200 Choice of Plant Material 
protection which may enable a specimen of a half-hardy 
species to endure adverse climatic conditions. And, finally, 
there is such a thing as individual hardiness, a given speci- 
men enduring what the species in general may not be ex- 
pected to survive. 
Again, local variation of climatic conditions, due to aspect 
and protection against winds, is quite remarkable. Thus 
the north or the south slope, the top of a hill or a depression, 
often produces sufficient difference to enable a species to 
thrive in the one and not in the other limited locality, 
although the two may be only a few hundred yards apart. 
We may not, therefore, draw valid conclusions from single 
observations, and the word “hardy” may only be under- 
stood in general terms. 
For determination of the likelihood of hardiness, we have 
referred to a publication of the Canadian Experiment 
Farms, by Dr. Wm. Saunders, in which are given the results 
of long-continued tests of a very extensive list of trees and 
shrubs in the untoward climate of Ottawa, Manitoba, and 
the Northwestern Territories.* 
Besides the two paramount considerations of climatic and 
soil-adaptation, the following points will enter into the 
selection of plant material. 
1. Ornamental value; which depends upon outline, habit 
of growth, and final form of crown, as well as upon character, 
shape, arrangement, and color of foliage and bark, the 
autumnal tints to which it changes, and, although in a minor 
degree in trees, on flowers, fruit, and bark. 
2. Shading value; which depends not only on the size, 
form, and density of the foliage, but also on leaf period, i.e., 
the earlier or later leafing-out and the earlier or later fall 
of foliage. 
1 Bulletin No 47, 1904. 
