172 



CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



DESCRIPTION. 



Plants perennial, producing short knotty branching rhizomes as much as 4 cm. long; 

 culms erect, spreading, or prostrate, tufted or solitary, as much as 1 meter tall, sometimes 

 dwarfed, glabrous, usually scabrous below the panicle, the base usually hard and wiry, 

 often more slender than the upper part; 6heaths compressed-keeled, glabrous, some- 

 times scabrous toward the summit; ligule very short, densely ciliate; blades flat, 

 scabrous, often glaucous, and often more or less villous toward the base on the upper 

 surface, glabrous or somewhat scabrous beneath, mainly straight (not twisted as in C. 

 lutescens), as much as 20 cm. long and 8 mm. wide, usually narrower and shorter than 

 this; panicle long-exserted, erect, evenly cylindric, densely flowered, rounded or 

 truncate (not narrowed) at summit, 1 to 10 cm. long or in robust specimens longer, 4 to 8 



mm. thick (excluding the bristles), yel- 

 low, purple, tawny, or greenish, the axis 

 densely and softly pubescent; branches 

 pubescent like the axis, very short, about 

 1 mm. long to the single spikelet, bearing 

 about the middle a fascicle of irregular 

 branchlets, almost immediately dividing 

 into bristles; bristles several, mostly 8 to 

 12, yellow or purple, 1 to 3 times or even 

 as much as 6 times as long as the spike- 

 lets, antrorsely scabrous; spikelets 2 to 2.5 

 or even 3 mm. long, ovoid, plano-convex; 

 first glume about one-third as long as 

 spikelet, 3-nerved; second glume half to 

 two-thirds as long as spikelet, 5-nerved; 

 sterile lemma staminate or neuter, as long 

 as the spikelet, 5 to 7-nerved, the palea 

 well developed; fertile lemma trans- 

 versely rugose with close narrow ridges. 

 This species is exceedingly variable, 

 but after study of a great amount of ma- 

 terial and much field work it is impossible 

 to segregate coherent groups. The culms 

 are sometimes single, slender, and weak, 

 sometimes cespitose, sometimes stout, 

 much branched at base, spreading or pros- 

 trate; the blades vary in width, and the 

 panicles in length. Much of the differ- 

 ence in general appearance is due to the 

 color and length of the bristles. The bristles are long early in the season and in 

 cultivated soil. The differences appear not to be coordinated. In occasional 

 specimens the sterile lemma is indurate and rugose like the fertile lemma (Fort 

 Myers, Florida, Hitchcock 512; Virginia Beach, Virginia, Hitchcock 78). 



Sometimes the blades are very narrow, only 2 to 3 mm. wide, but otherwise the 

 form is not distinct (California: Fresno, Griffiths 4717. Pomona, Hitchcock in 1903. 

 Riverside, Reed 1186. Mexico: Monterrey, Hitchcock 55603). This has been called 

 C. gracilis. 1 



In Funck & Schlim 722 from Colombia (N. Y. Bot Gard. Herb.) the blades are 

 densely pilose on the upper surface and sparsely so beneath. 



1 U. S. Dept. Agr. Div. Agrost. Bull. 21: 15. 1900; Hitchcock, Mexican Grasses. 

 Contr. U. S. Nat. Herb. 17: 263. 1913. 



Fig. 41. 



-Chaetochloa geniculate. 

 Maryland. 



From Cliase 2981, 



