Dimocarpus longan Lour., Fl. Coch. (1790)

Latin for the local Chinese name long-yen, which means dragon eye.

Synonyms
Euphoria cinerea (Turcz.) Radlk.
Euphoria gracilis Radlk.
Euphoria longan (Lour.) Steud.
Euphoria longana Lam.
Euphoria malaiensis (Griff.) Radlk.
Euphoria malaiensis forma genuina Radlk.
Euphoria microcarpa Radlk.
Euphoria verruculosa Salisb.
Linkeng Rumph.
Nephelium longan (Lour.) Hook.f.
Nephelium longana (Lam.) Cambess.
Nephelium long-yan Blume
Nephelium malaiensis Griff.
Pometia curtisii King
Sapindus cinereus Turcz.

Description
Tree, up to 40 m tall and 1 m trunk diameter, sometimes buttressed, exceptionally a scandent shrub; branches terete with 5 faint grooves, sometimes warty lenticellate, rather densely ferruginous tomentose. Leaves 2-4(-6)-jugate, axial parts mostly densely hairy; petiole 1-20 cm, petiolules 0.5-35 mm long; leaflets elliptical, 3-45 cm x 1.5-20 cm, 1-5 times longer than wide, chartaceous to coriaceous, above often tomentose in basal part of midrib, beneath thinly tufted-tomentose mainly on midrib and nerves. Inflorescences usually terminal, 8-40 cm long, densely tufted-tomentose; cymules (1-)3-5-flowered; pedicels 1-4 mm; bracts patent, 1.5-5 mm long; flowers yellow-brown; calyx lobes 2-5 mm x 1-3 mm; petals 5, 1.5-6 mm x 0.6-2 mm, densely woolly to glabrous; stamens (6-)8(-10), filament 1-6 mm. Fruit drupaceous, 1-3 cm in diameter, lobe(s) broad-ellipsoid to globular, smooth to warty or sometimes up to 1 cm aculeate, sometimes granular, glabrescent, yellow-brown. Seed globular with shining blackish-brown testa; seed enveloped by a thin fleshy, translucent white arilloid.

Ecology
In undisturbed to slightly disturbed (open sites) mixed dipterocarp and sub-montane forests up to 1300 m altitude. Usually on hillsides and ridges. On sandy soils, but also on limestone. In secondary forests usually present as a pre-disturbance remnant or planted. Longan is a subtropical tree that grows well in the tropics but requires a prominent change of seasons for satisfactory flowering. A short (2-3 months) but cool (mean temperature 1522 degrees C) winter season brings out a prolific bloom; in this respect longan is less demanding and more predictable than lychee. From fruit set onwards high temperatures do not hamper development, but nights should not be warmer than 20-25 degrees C. Ample soil moisture is needed from fruit set until maturity; suitable annual precipitation is about 15002000 mm. Longan thrives on rich sandy loams, it does well on oolitic limestone; moderately acid sandy soils are more marginal and on organic muck soils flowering is deficient, probably because shoot growth continues for too long. In northern Thailand longan orchards are often situated on the lighter soils along former river courses, a ribbon of trees winding between the sawahs. The roots grow down 2-4 m to the water table. The 'mata kucing' thrives in the humid tropical lowlands near sea level, within about 10 degrees from the equator. The trees occur mainly in the substage or understorey in primary or sometimes secondary forests. Rainfall ranges from 2500 mm to more than 4000 mm per year associated with a mean air temperature of 25-30 degrees C and a relative humidity of 65-95%. In Sarawak, the trees grow on alluvial soil, often on river banks. In other areas the trees grow on a wider range of soil types. A pH range of 4.5-6.5 is common in this region.

Uses
The wood is used for pipes, bearings, rifle butts, weaving stands and general construction. The fruits are edible and sold on local markets. Longans as well as the minor fruits of the species are mainly eaten fresh. There are substantial canning industries for longan in Thailand, China and Taiwan. Large fruits are used, preferably those with small seeds. Fruit can be canned in its own juice with little or no sugar, due to the high level of soluble solids. Canned longans retain their individual flavour better than do rambutan or lychee. Longans can be preserved dry, either intact or after removal of the pericarp. The dried flesh is black, leathery and smoky in flavour and is used mainly to prepare a refreshing drink. A liqueur is made by macerating the longan flesh in alcohol. The seeds are used as a shampoo, like soapberries (Sapindus saponaria L.), because of their saponin content. Both the seed and the fruit flesh of longan have several medicinal uses. The leaves, which contain quercetin and quercitrin, and flowers are sold in Chinese herb markets. The red, hard longan timber and the fairly hard, light brown to yellow 'mata kucing' timber are useful, but rarely available. In eastern Thailand it is grown as an ornamental.

Distribution
From Sri Lanka, India and southern China to New Guinea. Whereas some authors limit the area of origin to the mountain chain from Burma through southern China, others extend it to south-west India and Sri Lanka, including the lowlands. The crop is mainly grown in south China, Taiwan and north Thailand with small acreages elsewhere in Indo-China as well as Queensland (Australia) and Florida (United States) and scattered trees at higher elevations in South-East Asia.

Local names
Borneo: Bambo, Buku, Dopar, Ihau, Longan, Mahau, Mata kuching, Mata kuchin puteh, Rupai, Takuhis.
Burma: kyet mouk.
Cambodia: mien.
English: longan.
French: Longanier, oeil de dragon.
Indonesia, Malaysia: lengkeng, buku, ihau (Kalimantan), medaru (Sumatra).
Laos: lam nhai, nam nhai.
Malaysia: mata kucing (Peninsular Malaysia and Sabah), isau, sau, kakus (Sarawak).
Thailand: lamyai pa, lamyai khruer, lamyai tao.
Vietnam: nhan.