al 
immense range of conditions, illustrating well the possibility of adap- 
tation which a single species may have. 
All species possess to a greater or less degree the power of with- 
standing varying conditions, but for each there is an ascertainable 
degree of heat (and presumably of moisture and light) at which it grows 
best. In tree culture the character of the soil is important principally 
(one might say only) in so far as it affects the amount of moisture and 
heat available for the trees; and the lay of the land—exposure—is also 
to be considered principally with reference to heat, light, and moisture. 
HEAT. 
The heat requirement of plants in the open can be controlled to only 
a Slight degree by the cultivator. He may frequently guard against 
frost by care in the selection of a site for the plantation, and the evil 
effects of hot winds may sometimes be avoided in the same way; but 
this is less true in the plains, where there are relatively smaller differ- 
ences in the elevation of the iand than within the forested area. 
As a rule, species must from the first be sufficiently hardy to with- 
stand the extremes of heat and cold to which they will be subjected 
where planted. Hardiness is usually regarded as the ability of a 
species to withstand cold, but it is quite as important to consider also 
its heat resistance. The Butternut (Juglans cinerea) is not generally 
hardy in the plains, though native along the streams of lowa and 
Minnesota as far north as Minneapolis. It suffers from sun scald in 
plantations, and hence can not be considered hardy. The Catalpa and 
Russian Mulberry, while successful in eastern Kansas, fail in the west- 
ern part of that State in much the same way that they do in northern 
Nebraska, though the winter climate in western Kansas is but little, 
if any, colder than that of the eastern part of the State. Light and 
moisture evidently have an influence in determining hardiness, as well 
as heat; in this, as in the rate of growth, all three factors are important 
and can not be dissociated. Classified with regard to their ability to 
endure cold. the species usually available for planting in the West 
would stand about as follows, the hardiest being named first: 
First group.—Aspen, White Spruce, Yellow Birch, Sweet Birch, Jack 
Pine, White Pine, Red Pine, Norway Spruce, Red Cedar, Scotch Pine, 
Austrian Pine, White Elm, Cottonwood, Boxelder, Green Ash (for North 
Dakota and northern Minnesota). 
Second group.—Rock Pine (Bull Pine), Douglas Spruce, Hackberry, 
White Willow, Black Cherry, Bur Oak, Red Oak, White Ash, Silver 
Maple (for South Dakota and northern Nebraska). 
Third group.—Chestunut, Black Walnut, White Oak, Cow Oak, Hick- 
ory, Honey Locust, Kentucky Coffee Tree, Black Locust, Catalpa, 
Russian Mulberry, White Fir (for south Nebraska and Kansas). 
Fourth group.—Pecan, Osage Orange, Shortleaf Pine, Mesquit, 
Chinaberry (for Oklahoma and Texas). 
