The plum when first known in Europe, as described by Pliny and other early writers, seems to have been a large and well-flavored fruit, indicating that it had been under cultivation for a long while. This, and the fact that the fruit was not known by the earliest writers on agriculture, indicate that the plum was not originally an inhabitant of southern Europe, as some suppose. It is likely that the tree has escaped from cultivation and become naturalized in the localities where it is now supposed to grow wild. _Prunus domestica_ has not been found wild nor under cultivation in eastern Asia, so far as can be learned by the botanical and horticultural explorers of China and nearby regions, _Prunus triflora_ being the domesticated plum of that part of the continent, though it may well be surmised that some of the Domestica plums are cultivated in western China, a region as yet but imperfectly explored for its plants. Having briefly sketched the origin of the Domestica plums in the Old World we may now consider their history in the New World—a more satisfactory task, as data are abundant and reliable. The Domestica plums are valuable food-producing trees in America but have not attained here the relative importance among fruits that they hold in Europe. From the earliest records of fruit-growing in the New World the plum has been grown less than the apple, pear, peach or cherry, while in Europe it is a question if it does not rank first or second among the tree-fruits. The comparatively restricted area which the Domestica plums now occupy in America is due, perhaps, to the fact that they do not possess in as high degree as the fruits named above the power of adaptation to the trans-Atlantic environment. Without question the feature of environment most uncongenial to plums in America is the climate. The plum thrives best in an equable climate like that of eastern and southern Europe and of western America, and cannot endure such extremes of heat and cold, wet and dry, as are found in parts of eastern America and in the Mississippi Valley. At best this fruit lacks in what is called constitution, or ability to withstand adverse conditions of any kind, whether of climate, culture, insects or fungi. Thus in America this plum suffers severely not only from climate but from several parasites, as curculio, black-knot, leaf-blight, plum-pockets and other pests.