The pulasan tree is a handsome ornamental; attains 33 to 50 ft (10-15 m); has a short trunk to 12 to 16 in (30-40 cm) thick; and the branchlets are brown-hairy when young. The alternate leaves, pinnate or odd-pinnate, and 6 3/4 to 18 in (17-45 cm) long, have 2 to 5 pairs of opposite or nearly opposite leaflets, oblong-or elliptic-lanceolate, 2 1/2 to 7 in (6.25-17.5 cm) long and up to 2 in (5 cm) wide; slightly wavy, dark-green and barely glossy on the upper surface; pale, somewhat bluish, with a few short, silky hairs on the underside. Very small, greenish, petalless flowers with 4-5 hairy sepals, are borne singly or in clusters on the branches of the erect, axillary or terminal, panicles clothed with fine yellowish or brownish hairs. The fruit is ovoid, 2 or 3 in (5-7.5 cm) long, dark- or light-red, or yellow, its thick, leathery rind closely set with conical, blunt-tipped tubercles or thick, fleshy, straight spines, to 3/8 in (1 cm) long. There may be 1 or 2 small, undeveloped fruits nestled close to the stem. Within is the glistening, white or yellowish-white flesh (aril) to 3/8 in (1 cm) thick, more or less clinging to the thin, grayish-brown seedcoat (testa) which separates from the seed. The flavor is generally much sweeter than that of the rambutan. The seed is ovoid, oblong or ellipsoid, light-brown, somewhat flattened on one side, 3/4 to 1 1/3 in (2-3.5 cm) long.
The pulasan is native to Western Malaysia. Wild trees are infrequent in lowland forests around Perak, Malaya but abundant in the Philippines at low elevations from Luzon to Mindanao. The tree has long been cultivated in Malaya and Thailand; is rarely domesticated in the Philippines. Ochse reported that there were extensive plantings in Java only around Bogor and the villages along the railway between Boger and Djakarta.
The tree was planted at the Trujillo Plant Propagation Station in Puerto Rico in 1926 and young trees from Java were sent to the Lancetilla Experimental Garden, Tela, Honduras, in 1927. The latter were said in 1945 to be doing well at Tela and fruiting moderately. The pulasan is little-known elsewhere in the New World except in Costa Rica where it is occasionally grown and the fruits sometimes appear on the market.
Ochse refers to 2 forms of pulasan in Java: in one group, distinguished as "Seebabat' or 'Kapoolasan seebabat', the fruit is mostly dark-red, the tubercles are crowded together, the flesh is very sweet and juicy and separates easily from the seed. In the other group, the fruit is light-red and smaller, the tubercles are not so closely set, and the flesh adheres firmly to the seed.
Wester mentions a fine variety growing in Jolo. The plants introduced into Honduras were 2 superior varieties called 'Asmerah Tjoplok' and 'Kapoelasan mera tjoplok'. There are some trees in Malaya and in Thailand that bear seedless fruits and these are being vegetatively propagated.
The pulasan is ultra-tropical and thrives only in very humid regions between 360 and 1,150 ft (110-350 in) of altitude. In Malaya, it is said that the tree bears best after a long, dry season.
There is little information on the soil requirements of the pulasan but Ochse says it must be constantly moist. He was of the opinion that the richer soil around Bogor contributed to the superior quality of the fruits grown in that area.
Planting of seeds is not favored because the seedlings may be male or female. As with the rambutan, air-layers are very short-lived. Budding is successful if it is done in the rainy season on rootstocks already set out in the field so that they will not be subject to transplanting which causes many fatalities, particularly during dry weather.
The trees require less space than rambutan trees and can be 26 to 33 ft (8 to 10 m) apart each way. As a rule, they receive little or no fertilizer or other cultural attention.
The flesh of ripe fruits is eaten raw or made into jam. Boiled or roasted seeds are used to prepare a cocoa-like beverage.