VENA. CLXI. GRAMINELE. 609 



2. A. c;ESPiT6sA. (A. aristulata. Torr.) 



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

 smooth beneath, flat ; panicle pyramidal, capillary, oblong, finally diffuse ; awns, 

 traight, about as long as the palese 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 

 eaves ; Ivs. flat, smooth ; panicle small, fastigiate, few-flowered j 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. 



Lut. (ria, 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. Me. 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. 7L Wet meadows, Mass.. 

 N.Y.toFlor. May July. 



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



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

 sheaths smooth ; panicle very simple, almost a raceme, few-flowered, 4 & long ; 

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

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

 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 

 ong ; awn at length deflexed, longer than the glume. % Rocks and moun- 

 dins, Little Falls, N. Y. Gray. White Mts.j N. H. Pickering. Jn. 



30. AVENA. 



Spikelets 2 5-flowered ; glumes 2, loose and membranaceous, 

 nubequal, 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. (Arfhenatherum. Palis.) 



Sf. 2 4f high, geniculate, smooth ; Ivs. lance-linear, rough on the margin 

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

 ".pikelets 2-flowered ; awn twice as long as the palea ; upper flower $ , most \y 

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

 May, June. 



2. A PENNSYLVANIA. (Arrhenatherum. Torr.) 



St. 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. Fields and open woods, N. Eng. to 

 Car. and 111., rare. July. 



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



Caespitose ; st. erect, a few inches high ; Ivs. 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; Ivs. linear-lanceo- 

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

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

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



