AJIRHENATHERUM. TRIANDRIA. DIGYNIA. 131 



SETUM pennsylvanicum P, de B c auv. Roem, i^Sckult, 

 II. p. 658. 



Cw/m erect, smooth. XeaT;es linear-lanceolate. Branches of the 

 fianicle short, alternate ; fiedicels scabrous. Calyx unequal, 

 white, shorter than the florets. Florets bearded at the base, 

 one of them awnless, the ether with a geniculate awn at the 

 base of the inferior valve. Mu h I. 



Hab. In Pennsylvania. Muhlenberg. In fields and open 

 woods. New-England to Carolina ; frequent. July. Pursh. 

 What I formerly considered as the Avena /lennsylvanica of 

 Linn a u s is my Trisetum fiurfiurascrns. This species I 

 have never seen. By AI u /i ie n b erg's description it so 

 strongly resembles tlie preceding, that I am unable to point 

 out atiy very distinguishing characters. There can be no doubt 

 that it belongs to the genus Arrhenatherum. though 

 Be auv ois has referred it to TRisETum, where P era o on 

 long since conjectured it to belong.f 



39. AVENA. L. 



Calyx membranaceous, many - flowered, generally 

 longer than the florets. Corolla generally bearded at 

 the base ; inferior valve bilaciniate, with a twisted awn 

 on the back. Seed coated. Gen. pi. 122. A'utt, 

 Gen, I. p. 74. Roe in. ^ Schult. Gen. 238. P. de 

 Beauv. t. XVIII. f. 5, Trin, AgrosU 116. Panicle 

 spreading or racemose. Oat-grass, 



A. prcecox P. de B.: panicle in a dense raceme ; florets 

 as long as the calyx ; awn exserted ; leaves setaceous, Roem, 

 4/- Schult, II. p. G67. Avena jsrarox L. W it I d. Spec, 

 I. p. 380. Smith FL Brit. I. p. 87. Eng. Bot. t. 1296. 

 Pursh Ft. I. p. 77. Muhl. Gram, p. 86. 



Root annual. Culm 3 — 4 inches high, cespitose, erect. Leaves 

 half an inch or more in length, scabrous. Sheaths many-angled, 

 smooth. Sti/iule oblong, obtuse, clasping. Panicle obiung, 

 about an inch long ; branches in pairs, appressed. Sfiikeleta 

 ovate, 2-flowered, Calyx rather longer than the florets; 

 glumes nearly equal, lanceolate, acute, smooth, except on the 

 upper part of the keel. Inferior valve of the corolla lanceolate ; 

 apex scabrous, attenuated and bifid; awn inserted into the 



f I have another species of AnnaENATHEnuM sent to me from Kentucky 

 by Prof. Rafinesqxie, which agrees pretty well with the description of 

 Muhlenberg's Avena pennsylvanica, except that the branches of the 

 panicle are not alternate, but fa.-.cicied, and the upper floret has the supe- 

 rior valve furnished with a short awn a little below the tip. I call it 

 A. ke7iucckensis. It may possibly be the A. americana of -P. de Beaxiv., of 

 which species the author has given no description. 



