Panicum obtusum H. B. K. Nov. Gen. et Sp. PI. 1: !>8. 1815. 



Tucson, N..S. 1514, 1546; Benson, No. 2006; near Pearce, No. 1935; Sulphur Spring 

 Valley, No. 1645 R. H. Forl^es, October, 1900. 



Panicum sang-uinale Linn. Sp. PI. 57. 1753. {Si/afherisma ><aaijidnalis Nash.) 



University grounds, Tucson, No. 1517. 



Panicum saccharatum Buckl. Prel. Rept. Geol. and Agrl. Snrv. Tex. App. 2. 

 1866. {P. larhniiiithniiiToYV. 1857, not Hochst. 1855.) 



Near Pearce, No. 1942; Benson, No. 1997; Fort Lowell, No. 1572; Dragoon Moun- 

 tains, No. 1871; Rincon Mountains, No. 1782. 



Chgetochloa composita (H. B. K.) Scribn. U. S. Dept. Agr. Div. Agros. Bui. 

 4:39. 1897— Scribn. & Merrill, ibid. BuL 21:27. 1900. {Setaria composUa 



H. B. K.) 



Benson, No. 2003; Tucson, No. 1511, small form. 



Cheetochloa grisebachii (Fourn.) Scribn. 1. c— Scri])n. & Merrill,!, c. 35. {Setaria 



gvi.sebiiddi Fourn. ) 

 Common in sandy soil, Sulphur Spring Valley, Wilcox to Cochise, No. 1901. 

 ChEetochloa macrostachya (H. B. K. ) Scrilm. & Merrill, U. S. Dept. Agr. Div. 



Agros. Bui. 21:29. 1900. {Sdarla macrostachya H. B. K.) 

 Near Pearce, No. 1944. 

 Chgetochloa viridis (Linn.) Scribn. U. S. Dept. Agr. Div. Agros. Bui. 4:39. 



1897. {Panicum viride Linn.; Setaria viridis Beauv.) 

 University grounds, Tucson, No. 1526. 



Cenchrus montanus Nees in Royle, 111. Bot. Himal. 416. 1839. 

 University grounds, Tucson, No. 1530. Introduced from Asia. 



Cenchrus tribuloides Linn. Sp. PL 1050. 1753. 



Fort Lowell, No. 1560. 



Aristida sequiramea Scheele, Linntea, 22 : 343. 1849. 



Cochise, No. 1880. 



Aristida wquiramea Scheele has been variously referred to A. purpurea Nutt., .1. 

 fendkriana Steud., A. loiigiseta Steud., and A.fasciculata Torr., 1)ut is a very dis- 

 tinct species. It is most closely related to .1 ristida purpurea Nutt. , but is readily 

 distinguished by its usually larger size, larger spikelets, shorter empty glumes, 

 and especially by its very strongly tul)erculate-hispid flowering glumes. No. 

 1880 Grithths, cited above, differs from typical A. wquiramea in having nearly 

 awnless empty glumes. 



Aristida americana Linn. Amcen. Acad. 5 : 393. 1760. {Aristida fasciculatu Torr. 

 Ann. Lye. N. Y. 1 : 154. 1824; Aristida dispersa Trin. & Rupr. Agrost. 3 : 129. 

 1842.) 



LTniversity grounds, Tucson, No. 1528. 



From a careful study of the synonymy of this species, it is evident that Aristida 

 americana Linn, is the correct name for this species. 



ARISTIDA AMERICANA BROMOIDES (H. B. K.) Scribn. & Merrill, n. comb. 

 {Aristida hrumuidcs II. B. K. N<jv. Gen. et Sp. PI. 1 : 122. 1815.) 



Benson, No. 1835; Rincon Mountains, No. 1808; Pearce, No. 1926; Sulphur Spring Val- 

 ley, 1632 R. H. Forbes, October, 1900. 



This is the common, low, csespitose form of the species, and scarcely worthy of spe- 

 cific rank. 



Aristida divaricata Humb. (k Bonpl. in Willd. Enum. 99. 1809. 



:yiescal, No. 1816. 



Aristida divergens Vasey, Contr. U.S. Nat. Herl). 3:48. 1892. {A. schiediana 



minor Vasey.) 

 Dragoon Mountains, No. 1872; near Pearce, No. 1838. 



