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



1. Ctenium aromaticum (Walt.) 

 Wood. Toothache grass. (Fig. 750.) 

 Culms 1 to 1.5 m. tall, the old sheaths 

 persistent and fibrillose at base; 

 ligule about 1 mm. long; blades flat 

 or involute, stiff; spike 5 to 15 cm. 

 long; spikelets 5 to 7 mm. long. % 

 (Ctenium carolinianum Panzer.) — 

 Wet pine barrens, Coastal Plain, Vir- 

 ginia to Florida and Louisiana. The 

 roots spicy when freshly dug. Fur- 

 nishes fair cattle forage in moist pine 

 barrens of Florida. 



2. Ctenium fioridanum (Hitchc.) 

 Hitchc. (Fig. 751.) Differs from C. 

 aromaticum in having creeping scaly 

 rhizomes, ligule 2 to 3 mm. long, sec- 

 ond glumes with longer, more slender 

 awns and without glands or with only 

 obscure ones. % (Erroneously re- 

 ferred by American authors to Cam- 

 pulosus chapadensis Trin.) — Moist 

 pine barrens, Florida. 



X^r " 



Figure 751. — Ctenium fioridanum. Plant, X 1; glumes 

 and florets, X 5. (Combs 702a, Fla.) 



109. GYMNOPOGON Beauv. 



Spikelets 1- or rarely 2- or 3-flowered, nearly sessile, appressed and usually 

 remote in 2 rows along one side of a slender continuous rachis, the rachilla 

 disarticulating above the glumes and prolonged behind the 1 or more fertile 

 florets as a slender stipe, bearing a rudiment of a floret, this sometimes with 

 1 or 2 slender awns; glumes narrow, acuminate, 1-nerved, usuahy longer than 

 the floret; lemmas narrow, 3-nerved, the lateral nerves near the margin, the 

 apex minutely bifid, bearing between the teeth a slender awn, rarely awnless. 

 Perennials or rarely annuals (ours perennial), with short, stiff, flat blades, 

 often folded in drying, numerous long slender divergent or reflexed spikes, 

 approximate on a slender stiff axis. Type species, Gymnopogon racemosus 

 Beauv. (G. ambiguus). Name from Greek gumnos, naked, and pogon, beard, 

 alluding to the naked prolongation of the rachilla. 



Awn 4 to 6 mm. long, longer than the lemma 1. G. ambiguus. 



Awn 1 to 3 mm. long, usually shorter than the lemma. 



Spikelets 1 -flowered; spikes floriferous only in the upper half 2. G. brevifolius. 



Spikelets 2- to 3-flowered; spikes floriferous to the base. 



Spikes stiffly ascending, usually more than 20; glumes widely spreading even on young 



spikelets 3. G. chapmanianus. 



Spikes spreading or reflexed, usually fewer than 15; glumes not spreading, even in 

 mature spikelets 4. G. floridanus. 



1. Gymnopogon ambiguus (Michx.) 

 B. S. P. (Fig. 752.) Culms 30 to 60 

 cm. tall in small clumps with short 

 scaly rhizomes, suberect to spread- 

 ing, rigid, sparingly branching; leaves 



numerous, approximate with overlap- 

 ping sheaths, or the lower rather dis- 

 tant; blades spreading, 5 to 15 mm., 

 mostly about 10 mm. wide, the base 



