NOTES ON AMERICAN WILLOWS 
I. THE SPECIES RELATED TO SALIX ARCTICA PALL. 
CAMILLO SCHNEIDER 
The more I advance in the study of American willows the more 
I realize that every species and form needs thorough investigation, 
and that even the most common and apparently best known species 
are far from being well understood in their variation and relation- 
ship to other forms. It will take two years more before I shall be 
sufficiently acquainted with all the American species hitherto 
described and preserved in the leading herbaria of this country to 
undertake their final arrangement in a monograph. At the advice 
of Professor SARGENT, therefore, I shall prepare, in the course of 
my studies, a series' of papers dealing with those species and forms 
which I have had an‘opportunity to investigate as thoroughly as 
can be done with herbarium material only. In November 1917 I 
commenced an investigation of the willows treated by RYDBERG in 
his paper entitled ‘‘Caespitose willows of Arctic America and the 
Rocky Mountains” (Bull. N.Y. Bot. Gard. 1:257. 1899). I re- 
ceived from the New York Botanical Garden and from the Her- 
barium of the Geological Survey of Canada at Ottawa the 
material that RypDBERG had before him. Besides this I had at 
my disposal the splendid collections of the Gray Herbarium, the 
Missouri Botanical Garden, and of course of the Arnold Arbore- 
tum. Furthermore, I was able to see the Labrador material of the 
Bebb Herbarium, now in the Herbarium of the Field Museum at 
Chicago, and also very interesting collections made in Labrador, 
Greenland, and Alaska from the Herbarium of Cornell University. 
I take this opportunity to offer my best thanks to the gentlemen in 
charge of all these herbaria. Unfortunately I have not been able 
to look over the rich collections of the U.S. National Herbarium at 
Washington. 
It would have been of the greatest advantage if I could have 
seen the material collected by LuNpstROM and used in his ‘‘Kritische 
* For my first paper see Bor. Gaz. 65:1-41. 1918. 
ex7] , [Botanical Gazette, vol. 66 
