The rambutan , Nephelium lappaceum) is a medium-sized tropical tree in the family Sapindaceae, and the fruit of this tree. It is native to Indonesia and Southeast Asia, although its precise natural distribution is unknown. It is closely related to several other edible tropical fruits including the Lychee, Longan, and Mamoncillo. It is believed to be native to the Malay Archipelago.[1]. Rambutan in Indonesian or Malay literally means hairy caused by the 'hair' that covers this fruit. In Panama, Costa Rica, and Nicaragua, it is known as mamón chino. There is a second species regularly for sale at Malay markets which is known as "wild" rambutan. It is a little smaller than the usual red variety and is colored yellow.
Rambutan is adapted to warm tropical climates and is sensitive to temperatures below 10° C, and is grown commercially within 15° of the equator. The trees do best on deep soils that are high in organic matter and thrive on hilly terrain as they require good drainage. Rambutan is propagated by grafting, air-layering, and budding; the latter is most common as trees grown from seed often produce sour fruit. Budded trees may fruit after 2-3 years with optimum production occurring after 8-10 years. Trees grown from seed bear after 5-6 years.
The aril is attached to the seed in some commercial cultivars, but "freestone" cultivators are available and in high demand. There is usually a single light brown seed which is high in certain fats and oils (primarily oleic acid and eicosanoic acid) valuable to industry, and used in cooking and the manufacture of soap. Rambutan roots, bark, and leaves have various uses in medicine and in the production of dyes.
Rambutan trees bear twice annually, once in late fall and early winter with a shorter season in late spring and early summer. The fragile nutritious fruit must ripen on the tree, then they are harvested over a four to seven week period. The fresh fruit are easily bruised and have a limited shelf life. An average tree may produce 5,000-6,000 or more fruit (60-70 kg or 130-155 lb per tree). Yields begin at 1.2 tonnes per hectare (0.5 tons/acre) in young orchards and may reach 20 tonnes per hectare (8 tons per acre) on mature trees. In Hawaii, 24 of 38 cultivated hectares (60 of 95 acres) were harvested producing 120 tonnes of fruit in 1997. It has been suggested that yields could be increased via improved orchard management, including pollination, and by planting high yielding compact cultivars.
Most commercial cultivars are hermaphroditic (producing flowers that are female with a small percentage of male flowers); cultivars that produce only functionally female flowers require the presence of male trees. Male trees are seldom found as vegetative selection has favored hermaphroditic clones that produce a high proportion of functionally female flowers and a much lower number of flowers that produce pollen. There are over 3000 greenish-white flowers in male panicles, each with 5-7 anthers and a non-functional ovary. Male flowers have yellow nectaries and 5-7 stamens. There are about 500 greenish-yellow flowers in each hermaphroditic panicle. Each flower has six anthers, usually a bi-lobed stigma, and one ovule in each of its two sections (locules). The flowers are receptive for about one day but may persist if pollinators are excluded.