UNIVERSITY OF PENNSYLVANIA, 
Philadelphia, April 1, 1878. 
Sir: I have the honor to transmit herewith my final report “me the 
botanical collections made by the parties under your charge. 
In doing so, it is but fair to state how little of whatever merit the report 
may have is due to myself, and how much to those who have assisted in 
collecting the material, and to those who subsequently aided in naming and 
describing it. 
Dr. George Engelmann, of Saint Louis, has furnished reports upon the 
numerous orders and genera that he is our acknowledged authority upon, 
and these alone form no inconsiderable part of the whole. 
Professor Gray, of Cambridge, has throughout kindly settled all 
doubtful points of nomenclature referred to him. Without his advice and 
assistance, it would have been impossible for me to have completed the 
work. 
The same may be said of the services of Mr. Sereno Watson. He has 
also furnished the list and descriptions of the Leguminose. 
Prof. Thomas C. Porter, of Easton, has worked up the Strophulariacee, 
Polemoniaces, Labiate, Borraginacez, and Polygonacez, orders which 
together comprise a large part of the descriptive text. 
Mr. M. S. Bebb, of Fountaindale, IL, has written the account of the 
Willows, which are confessedly among the most difficult of all American 
- genera. 
Dr. George ee Botanist to the Department of Agriculture at 
Washington, D. C., has made a careful report on the Grasses collected by 
the Expedition; and Mr. William Boott, of Boston, Mass., contributes the 
paper on Carex. 
XVII 
Il BOT 
