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



16. Andropogon arctatus Chapm. (Fig. 1643.) Resembling 

 A. ternarius; culms 1 to 1.5 m tall; the blades often wider and firmer; 

 branches of the inflorescence rather more slender; racemes 3 to 5 cm 

 long, tawny, sessile spikelets 4 to 5 mm long, brown, the awn 1 to 5 cm 

 long; first glume concave, the pale or tawny hairs of rachis and pedicels 

 snorter and less copious than in A. ternarius; 

 sessile spikelet 5 mm long, 0.5 mm wide, the 

 glume grooved; stamen 1. % — Low pine 

 woods, Florida. 



17. Andropogon floridanus Scribn. (Fig. 

 1644.) Culms often stout, 1 to 1.8 m tall; the 

 upper one-third to half bearing long slender 

 branches; blades elongate, 2 to 6 mm wide; in- 

 florescence loosely subcorymbose, of usually 

 numerous pairs of silvery white to creamy racemes on subcapillary 

 peduncles mostly 2 to 8 cm long, included in very slender spathes or 

 exserted, the ultimate branchlets filiform, often long-cilia te toward 

 the summit; racemes 3 to 4 cm long, the slender rachis not flexuous, 

 the joints a little shorter than the spikelets, rather copiously long- 

 villous; sessile spikelets 4 to 4.5 mm long, the delicate awn straight, 



Figure 1642.— Distribution of 

 Andropogon ternarius. 



Figure 1643. — Andropogon arctatus, X 1. 

 (Chapman, Fla.) 



Figure 1644.— Andropogon floridanus, X 1. 

 (Type coll.) 



6 to 10 mm long ; pedicel long- villous, the spikelet obsolete. % — Low 

 pine woods, Florida. An occasional peduncle bears 3 racemes. 



18. Andropogon tracyi Nash. (Fig. 1645.) Culms in small tufts, 

 slender, erect, the upper third sparingly branching; sheaths keeled, 

 narrow, glabrous or nearly so; blades 2 to 3 mm wide, sometimes 

 ciliate toward base; inflorescence of 8 to 10 relatively distant racemes, 

 the slender ultimate branches often recurved, the dilated spathes 4 to 

 6 cm long, attenuate below, the enclosed peduncle 1 to 3 cm long; 



