HITCHCOCK AND CHASE NORTH AMERICAN PANICUM. 



323 



circa stagnum, 6J a Sav: versus Oquechee. Flor: Ma. 478." Elliott gives "P. 

 dimidiatum, Walt. p. 72" as a synonym. 



Panicum walteri Muhl. Descr. Gram. 108. 1817, not Pursh, 1814. No locality nor 

 specimen is cited, but after the description the author adds "P. dimidiatum Walter 

 secundum Elliott." The specimen in the Muhlenberg Herbarium is labeled "Pani- 

 cum dimidiatum Walter, Ell. 478," and is evidently a duplicate of Elliott's specimen. 



Panicum hemitomon Schult. Mant. 2 : 227. 1824. Based on Panicum, walteri Muhl. 



Panicum carolinianum Spreng. Syst. Veg. 1 : 310. 1825. Sprengel's name appears 

 to be based on P. walteri Ell. as he cites after the brief description, ''Carol, austr. (P. 

 Walteri Ell.)." 



Panicum carinatum Torr. in Curtis, Bost. Journ. Nat. Hist. 1 : 137. 1835, not 

 Presl, 1830. "Hab. swamps," [around Wilmington, N. C.]. Curtis's specimen, 

 labeled "Panicum carinatum n. sp. Tor. mss. North Carolina. Mr. M. A. Ciu-tis," is 

 in the Torrey Herbarium. This is taken as the type since Torrey evidently intended 

 this as a new species, although "P. Walteri Ell." is cited as a synonym. 



Panicum digitarioides Car\)enter; Curtis, Amer. Journ. Sci. II. 7: 410. 1849, not 

 Rasp. 1833. This is mentioned as a synonym under P. carinatum Torr., Curtis 

 doubtless taking the name from specimens distributed by Carpenter under this name. 

 Such a specimen, collected by "W. M. Carpenter, prairie ponds, Opelousas & Attack- 

 opay La.," is in the Gray Herbarium. The species is later described by Steudela 

 under this name, his description being a translation of that of Curtis. 



Panicum curtisii Chapm. Fl. South. U. S. 573. 1860, not Steud. 1854. This is pro- 

 posed as a new name for "P. Walteri, Ell., not of Poiret nor Pursh. P. carinatum, Torr., 

 in Curtis's Plants, Wilmington, not of Presl.'' 



Brachiaria digitarioides Nash, in Britton, Man. 77. 1901. Based on Panicum digi- 

 tarioides Carpenter. 



DESCRIPTION. 



Plants aquatic or semiaquatic, with extensively creeping rootstglks often producing 

 numerous sterile shoots with overlapping, sometimes densely hirsute sheaths, and 

 blades 10 to 25 cm. long and 8 to 12 mm. wide, strigose on one or both surfaces; fertile 

 culms erect, 0.5 to 1.5 meters or more high, stout, usually hard, rarely rather soft and 

 flaccid about the water line, glabrous; submerged sheaths rather loose and papery, 

 often nodulose, aerial sheaths shorter than the internodes, close, glabrous or ciliate 

 on the margin, rarely hirsute toward the summit like those 

 of the sterile shoots, or the lower hirsute throughout; ligules 

 lacerate-ciliate, about 1 mm. long; blades ascending or 

 spreading, 10 to 25 cm. long, 7 to 15 mm. wide, acuminate, 

 rounded at base, firm, usually scabrous on the upper sur- 

 face, smooth below; panicles short-exserted, 15 to 30 cm. 

 long, very narrow, the branches erect or ascending, solitary 

 or 2 or 3 in a fascicle, the lower distant, gradually approxi- 

 mate upward, 2 to 10 cm. long, bearing short, appressed 

 branchlets or subsessile spikelets along the triquetrous, 

 scabrous rachis; spikelets 2.4 to 2.7 mm. long, 0.8 to 1 mm. 

 wide, lanceolate, acute, often slightly laterally compressed 

 (that is the glumes so keeled that the spikelet lies on its 

 side) ; first glume clasping, about half the length of spikelet, 

 acute, 3-nerved; second glume strongly keeled, somewhat boat-shaped, acute, 3 to 5- 

 nerved, slightly shorter than the 5-nerved sterile lemma, the latter inclosing a mem- 

 branaceous, scabrous-nerved paleaof nearly equal length ; fruit 2.3 to 2.5 mm. long, 0.7 

 mm. wide, slightly boat-shaped, elliptic, acute, smooth and shining, not rigid, the mar- 

 gins of the lemma inrolled toward the base only, the apex of the palea scarcely inclosed. 

 In this species the spikelets rarely perfect their grains. P. hemitomon departs some- 

 what from the typical Bpecies of Panicum in that the fruit is less rigid and the tip of 



Fig. 3 6 3 . — p. hemitomon. 

 From type specimen of P. 

 walteri Muhl. in the Muhlen- 

 berg Herbarium. 



a Syu. PI. Glum, 1:75. 1854. 



^ "^o^-x 



