452 



GRAMINEiE. 



Trisetum. 



28. TRISETUM. Pers. ; Kunth, enam. 1. p. 295. TRISETUM. 



[So named from the Latin, in allusion to the three bristles of the flowers.] 



Spikelets 2 - 4-flowered. Glumes membranaceous, keeled, awnless. Pales herbaceous : 

 lower one with 2 long cusps at the summit, and a twisted awn on the back ; upper one 

 bicarinate. Caryopsis smooth, without a longitudinal groove. — Mostly alpine or sub-alpine 

 grasses. Leaves flat. Panicle contracted, rarely diffuse. 



1. Trisetum molle, Kunth. (Plate CLIV.) Soft Trisetum. 



Whole plant minutely and softly pubescent ; panicle contracted and somewhat spiked ; 

 glumes 2-flowered, the flowers not bearded ; awn about the length of the palea, not twisted, 

 diverging or recurved. — Kunth, "gram. 1. p. 101," and enum. 1. p. 298 ; Trin. act. Petrop. 

 (1830), 1. p. 64. T. subspicatum, Bed, hot. p. 403. Avena mollis, Michx. fl. 1. p. 72. 



Perennial. Culm 12-15 inches high, mostly cespitose, erect, slender ; the pubescence 

 mostly retrorse. Leaves narrowly linear, 1-2 inches long, hairy at the base. Panicle 

 2-3 inches long ; the branches appressed, and rather densely flowered. Glumes a little 

 unequal, lanceolate, acute, rough on the keel. Lower palea with 2 long sharp cusps at the 

 summit ; the awn arising between the cusps, and about the length of the entire palea. 



Rocky banks of rivers, and on mountains ; northern and western parts of the State. Fl. 

 July. Very nearly allied to T. subspicatum, and regarded by Beck and Hooker as identical 

 with that species. 



29. AVENA. Linn. ; Kunth, enum. 1. p. 299. oat. 



[A name of doubtful origin.] 



Spikelets 3 - many-flowered ; the flowers rather remote, the uppermost imperfect. Glumes 

 thin and membranaceous. Palea? herbaceous ; the lower one with a twisted awn above 

 the base, mostly bifid at the summit. Caryopsis with a longitudinal groove on one side, 

 hairy at the summit. 



1. Avena Pennsylvanica, Linn. Pennsylvania Wild-oat. 



Panicle attenuated, loose, nodding, the branches somewhat verticillate ; spikelets 2-3- 

 flowered ; the flowers smooth (lowest one often awnless), upper one on a hairy pedicel ; 

 lower palea with a slender awn below the bifid tip, about twice the length of the flower. — 

 Linn. sp. 1. p. 79; Willd. sp. 1. p. 445; Kunth, enum. 1. p. 303. A. palustris, Michx. 

 fl. 1. p. 72 ; Pursh, fl. 1. p. 86 ; Muhl. gram. p. 186 ; Kunth, I. c. ; Darlingt. fl. Cest. p. 

 67. Trisetum Pennsylvanicum, Beauv. agrost. p. 154. Trisetum palustris, Torr. fl. 1. 

 p. 126 ; Trin. act. Petrop. (1830), 1. p. 67 ; Beck, hot. p. 403. Aira pallens, Muhl. I. c. ; 

 Ell. sk. 1. p. 151. 



