10 INTRODUCTION. 
our most valuable plants, whether in agriculture, horticulture, 
or floriculture, are more or less indebted for their excellence 
to art. Our cultivated fruit trees are very different from the 
same trees in a wild state; and our garden and field herbaceous 
vegetables so much so, that, in many instances, not even a 
botanist could recognise the wild and the cultivated plant to be 
the same species. ‘There is reason to believe that the same 
means by which we have procured our improved varieties of 
fruit trees will be equally effective in producing improved varie- 
ties of timber trees. A few species, such as the oak, the elm, 
the magnolia, &c., have had improved varieties raised from seed 
by accidental crossing, or by the selection of individuals from 
multitudes of seedlings; and variegated varieties, and varieties 
with anomalously formed leaves, or with drooping or erect shoots, 
have been procured from the sports of parts of different plants. 
But the mode of improvement by cross-fecundation is yet quite 
in its infancy with respect to timber trees; and to set limits to 
the extent and beauty of the new varieties which may be pro- 
duced by it is impossible. ‘There is no reason why we may not 
have a purple-leaved oak, or elm, or ash, as well as a purple- 
leaved beech; or a drooping sweet chestnut as well as a drooping 
ash. ‘The oak is a tree that varies astonishingly by culture; 
and, when the numerous American varieties that have been 
introduced into this country shall have once begun to bear seed, 
there is no end to the fine hybrids that may be originated be- 
tween them and the European species. In short, we see no 
difficulty in improving our ornamental trees and shrubs to as 
great an extent as we have done our fruit trees and shrubs; 
though we are as yet only procuring new species from foreign 
countries, which may be considered as the raw material with 
which we are to operate. . 
Part LV., which will form the last division of the Arboretum 
et Fruticetum Britannicum, will be devoted to selected lists of the 
trees and shrubs described, classified according to their different 
capacities for fulfilling the various purposes for which trees and 
shrubs are required by the planter and by the landscape-gar- 
dener. For the rest we refer to the Table of Contents. 
The utility of such a Work as the Arboretum et Fruticetum 
Britannicum to the gardening world, and to the landed pro- 
prietor, will not, we think, be questioned. We shall say nothing, 
therefore, of the influence which it cannot fail to have in pro- 
moting a taste for the culture and spread of such foreign trees 
as we have already in the country; and in exciting a desire for 
introducing others from different parts of the world, and for 
originating new varieties by the different means employed by 
art for that purpose. One remark, however, we may be per- 
mitted to make on the use of such a Work as the Arboretum et 
Fruticetum Britannicum to gentlemen of landed praperty. Every 
