PANIC E.E. 159 



Culms stout, 90-120 cm. liigli. Sheatlis hispid; ligule a fringe 

 of hairs; blades glal)rouH, folded, grooved. 30-120 cm. long, 3-4 

 cm. wide, acuminate at both ends. Panicle dense, lanceolate, the 

 apex nodding, 30-60 cm. long, the longest rays 2.5-3 cm. long, the 

 branches and pedicels bearing scattered slender bristles 1-3 cm. 

 long. Spikelets elliptical, acute, 3 mm. long, first empty glume 

 ovate, 3-nerved, 1.5 mm. long, second ovate, obtuse or subacute, 

 5-nerved, 2 mm. long, the third ovate-acute, 5-nerved, a little ex- 

 ceeding the acute lloret. Floral glume and palea not very firm. 

 Near streams. 



Mexico (San Ijuis Potosi), Pritigle 3921. 



31. (13). Cenchrus L. Sp. PI. 1049 (1753). Linn. Coroll. 

 Gen. 20(1737). 7i'a;T//* Adans. Fam. 2 : 35 (17(33). Echisacluis 

 Neck. Elem. 3:228 (1790). 



Spikelets with one terminal perfect llower and sometimes a 

 staminate one below it, not awned, single or 2-3 together within 

 an ovoid or glol)ular involucre of numerous bristles, the inner ones 

 usiuilly broad and llattened, connected at tlic base and ha.'<k'ned 

 around the fruit; the involucres sessile or pedicellate in a simple 

 spike or raceme and falling off with the spikelets. (ilunies 4. the 

 outer one much smaller or minute, the second and third nearly 

 equal or the second shoi'ter; a palea and sometimes 3 stanu'ns in 

 the third iloral glume of the perfect floret rather firm, but not so 

 hard as in most species of Pdiiicion. Styles mostly shortly united 

 at the l)ase. Grain enclosed, but not adherent to the glume and 

 palea. 



There are about 12 si)ecies of annuals or perennials, widely 

 scattered over the warmer regions of the New and the Old World. 

 Most of them are troublesome weeds on sandy land. 



Cenchrus is perhaps most nearly related to Pennisetiim, also re- 

 lated to Chamwraj)}) is xiwiX Panicion. 



a. Spike cylindrical, burs containing 1 spikelet which is as 

 long as the spines 1 



a. Spike cylindrical, burs containing 2 spikelets, blades con- 

 duplicate 3 



