572 GRAMINE^E. (GRASS FAMILY.) 



2. VAHL6DEA, Fries. Glumes mare boat-shaped, longer than the flower* : 

 lower palea of a firm or coriaceous texture, nerveless, the truncate-obtuse tip mostly 

 entire; the awn borne at or alwve the middle : grain grooved, flattish, free. 

 3. A. atropurpiirea, Wahl. Culms 8'- 15' high, weak; leaves flat or 



rather wide ; panicle of few spreading branches ; awn stout, twice the length of 



the paleae. ty Alpine tops of , the White Mountains, and those of N. New 



York. August. (Eu.) 



48. DANTH01VIA, DC. WILD OAT-GRASS. 



Lower palea (oblong or ovate, rounded-cylindraceous, 7-9-nerved) bearing 

 between the sharp-pointed or awn-like teeth of the tip an awn composed of the 

 3 middle nerves, which is flattish and spirally twisting at the base : otherwise 

 nearly as in Avena. Glumes longer than the imbricated flowers. (Named for 

 Danthoine, a French botanist.) 



1. I>. spicata, Beauv. Culms tufted (l-2high); leaves short, nar- 

 row and soon involute ; sheaths bearded at the throat ; panicle simple, raceme- 

 like (2' long); the few spikelets appressed, 7-flowered; lower palea broadly 

 ovate, loosely hairy on the back, much longer than its lance-awl-shaped teeth. 

 1J. Dry and sterile or rocky soil. July. 



49. TRISETUM, Persoon. TRISETUM. 



Spikelets 2 - several-flowered, often in a contracted panicle ; the lower palea 

 compressed-keeled, of about the same membranaceous texture as the glumes, 

 bearing a bent or flexuous (rarely twisted) awn below the sharply 2-toothed or 

 2-pointcd apex (whence the name, from tris, three, and seta, a bristle) : other- 

 wise nearly as in Avena. 



1. T. SUbspicatum, Beauv., var. inollc. Minutely soft-downy ; pani- 

 cle dense, much contracted, oblong or linear (2' -3' long) ; glumes about the length 

 of the 2-3 smooth flowers ; awn diverging, much exserted. (Avena mollis, 

 Michx.) }\. Mountains and rocky river-banks, N. New England to Wisconsin, 

 and northward; rare. July. About 1 high: leaves flat, short. (Eu.) 



2. T. palustre, Torr. Smooth; panicle rather long and narrow (5' long), 

 loose, the branches capillary; spikelets fiat (3" long) ; glumes shorter than the 2 

 smooth lanceolate flowers, of which the upper is on a slightly naked joint of the 

 rhachis, and bears a slender spreading or bent awn next the short 2-pointed tip, 

 while the lower one is commonly awnless or only mucronate-pointed. 1J. (Arena 

 palustris, Michx. Aira pallens, MuhL) Low grounds, S. New York to Illinois, 

 and southward. June. Culm slender, 2 -3 high : leaves flat, short. Spike- 

 lets yellowish-white, tinged with green. 



5O. AVENA, L. OAT. 



Spikelets 2 - many-flowered, panicled; the flowers herbaceo-chartaceous, or 

 becoming harder, of firmer texture than the large and mostly unequal glumes ; 

 the uppermost imperfect. Lower palea rounded on the back, mostly 5-11- 

 nerved, bearing a long usually bent or twisted awn on the back or below the 



