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NEW YORi 

 *^TANlCAl 



PREFACE. 



Of the Synoptical Floka of North America Dr. Gray published, 

 in 1878, Volume II. Part 1, comprising the gamopetalous orders after 

 the CompositcG, and following rather closely, in the sequence and limita- 

 tion of orders, Bentham & Hooker's Genera Plantarum. The object 

 in thus beginning with the second portion of the work was to monograph 

 first such orders as had not been treated in Torrey & Gray's Flora of 

 North America. This earlier work, published between 1838 and 1843, 

 included the polypetalous orders of North America and the Gamopetalce 

 through the Compositce. In planning the Synoptical Flora, Dr. Gray 

 left the orders thus treated to form the subject matter of Volume I. In 

 1884, he published Part 2 of tliis first volume, inclucUng the Gamopetalce 

 from the Caprifoliacece tln:ough the Composite^. In 1886, the two por- 

 tions, thus published, were revised and amplified by Dr. Gray, and 

 reissued by the Smithsonian Institution. 



In his last years Dr. 'Gray was engaged in monographing the earlier 

 polypetalous orders for Volume I. Part 1. In tliis work he had finished 

 at the time of his death most of the orders to, but not including, the 

 Leguminosce. The treatment of several large groups, however, such as 

 the Cruciferce^ Garyophyllacece, Hypericacece, Ehamnacece^ &c., had for 

 various reasons been deferred. After Dr. Gray's death the work was 

 continued by Dr. Sereno Watson, who prepared eleven genera of the 

 Gruciferce, including several of the largest and most difficult of the order. 

 After the death of Dr. Watson, in 1892, the work was intrusted to the 

 present editor. 



The time which has necessarily elapsed since the inception of the work 

 by Dr. Gray and the very considerable botanical activity tlnoughout our 



HAY- t1S67 



