In the northeastern United States and adjacent Canada, Prunus nigra co-occurs with, and is sometimes confused with, Prunus americana, despite being distinct in both flower and leaf[].
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: Canadian Plum

General Information

Prunus nigra is a moderately thorny, deciduous shrub or a tree with a narrow head of erect branches; it can grow 3 - 9 metres tall. The plant sometimes produces suckers[, ].
The plant is harvested from the wild for local use as a food, medicine and source of materials. It is sometimes cultivated as a fruit crop.

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

Eastern N. America - Manitoba to Nova Scotia south to Iowa, Ohio and Connecticut.

Habitat

Thickets, stream banks and woodland edges[], in alluvial soils of river valleys and on limestone hills[]. Borders of deciduous woods, bottomland forests, roadside thickets; at elevations up to 800 metres[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	9.00 m
Pollinators	Insects
Cultivation Status	Cultivated, Wild

Cultivation Details

Thrives in a well-drained moisture-retentive loamy soil, growing 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[, ].
Sometimes cultivated as a fruit tree in Canada and America, and also in Siberia - where it is valued for its resistance to the harsh climate. There are some named varieties that have been selected for their edible fruit[, ].
This species is closely related to Prunus americana and at times confused with it[].
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[, ]. A succulent flesh[]. It can be eaten out of hand, used in pies, preserves etc, or can be dried for later use[, , , ]. The fruit is small and not very palatable[]. A sour flavour with a thick skin[], though the flavour is improved tremendously if the fruit is harvested after being touched by a few frosts[]. The red, orange or yellowish-red, round to oval fruit is about 15 - 30mm in diameter and contains one large seed[, , ].

Seed - raw or cooked. The seed contains prussic acid and there have been cases recorded of children dying after eating fruits without removing the stones[]. See the notes above on toxicity.

Medicinal

An infusion of the inner bark has been used in the treatment of colds[].
An infusion of the bark has been used to settle the stomach when it will not retain food[].

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:

A bad companion for potatoes, the plum tree harbours aphids that can damage the potatoes[].

Other Uses

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

The inner bark has been used as an astringent colour fixative in dyeing with other plants[].

The wood is close-grained, hard and moderately heavy[, ]. It weighs 43lb per cubic foot[]. The tree is too small to be used commercially[].

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[, ].
Softwood cuttings from strongly growing plants in spring to early summer in a frame[].
Layering in spring.