The rambutan is a fruit grown primarily in Southeast Asia, and is cousin to the longan and the lychee. It grows on trees that are 10-20 feet (3.05-6.1 m) high. The trees are prized in landscaping because they are evergreens. The exterior of the rambutan can be orange to deep red in color. Each fruit is small, generally no more than 2 inches (5 cm) long. The interior can be white or light pink in color.
The rambutan produces two crops each year, a smaller crop in mid-spring and a larger crop in late fall. Not all rambutan trees produce crops, because some trees are male. Some trees are hermaphrodites, producing both male and female blossoms, while others are exclusively female. The hermaphrodite tree is the most prized.
The rambutan is a sweet fruit that most palates find appealing. Ten to 20 fruits will grow in clusters. Their exterior appearance looks a bit foreboding, as it is covered in spikes. The spikes, however, are soft and will not harm one who touches or handles the rambutan.
The rambutan tree reaches 50 to 80 ft (15-25 m) in height, has a straight trunk to 2 ft (60 cm) wide, and a dense, usually spreading crown. The evergreen leaves are alternate, pinnately compound, 2 3/4 to 12 in (7-30 cm) long, with reddish rachis, hairy when young, and 1 to 4 pairs of leaflets, subopposite or alternate, elliptic to oblong-elliptic, or rather obovate, sometimes oblique at the base; slightly leathery; yellowish-green to dark-green and somewhat dull on the upper surface, yellowish or bluish-green beneath; 2 to 8 in (5-20 cm) long, 1 to 4 1/3 in (2.5-11 cm) wide, the 6 to 15 pairs of principal veins prominent on the underside. The small, petalless flowers, of three kinds: males, hermaphrodite functioning as males, and hermaphrodite functioning as females, are borne in axillary or pseudo-terminal, much branched, hairy panicles.
The fruit is ovoid, or ellipsoid, pinkish-red, bright-or deep-red, orange-red, maroon or dark-purple, yellowish-red, or all yellow or orange-yellow; 1 1/3 to 3 1/8 in (3.4-8 cm) long. Its thin, leathery rind is covered with tubercles from each of which extends a soft, fleshy, red, pinkish, or yellow spine 1/5 to 3/4 in (0.5-2 cm) long, the tips deciduous in some types. The somewhat hairlike covering is responsible for the common name of the fruit, which is based on the Malay word “rambut”, meaning “hair”. Within is the white or rose-tinted, translucent, juicy, acid, subacid or sweet flesh, 1/6 to 1/3 in (0.4-0.8 cm) thick, adhering more or less to the ovoid or oblong, somewhat flattened seed, which is 1 to 1 1/3 in (2.5-3.4 cm) long and 2/5 to 3/5 in (1-1.5 cm) wide. There may be 1 or 2 small undeveloped fruits nestled close to the stem of a mature fruit.
Origin and Distribution
The rambutan is native to Malaysia and commonly cultivated throughout the archipelago and southeast Asia. Many years ago, Arab traders introduced it into Zanzibar and Pemba. There are limited plantings in India, a few trees in Surinam, and in the coastal lowlands of Colombia, Ecuador, Honduras, Costa Rica, Trinidad and Cuba. Some fruits are being marketed in Costa Rica. The rambutan was taken to the Philippines from Indonesia in 1912. Further introductions were made in 1920 (from Indonesia) and 1930 (from Malaya), but until the 1950’s its distribution was rather limited. Then popular demand brought about systematic efforts to improve the crop and resulted in the establishment of many commercial plantations in the provinces of Batangas, Cavite, Davao, Iloilo, Laguna, Oriental Mindoro and Zamboanga.
Popular varieties in Malaya include ‘Chooi Ang’, ‘Peng Thing Bee’, ‘Ya Tow’, ‘Azimat’, and ‘Ayer Mas’. Dr. J.J. Ochse described 6 named varieties in Indonesia:
- ‘Lebakbooloos’ – a broad-topped tree with dark-red fruits having uncrowded spines 3/5 in (1.5 cm) long, and grayish-white, tough, subacid flesh 1/5 in (0.5 cm) thick, frequently difficult to separate from the seed and often takes pieces of the testa with it. Ships well over long distances. (Cultivated also in India).
- ‘Seematjan’ – Tree has an open crown and long, flexible branches. Fruits are dark-red with spines to 3/4 in (2 cm) long. In Java the tree is especially prone to attack by various insects. It is cultivated also in India and in the Philippines where it has averaged 16 lbs/acre (16 kg/ha). There are 2 forms: 1) ‘Seematjan besar’ with small fruit, thin rind, spines fairly far apart; very sweet, somewhat coarse, fairly juicy flesh to which the coarse, fibrous testa tightly adheres; 2) ‘Seematjan ketjil’ (or ‘Koombang’) – the fruit has soft, tough, and less sweet flesh to which the seed coat does not tightly adhere.
- ‘Seenjonja’ – Tree low-growing; has a drooping crown. Fruit nearly ovoid, about 1 1/2 in (4 cm) long and 1 1/5 in (3 cm) wide; dark wine-red with slender, flexible spines about 2/5 in (1 cm) long. Flesh clings firmly to the seed. In the Philippines has yielded on the average 41 lbs/acre (41 kg/ha).
- ‘Sectangkooweh’ – Tree broad-topped. Fruit flattened ellipsoid, about 2 in (5 cm) long, 1 1/2 in (4 cm) wide with slim spines 2/5 in (1 cm) long. Rind is thin, pliable, tough. Flesh yellowish-white, sweet, clings tightly to the thick testa which separates from the seed. Fruits stand long-distance shipment.
- ‘Seelengkeng’ – Tree low-growing with drooping crown. Fruit ovoid, 1 1/5 in (3 cm) long, 3/4 in (2 cm) wide, with very fine, soft spines. Flesh slightly glossy, tough, moderately sweet, and separates from the seed with a few particles of testa clinging to it. Air-layers are unsatisfactory, so it is rare in cultivation and expensive on the market. Much favored by Chinese because of its resemblance to the lychee. (Cultivated also in India.)
- ‘Seekonto’ – Tree has broad crown; is fast-growing. Fruits ellipsoid, faintly flattened, about 2 in (5 cm) long, 1 1/2 in (4 cm) wide. Spines are thick and short. Flesh is dull, grayish-white, somewhat coarse and dry; clings to the testa which separates readily from the seed.
- ‘Maharlika’ (no description available) has yielded 21 lbs/ acre (21 kg/ha) in the Philippines.
Yellow-fruited rambutans are called ‘Atjeh koonig’ in Batavia. In Malaya, ‘Rambutan gading’ indicates a yellow type.
Among the many “races” of rambutan in Malaya, the best “freestone” types are found in Penang. One race with a partly free stone is known as ‘rambutan lejang’. Burkill says that some rambutans are so sour that monkeys are reluctant to eat them.
In 1950, Philippine agriculturists undertook a program of selection and the creation of a Testing Plot at the Provincial Nursery, Victoria, Oriental Mindoro. There they assembled 360 trees of which 140 were found to be bearing in 1960 and 196 (mostly males) were non-bearing. Observations of the bearing trees there and at the Arago Farm not far away, resulted in the selection of 21 clones which they classified into 4 groups according to fruit size: 1) very large, 14 or less per lb (31 or less/kg); 2) large, 15 to 16 per lb (32-36/kg); 3) medium, 17 to 19 per lb (37-41/kg); 4) small, 20 or more per lb (42 or more/kg).
The main characteristics of the 21 named selections are here summarized:
- ‘Queen Zaida’ – Dark-red, oblong, medium-size; flesh thick (38.76% of fruit), sweet, juicy; freestone; 60% of fruits kept well for 2 weeks in cold storage. Yield: 275 lbs (125 kg) per tree at 20 years of age.
- ‘Baby Eulie’ – Light-red, very large, flesh thick (39.92% of fruit), soft, freestone. Kept well only 1 week at 60º F (15.56º C). Yield: 352 lbs (160 kg) per tree at 8 years of age.
- ‘Princess Caroline’ – Dark-red, small, rind pliable; flesh thick (44.14% of fruit); seeds small. Kept well for 2 weeks at 60º F (15.56º C). Yield; 440 lbs (200 kg) per tree at 8 years of age.
- ‘Quezon’ – Yellowish- red, small to medium; rind pliable; flesh thick (38.24% of fruit); sweet, slightly acid, juicy. Yield: 343 lbs (156 kg) per tree at 8 years of age.
- ‘Roxas’ – Dark-red; medium-sized; flesh thick (42.97% of fruit); juicy, sweet, adheres to seed. Yield: 429 lbs (195 kg) per tree at 8 years of age.
- ‘Zamora’ – Yellowish rind with pale-pink spines; oblong; small; rind hard; flesh thick (38.29% of fruit), juicy and sweet. Yield: 330 lbs (150 kg) per tree at 7 years of age. Ripens mid-to late October. After 2 weeks of refrigeration at 60º F (15.56º C) 80% of the fruits were still in good condition.
- ‘Quirino’ – Yellowish with pinkish-red spines; small; flesh thick (32.78 % of fruit), juicy and sweet. Borne in large clusters of up to 85 fruits each.
- ‘Magsaysay’ – Dark-red to near-black with dark-red spines; oblong, large; rind pliable; flesh thick (42.68% of fruit); juicy, sweet; freestone. Yield: 176 lbs (80 kg) per tree at 6 years of age.
- ‘Santo Tomas’ – Yellowish-pink with reddish-pink, soft spines. Nearly round; rind hard; flesh thick (43.25% of fruit); seed small. Yield: 352 lbs (160 kg) per tree at 8 years of age.
- ‘Victoria’ – Yellowish with red spines; rind thick; flesh thick, juicy, sweet, freestone. Yield: 132 lbs (60 kg) per tree at 6 years of age. Early in season (mid-July).
- ‘Baby Christie’ – Yellowish-red with soft, silvery-pink spines; large. Flesh thick (36.41% of fruit).
- ‘Governor Infantada’ – Oblong, very large; rind pliable; flesh thick (39.28% of fruit), juicy, sweet and slightly acid; adheres tightly to seed. Yield: 330 lbs (150 kg) per tree at 6 years of age. Fruits keep only 1 week at 60º F (15.56º C).
- ‘Laurel, Sr.’ – Pinkish-red, small; flesh thick (39.76% of fruit). Tree very low-growing, spreading.
- ‘Fortich’ – Yellowish-red; medium-sized; flesh thick (40.95% of fruit); juicy, sweet; freestone. Early in season.
- ‘Osmena, Sr.’ – Purple-red; medium-sized; flesh thick (38.90% of fruit); juicy, sweet; freestone. Ripens late in season.
- ‘Ponderosa Ferreras’ (from Arago, Farm) – Crimson red with very prominent spines; very large; flesh thick (35.73% of fruit); juicy, sweet, freestone. Early in season. Yield: 303 lbs (138 kg) per tree at 6 years of age.
- ‘Rodrigas’ (from Arago Farm) – Medium-sized; flesh thick (38.46% of fruit).
- ‘Manahan’ (from Arago Farm) – Medium-sized; flesh thick (37.37% of fruit).
- ‘Santan’ (from Arago Farm) – Flesh thick (34.26% of fruit).
- ‘Arago’ (from Arago Farm) – flesh very thick (41.42% of fruit).
- ‘Cruz’ or ‘Cruzas’ (from Arago Farm) – flesh medium-thick (26.15% of fruit).
About 1960, 10 outstanding rambutans were selected in an evaluation of 100 seedling trees of the unsurpassed Indonesian ‘Seematjan’, also ‘Seenjonja’, ‘Maharlika’, ‘Divata’, ‘Marikit’, ‘Dalisay’, ‘Marilag’, ‘Bituin’, ‘Alindog’, and ‘Paraluman’.
sources: wisegeek.com, hort.purdue.edu, easymangosteen.com