HITCHCOCK AND CHASE—NORTH AMERICAN PANICUM. 133 
mm. wide, and as much as 4 mm. thick, ovate, densely silvery to tawny villous, 
strongly nerved but the nerves obscured by the pubescence; first glume clasping, two- 
thirds to nearly as long as the spikelet, sparsely villous or glabrescent toward the 
Fig. 127.—P. urvilleanwm, From type specimen. 
acuminate apex; second glume slightly longer and more pointed than the sterile 
lemma, both exceeding the fruit, the lemma inclosing a villous palea of equal length 
and a staminate flower; fruit 4.2 to 4.5 mm. long, about 1.6 mm. wide, the margins of 
the Jemma clothed with long white hairs, otherwise smooth and shining. 
DISTRIBUTION. 
Sandy deserts, Arizona and southern California south to Argentina. 
Arizona: Without locality, Lemmon in 1884. 
CauirorNIA: San Jacinto, 8. B. & 
W. F. Parish 887 in 1882; Agua 
Caliente, S. B. & W.F. Parish 
887 in 1881; Barstow, Chase 
5766, Tracy 434; Hesperia, 
Abrams 2164; Colorado Desert, 
Chase 5519, Parry & Lemmon 
400 (Hitchcock Herb.), Wilder 
1082. 
ARGENTINA: Rio Negro, Wilkes S. 
Pac. Expl. Exped. in 1838- 
1842. 
CHILE: Gillies (Gray Herb.). Fig. 128.—Distribution of P. urvilleanum. 
UNGROUPED SPECIES OF TRUE PANICUM. 
» The following tropical species do not fall into any of the foregoing natural groups 
nor, with the exception of Panicum rudgei and P. rotundum, which are allied 
species, do they form such groups among themselves. The Mexican and Central 
American species are as yet not so well understood as those of the United States, 
and further study is necessary before our knowledge of the species of the former 
regions shall be as detailed as that of the species occurring north of the Mexican 
boundary. This study awaits additional material and extended field work in Mexico 
and Central America. 
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