INTRODUCTION. 29 



and well supplemented by more recent collections, especially by Professor Merritt L. 

 Fernald and his colleagues from the northeast coast; the Herbarium of the New York 

 Botanical Garden, where a splendid collection of Artemisias has been assembled, largely 

 through the efforts of Dr. P. A. Rydberg during the preparation of his account of this 

 genus for the North American Flora, and where the Torrey and other herbaria of Colum- 

 bia University are deposited; and the United States National Herbarium, where the 

 series of Alriplex is especially noteworthy, the original collection having been much 

 enlarged by Mr. Paul C. Standley during his preparation of a revision of the species for 

 the North American Flora. The Academy of Natural Sciences of Philadelphia was 

 visited with special reference to the types of Nuttall's species. Critical studies were 

 made at the E. L. Greene Herbarium, now at the University of Notre Dame, South 

 Bend, Indiana, and photographs taken of many of the type specimens. The herbarium 

 of the Missouri Botanical Garden was consulted in regard to certain types and duplicate 

 types there deposited, but time did not permit of a complete examination of all the 

 specimens in this rich collection. 



It has been found desirable in a few cases to borrow material for critical study at 

 Berkeley. Thus, a considerable collection of Chrysothamnus was received on loan from 

 the Rocky Mountain Herbarium through the courtesy of President Aven Nelson, and 

 Dr. B. L. Robinson has kindly sent specimens of Alriplex and Artemisia from the Gray 

 Herbarium of Harvard University. An authentic specimen of Artemisia domingensis 

 was contributed by the Botanical Garden and Museum of Berlin, Germany, at the 

 suggestion of Dr. I. Urban. Photographs of types have proved exceedingly useful, 

 especially when accompanied by fragments of the specimens themselves. Such photo- 

 graphs were secured in large numbers from the United States National Herbarium, the 

 New York Botanical Garden, the Gray Herbarium, and the Greene Herbarium. These 

 prints, together with the fragments which usually accompanied them, were obtained in 

 part as an exchange with the University of California, where they now form a part of 

 the botanical collection. 



Grateful acknowledgment is here made to the curators of the various herbaria men- 

 tioned above, both for the privilege of examining specimens under their care and for 

 valuable suggestions and critical opinions given during the progress of the work. In 

 this latter connection should be mentioned also the large number of botanists, foresters, 

 and others who have been consulted from time to time on certain matters with which 

 they were especially familiar. 



