. long, hairy at base; staminate spikelets 2-flowered, the 

 glumes 5-nerved, the outer glume with an awn from the back longer than the 

 spikelet, the inner unawned. Mesas and table-lands from southern Wyoming 

 to New Mexico and southern California. 



6. P ASP ALUM L. 



Perennials, various in habit; with usually flat leaves and 1-flowered spike- 

 lets borne singly or in pairs in 2 rows on 1-sided spikes, which are single, in 



