Prunus nigra
Prunus pumila
black plum, Canada plum, Canadian plum, prunier noir
cerisier des sables, dwarf sand plum, sand cherry
with axillary end buds, usually glabrous, rarely hairy.
with terminal end buds, glabrous or sparsely to densely puberulent (var. susquehanae).
deciduous;
petiole 8–22 mm, glabrate with hairs adaxially, sometimes glandular distally, glands 1–3, discoid;
blade broadly elliptic to obovate, (5–)7–11 × 3–6.5 cm, base obtuse to rounded or subcordate, margins doubly crenate-serrate, teeth blunt, glandular, apex abruptly acuminate, abaxial surface hairy along midribs and major veins, adaxial glabrous.
deciduous;
petiole 2–10(–13) mm, glabrous or hairy only when young, sometimes glandular distally or on margins at bases of blades, glands 1–2;
blade elliptic, oblanceolate, or obovate, 2.5–8 × 0.8–3 cm, base obtuse, cuneate, or long-attenuate, margins crenulate-serrulate to serrate in distal 1/2–2/3, teeth sharp or blunt, callus-tipped, sometimes glandular, apex short-acuminate to rounded, surfaces glabrous.
2–4-flowered, umbellate fascicles.
2–5-flowered, umbellate fascicles.
7–20 mm, usually glabrous, rarely hairy.
3–19 mm, glabrous.
blooming before or at leaf emergence;
hypanthium red-tinged, obconic, 3–4(–5) mm, usually glabrous, rarely hairy externally;
sepals broadly spreading to reflexed, ovate, 2–4(–5) mm, margins glandular-toothed, abaxial surface usually glabrous, rarely sparsely hairy, adaxial glabrous or hairy;
petals white, often fading to pink, suborbiculate to oblong-obovate, 8–13 mm;
ovaries glabrous.
blooming before leaf emergence;
hypanthium campanulate, 1.7–3 mm, glabrous externally;
sepals erect to reflexed, semicircular, 1.3–2.8 mm, margins glandular-toothed, surfaces glabrous;
petals white, oblanceolate, oblong, or suborbiculate, 3–9 mm;
ovaries glabrous.
red, orange, or yellowish, barely glaucous, globose to ellipsoid, 15–30 mm, glabrous;
mesocarps fleshy;
stones ovoid-ellipsoid, strongly flattened.
dark purple to nearly black, subglobose or broadly ellipsoid, 6–12 mm, glabrous;
mesocarps fleshy;
stones subglobose, ovoid, or fusiform, not flattened.
= 16.
Prunus nigra
Prunus pumila
In the northeastern United States and adjacent Canada, Prunus nigra co-occurs with, and is sometimes confused with, P. americana, despite being distinct in both flower and leaf. The red-tinged hypanthia and sepals of P. nigra give the entire inflorescence a pinkish coloration even when the petals are pure white, and the sepals bear obvious glandular teeth along their margins; in P. americana the hypanthia and sepals are green and the sepals bear relatively few glandular teeth or are eglandular. The leaf marginal teeth of P. nigra are rounded and bear glands at their tips or have callus scars where the glands fell off; those of P. americana are acute and eglandular; some may have a callused tip.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 4 (4 in the flora).
Opinion has varied as to whether Prunus pumila is best treated as one variable species (for example, H. Groh and H. A. Senn 1940; H. A. Gleason 1952; J. R. Rohrer 2000) or as two, three, or four separate species (for example, W. F. Wight 1915; M. L. Fernald 1923b; P. M. Catling et al. 1999). The plants vary in stem posture, twig indument, leaf shape, fruit size and taste, pit size and shape, and ecologic preference. Even though the morphologic characters show almost continuous variation, four varieties are recognized here based largely on differences in ecologic habitat and geographic range.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Twigs densely puberulent (10× magnification); leaf apices usually obtuse, sometimes acute or rounded, blade lengths ca. 2.6 times widths; sandy pine-oak woods or barrens with open canopy, or adjacent fields and lakeshores. | var. susquehanae |
1. Twigs usually glabrous, sometimes sparsely puberulent; leaf apices short-acuminate, acute, or obtuse, blade lengths ca. 2.9–3.7 times widths; usually in open habitats | → 2 |
2. Stems prostrate to decumbent; leaf blades oblanceolate, lengths ca. 3.7 times widths; stones ovoid to fusiform, 4.5–5 mm wide. | var. depressa |
2. Stems usually erect-ascending, sometimes decumbent or sprawling; leaf blades elliptic, obovate, or oblanceolate, lengths ca. 2.9–3.3 times widths; stones subglobose to ovoid, 5–7 mm wide | → 3 |
3. Leaf blades usually oblanceolate, lengths ca. 3.3 times widths; shores of the Great Lakes on sandy, gravelly, or rocky beaches, dunes, and interdunal flats. | var. pumila |
3. Leaf blades elliptic, oblanceolate, or obovate, lengths ca. 2.9 times widths; sandy prairies, oak savannas, rock outcrops. | var. besseyi |
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