ORDER 156. GRAMINE^E. 



sheaths striate ; pan. oblong, dense, -whitish, with a >purple tinge ; fls. shorter than 

 the glumes; sterile one with a recurved, included awn. if Common in wet 

 meadows, N. Eng., to the uplands of Ga. A beautiful grass, very soft with 

 whitish down. Jl. 



26. AI X RA, L. (Gr. alpa, a deadly weapon ; originally applied to a 

 poisonous grass.) Spikelets . 2-flowered, without abortive rudiments ; 

 glumes 2, membranaceous and shining, subequal ; one of the flowers 

 pedicellate ; paleae subequal, pilous at base, the lower one lacerate at 

 apex and awned on the back. Fls. in panicles of a silvery purplish 

 hue. 



Glumes much longer than the pales. Awns long No. 1 



Glumes about as long as the pales. Awns long or short Stak' 2, 8 



1 A. atropnrpurea "WahL Caespitous, a foot high; culms very slender; Ivs. 

 flat ; pan. thin, with spreading branches ; glumes much longer than the flowers ; 

 pales hairy at apex. High Mts. of N. Eng. and N. Y. Aug. 



2 A. flexuosa L. Culm smooth, 1 2f high, nearly naked; Ivs. setaceous, 

 smooth, with striate sheaths and truncate stipules ; pan. loose, spreading, trichoto- 

 mous, with long, flexuous branches ; awns geniculate, twice longer than the pales. 

 If Vales and hills, U. S. and Brit. Am., common. An erect, elegant grass, 

 growing in tufts. Jn. 



3 A. caespitosa L. Caespitous, glabrous ; st. 18 30' high ; Ivs. narrow-linear, 

 scabrous above, smooth beneath, flat ; panicle pyramidal, capillary, oblong, finally 

 diffuse ; awns straight, about as long as the pales, which are longer than the bluish 

 glumes. 2f Swamps, N. States and Can. May. (A. aristulata Torr.) 



27. DAN1WNIA, DC. (In honor of M. Danthoine, a French botan- 

 ist.) Spikelets 2 7 -flowered; glumes 2, subequal, longer than the 

 spikelet of flowers, cuspidate ; palea3 hairy at the base, lower one bi- 

 dentate at the apex, with a twisted awn between the teeth, the upper 

 one obtuse, entire. 



D. spicata Beauv. St. slender, nearly erect, 12 18' high, tower Its. numerous. 

 4 6' long, flat, hairy above, cauline Ivs. much shorter, subulate, erect, on very 

 short sheaths; panicle simple, spicate, short, erect; spikelets 3 8 or 10, about 7- 

 flowered; glumes a little longer than the flowers ; lower palea hairy, about half as 

 long as its spirally twisted awn. Pastures and open woods, common. June 

 Aug. (Avena, L.) 



^8. AVE V NA, L. OAT. Spikelet 2 to 5-flowered ; glumes 2, loose 

 and membranous, awnless, often as long as the pales ; pales 2, herba- 

 ceous, at length subcoriaceous, the lower one bifid and usually with a 

 twisted or bent awn at the back. Fls. paniculate. 



ARBHENATHEBUM. Gls. unequal, 2-flo\vered, with a rudiment; lower fl. staminate.No. 1 



$ AlliOPSIS. Gls. subequal, 2-flowered, with no rudiment, fls. both perfect. Dwarf. No. 2 



AVENA proper. Gls. equal, longer than the 2 fls., and strongly striate. Cultivated No. 3 



1 A. elatior L. Culm 2 4f, geniculate, smooth ; Ivs. lance-linear, rough on the 

 margin and upper surface ; panicle loose, equal, nodding, branches in pairs or ter- 

 iiate ; spikelets 2-flowered ; awn twice as long as the palea ; upper flower $ , 

 mostly awnless. If A tall grass, introduced and naturalized in cultivated 

 grounds. May, June. (Arrhenatherum avenaceum Beauv.) 



2 A. pr&cox Beauv. Ca?spitous; culm erect, a few inches high; Ivs. % 1' 

 long, rough; sheaths deeply striate; panicle dense, racemous; spikelets ovate, 2- 

 flowered, glumes as long as the flowers ; lower palea with a bent awn from the 

 lower part of the back twice its length. (1) X. Y. to Virg. Jn. (Aira, L.) 



3 A. sativaL. COMMON OAT. Culm smooth, 2 4fhigh; Ivs. linear-lanceolate, 

 veined, rough, with loose, striate sheaths ; slip, lacerate ; panicle loose ; spikelets 

 pedunculate, pendulous, 2-flo\vered, both flowers perfect, the lower one mostly 

 awned ; palea somewhat cartilaginous, closely embracing the caryopsis. (D A 



