Par* 3, 1915] POAC3AP) 



287 



the juncture with the blade in drying presenting a darkened triangle on each side; ligule mem- 

 branaceous, about 2 mm. long; blades flat, as much as 1 meter long and 6 cm. wide (the upper 

 and lower smaller), at base narrower than the sheath, gradually widening to about the middle, 

 narrowing rather abruptly to the acuminate apex, glabrous, striate, somewhat plicate, the 

 margins strongly serrulate; panicles as much as 60 cm. long and 40 cm. wide, the axis and 

 branches strongly several angled, scaberulous, the prominent pulvini minutely pubescent, the 

 branches stiffly spreading, naked at base, the lower in whorls, the short ultimate branchlets 

 and the pedicels appressed along the rather loose secondary branchlets, the pedicels mostly 

 1-2 mm. long; spikelets 2.5 mm. long, 0.9 mm. wide, nearly terete, pointed, glabrous; first 

 glume slightly more than half the length of the spikelet; second glume and sterile lemma 

 equal, exceeding the fruit, somewhat beaked beyond it; fruit 1.8 mm. long, 0.7 mm. wide, 

 narrowly obovate, smooth and shining, the lemma and palea indurated but the lemma-margins 

 flat. 



Type locality: Gatun Lake, Canal Zone. 



Distribution : Panama to Brazil. 



Illustration: Contr. U. S. Nat. Herb. 17: /. 143. 



208. Panicum hemitomon Schultes, in R. & S. Syst. Veg. Mant. 2: 



227. 1824. 



Panicum Walteri Muhl. Descr. Gram. 108. 1817. Not P. Walteri Pursh, 1814. 

 Panicum carolinianum Spreng. Syst. 1: 310. 1825. 



Panicum carinatum Torr.; M. A. Curt. Bost. Jour. Nat. Hist. 1: 137. 1835. Not P. carinatum 

 J. Presl, 1830. 



Panicum digitarioides Carpenter; M. A. Curt, Am. Jour. Sci. II. 7: 410, as synonym. 1849. Not 



P. digitarioides Rasp. 1833. 

 Panicum Curtisii Chapm. Fl. S. U. S. 573. 1860. Not P. Curtisii Steud. 1854. 

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



Plants aquatic or semiaquatic, with extensively creeping rootstocks often producing 

 numerous sterile shoots with overlapping, sometimes densely hirsute sheaths, and blades 10-25 

 cm. long and 8-12 mm. wide, strigose on one or both surfaces; fertile culms erect, 0.5-1.5 meters 

 or more high, stout, usually hard, glabrous; submerged leaf-sheaths rather loose and papery, 

 often nodulose, the aerial ones 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; ligule lacerate-ciliate, about 1 mm. long; blades ascending or spreading, 10-25 cm. 

 long, 7-15 mm. wide, acuminate, rounded at base, firm, usually scabrous on the upper surface, 

 smooth below; panicles sbort-exserted, 15-30 cm. long, very narrow, the branches erect or 

 ascending, solitary or 2 or 3 in a fascicle, the lower distant, gradually approxirhate upward, 2- 

 10 cm. long, bearing short, appressed branchlets or subsessile spikelets along the triquetrous, 

 scabrous rachis; spikelets 2.4-2.7 mm. long, 0.8-1 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, 3-5-nerved, slightly shorter than the 5 -nerved sterile lemma, 

 the latter inclosing a membranaceous, scabrous-nerved palea of nearly equal length; fruit 2.3- 

 2.5 mm. long, 0.7 mm. wide, slightly boat-shaped, elliptic, acute, smooth and shining, not rigid, 

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



Type locality: Charleston, South Carolina. 

 Distribution: Delaware to Florida, and west to eastern Texas. 



Illustrations: Contr. U. S. Nat. Herb. 15: /. 363; Britt. & Brown, 111. Fl./. 245 (as P. digitari- 

 oides); ed. 2./. 311. 



209. Panicum Tuerckheimii Hack. Allg. Bot. Zeits. 12 : 60. 1906. 



Plants perennial, from a firm knotty base with strong roots; culms erect or ascending, 

 simple, 30-50 cm. high, compressed, glabrous, with few to several long erect leaves borne at the 

 base, the nodes appressed-hirsute ; leaf -sheaths compressed-keeled, more or less hispidulous at 

 the juncture with the blade, otherwise glabrous, those of the basal leaves loose, overlapping, 

 those of the culm about as long as the internodes; ligule membranaceous-ciliate, scarcely 0.5 

 mm. long; blades thin, flat, 10-25 cm. long, 2-2.5 cm. wide, gradually tapering from about the 

 middle to an acuminate apex, the uppermost rather abruptly narrowed to a somewhat rounded 



