[Vol. 2 



574 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



monograph was suggested to me by Dr. B. L. Eobinson, 

 Curator of the Gray Herbarium, who very kindly offered to 

 place at my disposal the entire representation of this genus 

 in the Gray Herbarium, and who, moreover, willingly granted 

 me the exceptional privilege of taking abroad the North 

 American specimens, including all the types, for comparison 

 and study in European herbaria. Accordingly nearly 2,000 

 mounted specimens were taken to Berlin; and through the 

 courtesy of the authorities of the Royal Botanical Gardens 

 and Museums of Berlin every facility in that institution, 

 which is remarkably rich in Central and South American 

 plants, was accorded me and work on the task was begun 

 under the direction of Professor A. Engler. 



It was necessary first of all to acquire a detailed knowledge 

 of the general morphology of the genus Senecio as a whole, 

 and also of the closely allied genera. The results of these 

 investigations are briefly recorded in the first part of this 

 monograph, namely 'Monographic der nord- und central- 

 amerikanischen Arten der Gattung Senecio, I. Teil' which is 

 frequently referred to in the following text. This prelim- 

 inary work and the rich collections of the Gray and Berlin 

 Herbaria form, therefore, the basis for the present systematic 

 part of the monograph. 



After completing my studies in Berlin I went to London, 

 taking the Gray Herbarium specimens with me, and there 

 spent several weeks, particularly in the examination of 

 authentic and type specimens at the Kew Herbarium and in 

 the Linnean Herbarium. The opportunity at Berlin, Kew, 

 and Paris to actually compare side by side and in detail, recent 

 specimens, or series of specimens, with many of the older 

 types, some of which are more or less incomplete, has been 

 of very great advantage, and, in fact, has made it possible to 

 establish beyond doubt the identity of many of our American 

 species. 



In addition to those herbaria mentioned it also has been 

 my good fortune to study this group of plants in several 

 American institutions, notably the Herbarium of the Geo- 

 logical Survey of Canada, the United States National Her- 



