GRIFFITHS THE GRAMA GRASSES. 385 



California: Jones 67a, Needles. 



New Mexico: Wooton 2923, north of Chamita; 2023, Las Cruces; 3063, Organ Moun- 

 tains; 398, Dona Ana County. Metcalfe 701, Silver City; 1395, Black Range. 

 Earle 296, Roswell. Plank 15, Socorro. Lemmon 3147, Holbrook to Albuquerque. 

 Hitchcock 3806, Organ Mountains. Jones 55a; Tracy 8190, Carlsbad. Mearns 

 2363, Dog Spring, Dog Mountains. Mulford 69, Florida Mountains. 



Nevada: Cooper 2241, Fort Mojave. 



Texas: Palmer 1356, Guadalupe; Tracy 8217, Big Springs; 8207, Fort Worth; Coclerell 

 15, Fort Bliss. Jones 641, 13a, and 4341, El Paso. Havard in 1882, Eagle Pass. 

 Nealley 103, Laredo. 



Utah: Jones 5702a, Junction; 5696, Cainville; 5652, Capitol Wash. Thompson 339. 



Mexico: Brandgee, San Jose del Cabo, Lower California. Palmer 508, La Paz, Lower 

 California and Guaymas; 857, Carmen Island; 714, Durango; 400 and 401, Saltillo. 

 Schaffner 152 and 1017, San Luis Potosi; 153, Valley of Mexico. Pringle 490, 

 Chihuahua; 11216 and 13626, Jimulco. Barclay, Lower California. Parry & 

 Palmer 946, San Luis Potosi. Smith 957, San Antonio Valley, Oaxaca. Pittier 

 470, State of Durango. 



12. Bouteloua arenosa Vasey. 



Bouteloua arenosa Vasey, IT. S. Dept. Agr. Div. Bot. Bull. 12 1 : pi. 34 a . 1890. The 

 first use of the name was by Watson, b but no description is given. The type is Palmer 

 189, Guaymas, Sonora, Mexico, 1887, in the National Herbarium. 



DESCRIPTION. 



A tufted, smooth, erect or decumbent annual, with sparingly branched, simple or 

 geniculate culms, 10 to 15 cm. long; sheaths striate, rather loose, especially in branch- 

 ing individuals, the ligule conspicuous, consisting of a white, ciliate fringe 1 to 1.5 

 mm. long; blades 3 to 4 cm. long, rather sparse in the majority of specimens, but 

 plentiful in others; panicle racemose, 3 to 6 cm. long; spikes 2 to 4, about 1.5 cm. 

 long, mostly recurved; spikelets 16 to 20, pectinate, consisting of a lower perfect 

 floret and an upper rudiment; first glume 1 to 1.7 mm., the second about 3 mm. long, 

 the keels very minutely scabrous, usually 2-toothed with shori awns between the 

 teeth; lemma 4-toothed, about 4.5 mm. long including the 3 ling, scabrous, equal 

 awns, about 3 mm. long, completely covered on the back with long, white hairs 

 1 mm. or more in length; palet 4-toothed, 3 mm. long, including the scabrous awns, 

 about 1.3 mm. long, with a white, hairy, ciliate fringe outside of the nerves, the 

 awns being a continuation of these; rudiment 5 mm. long, consisting of three approxi- 

 mately equal, scabrous awns, 3 mm. long, alternating with the obovate lobes of the 

 lemma and supported upon a short, hairy-tufted stipe; caryopsis obovate, 1 mm. 

 long, 0.4 mm. wide, the scutellum covering about two-thirds of the ventral surface. 

 (Figure 40.) 



The species is to be looked upon as a long-awned form of B. barbata, which appears 

 to be characteristic of the coast of Sonora. Dr. Palmer's notes indicate that the 

 type was. collected in loose, sandy soil. 



It is quite doubtful in my mind whether B. arenosa is really specifically distinct 

 from B. barbata, but I hesitate to reduce it, because my experience in the field in 

 this particular locality is very limited. It must be confessed, however, that there 

 are forms of B. barbata in Arizona and New Mexico which approach this in the one 

 character which has served to separate it; that is, the length of the awns. However, 

 only the specimens enumerated below have awns as short as those of B. barbata, the 

 Arizona forms referred to B. barbata having awns only two-thirds to three-fourths as 

 long. We have here the same sort of differences that we have in B. rothrockii and 

 its allies. 



a The figure is very misleading. & Proc. Amer. Acad. 24 : 81. 1889. 



