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'''== Trade groups''' == Chengal: heavy hardwood, a single species, ''Neobalanocarpus heimii'' (King) P. Ashton, Fl. Malesiana, ser. I, 9: 388 (1982), synonym: ''Balanocarpus heimii'' King (1893).

*Chengal

Chengal is a popular and well-known timber of Peninsular Malaysia. For the period 1986-1990 the average domestic log and sawn timber prices in December were US$ 123/m³and US$ 242/m³respectively. In this period Peninsular Malaysia exported an average of 28 500 m³of sawn timber annually, while 69 000 m³or 71% was consumed domestically. In 1992 the export of sawn chengal timber was 8000 m³with a value of US$ 2.1 million. Malaysia is the only exporter of chengal sawn timber; Thailand is the main importer. Because collecting the dammar is fairly labour-intensive, an attempt to create a firm trade has failed.

Chengal is a heavy hardwood. The sapwood is pale yellow with fine yellow ripple marks visible to the naked eye, distinctly demarcated from the heartwood. The colour of the heartwood is yellow-green when freshly cut, weathering to dark tan-brown. The density is 915-980 kg/m³at 15% moisture content. The grain is interlocked, texture moderately fine and even.

Chengal is classified as naturally durable and is normally very resistant to termite attack and fungal infestation. Under graveyard test conditions, untreated stakes of 50 mm × 50 mm × 600 mm lasted 9 years. Treated stakes of the same size and under the same test conditions lasted about 19 years. Untreated railway sleepers (238 mm × 125 mm × 1950 mm) laid under severe environmental conditions had an average life of 19 years. Chengal is rated as moderately difficult to treat with preservatives. Using test sticks of 900 mm × 65 mm × 65 mm, and applying the standard open tank treatment using a mixture of equal parts of creosote and diesel fuel, an average absorption of 68 kg/m³was obtained.

After 6 hours extraction, chengal flour was found to have 23% hot water extractives and 32.6% methanol extractives. Impregnation of these extractives into rubberwood conferred a certain degree of resistance to the fungus ''Coriolus versicolor'' , while chengal wood blocks extracted with water or methanol retained their resistance to the same fungus.

When dry-wood termites ( ''Cryptotermes cynocephalus'' ) are exposed to wood blocks and wood extractives of ''N. heimii'' and the light red meranti ''Shorea ovalis'' (Korth.) Blume, the termites' survival and wood consumption is significantly higher in the meranti than in chengal. The bioassays with sawdust, extracted sawdust and treated filter paper further indicated that the dry-wood termites survived significantly better on ''S. ovalis'' than on ''N. heimii'' test material.

The best grades of the dammar are pale and transparent but it darkens when stored. It is a usable material for making spirit-varnish, normally with turpentine or naphtha as a solvent. The usual melting point of 90-100C 100° C and its hardness make it superior to other dammars of the same type. The defect of cloudiness in no way detracts from the utility of the varnish, which is to produce a lustrous coating.

*A large tree, sometimes over 60 m tall; bole straight and cylindrical, unbranched for 30 m or more (but sometimes irregular and low-branched), with an average diameter of 90 cm, prominently buttressed; outer bark hard, shallowly irregularly longitudinally fissured, becoming shaggy in old specimens, falling in long scales, dark-coloured; inner bark 1.5 cm thick, fibrous, yellow, exuding a clear, colourless or golden dammar; twigs slender, ribbed, glabrescent. *Leaves alternate and simple, leathery, elliptical-lanceolate, 7-17 cm × 2.3-5 cm, acuminate, at base rounded to cuneate, unequal, pinnately veined with 9-12 pairs of ascending and arched veins, slightly sunken on the upper surface, but prominent and glabrous or only sparsely pubescent on the lower, tertiary venation reticulate-scalariform; petiole 5-10 mm long; stipules narrowly oblong, to 12 mm long, spreading, early caducous. *Inflorescence paniculate, terminal or axillary, up to 9 cm long, singly branched, puberulent. *Flowers bisexual, actinomorphic, ovoid in bud, up to 4 mm × 3 mm; sepals 5, subequal, imbricate at base, broadly ovate, acute, outside caducous puberulent; petals 5, elliptical, cream-white or greenish-yellow, outside densely buff pubescent; stamens 15, glabrous, filaments slender and tapering, anthers linear-oblong, yellow, with small, straight appendages; ovary single, ovoid, glabrous, surmounted by a filiform style with a minute stigma. *Fruit an oblanceolate, cylindrical nut on a short, stout stalk, up to 5.5 mm × 2.5 mm, shortly apiculate, shining, embraced at the base by a cup formed by the enlarged, woody, saccate sepals, the outer 2 of which are slightly smaller and thicker than the inner 3. *Seedling with epigeal germination; cotyledons very unequal, only the dorsal one reaching the apex of the nut; first 4-5 leaves in a whorl, subsequent ones arranged spirally.

*Heartwood dark brown, light yellow-brown when fresh; sapwood pale yellow and distinct from the heartwood. *Grain generally shallowly to deeply interlocked, rarely straight. *Texture fine; planed surface lustrous, often with vague stripe figure. *Growth rings indistinct or absent; vessels not visible to the naked eye, tyloses visible with hand lens; parenchyma barely visible with a lens, generally in very fine, short tangential lines, marginal parenchyma rarely present; rays visible with a lens, rather narrow and short; ripple marks distinct and visible to the naked eye. *Intercellular canals visible with a lens in long tangential rows appearing as white lines, sometimes infrequent.

*Growth rings indistinct or absent. *Vessels diffuse, (7-)11-14(-18)/mm², often solitary, but occasionally in short radial multiples, 120-220μm in diameter, 400-700μm in vessel element length; perforation plates simple; intervessel pits alternate, vestured, circular to oval, 6-8μm; vessel-ray pits with much reduced borders to apparently simple, rounded or angular (occasionally horizontal to vertical and of two distinct sizes, sometimes difficult to find); tyloses common. *Vasicentric tracheids present. *Fibres 1.2-2.0 mm long, non-septate, thin- to very thick-walled, with simple to minutely bordered pits. *Axial parenchyma predominantly diffuse to diffuse-in-aggregates, occasionally scanty paratracheal to vasicentric, with 4-8 cells per parenchyma strand. *Rays 6-8/mm, 330-380μm in height, mostly heterocellular with 1(-3) rows of upright and/or square marginal cells, often procumbent, square and upright cells mixed throughout the ray, mostly 3-5 cells wide; sheath cells often present; all rays storied, 3 tiers/mm. *Prismatic crystals generally in ray cells (upright/square cells and procumbent cells), often not common. *Silica bodies absent. *Intercellular canals in long tangential lines, infrequent to occasional, often occluded with white deposits.

As in most ''Dipterocarpaceae,'' , germination of chengal seeds is rapid, almost without any dormancy. Germination is similar to that in ''Hopea'' . The radicle extrudes from the apex of the nut, splitting it into 3 equal valves. Seedling leaves have very long drip-tips and are purple-bronze or bluish when young. Saplings are frequently sympodial in growth which is the result of their intermittent growth. Shoot elongation takes place in flushes during which several nodes and leaves are produced in rapid sequence. These periods alternate with dormancy, during which the apical bud is aborted. The branchlets are drooping.

The taxonomic position of ''Neobalanocarpus'' is dubious but it is believed to be closely related to ''Hopea'' section and subsection ''Hopea'' . The highly irregular pattern of meiosis might be a reflection of hybridity which may account for the doubt about its taxonomic position.

The fruits are best stored at about 14C14° C. After storing the fruits at this temperature for 50 days with a loss of 18.7% of the original moisture content and application of a fungicide, they showed no damage. Further reducing of the moisture content to just over half of that of fresh fruits did not kill them either.

Chengal fruits are often attacked by a seed beetle, ''Coccotrypes graniceps'' , and its larvae. A ''Laspeyresia'' species ( ''Lepidoptera-Tortricidae'' ) is a shoot-borer often causing severe damage to saplings 1-3 m high. It shows a marked preference for strong, sappy shoots. A pinhole borer attacks the living tree; it has not yet been collected but it is presumed to be a species of ''Diapus'' ( ''Coleoptera-Platypodidae'' ).

* Yap, S.K., 1981. Collection, germination and storage of dipterocarp seeds. Malaysian Forester 44: 281-300. | '''10''' | * Yap, S.K., 1985. Gregarious flowering of dipterocarps: some observations based on fixed tree populations in Selangor and Negeri Sembilan, Malay Peninsula. In: Kostermans, A.J.G.H. (Editor): Proceedings of the third round table conference on dipterocarps, Samarinda. UNESCO-ROSTSEA, Jakarta & SEAMEO-BIOTROP, Bogor. pp. 305-317.

'''== Other selected sources''' 6, 32, 96, 144, 159, 190, 297, 359, 417, 473, 511, 809.==

*W.C. Wong (general part, properties), *R.B. Miller (wood anatomy) & * G. dos Santos (wood anatomy)