FORESTS AND TREES OF NORTH AMERICA. 275 



audi will merely allude to its connexion with, though not dependence on, 

 the peculiarities of our climate. We have with a tropical summer a tro- 

 pical variety of trees, hut chiefly of northern forms. Again, with our 

 arctic winters we have a group of trees, which, though of tropical forms, 

 are so adapted to the climate as to lose their leaves, like the northern 

 forms, in winter. But here, it must he distinctly understood, is no 

 alteration produced hy climate. The trees were made for and not by 

 the climate, and they keep their characteristics throughout their v»'hole 

 range, which with some extends through a great variety of climate. 

 I will not stop to discuss the relations of f-pecific distinctions and ex- 

 ternal physical influences, assuming that the reader understands the 

 scientific vie^vs of the suhject. Besides the connexion between the 

 Avinter climate and the deciduous trees, we find a remarkable instance 

 of a similar character in the great forests of pines which appear in our 

 subtropical southern borders, and with them a cypress, chiefly a sub- 

 tropical form of the Coniferae, which, unlike all others, loses its leaves 

 in winter like northern trees. Thus, as our climate shows great ex- 

 tremes, so do the forms of vegetation adapted for it; and the very wide 

 distribution of many of these forms may be considered by some a proof 

 of the great past duration of the same climate, on the supposition that 

 each species has spread slowly from a narrow centre of creation. 



Another marked climatic connexion is that of the moisture annually 

 deposited on this province. I need not prove to those who have 

 studied the suhject that this is one of the most essential elements for 

 the grov/th of forests of all kinds of trees. The dense growth of the- 

 ever-rainy tropics in some parts of the world, with the bare plains &r 

 deserts of other equally tropical countries which have little or no rain, 

 prove that heat alone has little influence. On the other hand, our 

 Lacustrian Province is densely wooded almost to the limits of perpetual 

 frost, while the Steppes of Siberia, though of similar temperature, have 

 little or no wood, being supplied with little moisture. Other proofs 

 will be referred to hereafter. But besides the total amount, the cc^ual 

 distribution of the rains is important, as will be seen when we speak 

 of regions having a dry and a wet season alternately. 



V/ithout going further into this interesting subject here, 1 will say 

 that I believe the reader, upon close study of it, will come to the con- 

 <;lusion that so intimate a relation exists between the trees and the 

 climate of this Apalachian Province that their peculiarities always 

 have and always must exist together. The disadvantages we feel in 

 the climate are in this way compensated for, and will in time be looked 

 upon as among the greatest natural advantages of the country. The 

 midday heat, by rarefaction and evaporation, brings northward from 

 the Gulf its abundant moisture. After several hours or days the cold 

 westerly or northerly wind condenses this in rain over all that part of 

 the continent included in this province, and in a less amount for some 

 distance west and north of it. Thus in summer a continual supply is 

 provided, while in winter the same winds which condense the summer 

 rains become our most dreaded arctic blasts. 



The Lacustrian Province does not derive much moisture from the 

 Gulf winds, but while its colder climate makes evaporation slower, it 

 receives a share both from its own waters and probably also from the 



