1918] SCHNEIDER—AMERICAN WILLOWS 335 
S. glaucops. In his Fl. Rocky Mts. 190. 1917, he says the same 
and adds that the leaves are 2-3 cm. long in the first, while 
they measure 3-6 cm. in length in the second species. The 
largest leaves of S. pseudolapponum I have seen measured up to 
5-5:1.8 cm., but usually they are not longer than 4-4.5 cm., 
and from about 1.5 to 2.2 cm. wide. RYDBERG apparently refers 
to his glaucops some forms which I do not regard as belonging to it, 
giving as the range ‘Alta —N.M.—Utah—Calif—Yukon,”’ while 
he restricts S. pseudolapponum to Colorado. The type of this 
species (Baker, Earle, and Tracy, no. 300%, male) came from Mount 
Hesperus in the La Plata Mountains in southwestern Colorado, and 
represents a young flowering stage which naturally looks rather 
different from a fully developed specimen with old fruits. After 
having compared an extensive series of well collected specimens, I 
fail to see how it is possible to separate specifically this southern 
- Colorado plant from the other forms in Colorado, where the species 
seems to have its headquarters, but the typical S. pseudolapponum 
may represent a dwarfed more alpine form of the so-called 
S. glaucops, which, therefore, should be distinguished as a new 
variety of S. pseudolapponum. There are several forms which 
otherwise seem to be identical but do not have stomata in the upper 
leaf epidermis, with which the typical S. pseudolapponum is always 
provided, differing in this respect from S. brachycarpa (see later). 
So far as I can judge by the copious material before me, these two 
- Species seem to hybridize rather freely, and I cannot explain certain 
forms in any other way. We need, however, a much more careful 
study of these forms in the field to decide the question whether 
these hybrids are common. ' From New Mexico | know S. pseudo- 
lapponum only in a somewhat uncertain sterile form from Taos 
County, Costilla Valley (leg. E. O. Wooton, September 4, 1914), 
and from Wyoming I saw no specimen but Nelson’s no. 7831 from 
the Medicine Bow Mountains in Albany County. From farther 
northward I saw specimens from Teton County, Montana (leg. 
C. S. Sargent in 1883), and from Alberta, Sulphur Mountain, near 
Banff (leg. A. Rehder, August 8, 1904). Specimens from Lake 
County, Utah, need further observation, and I have seen nothing 
from Nevada, California, Oregon, or Washington which I can refer 
