A small deciduous tree, sometimes up to 20 ft high, but often a shrub a few feet high; branches erect, rigid, glabrous except when quite young, ultimately almost black, the spur-like growths sometimes terminating in a spine. Leaves ovate or oval-lanceolate, pointed, finely and sharply toothed, 2 to 31⁄2 in. long, 3⁄4 to 11⁄4 in. wide, downy on the midrib beneath; stalk 1⁄3 in. long, downy, without glands. Flowers 1⁄2 in. across, produced in April in stalkless umbel-like clusters of two to five, each flower on a slender stalk 1⁄4 to 1⁄2 in. long; petals rather dull white, turning pink with age; calyx funnel-shaped at the base, with ovate-oblong, blunt lobes, downy. Fruits globose or slightly elongated, 1⁄2 to $ in. in diameter, reddish purple, covered with blue bloom.
Native of the Allegheny Mts in Pennsylvania and W. Virginia, where its fruits are known as sloes, and used for preserving, etc. It does not appear to have been recognised in the United States as a distinct species until 1877, when it was named as above. First introduced in 1892 from the Arnold Arboretum to Kew, where for a time it grew and flowered very well, but did not fruit. This tree, however, has since died. It is allied to P. americana, but differs in its blue fruits.