Pericopsis (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Pericopsis Thwaites

Protologue: Enum. Pl. Zeyl.: 413 (1864).

Family: Leguminosae

Chromosome number: x= unknown

Trade groups

Pericopsis: heavy hardwood, a single species within South-East Asia, Pericopsis mooniana (Thwaites) Thwaites, Enum. Pl. Zeyl.: 413 (1864), synonyms: Ormosia villamilii Merr. (1915), Pericopsis ponapensis (Hosok.) Hosok. (1943).

Vernacular names

Pericopsis:

• nandu wood, nedun tree (En)
• Indonesia: kayu kuku (general), kayu besi papus (Sulawesi), nani laut (Irian Jaya)
• Malaysia: kayu laut (Peninsular, Sabah), merbau laut (Peninsular)
• Philippines: makapilit (Bisaya).

Origin and geographic distribution

Pericopsis consists of 5 species, 4 of which are confined to tropical Africa. P. mooniana has a large area of distribution and is found in Sri Lanka, Peninsular Malaysia, southern Sumatra, eastern Borneo (Sabah, East Kalimantan), the Philippines (Mindanao), Sulawesi, the Moluccas, New Guinea and Micronesia (Jap, Palau, Ponape).

Uses

Pericopsis timber is very handsome. It has decorative uses and is used as a substitute for teak for cabinet work, furniture, turnery, high-quality joinery, parquet flooring, shop fittings, panelling and veneer. It is also suitable for heavy construction purposes, and is used in ship building (especially for rails and decks), for bridges, door and window frames, vehicle bodies and in freshwater engineering. The wood can probably be used successfully in saltwater harbour works, but resistance to teredos has not yet been tested experimentally.

Production and international trade

This decorative wood is very valuable. It fetches high prices on the world market and is ranked in Indonesia among other fancy woods such as sandalwood (Santalum' album L.), ebony (Diospyros celebica Bakh.) and sawo kecik (Manilkara kauki (L.) Dubard). However, supplies of this timber are very limited, and trade and export are negligible. Export from Indonesia is probably mainly to Japan.

Properties

The wood is moderately heavy to heavy and hard. The heartwood is yellowish-brown when fresh, turning to golden brown to dark brown upon exposure, usually with irregular darker streaks. The sapwood is light yellowish-brown, distinctly demarcated from the heartwood. The density is (650-)780-900 kg/m³ at 12% moisture content. The grain is interlocked, texture fine to moderately coarse.

At 12% moisture content, the modulus of rupture is 151 N/mm², modulus of elasticity 16 100 N/mm², compression parallel to grain 90 N/mm², compression perpendicular to grain 10-12 N/mm², shear 14-15 N/mm², Janka side hardness 8900-9000 N, and Janka end hardness 10 600 N. See also the table on wood properties.

Pericopsis wood should be dried slowly and carefully. Close stacking during air drying is advised. Shrinkage rates are medium (from green to 12% moisture content 2-4% radial and 4-7% tangential, from green to oven dry 3-5% radial and 5-8% tangential). Deformation during drying is slight, however. The timber kiln dries satisfactorily. Once dry, the wood is rated as stable.

The wood is fairly easy to work, although sharp saws are needed. There is a slight tendency to picking up of grain, but this can be obviated by cutting at an acute angle. When the grain is properly filled, the wood polishes and turns well. The holding power of nails and screws is good, but pre-boring is advisable as the wood is hard and is liable to splitting. Gluing gives no problems. Surfaces may have patchy discolorations; treating with synthetic oils and varnishing, or painting, solves this problem (the wood takes varnish and paint well).

The timber is durable, also in contact with the ground or when exposed to the weather. It is rated, however, as slightly susceptible to powder-post beetles. Laboratory tests in Indonesia showed that the wood is moderately resistant to dry-wood termites and that the resistance to wood-rotting fungi varies from poor to very good. It is moderately easy to treat with preservatives, the sapwood more easily than the heartwood. The average retention of heartwood is 226 l/m³ to creosote oil, 182 l/m³ to coppernaphtenate, and 16 kg/m³to 4% sodiumfluoride.

Description

• Medium-sized to fairly large trees, up to 40 m tall, with bole straight or twisted, branchless for up to 20 m but often less, up to 80(-100) cm in diameter, shallowly grooved or slightly fluted at base; bark soft and thin, reddish, flaking in thin plates.
• Leaves alternate, imparipinnate, 5-8-foliolate; leaflets alternate or rarely subopposite, ovate to elliptical, 4-9 cm × 2.5-5 cm, rounded at base, acute to broadly acuminate at the top, glabrous, with about 7 pairs of secondary veins; stipules early caducous, stipels minute or absent.
• Inflorescence racemose or paniculate, axillary or terminal, bracts and bracteoles minute, very early caducous.
• Flowers bisexual, about 2 cm long; calyx bell-shaped, about 15 mm long, appressed pubescent outside, tomentellous inside, with 5 acute lobes, two slightly shorter than the other three, and connate for most of their length; corolla papilionaceous, keel petals partly connate, wings auriculate, glabrous, dark purple; stamens 10, equal, free, anthers small, ellipsoid to oblong, dorsifixed; ovary stipitate, 1-6-ovuled, pubescent along the margin, style with a hooked apex and a small terminal stigma; disk present at base of ovary.
• Fruit a slightly woody, oblong pod, flat, indehiscent, stipitate with a narrow base, beaked at the tip, winged along margin, glabrous, sometimes constricted near the middle.
• Seeds large, flat, rounded to elliptical, reddish-brown, with apical orbicular hilum.
• Seedling with epigeal germination.

Wood anatomy

Macroscopic characters

• Heartwood yellowish-brown when fresh, turning to brown, dark brown or dark golden brown upon exposure, usually with irregular darker streaks, demarcated distinctly from the light yellowish-brown sapwood; white coloured deposits in vessels often visible.
• Grain distinctly interlocked.
• Texture fine to moderately coarse.
• Growth rings often vaguely discernible; ripple marks distinct but fine.

Microscopic characters

• Growth rings, if discernible, marked by marginal, interrupted parenchyma bands and/or a slight difference in vessel diameter and/or in fibre wall thickness on either sides of the ring boundary and/or periodical variation in the length of confluent parenchyma from early to late wood.
• Vessels diffuse, (6-)8-13/mm², usually solitary and in radial multiples of 2-3(-4), rarely in clusters, 108-160μm in tangential diameter; perforations simple; intervessel pits alternate, vestured, 6-8 μm in diameter; vessel-ray and vessel-parenchyma pits usually almost similar to intervessel pits, rarely palisade-like and simple; tyloses infrequent.
• Fibres 1.0-1.7 mm long, thick-walled (walls c. 3.5 μm thick), pits infrequent, with minute borders, confined to the radial walls.
• Parenchyma winged-aliform to confluent, connecting a few vessels, apotracheally diffuse-in-aggregates, and sometimes in interrupted bands at the ring boundary, usually in 2-3(-4)-celled strands.
• Rays 7-9/mm, (1-)2-3(-4)-seriate, 100-280 μm high, homocellular (Kribs type homogeneous).
• Prismatic crystals present in chambered axial parenchyma, in long chains sometimes of more than 20 chambers; aliform and confluent parenchyma usually containing crystals in their outer layers.
• All elements storied.

Growth and development

Seedlings grow slowly; in nurseries a total growth of 2 cm is reported for the first two months of growth in the shade and only 0.5 cm per month in the open. After 4 years, the average height of plants grown from seeds from Sri Lanka in the Philippines was 1.9 m. Trees grown in West Java, also from seeds from Sri Lanka, started to flower and bear fruits when 10 years old. They do not flower and fruit every year. The flowering time in West Java is December to February and the fruits ripen from April to July. P. mooniana is known to nodulate well, and its ability to supply its own nitrogen gives the tree a notable advantage.

Other botanical information

Pericopsis was considered to be a monotypic South-East Asian genus until it was pointed out that the African genus Afrormosia should be merged with the former. Others prefer to keep the two genera separated on the basis of the stipels being absent in Pericopsis and present in Afrormosia. Stipels are, however, present in collections of Pericopsis mooniana from Sri Lanka and Sumatra. The merging of the two genera is consolidated by phytochemical research.

The genus Pericopsis s.l. is closely related to Ormosia from tropical South-East Asia and tropical America, and to Haplormosia from tropical Africa. It differs from the first by the presence of a disk and auriculate wings and keel, and from the second by the dorsifixed anthers and also the auriculate wings and keel.

Ecology

P. mooniana grows primarily scattered in coastal forests, but can be found along river banks and in periodically inundated forest up to 200(-350) m altitude. It occurs in evergreen or semi-deciduous forest, primarily on sandy regosols which are relatively infertile. The species requires an annual rainfall of 750-2000 mm and occurs in more seasonal conditions with 3-4 dry months (monthly precipitation less than 60 mm). In south-eastern Sulawesi P. mooniana is found in association with Actinodaphne glomerata Nees, Calophyllum soulattri Burm.f., Dehaasia curtisii Gamble and Metrosideros petiolata Koord.

Propagation and planting

Seeds have no dormancy period, and germinate well (about 87%) when sown soon after collection. The seeds quickly lose viability and cannot be stored for more than 3 months unless they are stratified, which may prolong storage of viable seeds up to 6 months. P. mooniana can also be propagated easily from stem cuttings.

Application of growth hormones may increase the growth of seedlings; a GHB solution of 3 ml/l water gives good results. Seedlings are usually planted from the nursery into the field when 16-20 cm high and having 5-7 leaves. Usually, all the leaves are stripped off and the leader shoot and taproot are cut back before the seedlings are transplanted. When using wildlings, the best results have been obtained with plants 30-40 cm tall.

Diseases and pests

Seedlings often suffer from damping-off disease. In nurseries, seeds are reported to be damaged by the large cricket species Brachytrypes portentosus.

Harvesting

In Indonesia trees are harvested according to the Indonesian selective felling and planting system, with a diameter limit of 50 cm. The logs are sinkers, so cannot be floated down the river. Wood dust may irritate eyes and throat. Potentially hazardous sharp splinters may be released from the wood during sawing.

Genetic resources

P. mooniana is an uncommon species. Since natural regeneration is scarce and large-scale exploitation has not been followed by replanting, this species is at risk of being endangered. In many areas it is rare and considered vulnerable, e.g. in Peninsular Malaysia, Kalimantan, Sulawesi and Sri Lanka. Only locally are there stands of at least some importance, e.g. in western Irian Jaya, western Papua New Guinea and South Sulawesi. In 1962 the standing volume in western Irian Jaya was estimated at 600 000 m³.

Prospects

P. mooniana yields a valuable timber. However, the species urgently needs protection. It was proposed in 1992 for inclusion in Appendix II of the CITES convention. All trade of species included in Appendix II must be registered. Plantations may be established fairly easily, but more research on silvicultural aspects is urgently needed.

Literature

• Brummitt, R.K., 1970. Notes on two South-East Asian species of Leguminosae, Cathormion umbellata and Pericopsis mooniana. Kew Bulletin 24: 231-234.
• Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department, Sabah, Sandakan. pp. 384-385.
• Dahms, K.-G., 1982. Asiatische, Ozeanische und Australische Exporthölzer [Asiatic, Pacific and Australian export timbers]. DRW-Verlag, Stuttgart. pp. 172-173.
• Daryono, H., 1986. Pengaruh penggunaan zat pendorong tumbuh tanaman terhadap pertumbuhan dan jumlah daun bibit kayu kuku (Pericopsis mooniana Thw.) dan sawo kecik (Manilkara kauki Dubard) [Effects of applied growth regulators on growth and leaf number of kayu kuku (Pericopsis mooniana Thw.) and sawokecik (Manilkara kauki Dubard)]. Buletin Penelitian Hutan No 486: 9-20.
• 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: 109-113.
• Jakovlev, G., 1971. Notae de genere Pericopsis Thwaites (Incl. Afrormosia Harms). Novitates Systematicae Plantarum Vascularum 8: 177-181.
• National Academy of Sciences, 1979. Tropical Legumes: resources for the future. National Academy Press, Washington, D.C. pp. 214-215.
• Verdcourt, B., 1979. A manual of New Guinea legumes. Botany Bulletin No 11. Office of Forests, Division of Botany, Lae. pp. 285-287.
• Wardani, M. & Sidiyasa, K., 1989. Pengaruh tinggi cabutan dan perlakuan akar terhadap pertumbuhan anakan kayu kuku (Pericopsis mooniana Thw.) di persemaian [Growth and survival of transplants of bare-rooted Pericopsis mooniana Thw. wildlings as affected by stem height and hormonal treatment of the roots]. Buletin Penelitian Hutan No 515: 19-28.
• Whitmore, T.C., 1972. Leguminosae, Pericopsis. In: Whitmore, T.C. (Editor): Tree flora of Malaya. Vol. 1. Longman Malaysia SDN Berhad, Kuala Lumpur. p. 302.

Other selected sources

168, 182, 231, 251, 266, 318, 333, 365, 371, 550, 726, 772.

Authors

• K. Sidiyasa (general part),
• I. Soerianegara (general part),
• A. Martawijaya (properties),
• S. Sudo (wood anatomy)