790 . OBDBB 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. 11 Common in wet 

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

 . . whitish down. Jl. 



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

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

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

 pedicellate ; palese 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 ns long as the pales. Awns long or short Nos. 2, 3 



1 A. atropurpurea 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, 

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



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

 . 1i 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. U Swamps, N. States and Can. May. (A. aristulata Torr.) 



27. DANTHO'NIA, DC. (In honor of M. Danthoine, a French botan- 

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

 spikelet of flowers, cuspidate ; palese 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 Ivs. 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.) 



28. 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. 



f ARRIIENATHERUM. Gls. unequal, 2-flowered, with a rudiment ; lower fl. stmninate.No. 1 

 | AIROPS1S. (1 Is. Kubrqunl, 2-flowered, with no rudiment, fls. both perfect. Dwarf. . . . . No. 2 

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



1 A elatior L. Culm 2 Af, geniculate, smooth ; Ivs. lance-linear, rough oa the 

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

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

 mostly awuless. it A tall grass, introduced and naturalized in cultivated 

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



2 A. preecox Beauv. Csespitous; 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 tho back twice its length. (1) N. Y. to Yirg. Jn. (Aira, L.) 



3 A. sativa L. CoirsioxOAT. Culm smooth, 2 4fhigh; Ivs. linear-lanceolate, 

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

 pedunculate, pendulous, 2-flowered, both flowers perfect, the lower one mostly 

 awned 5 palfce somewhat cartilaginous, closely embracing the caryopsis. GD A 



