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: Peach

General Information

Prunus persica is a deciduous tree with a broad and more or less horizontally spreading crown; it can grow 3 - 10 metres tall[, ].
The peach is widely cultivated for its edible fruit in the warm temperate and subtropical zones. In addition to is fruit, the plant provides a range of other foods, medicines and various commodities.

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

E. Asia - China.

Habitat

Not known in a truly wild situation, it is possibly derived in cultivation from Prunus davidiana.

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	6.00 m
Pollinators	Bees
Self-fertile	Yes
Cultivation Status	Cultivated, Ornamental

Cultivation Details

The peach is very hardy when dormant, tolerating temperatures down to about -20°c, but it requires hot summers in order to ripen its fruit and a clear distinction between seasons. In more maritime climates it can be excited into growth during mild spells only to be damaged by late frosts. It is therefore mainly cultivated in Mediterranean, Continental and subtropical climates. In areas where winters are mild, or summers cool, the plant usually requires some form of protection in order to produce a crop - either by placing it by a sunny wall or in a cold greenhouse[, , ]. Hand pollination can improve fruit-set[].
Succeeds in light shade but fruits better in a sunny position[]. Requires a well-drained moisture retentive soil[, ]. Thrives in a loamy soil, doing well on limestone[]. Best not grown in acid soils. Prefers some chalk in the soil but it is apt to become chlorotic if too much is present[]. Prefers a pH in the range 6 to 7[]. Requires shelter from north and north-east winds[] and also from spring frosts[].
Widely cultivated for its edible fruit in warm temperate areas, the subtropics and continental climates, there are many named varieties[]. There are numerous divisions of the varieties according to skin colour etc. Perhaps the most useful from the eaters point of view is whether it is free-stone (the flesh parts easily from the seed) or cling-stone (the flesh adheres to the seed)[, ].
Most cultivars are self-fertile[].
The cultivar 'Rochester' is more likely than most cultivars to succeed outdoors in cooler parts of the temperate zone[].
Double-flowered cultivars are used ornamentally[].
Trees are often grafted onto plum or other rootstocks but are said to be better when grown on their own roots in southern Britain[].
Trees are not generally long-lived[], this is partly because of the need for the tree to produce a constant supply of new wood since most fruit is formed on one-year old wood (though some fruit spurs are formed)[].
Garlic is a good companion for this plant, helping to prevent disease, especially peach leaf curl[, ]. Tansy grown below peach trees helps to keep them healthier[]. Peach leaf curl can also be prevented by protecting the plants from winter and early spring rains, perhaps by covering them in plastic[]. Plants grown or overwintered indoors do not suffer from leaf curl[].
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, cooked or dried for later use[, , , ]. The fruit is often used in ice creams, pies, jams etc[]. When fully ripe, the fruit of the best forms are very juicy with a rich delicious flavour[]. Wild trees in the Himalayas yield about 36.5kg of fruit a year[]. The fruit of the wild form contains about 5.2% sugars, 2% protein, 1.6% ash. Vitamin C content is 2.3mg per 100g[]. The fruit is a good source of vitamin A[]. Fruits of the wild peach are richer in nutrients than the cultivated forms[]. The size and colour of the fruit varies widely between cultivars and the wild form, it can be 40 - 80mm in diameter and contains one large seed[, ].

Flowers - raw or cooked. Added to salads or used as a garnish[]. They can also be brewed into a tea[]. The distilled flowers yield a white liquid which can be used to impart a flavour resembling the seed[].

Seed - raw or cooked. Do not eat if it is too bitter, seed can contain high concentrations of hydrocyanic acid. See the notes above on toxicity.

A semi-drying oil is obtained from the seed[]. Although the report does not mention edibility it can be assumed that it is edible. The seed contains up to 45% oil[].

A gum is obtained from the stem. It can be used for chewing[].

Medicinal

The leaves are astringent, demulcent, diuretic, expectorant, febrifuge, laxative, parasiticide and mildly sedative[, ]. They are used internally in the treatment of gastritis, whooping cough, coughs and bronchitis[]. They also help to relieve vomiting and morning sickness during pregnancy, though the dose must be carefully monitored because of their diuretic action[].
The dried and powdered leaves have sometimes been used to help heal sores and wounds[].
The leaves are harvested in June and July then dried for later use[].

The flowers are diuretic, sedative and vermifuge[, , , , ]. They are used internally in the treatment of constipation and oedema[].

A gum from the stems is alterative, astringent, demulcent and sedative[, , , , ].

The seed is antiasthmatic, antitussive, emollient, haemolytic, laxative and sedative[, , , , ]. It is used internally in the treatment of constipation in the elderly, coughs, asthma and menstrual disorders[].

The bark is demulcent, diuretic, expectorant and sedative[]. It is used internally in the treatment of gastritis, whooping cough, coughs and bronchitis[]. The root bark is used in the treatment of dropsy and jaundice[]. The bark is harvested from young trees in the spring and is dried for later use[].

The seed contains 'laetrile', a substance that has also been called vitamin B17[]. This has been claimed to have a positive effect in the treatment of cancer, but there does not at present seem to be much evidence to support this[]. The pure substance is almost harmless, but on hydrolysis it yields hydrocyanic acid, a very rapidly acting poison - it should thus be treated with caution[]. 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[]. Yellow according to another report[].
A dark grey to green dye can be obtained from the fruit[].

A semi-drying oil is obtained from the seed[]. It is used as a substitute for almond oil in skin creams[].

The bruised leaves, when rubbed within any container, will remove strong odours such as garlic or cloves so long as any grease has first been fully cleaned off[].

A gum obtained from the stem is used as an adhesive[].

The red wood is close and even-grained, hard and scented. An attractive wood with a pretty, silver grain[].

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[]. The stored seed is best given 2 months warm followed by 3 months cold stratification[]. 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, mid summer in a frame[, ]. A very low percentage[].
Softwood cuttings from strongly growing plants in spring to early summer in a frame[].
Layering in spring.