The description of this species is based on both wild and cultivated material, and the variety Arkansas may be considered as a typical representative. Type specimens, deposited in the Economic Collection of the United States Department of Agriculture, were collected by W. F. Wight (flowers) at the New York State Experiment Station, Geneva, New York, No. 2721, May 15, 1909, and (foliage) at the Iowa Experiment Station, Ames, Iowa, No. 4178, September 15, 1909. This species differs from _Prunus angustifolia_, with which it has long been confused, chiefly in being a much larger plant, a true tree while the other seldom reaches the size of a tree. It has coarser and less twiggy branches, shaggier bark and less red in the color of the young wood. The leaves are larger, thicker, more truly lanceolate in shape, less folded, a lighter green and less glossy. The flowers of the new species are larger, fewer in number, borne in less dense umbels which are not so nearly sessile as those of the older species and are borne on longer pedicels. The calyx-lobes are erect in this species and reflexed in _Prunus angustifolia_, strongly marked by marginal glands in _Prunus munsoniana_ and eglandular in _Prunus angustifolia_. The fruits are larger and wholly plum-like in the newly made species and cherry-like in _Prunus angustifolia_. The stone is very plum-like in _Prunus munsoniana_ but in the older species it might easily be mistaken for the pit of a cherry. The robust form is hardy as far north as Geneva, New York, at least, while the other species cannot be grown much north of Mason and Dixon’s line. Of the varieties which certainly belong to this species by far the greatest number have originated under cultivation. There is herbarium material from uncultivated plants to show that this species is rather common in the northern part of Texas, in eastern Oklahoma and in parts of Missouri. It is a species forming dense thickets in its native habitat, where it is usually found in rather rich soils, with the older central specimens sometimes attaining a height of twenty to twenty-five feet and gradually diminishing in height to the edge of the thicket. When budded and grown in the orchard it forms a well-defined trunk and attains a height of twenty-five feet or more. The branches are little or not at all spinescent, bark of the stem in young specimens reddish or chestnut-brown, and usually rather smooth, becoming scaly and losing its reddish color with age, that of the young twigs usually chestnut-brown. Its natural range, though not yet definitely determined, probably extends from central Tennessee through northern Mississippi, northern Arkansas, central Missouri and southeastern Kansas to the valley of the Little Wichita River in northern Texas.