As _Prunus americana_ is more carefully studied throughout the great territory it inhabits, undoubtedly one or more sub-species will be described. The plums of this species in the Mississippi Valley are distinguished from the eastern and typical form by fruits having a length greater than the diameter, by a somewhat different aspect of tree and by flatter seeds which are usually conspicuously longer than broad. All of the cultivated varieties come from the western form. The plant of _Prunus americana_ in the dry plain regions in Kansas and Nebraska becomes shrubby in character while on the alluvial bottom lands along the streams in this region it retains the character of a tree. In the southern limit of its range, the leaves of this species are more or less pubescent on the lower surface. As the species occurs throughout western New Mexico, Colorado, Utah, Wyoming, Montana and Manitoba, it differs enough, possibly, from the eastern types to be considered a sub-species, having a wholly different aspect of tree, silvery and somewhat scurfy twigs, smaller, thinner and lighter colored leaves and smaller fruits with more roundish stones. _Prunus americana_ is the predominating native plum. It is the most widely distributed, is most abundant in individual specimens and has yielded the largest number of horticultural varieties of any of the native species. Because of its prominence and comparatively high degree of permanency of characters it may well be considered the type from which has sprung not only its botanical varieties but several other of the American species. Its variability, too, is shown in its many diverse horticultural varieties, and of its adaptability it may be said that it flourishes on nearly all soils and exposures, and is found wild or cultivated from Maine to Florida and northward from Mexico along the eastern slope of the Rocky Mountains well into Canada. The species was well named by Marshall “Americana.” This plum has not played nearly as important a part in the pomology of America as its merits would warrant. It seems to have made an impression almost from the first upon the Europeans who settled America, for it is mentioned in nearly all the early records of the food products of the newly found land, yet its cultivation can hardly be said to have begun until the last half of the Nineteenth Century. But the early descriptions of this and other native plums by the colonial explorers, naturalists and botanists, show but little interest in these fruits as subjects for cultivation, and seem to contain almost no prophecies as to the possible development of a new orchard plant from them. It is probable that the Damsons, which were early introduced in America, and the Domesticas, which came at least before the Revolution, proved so adaptable to the part of the New World in which the colonies were planted that this, even though the best of the wild plums, offered small reward in comparison.