Dh AGiiUS'ilDEAE 



Stems more slender and weaker; 

 panioie laxly spreading; pedi- 

 cels very slender and often 

 cuived. 12. .1. puriJitit'j. 



1. Aristida Bromoides 1 1. B. K. A cummon "six weeks'' 

 grasb on llu- luesas" and lu some extent in the fields after the 

 summer rains, in the southern part of the State, in the Lower 

 Sonuran Zone. 



2. Aristida divaricata llumb. and Bonph. A fairly common 

 widely branching- needle grass in the sand hills and mesas in the 

 the southern part of the State, sometimes in the drier foothills; in 

 the Sonoran Zones. 



3. Aristida SCtliediana Triu. and Rupr. Usually found along 

 with ihe jneceding species, which it closely resembles, except for 

 the difference in the awns. 



4. Aristida arizonica Vasey. One of the largest of ihe 

 "needle grasses," coming into the west side of the State from 

 Ai-izona. In the Sonoran Zones. 



5. Aristida havardii Vasey. in the foothills and on the 

 mesas of the southern part of the State, in the Sonoran Zones. A 

 low spreading grass 6 to 10 inches high. 



6. Aristida !ongiseta Stcud. The Long-awned Needle- 

 grass is the most easily recognized of all. It forms a close tuft 

 with erect slender stems from a bunch of curling leaves: the awns 

 are often .'J inches long or more and j)iirj)lisli tinged. On the plains 

 -and mesas llirouglioiit the State below the yellow pine zone. 



7. Aristida vaseyi Woot. and stand, in the rocky foothills 

 of the low ini.unlains im the mesas of the southern part of the 

 State; in (he Lower Sonoran Zone. 



8. Aristida micrantha (Vasey) Nash. A western Texas 

 species which comes into the southeastern corner of the State. Lower 

 Sonoran Zone. 



9. Aristida n. sp. So tar known only from the southern 

 part of the Stale on Tortugas Mouiilain near the Agricultural 

 College. Lower Sonoran Zone. 



