Prunus spinosa
Prunus myrtifolia
blackthorn, blackthorn plum, sloe, sloe cherry
West Indian cherry, West Indies or myrtle laurel cherry
with axillary end buds, hairy.
with terminal end buds, glabrous.
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.
persistent;
petiole 8–16 mm, glabrous, eglandular;
blade elliptic to broadly elliptic, 4–10 × 2–4.5(–6.5) cm, base cuneate, obtuse, or nearly rounded, margins undulate, entire, apex acute to acuminate, apicula obtuse, surfaces glabrous, abaxial glandular, glands 2, proximal, flat, circular to oval.
usually solitary flowers, sometimes 2-flowered fascicles.
12–30-flowered, racemes;
central axes (11–)20–50 mm, leafless at bases.
0.5–5(–8) mm, usually glabrous, rarely hairy.
(2–)3–6 mm, glabrous.
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.
usually bisexual, proximal sometimes staminate, blooming before leaf emergence;
hypanthium cupulate, 1.5–2.5 mm, glabrous externally;
sepals spreading, semicircular, 0.5–0.8 mm, margins usually entire, occassionally with a glandular tooth, surfaces glabrous;
petals white, obovate to suborbiculate, 1.5 mm;
ovaries glabrous.
bluish black, globose, 10–15 mm, glabrous;
mesocarps fleshy;
stones subglobose, ± flattened.
purple-black, globose to ± ovoid, 8–12 mm, glabrous;
mesocarps leathery;
stones subglobose, not flattened.
= 32.
Prunus spinosa
Prunus myrtifolia
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.)
Prunus myrtifolia, when compared with P. caroliniana, has flowers more widely spaced on longer rachises and pedicels, and flowers in the winter rather than the spring. The leaves of P. myrtifolia are broader on average, and their apices are blunt at the tip; the fruits are more rounded at the apices with smaller apicula.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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