Trisetum. GRAMINB.E. 295 



nerved. Florets herbaceo-cliartaceous, becoming tinner than the ghiraes, upon a 

 hairy-bearded rhachis. Lower palet rounded on the back, 5-1 l-nerved, acutely 

 2-cleft at tip, bearing from between the teeth a long bent or twisted awn which pro- 

 ceeds from the midnerve only. Upper palet equalling the lower, minutely bihd. 

 Stamens 3. Scales 2, bifid at apex. Ovary hairy above : styles short, distant ; 

 stigmas densely plumose. Grain cylindrical-oblong, deep-grooved, hairy throughout 

 or at the tip only, closely invested by the upper palet. 



A genus of about 30 annual and perennial species, belonging to temperate and cold regions. 

 Two species are found in the Eastern States. Trisetum and Airhcnatherum are by some botanists 

 included as sections of this genus. 



1. A. fatua, Linn. An erect annual, 2 or 3 feet high, smooth except at tlie 

 hairy nodes, with fiat slightly scabrous leaves and loose sheaths: panicle 8 to 10 

 inches long, the few-fiowered rays spreading equally ; spikelets about an inch long, 

 the scarious pointed glumes longer than the florets, often purplish at base : lower 

 palet about 6 lines long, firm at base, scabrous and covered with long brown hairs, 

 its lobes tapering to a sharp point ; awn about twice the length of palet, bent near 

 the middle and twisted below: grain very hairy. — Kunth, Enum. i. 302, and 

 Suppl. 256; Benth. Illust. Brit. Flor. t. 1179; Watson, Bot. King. Exped. 392. 



Common in fields. Probably a native of the Mediterranean region, but naturalized in many 

 grain -growing countries, including South America and Australia. As the " Wild Oat " it is 

 highly valued for hay. It is supposed to be the original of the cultivated oat {A. saf.iva), which 

 is said to readily degenerate into this. Professor Buckman of England gives a detailed account 

 of having produced from the seeds of this a good variety of smooth cultivated oat in a few years' 

 successive sowing and selection. 



34. TRISETUM, Beauv. 



Panicle mostly narrow, loose or dense and even spike-like. Spikelets 2- (rarely 



3- or more-) flowered. Glumes unequal, acute, keeled, membranaceous with scarious 



margins, the lower l-nerved, upper (sometimes both) 3-nerved. Florets more or less 



separated by the hairy joints of the rhachis, the last one of which extends beyond 



the upper spikelet as a rudiment, sometimes bearing an imperfect floret. Palets 



similar in texture to the glumes, the lower keeled, 5-nerved, acute, more or less 



deeply bifid, bearing above the middle an aviai which proceeds from the midnerve, 



usually twisted at the base and bent near the middle. Upper palet 2-nerved and 



2- toothed. Ovary hairy or smooth : styles stigmatic from near the base. Grain 



smooth, not furrowed. 



Over 60 species have been described, having a geographical range similar to Avena, to which 

 some authors unite it. Two species belong to the Atlantic States. 



* Panicle open ivlth elongated rays : ova.ry hairy at the apex. 



1. T. cernuum, Trin. Culm 2 or 3 feet high, with flat leaves about 6 inches 

 long and nearly half an inch wide : panicle 6 to 10 inches long, very open, nodding 

 above ; rays in distant clusters, cernuous, capillary, roughened, flower-bearing above 

 the middle ; spikelets 2-3- (rarely 4-) flowered : lower floret Avith a short-bearded 

 callus, the others spreading, distant, upon hairy joints half as long as tlie florets : 

 glumes very unequal, the lower narrow, subulate, less than one-half the length of the 

 broad 3-nerved obtuse and mucronate upper one : lower palet about 3 lines long, 

 slightly scabrous especially above, bearing a slender awn twice its own length, and 

 terminating in two subulate teeth, which bear set;i3 nearly a line long ; uppermost 

 joint of the rhachis with a long weak awn. — Mem. Acad. St. Petersb. 1831, 61 ; 

 Hook. Fl. Bor.-Am. ii. 244. Avena cernua, Kunth, Enum. i. 306; Griseb. in Ledeb. 

 Fl. Eoss. iv. 419. 



