TREE SPECIES. | 35 
than in Kansas, but there, too, the predominating species is the 
almondleaf, which is common throughout the State. The black wil- 
low, when true to type, has much the narrower leaf, but the general 
appearance and habits of, the two species are the same. 
The Bebb willow (Salix bebbiana) comes into western Nebraska, 
and is most abundant in Sioux County. The largest trees attain a 
diameter of 8 inches and a height of more than 30 feet. 
The sand-bar willow (Salix fluviatilis) is not usually considered a 
tree, though its manner of growth, and occasionally its size, entitle it 
to be classed as one. It is common along sandy streams, but is less 
plentiful or quite lacking on streams that have a heavy soil. ‘The 
Platte and the Arkansas are particularly adapted to it. The value 
of the sand-bar willow les in the fact that its wide-spreading roots, 
which send up.a new shoot every few inches, make it the most effec- 
tive agent-in holding sand bars and preparing the way for more 
permanent species. | 
ASPEN. 
Considerable aspen (Populus tremuloides) is found in a few Sioux 
County canyons. It is particularly abundant in Squaw Canyon, not 
far from the Wyoming line, where the larger trees attain a diameter 
of 8 inches and a height of 40 feet. The wood is valuable for fuel 
only. 
HAIRY BALM OF GILEAD. 
This tree (Populus balsamifera candicans), which Doctor Bessey 
describes in his report on the native trees and shrubs of Nebraska as 
“a tree with heart-shaped leaves, which are whitish underneath, 
found in Sioux County,” is so much like the common cottonwood that 
it is not likely to be distinguished from it by the ordinary observer. 
COTTON WOODS. 
The common cottonwood (Populus deltoides) is the largest native 
tree of Kansas and Nebraska. It is the typical species of the Arkan- 
sas and the Platte, and is at home on every sandy stream (see PI. 
IV). Trees of 5 feet or more in diameter are occasionally found, and 
those of 4+ feet are not uncommon. 
The lanceleaf cottonwood (Populus acuminata) and narrowleaf 
cottonwood (Populus angustifolia) have a wide distribution in 
western Nebraska. They are found in many canyons in Scotts Bluff 
and Sioux counties, growing in company with the common species, 
from which they differ only in the shape of the leaves. The narrow- 
leaf cottonwood has a long, tapering, willowlike leaf, while that of 
the lanceleaf has a shape midway between it and the common one. 
