There is a shrub, Elliottia, which is so rare and local that it is known only at two stations on the Savannah River in Georgia.  It is of peculiar structure, and was without near relative until one was lately discovered in Japan (Tripetaleia), so like it as hardly to be distinguishable except by having the parts of the blossom in threes instead of fours—­a difference not uncommon in the same genus, or even in the same species.

Suppose Elliottia had happened to be collected only once, a good while ago, and all knowledge of the limited and obscure locality were lost; and meanwhile the Japanese form came to be known.  Such a case would be parallel with an actual one.  A specimen of a peculiar plant (Shortia galacifolia) was detected in the herbarium of the elder Michaux, who collected it (as his autograph ticket shows) somewhere in the high Alleghany Mountains, more than eighty years ago.  No one has seen the living plant since or knows where to find it, if haply it still flourishes in some secluded spot.  At length it is found in Japan; and I had the satisfaction of making the identification.[V-3] A relative is also known in Japan; and a less near one has just been detected in Thibet.

Whether the Japanese and the Alleghanian plants are exactly the same or not, it needs complete specimens of the two to settle.  So far as we know, they are just alike; and, even if some difference were discerned between them, it would not appreciably alter the question as to how such a result came to pass.  Each and every one of the analogous cases I have been detailing—­and very many more could be mentioned—­raises the same question, and would be satisfied with the same answer.

These singular relations attracted my curiosity early in the course of my botanical studies, when comparatively few of them were known, and my serious attention in later years, when I had numerous and new Japanese plants to study in the collections made, by Messrs. Williams and Morrow, during Commodore Perry’s visit in 1853, and especially, by Mr. Charles Wright, of Commodore Rodgers’s expedition in 1855.  I then discussed this subject somewhat fully, and tabulated the facts within my reach.[V-4]

This was before Heer had developed the rich fossil botany of the arctic zone, before the immense antiquity of existing species of plants was recognized, and before the publication of Darwin’s now famous volume on the “Origin of Species” had introduced and familiarized the scientific world with those now current ideas respecting the history and vicissitudes of species with which I attempted to deal in a moderate and feeble way.