Prunus padus
Prunus pumila
bird cherry, European bird cherry, hackberry
cerisier des sables, dwarf sand plum, sand cherry
with terminal end buds, glabrous or puberulent.
with terminal end buds, glabrous or sparsely to densely puberulent (var. susquehanae).
deciduous;
petiole 8–17 mm, glabrous or puberulent on adaxial surface or both surfaces, glandular distally, glands 1–4;
blade elliptic to obovate, 5–10(–13) × 2.5–4.5(–7) cm, base obtuse to rounded or subcordate, margins serrate, teeth ascending to spreading, sharp, eglandular, apex acuminate to abruptly so, lateral veins 10–18 per side, raised abaxially, surfaces glabrous or abaxial hairy in vein axils or along midribs.
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.
15–50-flowered, racemes;
central axes 45–150 mm, leafy at bases.
2–5-flowered, umbellate fascicles.
3–17 mm, glabrous.
3–19 mm, glabrous.
blooming after leaf emergence;
hypanthium cupulate, 2–2.5 mm, glabrous externally;
sepals broadly spreading to reflexed, oblong-ovate, 1.2–2 mm (lengths greater than widths), margins glandular-toothed, surfaces glabrous;
petals white, obovate to suborbiculate, (5–)6–9 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.
black, globose, 6–8 mm, glabrous;
hypanthium deciduous, leaving discs at bases of drupes;
mesocarps fleshy;
stones subglobose, not flattened, rugulose.
dark purple to nearly black, subglobose or broadly ellipsoid, 6–12 mm, glabrous;
mesocarps fleshy;
stones subglobose, ovoid, or fusiform, not flattened.
= 32.
Prunus padus
Prunus pumila
Prunus padus is cultivated in North America as an ornamental prized for its long, showy racemes of white flowers and its cold hardiness. Its value in the upper Midwest is often compromised by fungal infection causing black knot disease.
Prunus padus is difficult to distinguish from P. virginiana var. demissa, at least from herbarium material. Induments of hypanthium interior have been widely used in keys to separate the two: hairy in P. padus versus glabrous in P. virginiana. As noted by E. G. Voss (1972–1996, vol. 2), many of the specimens of P. virginiana have a pubescent hypanthium, especially basally. This is true throughout the range of P. virginiana, and also for some specimens of P. serotina. The hypanthia of P. padus are more hairy than those of P. virginiana. The petals of P. padus are longer than those of eastern chokecherry (P. virginiana var. virginiana), making it possible to distinguish flowering specimens from east of the Rocky Mountains. The petals are only slightly longer, on average, than those of P. virginiana var. demissa. Petals of P. padus are also a bit narrower and more elliptic. Shape of sepals may prove useful: 1.2–2 mm with lengths greater than widths in P. padus versus 0.7–1.4 mm with lengths equal to widths in P. virginiana var. demissa. In fruit, the difference between rugulose stones of P. padus and smooth stones of P. virginiana is subtle, perhaps too subtle for those unfamiliar with the range in variation of pit surfaces among these taxa.
(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 |
BC
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