662 GR AMINES. 



MITHLENBERGIA, Schreber. 



M. arenicola, Buckley. Culms tufted, simple (2 high) ; leaves short, 

 flat, narrow-linear ; panicle terminal, long-peduncled, simple, spreading ; 

 palese 3-nerved, bearded at the base, four times as long as the oval obtuse or 

 acute glumes, and equalling the rough avvn. (M. caespitosa, Chapm.) Dry 

 pine barrens, Florida, and westward. 



M. sylvatica, T. & Gr. Culms diffuse, branched (2 -3 high) ; pani- 

 cles contracted ; paleae as long as the nearly equal short-awned glumes, the 

 lower one with its awn 2-3 times the length of the spikelet. North Caro- 

 lina, Tennessee, and northward. 



CALAMAGROSTIS, Adans. 



C. brevipilis, Gray. Culms tufted, simple. (2-3 high) ; leaves linear, 

 setaceously attenuate ; panicle long, narrow ; glumes ovate-lanceolate, the 

 upper one barely shorter than the paleaa, the lower one half as long ; palese 

 bearded on the back, twice as long as the hairs at their base, awnless ; rudi- 

 ment of a second flower none. East Florida, and northward. 



THURBERIA, Benth. 



Low tufted annual grasses, with erect branching culms, soft-hairy Waves, 

 and 2-flowered spikelets in an erect narrow terminal panicle. Glumes 2, 

 unequal, 3-nerved, hispid. Paleae 2, included, the lower one smooth, coria- 

 ceous, armed below the apex with a stout bent dorsal awn ; the upper one 

 thin, with an awn-like pedicel at its base. Stamens 2. Grain free. 



T. Arkansana, Benth. Culms 6' - 12' high. Leaves shorter than the 

 culm ; panicle 2' - 3' long. On a shell mound near Apalachicola. April. 



ARISTIDA, L. 



A. simpliciflora, Chapm. Culms filiform (2 high), forking ; leaves 

 flat, smoothish; racemes simple, straight (6' -9' long), loosely flowered; 

 glumes nearly equal, awn-pointed, the lower one rough on the keel, longer 

 than the paleae ; middle awn circular-curved near the base. Damp pine 

 barrens, West Florida. 



A. gyrans, Chapm. Culms simple (1 high), purple; leaves convolute- 

 filiform ; panicle simple, with the branches appressed ; lower glume truncate, 

 short-awned, as long as the paleae, the upper one a third longer, attenuate ; 

 paleae long-stipitate, the awns nearly equal, curved. Keys of Caximbas 

 Bay, South Florida. 



A. COndensata, Chapm. Culms stout, simple (2 high) ; leaves rigid, 

 flat or concave, soon convolute; panicle (1-1 long), long-peduncled, con- 

 tracted, densely many-flowered ; glumes equal, awn-pointed, longer than the 

 paleae; awns straight, longer than the glumes. Dry sandy pine barrens, 

 West Florida. 



