Lansium parasiticum

Lansium parasiticum

The duku or longkong (Lansium parasiticum (Osbeck) Sahni & Bennet) is an arboreal species belonging to the Meliaceae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Plantae,
Magnoliophyta division,
Class Magnoliopsida,
Subclass Rosidae,
Sapindales Order,
Meliaceae family,
Genus Lansium,
L. parasiticum species.
The terms are synonyms:
– Aglaia aquea (Jacq.) Kosterm.;
– Aglaia domestica (Corrêa) Pellegr.;
– Aglaia dookoo Griff.;
– Aglaia intricatoreticulata Kosterm.;
– Aglaia merrillii Elmer;
– Aglaia sepalina (Kosterm.) Kosterm.;
– Aglaia steenisii Kosterm.;
– Amoora racemosa Ridl.;
– Lachanodendron domesticum (Corrêa) Nees;
– Lansium parasiticum (Osbeck) K.C.Sahni & Bennet;
– Melia parasitica Osbeck.

Etymology –
The term Lansium was coined by the French botanist Adrien-Henri de Jussieu in 1830 to honor the German botanist Johann Christian Lange, who was responsible for classifying and describing various plants in the 19th century.
The specific epithet parasiticum comes from the Greek παρασῑτέω parasitéo eat together (composed of the prefix πᾰρἆ- pará- close to, near, together and from σιτέω sitéo feed); however, despite the name suggesting a parasitic plant, this species can grow as an epiphyte in nature, which was once thought to be an indication of parasitism.

Geographic Distribution and Habitat –
Lansium parasiticum is a species whose origin is still the subject of debate among botanists; however, the plant is generally believed to be native to regions of Southeast Asia, especially the islands of Malaysia and Indonesia.
In addition to Malaysia and Indonesia, it has also been introduced and cultivated in other parts of Southeast Asia, such as the Philippines, Thailand, Vietnam and Burma. Trees of this plant can also be found in some regions of India and Papua New Guinea.
Its habitat is that of rainforests and humid and river valleys, including kerengas, where they also grow on calcareous soils at altitudes up to 110 meters.

Description –
Lansium parasiticum is a plant that grows in the form of a tree that can reach 30 meters in height and 75 centimeters in diameter. 30-year-old trees grown from seed and planted at a distance of 8 × 8 meters can have a height of 10 meters and a diameter of 25 cm.
The trunk grows irregularly, with its buttress roots visible above ground. The bark of the tree is grayish in color, with light and dark spots. Its resin is thick and milky in colour.
The leaves are pinnate, compound and odd, with fine hairs and 6 to 9 buds at intervals. The buds are long and elliptical, about 9-21 centimeters by 5-10 centimeters in size. The upper edge is glossy and the leaves themselves have pointed bases and tips. The stems of the buds measure from 5 to 12 millimeters.
The flowers are borne in inflorescences which grow and hang from thick branches or the trunk; clusters can be numbered up to 5 in one place. They are often branched at the base, measure 10 to 30 centimeters and have short hair. The flowers are small, with short stems and have two sexes. The sheath has the shape of a five-lobed cup and is greenish-yellow in colour. The crown is egg-shaped and hard, measuring 2 to 3 millimeters by 4 to 5 millimeters. There is one stamen, measuring 2mm in length. The top of the stamen is round. The pistil is short and thick.
The fruit can be elliptical, ovoid or round, measuring 2 to 7 centimeters by 1.5 to 5 centimeters in size. The fruits closely resemble small potatoes and are borne in grape-like clusters. The largest fruits are of the variety known as duku. It is covered in a fine yellow hair which gives it a slightly fuzzy appearance. The thickness of the skin varies according to the variety, from 2 millimeters to about 6 millimetres. With the husks removed, the fruit resembles peeled garlic, with half a dozen white, translucent lobes, some of which contain a flat, bitter-tasting seed.
The seeds are covered with a dense light white aril which has a sweet and sour taste. The taste has been likened to a combination of grapes and grapefruit and is considered excellent by most. The sweet and juicy pulp contains sucrose, fructose and glucose. For consumption, cultivars with small or underdeveloped seeds and dense aril are preferred.

Cultivation –
Lansium parasiticum is an evergreen fruit tree that grows primarily in humid tropical climates where it is grown for its edible fruit.
It is a tree of tropical lowland forests and even in its native range it cannot be cultivated at altitudes above 650 – 750 metres.
The temperature range for growth is reported as 12 to 40°C with the optimum being 20 to 35°C.
It needs a humid atmosphere, lots of humidity and does not tolerate long dry seasons. The annual rainfall range for growth is referred to as 1,000 – 3,000 mm with the optimum between 1,400 – 2,200 mm. It can tolerate a dry season if shade and humidity are adequate. In Java, for example, the tree grows in areas with 6 to 12 rainy months if there is more than 100mm of rain per month.
Young plants require some shade but older plants can tolerate full sun, although some shade is preferable.
From a pedological point of view, it grows best in slightly acidic soil, rich in humus, well drained and fertile and does not like heavy soils. It prefers a pH between 6 and 6.5, tolerating between 5.5 and 7.5.
It usually bears fruit once a year. This period can vary from area to area, but flowering generally occurs after the onset of the rainy season and fruit production about four months later.
One of the main obstacles to its cultivation seems to be its slow growth; apparently it takes 12 years or more to grow from seed. However, air layering from mature trees, as well as grafting, is said to work well and produce much faster.
Trees do not always grow and fruit well outside of Asia. There are successful commercial orchards in Suriname, although the plant has been unsuccessful in Honduras. It can be grown in Trinidad and Puerto Rico.
In the Philippines, a productive tree produces an average of 1,000 fruits per year, where it is grown in partial shade interspersed with coconut plants.
In regards to propagation these plants are commonly grown from seeds, which have a short viability and need to be planted within 1-2 days after removal from the fruit.
Sowing is done in a shaded position in a nursery seedbed. Germination can begin after 10 days, with around 90% germinating within a month. Multiple seedlings, resulting from polyembryony, are quite common.
The propagation can also take place by asexual way with various types of grafts: slit, lateral and flanking which give good results. The shoot must be mature but not old, 6.5-9 cm long, 6-20 mm thick, and is joined to rootstocks of the same diameter about 6.5-10 cm above the ground.
Within this species there are numerous cultivars. Overall, there are two main groups of cultivars, those named duku and those named langsat. There are also mixed duku-langsat varieties.
Those called duku generally have a large canopy, thick with bright green leaves, with short clusters of few fruits. The individual fruits are large, generally round, with a rather thick skin which does not release sap during cooking. The seeds are small, with thick flesh, sweet smell and sweet and sour taste.
The variant commonly known as langsat generally has thinner trees, with a less dense canopy made up of dark green leaves and stiff branches. The clusters are longer and each cluster contains 15 to 25 large egg-shaped fruits. The skin is thin and releases a white sap when cooked. The pulp is watery and has a sweet and sour taste.

Customs and Traditions –
Lansium parasiticum is a plant known by various names depending on where it grows spontaneously or is cultivated. It is known as langsat (Malayo), lansones (Tagalo). lanzonés (Philippine Spanish), lansa, langseh, langsep, lanzon, lanzone, lansone, longkong (Thai), duku, kokosan (Indonesian), lòn bon, gadu guda (Tamil), and bòn bon (Vietnamese). In Spanish it takes the name of lanzón and in English of longkong.
The major producers of L. parasiticum are Indonesia, Thailand, the Philippines and Malaysia. Production is mainly for domestic consumption, although some is exported to Singapore, Hong Kong and Kuwait.
This plant is mainly grown for its fruit, which can be eaten raw. The fruit can also be bottled in syrup.
The fruits as well as raw can be eaten cooked. These in the raw state are juicy, aromatic and sub-acidic.
Each fruit contains 5 or 6 segments of aromatic, white, translucent, juicy pulp, with 1 – 3 relatively large and very bitter seeds.
The seeds can sometimes adhere very tightly to the pulp and can thus impart their bitterness to the fruit.
However, the peel is easily removed and the pulp is commonly eaten as it is or served as a dessert and can be cooked in various ways.
It is best to soak varieties with a lot of latex in boiling water to get rid of the gummyness before peeling.
The peeled, seedless or deseeded fruits are canned in syrup or sometimes candied.
While refreshing, the fruits have one of the lowest vitamin C contents of any fruit grown in Malaysia.
This plant is also used in the medicinal field.
The resin is non-toxic and is administered to stop diarrhea and intestinal spasms.
The dried pericarp is used in the treatment of diarrhea and intestinal spasms, malaria and other fevers. The active ingredient in the pericarp appears to be a resin.
The pulverized seed is used as a febrifuge and vermifuge.
The bark is smeared on scorpion stings.
An astringent decoction of the bark is used as a cure for dysentery and malaria.
The leaves can be combined with the bark in the preparation of the decoction.
The juice of the leaves is used as eye drops to dispel inflammation.
Other uses include agroforestry; the tree is in fact used in the reforestation of hilly areas.
Among other uses it is reported that the peel is rich in tannin; the fresh one contains 0.2% of a light yellow volatile oil; from the dried peel a dark semi-liquid oleoresin is obtained, composed of 0.17% volatile oil and 22% resin.
The dried husk is burned in Java, the aromatic smoke serves as a mosquito repellent and as incense in sick rooms.
Wood tar, derived from distillation, is used to blacken teeth.
The wood is light brown, medium-hard, fine-grained, tenacious, elastic and resistant, weighing 840 kg/mc. It is used in Java for house posts, beams, tool handles and small tools.
Among the known dangers, it is reported that an arrow poison is extracted from the peel of the fruit and the bark of the tree. Both possess a toxic property; this substance, when injected, stops the heartbeat in frogs. The seed contains a tiny amount of an as yet unidentified alkaloid and two bitter and toxic principles.

Method of Preparation –
Lansium parasiticum is a fruit tree native to Southeast Asia. Its fruits are small, spherical and have a thin yellow or light brown skin. The inner pulp is translucent, juicy and has a sweet-tart taste.
The fruits are usually eaten fresh. The fruit pulp can be separated from the peel and eaten directly. The fruits are generally sweet and slightly tart, similar to a combination of tastes between pineapple and orange. They are considered a delicacy in many parts of Southeast Asia and are widely available in local markets during the harvest season.
In some regions, they are also used to make juices, ice creams, jams and other food products. The pulp can be squeezed to obtain a sweet and refreshing juice, which can be eaten on its own or used as an ingredient in various preparations.
However, it is important to note that some people can be allergic. Therefore, if you are sensitive to food allergies or experience adverse reactions after consuming the fruit, it is advisable to consult a doctor.

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. (ed.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and experiences with medicinal herbs, Ennsthaler Editore.

Photo source:
– https://upload.wikimedia.org/wikipedia/commons/0/0f/Lanzones.jpg

Attention: The pharmaceutical applications and alimurgical uses are indicated for informational purposes only, they do not in any way represent a medical prescription; we therefore decline all responsibility for their use for curative, aesthetic or food purposes.