HITCHCOCK AND CHASE-—TROPICAL NORTH 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; panicles dark purple.. 58. P. cupreum. 
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 ......5.-....----- 22 ee eee ee eee ee 57. P. hians. 
Panicle branches branchlet-bearing throughout their 
length or nearly so. .........--------- 2... 56. P. exiguiflorum. 
Panicle branches subracemose, the spikelets secund; blades 
at least 5 mm. wide; enlarged sterile palea not con- 
spicuous. 
Blades narrowed toward the base..........-..-.. ceeeeee 54. P. laxum. 
Blades cordate or truncate at base. 
‘Spikelets 2 mm. long; panicle branches erect or 
nearly SO... .....--2 2-22 e eee eee eee eee eee 55. P. stevensianum, 
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. ...-.--- 22. eee ee eee ee eee eee 53. P. boliviense. 
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........---.------ 51. P. milleflorum. 
Culms not over 1 meter long; panicles 5 to 
15 cm. long.....-..-.-------------- 52. P. pilosum. 
49. Panicum longum Hitche. & Chase. ij f Seettepienes 
Panicum longum Hitche. & Chase, Contr. 
U.S. Nat. Herb. 15: 111. 1910. 
DISTRIBUTION. 
Swamps, State of Veracruz. The only 
collections known are from near Jalapa, 
Pringle 8195 (the type) and Schiede & Deppe 
674 (Halle Herb.). 
Fig. 68.—Distribution of P. longum. 
50. Panicum polygonatum Schrad. 
Panicum polygonatum 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: Cérdoba, Bourgeau 1662 in part. 
GuaTEMALA: Sepacuité, Collins & Goll 08, Cook & Griggs 530. Cubilquitz, 
Tiirckheim 7797, 8795. Puerto Barrios, Kellerman 5114. 
Honpuras: San Pedro Sula, Thieme 781, 5578, 5587 in part, 
