trees and the birches which form a characteristic boreal forest zone of similar features throughout the entire land area of the cold temperate region from Kamschatka to Alaska. Farther south, as the land masses diverge, the forest types show a decreasing likeness—yet the broad-leaved woodlands of oak, beech and others are readily recognized as such in both the old and the new worlds.
A number of American trees, however, and these characteristic of the more southern portion of the Atlantic forest, have no European counterparts. We look in vain through the forests of Europe for such familiar forms as the hemlock, the hickories, the tulip tree, the magnolias, the sassafras, the tupelo gums, the witchhazel, the Kentucky coffee tree, the yellow-wood, the locusts, the catalpa and the liquidambar. Strange as it may appear, nearly all of these eastern American forms occur nowhere else in the world save in eastern Asia, in the more temperate parts of China and Japan, where the same or very nearly related species are to be found. What is even still more striking is the contrast between the Atlantic and Pacific sides of North America. Excepting along the mountain crests where the more or less world-wide boreal plants find a congenial environment, the vegetation of the California region is related mainly to the dry plateau lands of Mexico and South America. So far as the trees are concerned a native of the eastern United States would find himself in much more homelike surroundings in the woodlands of temperate China and Japan than on the Pacific slope of his own country. A tulip tree, very similar to the one at home, almost if not the identical species of sassafras, numerous closely related magnolias, a near relative of the southern yellow-wood, the liquidambar, the catalpa, the coffee tree, the hemlock, and other forms appear as familiar trees in the landscape of China and Japan. This likeness between the two widely separated regions is not confined to the trees alone. The flora at large presents many features in common. The fox grape, the poison ivy, the hydrangeas, the wistaria, the blue cohosh, the may-apple, the twinleaf, the trailing arbutus or may-flower, and the creeping snowberry have each a more or less closely related form in eastern North America and eastern Asia, but are found in no other part of the world.
This likeness between the forest types of eastern North America and eastern Asia dates from a period far back in the history of northern lands. The tertiary deposits of Greenland and Spitzbergen have yielded numerous fossil remains of trees, among them a magnolia, a tulip tree, a sassafras and a liquidambar, quite similar, if not, in some cases, identical with the species now living. Besides these forms that are peculiar to the regions above named, the remains of other trees of more wide-spread distribution have been found in Greenland—a basswood, a plane tree, a persimmon, also several kinds of beeches, birches,
