GRAMINE^l. 403 



sometimes eroded, with a twisted awn on the back. Scales 

 ovate. Seed coated, furrowed. Panicle compound, loose. 



Triandria. Digynia^ 



1 . A. pr&cox P. de B. : panicle in a dense raceme ; florets as long 

 as the glumes ; awn exserted ; leaves setaceous. Air a prtecox Linn, 



HAB. Sandy fields. N. J. to Vir. June. 0. Culm 3 4 feet 

 high, cespitose. Panicle oblong. 



2. A. elatior Linn. : panicle equal, nodding ; awn as long again as- 

 the floret; culm geniculate, smooth; root nodose. rfrrhenatherum 

 avenaceum P. de . Torr. 



HAB. Fields. N. S. ; rare. June. U> Culm 3 feet high. Pan- 

 icle loose, with the branches in pairs or ternate. 



27. TRISETUM. Pers. 



Lower fyalea with 2 bristles and a tender flexuous beard 

 above the middle of its back. Scale lanceolate. (Other char- 

 acters of Avena.) Triandria. Digynia. 



1. T. pennsylvanicum P. de B. : panicle attenuated; awn twice as 

 long as the florets ; seed villous. Arena pennsylvanica Linn. Arrht- 

 natherum pennsylvanicum Torr. 



HAB. Fields. N. Eng. to Car. July. 0, Culm erect, smooth. 

 Panicle with short branches. 



2. T. palustre Torr. : panicle contracted, nodding, somewhat verti- 

 cillate; glumes 2 3-flowered ; florets smooth, acuminate.; lower one 

 awnless ; lower palea of the upper floret bicuspidate, awned below the 

 tip. Avena palustris Mich. Air a pattens Muhl. 



HAB. Wet meadows. N. Y. to Flor. May- July. 2{. Culr* 

 12 feet high. Panicle with the lower branches in fives. 



3. T. purpurascens Torr. : panicle very simple, somewhat racemose, 

 few-flowered ; glumes 3-flowered, very unequal, entire ; culm and 

 leaves smooth ; stipule very short, truncate. Avena striata Mich. ? 



HAB. Mountain meadows. Can. and N. S. 1. Culm 



2 feet high, leafy. Leaves narrow-linear. Panicle 4 6 inches 

 long. Glumes purplish, smooth. 



4. T. subspicatum Brown : panicle subspiked ; awn at length deflex- 

 ed, exceeding the glume. T. aroides P. de B. Torr. Aira subspicattt 

 Linn. 



HAB. Rocks and mountains. Little Falls, N. Y. Gray. White 

 Mountains, N. H. Rocky Mountains. Arc. Amer. June. If. 

 Culm a foot high. Leaves narrow, 2 4 inches long. Panicle 

 2 inches long, somewhat spiked. First noticed as an American 

 plant by Dr. Torrey, in Ann. N. Y. Lye. i. 154. The specimens 

 which I have received from Dr. Gray, agree exactly with those 

 from the White Mountains, collected by Dr. Pickering, but they 

 are nearly three times the size of my specimen of A. subspicata, 

 from Switzerland ; the panicle also is more loose and the glumes 

 of a lighter colour. 



