Part 10 (1/2)

Happily man preserves and disseminates as well as destroys. The species will doubtless be preserved to science, and for ornamental and other uses, in its own and other lands; and the more remarkable individuals of the present day are likely to be sedulously cared for, all the more so as they become scarce.

Our third question remains to be answered: Have these famous Sequoias played in former times and upon a larger stage a more imposing part, of which the present is but the epilogue? We cannot gaze high up the huge and venerable trunks, which one crosses the continent to behold, without wis.h.i.+ng that these patriarchs of the grove were able, like the

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long-lived antediluvians of Scripture, to hand down to us, through a few generations, the traditions of centuries, and so tell us somewhat of the history of their race. Fifteen hundred annual layers have been counted, or satisfactorily made out, upon one or two fallen trunks. It is probable that close to the heart of some of the living trees may be found the circle that records the year of our Saviour's nativity. A few generations of such trees might carry the history a long way back. But the ground they stand upon, and the marks of very recent geological change and vicissitude in the region around, testify that not very many such generations can have flourished just there, at least in an unbroken series. When their site was covered by glaciers, these Sequoias must have occupied other stations, if, as there is reason to believe, they then existed in the land.

I have said that the redwoods have no near relatives in the country of their abode, and none of their genus anywhere else. Perhaps something may be learned of their genealogy by inquiring of such relatives as they have.

There are only two of any particular nearness of kin; and they are far away. One is the bald cypress, our Southern cypress, Taxodium, inhabiting the swamps of the Atlantic coast from Maryland to Texas, thence extending--with, probably, a specific difference--into Mexico. It is well known as one of the largest trees of our Atlantic forest-district, and, although it never--except perhaps in Mexico, and in rare instances--attains the portliness of its Western relatives, yet it may equal them in longevity. The other relative is Glyptostrobus, a sort of modified Taxodium, being about as much like our bald cypress as one species of redwood is like the other.

Now, species of the same type, especially when few, and the type peculiar, are, in a general way, a.s.sociated geographically, i.e., inhabit the same country, or (in a large sense) the same region. Where it is not so, where near relatives are separated, there is usually something to be explained.

Here is an instance. stance. These four trees, sole representatives of their tribe, dwell almost in three separate quarters of the world: the two redwoods in California, the bald cypress in Atlantic North America, its near relative, Glyptostrobus, in China.

It was not always so. In the Tertiary period, the geological botanists a.s.sure us, our own very Taxodium or bald cypress, and a Glyptostrobus, exceedingly like the present Chinese tree, and more than one Sequoia, coexisted in a fourth quarter of the globe, viz., in Europe! This brings up the question, Is it possible to bridge over these four wide intervals of s.p.a.ce and the much vaster interval of time, so as to bring these extraordinarily separated relatives into connection? The evidence which may be brought to bear upon this question is various and widely scattered. I bespeak your patience while I endeavor to bring together, in an abstract, the most important points of it.

Some interesting facts may come out by comparing generally the botany of the three remote regions, each of which is the sole home of one of these genera, i.e., Sequoia in California, Taxodium in the Atlantic United States,[V-1] and Glyptostrobus in China, which compose the whole of the peculiar tribe under consideration.

Note then, first, that there is another set of three or four peculiar trees, in this case of the yew family, which has just the same peculiar distribution, and which therefore may have the same explanation, whatever that explanation be. The genus Torreya, which commemorates our botanical Nestor and a former president of this a.s.sociation, Dr. Torrey, was founded upon a tree rather lately discovered (that is, about thirty-five years ago) in Northern Florida. It is a n.o.ble, yew like tree, and very local, being, so far as known, nearly confined to a few miles along the sh.o.r.es of a single river. It seems as if it had somehow been crowded down out of the Alleghanies into its present limited southern quarters; for in cultivation it evinces a northern hardiness. Now, another species of Torreya is a characteristic tree of j.a.pan; and one very like it, if not the same, inhabits the mountains of Northern China--belongs, therefore, to the Eastern Asiatic temperate region, of which Northern China is a part, and j.a.pan, as we shall see, the portion most interesting to us. There is only one more species of Torreya, and that is a companion of the redwoods in California.

It is the tree locally known under the name of the California nutmeg. Here are three or four near brethren, species of the same genus, known nowhere else than in these three habitats.

Moreover, the Torreya of Florida is a.s.sociated with a yew; and the trees of this grove are the only yew-trees of Eastern North America; for the yew of our Northern woods is a dec.u.mbent shrub. A yew-tree, perhaps the same, is found with Taxodium in the temperate parts of Mexico. The only other yews in America grow with the redwoods and the other Torreya in California, and extend northward into Oregon. Yews are also a.s.sociated with Torreya in j.a.pan; and they extend westward through Mantchooria and the Himalayas to Western Europe, and even to the Azores Islands, where occurs the common yew of the Old World.

So we have three groups of coniferous trees which agree in this peculiar geographical distribution, with, however, a notable extension of range in the case of the yew: 1. The redwoods, and their relatives, Taxodium and Glyptostrobus, which differ so as to const.i.tute a genus for each of the three regions; 2. The Torreyas, more nearly akin, merely a different species in each region; 3. The yews, still more closely related while more widely disseminated, of which it is yet uncertain whether they const.i.tute seven, five, three, or only one species. Opinions differ, and can hardly be brought to any decisive test. However it be determined, it may still be said that the extreme differences among the yews do not surpa.s.s those of the recognized variations of the European yew, the cultivated races included.

It appears to me that these several instances all raise the very same question, only with different degrees of emphasis, and, if to be explained at all, will have the same kind of explanation.

Continuing the comparison between the three regions with which we are concerned, we note that each has its own species of pines, firs, larches, etc., and of a few deciduous-leaved trees, such as oaks and maples; all of which have no peculiar significance for the present purpose, because they are of genera which are common all round the northern hemisphere. Leaving these out of view, the noticeable point is that the vegetation of California is most strikingly unlike that of the Atlantic United States.

They possess some plants, and some peculiarly American plants, in common--enough to show, as I imagine, that the difficulty was not in the getting from the one district to the other, or into both from a common source, but in abiding there. The primordially unbroken forest of Atlantic North America, nourished by rainfall distributed throughout the year, is widely separated from the western region of spa.r.s.e and discontinuous tree-belts of the same lat.i.tude on the western side of the continent (where summer rain is wanting, or nearly so), by immense treeless plains and plateaux of more or less aridity, traversed by longitudinal mountain-ranges of a similar character. Their nearest approach is at the north, in the lat.i.tude of Lake Superior, where, on a more rainy line, trees of the Atlantic forest and that of Oregon may be said to intermix. The change of species and of the aspect of vegetation in crossing, say on the forty-seventh parallel, is slight in comparison with that on the thirty-seventh or near it. Confining our attention to the lower lat.i.tude, and under the exceptions already specially noted, we may say that almost every characteristic form in the vegetation of the Atlantic States is wanting in California, and the characteristic plants and trees of California are wanting here.

California has no magnolia nor tulip trees, nor star-anise tree; no so-called papaw (Asimina); no barberry of the common single-leaved sort; no Podophyllum or other of the peculiar a.s.sociated genera; no nelumbo nor white water-lily; no p.r.i.c.kly ash nor sumach; no loblolly-bay nor Stuartia; no ba.s.swood nor linden-trees; neither locust, honey-locust, coffeetrees (Gymnocladus) nor yellow-wood (Cladrastis); nothing answering to Hydrangea or witch-hazel, to gum-trees (Nyssa and Liquidambar), Viburnum or Diervilla; it has few asters and golden-rods; no lobelias; no huckleberries and hardly any blueberries; no Epigaea, charm of our earliest Eastern spring, tempering an icy April wind with a delicious wild fragrance; no Kalmia nor Clethra, nor holly, nor persimmon; no catalpa-tree, nor trumpet-creeper (Tecoma); nothing answering to sa.s.safras, nor to benzoin-tree, nor to hickory; neither mulberry nor elm; no beech, true chestnut, hornbeam, nor iron-wood, nor a proper birch-tree; and the enumeration might be continued very much further by naming herbaceous plants and others familiar only to botanists.

In their place California is filled with plants of other types--trees, shrubs, and herbs, of which I will only remark that they are, with one or two exceptions, as different from the plants of the Eastern Asiatic region with which we are concerned (j.a.pan, China, and Mantchooria), as they are from those of Atlantic North America. Their near relatives, when they have any in other lands, are mostly southward, on the Mexican plateau, or many as far south as Chili. The same may be said of the plants of the intervening great Plains, except that northward in the subsaline vegetation there are some close alliances with the flora of the steppes of Siberia.

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along the crests of high mountain-ranges the Arctic-Alpine . flora has sent southward more or less numerous representatives through the whole length of the country.

If we now compare, as to their flora generally, the Atlantic United States with j.a.pan, Mantchooria, and Northern China--i.e., Eastern North America with Eastern North Asia, half the earth's circ.u.mference apart--we find an astonis.h.i.+ng similarity. The larger part of the genera of our own region, which I have enumerated as wanting in California, are present in j.a.pan or Mantchooria, along with many other peculiar plants, divided between the two. There are plants enough of the one region which have no representatives in the other. There are types which appear to have reached the Atlantic States from the south; and there is a larger infusion of subtropical Asiatic types into temperate China and j.a.pan; among these there is no relations.h.i.+p between the two countries to speak of. There are also, as I have already said, no small number of genera and some species which, being common all round or partly round the northern temperate zone, have no special significance because of their occurrence in these two antipodal floras, although they have testimony to bear upon the general question of geographical distribution. The point to be remarked is, that many, or even most, of the genera and species which are peculiar to North America as compared with Europe, and largely peculiar to Atlantic North America as compared with the Californian region, are also represented in j.a.pan and Mantchooria, either by identical or by closely-similar forms! The same rule holds on a more northward line, although not so strikingly. If we compare the plants, say of New England and Pennsylvania (lat.i.tude 450_470), with those of Oregon, and then with those of Northeastern Asia, we shall find many of our own curiously repeated in the latter, while only a small number of them can be traced along the route even so far as the western slope of the Rocky Mountains. And these repet.i.tions of East American types in j.a.pan

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and neighboring districts are in all degrees of likeness. Sometimes the one is undistinguishable from the other; sometimes there is a difference of aspect, but hardly of tangible character; sometimes the two would be termed marked varieties if they grew naturally in the same forest or in the same region; sometimes they are what the botanist calls representative species, the one answering closely to the other, but with some differences regarded as specific; sometimes the two are merely of the same genus, or not quite that, but of a single or very few species in each country; in which case the point which interests us is, that this peculiar limited type should occur in two antipodal places, and nowhere else.

It would be tedious, and, except to botanists, abstruse, to enumerate instances; yet the whole strength of the case depends upon the number of such instances. I propose therefore, if the a.s.sociation does me the honor to print this discourse, to append in a note a list of the more remarkable ones.[V-2] But I would here mention certain cases as specimens.

Our Rhus Toxicodendron, or poison-ivy, is very exactly repeated in j.a.pan, but is found in no other part of the world, although a species much like it abounds in California. Our other poisonous Rhus (R. venenata), commonly called poison-dogwood, is in no way represented in Western America, but has so close an a.n.a.logue in j.a.pan that the two were taken for the same by Thunberg and Linnaeus, who called them both R. vernix.