Prunus umbellata
Prunus emarginata
Alleghany plum, flatwood plum, hog or flatwoods or Allegheny plum, hog plum, sloe
bitter cherry, Oregon cherry
with axillary end buds, usually glabrous, sometimes hairy.
with terminal end buds, glabrous or hairy.
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.
deciduous;
petiole 3–12 mm, glabrous or hairy, usually eglandular, rarely glandular distally, glands discoid;
blade elliptic, oblong, oblanceolate, or obovate, (1.5–)2–6(–8) × 1–3(–4.2) cm, base cuneate, margins crenate to serrate, teeth blunt, glandular, apex usually rounded to obtuse, rarely acute, surfaces glabrous or downy, abaxial often hairier.
2–4(–6)-flowered, umbellate fascicles.
(3–)6–12-flowered, corymbs or racemes;
central axes (5–)9–30 mm.
5–22 mm, usually glabrous, sometimes hairy.
3–12(–18) mm (subtended by leafy bracts), glabrous or hairy.
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.
blooming at leaf emergence;
hypanthium obconic, 2.5–3 mm, glabrous or hairy externally;
sepals reflexed, oblong, 1.5–2 mm, margins entire, surfaces usually glabrous, sometimes hairy abaxially;
petals white, elliptic to obovate, 3–8 mm;
ovaries glabrous or with scattered hairs.
red, yellow, dark blue, or nearly black, glaucous, globose, 10–15 mm, glabrous;
mesocarps fleshy;
stones ovoid, slightly to ± flattened.
bright red, globose to ovoid, 7–14 mm, glabrous;
mesocarps fleshy;
stones ellipsoid, not flattened.
Prunus umbellata
Prunus emarginata
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.)
H. J. Scoggan (1978–1979, part 3) included Prunus emarginata within P. pensylvanica. Given that much of the problem of separating P. emarginata from P. pensylvanica arises from intermediate plants found in British Columbia and western Montana where the ranges of the two species meet, this makes some sense from a Canadian perspective. When viewed from a continental perspective, P. emarginata normally does not look much like P. pensylvanica (see notes on their differences under 10. P. pensylvanica).
Individuals of Prunus emarginata vary considerably in their habit, size and shape of leaves, and indument on branchlets, inflorescences, and leaves. Many segregate species have been described based on this variation. Most often, western botanists have recognized one species with two varieties based on habit or indument; those characters are not well correlated. Some keys use habit to separate the varieties (var. emarginata, a shrub, versus var. mollis, a tree, commonly used in Pacific Northwest floras); others have used indument (var. emarginata, glabrous, versus var. mollis, hairy, more commonly used in floras of the arid West). On the mountain slopes in the more arid portions of its range, P. emarginata is a thicket-forming shrub to about 6 m with the leaves expanding to no more than 50 mm; in the moister, milder climates of coastal Oregon to British Columbia, as well as the interior wetbelt of northern Idaho, northwestern Montana, and adjacent British Columbia, the plants are trees to 15 m with larger leaves expanding to 80 mm. Hairy plants occur throughout the range of P. emarginata, and glabrous plants are found from British Columbia to Arizona, generally not west of the Cascades.
Hybrids between Prunus emarginata and naturalized P. avium (P. ×pugetensis Jacobson & Zika) have been reported from the lowlands of western British Columbia, Oregon, and Washington.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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