In the Malay Archipelago are found several valuable tropical fruits which have not yet become extensively cultivated elsewhere. The rambutan is one of them. It is grown in nearly every garden in Singapore and Penang, and its fruit is one of the most delicious of the region. It resembles the litchi in character.
As seen in cultivation, the tree is 35 or 40 feet high, erect and stately in appearance. The compound leaves are composed of five to seven pairs of elliptic, obovate, or oblong leaflets, glabrate, about 4 inches long, shining and dark green above, paler beneath. The flower-panicles are axillary and terminal, loose and spreading in form, the flowers small, pubescent, the calyx campanulate, five- or six-cleft, the petals wanting. The fruits, which are produced in clusters of ten or twelve, are oval, about 2 inches in length, and covered with soft fleshy spines1/2 inch long. They are crimson in color, sometimes greenish, yellowish, or orange-yellow. The outer covering, from which the spines arise, is thin and leathery, and is easily torn off, exposing the white, translucent, juicy flesh (aril) which adheres to the oblong, pointed, and flattened seed. The flavor is acidulous, somewhat suggesting that of the grape. It is usually relished by Europeans, though considered slightly inferior to its relative the litchi.
Apparently the rambutan is well distributed throughout the Malay Archipelago. H. F. Macmillan says: "It is curious that this fruit, which is so common in the low-country of Ceylon and in the Straits, appears to be scarcely known in India, Mauritius, Madagascar, etc." It has been introduced into the American tropics by the United States Department of Agriculture, but is not yet well established there.
The common name is taken from the Malayan word rambut, meaning hair, and has reference to the long soft spines with which the fruit is covered. Rambustan, ramboetan, and ram-botang are forms sometimes used. The French spell it ram-boutan and sometimes call the fruit litchi chevelu (hairy litchi).
The rambutan is eaten fresh. It has been found to contain about the same amount of sugar as the litchi and longan, as follows: Saccharose 7.8 per cent, dextrose 2.25, and levulose 1.25.
In climatic requirements the rambutan must be considered strictly tropical. It thrives in Ceylon up to elevations of 2000 feet, which means that it does not grow in the cooler parts of the island. It likes a moist hot climate and may not, therefore, succeed anywhere on the mainland of the United States, although there is a possibility that it might be grown in extreme southern Florida. It should be practicable to grow it in many parts of the American tropics.
Little is known regarding the culture of the tree. It succeeds on deep, rich, and moist soils, but its adaptability as regards soil and other conditions is not definitely understood. It is propagated by seed, and by air-layering in the same manner as the litchi; it has also been inarched successfully. Mature trees are productive, the bearing habits of the rambutan resembling those of the litchi. It is said that there are fifteen varieties, differing in color, size, and flavor, cultivated in the Malayan region, but they are not well known horticulturally.