No. 34. 



BOUTELOUA. 



The genus Bouteloua, which includes those grasses popularly called grama grass, 

 is a very large one in the Southwest, embracing many species, both annuals and 

 perennials. They are nearly all nutritious and valuable for pasturage. The gen- 

 eral characters of the inflorescence are as follows : 1 or several-flowered spikes 

 single at the apex of the culm, or several disposed in a raceme ; these spikes 

 closely crowded or loosely imbricated with spikelets arranged on one side of 

 the rachis in 2 rows ; spikelets usually consisting of 1 perfect flower and a 

 pedicel (bearing 1 to 3 stiff awns, and usually a few imperfect glumes with the 

 awns) ; one or two additional imperfect flowers rarely present in the spikelet ; 

 flowering glumes variously lobed at the apex, lobes terminating with awns. The 

 several species present a great diversity in the details of these general features. 



BOUTELOUA ARENOSA Vasey. 



Plant annual. Roots few, fibrous. 



Culms in tufts, erect or decumbent, simple or geniculate and branching below, 

 slender, 6 to 10 inches long. 



Leaves sparse ; sheath loose, shorter than the internode, striate ; ligule conspicu- 

 ous, strongly ciliate ; blade i to 1 line wide, 1 to 2 inches long, long-acuminate. 



Panicle 2 to 2-g- inches long, composed of 3 or 4, mostly one-sided sessile 

 spikes, | to f inches long, erect, or somewhat recurved, consisting of about 20 

 spikelets arranged alternately on the narrow flattened rachis. 



Spikelets imbricated, each with 1 perfect and 1 rudimentary flower, about 

 3 lines long including the awns. 



Empty glumes thin, smooth, 1-nerved, oblong-lanceolate, 1 to L| lines long, 

 upper usually the longer, both acute and sometimes toothed at the apex and ter- 

 minated with a short awn ; flowering glume woolly externally, dividing into 2 

 lateral and 1 central awn, body about 1 line long, extending into 2 narrow 

 teeth or lobes rather shorter than the awns, lateral awns nearly 2 lines long, cen- 

 tral one somewhat shorter. 



Palet narrower than its glume, 2- to 4-toothed, 2-nerved, nerves extended into 

 awns. Imperfect flower inclosed by the flowering glume, consisting of 3 long 

 awns at the summit of a short hairy pedicel, 2 of the awns having each a rudi- 

 mentary scale at the base. 



Plate XXXIV; a, spikelet enlarged ; b, empty glumes; c, flowering glume; 

 d, palet ; e, imperfect flower. 



The specimens were from loose sandy soil, at Guaymas on the Gulf of California. 



