Canadian Plum

Description

Prunus nigra is a deciduous shrub or small tree growing to 10 metres (33 ft) tall with a trunk up to 25 cm diameter, with a low-branched, dense crown of stiff, rigid, branches. The bark is gray-brown, older layers coming off in thick plates. The branchlets are bright green at first, later become dark brown tinged with red, and spiny. The winter buds are chestnut brown, long-pointed at the tip, up to 8 millimetres (0.31 in) long. The leaves are alternate, simple, oblong-ovate or obovate, 5-12 centimetres (2.0-4.7 in) long and 3-7 centimetres (1.2-2.8 in) broad, wedge-shaped or slightly heart-shaped or rounded at base, doubly crenaulate-serrate, abruptly contracted to a narrow point at the apex, feather-veined, midrib conspicuous; they emerge from the bud convolute, downy, slightly tinged with red, are smooth, becoming bright green above and paler beneath when full grown. The leaf petioles are stout, bearing two large dark glands and early deciduous, lanceolate or three to five-lobed stipules. The flowers are 15-25 millimetres (0.59-0.98 in) diameter, with five rounded petals, white fading to pale pink, with a more or less irregularly notched margin; they are slightly fragrant, borne in three to four-flowered umbels, with short, thick peduncles, and appear before the leaves in mid to late spring. The flower stalks are slender and dark red. The calyx is conic, dark red, five-lobed, the lobes acute, finally reflexed, glandular, smooth on the inner surface, imbricate in bud, ovate, with short claws, imbricate in bud. There are 15-20 stamens, inserted on the calyx tube; filaments thread-like; anthers purplish, introrse, two-celled; cells opening longitudinally; the pistil has a superior ovary in the bottom of calyx tube, one-celled, with two ovules. The fruit is an oblong-oval drupe, 25-30 millimetres (0.98-1.18 in) long with a tough, thick, orange red skin, free from bloom, yellow flesh adherent to the stone; the stone oval, compressed. It matures in late summer or early autumn. The cotyledons are thick and fleshy. The species grows best in alluvial soils. It can easily be confused with the related Prunus americana, differing most obviously in the leaf margins having blunt, gland-tipped teeth, rather than the sharp, glandless teeth of P. americana leaves.