516 
equal, exceeding the floret; floral glume coriaceous or indurate, closely 
folded about the smaller palet and terete or fusiform grain, with a 
simple twisted and bent awn articulated with its apex; hairy stipe 
sharp and prominent: Perennials, growing in bunches: leaves narrow, 
usually involute or convolute. , 
*dwns 6 to 20 times as long as the florets. 
+ Awns plumose. 
1. S, pennaia L., var. Neo-Mexicana Thurb, Culms 4 to 8 dim. high, simple: 
radieal leaves almost equaling the culm, convolute, rather rigid: panicle somewhat 
secund, narrow, 1 to 2 dm. long: spikelets erect; empty glumes 3 to 4 cin, long, 
nervose below, with long attenuate points, twice as long as the brown hairy stipe 
and shining floret; awn 1 to 2 dm. long.—Mountains, western Texas to Arizona. 
+ + Awns naked. 
+ Florets small, 7 mm. long or less. 
9, S.tennuissima Trin. Culms very slender, 4 to 6 dm. high: leaves convolute- 
filiform, nearly equaling the culm: panicle 2 to 4 dm. long, usually included below: 
empty glumes about 7 mm. long, with long attenuate membranaceous points 3 to 5 
times as long as the oblong floret; awn capillary, 6 to 10 em. long.—Mountains, 
western Texas. 
8. S. flexuosa Vasey. Culms 6 to 10 dm. high: leaves flat or involute: panicle 
rather flexuous and somewhat spreading, 2 to 3 dm, long: empty glumes 6 to 10 mm. 
long, acute or acuminate, with membranaceous margins, about one-third longer than 
the terete floret; awn slender, 6 to 8 em, long.—Mountains and high plains, central 
Texas to Arizona and Mexico, 
++ 4+ Tlorets larger, 10 mm. long or more. 
4. S. leucotricha Trin. Culms 3 to 6 dim. high: leaves flat or involute; sheaths 
somewhat inflated: panicle erect, or secund and slightly nodding: spikelets about 
15 mm. long; empty glumes membranaceous-margined; floret 1 em. long, white 
silky, or glabrate and brown at maturity, with a pit in the constricted neck below 
the apex; awn pubescent below, 6 to 8 em. long.—Central Texas and westward to 
Arizona. 
5. S. avenacea L. (BLACK oat-GRass.) Culms 6 to 10 din. high: leaves flat or 
involute; upper one with a long inflated sheath and short blade: panicle rather 
loose, 1 to 2 dm. long, included below: spikelets about 15 mm. long; empty glumes 
green with membranaccous margins; floret 10 to 12 mm. long, brown or nearly 
black, with a prominent brown hairy stipe, hispidulous abeve, constricted to a very 
short neck; awn nearly smooth, 6 to 9 em. long.—Dry land, Texas and eastward. 
** duns 2 to 4 times as long as the florets. 
6. S. viridula Trin., var. ROBUSTA Vasey. (SLEEPY GRAss.) Culmsrather robust, 
1to 2m. high: leaves involute, 3 to6dm, long: panicle erect, dense, 3 to 5 dm. long: 
spikelets about 1 em. long; empty glumes acute, one-fourth longer than the tloret; 
floral glume hairy with a short stipe and a thin tuft of white hairsat the apex; awn 
2 em. long.—Mountain valleys, western Texas and northward to Colorado, This 
grass is said to have a narcotic effect on horses and cattle. 
7. S. Pringlei Scribn. Culms 6 to 10 dm. high: leaves mostly flat, rather rigid: 
panicle loose or contracted, 1 to 2 dm, long; branches few-flowered, usually naked 
below: spikelets about 1 cm. long, rather thick for the genus; empty glumes but 
little longer than the brown pubescent tloret; awn hispidulous, 2 to 3 cm. long.— 
Mountains, western Texas to southern California, 
