202 Choice of Plant Material 
persistence rather than rapidity of growth should be looked 
for, keeping in mind that ultimate size must also be consid- 
ered with reference to the width of the street. 
With these points in mind we shall briefly examine the 
more common of our native species which lend themselves 
to ornamental planting, and such of the exotic, arbores- 
cent flora as have become thoroughly and generally estab- 
lished in our country; and finally give a few lists of species 
adapted to special situations and purposes. 
There are in existence several thousand species, varieties, 
and forms of trees, and perhaps not less than two thousand 
are found cultivated in parks and gardens, and of North 
American species alone nearly two hundred and fifty. But, 
if we confine ourselves to the consideration of the enumerated 
(nearly four hundred) species, we shall have at least included 
the best for general use. 
As we have said, adaptation to climate is a conditio sine 
gua non. Hence, we limit the enumeration of species 
adapted to climatic conditions in the Eastern States, north and 
south. Nor can we enter into an extensive discussion of 
the ornamental value of our many species. In this respect 
we may only give a few general hints, referring the reader 
to such discussions of this phase of the subject as are found 
in books on Landscape Gardening. 
A few general remarks regarding ornamental values and 
some other guiding points, which may accentuate essentials 
in this respect, and a few facts, known to the professional 
landscape gardener, but not often discussed in books, may 
well precede our enumeration. 
Ornamental value is in the first place a matter of indi- 
vidual taste; but there are standards of taste which it is well 
to consult before setting up one’s own standard. 
Since the impression of beauty is largely produced by the 
