48 
that they are two distinct species, or, at least, two varieties, let us 
see which has the right to the name of Populus angustifolia, James. 
The original description by James I have not seen, but I 
must suppose that both Dr. Watson and Nuttall knew James’ tree, 
and have described the same. Dr. Watson writes in his Revision 
of the North American Cottonwoods: 
« P. angustifolia, James. Leaves not white beneath, rhombic- 
ovate to narrowly lanceolate, mostly cuneate at the base, often 
small, petioles one-half inch long or less (rarely one inch), etc.” 
In King’s Report, the description of Populus balsamifera, var. 
angustifolia, contains among other characters: 
« . , . leaves ovate-lanceolate, attenuate at the base, acute, 
glabrous, crenate-serrate. Leaves varying much between the ordi- 
nary growth (2’-3’ long by 8’—-12” wide, acute and often sub- 
rhomboidal) and that of younger shoots where they may be 6’—8’ 
long and 3’ or more broad, and often cordate at base, always with 
long acumination.” 
Nuttall, in Silva Americana, gives about the same description, 
and adds: 
“The footstalks of the leaves or petioles are about three-fourths 
toaninchin length. The nerves are all faint beneath and pinnate, 
with no appearance of being 3-nerved at the base; the number of 
these nerves or lateral vessels is twelve to fifteen on a side, at 
least double the number they are in the Balsam Poplar.” 
These descriptions can only apply to the form we are used to 
call P. angustifolia, James. All specimens thereof found at present 
in the Herbarium of the University of Nebraska, agree in 
that the petioles are short, from ¥ to I inch long, and the lateral 
nerves are, at least in the larger leaves, about 10-15 on each side. 
(See Plate CXL.). In the specimens of my No. 372, from Carter 
Canon, and of the same tree collected, this year, at Hot Springs, 
S. D., the petioles are from 1-2 inches or even more, and the 
lateral nerves seldom more than 8. . 
As it is remarked by Dr. Watson, the leaves of the Black 
Cottonwood vary considerably, especially on young shoots. All 
specimens I have used for comparison are taken, however, from 
trees over 20 feet high. The first leaves from the bud are generally 
more or less ovate, I-2% inches long. These are followed by - 
