515 
one-half to two-thirds as long as the second; the second nearly equaling or often 
slightly exceeding the attenuate floret; awns equal, capillary, 3 to 4 em. long (A. 
purpurea Nutt.)—Dry land, throughout Texas and westward. Var, FENDLERIANA 
(Steud.) Vasey has culms tufted and mostly simple (2to4 dm. High), numerousinvolute- 
filiform radical leaves, and erect panicle about L dm. long.—High plains, Texas and 
westward, Var. MICRANTHA Vasey has tufted branching very slender culms 3 to 
5 dm, high, involute curved leaves, a loose flexuous panicle, short capillary branches 
hearing few spikelets on curved capillary pedicels, and spikelets 10 to 12 mm. long.— 
Western Texas. Var, Catirornica Vasey is like the preceding, but larger, with 
the flat or involute leaves usually straight, panicle 1 to 2 dm, long, branches fascieu- 
late (the longer 3 to5 em. long) and naked below, and spikelets and awns generally 
longer than in the species. —Texas to California. Var. Hooker Trin. has mostly 
simple culms, with involute leaves, loose panicle, spikelets nearly 2 em. long, and 
awns 3 to 8 em. long.—Western Texas and northward. 
14. A. oligantha Michx. Culms much branched throughout, 3 to 5 dm. high: 
panicles lateral and terminal, 1 to 1.5 di. long, nearly simple, loose; the few short 
branches or single spikelets rather divergent: spikelets nearly 2 em, long; first 
empty glume 5-nerved; both awn pointed, nearly equal, about as long as the atten- 
uate floret; awns capillary, 3 to 5 cm. long,—Texas and eastward. 
* * Panicle broad and spreading, with divergent branches, naked below. 
+ Awns nearly equal, 1 to 2 em. long. 
15. A. Havardii Vasey. Culins 1.5 to ddim. high, slender, simple, tufted: leaves 
involute: panicle loose, flexuous, 1 to 1.5 dm. long: spikelets about 1 em. long, on 
slender capillary pedicels; empty glumes I-nerved, awn-pointed, equaling or 
slightly exceeding the floret; floral glume slender and twisted above; awns 1.5 to 
2 em. long.—Western Texas and New Mexico. 
16. A. Humboldtiana Trin. & Rupt. Culms rigid, simple, 3to6dm, long: leaves 
narrow, tlat or convolute, straight and rigid: panicle open, erect, 2 to 4 dm, long; 
branches alternate or in twos, divergent or horizontal, straight and rigid, 5 to 10 
em. long: spikelets about 1 cm. long; empty glumes usually nearly equal and about 
equaling the hispid floret; awns nearly 2 cm. long, lateral ones slightly shorter.— 
Western Texas to California. Var. MINOR Vasey, of the same range, is smaller, 
with leaves nearly equaling the culm, and smaller spikelets with shorter nearly 
equal glumes. 
++ Lateral awns minute or wanting. 
17. A. Scheidiana Trin. & Rupt. Culms erect, 4 to 6 dm. high, mostly simple: 
leaves couvolute-tiliform : panicle 2 to 4 dm. long, open, pyramidal; branches 
rigid, spreading or horizontal, naked below the outer third: spikelets 10 to 15 mm. 
long; empty glumes nearly equal, bristle-pointed, shorter than the attenuate 
twisted floral glume; lateral awns 2 mm. long or less; middle awn about 1 em, 
long, turned backward.—Texas to Arizona. 
18. A. divergens Vasey. Culms slender, simple, about 3 dm. high: panicle 1 to 
2 dm. long, pyramidal, usually included below in the upper sheath; branches 
single or in twos, often divided nearly to the base and appearing verticillate, again 
subdivided and spikelet-bearing beyond the middle: spikelets 10 to 12 mm. long; 
empty glumes subequal, the lower one usually slightly longer, equaling the 
attenuate twisted floret; lateral awns minute or wanting; middle awn about 1 em. 
long, nearly straight.—Texas to Arizona, 
27. STIPA L. (FEATHER-GRASS, ) 
Spikelets 1-flowered, paniculate or subspicate, pedicellate: empty 
glumes persistent, thin or chartaceous, acute or bristle-pointed, nearly 
