Cynodoti. GRAMINEvE. 291 



* Strikes pectinatelif many-flowered, erect or spreading, the rhachis not prolonged 



beyond the spikelets. 



1. B. oligostachya, Torr. Perennial, to 18 inches high : leaves smooth or 

 barely roughened above : spikes 1 to 5, remote, 1 to 1^ inches long, often much 

 curved, on very short hairy pedicels ; rhachis smooth or sparingly hairy : spikelets 

 (including setae) about 3 lines long : glumes (the upper 2 lines long) strongly keeled, 

 with a few minute hairy papillae : lower palet equalling the upper glume, copiously 

 hairy on the back, its long middle lobe 2-cleft ; central seta longest (a line long) ; 

 upper palet equalling the lower, with lateral tufts of long hairs at base : pedicel of 

 sterile floret about a line long, hairy at top and bearing a rudimentary hooded palet 

 and 3 very short awns. Gray, Man. 621. Atheropogon oligostachyum, Nutt. Gen. 

 i. 78. Chondrosium oligostachyum, Torr. in Marcy Rep. 300. 



Summit of Providence Mountain, Cooper. This species, which extends from Wisconsin west- 

 ward, is common in Nebraska and southwestward to Northern Mexico. The specimens from Dr. 

 Cooper, who alone seems to have met with it in California, are only 6 inches high. 



2. B. polystachya, Torr. Culms 3 to 15 inches long : leaves scabrous, often 

 with a few hairy papillae on the margins and midnerve ; sheaths loose : spikes 3 to 6 

 or more, | to 1 inch long, rarely slightly curved, the scabrous rhachis hispid-ciliate : 

 spikelets about 2 lines long : glumes often irregularly 2-toothed, the upper broadly 

 ovate, a line long, rough-pubescent, short-awned below the apex : lower palet very 

 hairy on the nerves below, otherwise smooth and shining, the central lobe rather 

 obtusely bifid, the lateral narrow and acute ; lateral setae stoutest and longest ; upper 

 palet equalling the lower, silky-hairy on the margins and on each side at base : im- 

 perfect floret of 2 small (mostly) hooded palets and 3 setae, upon a hairy pedicel which 

 also bears a very minute rudimentary third floret. Pacif. E. Rep. v. 366, t. 10. 

 Chondrosium polystacht/um, Benth. Bot. Sulph. 56; Torr. in Emory Rep. 153. B. 

 pumila, Buckl. Proc. Acad. Phil. 1862, 93. 



Fort Mohave (Cooper) ; Colorado River (A. Schott), and eastward ; very common in the Rio 

 Grande region and southward. Varying from nearly prostrate to erect with very slender culms ; 

 the spikes generally dark purple and the foliage more or less tinged. The seta; of the lower palet 

 also vary considerably in length, and sometimes the imperfect floret has a broad cordate palet 

 awued between the lobes, and the second imperfect floret becomes more conspicuous. 



* * Spikes short, few-flowered, at length reflexed : point of rhachis prolonged. 



3. B. aristidoid.es. Culms 6 to 18 inches high, branched above : leaves soon 

 involute, scabrous above, margins with scattered 1 -haired papillae ; sheaths very loose, 

 smooth except a hairy tuft at throat on each side : spikes 4 to 8, distant, secund, 

 8 to 10 lines long, on white-hairy pedicels 2 lines long; rhachis scabrous, the tri- 

 quetrous point equalling the terminal spikelet : spikelets 3, distant, appressed, about 

 3 lines long; lower glume almost setiform, the upper subulate, strongly keeled, some- 

 times 3-toothed : perfect floret with a slightly bearded callus ; lower palet coriaceous, 

 silky-pubescent on the nerves, minutely punctulate, nearly equalled by the upper : 

 imperfect flower on a short pedicel slightly hairy at top, of 3 unequal awns, one 

 3 lines long, the shorter slightly dilated below. Dinebra aristidoides, HBK. Nov. 

 Gen. i. 171, t. 695. Eutriana aristidoides, Kunth, Enum. i. 280, and Suppl. 233. 



Fort Yuma (Major Thomas) ; San Diego County, Palmer. Common in Arizona and Mexico. 

 Apparently monoearpic, the cluster of withered sheaths at the base indicating that it takes a rest 

 and completes its growth the second season. The young plant, with its spikes erect and appressed, 

 presents a strikingly different appearance from the old one, when its fully developed spikes are 

 refracted. The long awns to the sterile floret give it so strong a resemblance to an Aristida that 

 the specific name is especially descriptive. 



29. CYNODON, Richard. DOG'S-TOOTH GRASS. 



Inflorescence in several one-sided flattened spikes which are digitate at the end of 

 the peduncle. Spikelets 1 -flowered, with a rudiment consisting of a naked pedicel 



