136 



GBAMINEAE 



B. curtipendula. 

 B. aristidoides. 



Rachilla prolonged beyond the perfect floret and bearing a sterile (rarely stam- 

 inate) floret, a second or third rudiment often present. Lemma broader, 3 to 

 5-nerved, 2 to 4-toothed or cleft, usually awned between the teeth. Palea about 

 as long as the lemma, bidentate, the 2 keels scabrous. Sterile floret sometimes 

 reduced to awns, rarely obsolete. Annuals or usually perennials with narrow 

 blades and few or numerous short spikes scattered along a common axis. 

 Species about 30, all American, mostly of the Mexican plateau. (The brothers 

 Claudio and Esteban Boutelou, Spanish gardeners.) 

 Spikes containing 1 to 3 spikelets, numerous along a main axis. 



Plants perennial 1. 



Plants annual 2. 



Spikes usually few, containing numerous spikelets. 

 Plants annual. 



Awns about 1^ lines long; spikes 2 to 4 ' 3. B. arenosa. 



Awns barely protruding ; spikes 4 to 6 or more 4. B. barbata. 



Plants perennial. 

 Spikes several. 



Spikes narrow, strictly 1-sided; spikelets numerous 5. B. rothrockii. 



Spikes broad, loose, irregularly 1-sided; spikelets few 6. B. radicosa. 



Spikes usually 1 to 3. 



Rachis not prominently produced; glumes sparsely hairy 7. B. gracilis. 



Rachis produced beyond the spikelets as a naked point; glumes prominently papillose- 

 hispid 8. B. hirsuta. 



1. B. curtipendula Torr. Perennial; culms erect, 1 to 4 feet high; spikes 

 numerous on an elongated rachis, ^ to % inch long, reflexed, mostly turned to 

 one side ; glumes narrow, acuminate, scabrous on keel and somewhat so on the 

 back, the second about 2~y 2 lines long; lemma as long as second glume, ovate- 

 lanceolate, 3-nerved, scabrous toward tip, 3-toothed, the palea about as long; 

 rudiment as long as lemma, 4-lobed, 3-awned between the lobes, the lateral 

 lobes and awns shorter. 



Plains and rocky hills, Montana and Ontario, south to Mexico. 

 Loc. Santa Rosa Mt., San Jacinto Range, Hall 2138. 



Refs. BOUTELOUA CURTIPENDULA Torr. in Emory, Mil. Reconn. 154. 1848. Chloris cur- 

 tipendula Miehx. Fl. Bor. Am. 1: 59. 1803. Bouteloua racemosa Lag. Var. Ciene. 2*: 141. 1805. 



2. B. aristidoides Griseb. Annual ; culms spreading, slender, 6 to 15 inch* 

 high ; spikes several, slender, about ^ inch long, the 1 to 3 spikelets distant 

 appressed to the rachis, the latter ending in a slender naked point; glume 

 narrow, acuminate, the first % as long as the second; lemma narrowly lancec 

 late, 3-nerved, the nerves pilose, the lateral ending in awned teeth as long as 

 the central acuminate point; rudiment consisting of a pilose pedicel and 3 

 awns longer than the spikelet. 



Open ground, deserts and foothills, southern California to western Texas and 

 south into South America. San Diego, Orcutt in 1890; Colorado Desert, Bran- 

 degee in 1905 ; Colorado River, Riverside Co., Hall 5962. 



Refs. BOUTELOUA ARISTIDOIDES Griseb. Fl. Brit. W. Ind. 537. 1864; Thurb. in Wats. Bot. 

 Cal. 2 : 291. 1880. Dinebra aristidoides H.B.K. Nov. Gen. & Sp. 1 : 171. 1816. 



3. B. arenosa Vasey. Annual ; culms spreading or prostrate, about 6 inches 

 long; spikes 2 to 4, many-flowered, about y 2 inch long; glumes 1-nerved, the 

 first 1 line, the second 1% lines long; lemma a little shorter than the second 

 glume, pilose below, 4-lobed, the lateral lobes short, 3-awned from between the 

 lobes, the awns about 1% lines long; palea 4-toothed, 2-awned; rudiment l /2 

 line long, triangular-truncate, pilose at base, 4-lobed, with 3 long awns betwee 

 the lobes. 



