Prunus salicina

Prunus salicina

The Chinese plum or Japanese plum (Prunus salicina Lindl., 1830) is a tree species belonging to the Rosaceae family.

Systematics –
Domain Eukaryota,
Kingdom Plantae,
Suborder Tracheobionta,
Superdivision Spermatophyta,
Division Magnoliophyta,
Class Magnoliopsida,
Subclass Rosidae,
Order Rosales,
Family Rosaceae,
Subfamily Amygdaloideae,
Tribe Amygdaleae,
Genus Prunus,
Species P. salicina.
The following terms are synonymous:
– Cerasus salicina (Lindl.) Loudon;
– Cerasus triflora Wall. ex Steud.;
– Prunus botan André;
– Prunus botan hort. ex Chow;
– Prunus gymnodonta Koehne;
– Prunus ichangana C.K.Schneid.;
– Prunus maru L.H. Bailey;
– Prunus masu Koehne;
– Prunus salicina var. angustifolia Nakai;
– Prunus salicina var. columnaris (Uyeki) Uyeki;
– Prunus triflora var. columnaris Uyeki;
– Prunus salicina var. Y.He & J.Y.Zhang consortium;
– Prunus salicina var. pilosa Nakai;
– Prunus salicina var. subspontaneous Makino;
– Prunus salicina var. typical Nakai;
– Prunus staminata Hand.-Mazz.;
– Prunus thibetica Franch.;
– Prunus triflora Roxb.;
– Prunus triflora f. Koehne glomerata;
– Prunus triflora var. latifolia Cardot;
– Prunus triflora var. pubescens Cardot;
– Prunus triflora var. spinifera Koehne;
– Prunus trifolia Roxb.
The following varieties are accepted:
– Prunus salicina var. pubipes (Koehne) L.H. Bailey;
– Prunus salicina var. salicina.

Etymology –
The term Prunus derives from the Ancient Greek proúnē, a term used to indicate plum. The specific epithet salicina, however, derives from Latin and means “willow-like.” This refers primarily to the shape of the leaves: narrow, elongated, and pointed, reminiscent of those of some willow species.
The common name “Japanese plum” can, however, cause some confusion. Prunus salicina is in fact a different species from Prunus mume, also often called Chinese or Japanese plum, and from Prunus japonica. Even the latter, despite its seemingly similar scientific name, is a distinct species.
The species was botanically described by John Lindley in the 19th century and has a rather complex taxonomic history, as is often the case with the Prunus genus, where some species are difficult to distinguish and can also easily hybridize.

Geographic Distribution and Habitat –
Prunus salicina is native to East Asia. Notes indicate its natural range primarily in China, Taiwan, Myanmar, Laos, and Vietnam. Its main center of origin and domestication is identified in southwestern China, particularly in the Yangtze River basin. Some wild populations are still present in the Chinese provinces of Shaanxi and Gansu, among others.
Over time, the plant has been introduced and cultivated in numerous other regions. Japan played a key role in its agricultural history: here, ancient Chinese forms were cultivated and selected, giving rise to varieties that were later introduced to other countries. In the second half of the 19th century, they arrived in the United States, where they were further improved through numerous selection and hybridization programs. Today, the Japanese plum is cultivated not only in China, Japan, and Korea, but also in the United States, Australia, Europe, and several Latin American countries.
In nature, Prunus salicina grows primarily in open woodland environments. It can be found in sparse forests, at the edges of woodlands, in scrublands, along mountain trails, and near valley streams. The species grows at altitudes ranging approximately from 200 to 2,600 meters.
It is a typical plant of relatively warm temperate environments. It flowers early and requires fairly favorable climatic conditions to complete its growing cycle. This characteristic, very useful for producing early fruit, can, however, pose a problem in areas where late frosts are frequent.
The species also has important relationships with soil fungi through mycorrhizae, associations that can promote plant development. In China, it has also been studied for its potential use in the restoration of certain degraded and erosion-prone lands, particularly in karst areas. The results, however, are mixed: its rapid growth can also increase soil nutrient consumption.
Despite the spread of cultivation and the various threats affecting East Asian forests, the wild species is currently listed by the IUCN as Least Concern, and its populations are believed to be stable.

Description –
Prunus salicina is a deciduous tree, meaning it loses its leaves during the cold season. It generally reaches a height of 6 to 12 meters, although size can vary depending on environmental conditions and the variety grown. The branches are reddish-brown or purple in color, while young shoots can take on yellowish or reddish hues.
The leaves are easily recognizable by their elongated shape. They generally measure between 6 and 12 centimeters in length and 2.5 to 5 centimeters in width. They are green and glossy on the upper surface and have a serrated edge. The shape can vary quite a bit, but is generally oblong or elliptical, with a wedge-shaped base and a pointed tip. The presence of these narrow, elongated leaves is the origin, as we have seen, of the name salicina.
Flowering occurs in early spring, generally before the new leaves have fully emerged. The flowers are white, about 2 centimeters in diameter, and consist of five petals. They typically appear in small clusters, often with three flowers. Early flowering is very important for fruit production, but exposes the flowers to the risk of damage from spring frosts.
The fruit is a drupe, a fleshy fruit containing a single woody stone. Prunus salicina plums are generally quite large, reaching up to 7 centimeters in size in horticultural varieties. The skin can be yellow, red, green, or purple and often has a thin whitish coating, called bloom. The shape can be spherical, oval, or slightly conical. The flesh is generally yellowish or pinkish-yellow, very juicy, and, when fully ripe, can be eaten fresh.
Compared to the European plum (Prunus domestica), the fruit of the Japanese plum is generally appreciated for its larger size, brighter colors, texture, aroma, and flavor. It is precisely this characteristic that has favored its widespread use on the fresh fruit market.
Ripening occurs during the summer, typically between July and August, although the exact period varies depending on the cultivar and growing area.
Nutritionally, the fruit contains a very high percentage of water, generally between 80 and 90%, as well as carbohydrates, simple sugars, a small amount of protein, and fiber. It also contains various phenolic compounds and anthocyanins, substances associated with antioxidant properties. However, values ​​can vary significantly between different cultivars.

Cultivation –
Prunus salicina is now one of the main plum species cultivated worldwide. China is the leading producer, followed by the United States, Mexico, Italy, Spain, Pakistan, Korea, Australia, Chile, France, South Africa, and Argentina. In many of these countries, production is primarily for the fresh fruit market.
The history of modern cultivation is particularly interesting. Ancient Asian varieties generally produced smaller fruits. After their introduction to the United States in the second half of the 19th century, major breeding programs were launched. One of the key figures was Luther Burbank, who created numerous crosses between Prunus salicina and other plum species. These programs resulted in cultivars that have become famous worldwide, including ‘Beauty’, ‘Formosa’, ‘Santa Rosa’, ‘Shiro’, and ‘Wickson’.
The ‘Santa Rosa’ cultivar, in particular, is still well-known and cultivated in numerous countries. Other important cultivars include ‘Shiro,’ characterized by yellow fruit; ‘Methley,’ particularly productive; ‘Early Golden,’ ripening early; and several modern varieties bred to produce larger, disease-resistant, or better-storage fruits.
To achieve good yields, it’s important to consider pollination. Most cultivars are self-incompatible, meaning a plant is generally unable to pollinate itself effectively. For this reason, two or more compatible varieties with overlapping flowering periods are often grown together in orchards. However, some self-fertile or self-compatible cultivars exist.
The Japanese plum prefers a warm temperate climate, with summers warm enough to allow for good ripening. It is fairly hardy to winter cold and can tolerate temperatures around -15°C, but its early flowering makes it sensitive to late frosts. For this reason, the earliest varieties must be grown in relatively sheltered locations.
Regarding soil, the plant grows well in deep, well-drained soils that retain a certain amount of moisture, preferably clay-loam or silty-loam. It can grow in both sun and partial shade, but good sun exposure favors fruit production. Excessive lime content can cause chlorosis.
Propagation can be done by seed, although modern fruit growing generally favors techniques that preserve the cultivar’s characteristics. The seed requires a cold stratification period of about two to three months and can germinate slowly, sometimes even after several months. Propagation by cuttings and layering are also possible.
Various rootstocks are used in cultivation, including cherry plum (Prunus cerasifera), Marianna plum, and Murcia plum. Almond, peach, and other compatible stone fruit trees can also be used under certain conditions.
An important aspect concerns fruit preservation. Ripe plums are quite perishable and can only be stored for a few days at room temperature. Refrigeration extends their shelf life, while under controlled conditions, around 0°C and with a relative humidity of 90–95%, some cultivars can be stored for several weeks.
Like many other fruit trees, Japanese plums are susceptible to diseases. Among the most important are some viruses, such as plum pox virus and Prunus necrotic ringspot virus, as well as diseases caused by phytoplasmas. In particular, European stone-fruit yellows can cause yellowing of the leaves, curling, early fruit drop, and branch dieback.

Uses and Traditions –
The primary use of Prunus salicina is, of course, food. Unlike the European plum, which is often used for processing and especially drying, Prunus salicina is grown primarily for fresh consumption. Its plums are prized for their large size, juicy flesh, and bright colors.
In China, in addition to being consumed fresh, the fruit is processed into various traditional preparations. One of the most characteristic involves preserving or candying the plum with sugar, salt, and licorice. In some regions, wild fruits are also collected directly from the woods and consumed as a wild food source.
In Japan, the fruit is more limited in availability than Prunus mume, the famous ume. However, it is also used there, especially when preserved or still partially unripe. In some areas, it is consumed during summer festivals as a preserved fruit covered in mizuame, a type of thick, sweet syrup.
Another traditional use is in the preparation of alcoholic beverages. Plums can be used to produce wine, liqueurs, and flavored beverages. Various spices, including cinnamon, cloves, ginger, nutmeg, coriander, and black pepper, can also be used to make plum wine. The ‘Santa Rosa’ cultivar is considered particularly suitable for producing high-quality wine.
Semi-ripe fruits are also used to make sumomo-shu, a traditional Japanese plum-flavored liqueur. In Taiwan, the fruit is also documented in alcoholic preparations made from Prunus mume and oolong tea.
The Japanese plum has also been used in traditional Chinese medicine. Traditionally, the fruit has been associated with digestive effects, the ability to quench thirst, and other therapeutic uses. Modern research has focused primarily on the presence of phenolic compounds and the fruit’s antioxidant properties. However, it is important to distinguish between traditional uses and the properties actually demonstrated by clinical research: available studies, for example, do not support the fruit’s potential as a cancer cure.
Finally, there are some lesser-known uses. A green dye can be obtained from the leaves, while the fruit can produce a dye ranging from dark gray to green. The species is also important for the genetic improvement of plum trees and other stone fruits, thanks to its genetic richness and the potential for using some of its traits in breeding programs.

Preparation or Use –
The simplest and most common way to use Prunus salicina is to eat the fruit fresh, when it is fully ripe. The peel is edible, and the flesh, generally sweet and very juicy, is eaten directly after removing the stone.
Plums can also be cooked and used to make desserts, cakes, preserves, jams, and jellies. This allows you to utilize a portion of the fruit that cannot be consumed quickly as fresh fruit.
Another option is drying, a traditional technique that significantly extends the fruit’s shelf life. Plums can also be processed into preserved or candied products. In China, for example, traditional preparations include sugar, salt, and licorice.
The fruit can also be used to make wine and liqueurs. Ripe fruit is generally used for wine, while partially unripe plums are used for some liqueurs, such as sumomo-shu. Flavoring can involve the addition of various spices and herbs.
In Japanese tradition, the fruit can be preserved and flavored, or covered in mizuame and sold during certain summer festivals. In this case, the plum’s value is not only as a food, but also as an integral part of local gastronomic and festive traditions.
An important precaution concerns the pit. As with many other species of the Prunus genus, the seeds and some vegetative parts of the plant contain cyanogenic glycosides, including amygdalin and prunasin. These substances can release cyanogenic compounds, including hydrocyanic acid. For this reason, the pit should not be consumed, especially if cracked or crushed. The leaves and young shoots should also not be used as normal food.
Ultimately, the part of the plant primarily intended for consumption is the ripe fruit without the pit. The wide variety of ways in which plums can be consumed—fresh, cooked, preserved, dried, candied, or made into beverages—largely explains the agricultural and cultural success of this species.

Guido Bissanti

Sources
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (eds.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora d’Italia, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and Experiences with Medicinal Herbs, Ennsthaler Editore.

Photo source:
– https://www.gbif.org/occurrence/search?view-GALLERY&taxonKey-4N976&entity-o_5198286613

Warning: The pharmaceutical applications and dietary uses are provided for informational purposes only and do not in any way constitute medical prescriptions. We therefore decline any responsibility for their use for curative, aesthetic, or nutritional purposes.