42 GRAMINEAE (GRASS FAMILT>» 



Spikelets placed flatwiseon theraohis ..Vw' . ' . . . , 62. Agropyron. 

 Spikelets 2 or more at each joint of the rachis. 



Spikelets 1-flowered , . . , 63. Hordeum. 



Spikelets 2-many-flowered, 



Rachis continuous . 64. Elymus. 



Kachis readily separating into joints . . . . . 66. Sitanion. 



1. ANDROPOGON L. Beard Grass or Bltte-stem 



Perennials, usually with long narrow leaves, apd terminal and axillary 

 racemes. Spikelets in pairs at each node of the jointed hairy rachis, one sessile 

 and perfect, the outer with a pedicel and either staminate, empty, or reduced 

 to a smgle glume. Perfect spikekt consisting of i glumes ; the outer 2 coriaceous, 

 the second keeled and acute; the two inner hyahne, the fourth more or less 

 awned and subtending a paliet and perfect flower. Stamens 1-3. Grain free. 



Racemes solitary, distinct, i-3 at each node . . . . . .1. A. scoparius. 



'^ acemes in pairs or approximate. 



Awn loosely spiral, geniculate 2. A. furcatua. 



Racemes in pairs or approximate. 



Awn loosely spiral, geniculate ,._,_,_._. 



Awn straight or sometimes wanting 3. A. Hallii; 



1. Andiopogon scoparius Michx. Fl.Bor. Am. 1: 57. 1803. Culms tufted, 

 6-12 dm. tall: sheaths sometimes glaucous: leaves 15-30 cm. long, scabrous: 

 spikes 25-50 mm. long, loose, distinct, and 1-3 at each node, on long-exserted 

 slender peduncles: rachis slender, flexuous; joints and pedicels ciUate with long 

 spreading hairs: outermost glume of sessile spikelet about 6 mm. long; awn 

 spiral, 10-12 mm. long; pediceled spikelet a single awn-pointed glume. — ^Dry, 

 sandy soil; throughout our rangel 



2. Andropogofi furcatus Muhl. Willd. Sp. PI. 4: 919. 1806. Culms stout, 

 9-18 dm. tall: sheaths smooth and glabrous: leaves 15-45 cm. long: spikes 2-6, 

 in pairS' or appifoximate, 5-10 cm. long; joints of the rachis and pedicels 

 ciliate with short hairs: outermost glume of sessile spikelet 6-8 mm. long; awn 

 of the sterile lemma loosely spiral, geniculate, 1(>-14 mm. long; pediceled 

 spikelet of 4 gliunes. — Eastern part of our range and eastward. 



3. Andropogon Hallii Hack. Sitz. Akad. Wiss. Wien 89: 127. 1884. Culms 

 robust, 9-18 dm. tall, more or less glaucous: sheaths solhewhat glaucous: 

 leaves 3 dm. long or less: spikes 2-5, in pairs or approximate, 5-10 cm. long: 

 joints of the rachis and pedicels villous with long hairs: outermost glume of 

 sessile spikelet about 8 mm. long, acuminate, glabrous at base, from sparingly 

 to copiously silky-pubescent toward the apex; awn of the sterile lemma 

 straight, 4-10 mm. long, or sometimes wanting; pediceled spikelet consisting 

 of 4 glumes, generally Ikrgbr than the sessile spikelet and inclosing three 

 stamens. — ^Dry, Sandy soil of the plains and foothills; along the eastern border 

 of the Rocky Moimtains. 



2. AMPHILOPHIS Nash 



Perennials, usually with flat leaves and showy, often silvery-white panicles, 

 the axis short, making the panicle appear fan-like; or elongated with the 

 branches more scattered. Racemes usually numerous, the internodes with 

 manifestly thickened margins, the median portion thin and translucent; the 

 pedicels of the same structure, the margins ciliate with long hairs. Sessile 

 spikelets of 4 glumes, the first one 2rkeeled, the second 1-keeled, the lemmas 

 hyahne, the latter very narrow, stipe-hke, somewhat thickened, gradually 

 merging into a usually geniculate, contorted or spiral awn, or the awn rarely 

 wanting. Pedicellate spikelets staminate and similar to the sessile, or sterile 

 and smaller. Stamens 3. Styles distinct; stigmas. plumose. Grain fiee, in- 

 closed in the lemmas. 



1. Amphilophis Torreyanus (Steud.) Nash, Brit. Man. 71. 1901. Culms 

 erect, 4r-10 dm. tall, the nodes naked: sheaths more or less glaucous: leaves 

 7-17 cm. long, glaucous: spikes 25-35 mm. long, in a terminal long-exserted 

 panicle 4-10 cm. long; outermost glume of sessile spikelet 3—1 mm. long, about 



