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: Portugal Laurel

General Information

Prunus lusitanica is an evergreen shrub or a tree usually growing 3 - 8 metres tall but sometimes reaching 20 metres. It is usually wider than it is tall[].
The plant is often grown as an ornamental in gardens, where it can be used as a hedge and a windbreak.

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

W. Europe - southwestern France, Spain, Portugal; N. Africa - Macaronesia, Morocco

Habitat

Disturbed sites, thickets, urban forests; at elevations up to 400 metres[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Shrub
Height	6.00 m
Pollinators	Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Prunus lusitanica is fairly cold-hardy, when dormant it can tolerate temperatures down to about -20°c[].
Succeeds on all soil types[], though it prefers a well-drained moisture-retentive loamy soil[, ]. Prefers some lime in the soil but is likely to become chlorotic if too much lime is present[]. Thrives on chalk according to other reports[, , ]. Succeeds in sun or partial shade though it fruits better in a sunny position[, ].
A very ornamental plant[], there are some named varieties selected for their ornamental value[]. Grows well in a woodland[].
Most members of this genus are shallow-rooted and will produce suckers if the roots are damaged[].
A serious defect of the Portugal laurel is that it is susceptible to Silver Leaf disease (Stereum purpureum)[].
Plants in this genus are notably susceptible to honey fungus[].
The flowers are pleasantly scented[].
Any trimming is best done with secateurs in August[]. Plants are very tolerant of pruning.

Edible Uses

The fruit is probably edible when fully ripe but should not be eaten if it is bitter because this bitterness is caused by the presence of toxic compounds, see the notes above on toxicity[]. The dark purple, ovoid fruit is about 8 - 12mm 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

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 very good plant for a low windbreak[].
The plant tolerates trimming well and so is used as a medium to tall hedge and is also suitable for topiary[, , ].

Other Uses

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

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[, ].
Cuttings of mature wood, early autumn in a sheltered north facing border outdoors[].
Layering in spring.