SMITHSONIAN IN ST IT! ["ION 



UNITED STATES N A NONAL MUSI I M 



CONTRIBUTIONS 



1 ROM THE 



United States National Herbarium 



Volumi-: X. Part 2 



BE GENUS PTELEA 1\ THE WESTERN AND SOUTHWESTERN 

 UNITED STATES AND MEXICO 



By EDWARD L. GREENE 



• D 



WASHINGT* >N 



G< IVERNMEN I PRINTING I >FFICE 

 [Q0 6 



