MANUAL OF THE GRASSES OF THE UNITED STATES 511 



1. Trichloris mendocina (Phil.) Kurtz. (Fig. 1079, A.) Culms 

 40 to 100 cm tall; blades 2 to 4 mm wide ; inflorescence dense, feathery, 

 the spikes 5 to 10 cm long; spikelets crowded; fertile lemma about 3 

 mm long, the second lemma much reduced, both with delicate awns 

 about 1 cm long. % — Plains, canyons, and rocky hills, western 

 Texas to Arizona and northern Mexico; southern South America. 

 Rarely cultivated for ornament (as T. blanchardiana Fourn.). 



2. trichloris pluriflora Fourn. ^ (Fig. 1079, B.) Culms 50 to 100 

 cm tall; blades 5 to 10 mm wide; inflorescence looser and less feathery 

 than in T. mendocina; spikes 7 to 15 cm long; fertile lemma about 4 

 mm long, the others successively shorter, the middle awns of all 5 to 

 15 mm long, somewhat spreading, the lateral awns short or obsolete. 

 21 — Plains and dry woods, southern Texas and Mexico ; southern 

 South America. 



104. BOUTELOUA Lag. Grama 



Spikelets 1 -flowered, with the rudiments of one or more florets 

 above, sessile, in two rows along one side of the rachis; glumes 1- 

 nerved, acuminate or awn-tipped, the first shorter and narrower; 

 lemma as long as the second glume or a little longer, 3-nerved, the 

 nerves extending into short awns or mucros, the internerves usually 

 extending into lobes or teeth; palea sometimes 2-awned; rudiment 

 various, usually 3-awned, the awns usually longer than those of the 

 fertile lemma, a second rudimentary floret sometimes present. Peren- 

 nial or sometimes annual, low or rather tall grasses, with two to several 

 or many spikes racemose on a common axis, or sometimes solitary, 

 the spikelets few to many in each spike, rarely solitary, pectinate 

 or more loosely arranged and appressed, the rachis of the spike usually 

 naked at the tip. The sterile florets forming the rudiment are variable 

 in all the species and commonly in individual specimens. The general 

 pattern of rudiment is fairly constant for each species, the variability 

 being in the reduction or increase in number and size of the sterile 

 florets, the reduction from 3 awns to 1, and in the amount of pubes- 

 cence. Type species, Bouteloua racemosa Lag. (B. curtipendula). 

 Named for the brothers Boutelou, Claudio, and Esteban. The genus 

 was originally published as Botelua. 



The many species are among our most valuable forage grasses, 

 forming an important part of the grazing on the western ranges. 

 B. gracilis , blue grama, and B. hirsuta, hairy grama, are prominent 

 in "short grass" regions of the Great Plains; B. eriopoda, black 

 grama, and B. rothrockii, Rothrock grama, are prominent in Arizona. 

 Two annuals, B. barbata and B. parryi, form a part of the sixweeks 

 grasses of the Southwest ; B. curtipendula is widely distributed and is 

 much used for grazing and for hay; B. trifida is important from Texas 

 to Arizona. 



Spikelets not pectinately arranged (except in B. chondrosioides) , the spikes falling 

 entire at maturity Section 1. Atheropogon. 



Spikelets pectinately arranged, the spikes persistent, the florets falling from the 

 persistent glumes Section 2. Chrondrosium. 



Section 1. Atheropogon 



Plants annual 1. B. aristidoides. 



Plants perennial. 



Spikes usually 20 to 50; awns short, inconspicuous. 



Spikes of 1 or 2 spikelets; culms very slender 2. B. uniflora. 



Spikes of few to several spikelets; culms mostly stouter. 



3. B. curtipendula. 



55974°— 35 33 



