AVENA. CLXI. GRAMINE./E. 609 



2. A. OESPITOSA. (A. aristulata. Torr.) 



-Caespitose, 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 paleae which are longer than the bluish glumes. 

 % Swamps, Free States and Can. May. 



-3. A. PUMILA. Pursh. 



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

 leaves ; Ivs. flat, smooth ; panicle small, i'astigiate, few-flowered ; pedicels short ; 

 palea 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. trio,, 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 ; 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. 1L Wet meadows, Mass., 

 N. Y. to Flor. May July. 



2. T. PURPURASCENS. 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; spikclets lanceolate, terete, often purple, 

 smooth ; lower palea 7-veined, 2-cleft at the extremity ; awn geniculate. 1\. 

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



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



St. a foot high ; Ivs. 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. 



S pikelets 2 5-flowered ; glumes 2, loose and membranaceous. 

 subequal, longer than the flowers ; paleae 2, mostly hairy at base, the 

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



1. A. ELATIOR. (Arrhenatherum. Palis.) 



S f . 2 4f high, geniculate, smooth ; Ivs. 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 ; upper flower Q , mostly 

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

 May, June. 



2. A PENNSYLVANIA. (Arrhenatherum. Torr.) 



SI. erect, smooth ; Ivs. 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. (T) Fields and open woods, N. Eng. to 

 Car. and 111., rare. July. 



3. A. PR.ECOX. Palis. (Aira. Linn.) 



Csespitose ; st. erect, a few inches high ; Ivs. 1' long, rough ; sheaths deeply 

 striate ; panicle dense, racemose ; spikclets 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. Cvflimon Oat. St. smooth, 2 4f high ; Ivs. linear-lanceo- 

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

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

 mostly awned; pal& somewhat cartilaginous, closely embracing: the caryopsis. 



