GRAMINE^. (GRASS FAMILY.) 653 



39. TRISETUM, Persoou. (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 belou 

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

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



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

 Minutely soft-downy ; panicle dense, much contracted, 6\Ao\ig ov linear (2-3 

 long); glumes about the length of th: 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 capillar t/; spikelets 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-ehartaceous, 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- U-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 {V 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, JVIinn. (Nat. 

 from Eu.) 



* * Smaller flowered perennials. 



1. A. striata, Michx. (PI. 12, fig. 1,2.) C/airows and s?/ioo//i 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 ^-nerved ; rh chis smooth ; flowers short-bearded at base ; flowering glume 

 7-nerved, much longer than the ciliate-fringed 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, tlie lower 

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



