4507

5(2): Timber trees; Minor commercial timbers

Pentaspadon Hook.f.

Trans. Linn. Soc. Lond. 23: 168 (1860).

ANACARDIACEAE

x = unknown; 2n = unknown

Trade groups Pelajau: lightweight to medium-weight hardwood, Pentaspadon motleyi Hook.f. and Pentaspadon velutinus Hook.f.

Pelajau. Indonesia: pelaju. Malaysia: pelong (Peninsular), plajau (Sarawak), empelanjau (Dayak, Sabah). Thailand: toei-na (Satun), oei-nam (Ranong). Vietnam: vi h[uf]ng trung.

Pentaspadon consists of 6 species, and is found in Vietnam, Thailand, Peninsular Malaysia, Sumatra, Borneo, the Moluccas, New Guinea and the Solomon Islands. Within the Malesian area 3 species occur; 2 species (Pentaspadon motleyi and Pentaspadon velutinus) are large timber trees, the third one (Pentaspadon curtisii (King) Corner) is a small tree with a small area of distribution (peninsular Thailand and Langkawi).

The timber is used for flooring, interior construction, house posts, panelling, partitioning, mouldings, skirtings, planking, fence posts, plywood, boxes and crates, and artifacts. Because of its poor durability, all applications should be under cover. The timber is regarded as suitable for picture frames and veneer.
An oil can be obtained from the trunk. It is called "minyak plang"" in Peninsular Malaysia and "minyak pelanjau"" in Borneo. This black resin and its sediment are used against skin eruptions. The fruits of Pentaspadon motleyi are edible after boiling, and the seeds can be eaten raw or boiled and are regarded as a delicacy in Borneo. An oil can be extracted from the seeds and sprinkled over food. The seed are also used as marbles for children's games.

Pelajau has no real commercial importance and no statistics are available on production and trade. The timber is usually traded in mixed consignments of light hardwood.

Pelajau is a lightweight to medium-weight and moderately hard wood. The heartwood is whitish-yellow or yellow-green to pale grey-pink and often indistinctly demarcated from the sapwood (greenish-white to pale yellow with a pink tinge). The density is 485—825 kg/m³ at 15% moisture content. The grain is straight to shallowly interlocked, texture moderately fine and even.
At 12% moisture content, wood of Pentaspadon velutinus from Thailand has the following mechanical properties: the modulus of rupture c. 81.5 N/mm², modulus of elasticity 8250 N/mm², compression parallel to grain 38 N/mm², compression perpendicular to grain 8 N/mm², shear 17 N/mm², and Janka side hardness 4115 N.
The rates of shrinkage are fairly low to moderately high: from green to 15% moisture content 1.0—2.0% radial and 1.9—4.3% tangential and from green to oven dry c. 4.0% radial and 6.7% tangential. The timber air dries rather slowly, usually without serious defects, although slight checking and end splitting may occur. The sapwood is susceptible to staining during drying. Boards 12.5 mm thick take about 3 months to air dry, boards 25 mm thick 3.5—5 months.
Pelajau is easy to work. It saws comparatively easily, although some gumming up of saw teeth may occur. The wood is easy to plane, bore and turn, giving a smooth finish, except for some picking up of grain on radial surfaces. The nailing properties are rated as poor.
The wood is rated as only moderately durable. Graveyard tests in Malaysia showed an average service life in contact with the ground of 2.5 years. Pelajau should not be used in contact with the ground or in exposed conditions in the tropics. It is susceptible to attack by termites and powder-post beetles. The heartwood is very difficult to treat with preservatives, even when using a pressure treatment. It absorbs up to 7 kg/m³ using the open tank method and an equal mixture of creosote and diesel fuel. However, sapwood absorbs preservatives very well.
The wood has allergenic properties. Medicinal application of the black resin should be done with caution as it may cause severe irritation of the skin, which may be worse than the actual disease.

Usually large, deciduous trees up to 50(—60) m tall; bole straight, cylindrical, branchless for up to 20(—25) m, up to 85 cm in diameter, distinctly buttressed with narrow buttresses up to 5 m high; bark surface smooth to rough or scaly and lenticellate, brown to grey or grey-green, inner bark pink or reddish, with little white latex; crown feathery, completely covered by flowers when flowering. Leaves arranged spirally, crowded towards the end of twigs, imparipinnate, about 10—30 cm long; leaflets opposite to subopposite, entire, often with hairy domatia below. Inflorescence axillary, paniculate; bracts and bracteoles caducous. Flowers actinomorphic, bisexual, 5-merous, fragrant, white or pink or red; calyx lobed; petals imbricate, papillose on both surfaces; stamens 5, opposite the calyx lobes and alternating with 5 staminodes, filaments papillose, anthers basi- or dorsifixed; disk intrastaminal, short-cupular, 10-grooved or wavy outside; pistil consisting of only a single carpel, ovary superior, 1-celled, with a single ovule attached to the side of the cell, hairy, style short, stigma subglobose or slightly 2-lobed. Fruit a drupe, 1-celled, green to purplish, later black, endocarp thin. Seed with testa free from endocarp. Seedling with epigeal germination; cotyledons free, fleshy; first 2 leaves opposite, trifoliolate, subsequent leaves arranged spirally.

— Macroscopic characters:
Heartwood pale pinkish-brown to creamy grey, sometimes greenish-grey, not always clearly demarcated from the pale yellow sapwood, sometimes with a pinkish tinge. Grain straight to shallowly interlocked. Texture moderately fine and even; wood somewhat lustrous, without appreciable figure. Growth rings not evident; vessels small and indistinct to the naked eye, evenly distributed; parenchyma sparse, paratracheal, widely spaced irregular bands of parenchyma rare; rays fine, barely discernible to the naked eye as individual rays; ripple marks absent, although rays may show a wavy tendency horizontally.
— Microscopic characters:
Growth rings inconspicuous or absent. Vessels diffuse, 7—10/mm², solitary (c. 80%) and in radial multiples of 2—3, mostly circular to oval, average tangential diameter 140—160 µm; perforations simple; intervessel pits alternate, rounded to polygonal, 8—9 µm in diameter; vessel-ray pits with much reduced borders, rounded to elongated; helical thickenings absent; tyloses present but not abundant. Fibres c. 1.4 mm long, septate, moderately thin-walled, with inconspicuous simple to minutely bordered pits, mainly confined to the radial walls. Parenchyma scanty paratracheal, in 2—4-celled strands. Rays 4—7/mm, 2—3(—4)-seriate, 400—600 µm high, heterocellular with 1—4 rows of square and upright cells (Kribs type heterogeneous II). Large prismatic crystals present, mainly in marginal ray cells. Silica absent. Horizontal intercellular canals present, sometimes 2 in a single ray.
Species studied: Pentaspadon motleyi, Pentaspadon velutinus.
Although the wood of Canarium spp. is generally distinctly pink with extraneous material in the rays, it may show considerable similarity to the wood of Pentaspadon.

Two 24-year-old Pentaspadon motleyi trees in the arboretum of the Forest Research Institute Malaysia were 24 m tall and had a bole branchless for 5.5 m with a diameter at breast height of 43 cm, indicating a mean annual diameter increment of almost 2 cm.
Leaflets of seedlings are coarsely toothed, later ones entire. Leaves fall after spells of dry weather and flowering occurs together with the development of new leaves and can be once or twice in a year. The crown of the tree may be covered with inflorescences. Growth is in flushes. The architectural model of the tree is that of Fagerlind: it is determined by a monopodial, orthotropic and episodically growing trunk with indefinite growth of the trunk meristem and producing tiers of sympodial and plagiotropic branches.

The genus Pentaspadon belongs to the tribe Rhoeae, together with e.g. the genera Campnosperma, Parishia, Pistacia and Rhus. Within the family, Pentaspadon is characterized by the combination of compound leaves with hairy domatia, 5 fertile and 5 sterile stamens, and a 1-celled ovary.

Species of Pentaspadon usually occur scattered but sometimes co-dominant in primary, or sometimes secondary lowland rain forest, on flat to undulating land, up to 350 m altitude. Although the trees are deciduous, they are found in the humid zone, preferring riparian habitats or seasonally inundated places and swamp forest. They avoid peat soils. In Jambi, Sumatra, pelajau occurs in dipterocarp forest on red-yellow podzolic and lithosol soil types and receiving an average annual rainfall of 2400—2900 mm.

The germination of fresh fruits of Pentaspadon motleyi was 85% in 12—25 days. No commercial planting has been attempted.

Natural forest management systems, such as selective felling systems, are also applicable to forests from which pelajau timber is harvested.

Logs often show a central zone of spongy heart or heart-rot. The black oily resin is tapped in the same way as dammar is collected from Dipterocarpaceae species, i.e. by making a deep cavity in the trunk sloping downwards to the centre of the tree. The cavity is burned to promote the flow of the resin.

The standing stock of pelajau is generally small. In a dipterocarp forest in Sumatra it amounts to 1.5 m³, 2.0 m³ and 3.3 m³ per ha for trees with a diameter of over 60 cm, 50 cm and 35 cm, respectively.

Logs usually float in water and can thus be transported by river.

Pelajau trees are usually found scattered in lowland forest. There is no indication that they are overexploited and becoming rare or endangered.

Pelajau timber is not in great demand, but it is sometimes used as a substitute for meranti which is, however, usually preferred. Although very little is known about silviculture, planting and propagation, prospects for the use of pelajau in timber plantations do not seem to be good.

Beaman, J.H., 1986. Allergenic Asian Anacardiaceae. Clinics in Dermatology 4(3): 191-203.
Browne, F.G., 1955. Forest trees of Sarawak and Brunei and their products. Government Printing Office, Kuching. pp. 52-53.
Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department Sabah, Sandakan. pp. 30-32.
Corner, E.J.H., 1988. Wayside trees of Malaya. 3rd Edition. Vol. 1. Malayan Nature Society, Kuala Lumpur. pp. 122-123.
Desch, H.E., 1941. Manual of Malayan timbers. Malayan Forest Records No 15. Vol. 1. Federated Malay States Government, Kuala Lumpur. pp. 15-17.
Hou, D., 1978. Anacardiaceae. In: van Steenis, C.G.G.J. & de Wilde, W.J.J.O. (Editors): Flora Malesiana. Ser. 1, Vol. 8. Wolters-Noordhoff, Groningen. pp. 395-548.
Kochummen, K.M., 1989. Anacardiaceae. In: Ng, F.S.P. (Editor): Tree flora of Malaya. A manual for foresters. Vol. 4. Forest Research Institute Malaysia. Longman Malaysia SDN. Berhad, Petaling Jaya. pp. 9-57.
Malaysian Timber Industry Board, 1986. 100 Malaysian timbers. Kuala Lumpur. pp. 178-179.
Ng, F.S.P., 1991. Manual of forest fruits, seeds and seedlings. Vol. 1. Malayan Forest Record No 34. Forest Research Institute Malaysia, Kepong. pp. 18, 108-109.
Research Institute of Wood Industry, 1988. Identification, properties and uses of some Southeast Asian woods. Chinese Academy of Forestry, Beijing & International Tropical Timber Organization, Yokohama. p. 8.

I. Soerianegara (general part), N. Tonanon (properties), R.H.M.J. Lemmens (properties), J. Ilic (wood anatomy), M.S.M. Sosef (selection of species)

Pentaspadon motleyi
Pentaspadon velutinus

Soerianegara, I., Tonanon, N., Lemmens, R.H.M.J., Ilic, J. & Sosef, M.S.M., 1995. Pentaspadon Hook.f.. In: Lemmens, R.H.M.J., Soerianegara, I. and Wong, W.C. (Editors): Plant Resources of South-East Asia No 5(2): Timber trees; Minor commercial timbers. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea

The following species in this genus are important in this commodity group and are treated separatedly in this database:
Pentaspadon motleyi
Pentaspadon velutinus