1918] SCHNEIDER—AMERICAN WILLOWS 321 
S. glauca from Northern Europe. According to the leading Euro- 
pean salicologists S. glauca is rather variable, but I fail to find a 
good arrangement of the different variations already known from 
Europe and Northern Asia in the existing literature. It is impos- 
sible to judge the American forms correctly without having a clear 
understanding of the Asiatic forms already described, because it is 
to be expected that the forms from Eastern Asia will have the closest 
affinity with the American forms. 
No mention is made of S. glauca by Pursu (1814) or MicHaux 
(1820), or even by HooKER (1839). It was ANDERSSON who in 
1858 first mentioned S. glauca as occurring “in provinciis septen- 
trionalibus et arcticis Americae borealis.”’ He further said: 
Haec species . . . . in arcticis regionibus Americae habitu externo vix 
nostrae similis exstat. Specimina tamen a Seemann in parte occidentali et a 
Lyall in Disco Island lecta, nec non e “Rocky Mountains” reportata cum 
nostris tamen ita congruunt, ut de identitate non dubitare liceat. Folia nunc 
utrinque molliter villosa et incana, nunc denudata subviridia, amenta semper 
foliato-pedunculata, capsulae brevius pedicellatae. Huic certissime ut forma 
tantum associanda—villosa. S. villosa (D. Don) Hook. l.c. p. 144, no. 3. 
This S. villosa Barratt apud HooKER has to be ascertained before 
anything else can be done to determine which forms may be refer- 
able to S. glauca. Hooker (FI. Bor.-Am. 2:145. 1839) said: “that 
‘Dr. Barratt considers it to be the same as S. villosa of D. Don, 
in Pursh, Herb. Canad.’”’ I have never seen specimens from a 
“Herb. Canad.” of Pursu, nor do I know whether Pursu ever dis- 
tributed such a collection.2, Neither he nor D. Don published a 
S. villosa; there are, however, two species bearing this name, one 
of SCHLEICHER (Cat. Pl. Helv. ed. 3.26. 1815) which is a nomen 
nudum and was probably first mentioned in the first edition of the 
Catalogue in 1809; the other of Forses (Salict. Wob. 183. pl. 92. 
1829) representing a sterile specimen of unknown origin. Thus the 
2There is, however, a specimen, consisting of 3 leaves only, in herb. N. labeled 
“Salix Micha D. Don, in Pursh’s Canadian Herb. (collected in Lord Selkirk’s 
Exped. from Mr. Lambert’s Herb.).” Down did not publish a species S. leucodendron, 
and I am not yet sure to which species these 3 leaves belong. PuRsx’s herba- 
in possession of LAMBERT (see Gard. Chron. 1842, p. 439), but Purs# him- 
self did not collect in Canada at all (see HarsHperceEr, Bot. Philad. 115. 1899). 
I have not been able to get any information on ‘‘Lord Selkirk’s Exped.” 
