136 POACEAE 



the lower ones subverticillate. Spikelets 1-flowered, narrow, sessile or nearly so, scattered, 

 appressed, the rachilla glabrous and prolonged beyond the flower, bearing at its apex a 

 small usually awned scale. Scales 4, the 2 lower empty, persistent, narrow, acute, or the 

 second short-awned, the third scale somewhat broader, shortly 2-toothed at the apex, bear- 

 ing a straight awn, and enclosing a narrow 2-keeled palet and a perfect flower ; fourth scale 

 empty, awned, the body often much reduced. Stamens 3. Styles distinct. Stigmas plu- 

 mose. 



Spikes spikelet-bearing their whole length : awn longer than the flowering scale. 1. G. amhiguus. 

 Spikes spikelet-bearing only above the middle : awn shorter than the flowering scale. 2. G. brevifolius. 



1. Gymnopogon ambiguus (Michx.) B.S.P. Stems 3-5 dm. tall, erect, or decum- 

 bent at the base : leaf-sheaths with a villous ring at the summit, crowded at the base of the 

 stem ; blades 2-10 cm. long, 4-12 mm. wide, lanceolate, crowded at the base, spreading : 

 spikes slender, the lower ones finally widely spreading, 1-2 dm. long : spikelets, exclusive 

 of the awn, 4-5 mm. long, the awn of the flowering scale 4-6 mm. long. [G. racemosus 

 Beauv.] 



In dry sandy soil, southern New Jersey to Missouri, Florida and Texas. Summer and fall. 



2. Gymnopogon brevifolius Trin. Stems 3-6 dm. long, decumbent at the base, 

 slender : leaf -sheaths sometimes crowded at the middle of the stem ; blades 2-5 cm. long, 

 2-8 mm. wide, lanceolate, usually spreading : spikes very slender, the lower ones finally 

 widely spreading and 1-1.5 dm. long : spikelets, exclusive of the awn, 3 mm. long, the 

 flowering scale short-awned. 



In dry soil, New Jersey to Florida and Mississippi. Summer and fall. 



82. SCHEDONNARDUS Steud. 



Annual grasses, with narrow almost subulate leaf-blades and an inflorescence consisting 

 of numerous long slender spikes arranged in an open panicle. Spikelets 1-flowered, acumi- 

 nate, scattered, appressed, sessile and alternate on opposite sides of the rachis. Scales 3, 

 membranous, the 2 lower empty, persistent, narrow, acuminate, somewhat unequal, the 

 third scale longer, at length rigid, enclosing a narrow shorter palet and a perfect flower. 

 Stamens 3. Styles distinct. Stigmas plumose. 



1. Schedonnardus paniculatus ( Nutt. ) Trelease. Stems 2-5 dm. tall, slender, erect, 

 rigid, branched at the base : leaf -sheaths crowded at the base of the stem, compressed ; 

 blades 2-5 cm. long, 2mm. wide or less, usually erect, flat: spikes numerous, widely spread- 

 ing, alternate, rigid, the lower ones 5-10 cm. long : spikelets 2.5-3 mm. long, appressed, 

 alternate. 



In dry soil, Manitoba and Assiniboia to Illinois, Texas and New Mexico. Summer and fall. 



83. BOTJTELOUA Lag. 



Annual or perennial grasses, with narrow flat or convolute leaf-blades, and an inflores- 

 cence composed of few scattered one-sided, often more or less curved, many-flowered sessile 

 spikes with the rachis sometimes conspicuously prolonged beyond the spikelets. Spikelets 

 numerous, 1-2-flowered, the lower flo\ver perfect, the upper one when present staminate or 

 sterile, crowded in 2 rows. Scales 3 or more, the 2 lower empty, narrow, acute, un- 

 equal, keeled, the third one enclosing a narrow hyaline palet and a perfect flower, usually 

 thinner and broader, 3-nerved, the nerves excurrent from the lobes or teeth as short pro- 

 jections or awns or protruding between the lobes, the small empty scales terminating the 

 rachilla 1-3, 3-awned. Stamens 3. Styles distinct. Stigmas plumose. MESQUITE GRASS. 

 Awns terminating the lobes of the flowering scale. 

 Stems glabrous. 



Rachilla of the spikelet with a dense tuft of long hairs at the apex. 1. B. oligostachya. 



Rachilla glabrous. 



Second empty scale with large hair-bearing tubercles on one or both sides 



of the rnidnerve. 2. B. hirsuta. 



Second empty scale glabrous and free of tubercles. 



Flowering scale pubescent with long ascending silky hairs. 3. B. Burkei. 



Flowering scale glabrous, or sometimes with a few hairs at the base. 4. B. trifida. 

 Stems densely villous below. 5. B. eriopoda. 



Awns arising between the lobes of the flowering scale. 6. B. microstachys. 



1. Bouteloua oligostachya (Nutt.) Torr. Stems 1.5-5 dm. tall, erect: leaf -blades 

 2-10 cm. long, 2 mm. wide or less, involute, at least at the long slender point : spikes 1-3, 

 2.5-5 cm. long, the rachis ending in a short inconspicuous tip : spikelets about 6 mm. long, 

 the rachilla with a tuft of long hairs under the rudimentary scales and awns. 



On prairies, Manitoba to Alberta, Wisconsin and Texas. Also in Mexico. Summer and fall. 



