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. urvilleanum. 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 lemma 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. 

 California: San Jacinto, S. 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. 



