10 BULLETIN 1113, U'. S. DEPARTMENT OF AGRICULTTJEE. 
cottonwood {P. deltoules). It has not yet been tested throughout 
the Great Plains region as a shelter-belt tree. 
Narrow-leaved cottonwood. — The narrow-leaved cottonwood (Pop- 
ulus angustifolm) prefers moister situations than its related species, 
and clings closely to the rh T er and creek margins and low flood lands. 
It is a Rocky Mountain species, having a range much more restricted 
than the acute-leaved poplar. It has been planted as a street tree 
within its range, but it makes a poor showing for this purpose. 
Its usefulness for shelter-belt planting is doubtful. 
Diamond irflloic. — The diamond willow (Salix mackenzieana) is 
found generally throughout the Great Plains area. It follows the 
river and creek bottoms to the foothills of the Rocky Mountains. It 
is a tree of some economic importance as a source of fence posts. It 
has been planted in shelter belts on the prairie with only fair suc- 
cess. 
Bur oak. — The bur oak (Quercus macrocarpd) is found as far 
west as the Black Hills and in the Bad Lands of western North 
Dakota, southeastern Montana, and northeastern Wyoming. It 
grows on the drier sites along stream banks and old flood plains, 
occasionally venturing to the lower prairie levels. It does not grow 
to a great size, though specimens are found of apparent great age. It 
has riot been considered a practical tree for transplanting to shelter- 
belt sites. 
Chokecherry. — The chokecherry (Prunus virginiana) ranges 
throughout the entire Great Plains region along the river courses 
and up the dry coulees to the prairie levels, where it is often found 
associated with the green ash. It is well adapted for shelter-belt 
planting, doing well in all situations except very sandy or low wet 
soils. 
Buffalo terry. — The buffalo berry, or bullberry (Shepherdia 
aryentea), is closely associated with the chokecherry in range and 
adaptability for shelter-belt planting. It is more suited to the sandy 
types of soil, but does not favor low wet situations. 
CONIFEROUS OR EVERGREEN SPECIES NATIVE TO THE REGION. 
Black Hills spnice. — The Black Hills spruce (Picea canadensis) , 
a form of white spruce found in the Black Hills of South Dakota, 
has certain characteristics which distinguish it from the common 
white spruce of northern Minnesota and Canada. It is not exacting 
as to soil types, but prefers the drier locations. It is one of the best 
evergreens for shelter-belt planting in the northern Great Plains. 
Figure 5 shows spruce on the east side of the deciduous shelter belt 
at the Northern Great Plains Field Station, Mandan. X. Dak. The 
three rows from left to right are blue spruce, white spruce, and Black 
Hills spruce. The relatively greater size of the Black Hills spruce 
