229 SCIENCE OF THE STUDY OF TREES. PART II. 
such as the bark, leaves, flowers, fruit, &c., are of importance. Not only are 
trees used in their different parts after being felled, but, in some cases, a part 
of their products is gathered yearly ; and some sorts, both of trees and shrubs, 
are in perpetual use in a living state, as fences for separation or enclosure, as 
avenues for shade, and as belts or screens for shelter. The ornament which 
trees and shrubs afford to gardens and grounds may also be considered as an 
important part of their use. 
The rearing and culture of trees form an important part of their economical 
history ; and require to be treated of, not only in the history of each individual 
species, but when treating of trees collectively in plantations. The commence- 
ment of the process of rearing is with the gathering of the seed, or the taking 
off of the cutting, or the forming of the layer ; and the termination of the pro- 
cess of culture is with the felling of the tree, or the cutting down of the shrub. 
CHAP. LY. 
SUMMARY OF PARTICULARS TO BE TAKEN INTO CONSIDERATION 
IN PREPARING THE DESCRIPTION, AND NATURAL AND ECONOMI- 
CAL HISTORY, OF TREES AND SHRUBS. « te 
in the three preceding chapters we have treated of the science of trees, as 
pictorial objects, or parts of general scenery ; as organised beings, or botanical 
objects ; and as forests or plantations, influencing the physical circumstances 
of a country, and the condition of man. Our object in those chapters was, 
to give a general idea of the extensive nature of the study of trees; and in 
the present chapter we propose to enumerate all the particulars which require 
to be taken into consideration in giving the specific character, description, 
history, and uses of each individual species, race, or variety. These parti- 
culars, arranged in the order in which they will stand in the succeeding part 
of this work, are as follows : — 
1. Classification. We shall adopt the natural system, chiefly for the sake of 
aiding us in generalising on the genera and species which each order and 
tribe contains; and we shall refer, for the definitions of these orders 
and tribes, to the writings of Professor De Candolle and Dr. Lindley, 
and more especially to the Prodromus of De Candolle, and Lindley’s 
Introduction to the Natural System, and to his modification of that work in 
his Key to Structural, Physiological, and Systematic Botany, published in 1835, 
2. Genera. The genera of each order or tribe, with their characters, will be 
given immediately after the general character of the order or tribe, in the 
manner of De Candolle, and as adopted by G. Don, in his edition of 
Miller’s Dictionary. 
3. Distinctive Characters. The species, races, or varieties, of each genus, 
will be enumerated immediately after the enumeration of the genera; and 
their distinctive characters will be given, with the English name, habit, co- 
lour of the flower, and time of flowering, and year of introduction into 
Britain. 
A. Identifications. These are references to some of the principal works 
in which the same plant has been described under the same name. 
B. Synonymes. These will be given to as great an extent as can be done 
with certainty, or apparent advantage. Not only will the scientific 
synonymes be given, but also those in common or ancient use in this 
country, and the popular names in other countries. : 
C. Derivations will be given, not only of the generic and specific names, 
but of all the synonymes, where doing so is likely to prove either m- 
structive or interesting. 
