328 



CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Fig. 369.— Distribution of P. gymnocarpon. 



somewhat scattered clusters; spikelets 6 to 7 mm. long, about 1.2 mm. wide, 

 and, by the spreading of the glumes, about twice as thick, strongly nerved; first 

 glume nearly as long as the sterile lemma, acuminate-pointed, the second 

 glume exceeding the sterile lemma, both much exceeding the fruit and at 

 maturity spreading and exposing it, acuminate-pointed, the summit of the lemma 

 arcuate, the sterile palea obsolete; 

 fruit 2 mm. long, 1 mm. wide, ob- 

 ovate, stipitate, smooth and shining. 



DISTRIBUTION. 



Ditches and muddy banks of streams 

 and lakes, Georgia and Florida to Texas. 

 Georgia: Americus, Harper 522. 

 Florida: Burnside, Combs 1426; 



without locality, Chapman, 



Rugel 599, Simpson in 1890. 

 Alabama: Mobile, Mohr in 1887. 

 Mississippi: Saratoga, Tracy 8396. 

 Louisiana: Plaquemines Parish, Langlois 47, 151; Chalmette, Tracy 7400; 



Alexandria, Hale; Natchitoches, Ball 157; Lake Charles, Chase 4407. 

 Texas: Harrisburg, Joor in 1875; Mineola, Reverchon 2235 ; Columbia, Bush 1498; 



Hempstead, Plank 9; Waller County, Thurow 17, and in 1889. 



26 A. Panicum decolorans H. B. K. 



Panicum decolorans H. B. K. Nov. Gen. & Sp. 1: 100. 1815. "Crescit in temperatis, 

 apricis regni Mexicani prope Queretaro, alt. 995 hexap." The type specimen from the 

 Bonpland Herbarium in the Paris Herbarium, bearing the published data, consists of 



two pieces of a culm with flat blades, one 

 with a narrow terminal panicle about 18 

 cm. long. The spikelets are 5 to 5.2 

 mm. long. 



Plants tinged with purple, branching 

 from the base; culms ascending or erect, 

 usually from a geniculate base, simple or 

 bearing simple, usually sterile branches 

 from the lower one or two nodes, strongly 

 striate or almost grooved, glabrous to 

 sparsely papillose-hispidulous, the nodes 

 appressed-pubescent or glabrous; sheaths 

 short, but sometimes overlapping on the 

 shortened lower internodes, glabrous to 

 sparsely papillose-hispid, ciliate; ligules 

 membranaceous-fimbriate, hardly 1 mm. 

 long; blades 8 to 15 cm. long, 7 to 10 mm. 

 wide, flat, glabrous on both surfaces or with a few scattered papillae, these with or 

 without short, stiff hairs; panicles finally exserted, 10 to 18 cm. long, usually not 

 more than one-third, but sometimes as much as two-thirds as wide, the rather long 

 branches usually narrowly ascending, the short-pediceled spikelets somewhat crowded 

 on approximate, short, appressed branchlets; spikelets 4.5 to 5.2 mm. long, 1.6 mm. 

 wide, pointed; first glume less than half the length of the spikelet, acute; second 

 glume and sterile lemma subequal, exceeding the fruit and pointed beyond it; fruit 

 2.8 to 3.2 mm. long, 1.5 mm. wide. 



Fig. 370.— P. decolorans. From type specimen. 



