Our Rhus Toxicodendron, 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 Linnaeus, who called 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 original Wistaria is a woody leguminous climber with showy blossoms, 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-wood (Cladrastis) 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 region:  all the rest belong to the Chino-Japanese region and its continuation westward.  The same may be said of Philadelphus, except that there are one or two mostly very similar species in California and Oregon.

Our May-flower (Epigaea) and our creeping snowberry, otherwise peculiar to Atlantic North America, recur in Japan.

Our blue cohosh (Caulophyllum) is confined to the woods of the Atlantic States, but has lately been discovered in Japan.  A peculiar relative of it, Diphylleia, confined to the higher Alleghanies, is also repeated in Japan, with a slight difference, so that it may barely be distinguished as another : species.  Another relative is our twin-leaf (Jeffersonia) of the Alleghany region alone:  a second species has lately turned up in Mantchooria.  A relative of this is Podophyllum, our mandrake, a common inhabitant of the Atlantic United States, but found nowhere else.  There is one other species of it, and that is in the Himalayas.  Here are four most peculiar genera of one family, each of a single species in the Atlantic United States, which are duplicated on the other side of the world, either in identical or almost identical species, or in an analogous species, while nothing else of the kind is known in any other part of the world.

I ought not to omit ginseng, the root so prized by the Chinese, which they obtain from their northern provinces and Mantchooria, and which is now known to inhabit Corea and Northern Japan.  The Jesuit Fathers identified the plant in Canada and the Atlantic States, brought over the Chinese name by which we know it, and established the trade in it, which was for many years most profitable.  The exportation of ginseng to China probably has not yet entirely ceased.  Whether the Asiatic and the Atlantic American ginsengs are to be regarded as of the same species or not is somewhat uncertain, but they are hardly, if at all, distinguishable.