588 (JKAMIXK.K. ((illASS FAMILV.) 



•«. S. imberbis, H. & S. (Jlalnous; ciilins l^-.r liij,r|i; loaves linear, 

 8-10 loiiy;; spikes iiiR'ar-rvliiidricul, 2'-r/ long; liristlcs 4 - H, aliout twice 

 as long ius the spikelet; Hurct faiiitlv ruguloso. — Mauutce, Florida (Simpson), 

 and westward. 



■*- ■*- Sjilkes com/iiiiiHil. 



T). S. Viridis, Heauv. Culms smooth, l'^-3° iiigli ; leaves lanceolate- 

 linear, scaluims ; spikes cylindrical, comj)act, r-2'long; bristles 1-3- Horet 

 finely striate ami ilotted. — Cultivated ground. Introduced. 



0. S. COrrugata, Sciiulte.s. Culms, leaves, and slieatiis .scahrous; spikes 

 coni])a(t, cylindrical, .'i'-6' long, puri)ie ; i)ristle long, single; Horet strongly 

 rugose. — Dry sandy soil, Georgia and Florida. 



7. S. COmposita, Knnth? Culms smooth, 2° -4° high; leaves smooth- 

 isli, linear-lanceolate, 1"" long, the slieaths ciliate, bearded at the tiiroat ; spikes 

 loosely com])ound, 6'- 12' long; i)ristles long, single or in pairs; Horet ob- 

 scurely rngnlose. — Dry sandy soil along the west coa.st of P'lorida. 



8. S.- magna, Griseb. Culms smooth, 4° -8^ high; leaves long, .-scabrous, 

 i'-l' wide; spikes cylindrical, comjiact, 6'- 18' long; imstles 1-2; Horet 

 smooth and even. — Wet ground near the coast. 



9. CENCHRUS, L. Sand-spur. Cock-spur. 

 Spikelets as in I'anicum proper, l>ut enclosed, 1-5 togetiier, in a downy and 

 spiny or bristly, at length indurated and deciduous involucre, the.«e bur-like, 

 and arranged in a terminal spike. CliieHy annual grasses, witli branching 

 culms. Sjiines of the involucre barbed. 



1. C. eehinatus, L. Culms ascending, l°-2° long; leaves broadly 

 linear, 4'- G' long; involucres numerous, globular, spiny ai)ove, and with a 

 row of bristles above the base, 3 5-flowered. — Fields and waste ground, 

 rather rare. 



2. C. tribuloides, L. Culms ascending, i°-H° liigb ; leaves linear, 

 flat; involucres few, globular, the numerous sj)ines .spreading and reflexed, 

 mostly 3-flowered. — Fields and waste ground, too common. 



3. C. incertus, M. A. Curti.s. Culm .strict, erect or ascending (2° -3° 

 long); leaves linear, folded, the lower slieaths longer tlian the internodes; 

 spike cylindrical, mauy-flowered ; involucre naked and acute at base, the 10 or 

 II stout spines ciliate; spikelets geminate, smooth; sterih; flower triaudrous. 

 (C. strictus, Chnptn.) — Sandy coa.st, Florida to North Carolina. 



4. C. myosuroides, IIBK. Tall (4° -6° high); leaves long, rigid, con- 

 volute ; s])ikes cylindrical, denselv many-flowered ; involucre snuill, 1-flowered, 

 armed with 20, or more, slender spines or brist'es, as long as its strongly 

 nerved spikelet. (Panicum cenchroides, Ell.) — South Florida [Blodgetl), 

 Georgia (Elliott). 



10. PENNISETUM, IJich. 



Characters of Cenchrus, but the involucre composed of distinct scabrous bris- 

 tles, of whicli the interior are plumo.se below, and deciduous with the spikelets. 



1. P. setOSUm, Rich. Perennial, 2° -4° high; leaves linear, glabrous; 

 spikes cylindrical. 3' -6' long ; spikelets single; lowest glume minute or none. 

 — Lastero Bay, South Florida ( Garber). 



