198 Choice of Plant Material 
wise being no more subject to insect pests than many other 
species which are supposed to be immune, because the 
opportunity for extraordinary multiplication of its enemies 
has not been given. 
General Considerations. In addition to economic tree- 
planting for orchard and forestry purposes, which lie out- 
side the scope of this book, there are three objects for which 
trees are planted, namely, shade, ornament, and botanical 
interest. The selection of plant material will in the first 
place be influenced by the prominence which one or the 
other of these objects may assume, and it will in addition 
be circumscribed by the situation and space at command. 
Different points of view will guide the selection for street 
and avenue planting, for planting in yards and small places, 
for planting on lawns in small or large parks, and for plant- 
ing with special purposes in view, like the binding of shore 
or dunes. 
In all cases, however, except where the botanical interest 
—14é., the collection of specimen trees — is uppermost, 
the two paramount considerations are adaptation to climate 
and adaptation to soil. 
While in street planting and in public parks, only trees 
of proven adaptability should be used, in other cases experi- 
ment is not excluded, although there should be at least a 
reasonable expectation of success to warrant the choice, 
which should be made with a knowledge of the points dis- 
cussed in Chapter ITI, concerning the selection from local- 
ities of the most unfavorable climate in which the species is 
at home, or at least from a locality which compares most 
nearly to that to which the specimen is to be transferred. 
As regards adaptation to soil, we must emphasize again 
that in most cases physical conditions, especially of water- 
supply, are of more moment than chemical composition; 
