HITCHCOCK AND CHASE NORTH AMERICAN PANICUM. 



279 



Spikelets 3.2 to 3.3 mm. long; blades firm; 

 sheaths or some of them more or less 

 ** hispid 171. P. scribnerianum. 



Spikelets not over 3 mm. long; blades rather 

 thin ; sheaths or some of them glabrous 

 or sparsely hispid 170. P. helleri. 



168. Panicum wilcoxianum Vasey. 



Panicum wilcoxianum Vasey, U. S. Dept. Agr. Div. Bot. Bull. 8: 32. 1889. "Ne- 

 braska (Dr. T. E. Wilcox)." The type, in the National Herbarium, consists of several 

 vernal culms beginning to branch, 13 to 17 cm. high, with scarcely mature primary 

 panicles. On the sheet is written in Vasey's hand, "Panicum Wilcoxianum, Vasey 

 n. sp., Niobrara Ft., Nebraska. Dr. T. E. W T ilcox, 1888." 



DESCRIPTION. 



Fig. 313.— P. wilcoxianum. From type specimen. 



Vernal form dull green; culms usually in dense tufts, erect, 10 to 25 cm. high, copi- 

 ously papillose-hirsute, as are the rather loose, usually overlapping sheaths; ligules 

 about 1 mm. long; blades firm, erect or ascending, 5 to 8 cm. long, 3 to 6 mm. wide, 



broadest toward the base (this scarcely 

 wider than the wide sheath), commonly 

 involute-acuminate, long-hirsute on both 

 surfaces; panicles finally exserted, often 

 equaled or exceeded by the upper blades, 

 2 to 5 cm. long, about half as wide, or some- 

 times more expanded at anthesis, rather 

 densely flowered; spikelets 2.7 to 3 mm. 

 long, 1.5 mm. wide, obovate-elliptic, papil- 

 lose-pubescent ; first glume about one-third 

 as long as the spikelet, pointed or obtuse; 

 second glume slightly shorter than the fruit 

 and sterile lemma; fruit 2.4 to 2.5 mm. long, 1.3 to 1.4 mm. wide, elliptic. 



Autumnal form branching from all the nodes, forming bushy tufts with rigid, erect 

 blades much overtopping the reduced panicles; branches appearing early, usually 

 before the maturity of the primary 

 panicles; secondary spikelets usually 

 more turgid than those of the primary 

 panicles. 



DISTRIBUTION. 



Prairies, Manitoba to North Dakota 

 and south to Iowa and Kansas. 



Minnesota : Winona, Holzinger 28 



in part (Biltmore Herb.). 

 Manitoba: Sewell, Macoun 13227. 

 North Dakota: Towner, Lunell 



in 1908. 

 South Dakota: Brookings, Williams in 1891, E. N. Wilcox 14; Roberts County, 



S. D. Agr. Col. & Exp. Sta. 4167; Rosebud, Wallace in 1896; Jamesville, 



Bruce 80. 

 Iowa: Missouri Valley, Pammel 3198; Gilbert Station, Carver in 1894. 



Fig. 314.— Distribution of P. wilcoxianum. 



