DISTRIBUTION
Lansium duranum was originally native to the Malaysian peninsula and known locally as Langsat.
Agriculturally, the tree is grown throughout the entire Southeast asian region, ranging from Southern India to the Philippines for its fruit. In the Philippines, where it is locally referred to as the lanzones or langsa, the plant is grown mostly on the southern parts of the island of Luzon, especially in Paete, Laguna, due to the species' narrow range of conditions favorable to its survival. It is also found in abundance on Northern Mindanao particularly in places as Butuan, Cagayan de Oro, and Camiguin. The Camiguin variety is especially sweet and succulent.
In Indonesia, Langsat is very popular fruit in West Kalimantan (Pontianak, Indonesia) and South Sumatra (also called 'Duku'). In Sarawak, northern Borneo, the name Duku is reserved for the larger-sized varieties of Langsat, near the size of golf balls, claimed sweeter and with less sap in the peel. A variety called Dokong exported to mainland Malaysia from Thailand grows tighter in the clusters, giving it a faceted shape, and is preferred by many over the standard Langsat.
Within mainland Asia, the tree is cultivated in Thailand (Thai: ลางสาด, langsat), Cambodia, Vietnam and India, as well as its native Malaysia. Outside the region, it has also been successfully transplanted and introduced to Hawaii and Surinam. It grows well in the wetter areas (120 inches/3 meters or more annual rainfall) of Costa Rica, where it is still very rare, having been introduced decades ago by the United Fruit Company. A major hindrance to its acceptance seems to be that it is very slow in bearing, said to take 12 years from seed. However, air layering from mature trees, as well as grafting, are said to work well and produce much faster.
Fruit
Fruits are ovoid, roundish orbs around five centimeters in diameter, usually found in clusters of two to thirty fruits along the branches and trunk. Each round fruit is covered by yellowish, thick, leathery skin. Underneath the skin, the fruit is divided into five or six slices of translucent, juicy flesh. The flesh is slightly acidic in taste, although ripe specimens are sweeter. Green seeds are present in around half of the segments, usually taking up a small portion of the segment although some seeds take up the entire segment's volume. In contrast with the sweet-sour flavor of the fruit's flesh, the seeds are extremely bitter. The fruit taste has been compared to a combination grape and "perfect" grapefruit with no bitterness. Yet the seeds if bitten have the bitterness of a grapefruit yet stronger. The sweet juicy flesh contains sucrose, fructose, and glucose.
http://en.wikipedia.org/wiki/Lansium_domesticum