Prunus spinosa
Prunus emarginata
blackthorn, blackthorn plum, sloe, sloe cherry
bitter cherry, Oregon cherry
with axillary end buds, hairy.
with terminal end buds, glabrous or hairy.
deciduous;
petiole 4–7 mm, hairy, eglandular;
blade elliptic to obovate, 1.5–4 × 1–2.2 cm, base obtuse to rounded, margins crenulate-serrulate, teeth blunt, often glandular, apex acute to obtuse, abaxial surface hairy (especially along midribs and veins), adaxial glabrate.
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.
usually solitary flowers, sometimes 2-flowered fascicles.
(3–)6–12-flowered, corymbs or racemes;
central axes (5–)9–30 mm.
0.5–5(–8) mm, usually glabrous, rarely hairy.
3–12(–18) mm (subtended by leafy bracts), glabrous or hairy.
blooming before leaf emergence;
hypanthium cupulate, 1.5–2.5 mm, glabrous externally;
sepals spreading, oblong, 1.5–2.5 mm, margins glandular-toothed, surfaces glabrous or adaxially hairy at bases;
petals white, elliptic, 4–8 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.
bluish black, globose, 10–15 mm, glabrous;
mesocarps fleshy;
stones subglobose, ± flattened.
bright red, globose to ovoid, 7–14 mm, glabrous;
mesocarps fleshy;
stones ellipsoid, not flattened.
= 32.
Prunus spinosa
Prunus emarginata
As past flora writers (C. L. Hitchcock et al. 1955–1969; E. G. Voss 1972–1996) have noted, the distinctions between Prunus spinosa and P. domestica are not clear. Some researchers consider the hexaploid P. domestica to have been derived from the tetraploid P. spinosa, often in a scenario involving hybridization with P. cerasifera. It should not be surprising that some of the characters used in keys to separate these three taxa (spininess, indument, leaf size, pedicel length, numbers of flowers per bud) are subject to variation within each species and overlap among the species.
(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.)
- Local floras:
BC, 
OR, 
WA - Local Web sites:
Flora NW, 
Go Botany, 
MI Flora, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
- Local floras: BC,
CA, OR, WA - Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria, Turner Photog.
- WildflowerSearch
- iNaturalist (observations)
- USDA Plants Database
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
