GRAMINE^E. (GRASS FAMILY.) 653 



39. TRISETUM, Persoon. (PI. 12.) 



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

 glume compressed-keeled, of about the same thin-membranaceous texture as 

 the empty glumes, bearing a bent or flexuous (rarely twisted) awn at or below 

 the sharply 2-toothed or 2-pointed apex (whence the name, from tris, three, 

 and seta, a bristle) ; otherwise nearly as in Avena. Ours are perennials. 



1. T. SUbspicatum, Beauv., var. molle, Gray. (PI. 12, fig. 1, 2.) 

 Minutely soft-downy ; panicle dense, much contracted, oblong or linear (2-3' 

 long) ; glumes about the length of the 2-3 smooth flowers ; awn dorsal, di- 

 verging, much exserted. Mountains and rocky river-banks, N. New Eng. to 

 L. Superior, and northward. July. About 1 high; leaves flat, short. (Eu.) 



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

 loose, the branches capillary; spilcelets flat (3" long); lower glumes shorter 

 than the two smooth lanceolate flowers ; the upper flower on a slightly hairy 

 joint of the rhachis, with a slender spreading or bent awn next the short 2- 

 pointed tip, the lower commonly awnless or only mucronate-pointed. Low 

 grounds, southern N. Y. to 111., and southward. June. Culm slender, 2-3 

 high ; leaves flat, short ; spikelets yellowish-white, tinged with green. 



40. AVENA, Tourn. OAT. (PI. 12.) 



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

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

 glumes ; the uppermost flower imperfect ; rhachis and base of the flower often 

 bearded. Flowering glume rounded on the back, mostly 5-11-nerved, bear- 

 ing a long usually bent or twisted awn on the back or between the two acute 

 teeth at the apex, proceeding from the mid-nerve only. Stamens 3. Grain 

 oblong-linear, grooved on one side, usually hairy at least at the top, free, but 

 invested by the palet. (The classical Latin name.) 



* Spikelets large (!' long) ; annual. 



A. FATUA, L. Resembling the common oat (A. sativa), the few spikelets 

 in a loose panicle, mostly pendulous; flowering glumes covered with long 

 brownish hairs and bearing a bent awn 1-2' long. Wise., Minn. (Nat. 

 from Eu.) 



* # Smaller-flowered perennials. 



1. A. Striata, Michx. (PI. 12, fig. 1, 2.) Glabrous and smooth, through- 

 out, slender (1-2 high) ; leaves narrow; ligule short, truncate ; panicle sim- 

 ple, loose; spikelets (6" long) on capillary pedicels, 3 - 6-flowered, much 

 exceeding the scarious-margined purple acute empty glumes ; lower glume 1-, 

 upper 3-nerved ; rhachis smooth ; flowers short-bearded at base; flowering glume 

 7-nerved, much longer than the ciliate-f ringed palet (4" long), mostly shorter 

 than its soon bent or divergent awn, which rises just below the tapering very 

 sharply cuspidate 2-cleft tip. Rocky, shaded hills, N. New Eng., N. Y., and 

 northwestward. June. 



2. A. Smithii, Porter. Taller (2|-4| high), rather stout; leaves broadly 

 linear (3 - 6" wide) and taper-pointed, flat, and with the sheaths and culm re- 

 trorsely scabrous; ligule elongated, acute; panicle larger (6-12' long), the 

 few branches at length spreading; empty glumes slightly purplish, the lower 

 3-nerved, the upper 5-nerved, scabrous on the nerves ; rhachis minutely hispid , 



