The botanical differences between these Asiatic plums and those from Europe and America are most interesting. In 1859 Asa Gray called attention to the striking resemblances between the east coast floras of Asia and America. The Triflora plum is one of the plants which furnishes substantial evidence of this similarity and of the dissimilarity of the east and west coast floras of the two hemispheres. In general aspect the trees of the Triflora plums in summer or winter are much more like those of the American species than like those from Europe or West Asia; so, too, the fruits are more alike in appearance and in quality, and the peach-like foliage of the Trifloras might easily be mistaken for that of some of our varieties of Hortulana or Munsoniana. In the manner in which the buds are borne and in vernation the resemblance of the Oriental species to the Americanas, Hortulanas and Munsonianas is again most striking. In Asiatic and American species the buds are borne in twos and threes, while in the European species they are more often single or double. The importance of this similarity of the Triflora plums to the most common American species is seen when Gray’s reason for the likenesses between the two floras is considered. This, briefly, is that similar types of post-glacial plants should persist in areas having like geographical positions and like climates; hence east-coast plants in one hemisphere should be expected to be similar to those of the east coast of the other hemisphere and the same with the west coast. Triflora plums are near of kin to American plums, then, because they have been evolved under similar conditions. This is a reason why these plums from Japan are adapted to so wide a range of country in America, and why, too, they are so free from the fungus troubles which attack European plums, but from which American plums suffer but little. As might be expected from their nearness of kin the Triflora plums hybridize readily with the American species and especially with the Hortulanas and Munsonianas, the species they most resemble. Unfortunately an amalgamation of the Oriental plums with the Americanas is not so easily accomplished and that with the Domesticas is still more difficult. Hybrids with _Prunus simonii_ are easily made and the progeny as a rule have much merit. Hybrids of the Trifloras with our native species give most promising results, a number of them being described in _The Plums of New York_. The fact that the Trifloras have been cultivated for several centuries, at least, means in their hybridization with American species that there is an amalgamation of domesticated characters with the similar but wilder characters of our native species.