HITCHCOCK AND CHASE TROPICAL FORTH AMERICAN PANICUM. 493 



Spikelets expanded at maturity by the enlarged sterile palea, 

 usually blunt. 

 Panicle branches not racemose; blades scarcely wider than 

 their sheaths; sterile palea conspicuously enlarged. 

 Spikelets 3 mm. long, congested; panicle^ajkpftrple.. 

 Spikelets not over 2.4 mm. long; panicles green or pale. 

 Panicle branches spikelet-bearing or branchlet 

 bearing along the upper half or toward the 



ends only 57 



Panicle branches branchlet-bearing throughout their 



length or nearly so 56 



Panicle branches subracemose, the spikelets secund; blades 

 at least 5 mm. wide; enlarged sterile palea not con- 

 spicuous. 



Blades narrowed toward the base 54 



Blades cordate or truncate at base. 



Spikelets 2 mm. long; panicle branches erect or 



nearly so 55, 



Spikelets not over 1.6 mm. long, usually less; panicle 

 branches spreading or ascending. 

 Panicles one-third to half as wide as long; spike- 

 lets not conspicuously secund, somewhat 

 irregularly disposed; blades cordate- 

 clasping 53 



Panicles rarely one-fourth as wide as long; spike- 

 lets conspicuously secund and regularly 

 disposed. 

 Culms as much as 2 meters long; panicles 



25 to 30 cm. long 



Culms not over 1 meter long; i^anicles 5 to 

 15 cm. long 



58. P. cupreum. 



P. Mans. 



P. exiguiflorum. 



P. laxum. 



P. stevensianum. 



51. 



P. holiviense. 



P. fnilUflorum. 

 P. pilosum. 



49. Panictrm long-um Hitchc. & Chase. 



Panicum longum Hitchc. & Chase, Contr. 

 U. S. Nat. Herb. 15: 111. 1910. 



DISTRIBUTION. 



Swampf, State of Veracruz. The only 

 collections known are from near Jalapa, 

 Pringle 8195 (the type) and Schiede <fe Deppe 

 674 (Haile Herb.). 



Fig. 68.— Distribution of P. longum. 



60. Panicum polygonatum Schrad. 



Panicum polygonalum Schrad. in Schult. Mant. 2: 256. 1824; Contr. U. S. Nat. 

 Herb. 15: 112. 1910. 



DISTRIBUTION. 



Swamps and moist soil, Mexico to Paraguay. The type specimen from Brazil. 

 Veracruz: Cordoba, BoMJ-greaji 1662 in part. --<J i'/-- •/»''. -^ 



Guatemala: Sepacuit^-, Collins & Goll 08, Cook & Griggs 530. Cubilquitz, 



Tilrclheim 7797, 8795. Puerto Barrios, Kellerman 5114. 

 Honduras: San Pedro Sula, TMeme 781, 5578, 5587 in part. 



