Calophyllum (PROSEA Timbers)

Plant Resources of South-East Asia
Introduction

Protologue: Sp. pl.: 513 (1753); Gen. pl. (ed. 5): 229 (1754).

Family: Guttiferae

Chromosome number: x= unknown; C. inophyllum: 2n= 32

Trade groups

Bintangor: lightweight to medium-heavy timbers, e.g. Calophyllum calaba L., C. inophyllum L., C. papuanum Lauterb., C. pulcherrimum Wallich ex Choisy, C. soulattri Burm.f., C. teysmannii Miq.

The timber of C. inophyllum is often traded separately as "beach calophyllum".

Vernacular names

Bintangor

Indonesia: bintangur
Malaysia: penaga (Peninsular, Sabah), bakakol, entangor (Sarawak)
Papua New Guinea: calophyllum
Philippines: bintanghol
Burma: tharapi, poon
Thailand: krathing (central), tanghon-baiyai (Surat Thani)
Vietnam: mù u, cồng.

Origin and geographic distribution

Calophyllum is a very large genus comprising about 190 species. Most of the species are found in the Indo-Malesian region, Micronesia, Melanesia and northern Australia. Only approximately 8 species occur in Central and South America; about 20 occur in Madagascar and surrounding islands. Peninsular Malaysia, Sumatra, Borneo and New Guinea are very rich in species, about 40, 35, 65 and 35, respectively. New Guinea has the largest proportion of endemic species, about 75%. Some species are widespread, e.g. C. calaba (Sri Lanka and Indo-China to central Malesia and northern Australia), C. soulattri (Indo-China and Thailand, through the whole of Malesia, to northern Australia and Melanesia), and C. inophyllum (eastern Africa and Madagascar, India to northern Australia and Polynesia). The latter species is often planted as an ornamental within its range and also in western Africa and tropical America.

Uses

Bintangor is a good general purpose timber. It is suitable for light construction, flooring, moulding, decking, panelling, joinery, furniture, veneer and plywood, wooden pallets, boat construction and diving boards. In several regions the wood is much sought after for masts, spars, bridge work and scaffolding because of the tall slender forms of the poles of several species. Sometimes the wood is also used for cartwheels and axles, musical instruments and blowpipes. Heavier wood is sometimes used for beams and columns, for railway carriages and crane shafts. Timber of C. papuanum and C. pauciflorum from Papua New Guinea is considered a decorative substitute for dark-coloured mahogany if suitably stained, and for all kinds of mahogany if transparently coated. It is also sometimes considered a good substitute for dark red meranti.

The poisonous latex from the bark of several species is used to stupefy fish and, mixed with rice, to kill rats. A decoction of the bark and the latex of some species (e.g. C. inophyllum) is used medicinally, internally against diarrhoea and after childbirth, externally against skin and eye diseases and rheumatism; leaves, flowers and seeds are sometimes also used in local medicine. The fruits of some species are edible but often sour. Usually they are pickled, but caution is necessary as they contain toxins. The oil from the seeds is sometimes used as illuminant and in soap making. The seed-oil and the latex from the bark have occasionally been used in dyeing "batik" cloth in Java. A decoction of the bark (e.g. of C. inophyllum) is sometimes used to toughen and dye fishing-nets. C. inophyllum is commonly planted as an ornamental.

Production and international trade

In several areas (e.g. Peninsular Malaysia, Borneo, New Guinea) bintangor may be very abundant and of considerable importance for its timber. The timber is exported in fairly large quantities to Japan, especially from Borneo and New Guinea. The export of round logs from Sabah in 1987 was 42 000 m³ with a value of US$ 2.8 million and in 1992 17 500 m³ of logs and 41 500 m³ of sawn timber with a total value of US$ 10.3 million. In Papua New Guinea Calophyllum timber is ranked in the MEP (Minimum Export Price) group 1 and fetched a minimum export price of US$ 80/m³ for saw logs in 1992.

Properties

Bintangor is a light to medium-weight, moderately hard wood. The heartwood is red-brown, pink-brown or orange-brown. The sapwood is yellow-brown with a pink tinge and well defined. The density is (400-)450-850(-900) kg/m³ at 15% moisture content (average 680 kg/m³). The grain is interlocked, spiral or wavy, texture moderately coarse to coarse and uneven.

At 15% moisture content the modulus of rupture is 48-94 N/mm², the modulus of elasticity 7550-15 300 N/mm², compression parallel to grain 37-55 N/mm², compression perpendicular to grain 3-4 N/mm², shear (5-)6-9 N/mm², cleavage 44-60 N/mm radial and 58-72 N/mm tangential, Janka side hardness 2580-4820 N and Janka end hardness 4090-6050 N.

The rates of shrinkage are medium, from green to 15% moisture content 1.4-2.1% radial and 2.0-3.7% tangential, from green to oven dry 3.9-4.4% radial and 5.3-6.3% tangential. Drying is easy to moderately difficult; some seasoning degrade may occur. Generally bintangor timber seasons fairly slowly with moderate defects such as end checking, splitting, cupping and springing. The rate of drying is rather similar to light red meranti. It takes about 2.5-3.5 months to air dry 25 mm thick boards, and 4-5 months for 40 mm thick boards. Weighting down of stacks during air drying is recommended as this will reduce the tendency of the timber to warp and twist. Mild kiln schedules are required in drying. In Malaysia kiln schedule C is considered most suitable. Kiln drying of 25 mm thick boards from 50% to 10% moisture content takes approximately 8 days under favourable conditions, but in Papua New Guinea a kiln drying time of 5 days for flat grain and 6 days for edge grain has been reported for 27.5 mm thick boards of wood from C. vexans.

The sawing properties are rated as good; the timber is non-siliceous. For timber from Papua New Guinea, a normal ripping saw having 24 teeth with a 20° rake angle is satisfactory, whereas for cross cutting, a saw with crosswise sharpened teeth with 20° rake angle can be used. Bintangor is generally easy to bore but sometimes liable to burning in boring and mortising. Planing is usually easy and the planed surface is smooth to moderately smooth, but sometimes the wood is difficult to plane because of strongly spiral or interlocked grain. When the grain is properly filled, the timber takes a high polish. The nailing properties are rated as moderate to poor, but as satisfactory for Papua New Guinea timbers. Bintangor timber can be peeled without pretreatment at a 90peeling angle to produce good veneer. For instance, C. vexans from Papua New Guinea produces a good-quality veneer with no woolly surface; it dries well with a tangential shrinkage of 6%, and it glues well with a bond strength of 1.5 N/mm² for phenolic and 1.6 N/mm² for urea resin. Bintangor veneer glued with urea formaldehyde extended with 20% wheat gives plywood of good quality. However, the veneering qualities of C. apetalum Willd. from India and C. tomentosum Wight from Sri Lanka have been found to be unsatisfactory. Bintangor may produce a high grade particle board and hardboard with good water resistance (e.g. C. vexans in Papua New Guinea). Paper and pulping qualities of C. vexans are also rated as good.

Most bintangor timber is rated as moderately durable or non-durable under exposed conditions. Stake tests showed an average service life in contact with the ground of 0.5-2 years under tropical conditions. However, the timber from some species is rather more durable. Graveyard tests in Indonesia showed an average service life in contact with the ground for wood of C. pulcherrimum of 3.5 years. The resistance to wood-rotting fungi varies from good to very poor. The heartwood is fairly resistant to preservative treatment, and absorbs only about 65 kg/m³of preservative using an open tank system.

The timber of C. inophyllum differs from this description in several characteristics. It is often heavier, stronger and more durable, more difficult to saw, and sawn surfaces tend to be woolly. It is recommended not to use this timber for lengths over 3 m because it is often bent.

The wood of C. inophyllum contains 58% cellulose, 31.5% lignin, 17% pentosan and no silica. The solubility is 4.4% in alcohol-benzene, 1.0% in cold water, 4.5% in hot water and 12.4% in a 1% NaOH solution. The energy value is about 19 100 kJ/kg.

The main compounds of the seed oil are oleic, linoleic, stearic and palmatic acid. Tannins are commonly present, especially in the bark but often also in the leaves. Saponins and cyanogenetic glucosides have been reported to occur in the leaves of some species (e.g. C. inophyllum).

A considerable variety of xanthones is found in the wood and bark. One of the xanthones, called jacareubin, is nearly always present in Calophyllum but is extremely rare outside this genus. The latex is very rich in complex coumarin derivates, some of which are piscicidal, while others are insecticidal.

Description

Evergreen trees, rarely shrubs, up to 40(-60) m tall, with sticky latex either clear or opaque and white, cream or yellow; bole often straight and cylindrical, but occasionally twisted (C. inophyllum), up to 100(-240) cm in diameter; buttresses usually absent, rarely small, some species with stilt or loop roots; outer bark often with characteristic diamond to boat-shaped fissures becoming confluent with age, smooth, often with a yellowish or ochre tint, inner bark usually thick, soft, firm, fibrous and laminated, pink to red, darkening to brownish on exposure; crown evenly conical to narrowly hemispherical; twigs more or less flattened and angled, usually with naked, often elongate terminal buds.
Leaves decussate, simple and entire, leathery, glabrous and petiolate, with closely parallel secondary venation alternating with latex canals which are usually less prominent; stipules absent.
Inflorescences terminal or axillary, racemose, branched or simple, (1-)3-many-flowered and usually with small, deciduous bracts.
Flowers usually bisexual, but sometimes functionally unisexual, sweetly scented, with perianth of 4-16 tepals in several whorls, usually whitish; stamens numerous, with filaments usually only slightly connate at base and with small basifixed anthers dehiscing by long, lateral slits; pistil 1, with unilocular ovary having a single, basal ovule, one style and often a peltate stigma.
Fruit a drupe, with pericarp consisting of an exocarp, a fleshy to fibrous mesocarp and a stony endocarp (stone); outer layer (exocarp + mesocarp) often with large air spaces; stone with a hard layer and often with a spongy layer, containing a single seed.
Seed with large cotyledons and radicle pointing to the base of the fruit; endosperm absent.
Seedling with cryptocotylar germination (cotyledons remaining enclosed in stone) and short epicotyl; seedling leaves opposite, sometimes first two pairs of leaves pseudo-verticillate or lowest pairs of seedling leaves small and soon falling off.

Wood anatomy

Macroscopic characters

Sapwood yellow-brown with a pink tinge and well defined from the heartwood, which is red-brown, pink-brown or orange-brown.
Grain interlocked, spiral or wavy.
Texture moderately coarse to coarse and uneven; planed surface very lustrous; stripe figure present on radial surface and darker coloured zig-zag markings on tangential surface.
Growth rings usually inconspicuous but sometimes marked by zones of denser wood or by narrow bands of parenchyma tissue.
Vessels visible to the naked eye, mostly solitary but arranged in irregularly radial chains.
Parenchyma distinct in narrow, widely spaced, dark-coloured lines.
Rays very fine and not distinct to the naked eye; end surfaces dull.

Microscopic characters

Growth rings usually inconspicuous but sometimes marked by zones of denser wood or by narrow parenchyma bands.
Vessels diffuse, (1-)2-9(-12)/mm², almost exclusively solitary, in a marked diagonal to radial pattern, round to oval, average tangential diameter 100-200μm; perforations simple; intervessel pits alternate, round to oval, 2-6μm; vessel-ray pits vertically to horizontally elongate and simple; vessel-parenchyma pits half-bordered or with reduced borders, sometimes almost simple; helical thickenings absent; tyloses sometimes present.
Vasicentric tracheids present.
Fibres 0.4-1.4 mm long, non-septate, thin- to thick-walled, variable within and between species, with minutely bordered or simple pits confined to the radial walls.
Parenchyma in (1-)4-5(-9) cells wide, often widely spaced, continuous or irregularly broken apotracheal bands.
Rays 8-17/mm, 1-2-seriate, mostly uniseriate, but a varying number of biseriate rays also present, much less than 1 mm high, usually composed of both upright and procumbent cells, heterogeneous (Kribs type IIB).
Prismatic crystals present in ray and axial parenchyma cells in some species. Silica absent.
Reddish-brown deposits present in ray cells.

Growth and development

At germination the radicle breaks through on one side of the base of the stone in the majority of species. In species with a thin stone wall, the radicle may emerge as soon as 10 days after the fruit falls to the ground. In species with a thick stone wall this may take 3 months. Usually the seedling shows intermittent growth. The terminal bud of the sapling is usually functional and growth is monopodial, but sometimes sympodial. All leaves are fully expanded and often very large, and each pair of leaves is separated by a well-developed internode.

Growth of the young trees appears to be discontinuous and branching is rhythmic. The trunk and the branches are orthotropic. Older trees generally show sympodial growth; usually each innovation consists of several pairs of leaves, but sometimes it has only a single pair. Sometimes the first pairs of leaves of the axillary innovations are reduced to scales with very short internodes.

Little is known about the developmental stages between the young plant and the flowering and fruiting adult plant. Data from a few sample plots in Peninsular Malaysia indicate that growth may be rather slow, and that trees may take about 70 years to attain a diameter of 50 cm. However, there is reason to believe that growth may be considerably faster under favourable conditions.

The flowers are insect-pollinated, e.g. by bees. It has been suggested that apomixis may occur in Calophyllum, resulting in polyembryony; the occurrence of up to 6 embryos forming a close-knit mass instead of the normal single embryo has been reported. Hybridization may occur, often with C. inophyllum as one of the parents.

Trees often bear fruits throughout the year. The fruits are eaten and dispersed by mammals (bats, squirrels, monkeys) and birds. However, the fruits of some species are dispersed by water.

Other botanical information

The immediate relatives of Calophyllum in South-East Asia are Mammea and Mesua. These 3 genera are usually placed in the subfamily Calophylloideae and tribe Calophylleae together with some small genera of Madagascar and India. Calophyllum is easily distinguishable by its single basal ovule and particularly by its nearly always strictly parallel and close venation of the leaves.

All Calophyllum species look very similar. Only close examination of comparatively small differences in leaf, twig, bud, inflorescence and fruit enables species to be distinguished. Floral characteristics are of less use for determination, except sometimes the size of the flowers, the number of whorls of tepals, and the indumentum of the outer tepals. Several floral characteristics are variable in some species, and their diagnostic use is limited by the paucity of available herbarium material at anthesis and the often considerable distortion that occurs on drying. Characters of the living tree, especially the bark, the colour of the exudate, and the habitat are useful for distinguishing species, and with some experience Calophyllum species are probably easier to identify in the forest than from herbarium specimens.

Most species are already recognizable when very young, as they show different growth patterns in their initial stages, and differ in leaf shape, size and colour.

The timber of C. brasiliense Cambess. is important in South and Central America and traded as "Santa Maria" or "jacareuba". Timber of Calophyllum species from Madagascar is known as "vintanina", and that of the Indian C. polyanthum Wallich ex Choisy as "poon".

Ecology

Calophyllum is a genus of lowland tropical rain forest from the seashore to more inland, but a few species occur in montane rain forest. Only a few species grow in drier or more open habitats; C. inophyllum is a species of sandy beaches. Some species (e.g. C. canum, C. pisiferum, C. sil, C. soulattri, C. teysmannii and C. venulosum) show considerable morphological variation, which is at least partly correlated with their wide ecological ranges. Most species, however, have a rather restricted ecological range; many grow in more or less well-drained, mixed dipterocarp forest, some prefer stream sides (e.g. C. macrocarpum) whereas others grow most commonly in forests on acid soils (e.g. C. nodosum, C. obliquinervium). A group of species occurs in hill forest up to 1300 m altitude (e.g. C. collinum, C. exiticostatum, C. papuanum and C. symingtonianum), and some species even occur predominantly above 1300 m (e.g. C. garcinioides, C. pauciflorum). Still others prefer peat swamps or periodically inundated forest (e.g. C. suberosum). In some areas, e.g. Johor (Peninsular Malaysia) and around Kuching (Sarawak), several Calophyllum species grow together in swamp forests. Elsewhere there may be concentrations of species in ridge forests (throughout Malesia) and in mixed lowland forests (e.g. in Papua New Guinea).

Locally, some species may be abundant, e.g. C. sundaicum and C. scriblitifolium, having an average of 1.5 trees or even more (up to 5.5) per ha in peat-swamp forest in Peninsular Malaysia. In lowland and lower montane forest, bintangor trees often reach to the top of the main canopy at maturity, but are not emergent.

Propagation and planting

Natural regeneration usually occurs near the mother tree. Seedlings grown in nurseries require shade. In plantation trials in Indonesia the spacing of seedlings is usually 2 m × 3 m.

Silviculture and management

The selective cutting system and removal of undesirable trees can enhance the natural regeneration of bintangor.

Diseases and pests

Leaves and young shoots are susceptible to attack by various insects.

Harvesting

The main defects of logs are slight spongy heart and pinhole borer damage, but generally the logs are sound.

For seed-oil extraction, the seeds are shelled, chopped, dried, pounded and then boiled. The oil is skimmed from the top of the boiling water. The seeds may also be crushed to a paste and the oil is then drained off.

Genetic resources

In several areas bintangor is abundant, e.g. in dry lowland forest and particularly in peat-swamp forest in Peninsular Malaysia. In Borneo and New Guinea several species are also common and widespread. In many other areas bintangor is much less common and occurs scattered in the forest. When bintangor timber becomes more popular, the rarer species will become liable to genetic erosion.

Prospects

The timber of Calophyllum is expected to be more fully utilized in the future in view of decreasing supplies of more popular and expensive timbers such as red meranti (Shorea spp.). Bintangor often produces rather decorative figures on flat-sawn boards, and the distinctive colours of the timber are attractive for decorative purposes, such as furniture, parquet flooring, solid door construction, and for veneer and plywood. If properly promoted, Calophyllum timber from South-East Asia could become as popular as that from South and Central America ("Santa Maria") or India ("poon").

Research on all silvicultural aspects is urgently required to ensure a continuous supply of bintangor. Research on handling of the timber after harvesting is also important to support its marketability. More detailed information on working properties, drying, preservative treatment and mechanical properties is required to enhance the usability of the timber.

Literature

Abdul Rashid A. Malik, 1984. Malaysian timbers - bintangor. Malaysian Forest Service Trade Leaflet No 89. Malaysian Timber Industry Board, Kuala Lumpur. 7 pp.
Balan Menon, P.K., 1971. The anatomy and identification of Malaysian hardwoods. Malayan Forest Records No 27. Forest Research Institute Malaysia, Kepong. 124 pp.
Chudnoff, M., 1979. Tropical timbers of the world. USDA, U.S. Forest Products Laboratory, Madison, Wisconsin. p. 577.
Eddowes, P.J., 1977. Commercial timbers of Papua New Guinea, their properties and uses. Forest Product Research Centre, Department of Primary Industry, Port Moresby.
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. pp. 60-63.
Martawijaya, A., Kartasujana, I., Kadir, K. & Prawira, S.A., 1986. Indonesian wood atlas. Vol. 1. Forest Products Research and Development Centre, Bogor. pp. 23-28.
Meniado, J.A., Tamolang, F.N., Lopez, F.R., America, W.M. & Alonzo, D.S., 1975. Wood identification handbook. Vol. 1. Government Printing Office, Manila. pp. 128-133.
Stevens, P.F., 1980. A revision of the old world species of Calophyllum (Guttiferae). Journal of the Arnold Arboretum 61: 117-699.
Timber Research and Development Association, 1979. Timbers of the world. Vol. 1. The Construction Press, Lancaster. pp. 357-358.
Whitmore, T.C., 1983. Guttiferae. In: Whitmore, T.C. (Editor): Tree flora of Malaya. 2nd edition. Vol. 2. Malayan Forest Records No 26. Longman Malaysia SDN Berhad, Kuala Lumpur. pp. 162-196.

Selection of species

Authors

S.C. Lim (general part, properties, wood anatomy),
R.H.M.J. Lemmens (selection of species)