Part 3, 1915] POACEAB 



227 



simple, robust, tough, and hard; leaf -sheaths longer than the rather short lower internodes, 

 usually shorter than the upper ones, often ciliate, sometimes villous at the throat; ligule dense, 

 2-4 mm. long; blades ascending, 10-60 cm. long, 3-15 mm. wide, slightly narrowed toward the 

 base, and gradually long-acuminate, flat, sometimes pilose on the upper surface toward the base, 

 rarely to the apex, the margins scabrous; panicles long-exserted, 15-50 cm. long, mostly one 

 third to half as wide, but sometimes contracted, or very loose and nearly as wide as long, usually 

 many-flowered, the slender, scabrous, usually fascicled branches ascending or spreading, naked 

 at base, repeatedly branching along the upper half or two thirds; spikelets rather short-pedi- 

 celed, 3.5-5 mm., rarely but 3 or as much as 6 mm. long, 1.2-1.5 mm. wide, elliptic-ovate, 

 acuminate, strongly nerved; first glume clasping, two thirds to three fourths the length of the 

 spikelet, rarely equaling the sterile lemma, acuminate to cuspidate, 5-nerved; second glume 

 longer than the sterile lemma, both much exceeding the fruit, 5-7-nerved; fruit narrowly ovate, 

 the margins of the lemma inr oiled only at base. 



Type locality: Virginia. 



Distribution: Maine to Montana, south to Florida and Arizona, and through Mexico to 

 northern South America. 



Illustrations: Trim Ic. pi. 228; Vasey, Agr. Grasses U. S. pi. 12; de. 2. pi. 16; Bull Term. 

 Exp. Sta. 7: pi. 9, f. 35; Bull. U. S. Dep. Agr. Agrost. 7:/. 54; 14:/. 68; Contr. U. S. Nat. Herb. 

 15: /. 79; Britt. & Brown, 111. Fl./. 270; ed. 2./. 323. 



Panicum virgatum cubense Griseb. Cat. PI. Cub. 233. 1866. Panicum virgatum obtusum Wood, 

 Bot. &Fl.ed. 1871. 392. 1871. Panicum virgatumbreviramosumNash, Butt. Torrey Club 23: 150. 

 1896. Differing in the usually more slender culms, solitary or few in a clump, the usually narrow 

 panicles with ascending branches, and the smaller spikelets, 2.8-3.2 mm. long, the first glume usually 

 about half the length of the spikelet, acute but usually not acuminate-pointed, the second glume 

 and sterile lemma about equal and but slightly exceeding the fruit, the latter about 2 mm. long. 

 Atlantic Coastal Plain from Connecticut to Florida; also in Bermuda and Cuba. Originally 

 described from Cuba. Illustration: Contr. U. S. Nat. Herb. IS: /. 81. 



47. Panicum ichnanthoides Fourn. Mex. PL Gram. 30. 1886. 



Panicum Buchingeri Fourn. Mex. PI. Gram. 30. 1886. 



Plants in large clumps with knotted crowns, without creeping rootstocks; culms 1.5-2 

 m. high, erect or decumbent at the base, smooth, firm and hard, more or less glaucous about 

 the nodes; leaf-sheaths shorter than the internodes, pubescent on the overlapping margin 

 toward the apex, otherwise glabrous; ligule about 3 mm. long, membranaceous-ciliate ; blades 

 elongate, mostly 8-15 mm. wide, flat except at the narrowed and usually inrolled base, scabrous 

 on the margins, villous on the upper surface near the base, otherwise glabrous; panicles 20-40 

 cm. long, one fourth to one third as wide, the long slender branches ascending; spikelets 3.5-4.2 

 mm. long, about 1.5 mm. wide, similar to those of P. virgatum. 



Type locality: Orizaba, Vera Cruz. 

 Distribution : Southern Mexico to Nicaragua. 

 Illustration: Contr. U. S. Nat. Herb. 17:/. 55. 



48. Panicum altum Hitchc. & Chase, Contr. U. S. Nat. Herb. 17: 



488. 1915. 



Plants perennial, in tangled masses, the culms decumbent and straggling at base, stout, 

 reed-like, as much as 6 mm. in diameter, ascending to a height of 2-4 meters, smooth and 

 glaucous, simple or with extravaginal mostly erect sterile branches from the swollen nodes; 

 leaf-sheaths smooth; ligule a short membrane less than 1 mm. long, the ciliate fringe once or 

 twice as long; blades flat, firm, not greatly elongate, mostly 30-45 cm. long, 8-15 mm. wide, 

 smooth except the scabrous margins; pancles rather more densely flowered than in P. zirgatum, 

 20-30 cm. long, narrowly ovoid in outline, open, the slender scabrous branches ascending and 

 spreading, fascicled, some naked at the base with short branchlets intermixed; spikelets rather 

 short-pediceled, 3.2-4 mm. long, about 1.2 mm. wide, turgid, glabrous, the glumes and sterile 

 lemma strongly nerved, pointed, somewhat keeled, usually widely gaping, the first glume about 

 two thirds the length of the spikelet, the second glume and sterile lemma exceeding the fruit, 

 subequal; fruit 2-2.2 mm. long, 1 mm. wide, elliptic. 



Type locality: Point Cham6, Panama. 

 Distribution: Costa Rica to Trinidad. 

 Illustration: Contr. U. S. Nat. Herb. 17:/. 57. 



