Prunus padus
Prunus umbellata
bird cherry, European bird cherry, hackberry
Alleghany plum, flatwood plum, hog or flatwoods or Allegheny plum, hog plum, sloe
with terminal end buds, glabrous or puberulent.
with axillary end buds, usually glabrous, sometimes hairy.
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 3–14 mm, hairy, usually eglandular, sometimes hairy only adaxially, glandular distally, glands 1–3, discoid;
blade usually elliptic to broadly elliptic, sometimes oblanceolate to obovate, 3.5–8 × 1.5–4 cm, base usually cuneate to obtuse, rarely rounded, margins finely, usually singly serrulate, sometimes doubly serrate, teeth sharp, usually eglandular, sometimes glandular, glands blackish, spheric, apex usually acute, sometimes short-acuminate, abaxial surface hairy to glabrate, adaxial glabrous.
15–50-flowered, racemes;
central axes 45–150 mm, leafy at bases.
2–4(–6)-flowered, umbellate fascicles.
3–17 mm, glabrous.
5–22 mm, usually glabrous, sometimes hairy.
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 or at leaf emergence;
hypanthium tubular (often tubular-urceolate when dried), 2–4 mm, glabrous or hairy externally;
sepals erect-spreading, ovate-oblong, 1.5–2.5 mm, margins usually entire, sometimes 2-fid at apices, ciliate, abaxial surface hairy or glabrous, adaxial hairy;
petals white, sometimes turning pink, obovate to suborbiculate, 3–8 mm;
ovaries glabrous.
black, globose, 6–8 mm, glabrous;
hypanthium deciduous, leaving discs at bases of drupes;
mesocarps fleshy;
stones subglobose, not flattened, rugulose.
red, yellow, dark blue, or nearly black, glaucous, globose, 10–15 mm, glabrous;
mesocarps fleshy;
stones ovoid, slightly to ± flattened.
= 32.
Prunus padus
Prunus umbellata
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.)
Traditionally treated as distinct species, Prunus alleghaniensis from the Appalachians and P. umbellata from southeastern United States are very similar; their ranges overlap in North Carolina and Tennessee. Similar plants disjunct in Michigan have been called P. alleghaniensis var. davisii. Morphological characters (petiole length, shape of blade along with its base and apex, degree of suckering) that have been used to separate these taxa vary as much within each taxon as among them. Since they can be separated only by geographic distribution, they are combined in this treatment.
Some specimens from Connecticut with hairy twigs, petioles, pedicels, and hypanthia were determined as Prunus alleghaniensis by Eames a century ago and do seem to fit within P. umbellata. Other Connecticut specimens determined as P. alleghaniensis (for example, Eames 121, MICH) with scattered glandular teeth on the sepals seem better placed in P. americana. The sole specimen known from Massachusetts (Pease 10,005, NEBC) has singly serrate leaves evenly tapered at both ends as in P. umbellata, but larger petals and reflexed sepals like those of P. americana.
In the southeastern United States, hairy forms have been called Prunus injucunda or P. mitis; the degree of indument on the twigs, petioles, leaf surfaces, pedicels, hypanthia, and sepals is subject to much trivial variation throughout the southeast, the Appalachians, and in Michigan.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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