AVENA. CLXI. GRAMINE. 609 
2. A. cmspiTésa. (A. aristulata. Torr. 
Czespitose, glabrous ; st. 18—30’ high; vs. narrow-linear, scabrous above, 
smooth beneath, flat; panicle pyramidal, capillary, oblong, finally diffuse; awns 
straight, about aslong as the palee which are longer than the bluish glumes.— 
2 Swamps, Free States andCan. May. 
3. A. PUMILA. Pursh. 
Sts. scarcely 1’ high, erect, growing in tufts, scarcely longer than the 
seaves ; dvs. flat, smooth ; panicle small, fastigiate, few-flowered ; pedicels short; 
pale@ awnless, obtuse, twice the length of the glumes; glumes with a mem- 
branaceous margin.—2 In barren, clayey soils, near brickyards, Penn. 
Pursh. Jn. = 
29. TRISETUM. 
Lat. tria, three, setum, a bristle ; a characteristic term. 
Spikelet 2—5-flowered ; glumes 2, as long as the flowers; lower 
palea with 2 bristles at the apex and a soft, flexuous awn from above 
the middle of the back; scales ovate ; fruit coated, furrowed. 
1. T. paLustre. Torr. (Avena. Mz. Aira pallens. Mul.) 
St. erect, contracted at the nodes, slender, smooth, about 2f high; Js. 
Jance-linear, about 3’ long, roughish, on smooth, striate sheaths ; panicle oblong, 
contracted, nodding, yellowish-green; spikelets 2—3 flowered, middle flower 
abortive, upper one pedicellate, its lower palea ending in 2 setose teeth, and 
awned below the tip, lower one mostly awnless——2 Wet meadows, Mass., 
N. Y. to Flor. May—July. 
2. 'T. pURPURASCENS. Torr. (Avena striata. Michx.? 
St. leafy, 2f high; lvs. narrow-linear, keeled, 4—6/ long, and with the 
sheaths smooth; panicle very simple, almosta raceme, few-flowered, 4—6’ long; 
glumes 3-flowered, very unequal, entire; spzkelets lanceolate, terete, often purple, 
smooth ; lower palea ‘7-veined, 2-cleft at the extremity; awn geniculate —2, 
Mountain bogs, N. Eng., N. Y., Can. June. 
3. T. suspicatum. Brown. (T.aroides. Palis. Aira. Linn.) 
St. a foot high; vs. narrow, 2—4’ long ; panicle contracted into a spike 2 
long; awn at length deflexed, longer than the glume.—?| Rocks and moun- 
tains, Little Falls, N.Y. Gray. White Mts.,N.H. Pickering. Jn. 
30. AVENA. 
Spikelets 2—5-flowered; glumes 2, loose and membranaceous, 
subequal, longer than the flowers; paleze 2, mostly hairy at base, the 
lower one bifid, with a twisted or bent awn at the back. 
1. A. ELATIOR. (Arrhenatherum. Palis.) 
St. 2—4f high, geniculate, smooth; /vs. lance-linear, rough on the margin 
and upper surface; panicle loose, equal, nodding, branches in pairs or ternate ; 
spikelets 2-flowered; awn twice as long as the palea; wpper flower $, mostly 
awnless.—A tall grass, introduced and naturalized in cultivated grounds. 
May, June. 
2. A PennsytvaNnica. (Arrhenatherum. Torr.) 
St. erect, smooth ; dvs. linear-lanceolale; panicle slender, with short, alter- 
nate branches; awn twice as long as the flowers, geniculate, from the base of 
the lower palea; upper flower awnless.—@) Fields and open woods, N. Eng. to 
Car. and Ill., rare. July. ss 
3. A. pRecox. Palis. (Aira. Linn.) 
Ceespitose; st. erect, a few inches high ; dvs. 3—1’ long, rough; sheaths deeply 
striate; panicle dense, racemose; 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. 
4. A. sativa. Common Oat.—St. smooth, 2—4f high; Jvs. linear-lanceo- 
late, veined, rough, with loose, striate sheaths; stip. lacerate; panicle loose; 
spikelets pedunculate, pendulous, 2-flowered, both flowers perfect, the lower one 
mostly awned ; pale@ somewhat cartilaginous, closely embracing the caryopsis. 
