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Show 220 DARWINIAN A. geographical distribution. The point to be remark:d is, that many, or even most, of th~ genera and spe~es which are peculiar toN or~h Amenca a~ compared w1th Europe, and largely pecuhar t? Atl.antiC ~ orth America as compared with the Cahforma~ re?wn, are. also represented in Japan and J\'Iantchoona, either by Identical or by closely-similar forms! The same ru!e.holds on a more northward line, although not so stnkmgly. If we compare the plants, say of New England and Pennsylvania (Jatitude 45°-4'7°), with those of Oregon, and thEm 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 repetitions of East American types in Japan and neighboring distri~ts ar~ i~ all.degrees of likeness. Sometirr:es the one ~s un~Istmgmshable from the other; sometimes there IS a difference of aspect, but hardly of tangible char~ct.er ;. 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 t'h is peculiar limited type should occur m. two antipodal places, and nowhere else. . It would be tedious, and, except to botamsts, ab-struse, to enumerate instances; yet the whole stren~th of the case depends upon the number of such m- SEQUOIA AND ITS HISTORY. 221 stances. ·I propose therefore, if the Association does me the honor to print this discourse to append in a note a list of the more remarkable one~. 1 But I would here mention certain cases as specimens. Our Rhus To;xicodendron, or poison-ivy, is very exactly repeated In Japan, 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 analogue in Japan that the two were taken for the same by Thunberg and J ... innreus, who ca1led them both R. vernix. Our northern fox-grape, Vitis Labrusca, is wholly confined to the Atlantic States, except that it reappears in Japan and that region. . The o.riginal Wistaria is a woody leguminous chmber With showy bloss0ms, native to the middle Atlantic States·; the other species, which we so much prize in cultivation, W. Sinensis, is from China, as its name denotes, or perhaps only from Japan, where it is certainly indigenous. Our yellow-wopd (Oladrastis) inhabits a very limited district on the western slope of the Alleghanies. Its only and very near relative, . Maackia, is confined to Mantchooria. The Hydrangeas have some species in our Alleghany ~egion : all the rest belong to the Chino-Japanese reg10n and its continuation westward. The same may be said of Philadelphus, except that there are one 1 • The ~~bulated list referred to was printed as an appendix to. the offimal edition of this discourse, but is here omitted. |
