CHLORIDEAE 



109 



1. Atheropogon curtipendulus (Michx.) Fourn. Tall 

 Grama. Common on dry and rocky mountain and hillsides 

 throughout the State, mainly in the Upper Sonoran Zone, but 

 extending into the Lower Sonoran and into the Transition. 



2. Atheropogon bromoides (H. B. K.) Occurs sparingly in 

 the southwestern corner of the State in the Upper Sonoran Zone. 



48. BOUTELOUA Lag. Grama Grasses. 



Plants annual. 

 Spike solitary; plant tufted, low. 

 Spikes more than one. 



Spikelets closely appressed to the rachis 



forming a cylindrical spike: plant tufted 



4 to 8 inches high. 



Spikelets crowded on one side of the 



rachis, making it one sided. 



Plant a foot high or more; stems erect; 



spikelets larger than in the next. 

 Plant 4 to 6 inches high, many stems and 

 widely spreading; spikelets small. 

 Plants perennial. 

 Spikes loose more or less cylindric; lower 



parts of stems densely woolly. 

 Spikes with more numerous crowded spike- 

 lets, one sided; lower parts of stems not 

 woolly. 

 Empty glumes smooth or slightly roughen- 

 ed. 

 Empty glumes stiff, hairy. 



Spikes 3 to 5, short and broad with con- 

 spicuous spreading hairs: rachis ex- 

 tending well beyond the end. 

 Spikes 1 to 3, mostly 2, longer and nar- 

 rower, frequently 1-2 inch long, not 

 so hairy; the rachis extending only 

 slightly. 



1. B. prostrata. 



2. B. aristidoides. 



3. B. vestita. 



4. B. polystachya. 



5. B. eriopoda. 



6. B. breviseta. 



7. B. hirsuta. 



S. B. oUgostachya. 



Bouteloua trifida is reported from New Mexico on the 

 strength of two specimens collected by Wright which probably came 

 from Texas. 



1. Bouteloua prostrata Lag. Moderately common in the 

 mountains; in the Transition Zone. Occasionally referred tO' as a 

 "six-weeks Grama." 



2. Bouteloua aristidoides Thrub. Six-weeks Grama. 



Common after the summer rains on the mesas of the southern part 



