The various species of American plums, including Prunus americana, will commonly hybridize if their ranges overlap producing.individual specimens with intermediate characteristics. Prunus americana and Prunus americana intergrade in Missouri, Arkansas, and neighboring states and it has been suggested that the species should be combined. The Flora of N. America[] however, has chosen to maintain them as distinct.
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: American Plum

General Information

Prunus americana is a moderately thorny, deciduous shrub or a tree with a broad, spreading crown; it can grow 1.5 - 10 metres tall. The bole usually divides low down. The plant produces suckers freely, often developing into a thicket of growth in the wild[, , ].
The tree is harvested from the wild for local use as a food, medicine and source of materials. It is often cultivated as a fruit crop in N. America, and is sometimes grown as an ornamental.
Although Prunus americana is recorded as threatened in parts of its range, it is a very widely distributed species with a stable native population overall. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

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

N. America - Saskatchewan to Quebec and New Brunswick, south to Oregon, Utah, New Mexico, Louisiana and Florida

Habitat

Rich soils in mixed deciduous woodland, by streams, on the borders of swamps and in hedgerows[, , ]. Thickets, moist soil, roadsides, fence rows, margins of woods, stream banks; at elevations from 10 - 2,100 metres[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	6.00 m
Growth Rate	Medium
Pollinators	Insects
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Prunus americana is probably hardy to as low as -50°c when fully dormant[].
Thrives in a well-drained moisture-retentive loamy soil, doing well on limestone[, ]. 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[, ]. This species grows in medium to coarse textured soils that are acidic to mildly alkaline, preferring woodland habitats, scrublands and occasionally prairies[].
A fast-growing but short-lived tree in the wild[], it is cultivated for its edible fruit in N. America, where there are many named varieties[, , ]. It flowers well in Britain but rarely fruits well here[].
The flowers have a faint and rather unpleasant odour[].
The tree has been hybridized with several other species, especially Prunus salicina, to produce superior cultivars[].
Most members of this genus are shallow-rooted and will produce suckers if the roots are damaged[].
The branches are brittle[].
Plants in this genus are notably susceptible to honey fungus[].

Edible Uses

Fruit - raw, cooked in pies etc or used in preserves[, , , , ]. The yellow flesh is succulent and juicy, though it is rather acid with a tough, astringent skin[, , , ]. The best forms are pulpy and pleasant tasting[, ]. The fruit is best cooked[], and it can also be dried for later use[]. The red, orange or yellowish, subglobose fruit is 15 - 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.

Medicinal

A tea made from the scraped inner bark is used as a wash to treat various skin problems and as a mouth wash to treat sores[]. A poultice of the inner bark is disinfectant and is used as a treatment on cuts and wounds[].
The bark is astringent, diuretic and pectoral[]. It has been used to make a cough syrup[]. An infusion has been used in the treatment of diarrhoea, kidney and bladder complaints[].

A gum obtained from the trunk is used for pharmaceutical purposes[].

An infusion of the twigs has been used in the treatment of asthma[].

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[].

Agroforestry Uses:

Trees often grow wild along streams, where their roots tend to prevent soil erosion[].
The tree is sometimes planted in windbreaks[].

Other Uses

A green dye can be obtained from the leaves[].
A dark grey to green dye can be obtained from the fruit[].
A red dye can be obtained from the roots[].

This species is widely used as a rootstock for cultivated plums and also the apricot (Prunus armeniaca) in North America[, ].

Prunus americana is a secondary genetic relative of the Peach (Prunus persica) and Japanese Plum (Prunus salicina), a tertiary genetic relative of the Plum (Prunus domestica). It has the potential for use as a gene donor for crop improvement[].

The tough, elastic twigs can be bound into bundles and used as brooms for sweeping the floor[].

Wood - heavy, hard, close-grained, strong[]. It weighs 45lb per cubic foot[]. Of no commercial value because the trunk is too small[].

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.
Cuttings of half-ripe wood with a heel, mid summer in a frame. Difficult, if not impossible.
Softwood cuttings from strongly growing plants in spring to early summer in a frame. Difficult, it not impossible.
Suckers in late winter.