ON THE DERIVATION OF AMERICAN PLANTS, ytg 



* where 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. 

 One other relative is also shown in Japan ; and another 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 came to be known between them, it would not appre- 

 ciably 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 cf which I could adduce very many more raises the same ques- 

 tion, and would be satisfied with the same answer. These singular re- 

 lations 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 Morris, Williams, and Morrow) 

 during Commodore Perry's visit in 1853, and especially, by Mr. 

 Charles Wright, in Commodore Rodgers's expedition in 1855. I then 

 discussed this subject somewhat fully, and translated the facts within 

 my reach. This was before I ever 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 Dar- 

 win's now famous volume on the " Origin of Species " had introduced 

 and familiarized the scientific world with those now current ideas re- 

 specting the history of species, with which I attempted to deal in a 

 moderate and feeble way. My speculation was based upon the former 

 glaciation of the northern temperate zone, and the inference of a 

 warmer period preceding (and, perhaps, following). I considered that 

 our own vegetation, or its proximate ancestry, must have occupied the 

 arctic and sub-arctic regions in Pliocene times, and that it had been 

 gradually pushed southward as the temperature lowered and the 

 glaciation advanced even beyond its present habitation; that plants 

 of the same stock and kindred, probably ranging round the arctic zone 

 as the present arctic species do, made their forced migration south- 

 ward upon widely-different longitudes, and receded moi*e or less as the 

 climate grew warmer ; that the general difference of climate which 

 marks the eastern and the western sides of the continents the one 

 extreme, the other mean was doubtless even then established, so that 

 the same species and the same sort of species would be likely to secure 

 and retain foothold in the similar climates of Japan and the Atlantic 

 United States, but not in intermediate regions of different distribution 

 of heat and moisture ; so that different species of the same genus as in 

 torreya, or different genera of the same group, as Redwood, taxodium 

 and glyptostribus, or different associations of forest-trees, might estab- 

 lish themselves each in the region best suited to their particular re- 



