64 Bulletin VII. 1. 



six to ten lines long, usually rather strongly three- to five-nerved, 

 exceeding the flowering glume; flowering glume three-awned, 

 awns very unequal, the lateral ones straight, one to three lines 

 long, (sometimes wanting, variety uniaristata)^ the middle one an 

 inch long and soon abruptly recurved. Dry soil in open ground. 

 Humboldt, West Tennessee, September (A. Gattinger). 



2. Aristida dichotoma Michx. Poverty-grass. 



Plate XIX. Figure 73. 



A low, much-branched annual six to twenty-four inches high, 

 with few-flowered, spike-like, simple panicles one to four inches 

 long. Sheaths smooth or somewhat scabrous; ligule a minute 

 fringe of hairs; leaf-blade very narrow involute, one to six inches 

 long. Spikelets erect, three to four lines long; empty glumes nearly 

 equal, linear, the upper often mucronate-pointed, equalling or more 

 often exceeding the flowering glume; flowering glume with minute 

 appressed hairs on the back, three-awned, the lateral awns very 

 short and erect, the middle one soon reflexed and flexuose at the 

 base. Callus hairy. 



A worthless grass, common in dry, sandy or gravelly fields, etc- 

 September — October. 



3. Aristida gracilis Ell. Slender Triple-awn. 



Plate XIX. Figure 74. 



A slender, erect grass twelve to twenty-four inches high, branched 

 near the base, the culm and branches terminating in slender, 

 rather densely-flowered racemose or spike-like panicles, three to 

 seven inches long. Rays of the panicle in pairs, erect, one- to sev- 

 eral-flowered. Sheaths smooth or pilose near the base; ligule a 

 minute fringe of short hairs; leaf-blade three to five inches long, 

 about a line wide, soon convolute. Spikelets two to three lines 

 long (exclusive of the awns); empty glumes one-nerved, narrowly 

 lanceolate, nearly equal, or the lower one a little shorter than the 

 upper, which is usually short-awned or mucronate-pointed; flower- 

 ing glume usually a little longer than the empty ones, rough and 

 usually spotted on the back, three-awned, the lateral awns straight 

 and one-third to one-half the length of the divaricate or reflexed 

 middle one. Callus hairy. In sandy, gravelly or poor soils; appar- 

 ently less common than A. dichotoma. September — October. 



4. Aristida purpurascens Poir. Beard-grass or Purple Triple Awn. 



Plate XIX. Figure 75. 



A sparingly-branched perennial one and one-half to three feet 

 high, with narrow many-flowered panicles six to fifteen inches long. 

 Sheaths smooth or sometimes pilose, the lower ones imbricated; 

 ligule minute; leaf-blade one to two lines wide, four to twelve 

 inches long, more or less conduplicate. Panicle strict, continuous 

 or interrupted below, the appressed branches often in threes. 

 Lower empty glume four to five lines long, exceeding the second 

 glume, which is about the length of the floral glume; flowering 

 glume more orless scabrous on the back, three-awned; awns similar, 



