HITCHCOCK AND CHASE NORTH AMERICAN PANICUM. 



Ill 



Rachises bearing slender bristles (these wanting in 

 exceptional specimens); blades broadest near 

 the cordate or truncate base; nodes usually 



villous 59. P. pilosum. 



Rachises without bristles; blades narrowed toward 



the base; nodes glabrous 60. P. laxum. 



Panicle branches not racemose; blades scarcely wider 

 than their sheaths; the sterile palea conspicuously 

 enlarged. 

 Spikelets 3 mm. long, congested; panicles dark pur- 

 ple 63. P. cupreum. 



Spikelets not over 2.4 mm. long; panicles green or 

 pale. 

 Panicle branches spikelet or branchlet-bearing 

 along the upper half or toward the ends 



only 62. P\ hians. 



Panicle branches branchlet-bearing throughout 



their length or nearly so 61. P. exiguifiorum. 



57. Panicum longum nom. nov. 



Panicum munitum Trim; Steud. Nom. Bot. ed. 2. 2: 260. 1841. This nomen 

 nudum is credited to "Trin. mpt. Mexico." A specimen of P. longum collected 

 near Jalapa by Schiede and Deppe, no. 674, and listed by Schlechtendahl « as num- 

 ber 898 "Panicum proximum piloso Sw.," was examined at Halle. The sheet is 

 marked "Panicum munitum" by Trinius, and may be the type of this name, but 

 since the species was not described by Trinius P. longum is here based on Scribner's 

 type, Pringle 8195. 



Panicum pilosum macranthum Scribn. U. S. Dept. Agr. Div. Agrost. Circ. 19: 1. 

 1900, not P. macranthum Trin. 1826. "Swamps near Jalapa, State of Vera Cruz, 

 altitude 1,230 m., May 21. C. G. Pringle, No. 8195. 1899." The type, in the 

 National Herbarium, is a slender plant 150 cm. high. 



DESCRIPTION. 



Plants perennial, ascending or spreading from a more or less geniculate base; culms 

 rather robust, 1. 2 to 2 meters long, simple or sparingly branching from the lower nodes, 

 glabrous, the nodes glabrous ; sheaths nearly as long as the 

 internodes or overlapping, papillose or papillose-hirsute 

 (the greater number of papillae without hairs) ; ligule about 

 0.5 mm. long; blades ascending or spreading, 10 to 25 cm. 

 long, 6 to 12 mm. wide, linear, scarcely narrowed to the 

 rounded base, very sparsely papillose-pilose on the upper 

 surface, glabrous beneath or with a few papillae; panicles 

 short-exserted or included at the base, 20 to 25 cm. long, 

 2 to 5 cm. wide, the branches raceme-like, the lower soli- 

 tary, distant, the middle and upper opposite or verticillate, 

 the rachises and upper part of the main axis with stiff hairs 

 slightly exceeding the short-pediceled, secund, approxi- 

 mate, but scarcely crowded spikelets; spikelets mostly in pairs, 2.5 mm. long, 0.9 

 mm. wide, pointed, strongly nerved, the nerves minutely scabrous toward the 

 summit; first glume about half the length of the spikelet, pointed; second glume 

 shorter than the sterile lemma, both slightly exceeding the fruit, the sterile palea 



Fig. 106.— P. longum. From 

 type specimen of P. pilosum 

 macranthum Scribn. 



a Linnaea 6 : 35. 1831. 



