Common name: Jelutong

Jelutong is a large, gum-yielding tree native to Southeast Asia, with a natural range extending from peninsular Thailand to Malaysia, Singapore, and Indonesia. 

In natural forests, it is a tall tree, reaching up to 60 meters (198 ft), with a straight, round trunk up to 2.5 m (8 ft) in diameter and no branches for the lower half of its height. On open sites, it is more commonly under 30 meters (98 ft), with a low-branching trunk forming a pyramidal crown.

The leaves are elongated and oval, 12 to 25 cm (5 to 10 in) long, emerge orange-red before becoming glossy green, and occur in whorls of about six at the ends of the branches. In seasonally dry areas, they fall off the tree to conserve water, but in constantly humid climates, they remain on the tree year-round.

The flowers are bisexual, small, white, star-shaped and held in clusters arising at the leaf bases. They bloom in the rainy season, open at night for pollination, then fall the next day, creating a white carpet on the ground. 

The fertilised flowers are followed by curved, chocolate-brown seedpods up to 40 cm (1.3 ft) long, containing numerous winged seeds.

Material uses

Latex - Jelutong has long been exploited for its latex, tapped from the trunk, mainly as a substitute for chicle from the Sapodilla tree (Manilkara zapota) for use as chewing gum.

Bio-based plastic - Because of its non-elastic properties, it was once also used to insulate cables and electrical wires and to provide material for dental work and waterproofing.

The latex is tapped by making incisions in the trunk, similar to harvesting latex from the Rubber tree (Hevea brasiliensis). The collected latex is then coagulated with phosphoric acid and pressed into blocks, stored underwater to prevent oxidation, which otherwise darkens the colour. Trees in Malaysia average about 11 litres (3 gallons) of latex per month when tapped daily, yielding about 3.5 kg (7.7 lbs) of coagulated gum.

Softwood - Jelutong wood is light- to medium-weight, ranging from 350 to 460 kilograms per cubic meter (22 to 29 lbs per cubic ft), and has low natural resistance to rot, decay, and wood-boring insects.

Timber and lumber - The fresh-sawn wood turns creamy-white or pale yellow on exposure and dries well, with little tendency to warp or split.

Boxes, crates and pallets - Typically, its uses include making wooden boxes,

Wood craft and wares - ...blackboards, picture frames and light articles such as pencils, toy models, match-boxes and fishing lures.

Manufactured wood - The wood is also pulped for insulation or is sliced into thin sheets to make plywood.

Natural cork - Wood taken from the roots is used as a cork substitute.

Environmental uses

Public garden tree - Jelutong is a handsome tree occasionally planted in urban gardens and parks for its shapely form and attractive foliage.

Climate

Grows naturally in humid to very humid tropical lowland climates, generally frost-free areas with annual lows of 20 to 25°C, annual highs of 28 to 35°C, annual rainfall of 1800 to 5000 mm and a dry season of 3 months or less. 

Growing

New plants are usually raised from seed sown in containers in a free-draining soil-and-sand mix. Seedlings are raised in a nursery in shade until planting, when they are about eight to twelve months old or 40 cm (1.3 ft) tall.

It performs best in free-draining clay and loam soils that are moderately acidic to neutral (pH 5.0 to 7.0) and in sites with full to partial sun exposure. It tolerates drought poorly and struggles in slow-draining or waterlogged soils.

Problem features

The winged seeds allow wind to disperse them over a wide area. It is recorded as a weed in the Congo in West Africa, though it is not considered a serious weed. 

Books

• C.A.B. International 2013, The CABI encyclopedia of forest trees, CABI Publishing, Wallingford, Oxfordshire

• Chudnoff, M. 1984, Tropical timbers of the world, Forest Service, U.S. Department of Agriculture (USDA), Washington, D.C.

• Coppen, J. J. W. 1995, Gums, resins and latexes of plant origin, Food and Agriculture Organization of the United Nations (FAO), Rome

• Forest Products Laboratory (U.S.) 2007, The encyclopedia of wood, Skyhorse Pub, New York

• Holttum, R. E. & Enoch, I. C. 2010, Gardening in the tropics : the definitive guide for gardeners, Marshall Cavendish Editions, Singapore

• Kukachka, B. F & Forest Products Laboratory (U.S.) 1970, Properties of imported tropical woods, United States, Department of Agriculture, Forest Service, forest Products Laboratory, Madison

• Macmillan, H. F. 1943, Tropical planting and gardening : with special reference to Ceylon, 5th ed, Macmillan Publishing, London

• Mors, W. B & Rizzini, C. T. 1966, Useful plants of Brazil, Holden-Day Publishing, San Francisco, California

• Porter, T. 2012, Wood : identification & use, Compact edition, Guild of Master Craftsman Publications, Lewes, East Sussex

• Randall, R. P. 2007, The introduced flora of Australia and its weed status, Cooperative Research Centre for Australian Weed Management, Glen Osmond, South Australia

• Reyes, G. 1992, Wood densities of tropical tree species, U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station, New Orleans, Louisiana

• Scheffer, T. C & Morrell, J. J. 1998, Natural durability of wood : a worldwide checklist of species, Forest Research Laboratory, Oregon State University, Corvallis, Oregon

Articles, Journals, Reports and Working Papers

• Seth, M.K 2003-10-01, 'Trees and their economic importance' The Botanical Review, vol. 69, no. 4, pp. 321(56).