24. HIEROCH'LOA, Gmel. Seneca Grass. (Gr. sacred, glass; from its fragrance.) Spikelets 3-flowered; glumes 2, scarious; lateral flowers staminate, triandrous; central flower , dian-drous (rarely triandrous). - Sweet-scented. Inflor. paniculate.
1 H. borealis R. & Sch. Smooth, glossy; culm simple, erect, 15 - 20'; radical lvs. as long as the stem, cauline 2 - 4' long, lanceolate, mucronate; panicle rather 1-sided and spreading, pyramidal, few-flowered, 2 - 3' long; branchlets flexuous; spikelets broad, subcordate, colored, unarmed; glumes acuminate; lower pale ciliate. - Wet meadows, Virg. to Arc. Am. Very fragrant. May.
2 H. alpina R. & S. Smooth; culm erect, stout, 6 - 8'; lvs. linear-lanceolate, acute; sheaths tumid, longer than the internodes; panicle ovoid, 1 /2 - 2' long, with the branches in pairs; spikelets purple, compressed, large, longer than the branches; glumes lanceolate; lower fl. with an awn about as long as the pales. - Summits of the White Mts. (Bigelow). Jn.
25. HOL'CUS, L. Soft Grass. (Gr. something which draws; application obscure.) Spikelets 2-flowered; glumes herbaceous, boat-shaped, mucronate; flowers pedicellate, the lower one perfect and awnless, upper one or neuter, awned on the back. - Fls. in an open panicle.
H. lanatus L. Hoary pubescent; culm 1 1/2 - 2f high; lvs. lance-linear, 2 - 5' long; sheaths striate; pan. oblong, dense, whitish, with a purple tinge; fls. shorter than the glumes; sterile one with a recurved, included awn. - Common in wet meadows, N. Eng., to the uplands of Ga. A beautiful grass, very soft with - whitish down. Jl.
26. AI'RA, L. (Gr. 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.................................
§ Glumes about as long as the pales. Awns long or short.......................................................................
Nos. 2, 3
1 A. atropurpurea Wahl. Caespitous, a foot high; culms very slender; lva. 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, trichotomous, with long, flexuous branches; awns geniculate, twice longer than the pales. - Vales and hills, U. S. and Brit. Am., common. An erect, elegant grass, growing in tufts. Jn.
3 A. caespitosa L. Csespitous, glabrous; st. 18 - 30' high; lvs. narrow-linear, scabrous above, smooth beneath, flat; panicle pyramidal, capillary, oblong, finally diffuse; axons straight, about as long as the pales, which are longer than the bluish glumes. - Swamps, N. States and Can. May. (A aristulata Torr.)
. 27. DANTHO'NIA, DC. (In honor of M. Danthoine, a French botanist.) Spikelets 2 - 7-fiowered; glumes 2, subequal, longer than the spikelet of flowers, cuspidate; paleae 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, lower 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 1-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'NA, L. Oat. Spikelet 2 to 5-flowered; glumes 2, loose and membranous, awnless, often as long as the pales; pales 2, herbaceous, at length subcoriaceous, the lower one bifid and usually with a twisted or bent awn at the back. - Fls. paniculate.
§ ARRHENATHERUM. Gls. unequal, 2-flowered, with a rudiment; lower fl. staminate
§ AIROPS1S. Gls. subequal, 2-flowered, with no rudiment, fls. both perfect. Dwarf.........
§ AVENA proper. Gls. equal, longer than the 2 fls., and strongly striate. Cultivated.........
1 A. elatior L. Culm 2 - If, 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. praecox Beauv. Caespitous; culm erect, a few inches high; lvs. 1/2 - 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. - N. Y. to Virg. Jn. (Aira, L.)
3 A. sativa L. COMMON OAT. Culm smooth, 2 - 4f high; lvs. linear-lanceolate, veined, rough, with loose, striate sheaths; slip, lacerate; panicle loose; spikelets pedunculate, pendulous, 2-flowered, both flowers perfect, the lower one mostly awned; paleae somewhat cartilaginous, closely embracing the caryopsis. - A highly important grain, one of the staple productions of the soil; said to have been first discovered in the Island of Juan Fernandez.
β . Nigra. Black Oats. Paleae dark brown, almost black, awnless.