Without dwelling on the Arctic regions, then, we may divide this immense country into two regions; one of which, descending as far as 36°, may be called the Northern region; the other, comprehended between 36° and 30° of latitude, will constitute the Southern region. The Northern region well deserves to be called the region of _Aster_ and _Solidago_; those beautiful composites abound there with _Liatris_, _Rudbeckia_, and _Galardia_, of the same family. _Œnothera_, _Clarkia_, _Andromeda_, and _Kalmia_, charming ornamental plants, well known in our flower gardens, likewise characterize this vegetable zone. Among the most abundant arborescent species, we may mention numerous species of pine, fir, larch, _Thuja_, juniper; no less than twenty-seven species of willow; twenty-five of oak, beeches, chestnuts, elms, hornbeams, alders, birches, poplars, and ashes. With these are mingled the American plane, _Liquidambar_, the trunk and branches of which furnish juices used in medicine; the tulip-tree, with singularly truncate leaves and large, spreading, solitary, yellowish flowers; different species of maple, lime, _Robinia_, and walnut. Together with these numerous and varied arborescent species, which attain considerable dimensions, grow the _Myrica cerifera_, which furnishes an abundant wax drawn from the fruit by boiling; the currant (_Ribes_), with colored and ornamental flowers in great varieties of red, yellow, and white; the elegant _Andromeda_, _Azalea_, _Rhododendron_, and _Spiræa_, present themselves in endless varieties; sumacs, a species of which (_Rhus toxicodendron_), with greenish yellow flowers, contains a juice so acrid that contact with it produces blisters and erysipelas, and is a dangerous poison; _Ceanothus_, hollies, and buckthorns.