ELISHA MITCHELL SCIENTIFIC SOCIETY. 27 
Spikelets scarcely 4” longi ts ite at. tise. 47. P. leucothrix. 
Spikelets 4°’—1” long, obovate. 
Panicle oblong, its branches erect or ascending 
Katonii. 
Panicle broadly ovate, its branches spreading. 
Leaves erect, panicle 1%’ long or less 49, P. Columbianuin, 
Leaves ascending, panicle 1’—3’ long .... 50. P. nitiduim. 
Sheaths more or less pubescent and often stems and leaves, 
Leaves 4”—8” wide, spikelets 4”—1\” long. 
Strict, 2ft.—3ft tall, pubescence villous .. 51. P. Huachucae. 
Stems ascending, geniculate at base. . 
Pubescence pilose, velvety, spikelets oval 1%”’ long 52, P. 
viscidum. 
Pubescence villous, ascending, spikelets obovate, 1” 
bone. Noire s Aatetge 3 sia tee tart vee. 03. P. ciliiferum. 
Stems erect, at length decumbent, leaves appressed pubes- 
cent beneath. 
Spikelets %’’ long, leaves, ascending 54. P. tsugetorum. 
Spikelets 4” long, leaves spreading 55 P. Tennesseense. 
Leaves 2’’—4”" wide, spreading or ascending, spikelets about 1” 
long. 
Lower branches of panicle BSCE, , pubescence hirsute-pa- 
Pre ROR Sia sates eR 5 fra wlth Mh eiate pa 56. P. Atlanticum. 
Lower branches of panicle spreading. 
Strict, leaves spreading, basal leaves not prominent. 
Pubescence rough, ascending, spikelets nearly spher- 
ical or broadly elliptical ........ 57. P. scoparioide. 
Pubescence, villous, long, spreading spikelets ellip- 
tic 
mika: ale chs aa iene RAI bead ts 58. P. villosissimuim. 
Pubescence softer, ascending spikelets elliptic 59. P. 
pubescens. 
Strict ; leaves erect or ascending. 
Leaves lanceolate, panicle as broad as fies 
Pubescence ascending-appressed .... 60. P. Com- 
monsianum. 
Pubescence ascending or spreadiug...... GAL 
haemacarpon. 
Leaves linear-lanceolate, panicle sploue pao 62. P 
arenicolum, 
Tufted, stems soon reclining; few-leaved, basal leaves 
very numerous and long... .....45-.: 63. P. laxiflorum. 
Leaves 2”—4” wide, spikelets 4”—%” long. 
Lower branches of panicle ascending 64. P. lanuginosuim., 
Lower branches of panicle wide-spreading. 
Sheaths papillose-hirsute ........ 65. P. implicatum., 
Lower sheaths velvety, and nodes barbed .... 66. P. 
annulum. 
