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[
Amygdalus mira (Koehne) Ricker
Amygdalus mira (Koehne) T.T.Yu & L.T.Lu
Persica mira (Koehne) Kovalev & Kostina
Common Name: Smoothpit Peach
Prunus mira is a deciduous tree with spreading branches; it can grow up to 10 metres tall[
An almond with a fleshy fruit, the plant is cultivated in China and also harvested from the wild for its edible fruit and seeds[
In Tibet this species is threatened by deforestation for agriculture and pastureland, and overexploitation from unregulated harvesting. Further direct threats to this species across the rest of its range remain unknown. However, there are several known threats to the forests of China in general, including illegal logging and legal deforestation due to increasing population pressures and urbanization. Air and water pollution are also having a detrimental effect on China's forests. The plant is classified as 'Data Deficient' in the IUCN Red List of Threatened Species(2013)[
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[
E. Asia - China (Sichuan, Yunnan, Xizang)
Open hillsides; at elevations up to 4,000 metres in the Himalayas[
]. Slopes in mixed forests, mountain valleys and ravines at elevations from 2,000 - 4,000 metres in western China[
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Succeeds in sun or partial shade though it fruits better in a sunny position[
]. Thrives in a well-drained moisture-retentive loamy soil, doing well in limestone[
]. Prefers some lime in the soil but is likely to become chlorotic if too much lime is present[
]. This species has grown very well in an alkaline soil with 30cm of loam above chalk[
This species is cultivated for its fruit and seeds in China. It is often uncertain whether collections are wild, cultivated, or escaped from cultivation[
]. The plants fruit freely in Britain[
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[
Fruit - raw or cooked[
]. A bitter flavour[
]. Like a freestone peach but with a small ovoid smooth seed[
]. The subglobose fruit is about 30mm in diameter and contains one large seed[
Seed - raw or cooked[
]. Do not eat the seed if it is too bitter - see the notes above on toxicity.
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[
A green dye can be obtained from the leaves[
A dark grey to green dye can be obtained from the fruit[
Prunus mira is a primary genetic relative of the Peach (Prunus persica) and a secondary genetic relative of the Almond (Prunus dulcis), and so it has the potential for use as a gene donor for crop improvement[
As rootstock for the cultivated peach it can induce dwarfed growth[
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, mid summer in a frame[
Softwood cuttings from strongly growing plants in spring to early summer in a frame[
Layering in spring.