728 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



Panicle oblong, usually long-exserted; racemes numerous on a long axis; spike- 

 lets 3.5 to 6 mm long. 



First glume of sessile spikelet pitted 29. A. perforates. 



First glume of sessile spikelet not pitted. 



Spikelets awned 31. A. saccharoides. 



Spikelets awnless 32. A. exaristatus. 



Section 1. Schizachyrium (Nees) Trin. 



Branching perennials; racemes solitary on each peduncle; rachis 



joints tapering to base, the apex obliquely cup-shaped; sessile 



spikelets awned, the awns twisted, geniculate. 



1. Andropogon gracilis Spreng. (Fig. 1620.) 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 ; 

 pedicellate spikelet reduced to an 

 awned or awnless glume, the pedi- 

 cel very villous. % — Rocky 

 pine woods, southern Florida; 

 West Indies. 



2. Andropogon tener (Nees) 

 Kunth. (Fig. 1621.) Culms 

 slender, tufted, sometimes re- 

 clining or decumbent, 60 to 100 

 cm long, the upper half 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, subterete, glabrous, 2 to 6 

 cm long; sessile spikelet about 4 nim long, the awn 7 to 10 mm long. 

 % — Dry pine woods and prairies, Coastal Plain, Georgia to Florida 

 and Texas; tropical America (fig. 1622). 



3. Andropogon hirtifiorus (Nees) Kunth. (Fig. 1623.) Culms 

 tufted, 60 to 120 cm tall, erect, reddish, the upper half sparingly 



branching; foliage often glaucous, the blades 2 

 to 4 mm wide; raceme 6 to 10 cm long, the 

 base often included in the somewhat dilated 

 sheath, the rachis joints, pedicels, and first 

 glume of sessile spikelet pubescent, the rachis 

 straight; sessile spikelet about 6 mm long, the 

 awn 10 to 15 mm long; pedicellate spikelets 

 much reduced, short-awned. % (A. oligo- 

 stachyum Chapm.) — Pine woods, southern 

 Georgia and Florida; tropical America (fig. 1624). Andropogon 

 hirtiflorus var. feensis (Fourn.) Hack. Blades scabrous; sessile 

 spikelet as much as 9 mm long, the first glume minutely papillose, the 



Figure 1620.— Andropogon gra 

 cilis, X 

 Fla.) 



1. (Hitchcock 682, 



Figure 1021. — • 

 Andropogon tener, 

 X 1. (Rolfs 986, 

 Fla.) 



Figure 1622. — Distribution of 

 Andropogon tener. 



