CHAP. III. NATURAL AND ECONOMICAL USES. 219 



and cultivated, there will not, we may presume, be that desire, which now 

 seems to exist among botanists, to increase the number of species. Formerly, 

 and more especially among the disciples of Linnanis, the great business of the 

 botanist was to collect, name, and describe plants. These were then the 

 highest departments of the science ; but, now, the anatomical, physiological, 

 and chemical studies of plants occupy that station ; and the naming and de- 

 scribing of species is considered as comparatively mechanical. 



The other cause which has contributed to increase the number of supposed 

 species is, the natural eagerness of botanical collectors, sent abroad in order to 

 discover novelties, to find something new, in order to answer the end for which 

 they were sent out. This is very natural : and where there is a strong desire for, 

 and also an important interest concerned in, obtaining anything, either the thing 

 sought for, or something like it, will be found. Hence the young and ardent 

 collector will seize upon every variation produced by climate, soil, situation, 

 age, or even accident, to add another specimen to his herbarium ; which enables 

 the botanist at home to add another name to the number of his species. This 

 we believe to be much more frequently done from practical inexperience, than 

 from any intention to deceive; so different is the appearance which plants pre- 

 sent in a wild state and in a state of cultivation, and, often, in one country 

 from what they do in another country; and so difficult is it to judge of an 

 entire tree by a dried specimen, perhaps only a few inches in length. This 

 state of things, in the comparative infancy of botanical science, is perhaps un- 

 avoidable ; and it is, doubtless, erring on the safe side, to collect and bring home 

 every thing that can be at all considered as distinct, leaving it to cultivators 

 and botanists to determine afterwards whether it is really so. It is proper, 

 however, to notice this state of things, to aid in accounting for the present 

 state of confusion and uncertainty in the names and characters of trees and 

 shrubs; and to show the little faith that is to be placed in botanical descrip- 

 tions drawn up from dried specimens of any kind,and more especiallyfroin those 

 procured by inexperienced collectors. If this may be considered as applicable 

 to plants generally, it is more particularly so in the case of trees and shrubs ; 

 which, from the long period which they require to attain maturity, naturally 

 assume very different appearances under different circumstances : and which, 

 therefore, require to be studied, not only in the same locality, but in different 

 localities, for a number of years, before any decided opinion can be pro- 

 nounced respecting which are species and which are varieties. 



It will not, we trust, be supposed, from these observations, that we intend 

 to set ourselves up as a model for imitation, in determining species and de- 

 scribing them ; on the contrary, we value the Arboretum part of this Encyclo- 

 ptsdia much more, as containing only the names of such things as we know to 

 be really distinct, and actually in existence in England, than for its pretensions 

 in a purely botanical point of view. 



CHAP. III. 



TREES AND SHRUBS CONSIDERED WITH REFERENCE TO THEIR 

 USES IN THE ECONOMY OF NATURE AND TO MAN. 



THE large proportion which the ligneous vegetation of the earth's surface 

 bears to its herbage, and the immense extent of the forests in comparison with 

 that of the meadows, pastures, or plains, which it contains, seem to indicate 

 that trees and shrubs act an important part in the economy of our globe. 

 In countries uninhabited by man, the influence of forests must be on the 

 climate, on the soil, and on the number of wild animals and herbaceous 

 vegetables. In civilised countries, to these influences must be added the 



