Aristida. 



CLXI. GRAMINE^. 



595 



Tribe 1. STIPACEJE.— Infloresence panicled. Spikelets solitary, 1-flower- 

 ed. Glumes membranaceous. Paleaa mostly two, lower one coriaceous, 

 involute, awned. 



1. ARISTlDA. 



Lat. arista, an awn ; characteristic of the genus. 



Panicle contracted or racemose ; glumes 2, unequal ; paleas pedi- 

 cellate, lower one with 3 long awns at the tip, upper one very minute 

 or obsolete. 



1. A. DiciiOTOMA. Michx. Poverty Grass. 



Csespitose; 5^. dichotomously branching; panicle contracted-racemose; 

 lateral awns very short, the intermediate one nearly as long as the paleae, con- 

 torted.— A slender grass, in sandy soils, U. S., common. Stems 8—12' high, 

 branching at each joint. Leaves very narrow, with very short, open sheaths, 

 and a very short stipule. Spikelets slender, on clavate peduncles, Aug. 



2. A. PURPURASCENS. Poir. 



St. erect, simple, filiCorm, 2— 3f high ; Ivs. very narrow, flat, erect, a foot 

 in length, with short, open sheaths; fanicle long, loosely spicate ; spikelets on 

 short, clavate, appressed pedicels; awns nearly equal, divaricate, twice ihe 

 length of the palece; pakce often dark purple.— I]. Sandy woods, Northern 

 States. Sept. 



3. A. GRACILIS. Ell. 



St. very slender, a foot or more high ; Ivs. setaceous, erect, with short 

 sheaths, pilose at the throat ; panicle very slender ; spikelets somewhat remote, ap- 

 pressed; lateral aiais short, erect, intermediate one longer, spreading. —% Mas.**. 

 and S. States. A grass of little value, as well as the other species ot this genus. 



4. A. TLBERCULosA. Nutt. Loni^-ainird Pavcrty Grass. 



St. erect (declinatc at ba.se), 8—20' high, rigid, with small tubercles in the 

 axils of the numerous branches; mxhs tumid; Irs. long and narrow-linear; 

 panicle large, loose, simple; spikelets pedicellate; glumes nearly 1' long, linear, 

 awned ; vpper pa/rct involute, the awns 2' long, hispid upwards, twisted together 

 to near the middle, thence finally horizontally divaricate.— 94- A very smgular 

 species, in dry prairies, III., Mta.fl ! July, Aug. 



