Sindora (PROSEA Timbers)

Plant Resources of South-East Asia
Introduction

Protologue: Fl. Ind. Bat., Suppl. 1(2): 287 (1861).

Family: Leguminosae

Chromosome number: x= 12; S. wallichii: 2n= 24

Trade groups

Sepetir: medium-heavy hardwood, e.g. Sindora bruggemanii de Wit, S. coriacea Maingay ex Prain, S. supa Merr., S. velutina J.G. Baker, S. wallichii Graham ex Bentham.

Vernacular names

Sepetir

petir
Indonesia: sindur (general), sinampar (Banjarese), sasundur (Dayak, Kalimantan)
Malaysia: meketil, saputi (Peninsular), sampar hantu (Sarawak)
Philippines: supa, kayu galu
Thailand: makha-tae (central), kling, khaman (peninsular)
Vietnam: gụ, gõ.

Origin and geographic distribution

Sindora consists of about 20 species which are confined to Indo-China and western and central Malesia, except for one species which occurs in tropical Africa (Gabon). Sindora is absent from the Lesser Sunda Islands and New Guinea.

Uses

Sepetir timber occurs in two forms: attractively figured, and more uniformly coloured. The first is less common but is highly appreciated for high-class cabinets and furniture, panelling and other interior finishes and fancy articles. The sometimes streaked heartwood can be successfully peeled and sliced, yielding a very handsome veneer. The more uniformly coloured and less figured material is used for light indoor constructions such as solid panel doors, windows, door and window frames, ceilings and planking. It is a suitable timber for these purposes, because of its relatively low shrinkage, lack of degrade on drying, and small movement when dried. Other general uses of the more uniformly coloured timber are cabinet-making and the manufacture of household utensils and plywood. Sepetir is recommended as an attractive flooring timber to withstand light or sometimes normal pedestrian traffic as in residential buildings, hotels, hospitals, offices and shops. High quality and more heavy material of certain species is sometimes used for poles, joinery, and in heavy constructions like bridges and naval constructions. Low grade material is used for packing cases and pallets.

Many species yield a wood-oil which is used for making paints, varnishes and transparent paper, for caulking boats and adulterating other oils, for illumination and sometimes as a perfume. The wood-oil is sometimes used medicinally against skin diseases and rheumatism and applied as birdlime.

The oil of the seed of S. siamensis Teijsm. ex Miq. is sometimes used as a substitute for betel ( Areca catechu L.), while the fruits of S. sumatrana are widely used in local medicine against fevers, serious bleeding in the uterus and eczema on the head.

Production and international trade

The export of sawn sepetir timber from Peninsular Malaysia increased from 19 000 m³ (with a value of US$ 2.5 million) in 1984 to 53 500 m³ (with a value of US$ 6.9 million) in 1987. Thereafter, the amount of exported sepetir timber decreased to 33 000 m³ (worth US$ 5.7 million) in 1990, about 17 000 m³ (worth US$ 3.2 million) in 1991 and 8000 m³ (worth US$ 2.3 million) in 1992. The export of sepetir from Borneo is more important. For instance, the export of round logs of sepetir from Sabah in 1987 was 47 000 m³ (with a value of US$ 3.3 million at 68 US$/m³); in 1992 the export of logs was 12 000 m³ and of sawn timber 8500 m³ with a total value of US$ 2.6 million. Sepetir has some importance as an export timber in Indonesia and the Philippines, but export figures are not available.

Properties

Sepetir is a medium-weight hardwood. The colour of the heartwood is golden brown, darkening on exposure. Dark brown or black streaks are sometimes present, producing handsomely figured wood. The density is (450-)520-790(-900) kg/m³ at 15% moisture content. The grain is straight but more often shallowly interlocked, texture moderately fine and even.

For S. coriacea at 17% moisture content the modulus of rupture is c. 92 N/mm², modulus of elasticity 13 600 N/mm², compression parallel to grain 46 N/mm², compression perpendicular to grain 6 N/mm², shear 13.5 N/mm², cleavage 57 N/mm radial and 67 N/mm tangential, and Janka side hardness 5210 N.

The rates of shrinkage are medium: from green to 15% moisture content 1.5-2.0% radial and 2.9-5.4% tangential. The timber seasons moderately slowly with no degrade. It can be kiln-dried rapidly, but a mild schedule is recommended. Kiln schedule G (Malaysia) gives good results. Pre-drying before kilning is advised to reduce warping. Form stability of sepetir is good when dry.

The working properties of sepetir vary with the species. In general, stock inclines to be difficult to work. Conversion in a modern mill, however, presents little difficulty. Although the wood does not contain silica, the heartwood has considerable blunting effect on tools, but it usually can be worked to a smooth finish as long as knives are kept sharp. Air-dried sepetir is rated as difficult to saw and cross cut, but planes and bores easily into a smooth surface, and the moderately easy operation of turning produces usually a slightly rough surface. Sepetir is only moderately suitable for bending purposes. Finishing is satisfactory, but filling is required. Its resistance to splitting upon nailing is generally good but some species have pronounced tendency to split upon nailing and screwing, unless pre-bored. Gluing properties are very good.

Sepetir is rated as not to moderately durable; stake tests show an average service life in contact with the ground of only 2.6 years under tropical conditions. Under temperate conditions, the heartwood is rated as durable. As the timber is highly susceptible to powder-post beetle, termite and fungal attack, it should be treated with preservatives when it is not processed immediately. Sepetir is moderately difficult to treat with preservatives. An average absorption of 96 kg/m³ of a mixture of creosote and diesel fuel is obtained under standard open tank treatment. Using a 3% copper-chrome-arsenic solution and under the full-cell process, sepetir heartwood absorbs only 73 kg/m³ on average, whereas the average dry salt retention is only 2.2 kg/m³. The wood may be preserved very well when it is treated with 100% creosote, and has attained an absorption of 140 kg/m³. Attack by pinhole borers is very rare.

Minyak sepetir wood-oil from Malaysia has a clear light brown colour, a pleasant smell, and a gummy consistency. The specific gravity is 0.9657 and the optical rotation at 29° C is +27.8°. Distillation with steam gives 65% colourless volatile oil with an optical rotation of -6.5°. Supa wood-oil from the Philippines has a specific gravity of 0.9202 and optical rotation of -31.3°. It consists mainly of sesquiterpenes.

Description

Usually medium-sized but sometimes large, briefly deciduous trees of 20-35(-46) m tall with cylindrical bole having a diameter of up to 100(-180) cm, non-buttressed or flaring out at base or with steep thick buttresses; bark smooth, thin and brittle, rugulose with distant, prominent lenticels, dark purplish-grey and often green, brown or yellow flecked.
Leaves alternate, paripinnate, 2-8-jugate; leaflets shortly stalked, usually firmly leathery, often reticulately veined on both surfaces and slightly asymmetric, the midrib on the lower surface often ending in a gland.
Inflorescence made up of solitary or gregarious panicles, often velvety pubescent.
Flowers sessile or shortly pedicelled; calyx with a short tube, tawny velvety pubescent, and 4 lobes, usually unequal in size, with or without spinescent outgrowths; petal 1, fleshy in the lower half, with an indistinct, yellow or red claw; stamens (9-)10, 9 fused in hirsute sheath; ovary flat, hirsute at least along the suture, style recurved, stigma small.
Fruit a flat pod, circular to oblong, dehiscent with 2 valves, smooth but more often set with hollow spines.
Seeds 1-2, flat, hard and stony, black on top of a red or yellow aril about as large as the seed.
Seedling with epigeal germination; hypocotyl elongate; first two leaves alternate, leaflets larger and thinner than those of mature trees.

Wood anatomy

Macroscopic characters:

Heartwood distinctly demarcated from the lighter sapwood, pink-brown to shades of golden brown or red-brown, weathering to darker shades, often streaked with darker-coloured layers; sapwood light greyish-brown or beige with a pink tinge.
Grain shallowly interlocked.
Texture moderately fine and even or occasionally moderately coarse. Wood surface generally without significant lustre.
Growth rings distinct, produced by terminal layers of wood parenchyma; vessels commonly filled with deposits; parenchyma vasicentric, tending to aliform and in irregularly spaced apotracheal terminal bands; rays moderately fine, visible to the naked eye, in some species fairly prominent on a radial surface; wood containing characteristic vertical axial canals.
Ripple marks absent.

Microscopic characters:

Growth rings distinct and marked by terminal layers of wood parenchyma.
Vessels diffuse, 3-9/mm², solitary and in radial pairs and multiples of 2-4(-5), occasionally in clusters, sometimes solitary vessels or radial groups predominating, average tangential diameter 100-170(-220) μm; perforations simple; pits vestured, intervessel pits alternate, 4-8(-10) μm, vessel-ray and vessel-parenchyma pits similar but half-bordered; dark-staining gum-like deposits present; tyloses absent.
Fibres 1200-1400 μm long, non-septate in most species, but septate in S. beccariana, thin- to thick-walled, with simple to minutely bordered pits.
Parenchyma predominantly paratracheal, vasicentric, aliform to confluent, also diffuse and sometimes in terminal bands, in 1-2(-3)-celled strands.
Rays 6-11/mm, 2-3-seriate, maximum ray height 0.64 mm (Kribs type heterogeneous III).
Rhomboidal crystals in chambered cells, generally abundantly present but sometimes absent.
Vertical axial canals smaller than vessels present in some terminal layers of wood parenchyma.
All elements non-storied.

Species studied: S. beccariana, S. coriacea, S. echinocalyx, S. velutina, S. wallichii.

Growth and development

Sepetir trees are moderately fast to rather slow-growing. Trees of S. coriacea planted in Peninsular Malaysia reached an average diameter of 52 cm after 40 years, but trees of S. echinocalyx only 33 cm.

The trees are deciduous and may remain leafless for several weeks. Flowers appear shortly after the new leaves. Fruits take about 2 months to reach maturity. The waxy arils of the seeds are especially attractive to rodents, which disperse the seeds.

Other botanical information

The genus Sindora is well-defined and rather easy to recognize by its pubescent flowers with a single fleshy petal, its peculiar pods and arillate seeds. It belongs to the subfamily Caesalpinioideae and the tribe Detarieae. The timber of Copaifera palustris (Sym.) de Wit (synonym: Pseudosindora palustris Sym.) from Borneo has similar properties and uses and is often mixed with sepetir; it is called swamp sepetir.

Ecology

Sepetir trees occur generally scattered or sometimes gregarious (Borneo) in lowland dipterocarp forest on flat land and hillsides, up to 300 m altitude, but in Peninsular Malaysia sometimes up to 800 m. They generally favour well-drained soils, which are at least moderately fertile. They are, however, also found on sandstone, shales and volcanic soils (e.g. S. irpicina), sandy loam and clay soils (e.g. S. beccariana), as well as leached soils (e.g. S. coriacea).

Propagation and planting

Sepetir seeds survive for more than 3 years without any specific treatment. Germination is usually delayed. In germination tests without pretreatment of the seeds, after about 3 years only 20% of the seeds of S. echinocalyx had germinated. When the seed-coat is mechanically scarified on one or both sides of the seed, and the seeds are soaked in water at room temperature for 24 hours, the germination rate within one month is about 70%. A good method of mechanical scarification is to scrape off the protrusion of the seed-coat located next to the hilum. Treatment with dilute sulphuric acid or hot water is much less successful. However, seeds treated with concentrated sulphuric acid for one hour may give 80% germination.

For seedlings of S. supa a sand-humus mixture (1 : 1) appeared to be the most satisfactory potting medium. Average height of seedlings after 7 months is about 20 cm when potted in this mixture, and the seedlings have a high shoot to root ratio (about 3.8). A mixture of ordinary garden soil and sand (2 : 1) gives slightly less good results.

Silviculture and management

In logged-over forest the regeneration of sepetir is often abundant. Usually the number of seedlings in logged-over forest is larger than in undisturbed forest, similar to e.g. keruing (Dipterocarpus spp.). From Peninsular Malaysia an average of one large tree (over 60 cm in diameter) per 5 ha of undisturbed forest is reported; locally sepetir is more common, up to one large tree per 2 ha.

Harvesting

Sepetir logs are usually free from defects after felling. Wood-oil was formerly obtained by hacking the trunk and cutting cavities in its base. Subsequently the flow of oil was increased by firing. This destructive method of harvesting wood-oil was practised in the Philippines, Indonesia and Malaysia.

Yield

As sepetir trees occur scattered in natural forest, the yield of timber per ha is often comparatively low. A freshly cut tree of S. supa in the Philippines may yield about 10 litres of wood-oil.

Genetic resources

Most Sindora species are uncommon and occur scattered. Large-scale exploitation of forest, as practised in many places, may seriously threaten these species with extinction, except when the felling cycle is long enough to allow new trees to reach maturity in sustainably managed forest. Extensive planting of sepetir trees is not practised.

Prospects

As very little information about sepetir is available, particularly about silvicultural aspects, growing rates and the occurrence of streaked wood, which is highly valued for decorative purposes, more research on these aspects is urgently needed. S. coriacea has been suggested as a species suitable for enrichment planting in logged-over forest, but this should be further investigated.

Literature

Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department, Sabah, Sandakan. pp. 375-382.
Cockburn, P.F., 1976. Trees of Sabah. Vol. 2. Forest Department Sabah, Kuching. pp. 177-183.
de Wit, H.C.D., 1949. Revision of the genus Sindora Miquel (Legum.). Bulletin of the Botanic Gardens, Buitenzorg, ser. 3, 18: 5-82.
Hidayat, E., 1979. Sindora, jenis kayu penghasil resin [The resin-producing Sindora]. Buletin Kebun Raya 4(2): 67-69.
Ho, K.S., 1982. Malaysian timbers - sepetir. Malaysian Forest Service Trade Leaflet No 60. Malaysian Timber Industry Board, Kuala Lumpur. 9 pp.
Lasmarias, V.T., 1979. Survival and growth of akle (Albizzia acle (Blanco) Kosterm.) and supa (Sindora supa Merr.) in various potting media. Sylvatrop Philippine Forest Research Journal 4(3): 161-166.
Malaysian Timber Industry Board, 1986. 100 Malayan timbers. Kuala Lumpur. pp. 196-197.
Sabariah, A., 1978. Pretreatment of Dialium (keranji) and Sindora (sepetir) seeds to promote germination. Malaysian Forester 41: 26-28.
Sasaki, S., 1980. Storage and germination of some Malaysian legume seeds. Malaysian Forester 43: 161-165.
Whitmore, T.C., 1972. Leguminosae. In: Whitmore, T.C. (Editor): Tree flora of Malaya. A manual for foresters. Vol. 1. Longman Malaysia SDN Berhad, Kuala Lumpur. pp. 270-273.

Selection of species

Authors

E.N. Sambas (general part),
P.B. Laming (properties),
Ani Sulaiman (wood anatomy),
M.S.M. Sosef (selection of species)