120 



CONTEIBUTIONS FROM THE NATIONAL HERBARIXJM. 



O 63. Panicum cupreum nom . nov. 



Panicum Mans purpurascens Scribn. Proc. Acad. Phila. 1891: 296. 1891, no t P . 

 -pttrpwrtstms-^^-Br-^Kv-iM^ "(3449) [Pringle] * * * Wet hollows in prairies of 

 Flor de Maria, State of Mexico. September 4." The type is in Hitchcock's herba- 

 rium. It was collected in 1890. 



Fig. 113 .— P . cupreum. 

 From tjrpe specimen of 

 P. Mans purpurascens 

 Scribn. 



DESCRIPTION. 



Plants perennial, in small tufts; culms simple, erect, 40 to 60 cm. high, slender, 

 T/iry, glabrous; leaves somewhat clustered at the base, the sheaths keeled, glabrous, 

 the lower OA^erlapping, the upper shorter than the inter- 

 nodes; ligules fimbriate, scarcely 0.5 mm. long; blades 5 to 15 

 cm. long, 2 to 4 mm. wide, at the base scarcely as wide as the 

 sheaths, erect or ascending, folded and more or less twisted, 

 glabrous or with a few long hairs on the upper surface at the 

 base; panicles very long-exeerted, 3 to 11 cm. long, dark pur- 

 ple, composed of a few distant, slender, appressed or ascending 

 branches, naked about half their length, bearing short, 

 crowded branchlets with densely clustered spikelets along the 

 upper half or toward the ends; spikelets 3 mm. long, about 

 1.2 mm. wide, and at maturity nearly twice as thick, rather 

 strongly nerved ; first glume one-third the length of the spike- 

 let or less, obtuse, concave along the midnerve; second glume 

 and sterile lemma equal, exceeded by the enlarged sterile 

 palea, the lemma strongly concave along the midnerve below; 

 fruit 2.4 mm. long, 0.8 mm. wide, the margins of the lemma more inrolled than in 

 P. Mans, the apex tipped with a minute bit of hyaline membrane. 



This species is allied to P. Mans, from which it is chiefly distinguished by the 

 larger, more congested spikelets, with shorter, concave first glume and concave sterile 

 lemma. 



The type collection, Pringle's no. 3449, two specimens of which we have seen, is 

 the only one known of this species. 



Stolonifera. — Plants perennial, decumbent at base or widely creeping and rooting 

 at the nodes; culms branching, pubescent in lines or glabrate; sheaths (except 

 in P. higlandulare) with a dense line of pubescence at the summit; ligules mem- 

 branaceous, nearly obsolete; blades lanceolate or ovate-lanceolate, acuminate 

 and with a pubescent, petiole-like base; panicles composed of few to several 

 short, densely-flowered racemes along a main axis, a tuft of pubescence at the bases 

 of the rachises; spikelets short-pediceled, mostly in 2's, secund along the lower 

 side of the rachis, strongly nerved, the second glume and sterile lemma scabrous 

 on the midnerves toward the summit, exceeding the smooth and shining fruit. 

 Spikelets hispid and with 2 crateriform glands on the sterile 

 lemma; second glume and sterile lemma not boat-shaped. 

 Spikelets not over 2 mm. long; blades not over 4 cm. long. 66. P. pulchellum. 



Spikelets 3.6 mm. long; blades 4 to 10 cm. long 67. P. higlandulare. 



Spikelets glabrous, glandless; second glume and sterile lemma 

 boat-shaped. 

 Blades not over 5 cm., usually 2 or 3 cm. long; second 

 glume rather blunt and shorter than the sterile 



lemma 64. P. stoloniferum. 



Blades 5 to 11 cm. long; second glume acute, nearly equal- 

 ing the sterile lemma 65. P.frondescens. 



