OP ARTS AND SCIENCES. 51 



to publish his views of these plants, aftei* having studied them in sev- 

 eral of their natural districts, and in the largest collections. 



For two years I occupied myself with the Willows in various regions 

 of Lapland. I afterwards collected them in the Riesengebirge (Silesia), 

 in Switzerland, and in many parts of the Continent, and in England. I 

 have consulted the herbaria, as well as the botanical gardens, of Paris, 

 Berlin, and Vienna ; also the herbaria of M. De CandoUe and of Sir 

 W. Hooker, the latter the largest now existing, and especially rich on 

 plants from North America. For many years I have wished to pub- 

 lish some general remarks upon this genus ; and M. De Candolle has 

 lately honored me with a request to elaborate it for his celebrated 

 Prodromus. 



But in arranging for such a work my annotations upon the Northern 

 species, I could but know how imperfect is our knowledge of the North 

 American forms. As the Willows especially belong to cold regions, 

 why should they not be as numerous in America as in Europe or Asia ? 

 As they are with us so extremely subject to variations and to hybridi- 

 zations (a fact now generally acknowledged), must it not be the same 

 in the New World ? To answer these and similar questions, our ma- 

 terials in Europe are not sufficient, and all determinations founded 

 upon them alone must be imperfect, and liable to frequent mistakes. 

 In this dioecious genus it is very important to be sure that the speci- 

 mens, both of leaves and flowers, belong to the same species, and that 

 the foliage, flowers, and fruit should be taken from the very same 

 shrub. But in herbaria the specimens — gathered by travellers who 

 generally care little for Willows — often are so imperfect, confused, and 

 miserable, that they only serve to make the study more difficult and 

 uncertain. 



Looking into the American Floras, published by various authors 

 since the time of Michaux, we find that the indigenous Salices of 

 America (with the exception of a few of the most arctic) all have names 

 totally differing from the European species. Now this was hardly to 

 be expected, when the well-known fact is considered that the vegetation 

 of a large part of the Northern regions is, I dare not say quite identi- 

 cal, but very uniform or homogeneous, all round the world. Hence, 

 although the indigenous Willows in America generally are considered 

 different from those in the Old World, we should look for a greater 

 resemblance than has yet been recognized, not only in the higher arctic 



