Wild plum is a shrub that propagates itself by root sprouts to form thickets, or it can be a small tree with spreading, more or less hanging, branches.
Leaves are alternate, simple, 2½–4 inches long, 1½–2 inches wide, broadest at or below the middle; margin sharply toothed; upper surface dark green, lower surface paler and net-veined.
Bark is dark brown to reddish, breaking into thin, long, scaly plates, pores horizontal and prominent.
Twigs are slender, smooth, green to orange to reddish-brown; lateral branches spurlike or sometimes thorny; pores circular, raised, minute buds smooth (without hairs).
Flowers April–May, in clusters of 2–5, stalks ¼–¾ inch long, smooth; flowers ¾–1¼ inches broad, white, fragrant; petals 5, broadest at the middle, rounded at the tip, and narrow at the base; stamens about 20.
Fruits July–September, in clusters with 1–5 fruits; fruit usually ¾–1 inch long, globe-shaped, red or sometimes yellow, conspicuously marked with pale dots; skin tough; flesh yellow and juicy, varying in flavor.
Similar species: At least 11 species in genus Prunus have been recorded growing in natural settings in Missouri, and at least 4 of them are called "plums." The rest are cherries, peach, and apricot.
- Chickasaw plum (P. angustifolia) is scattered, mostly south of the Missouri River, in upland prairies, sand prairies, openings in upland forests, pastures, ditches, roadsides, and similar habitats. The leaves are smaller and lance-shaped, the blade usually slightly folded lengthwise and the tip curled down.
- Wild goose plum, or hortulan plum (P. hortulana), is scattered to common nearly statewide, though less common in northwest Missouri. It occurs along stream, pond, and lake banks; edges of prairies and swamps; pastures, fencerows, old homesites, roadsides, and similar habitats. A native multistemmed shrub, it is sometimes cultivated as an ornamental, and cultivars exist. Leaf margin is finely toothed with a gland arising from the very tip of each tooth; the teeth are conspicuous, spreading away from the margin.
- Wild goose plum (P. munsoniana, P. rivularis, or P. hortulana), is a native suckering shrub scattered nearly statewide, except for the extreme northwestern and southeastern parts of the state. It forms dense thickets. It bears red or yellow, white-dotted, ¾-inch-long fruits, with a thin whitish coating. The leaf margins are finely toothed to rounded with a gland on the incurved face; fully grown leaves are more or less folded lengthwise, appearing troughlike.
- Big tree plum, or wild plum (P. mexicana), is scattered to common nearly statewide, growing on banks of streams and rivers, rich upland forests, pond edges, bases and tops of bluffs, glade edges, pastures, fencerows, roadsides, and similar habitats. A native plum, it is sometimes planted as an ornamental or as a wildllife food plant. Its ball-shaped fruits can reach 1½ inches wide; they become red but eventually ripen to grayish blue or grayish lavender with a whitish coating. The lower surface of the leaves is hairy; the leaf stalk is stout and hairy.
- Black cherry, wild cherry, or rum cherry (P. serotina) is scattered to common nearly statewide. This common native tree usually grows 32–50 feet high. Dense, cylindrical, many-flowered flower clusters 3–6 inches long develop after the leaves develop.
- Choke cherry, or eastern choke cherry (P. virginiana), is scattered to common north of the Missouri River, less common in the southern half of the state. A native shrub or small tree, its flowers form in short, dense, cylinderical slusters 3–6 inches long; it bears edible fruits (15–30 in a cluster) used to make jellies and jams.
- Sour cherry (P. cerasus), the cultivated fruit tree that originated in Eurasia, sometimes escapes from cultivation or persists at old home sites.
- Perfumed cherry (P. mahaleb), a native of Eurasia, was introduced as an ornamental, as grafting stock for other cherries, and as a source for cherrywood pipestems. It is scattered in the southern half of the Ozarks, in glades, upland forests, stream and river banks, bluff ledges, and in pastures, fencerows, cemeteries, roadsides, and similar habitats. It can be aggressive, forming thickets and sometimes invading natural areas. Planting it is discouraged. Leaves are egg-shaped to broadly heart-shaped or circular, the top abruptly pointed to blunt.; the upper surface is dark green, shiny, and smooth.
- Peach (and nectarine) (P. persica), the cultivated fruit tree native to Asia, is uncommon and sporadic in Missouri's natural settings. It sometimes occurs in upland forests, stream banks, and old homesites, roadsides, and other disturbed areas. Its flowers are pink or strongly pinkish-tinged.
- Apricot (P. armeniaca), the cultivated fruit tree native to Asia, sometimes escapes from cultivation or persists at old home sites. Its flowers are pink or strongly pinkish-tinged while in bud, but become white at flowering.
Note that several other small trees in the rose family bloom in spring with white, five-petaled flowers:
- Downy serviceberry (Amelanchier arborea) has petals that are bright white, strap-shaped, wavy, with a space between them (not rounded and close together).
- The invasive Callery (or Bradford) pear (Pyrus calleryana) has white petals that are rounded and close together (they touch/overlap at their bases); its flower stamens are not longer than the petals; and the flowers are unpleasant-smelling.
- Apples and crabapples (Malus spp.) have flowers with a slightly pink hue. Their fruits, on maturity, have the seeds surrounded by a papery or leathery "core."