AGROSTIDEAE 75 



17. Muhlenbergia porteri Scribn. Mesquite Grass — not 

 Vine Mesquite nor Texas Mesquite. On the mesas and low moun- 

 tains of the southern part of the State; in the Lower Sonoran Zone. 



18. Muhlenbergia pungens Thurb. On sand dunes at various 

 places throughout the State, in the Sonoran Zones. 



19. Muhlenbergia gracillima Torr. On the higher plains or 

 in the mountains at the southern end of the State: in the Upper 

 Sonoran or sometimes low down in the Transition Zone. 



20. Muhlenbergia arenlcola Bucki. On sandy soils in 



the southern part of the State ; in the Sonoran Zones. 



21. Muhlenbergia berlandieri Trin. Known only from a single 

 collection in the southwestern corner of the State. 



