AUISTIDA. 



CLXI. GRAMlNEiE. 



8 8 



595 



Tribe 1. STIPACEJE.— Infloresence panicled. Spikelets solitary, l-flcnvcr- 

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

 involute, awned. 



1. ARISTlDA. 



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



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

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

 or obsolete. 



1. A. DicHOTOMA. Michx. Povcrfy Grass. 



Coespitose ; st. dichotomously branching; panich 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, filiform, 2 — 3f high ; Ivs. very narrow, flat, erect, a foot 

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

 short, clavate, appressed pedicels; aic7is nearly equal, divaricate, twice the 

 length of the paleae; palece often dark purple.— '2]. 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 awns short, erect, intermediate one longer, spreading. —% Masa. 

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



4. A. TUBERCULOSA. Nutt. L,ong-av:ned Poverty Grass. 



St. erect (declinate at base), 8—20' high, rigid, with small tubercles in the 

 axils of the numerous branches ; 7wdes tumid ; Ivs. long and narrow-linear ; 

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

 awned ; upper palece involute, the awns 2' long, hispid upwards, twisted together 

 to near the middle, thence finally horizontally divaricate.— 'Zj. A very singular 

 species, in dry prairies. III, Mead I July, Aug. 



