POACEAE 137 
2. Bouteloua hirsüta Lag. Stems erect, 1.5-5 dm. tall: leaf-blades mostly at the 
base of the stem, 2-13 cm. long, 2 mm. wide or less, erect or ascending, flat, rough, spar- 
ingly papillose-hirsute near the base, especially on the margins: spikes 1-4, 1-5 cm. long, 
erect or ascending, the rachis extending beyond the spikelet in a conspicuous point: 
spikelets 5-6 mm. long. 
In dry soil, especially on prairies, Illinois to North Dakota, Texas and Arizona, and in southern 
peninsular Florida. Summer and fall. 
3. Bouteloua Bürkei Scribn. Perennial. Stems tufted, 3 dm. tall or less: leaf- 
blades spreading, often involute, 1-3 cm. long, about 1 mm. wide, stiff: spikes 3-6, erect, 
1-2 em. long: spikelets diverging from the rachis, about 2.5 mm. long, exclusive of the 
awns. 
In dry soil, central and western Texas. Alsoin Mexico. Spring and summer. 
4. Bouteloua trífida Thurb. Perennial. Stems tufted, 3 dm. high or less : leaf- 
blades spreading, often involute, 4 dm. long or less, about 1 mm. wide: spikes 2-6, erect, 
1.5-3 em. long: spikelets diverging from the rachis, 3-4 mm. long, exclusive of the awns. 
In dry soil, central Texas to New Mexico. Alsoin Mexico. Spring and summer. 
5. Bouteloua eriópoda Torr. Perennial. Stems tufted, 3-6 dm. tall, at least the 
lower internodes densely villous : leaf-blades 1.5 dm. long or less, 1-2 mm. wide, usually 
attenuated into a long slender point, erect : spikes 2-5, erect, 2-5 em. long: spikelets di- 
verging from the rachis, 6-8 mm. long, exclusive of the awns. 
In dry soil, central Texas to Arizona. Summer and fall. 
6. Bouteloua microstáchys Fourn. Annual. Stems tufted, erect or ascending, 
slender, 1-3 dm. tall, sometimes branching : leaf-blades spreading or ascending, flat, 1-7 
em. long, 1-2 mm. wide: spikes 2-7, usually curved, ascending, 1.5-3 cm. long : spikelets 
diverging from the rachis, 2-3 mm. long, exclusive of the awns, the flowering scale 
strongly pubescent, the rachilla with a terminal tuft of hairs. 
In dry soil, southern Texas to southern California. Alsoin Mexico. Summer and fall. 
84. ATHEROPOGON Mull. 
Perennial grasses, with narrow flat leaf-blades and an inflorescence composed of numer- 
ous scattered short few-flowered spikes. Spikelets 1-flowered, sessile, crowded in 2 rows, 
imbricated, the rachilla extending beyond the flower, its summit bearing scales or awns. 
Scales 3 or more, the 2 lower empty, unequal, narrow, acute, keeled, the third scale thin- 
ner and broader, 3-toothed at the apex, the teeth more or less awned, enclosing a narrow 
hyaline 2-toothed palet and a perfect flower, the small upper scales empty, awned. Stamens 
3. Styles distinct. Stigmas plumose. 
1. Atheropogon curtipéadulus (Michx.) Fourn. Stems 3-9 dm. tall, tufted : leaf- 
blades 5-30 cm. long, 4 mm. wide or less, flat or involute, rough : spikes 6-16 mm. long, 
widely spreading or reflexed : spikelets 4-12, diverging from the rachis, 7-10 mm. long. 
[Bouteloua racemosa Lag. ] 
In dry soil, Ontario to Manitoba, New Jersey, Kentucky, Georgia (according to Feay and Chap- 
man) and Texas. Alsoin Mexico. Summer and fall. 
85. TRIATHERA Desv. 
Annual or perennial grasses, with flat or involute leaf-blades and slender nanicles com- 
posed of short slender one-sided spikes. Spikelets narrow, appressed, the rachilla terminat- 
ing in 3 stout awns. Scales 3, long-acuminate, the 2 outer empty, unequal, the flowering 
scale 3-toothed at the apex, the teeth usually awned. Stamens 3. Styles distinct. Stig- 
mas plumose. 
l. Triathera aristidoides ( H.B.K.) Nash. Stems slender, 1-4 dm. tall, wiry, finally 
somewhat branched : leaf-blades 2-10 cm. long, 1-2 mm. wide, flat, or sometimes involute : 
panicle slender, 4-10 em. long, consisting of 5-20 spreading spikes 1-1.5 cm. long, their 
bases strongly appressed-pubescent with long silky hairs : spikelets 2-3 in each spike. 
In dry places, central Texas to southern California. Also in Mexico. Summer and fall. 
86. FOLYODON H.B.K. 
Perennial grasses, with flat or involute leaf-blades, and short spikes arranged in slender 
panicles. Spikelets 1-flowered, appearing clustered by reason of the very short internodes 
of the rachis. Scales 5 or 6: the 2 outer empty, narrow, acuminate ; third scale 3-awned, 
enclosing a perfect flower; remaining scales empty, the lower 3-awned, the uppermost usually 
reduced to 1-3 awns. Stamens 3. Styles 2, slender, distinct, distantly inserted. Stigmas 
plumose. 
