AvENA. CLXf. GRAMINE^. 609 



2. A. c;espitosa. (A. aristulata. Torr.") 



Caespitose, glabrous ; st. 18 — 30' high ; Ivs. narrow-linear, scabrous above, 

 smooth beneath, flat; _J9g?m<:;/c pyramidal, capillary, oblong, finally difiuse; aivns 

 straight, about as long as the paleoB which are longer than the bluish glumes. — 

 '2J. Swamps, Free States and Can. May. 



3. A. PUMiLA, Pursh. 



Sts. scarcely 1' high, erect, growing in tufts, scarcely longer than the 

 leaves ; Its. flat, smooth ; panicle small, fastigiate, few-flowered ; pedicels short ; 

 palece awnless, obtuse, twice the length of the glumes ; glumes with a mem- 

 branaceous margin, — 7|. 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. Mx. Aira pallens. Muhl.) 



St. erect, contracted at the nodes, slender, smooth, about 2f high ; Ivs. 

 lance-linear, about 3' long, roughish, on smooth, striate sheaths ; panicle oblong, 

 contracted, nodding, yellowish-green ; spikclels 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. — % Wet meadows, Mass., 

 N. Y. toFlor. May— July. 



2. T. puRPiRAscENs. Torr. (Avena striata. Michx. ?) 



St. leafy, 2f high ; Ivs. narrow-linear, keeled, 4 — 6' long, and with the 

 sheaths smooth ; panicle very simple, almost a raceme, few-flowered, 4 — 6' long ; 

 glumes 3-flowered, very unequal, entire; spikclels lanceolate, terete, often purple, 

 smooth ; loiccr palea 7-veined, 2-cleft at the extremity ; a?^vi geniculate. — % 

 Mountain bogs, N. Eng., N. Y., Can. June. 



3. T. suspiCATUM. Brown. (T. aroides. Palis. Aira. Linn.) 



St. a loot high ; lis. 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 ; palejX3 2, mostly hairy at base, the 

 lower one bifid, with a twisted or bent awn at the back. 



1. A. Ei.ATioR. (Arrhcnatherum. Palis.) 



.S/. 2—4 f high, geniculate, .smooth; Irs. lance-linear, rough on the margin 

 and upper surface; panicle loose, equal, nodding, branches in pairs or tcrnate ; 

 spikclels 2-flowered; awn twice as long as the palea; upper Jlou-er 5, mostly 

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

 May, June. 



2. A Pennsvlvanica. (Arrhcnatherum. Ttnr.) 



S^ erect, smooth ; lis. linear-lanceolale; /vf?r<c/e slender, Avith short, altei'- 

 nate branches ; au^n twice as long as the flowers, geniculate, from the base of 

 the lower palea; upper Jloircr awnless. — Fields and open woods, N. Eng. to 

 Car. and 111., rare. July. " ^ 



3. A. PRECOX. Pali.s. (Aira. Linn.) 



Caispito.se; si. erect, a few inches high ; Ivs. J — 1' long, rough ; sheaths Ciec\^\y 

 striate; panicle den.sc, racemose ; spikchls ovate, 2-flowcred, i,'^/«wr5 as long as 

 the flowers; Unnrr palea with a bent awn from the lower part of the back twice 

 its length.— OD N. Y. to Virg. Jn. 



4. A. SATlVA. Cammon Oat. — SI. smooth, 2 — 4f high; Ivs. linear-lanceo- 

 late, veined, rough, with loose, striate sheaths; slip, lacerate; punirle loose; 

 spikclels pedimculate, pendulous, 2-tlowcre(l, both flowers porfert, the lower one 

 mostly awned; palccr somewhat eartilnginous, (•lo-;elv fuil>rn<Miigthe caiyopsis. 



