WOOTON AND STANDLEY FLORA OF NEW MEXICO. 63 



Spikelete small, 10 mm. long or less, the awns 

 never more than twice as long as the lemma. 

 Panicle strict, congested, never spreading... 7. A. vaseyi. 

 Panicle spreading, at least in age. 



Panicles always spreading, the pedicels 

 very weak and sinuous; awns 



merely spreading 8. A. micrantha. 



Panicles at first congested, finally spread- 

 ing, the pedicels rigid, straight, 

 ascending; awns Btrongly diver- 

 gent 9. A. pansa. 



Spikelets large, 15 mm. long or more, the awns 

 usually more than twice as long as the 

 lemma. 

 Panicles simple or nearly so. 



Panicles strict, the spikelets numerous 

 and congested, relatively small; 



pedicels short 7. A. vaseyi. 



Panicles lax, the spikelets few, scattered, 

 about 15 mm. long; pedicels elon- 

 gated 10. A.fendleriana. 



Panicles compound. 



Culms stout; panicles rigidly erect; pedi- 

 cels straight 11. A. wrightii. 



Culms weaker and more slender; panicles 

 laxly spreading; pedicels very 

 slender, often curved 12. A. purpurea. 



1. Aristida bromoides H. B. K. Nov. Gen. & Sp. 1: 122. 1816. 



Six-weeks needle grass. 



Type locality: "In montibus regni Quitensis, juxta Tambo de Guamote et 

 Llanos de Tiocaxas, alt. 1,600 hexap." 



Range: Texas and Arizona to Mexico; also in South America. 



New Mexico: Santa Fe; Cross L Ranch; Cerrillos; Chama River; Algodones; 

 Socorro; Mangas Springs; Black Range; Deming; Dona Ana and Organ mountains; 

 White Sands; White Mountains; Guadalupe Mountains; Knowles; Roswell. Dry 

 plains and hills, in the Lower and Upper Sonoran zones. 



2. Aristida divaricata Humb. & Bonpl.; Willd. Enuni. PI. 99. 1809. 



Aristida humboldtiana Trin. & Rupr. Mem. Acad. St. P6tereb. VI. Sci. Nat. 5 1 : 118. 

 1842. 



Type locality: "Habitat in Mexico." 



Range: Arizona and western Texas to Mexico. 



New Mexico: Cross L Ranch; Texline; Gallinas Mountains; Black Range; Deming*, 

 Dona Ana and Organ mountains; Eagle Creek; Lake Arthur. Dry plains and hills, 

 in the Lower and Upper Sonoran zones. 



3. Aristida schiediana Trin. & Rupr. Mem. Acad. St. IVtersb. VI. Sci. Nat. 5': 



120. 1842. 

 Aristida divergens Vaeey, Contr. U. S. Nat. Herb. 3: 48. 1892. 

 Type locality: "Mexico: prope Jalapam." 

 Range: Arizona and western Texas to Mexico. 



New Mexico: Socorro; Beat Mountain; Copper Mines; i ir^iii Mountains; plains 

 south of Roswell. Upper Sonoran Zone. 



