HITCHCOCK AND CHASE TROPICAL NORTH AMERICAN PANICUM. 529 



DISTRIBUTION. 



Swamps, growing in the water, south- 

 ern Mexico to Panama. 



Tabasco : Between San Juan Bau- 

 tista and San Sebastiiin, 

 Rovirosa 625. 

 Guatemala: Puerto Barrios, Hitch- 

 cock 9153. 

 Panama: Frijoles, Hitchcock 8388. 





\ 







-i 





"si 



Fig. 142. — Distribution of P. stagnatile. 



113. Panicum grande sp. nov. 



Plants perennial, gregarious, producing extensively creeping or floating leafy 

 stolons about 5 mm. thick; culms 1.5 to 2 meters or more high, erect from a long decum- 

 bent base with papery sheaths and tufts of fibrous roots, 1 to 2 cm. thick, simple or 

 sparingly branching, succulent, the nodes densely appressed-hirsute; sheaths over- 

 lapping except toward the summit, glabrous, the junction with the blade in drying 

 presenting a darkened triangle on each side; ligule membranaceous, 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; panicle as much as 60 cm. long and 40 cm. wide, the axis 

 and branches strongly several-angled, scaberulous, the promi- 

 nent pulvilli 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 to 

 2 mm. long; spikelets 2.5 mm. long, 0.9 mm. wide, nearly 

 terete, pointed, glabrous; first glume slightly over half the 

 length of the spikelet, the 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 indurate but the lemma 

 margins flat. 



Type in U. S. National Herbarium, nos. 693329, 693330, 693331 (parts of the same 

 indiAndual), collected in the water of a swamp along the margin of Gatun Lake, Canal 

 Zone, Panama, December 15, 1911, by A. S. Hitchcock (no. 9178). 



This species grows in large masses in swamps, flowering in December. The broad 

 blades give a lily-like aspect to the plants earlier in the season. In Gatun Lake, 

 Panama, plants were found growing in 10 feet of water. 



DoelP describes this si:)ecies imder the name Panicum multifiorum Poir.,^ but the 

 latter name applies to a different species.^ Panicum grande is allied to the South 

 American P. grumosum Nees, P. rivulare Trin., and P. prionitis Nees, from all of which 

 it differs in its aquatic habit and open panicle and in the more indurate fertile lemma 

 and palea; from P. rivulare and P. prionitis in the equal second glume and fertile 

 lemma. 



1 Mart.Fl. Bras. 2h 215. 1877. 



2 Encycl. 4: 282. 1816. 



' See Contr. U. S. Nat. Herb. 15: 48. 1910. 



Fig. 143.— p. grande. From 

 type specimen. ■ 



82472°— 15- 



