POACEAE. 21 



1. A. Chapmaniana Nash. Stems 7-10 dm. tall: leaf -blades 1-2 dm. long: 

 panicle -~i dm. loiii^: spikelets 6-S mm. long, the flowering scale about 5 mm. 

 long, the central awn widely spreading, at right angles to the scale, 1.8-2.5 

 cm. long, the lateral awns erect, usually a little more than one-half as long as 

 the central awn. — IMnelands. 



2. A. purpurascens Poir. Stems 3-8 dm. tall: leaf -blades 5-20 cm. long: 

 panicle 1.5-3 dm. long: spikelets 9-12 mm. long, the flowering scale (5-8 mm. 

 long, the awns more or less spreading, especially the central one which is 1.5- 

 2.5 cm. long, the lateral awns from two-thirds as long to nearly equalling it. — 

 Pinelands.— F, K, (Bah.) 



3. A. stricta Michx. Stems 5-10 dm. tall: blades 5-30 cm. long, about 0.7 mm. 

 in diameter: panicle 1-3 dm. long, the short appressed branches in alternate 

 fascicles of 2 or 3 : spikelets 10-11 mm. long, the flowering scale 7-9 mm. long, 

 glabrous or sparingly hispidulous toward the summit, the awns more or less 

 spreading, the central one 7-11 mm. long, the lateral ones from f to nearly as 

 long. — Pinelands. — Wike-grass. 



24. MUHIiENBERGIA Schreb. Tufted or difl'use plants with terminal 



contracted or open panicles. Spikelets small. Scales 3 (or rarely 4), the outer 



2 persistent, membranous or hyaline, from minute to almost equalling the third 



scale, keeled, acute, mucronate or rarely short-awned, the second occasionally 



3-toothed, the third scale somewhat rigid, convolute at the apex, entire or 



rarely 2-toothed, obtuse, acute, mucronate to long-awned, the awn very often 



capillary, a fourth awned scale very rarely present. 



Empty scales awnless or awn-pointed. 1. M. capiUavis. 



Empty scales long-awned, the awn usually many times as long as 



the scale. 2. M. fllipcs. 



1. M. capillaris (Lam.) Trin. Stems wiry, 5-12 dm. tall: leaf-blades long and 

 narrow, often involute when dry, 1-3 mm. wide: panicle 1.5-4 dm. long, its 

 branches spreading or ascending: spikelets, exclusive of the awn, 3.5— i mm. 

 long, lanceolate, acuminate, the empty scales usually one-half as long as the 

 spikelet or less, commonly bearing a short awn. — Coastal sand-dunes. — F. K. 

 (Bah., Cuba.) 



2. M. filipes M. A. Curtis. Stem wiry, 5-10 dm. tall: leaf -blades long and 

 narrow, involute at least when dry, 1-2 mm. wide: panicle 2-3 dm. long, 

 often included at the base, its long branches spreading or ascending: spikelets, 

 exclusive of the awns, 4-5 mm. long, lanceolate, acuminate, the empty scale ^ 

 as long as the spikelet or less. — Everglades. 



25. STIPA L. Tufted plants with contracted or open panicles. Spikelets 

 narrow. Scales 3, the two outer persistent, narrow, keeled, acute, rarely awned, 

 the third scale tightly convolute, rigid, narrow, usually attenuate into a more 

 or less geniculate awn, (or rarely 2-toothed or shortly 2-cleft, with the awn 

 strict and arising between the teeth), which is often spiral or twisted at the 

 base, and generally deciduous at the articulation to the scales. 



1. S. avenacea L. Stems 3-8 dm. tall: leaf -blades involute-filiform, those of 

 the stem-leaves 7-13 cm. long: panicle 1-2 dm. long, its branches lax and 

 finally spreading: flowering scale shorter than the empty scales, black, hairy 

 at the base, and with a ring of short hairs at the top, the awn 4-7 cm. long, 

 bent, loosely sj)iral below. — Pinelands. — Black oat-grass. 



26. SPOEOBOLUS E. Br. Erect or diffuse plants with terminal panicles, 

 which are contracted or open and diffuse. Spikelets small. Scales 3, mem- 

 branous, acute or obtuse, the first shorter than the second. Stamens 2 or 3. 



— EUSH-GRASS. 



