Common Name: Longan

General Information

Dimocarpus longan is a handsome, erect, fast-growing, evergreen tree with a many-branched crown, usually growing 9 - 14 metres tall but able to reach a height of 25 metres or more. The bole can be 1 metre in diameter, sometimes with buttresses[, ].
The fruit is highly valued in the Orient, especially in China, both as a food and as a medicine[]. It is often sold in local markets and is also sometimes exported. The tree is often cultivated in tropical, subtropical and frost-free warm temperate areas for its edible fruit[].

Known Hazards

None known

Botanical References

,

Range

E. Asia - China, India, Sri Lanka, Myanmar, Thailand, Cambodia, Laos, Vietnam, Malaysia, Indonesia, Philippines.

Habitat

Humid mountain woodlands[]. Usually found in the understorey of primary forests, sometimes in secondary formations[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	12.00 m
Growth Rate	Fast
Self-fertile	Yes
Cultivation Status	Cultivated, Wild

Cultivation Details

Whilst the longan succeeds in warm temperate to tropical areas, it requires a distinct cool season of up to 3 months with virtually no frost to initiate blooming[] and so does not fruit well at low elevations in the tropics[]. Flowering is poor after a warm winter and in areas with no clear cool season[]. It needs chilling temperatures of about 7 - 12°c, or a 2 - 3 month period with temperatures about 15 - 22°c and a short dry period in order to stimulate flowering[]. From fruit set onwards high temperatures do not hamper development, but nights should not be warmer than 20 - 25°c[]. The temperature range for growth is reported to be 7 - 36°c with the optimum between 18 - 30°c[]. Ample soil moisture is needed from fruit set until maturity; suitable annual precipitation is about 1,500 - 2,000mm[]. The annual rainfall range for growth is reported to be 800 - 3,000mm[].
Prefers some shade from the strongest sun[]. Succeeds on most fertile soils so long as there is an abundance of moisture[]. Prefers a pH in the range 5.5 - 6, but can tolerate 5 - 8[].
Seedling trees take 7 - 10 years to commence bearing fruit, whilst vegetatively propagated trees can fruit in 3 - 5 years[].
Full-grown trees given sufficient room may yield 180 - 225 kg of fruit in good years. Larger trees have larger crops but if the trees become too tall harvesting is too difficult, and they should be topped[]. A serious problem with the longan is its irregular bearing - often one good year is followed by 1 or 2 poor years[].
There are some named varieties[, ].
Trees are usually self-fertile[].

Edible Uses

Fruit - raw or cooked. The mucilaginous flesh is whitish, translucent and somewhat sweet, though not as flavoursome as the related lychee(Litchi chinensis)[, ]. It is delicious eaten raw and can also be dried, preserved in syrup, cooked in sweet and sour dishes or in soups[]. The globose fruits are 12 - 25mm in diameter, with a thin, brittle, yellow-brown to light reddish-brown rind[].
Longans are much eaten fresh, out-of-hand, but some have maintained that the fruit is improved by cooking[]. In China, the majority are canned in syrup or dried. For drying, the fruits are first heated to shrink the flesh and facilitate peeling of the rind. Then the seeds are removed and the flesh dried over a slow fire[]. The dried product is black, leathery and smoky in flavour and is mainly used to prepare an infusion drunk for refreshment[].

Medicinal

The flesh of the fruit is administered as a stomachic, febrifuge and vermifuge, and is regarded as an antidote for poison. A decoction of the dried flesh is taken as a tonic and treatment for insomnia and neurasthenic neurosis[].

In both North and South Vietnam, the 'eye' of the longan seed is pressed against a snakebite in the belief that it will absorb the venom[].

Leaves and flowers are sold in Chinese herb markets but are not a part of ancient traditional medicine. The leaves contain quercetin and quercitrin[].

The seeds are administered to counteract heavy sweating and the pulverized kernel, which contains saponin, tannin and fat, serves as a styptic[].

Other Uses

The seeds, because of their saponin content, are used like soapberries (Sapindus saponaria L.) for shampooing the hair[].

The seeds and the rind are burnt for fuel[].

The heartwood is reddish brown it is not clearly demarcated from the lighter-coloured sapwood. The wood is strong, tough, very hard, difficult to split, highly durable, easily but slowly drying with little or no degradation. It is used for posts, agricultural implements, furniture, construction, shuttle pipes, bearings, textile weaving stands and rifle butts[, , ].
The wood is not highly valued for fuel[].

Propagation

Most longan trees are grown from seed. After drying in the shade for 4 days, the seed should be planted without delay, but no more than 2 cm deep, otherwise they may send up more than one sprout[]. Germination takes place within 7 - 10 days[]. The seedlings are transplanted to shaded nursery rows the following spring and set in the field 2 - 3 years later during winter dormancy[].
Air layering. Air-layers bear fruit within 2 - 3 years from planting[].
Grafting

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