SHELTER-BELT DEMONSTRATIONS ON THE GREAT PLAINS. 



9 



northern tree, ranging nearly to the Arctic Circle, it may not adapt 

 itself to the hot summer temperatures of the Great Plains. 



Aspen. — The aspen {Populus ti^emuloides) is scattered sparsely 

 over portions of the Plains region. It is found in the river valleys, 

 on the north sides of small mountain groups, on occasional steep 

 bluffs, and in the sand-dune area near the Mouse River in North 

 Dakota. It is also found on the borders of lakes in the Coteau du 

 Missouri and in depressions or coulees in the prairie where under- 

 ground springs exist. It has been used in some instances for farm 

 plantings, and makes a dense growth, though of no great size. 



Northwest poplar. — The northwest poplar {Populus sp.) was given 

 its name by one of the commercial nurseries in North Dakota. It 

 was discovered in the northern part of that State, and is supposed 



Fig. 4. — Northwest poplar (row at left) in its fourth year of growth in a shelter belt in 



Sheridan County. N. Dak. 



to be a natural hybrid presumably between the balsam poplar and 

 the aspen. Whatever its origin, it is the most promising poplar 

 for shelter-belt planting in the Great Plains area that has yet 

 been tested. It is perfectly hardy, seems to grow on all types of 

 soil, and is superior to the cottonwood on the drier locations. Figure 

 4 shows the northwest poplar in its fourth year of growth in a 

 shelter belt in Sheridan County, N. Dak. 



Acute-leaved cottonwood. — The acute-leaved cottonwood {Populus 

 acuminata) is native to the foothills of the Rocky Mountains. It is 

 found along the banks of streams in Montana as far east as the 

 Powder River and in Wyoming to the Black Hills in South Dakota. 

 This tree has been used for street planting in cities of the Rocky 

 Mountain region, and is superior for that purpose to the common 

 3607°— 22 2 



