Genus 17. 



GRASS FAMILY. 



137 



Ligule y 2 " long or more ; culms, at least at the base, pubescent 

 with long stiff appressed hairs. 

 Blades glabrous on the upper surface ; spikelets about 



W long. 46. P. leucothrix. 



Blades pubescent on the upper surface with long hairs ; 

 spikelets exceeding l /i" long. 52. P. meridionale. 

 Spikelets 1" long or more. 

 Pubescence spreading. 



Autumnal state erect ; pubescence papillose-hispid ; upper sur- 

 face of blades glabrous or nearly so. 48. P. scoparioides. 

 Autumnal state prostrate ; pubescence hirsute ; upper surface of 

 blades long-hairy. 49. P. villosissimum. 



Pubescence not spreading. 



Panicle ij4'-2' long, oblong, dense; spikelets 1" long. 



56. P. Addisoni. 

 Panicle 2j4'-3j4' long, broadly ovoid, open; spikelets iJ4" 

 long. 57. P. Commonsianum. 



Spikelets zyi" long or more. 



Spikelets hirsute with long hairs, the first scale usually over J4 as long as the 



spikelet, often narrow and attenuate. 61. P. Liebergii. 



Spikelets glabrous, or if pubescent the hairs short. 

 Leaf-blades glabrous, at least on one surafce. 



Panicle narrow, its branches usually appressed. 64. P. xanthophysum. 



Panicle broad, nearly as wide as long. 



Spikelets ij4" long; blades commonly much elongated. 



Blades rough, usually erect, not ciliate. 70. P. aculeatum. 



Blades smooth, spreading, ciliate. 73. P. mutabile. 



Spikelets over 1 J4" long; blades not elongated. 



Blades softly and densely pubescent beneath with short hairs. 



Culms papillose-hispid with appressed or ascending hairs ; blades 



usually 6" wide or more. 66. P. Ravenelii. 



Culms villous ; blades 5" wide or less. 63. P. oligosanthes. 



Blades glabrous, or rarely puberulent beneath. 



62. P. Scribnerianum. 

 Leaf-blades pubescent on both surfaces. 



Blades erect, less than 3" wide; pubescence hispid. 65. P. Wilcoxianum. 

 Blades spreading, exceeding 3" wide ; pubescence soft. 68. P. malacophyllum. 

 Middle blades of the main culm more than 8" wide, usually cordate and clasping at the base. 

 Spikelets less than 1 yi " long. 



Blades glabrous on both surfaces. 



Spikelets less than 1" long ; culms simple. 32. P. polyanthes. 



Spikelets more than 1" long; panicle nearly as broad as long; culms branched. 

 Sheaths papillose-hispid, especially the terminal ones. 76. P. clandestinum. 



Sheaths glabrous. 72. P. commutatum. 



Blades densely villous on both surfaces. 67. P. scoparium. 



Spikelets ij^" long or more. 



Panicle narrow, its branches appressed, rarely a little spreading. 64. P. xanthophysum. 

 Panicle open, its branches spreading. 



Blades lanceolate, thick, glabrous above, densely pubescent on the lower surface with 



short spreading hairs. 66. P. Ravenelii. 



Blades thin, ovate-lanceolate, glabrous, or sometimes sparsely pubescent. 

 Nodes barbed. 75. P. Boscii. 



Nodes naked. 



Spikelets ij4" long; blades rarely exceeding 8" wide. 73. P. mutabile, 

 Spikelets nearly 2" long ; blades exceeding 10" wide. 74. P. latifolium. 



i. Panicum hemitomon Schult. Maiden-cane. 

 Simpson's-grass. Fig. 311. 



Panicum hemitomon Schult. Mant. 2 : 227. 1824. 

 Panicum carinatum Torr. Bost. Journ. Nat, Hist. 1 : 



1 37- '835. Not Presl, 1830. 

 Panicum digitarioides Carpenter ; Steud. Syn. PI. Gram. 



75- 1855- 

 Panicum Curtisii Chapm. FI. S. States, 573. i860. 



Not Steud. 1855. 

 Brachiaria digitarioides Nash, in Britt. Man. 77. 1901. 



Glabrous, culms erect from a long and stout creep- 

 ing rootstock, 3°-5° tall, simple, stout, smooth. 

 Sheaths smooth; blades 4'-io' long, 4"-8" wide, 

 long-acuminate; panicle linear, 6'-i2' long, its 

 branches 1/-3' long, erect; spikelets about ii" long, 

 ovate, acute; first scale about one^half as long as 

 the spikelet, acute, 3-nerved; second about 1" long, 

 S-nerved and a little exceeded by the 3-nerved third 

 one; --the fourth slightly shorter than the third. 



In water, New Jersey to Florida and Texas. July-Aug. 



