1918] SCHNEIDER—AMERICAN WILLOWS — 121 
I have seen but one leaf of the type specimen of Pattas. It 
does not possess stomata in the epidermis of the upper surface, a 
character upon which I am inclined to lay considerable stress. It 
is true that by A. and E.-C. Camus (Class. Saules Europe 2:55. 
1905) S. arctica is said to possess ‘“‘stomates ... assez nombreux” 
in the upper leaf epidermis, but judging by their synonymy 
these authors include under S. arctica so many widely different 
forms that they probably did not examine a true arctica at all. 
So far as I can see, this species is represented in the New World 
only in Alaska, the Yukon Territory, and the adjacent part of the 
northwest corner of British Columbia, and in the apparently well 
marked var. subcordata in southern British Columbia. I am not 
yet quite sure how far the range of S. arctica extends toward the 
east, but it seems not to cross 130° W. longitude except in the var. 
subcordata, of which the geographical distribution is not yet fully 
known. The specimen collected by BELL on Nottingham Island, 
Hudson Strait (no. 24623 O.? olim 18825), which is cited by RYDBERG 
under SS. arctica Pall., belongs certainly to S. anglorum. 
There seems to be no great difficulty in distinguishing typical 
forms of S. arctica from those of S. anglorum if one has well devel- 
oped specimens. Very often, however, it is necessary to deal with 
mere fragments, and in this case the best character seems to be 
furnished by the presence or absence of stomata in the upper leaf 
surface. While they are entirely lacking in what I take for typical 
S. arctica, they are more or less numerous in all the specimens I 
have seen of S. anglorum. Generally, S. arctica is a much more 
robust plant with larger leaves and catkins and thicker branchlets, 
but when we compare the shape and pubescence of the leaves and 
the different characters of the flowers and fruits it is rather difficult 
to express in words those signs that the eye can more or less easily 
perceive. The best description of the American form of S. arctica 
is given by Covitte in his excellent study of the “Willows of 
Alaska”’ (1901), to which is added a good plate. I shall say some- 
thing more about the differences between S. arctica and S. anglorum 
= citing herbarium specimens I use the same abbreviations as in my first paper; 
- Gaz. 65:9. 1918. There are to be added the following: C., Herb. Field 
Csliens Miscuin: Cor., Herb. Cornell University; O., Herb. Geol. Surv. Canada. 
