8 BULLETIN 1113, U. S. DEPARTMENT OF AGRICULTURE. 
It is rarely found growing very far from the moist bottom lands 
and does not push its way up {he dry coulees toward the prairie 
levels. It is, however, a very useful tree for prairie planting, 
adapting itself readily to upland conditions, and has been known 
to persist in sod for a number of years after attaining reasonable 
size under cultivation. It may be classed as one of the best for 
shelter-belt planting in all types of soil throughout the entire region. 
- Green ash. — The green ash (Fraxinus lanceol-ata) is found in 
much the same range as the box elder. It prefers somewhat drier 
sites and often works its way up the long open coulees to the level 
of the prairie. In these situations it is frequently mixed with white 
elm, June berry, wild plum, buffalo berry, and chokecherry. It 
ranks with the box elder as one of the best trees for shelter-belt 
planting, doing well on all types of soil except sand and gravel, 
and it shows a marked ability to live through periods of extended 
drought. 
White elm. — The white elm (Ulmus americana) though generally 
considered a moisture-loving tree, is found in company with the 
green ash and buffalo berry in such comparatively dry situations as 
open valleys far removed from running water. Here it maintains 
itself in sod on the sides of dry runs. This occurs more generally 
at the western limit of its range, which is in eastern Montana and 
the Black Hills of South Dakota. In the Plains region it departs 
somewhat from its usual graceful shape, old trees at a distance 
resembling gnarled oaks. It is a good tree in shelter-belt plant- 
ings, showing a preference for clay soils. It is difficult to get seed 
for propagation, as the blossoms are often injured by the late spring 
frosts. 
Western cottonwood. — The western cottonwood (Populus deltoides 
var. occidentalis) is the dominant tree species along the larger river 
valleys of the Great Plains where it often attains great age, form- 
ing extensive open groves. It grows at some distance from its 
usual bottom-land habitat and may occasionally be found far up 
some dry run. It is a very good tree in shelter-belt planting 
throughout the area east of the Missouri Kiver; farther west, how- 
ever, it does not succeed as well. It adapts itself to either sand 
or clay soils, but is not to be recommended for dry situations. 
Balsam poplar. — The balsam poplar (Populus balsamifera) is 
found in the Black Hills in South Dakota: the Turtle Mountains, 
the Mouse River Valley, and on lake shores in the Coteau du Mis- 
souri in North Dakota : and possibly in the Little Rocky Mountains 
and the Sweet Grass Hills in Montana. The tree has not been 
planted for shelter-belt purposes except in a limited area south of 
the Turtle Mountains in Xorth Dakota. As it is essentially a 
