Local names:
English (Wax-apple,water apple,malay apple,Java apple), Filipino (makopa), Indonesian (jambu klampok), Malay (jambu air mawar), Thai (chomphu-khieo), Vietnamese (roi)
Syzygium samarangense is a tree to 15 m tall, with short and crooked trunk, 25-50 cm diameter, often branched near the base and with wide, irregular canopy. Leaves opposite, elliptic to elliptic-oblong, 10-25 cm x 5-12 cm, coriaceous with thin margin, pellucid dotted, rather strongly aromatic when bruised; petiole thick, 3-5 mm long. Inflorescences terminal and in axils of fallen leaves, 3-30-flowered; flowers 3-4 cm in diameter, calyx-tube ca. 1.5 cm long, ventricose at apex, lobes 3-5 mm long; petals 4, orbicular to spathulate, 10-15 mm long, yellow-white; stamens numerous, up to 3 cm long; style up to 3 cm long. Fruit a berry, broadly pyriform, crowned by the fleshy calyx with incurved lobes, 3.5-5.5 cm x 4.5-5.5 cm, light red to white; flesh white spongy, juicy, aromatic, sweet-sour in taste. Seeds 0-2, mostly suppressed, globose, up to 8 mm in diameter.
Ecology
The trees are at home in fairly moist tropical lowlands up to 1200 m elevation. Wax jambu grows best in areas with a fairly long dry season. This does not mean that this species is drought-resistant. The species require a reliable water supply and are often planted along streams or ponds.
Native range
Fiji, India, Indonesia, Malaysia
Tree management
Tree spacing ranges from 8-10 m. The trees receive little attention after the first year or two when manuring, weeding, mulching and watering ensure rapid increase of tree volume. Trees which bear well benefit from compound fertilizers applied after harvest and supplemented with a top dressing as soon as the inflorescences are being formed. There appears to be no experience with pruning or fruit thinning. The fruits have a thin skin and are delicate; they need to be picked by hand twice a week and handled with care. The fruit should be consumed or preserved within a few days from harvest. A five-year-old wax jambu may yield 700 fruit.
The trees are at home in fairly moist tropical lowlands up to 1200 m elevation. Wax jambu grows best in areas with a fairly long dry season. This does not mean that this species is drought-resistant. The species require a reliable water supply and are often planted along streams or ponds.
Propagation from seed is common. Seeds are sometimes abortive, and some wax jambus tend to be seedless. Seeds lose their viability quickly and should be sown fresh from the fruit. Clonal propagation through air layers, cuttings or budding is not difficult. Air layering is commonly employed in South-East Asia. The modified Forkert method is recommended for budding. Seedlings of the same or other Syzygium species are used as rootstocks. In Java 'jambu klampok' or 'kopo' (S. pycnanthum Merr. & Perry, syn. Eugenia densiflora (Blume) Duthie) is recommended as rootstock because it is hardy and not attacked by termites.
The tree is grown for their fruit, which substitute for one another in the marketplace. It is not easy to distinguish between the various S. aqueum and S. samarangense fruits. The ripe fruit is sweet and is mainly eaten fresh. In Indonesia wax jambu is used in fruit salads ('rujak') and they are also preserved by pickling ('asinan'). Eighty per cent or more of the fruit is edible. The composition the species per 100 g edible portion: water more than 90%, protein 0.3 g, fat none, carbohydrates 3.9 g, fibre 1 g, vitamin A 253 IU, vitamin B1 and B2 traces, vitamin C 0.1 mg, energy value 80 kJ/100 g (analysis for wax jambu in Thailand).Timber: The wood is reddish, hard and grows to dimensions large enough for construction purposes.
Medicine: Various parts of the tree are used in traditional medicine, and some have in fact been shown to possess antibiotic activity.