790 Order 156.— GRAMINE^. 



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

 the glumes; sterile one -with a recurved, included awn. — 1i 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. cupa, 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 Nos. 2, 3 



1 A. atropurpurea "Wahl. Cyespitous, a foot high ; culms very slender ; lvs. 

 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; lvs. setaceous, 

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

 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. caespitdsa L. Csespitous, glabrous ; st. 18 — 30' high ; lvs. 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. — If Swamps, N. States and Can. May. (A. aristulata Torr.) 



27. DANTHCTNIA, DC. (In honor of Ml Danthoinc, a French botan- 

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

 spikelet of flowers, cuspidate ; palea) 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 lvs. numerous, 

 4 — 6' long, flat, hairy above, cauline lvs. 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. AVENA, 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. 



§ ARRHENATHEEUM. Gls. unequal, 2-flowered, with a rudiment; lower fl. staminate.No. 1 



§ A1KOPSIS. Gls. subequal, 2-ilowercd, with no rudiment, fls. both perfect. Dwarf. No. 2 



§ AVENA proper. Gls. equal, longer than the 2 lis., and strongly striate. Cultivated No. 8 



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

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

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

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

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



2 A. precox Beauv. Cajspitous ; culm erect, a few inches high ; lvs. \ — LI 

 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 

 lswer part of the back twice its length. — CD N. Y. to Virg. Jn. (Aira, L.) 



3 A. sativaL. CojbioxOat. Culm smooth, 2 — 4fhigh; lvs. linear-lanceolate, 

 veined, rough, with loose, striate sheaths; stip. lacerate; panicle loose; spikelets 

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

 ^.wned; paleai somewhat cartilaginous, closely embracing the caryopsis. — (I) A 



