The cause of the superior tinting of the American forest, compared with that of Europe, has never been satisfactorily explained, though it seems to be somewhat inexplicably connected with the brightness of the American climate.  It is a subject that has not engaged the attention of scientific travellers, who seem to have regarded it as worthy only of the describer of scenery.  It may, however, deserve more attention as a scientific fact than has been generally supposed,—­particularly as one of the phenomena that perhaps distinguish the productions of the eastern from those of the western coasts of the two grand divisions of the earth.  I have observed that the Smoke-tree, which is a Sumach from China, and the Cydonia Japonica, are as brightly colored in autumn as any of our indigenous shrubs; while the Silver-Maple, which, though indigenous in the Western States, probably originated on the western coast of America, shows none of the fine tinting so remarkable in the other American Maples.  These facts have led me to conjecture that this superior tinting of the autumnal foliage may be peculiar to the eastern coasts both of the Old and the New Continent, in the northern hemisphere.  May not this phenomenon bear some relation to the colder winters and the hotter summers of the eastern compared with the western coasts?  I offer this suggestion as a query, not as a theory, and with the hope that it may induce travellers to make some particular observations in reference to it.

The indigenous trees of America, or rather of the Atlantic side of this continent, are remarkable not only for their superior autumnal hues, but also for the shorter period during which the foliage remains on the trees and retains its verdure.  Our fruit-trees, which are all exotics, retain their foliage long after our forest-trees are leafless; and if we visit an arboretum in the latter part of October, we may select the American from the foreign species, by observing that the latter are still green, while the others are either entirely denuded, or in that colored array which immediately precedes the fall of the leaf.  The exotics may likewise be distinguished in the spring by their precocity,—­their leaves being out a week or ten days earlier than the leaves of our trees.  Hence, if we take both the spring and autumn into the account, the foreign, or rather the European species, show a period of verdure of three or four weeks’ greater duration than the American species.  Many of the former, like the Weeping Willow, do not lose their verdure, nor shed their leaves, until the first wintry blasts of November freeze them upon their branches and roll them into a crisp.