MANUAL OF THE GRASSES OF THE UNITED STATES 



751 



Upper sheaths inflated, overlapping, conspicuous 29. A. elliottii. 



Upper sheaths not inflated, overlapping, nor conspicuous. 



Spikelets 4 mm. long; racemes very flexuous, the rachis joints nearly as long 



as the spikelets 29. A. subtenuis. 



Spikelets 5 to 7 mm. long; racemes slightly or not at all flexuous, the rachis 

 joints distinctly shorter than the spikelets. 

 Sessile spikelets about 5 mm. long, about 0.5 mm. wide, the glume deeply 

 grooved ; hairs of racemes not obscuring the spikelets. 



19. A. ARCTATUS. 



Sessile spikelets somewhat more than 5 mm. long, 1 to 1.5 mm. wide, the 



glume concave but not grooved; hairs of racemes conspicuous to 



copious. 



Racemes copiously long-villous, the hairs about twice as long as the 



spikelet and obscuring it ; first glume of sessile spikelet nerveless and 



glabrous between the keels 18. A. ternarius. 



Racemes not copiously villous, the hairs about as long as the spikelet, not 

 obscuring it; first glume of sessile spikelet scabrous and often 2- 

 nerved between the keels 17. A. cabanisii. 



Section 3. A?nphUophis 



Racemes 3 to 7, not conspicuously woolly; pedicellate spikelet about as large as the sessile 



one. Sessile sp'kelet often pitted 31. A. wrightii. 



Racemes few to many, conspicuously woolly; pedicellate spikelet reduced. 

 Panicle subflabellate, often short-exserted or included at base in a dilated sheath; racemes 

 few to many on a relatively short axis; spikelets 5 to 6 mm. long. 



33. A. BARBINODIS. 



Panicle oblong, usually long-exserted ; racemes numerous on a long axis; spikelets 3.5 to 

 6 mm. long. 



First glume of sessile spikelet pitted 32. A. perforates. 



First glume of sessile spikelet not pitted. 



Spikelets awned 34. A. saccharoides. 



Spikelets awnless 35. A. exaristatus. 



Section 1. Schizachyrium (Nees) Trin. 



Branching perennials; racemes soli- 

 tary on each peduncle; rachis 

 joints tapering to base, the apex 

 oblique and hollow; sessile spike- 

 lets awned, the awns twisted, 

 geniculate. 



1. Andropogon gracilis Spreng. 

 (Fig. 1139.) Culms slender, wiry, 

 densely tufted, erect, glabrous, 20 to 

 60 cm. tall; blades terete, filiform; 

 peduncles few to several, filiform, 

 long-exserted, with a tuft of long 

 white hairs at summit; raceme 2 to 

 4 cm. long, silvery white; rachis 

 slender, flexuous, copiously long- 

 villous; sessile spikelet about 5 mm. 

 long, the awn 1 to 2 cm. long; pedicel- 

 late spikelet reduced to an awned 

 or awnless glume, the pedicel very 

 villous. % — Rocky pine woods 

 southern Florida; West Indies. 



2. Andropogon tener (Nees) Kunth. 

 (Fig. 1140.) Culms slender, tufted, 

 sometimes reclining or decumbent, 

 60 to 100 cm. long, the upper half 



Figtjbe 1139. — Andropogon gracilis, X 1. (Hitchcock 

 682, Fla.) 



rather sparingly branching; blades 

 scarcely 1 mm. wide, flat or loosely 

 involute, often sparingly long-pilose 

 on upper surface near base; raceme 

 finally long-exserted, slender, sub- 

 terete, glabrous, 2 to 6 cm. long; 



