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Dimocarpus longan Lour. 1790
pronounced: dim-oh-KAR-puss LONG-gan
(Sapindaceae – the soapberry or lychee family)
common names: Longan, Dragon’s Eye
Dimocarpus is from the Greek, δις (dis), twice and καρπος (karpos), fruit, referring to the 2-lobed pistil; longan is from the Chinese, and means ‘dragon’s eye’, the fruits of the tree being supposed to resemble them.
This is a handsome, erect, fast-growing evergreen tree with a round, many-branched crown, usually growing 9 – 14 m high, but capable of reaching heights of 25 m or more. It is a native of eastern Asia and the Philippines, where it is usually found in the understorey of primary forests in humid mountainous regions. The photographs are of a tree planted in the exotic fruits garden at Magnetic Island State School.
The trunk can be up to about 80 cm in diameter, with corky bark, The branches are long and thick, typically drooping.
The inflorescences are panicles at the end of the branches, 10 – 45 cm long, and widely branched. The individual flowers are small, have 5 – 6 sepals, and brownish yellow petals. Each flower has a 2-lobed pistil and 8 stamens. There are 3 flower types distributed along the panicle: staminate, pistillate and hermaphrodite, flowering in progression.
The fruits hang in drooping clusters; they are spherical, and about 2.5 cm in diameter. The surface is smooth to warty, and granular to the touch. The peel is tan-coloured, thin, and leathery with tiny hairs. The flesh is translucent; the seed is large and black, with a circular white spot at the base, giving the appearance of an eyeball. The flesh has a musky, sweet taste, rather like that of the lychee, although it is a drier sweetness, with a touch of sour.
Apart from being eaten fresh and raw, the fruit is often used in Asian soups, snacks, desserts, and sweet-and-sour foods. It can be either fresh or dried, or sometimes canned in syrup. Dried longan is often used in Chinese cuisine, where it is believed to have an effect on relaxation.
Longan is used in traditional systems of medicine. The flesh of the fruit is used as a stomachic, febrifuge and vermifuge, and is regarded as an antidote to poison. A decoction of the dried flesh is taken as a tonic. The seeds are administered to counteract heavy sweating, and the pulverized kernel is used as a styptic. In Vietnam, the ‘eye’ of the longan seed is pressed against snakebites to absorb the venom. Despite the fact that this is ineffective, it is still so used today.
The seeds, because of their saponin content, are used as a shampoo. Both the seeds and the rinds of the fruits are burnt for fuel.
The timber is useful, but not readily available. The heartwood is reddish brown, and is not differentiated from the lighter-coloured sapwood. The wood is strong, tough, very hard, difficult to split. It is highly durable, and dries easily but slowly with little or no degradation. It is used for posts, for making agricultural implements, furniture, textile weaving stands and rifle butts, but is not highly valued for fuel.
Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.
The photograph of fruits is from the US Department of Agriculture, via Wikimedia Commons, and is used temporarily until the local tree fruits
Photographed in Nelly Bay 2018
Page last updated 18th May 2018