Agroforestree Database

Local names:
 Burmese (duku,langsak), English (Langsat,duku), Filipino (lanzone,lanzon,lansones,lansone,buahan), Indonesian (duku,kokosan,langsat), Malay (langseh,langsep,lansa), Thai (duku,longkong,langsat), Vietnamese (bòn-bon)

Lansium domesticum is an erect, short-trunked, slender or spreading, reaching 10-15 m in height, with red-brown or yellow-brown, furrowed bark.

Leaves pinnate, 22.5-50 cm long, with 5-7 alternate leaflets, obovate or elliptic-oblong, pointed at both ends, 7-20 cm long, slightly leathery, dark-green and glossy on the upper surface, paler and dull beneath, and with prominent midrib.

Flowers small, white or pale-yellow, fleshy, mostly bisexual, borne in simple or branched racemes which may be solitary or in hairy clusters on the trunk and oldest branches, at first standing erect and finally pendant, 10-30 cm long.

Fruits borne 2-30 in a cluster, oval, ovoid-oblong or nearly round, 2.5-5 cm in diameter, and have light greyish-yellow to pale brownish or pink, velvety skin, leathery, thin or thick, and containing milky latex. There are 5 or 6 segments of aromatic, white, translucent, juicy flesh (arils), acid to subacid in flavour.

Seeds, which adhere more or less to the flesh, are usually present in 1 to 3 of the segments. They are green, relatively large, 2-2.5 cm long and 1.25-2 cm wide, very bitter, and sometimes, if the flesh clings tightly to the seed, it may acquire some of its bitterness. 

There are two distinct botanical varieties; var. pubescens, the typical wild langsat which is a rather slender, open tree with hairy branchlets and nearly round, thick-skinned fruits having much milky latex and var. domesticum, called the duku, doekoe, or dookoo, which is a more robust tree, broad-topped and densely foliaged with conspicuously-veined leaflets; the fruits, borne few to a cluster, are oblong-ovoid or ellipsoid, with thin, brownish skin, only faintly aromatic and containing little or no milky latex. The former is often referred to as the wild type but both varieties are cultivated and show considerable range of form, size and quality. There are desirable types in both groups. Some small fruits are completely seedless and fairly sweet.

Ecology

The langsat is ultra-tropical. It is a tree of tropical lowland forest and is damaged by frost. Even in its native territory it cannot be grown at an altitude over 650-750 m. It needs a humid atmosphere, plenty of moisture and will not tolerate long dry seasons. Some shade is beneficial especially during the early years. In Java the tree grows in areas with 6-12 wet months if there is over 100 mm rainfall monthly.

Native range
Cambodia, China, Indonesia, Malaysia, Philippines

Tree management

The trees are spaced 8-10 m apart in orchards. Generally, the langsat is casually grown in dooryards and on roadsides and receives no cultural attention. Regular irrigation results in better fruit size and heavier crops. Thrice-yearly applications of a 6-6-6 fertilizer formula with added minor elements result in good growth, productivity and high quality fruits even in an adverse environment. In the Philippines, a productive tree averages 1 000 fruits per year, where it is grown in half shade interplanted with coconut. Seedlings will bear in 12-20 years.

Seeds are recalcitrant and viability can only be maintained for about 5 weeks if kept moist. Viability is totally lost in 8 days unless fresh seeds are stored in polyethylene bags at 4-6 deg C where they will remain viable for 14 days.

The langsat is ultra-tropical. It is a tree of tropical lowland forest and is damaged by frost. Even in its native territory it cannot be grown at an altitude over 650-750 m. It needs a humid atmosphere, plenty of moisture and will not tolerate long dry seasons. Some shade is beneficial especially during the early years. In Java the tree grows in areas with 6-12 wet months if there is over 100 mm rainfall monthly.

Langsats are commonly grown from seeds, which must be planted within 1-2 days after removal from the fruit. Cleft-, side- and approach-grafting give good results. The budwood should be mature but not old, 6.5-9 cm long, 6-20 mm thick, and it is joined to rootstock of the same diameter about 6.5-10 cm above the soil.

Poison: An arrow poison is made from the fruit peel and the bark of the tree. Both possess a toxic property, lansium acid, which, on injection, arrests heartbeat in frogs. The seed contains a minute amount of an unnamed alkaloid and 2 bitter, toxic principles. The dried peel is burned in Java, the aromatic smoke serving as a mosquito repellent and as incense in the rooms of sick people.

The tree is used in reforestation of hilly areas.

 The peel of the langsat is easily removed and the flesh is commonly eaten out-of-hand or served as dessert, and may be cooked in various ways. Varieties with much latex are best dipped into boiling water to eliminate the gumminess before peeling. The peeled, seedless or seeded fruits are canned in syrup or sometimes candied.

Timber: The wood is light-brown, medium-hard, fine-grained, tough, elastic and durable, weighing 840 kg/ cu m. It is utilized in Java for house posts, rafters, tool handles and small utensils. Wood tar, derived by distillation, is employed to blacken the teeth.

Tannin or dyestuff: The peel is reportedly high in tannin.

Medicine: The resin is non-toxic and administered to halt diarrhoea and intestinal spasms. The pulverized seed is employed as a febrifuge and vermifuge. The bark is poulticed on scorpion stings. An astringent bark decoction is taken as a treatment for dysentery and malaria. Leaves may be combined with the bark in preparing the decoction. The leaf juice is used as eye-drops to dispel inflammation.

Gum or resin: The seed contains a minute amount of an unnamed alkaloid and 1% of an alcohol-soluble resin. The fresh peel contains a brown resin and reducing acids, from the dried peel, a dark, semi-liquid oleoresin composed of 0.17 % volatile oil and 22%

In the Philippines they are frequently planted around the edges of coconut plantations.

Essential oil: The fresh peel contains 0.2% of a light-yellow volatile oil, from the dried peel, a dark, semi-liquid oleoresin composed of 0.17 % volatile oil and 22% resin is obtained.