Winter-buds obtuse, three-lobed at maturity; leaves oblong-ovate, thin and firm, acuminate, long-pointed, two and one-half to three inches long, two-thirds inch broad, unequally cuneate or rounded at the base; margins closely serrate with incurved, calloused or rarely glandular teeth; upper surface glabrous, light green, lower surface paler and pilose; petioles slender, slightly grooved, puberulous, one-half inch long; glands two, large, at the apex of the petiole. Flowers appearing after the leaves; borne in three or four-flowered fascicles on stout pedicels one-half inch long; calyx-tube turbinate; lobes puberulous on the outer surface, with thick tomentum, often tipped with red on the inner surface; petals narrowly obovate, rounded at the apex, narrowing at the base into slender claws, white or tinged with pink; stamens orange, exserted; style glabrous, thickened at the apex into a truncate stigma. Fruit globose, an inch in diameter, deep red with a heavy bloom; skin thick; flesh yellow, juicy, of good flavor; stone flattened, oval, slightly rugose, deeply grooved on the dorsal and ridged on the ventral edge. The history and habitat of Orthosepala are given by Sargent as follows: “The history of this plant as I know it, is briefly this: In June, 1880, Dr. George Engelmann of St. Louis, sent to the Arnold Arboretum a package of seeds marked ‘Prunus, sp. southern Texas.’ Plants were raised from these seeds and in 1888, or earlier, they flowered and produced fruit, which showed that they belonged to a distinct and probably undescribed species. A name, however, was not proposed for it, and in 1888, probably, plants or seeds were sent to Herr Spath, of the Rixdorf Nurseries, near Berlin, where this plum was found in flower by Dr. Emil Koehne, who has described it under the name of _Prunus orthosepala_.” Of the affinity of this species Sargent says: “_Prunus orthosepala_ is a true plum, rather closely related to _Prunus hortulana_, from which it can be distinguished by the smaller number of glands of the petioles, by the eglandular calyx-lobes, the dark colored fruit and smoother stone.” As the writer has seen this plum growing in the Arnold Arboretum, Jamaica Plains, Massachusetts, and the City parks at Rochester, New York, it seems well worth cultivating. Mr. J. W. Kerr writes of it as follows: “I have _P. orthosepala_ fruiting here, and with me its fruit is exceptionally fine in quality, sparingly produced—attributable I believe to the fact that no variety stands near enough to it for proper inter-pollination. The trees are rather dwarfish in habit, close-headed, with fine clean foliage. The fruit is globular in form; size equal to fair specimens of Hawkeye or Wyant; skin a greenish-yellow, almost entirely covered with deep red.”