The plums are treated here as comprising a number of subspecies, but this treatment is not universally accepted. The Flora of N. America[], for example, says that distinctions given in the literature between Prunus domestica and Prunus domestica insititia, and which cultivated varieties are derived from each of them, are contradictory and confusing. They treat Prunus domestica as one variable species without designation of infraspecific taxa[].
The plums are treated here as comprising a number of subspecies, but this treatment is not universally accepted. The Flora of N. America[], for example, says that distinctions given in the literature between Prunus domestica and its subspecies, and which cultivated varieties are derived from each of them, are contradictory and confusing. They treat Prunus domestica as one variable species without designation of infraspecific taxa[].
The taxonomic history of Prunus is long and complicated, in part due to the economic value of its fruit crops and also the ease with which some species hybridize. Here, Prunus is circumscribed in its broad sense based on the argument that when viewed on a worldwide scale, the morphologic discontinuities among the segregate genera diminish and they overlap with one another. Included here are species that have at times been placed in the genera Amygdalus, Armeniaca, Cerasus, Laurocerasus, Padus, and Persica.
At the species level, Prunus has been the object of the usual combining and splitting common among taxonomists with different philosophies and opinions. In particular, over-reliance on the indument of various vegetative and floral parts has led to the naming of numerous species and infraspecific taxa. Similarly, too much has been made of fruit colour and palatability in naming taxa of Prunus. It is very likely that, as molecular and genetic data are analyzed and, more importantly, correlated with morphological data, circumscriptions will be redrawn and the number of Prunus species will be reduced[].

Common Name: Plum

General Information

Prunus domestica is a deciduous shrub or a tree usually growing 2 - 6 metres tall, occasionally to 15 metres[, ].
The plum is very widely cultivated, both commercially and in gardens, for its edible fruit. The plant also has a number of other uses, as food, medicine and a source of materials.

Known Hazards

The plant (especially the seed and young shoots) contains cyanogenic glycosides, especially amygdalin and prunasin. When injested, these compounds break down in the digestive tract to release cyanide. Used in small quantities in both traditional and conventional medicine, this exceedingly poisonous compound has been shown to stimulate respiration, improve digestion, and promote a sense of well-being[]. It is also claimed by some to be of benefit in the treatment of cancer - though this claim has been largely refuted.
In larger concentrations, however, cyanide can cause gasping, weakness, excitement, pupil dilation, spasms, convulsions, coma and respiratory failure leading to death[].
The fruits and flowers of most members of this genus generally have low or very low concentrations of this toxin, though the seeds and young shoots can contain much higher levels.
The levels of toxin can be detected by the level of bitterness:- for example sweet tasting almond seeds are a major food crop and are often eaten in quantity, whilst bitter tasting almond seeds are used as a flavouring (in marzipan for example) but are not usually eaten on their own.
In general, it can be considered safe to eat any fruit or seed from species in this genus that either have a sweet flavour or are slightly bitter. Great caution should be taken, however, if the flavour is moderately to very bitter[].

Botanical References

, ,

Range

This species is widely naturalized in temperate regions. It is not known truly wild.

Habitat

Found in hedges in Britain[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	5.00 m
Growth Rate	Medium
Pollinators	Insects
Self-fertile	Yes
Cultivation Status	Cultivated

Cultivation Details

The plum is fairly cold-hardy, able to tolerate temperatures down to around -20°c when dormant. It prefers growing in a continental climate and other regions that have clearly defined seasons - mild winter areas tend to encourage earlier flowering with a greater risk of frost damage to the blossom, whist cool summers will often not ripen the fruit fully.
Requires a well-drained moisture retentive soil[, ] and a sheltered position[]. Succeeds in light shade but fruits better in a sunny position[, ]. Thrives in a loamy soil, doing well on limestone[]. Grows well in heavy clay soils. Prefers some chalk in the soil but it is apt to become chlorotic if too much is present[]. Prefers a pH between 6 and 6.5[].
The plum is widely cultivated for its edible fruit in temperate zones,Tthere are many named varieties able to supply fresh fruits from the middle of summer to early winter[]. Many cultivars are fully self-fertile, though some are partially self-sterile and others require cross-pollination[]. The various varieties are often divided into groups or subspecies, a practice we are following here. The following subspecies are all given a separate entry:-
Prunus domestica domestica. The common plum, with skins of various colours and a typical oval shape, is treated in this entry.
Prunus domestica insititia. Including the damsons and the bullaces, the fruits are usually dark purple, somewhat smaller than the plums and more acid, Bullaces have a more globose shape whilst damsons have the typical oval shap of plums.
Prunus domestica italica. The greengages. A usually green, globose fruit with a very rich flavour.
Prunus domestica syriaca. The mirabelle. The globose fruits are yellow or red in colour and somewhat smaller than a plum.
Where space is at a premium, or at the limits of their climatic range, plums can be grown against a wall. Most cultivars will grow well against a sunny wall, whilst an east facing wall will suit some of the tougher cultivars, but a wall that recieves little direct sunlight is not really suitable[].
This species is probably a hybrid of ancient origin involving Prunus spinosa and Prunus cerasifera, coupled with chromosome doubling[, ].
The cultivated plum does not cross-pollinate with the Japanese plum, Prunis salicina[].
Most members of this genus are shallow-rooted and will produce suckers if the roots are damaged[].
Plants in this genus are notably susceptible to honey fungus[].

Edible Uses

Fruit - raw or cooked[, , , ]. The fruit varies considerably from cultivar to cultivar, but it is generally somewhat mealy, soft and juicy with a delicious flavour ranging from very sweet to acid[]. The more acid fruits are usually only used for cooking purposes[]. The fruit varies widely in colour and size according to cultivar but can be blue-black, green, yellow or red and range from 15 - 80mm long, containing a single large seed[].

Seed - raw or cooked. Do not eat the seed if it is too bitter - see the notes above on toxicity.

An edible gum is obtained from points of damage on the trunk[].

The seed contains about 20% of an edible semi-drying oil[, ]. It has an agreeable almond smell and flavour[].

The flowers are eaten. They are used as a garnish for salads and ice cream or brewed into a tea[].

Medicinal

The dried fruit, known as prunes, is a safe and effective laxative and is also stomachic[, , , ].

The bark is sometimes used as a febrifuge and is styptic[, ].

An infusion of the flowers has been used as a mild purgative for children[].

Although no specific mention has been seen for this species, 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[].

Other Uses

A green dye can be obtained from the leaves[].
A dark grey to green dye can be obtained from the fruit[].
A yellow dye is obtained from the bark[].

A gum obtained from points of damage along the stem can be used as an adhesive[].

The ground up seeds are used cosmetically in the production of face-masks for dry skin[].

A semi-drying oil is obtained from the seed[]. No details of its uses.

The reddish-brown wood is very close-grained, hard, compact. Liable to warp and split. It is used for musical instruments[, ].

Propagation

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. The various cultivars of plum are unlikely to breed true - they will usually produce a range of plants from seed with differing characteristics from their parent,
Cuttings of half-ripe wood with a heel, mid summer in a frame[, ].
Softwood cuttings from strongly growing plants in spring to early summer in a frame[].
Layering in spring.