6177

5(3): Timber trees; Lesser-known timbers

Pterygota Schott & Endl.

Melet. Bot.: 32 (1832).

STERCULIACEAE

x = unknown; P. alata: 2n = 40, P. macrocarpa K. Schumann: 2n = 36

Mabin, pterygota (trade name). Malaysia: kasah (Peninsular), melebu (Iban, Sarawak). Papua New Guinea: white tulip oak (En).

Pterygota comprises about 20 species occurring throughout the tropics. In Asia they are found from Bangladesh (Chittagong) to Indo-China, Thailand, throughout the Malesian region (except for Sumatra), the Solomon Islands and northern Australia.

When treated, the wood of Pterygota is suitable for general construction, bridge and wharf superstructure, railway sleepers and poles. It is used for flooring, interior finish, furniture and cabinet work, joinery, mouldings, panelling, cladding, lining, steps, hand rails, tool handles, pattern work, packing boxes, pallets, carvings, shoe heels, toys and novelties and turnery. It is often applied as face veneer and for concrete shuttering. It is also suitable for manufacture of cement-bonded wood-wool board and may be suitable for producing short fibre pulp.

Supplies of Pterygota are generally limited and the wood is mainly used locally, but small amounts are imported into Japan from Papua New Guinea and the Solomon Islands. In 1996 the export from Papua New Guinea amounted to 7800 m³ of round logs at an average free-on-board (FOB) price of US$ 98/m³.

Pterygota yields a medium-weight to heavy hardwood with a density of 460-980 kg/m³ at 15% moisture content. Heartwood pale yellow-white to pale brown, not clearly differentiated from the pale yellow to straw sapwood; grain straight or shallowly interlocked; texture medium to coarse and uneven; wood with silver grain and characteristic ray pattern on radial surface; fresh wood with offensive smell. Growth rings indistinct, occasionally indicated by zones with fewer, or wavier parenchyma bands; vessels moderately large, solitary and in radial multiples of 2-4(-more), occasionally in clusters, tyloses rare, but gummy deposits occasionally present; parenchyma moderately abundant to abundant, scanty paratracheal, vasicentric, or apotracheal in broad, continuous or interrupted bands; rays medium-sized to moderately broad with occasional very wide rays; fine ripple marks present due to storied arrangement of parenchyma cells.
Shrinkage of the wood when seasoned is moderate to high. During preliminary air drying short surface checks usually develop, which extend during kiln drying. It takes about 5 days to kiln dry boards 25 mm thick from the green condition. Quarter-sawn boards develop some end checks whereas back-sawn boards may show severe surface checking. The wood is soft to moderately hard and may be slightly heavier and harder in the periphery of the stem. It is moderately strong, tough and very shock resistant. The wood is fairly easy to saw, plane and finish, but has a tendency to tear when quarter-sawing boards with interlocked grain. A sticky substance is released when sawing green stock, so the saw blades have to be cleaned frequently. Stock may be sliced, but peeling P. horsfieldii may not be satisfactory due to the presence of harder and softer zones. The wood is moderately durable. The sapwood of P. horsfieldii is susceptible to Lyctus. The sapwood and heartwood are permeable when treated with preservatives under pressure. Logs are very susceptible to blue stain, termites and pinhole borer attack unless rapidly removed from the forest and treated with appropriate prophylactic preservatives.
See also the tables on microscopic wood anatomy and wood properties.

Deciduous, monoecious, medium-sized to large trees up to 50 m tall; bole cylindrical to tapering, up to 120 cm in diameter and branchless for up to 36 m, with thin, small to tall buttresses; bark surface smooth to shallowly fissured, mauve-grey, inner bark pale brown; crown dense, dark. Twigs slender, prominently wrinkled. Leaves arranged spirally, simple, entire, palmately veined; stipules subulate, caducous; petiole kneed. Flowers in a short, terminal or subterminal panicle or raceme, unisexual; sepals 5, almost free; petals absent. Male flower with 8-10 or 20-25 sessile anthers placed on a staminal tube and a rudimentary ovary. Female flower with staminodes; ovary superior, with 3-5 partly fused carpels each with many ovules, styles short. Fruit a stalked, globose, woody, many-seeded follicle, splitting on one side. Seeds with a large wing on one side. Seedling with epigeal germination; cotyledons emergent, leafy; hypocotyl elongated; leaves alternate-spiral from the outset (occasionally the first 2 opposite in extra-Malesian species).
In trials in West and East Java with P. alata at 19-31 years of age, the mean annual increment was 0.9-1.9 cm in diameter and 0.8-1.1 m in height. Branches are produced in pseudowhorls and their tips curve upwards in a Terminalia-like fashion. In Peninsular Malaysia P. horsfieldii has been observed to flower and fruit in mast fruiting years. In Thailand P. alata flowers and fruits in December-March. The winged seeds are dispersed by wind.

Pterygota is found scattered or rarely gregarious in primary, lowland rain forest, up to 1000 m altitude, in areas with a short but pronounced dry period. It occurs on fertile soils and apparently tolerates periodic droughts. P. alata prefers flat alluvial soils and periodically inundated localities. In Papua New Guinea P. horsfieldii is locally common in monsoon forest.

Pterygota can be propagated by seed. For P. alata there are about 1250 seeds without wings per kg. Seeds should be sown in the shade and those of P. alata have 80-85% germination in 7-203 days. In a trial in West Java P. alata regenerated naturally with an average of 19 seedlings/m².

Pterygota is widespread but rare and occurs only locally, so is at serious risk of genetic erosion from habitat destruction.

The wood of Pterygota is of reasonable quality and may have potential for face veneer and as pulp for paper.

[40]All Nippon Checkers Corporation, 1989. Illustrated commercial foreign woods in Japan. Tokyo. 262 pp.
[61]Ashton, P.S., 1988. Manual of the non-dipterocarp trees of Sarawak. Vol. 2. Dewan Bahasa dan Pustaka, Kuala Lumpur. 490 pp.
[80]Balai Penjelidikan Kehutanan, 1950. Daftar ichtisar aturan berketjambah, penjimpanan dan pengiriman bidji dari beberapa djenis pohon dan pupuk hidjau [Tabular summary of the best ways to germinate, store and send seed of some tree and green manure species]. Laporan No 42. Balai Penjelidikan Kehutanan, Bogor. 23 pp.
[125]Bolza, E. & Kloot, N.H., 1966. The mechanical properties of 81 New Guinea timbers. Technological Paper No 41. Division of Forest Products, CSIRO, Melbourne. 39 pp.
[209]Corner, E.J.H., 1988. Wayside trees of Malaya. 3rd edition. 2 volumes. The Malayan Nature Society, Kuala Lumpur. 774 pp.
[267]Desch, H.E., 1941-1954. Manual of Malayan timbers. Malayan Forest Records No 15. 2 volumes. Malaya Publishing House Ltd., Singapore. 762 pp.
[300]Eddowes, P.J., 1977. Commercial timbers of Papua New Guinea, their properties and uses. Forest Products Research Centre, Department of Primary Industry, Port Moresby. xiv + 195 pp.
[304]Eddowes, P.J., 1995-1997. The forests and timbers of Papua New Guinea. (unpublished data).
[348]Forest Products Research Centre, 1967. Properties and uses of Papua and New Guinea timbers. Forest Products Research Centre, Port Moresby. 30 pp.
[360]Fundter, J.M. & Wisse, J.H., 1977. 40 belangrijke houtsoorten uit Indonesisch Nieuw Guinea (Irian Jaya) met de anatomische en technische kenmerken [40 important timber species from Indonesian New Guinea (Irian Jaya) with their anatomical and technical characteristics]. Mededelingen Landbouwhogeschool Wageningen 77-9. 223 pp.
[378]Goh, S.C., 1985. Research item: further strength properties of some Malaysian timbers. Malaysian Forester 48: 193-195.
[455]Hundley, H.G., 1986. List of trees, shrubs, herbs and principal climbers. Forest Department, Rangoon. 568 pp.
[464]Ilic, J., 1990. The CSIRO macro key for hardwood identification. CSIRO, Highett. 125 pp.
[487]Japing, C.H., 1961. Houtsoorten van Nieuw Guinea - literatuurstudie [Tree species of Dutch New Guinea - survey of literature]. 2 parts. Wageningen. 220 pp.
[536]Keating, W.G. & Bolza, E., 1982. Characteristics, properties and uses of timbers. Vol. 1. South-East Asia, northern Australia and the Pacific. Inkata Press Proprietary Ltd., Melbourne, Sydney & London. 362 pp.
[600]Kostermans, A.J.G.H., 1953. New and critical Malaysian plants I. Reinwardtia 2: 357-366.
[678]Lee, Y.H., Engku Abdul Rahman bin Chik & Chu, Y.P., 1979. The strength properties of some Malaysian timbers. Malaysian Forest Service Trade Leaflet No 34 (revised edition). Malaysian Timber Industry Board, Kuala Lumpur. 107 pp.
[758]Masano, 1987. Prospek perkembangan kayu asing di Indonesia [Prospects of exotic trees in Indonesia]. In: Soemarna, K. et al. (Editors): Prosiding diskusi pemanfaatan kayu kurang dikenal, 13-14 Januari 1987, Cisarua, Bogor. Badan Penelitian dan Pengembangan Kehutanan, Bogor. pp. 221-241.
[829]Ng, F.S.P., 1991-1992. Manual of forest fruits, seeds and seedlings. 2 volumes. Malayan Forest Record No 34. Forest Research Institute Malaysia, Kepong. 997 pp.
[831]Ng, F.S.P. & Mat Asri Ngah Sanah, 1991. Germination and seedling records. Research Pamphlet No 108. Forest Research Institute Malaysia, Kepong. 191 pp.
[888]Phengklai, C., 1995. Sterculiaceae. Thai Forest Bulletin (Botany) 23: 65-110.
[933]Research Institute of Wood Industry, 1988. Identification, properties and uses of some Southeast Asian woods. Chinese Academy of Forestry, Wan Shou Shan, Beijing & International Tropical Timber Organization, Yokohama. 201 pp.
[1023]Sjape'ie, I., 1954. Gewicht en volume van verschillende vrucht- en zaadsoorten [Weight and volume of various fruits and seeds]. Korte mededeling 20A. Bosbouwproefstation, Bogor. 10 pp.
[1038]Smitinand, T., 1980. Thai plant names. Royal Forest Department, Bangkok. 379 pp.
[1145]van Steenis, C.G.G.J., 1976. Miscellaneous botanical notes XXIV. Blumea 139-140.
[1169]Vidal, J., 1962. Noms vernaculaires de plantes en usage au Laos [Vernacular names of plants used in Laos]. Ecole française d'Extrême-Orient, Paris. 197 pp.
[1221]Whitmore, T.C. & Ng, F.S.P. (Editors), 1972-1989. Tree flora of Malaya. A manual for foresters. 4 volumes. Malayan Forest Records No 26. Longman Malaysia Sdn. Berhad, Kuala Lumpur & Petaling Jaya.
[1242]Wong, T.M., 1982. A dictionary of Malaysian timbers. Malayan Forest Records No 30. Forest Research Institute Malaysia, Kepong. 259 pp.

C. Phengklai

Pterygota alata
Pterygota horsfieldii

Phengklai, C., 1998. Pterygota Schott & Endl.. In: Sosef, M.S.M., Hong, L.T. and Prawirohatmodjo, S. (Editors): Plant Resources of South-East Asia No 5(3): Timber trees; Lesser-known 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:
Pterygota alata
Pterygota horsfieldii