HITCHCOCK AND CHASE—TROPICAL NORTH AMERICAN PANICUM. 473 
DICHOTOMIFLORA. 
Three species of this group, Panicum aquaticum, P. sucosum, and P. elephantipes, 
are found to be perennial. 
Plants annual. 
Panicles narrow, less than 1 cm. wide..............-.-. 14. P. vaseyanum. 
Panicles open, the branches ascending or spreading. 
Sheaths glabrous........---22---- 22-22 - eee ee ee eeee 15. P. dichotomiflorum. 
Sheaths papillose-hispid...............------------ 16. P. bartowense. 
Plants perennial. 
Fruit not acuminate; panicles rarely over 18 cm, long... 17. P. aquaticum. 
Fruit acuminate; panicles as much as 40 cm. long, rarely 
less than 20 cm.; culms succulent. 
Spikelets about 3.5 mm. long; fruit abruptly acumi- 
112) 18. P. sucosum. 
Spikelets 4 to 5 mm. long; fruit long-acuminate; 
culms very succulent.........--..-.-.0---05- 19. P. elephantipes. 
14. Panicum vaseyanum Scribn. 
Panicum vaseyanum Scribn.; Beal, Grasses N. Amer. 2: 140. 1896; Contr. U. 8. 
Nat. Herb. 15: 47. 1910. ’ 
DISTRIBUTION. tad 
Moist open ground, around ponds and de- }. p 
pressions in prairies, northern Mexico, The K 
type specimen from Chihuahua. — 
Curavanua: Base of Sierra Madre, 
Pringle 1415. Miiiaca, Hitchcock o> 
7757. 
AGUASCALIENTES: Aguascalientes, Mitch- 
cock 7491, Amer. Gr. Nat. Herb. 15. 
Jauisco: Guadalajara, Hitchcock 7315. Fig. 25.—Distribution of P. vaseyanum. 
15. Panicum dichotomiflorum Michx. 
Panicum dichotomiflorum Michx. F1. Bor. Amer. 1: 48. 1803; Contr. U. 8. Nat. Herb. 
15: 48. 1910. 
The South American Panicum chloroticum Nees, included in the Reyision in P. 
dichotomiflorum, is a distinct species, or possibly a subspecies. It is not known from 
north of Brazil. 
DISTRIBUTION. 
SOG uk \" S Moist ground along streams and a 
© ge phy weed in waste places and in cultivated 
ch AS If soil, Maine to Florida and California 
Were ee -«. / (rare in the West), and in the West 
we, ‘0 re * ' 
os aN a = eal ‘, Indies and Panama. The type speci- 
Sear if . ‘geé | men from the Alleghenies. 
Panama: Near Chepo, Pittier 4614. 
. Gatun, Hitchcock 7977. 
Bermupa: Hamilton, Millspaugh 
126. 
Banamas: Hog Island, Eggers 4405, 4512. Watlings, Geogr. Soc. Baltimore 489. 
Nassau, Curtiss 177. Cat Cay, Brace 3742. 
Fig. 26.—Distribution of P. dichotomiflorum. 
