Japanese Plum
Prunus japonica nakai
Family: Rosaceae
What it is like
Prunus japonica nakai is an evergreen Shrub growing to 0.5 m (1ft 8in). See above for USDA hardiness. It is hardy to UK zone 4. It is in flower in May, and the seeds ripen from July to August. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.
Height (m): 0.5
Where it is found
Open country and roadsides. Sunny mountain slopes at elevations of 100 - 200 metres.
E. Asia - China, Korea, Manchuria.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 3
Fruit - raw or cooked. A sweet agreeable flavour, they make a good pie. A very good size, about 50mm in diameter with one large seed. Seed - raw or cooked. Do not eat the seed if it is too bitter - see the notes above on toxicity.
Seed: includes nuts, cereals, peas and beans.
Medicine
Rating: 3
The kernels are aperient, carminative, demulcent, deobstruent, diuretic, lenitive and ophthalmic. Their use lowers the blood pressure. A decoction is used in the treatment of sluggish colon, constipation, oedema and inadequate elimination of urine. The pits of this sub-species are aphrodisiac for both sexes. The root is used in the treatment of constipation, children's fever, pinworms and teeth ailments. All members of the genus contain amygdalin and prunasin, substances which break down in water to form hydrocyanic acid (cyanide or prussic acid). In small amounts this exceedingly poisonous compound stimulates respiration, improves digestion and gives a sense of well-being.
Aperient: A mild laxative.
Aphrodisiac: Increases the sexual appetite.
Carminative: Reduces flatulence and expels gas from the intestines.
Demulcent: Soothes, lubricates and softens irritated tissues, especially the mucous membranes.
Deobstruent: Clears obstructions from the natural ducts of the body.
Diuretic: Acts on the kidneys, promoting the flow of urine.
Lenitive: Soothing, palliative.
Ophthalmic: Treats eye complaints.
Other
Rating: 1
A green dye can be obtained from the leaves. A dark grey to green dye can be obtained from the fruit.
Dye: Plants that provide dyes.
Food Forest: Plants for Edible Forest Gardens and Food Forests.
How it is grown
Thrives in a well-drained moisture-retentive loamy soil. Prefers some lime in the soil but is likely to become chlorotic if too much lime is present. Succeeds in sun or partial shade though it fruits better in a sunny position. A very ornamental plant, but it is subject to die-back. Plants in this genus are notably susceptible to honey fungus. This sub-species has larger plum-like fruits up to 50mm in diameter. Closely related to P. glandulosa. Most members of this genus are shallow-rooted and will produce suckers if the roots are damaged. For polyculture design as well as the above-ground architecture (form - tree, shrub etc. and size shown above) information on the habit and root pattern is also useful and given here if available. A clumping plant, forming a colony from shoots away from the crown but with a limited spread. The root pattern is flat with shallow roots forming a plate near the soil surface.
Propagating it: Seed - requires 2 - 3 months cold stratification and is best sown in a cold frame as soon as it is ripe. Sow stored seed in a cold frame as early in the year as possible. Protect the seed from mice etc. The seed can be rather slow, sometimes taking 18 months to germinate. Prick out the seedlings into individual pots when they are large enough to handle. Grow them on in a greenhouse or cold frame for their first winter and plant them out in late spring or early summer of the following year. Cuttings of half-ripe wood with a heel, July/August in a frame. Softwood cuttings from strongly growing plants in spring to early summer in a frame. Layering in spring.
Best place to grow: Woodland Garden Sunny Edge; Dappled Shade;
Habit: Shrub
Hardiness: 4-8
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: Semi-shade, no shade
Moisture: Moist
Things to keep in mind
Although no specific mention has been seen for this species, it belongs to a genus where most, if not all members of the genus produce hydrogen cyanide, a poison that gives almonds their characteristic flavour. This toxin is found mainly in the leaves and seed and is readily detected by its bitter taste. It is usually present in too small a quantity to do any harm but any very bitter seed or fruit should not be eaten. In small quantities, hydrogen cyanide has been shown to stimulate respiration and improve digestion, it is also claimed to be of benefit in the treatment of cancer. In excess, however, it can cause respiratory failure and even death.