130 MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 



14. Aristida longiseta Steud., Syn. PL Glum. 1: 420. 1855. 

 Apache, Navajo, Coconino, Mohave, Yavapai, Greenlee, Graham, 



and Pima Counties, 3,000 to 5,000 feet, dry hills and plains, April to 

 October. Texas to Colorado and Arizona. 



Two varieties are recognized, var. rari flora Hitchc, which differs in 

 the few-flowered panicles with long capillary flexuous branches; and 

 var. robusta Merr., which differs in being a larger plant with a rather 

 dense panicle, the branches relatively short and stiffly ascending. The 

 former has been collected in Yavapai, Cochise, and Pima Counties, 

 and the latter in Coconino, Mohave, and Pima Counties. 



15. Aristida wrightii Nash in Small, Fl. Southeast. U. S. 116. 1903. 

 Mohave, Pinal, Maricopa, Santa Cruz, and Pima Counties, 1,000 



to 5,000 feet, dry plains and rocky slopes, flowering apparently when- 

 ever conditions are favorable. Texas, Colorado, and Utah, to south- 

 ern California and central Mexico. 



16. Aristida arizonica Yasey, Torrey Bot. Club Bui. 13: 27. 1886. 

 Navajo, Coconino, and Cochise Counties, 4,500 to 8,000 feet, dry 



plains, rocky slopes, and open woods, May to September, type from 

 Arizona {Rushy 875). Colorado and western Texas to Arizona, and 

 southward through Mexico. 



17. Aristida parishii Hitchc, in Jepson, Fl. Calif. 1: 101. 1912. 

 Yavapai, Maricopa, Yuma, and Pima Counties, 1,500 to 4,000 feet, 



dry rocky hills, February to May. Arizona and southern California, 



46. TRAGUS. Burgrass 



Low annuals with flat leaf blades, the spikes closely arranged on a 

 slender axis; spikes subsessile, falling entire, composed of 2 to 5 spikelets 

 on a short zigzag rachis; first glumes small or wanting, the second 

 glumes of the 2 lower spikelets bearing stout hooked spines along each 

 side; lemma and palea thin, the lemma flat, the palea convex. 



Key to the species 



1. Spikes or burs subsessile; spikelets 2 to 3 mm. long, scarcely exceeding the 

 spines 1. T. berteronianus. 



1. Spikes or burs pedicelled; spikelets 4 to 5 mm. long, projecting beyond the 

 spines 2. T. racemosus. 



1. Tragus berteronianus Schult,, Mant. 2: 205. 1824. 



Nazia aliena Scribn., U. S. Dept, Agr. ; Div. Agrost. Bui. 17: 

 28. 1899. 



Mohave, Pinal, Cochise, Santa Cruz, and Pima Counties, up to 

 5,500 feet, dry open ground, September to October. Texas to Arizona, 

 south to Argentina; warmer parts of the Old World. 



2. Tragus racemosus (L.) All., Fl. Pedem. 2: 241. 1785. 



Cenchrus racemosus L., Sp. PL 1049. 1753. 



Nazia racemosa Kuntze, Rev. Gen. PI. 2: 780. 1891. 



On campus of the University of Arizona (Pima County). Waste 

 ground, occasionally from Maine to North Carolina, also Texas to 

 Arizona; introduced from the Old World. 



