Page:Popular Science Monthly Volume 1.djvu/747

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731
ON THE DERIVATION OF AMERICAN PLANTS.

published, have now been for some years made known, thanks mainly to the researches of Heer upon ample collections of arctic fossil plants. These are confirmed and extended by new investigations, the results of which have been indicated to me by the latter. The taxodium, which everywhere abounds in the Miocene formations in Europe, has been specifically identified, first by Goeppert, then by Heer, with our common cypress of the Southern States. It has been found, fossil in Spitzbergen, Greenland, and Alaska, in the latter country along with the remains of another form, distinguishable, but very like the common species; and this has been identified by Lesquereux in the Miocene of the Rocky Mountains. So there is one species of tree which has come down essentially unchanged from the Tertiary period, which for a long while inhabited both Europe and North America, and also at some part of the period the region which geographically connects the two (once doubtless much more closely than now), but survives only in the Atlantic United States and Mexico. The same Sequoia which abound in the same Miocene formations in North Europe has been now abundantly found in those of Iceland, Spitzbergen, Greenland, Mackenzie River, and Alaska. It is named Sequoia langsdupii, but is pronounced to be very much like Sequoia sempervirens, our living redwood of the Californian coast—to be the ancient representative of it. Fossil specimens of a similar, if not the same, species have been recently detected in the Rocky Mountains by Hayden, and determined by our eminent paleontological botanist, Lesquereux, and he assures me that he has the common redwood itself from Oregon, in a deposit of Tertiary age. Another Sequoia (Sequoia stembergii), discovered in Miocene deposits in Greenland, is pronounced to be the representative of Sequoia gigantea, the big tree of Californian sierra. If the taxodium of the Tertiary time in Europe and throughout the arctic regions is the ancestor of our present bald cypress, which is assumed in regarding them as specifically identical, then I think we may with our present light fairly assume that the two redwoods of California are the probable descendants of the two ancient species which so closely resemble them. The forests of the arctic zone in Tertiary times contained at least three other species of Sequoia, as determined by their remains, one of which, from Spitzbergen, also much resembles the common redwood of California. Another, "which appears to have been the commonest coniferous tree on Disco," was common in England and some other parts of Europe. So the Sequoias, now remarkable for their restricted station and numbers, as well as for their extraordinary size, are of an ancient stock; their ancestors and kindred formed a large part of the forests which flourished throughout the polar regions, now desolated and ice-clad, and which extended into low latitudes in Europe. On this continent one species at least had reached to the vicinity of its present habitat before the glaciation of the region. Among the fossil specimens already found