Cynometra (PROSEA)

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Plant Resources of South-East Asia
Introduction
List of species


Cynometra L.

Protologue: Sp. pl.: 382 (1753); Gen. pl. (Ed. 5): 179 (1754).
Family: Leguminosae
Chromosome number: 2n= unknown

Trade groups

Kekatong: heavy hardwood, e.g. Cynometra malaccensis Knaap-v. Meeuwen, C. ramiflora L.

Vernacular names

Kekatong

  • Indonesia: kateng, kepel (Java)
  • Malaysia: belangan (Peninsular), katong, katong-katong (Sabah, Sarawak)
  • Philippines: oringen, balitbitan (Tagalog)
  • Cambodia: chôm'prinh
  • Thailand: mangkhak (Phuket), katong (Narathiwat).

Origin and geographic distribution

Cynometra is pantropical and consists of about 150 species, most of which occur in South America. Within Malesia some 20 species are currently recognized, but several more might be present in New Guinea.

Uses

The wood of kekatong, being not durable or only moderately so, is suitable for interior construction, door and window frames, heavy-duty flooring and interior trim. When treated with preservative it is also suitable for heavy outdoor construction, poles, posts, beams, railway sleepers, fenders, and for boat and ship building. Kekatong is also suitable for tool handles, toys and novelties. The hardness of the wood makes it generally unsuitable for plywood and veneer. Some species have attractive corewood, especially several species from India, Indo-China and Peninsular Malaysia, and are used for decorative panelling, parquet flooring and turnery. The wood yields good-quality charcoal.

The fruits of Cynometra cauliflora L. (namnam) are edible and used for various purposes such as compote, sambal and in salads. The same species is sometimes planted as an ornamental.

Production and international trade

Kekatong is not an important export timber, and only very small amounts are exported. No figures are available, except for the export of round logs from Sabah in 1987, which amounted to only 200 m3 with a value of US$ 16 000 (price: US$ 80/m3).

Properties

Kekatong is a heavy hardwood. The heartwood is golden-brown, deep pinkish-brown to red when freshly cut, darkening to dark red on exposure, corewood often brown-black or chocolate brown. The heartwood is not sharply demarcated from the pale pinkish-brown sapwood. Planed surfaces are generally not lustrous; the wood is attractively streaked on radial surfaces and mottled on tangential surfaces. The density is (720-)850-1065(-1155) kg/m3 at 15% moisture content. The grain is straight to slightly or deeply interlocked, occasionally spiral, texture moderately fine, often uneven.

At 19% moisture content the modulus of rupture is 135-163 N/mm2, modulus of elasticity 18 400-18 900 N/mm2, compression parallel to grain 67-87 N/mm2, compression perpendicular to grain 11.5-13.5 N/mm2, shear 15.5-20 N/mm2, cleavage c. 61 N/mm radial and 74 N/mm tangential, Janka side hardness 12 370-13 820 N and Janka end hardness c. 12 600 N.

The rates of shrinkage from green to air dry (19% moisture content) are 1.6% radial and 2.7% tangential. Kekatong air dries moderately fast for a heavy hardwood. Boards of 40 mm thick take about 5 months to air dry, 15 mm thick boards take about 3 months. Cupping, bowing, twisting and springing do not usually occur during drying, but end checking and splitting may cause problems. Kekatong can be kiln dried easily; 25 mm thick boards take approximately 8 days to dry. Kiln schedule B (Malaysia) is recommended. It is advised to use end coating.

In green condition, the wood is easy to resaw but difficult to cross cut; in air dry condition it is difficult to saw with ordinary saws but chromium-plated teeth give good results. The wood planes to a smooth finish; it polishes well, but pre-boring is necessary for nailing. It peels satisfactorily, but the often irregular shape of the logs and their high density make the timber unsuitable for plywood. It is also considered too dense for chipboard.

Kekatong is moderately durable in contact with the ground under tropical conditions. Graveyard tests in Malaysia show an average service life of 4.2 years. Wood of C. inaequifolia and C. ramiflora is said to be not durable. It is resistant to termites, but the sapwood is often attacked by powder-post beetles, and the wood of C. ramiflora by longhorn beetles. Kekatong is not resistant to marine borers. It is durable for both interior and exterior work under temperate conditions. The wood is usually very difficult to treat with preservatives, but there are also reports of kekatong wood which absorbs preservatives fairly well.

Description

  • Shrubs or small to fairly large evergreen trees of up to 40 m tall; bole sometimes of poor shape, up to 80 cm in diameter, with or without buttresses; bark surface smooth, lenticellate, grey to brown, sometimes with an exudate, sapwood not well-defined; buds small, with numerous brown scales in two rows; new leaves developing in bright pink tassels.
  • Leaves alternate, paripinnate, with 1-3(-6) pairs of opposite leaflets, young leaves often in white, pendulous tassels; petiole short, with stipules falling immediately after the unfolding of the bud, leaving no scar; leaflets sessile or shortly petiolate, asymmetrical, entire, leathery, often abruptly tipped, base very unequal, cuneate on the distal side, variously rounded on the basal side, usually glabrous.
  • Inflorescence usually a dense, sessile, axillary raceme with 1(-2) racemes per axil, exceptionally cauliflorous and then 3-5 racemes together; bracts scale-like, bracteoles caducous after anthesis.
  • Flowers bisexual, more or less irregular, small; receptacle short, campanulate, circumscissile under the ripening fruit; calyx with 4(-5) free, imbricate sepals reflexed at anthesis; corolla with 5, narrow, free, glabrous petals, the lateral petals covering the standard in the bud; disk absent; stamens (8-)10(-15), free, of equal length or alternately shorter and longer, sometimes 1 stamen sterile, anthers medi-dorsifix, lengthwise dehiscent, introrse, c. 1 mm long, the connective very often cleft below the insertion of the filament, mostly apiculate at the apex; ovary superior, 1-celled, with 1(-2) ovules, stipe central or excentric, rarely merged with the receptacle.
  • Fruit a fleshy to woody pod, 1(-2)-seeded, indehiscent, oblong, flat to globose, smooth or rugose, sometimes warty, often brown with a thickened stipe.
  • Seed circular, compressed, with a large embryo and little or no endosperm.
  • Seedling with epigeal or hypogeal germination; the cotyledons equal, being massive foodstoring organs.

Wood anatomy

Macroscopic characters

  • Sapwood up to 90 mm wide, pale pinkish-brown, gradual transition to darker coloured heartwood but clearly demarcated from deep pinkish grey-brown to dark brown inner heartwood.
  • Grain straight to slightly or deeply interlocked, occasionally spiral.
  • Texture medium to fine, uneven. Figure with attractive streaks on quartersawn faces, with slight lustre or not lustrous.
  • Growth rings not evident although zones of fibres without parenchyma and vessels may give an impression of growth rings.
  • Vessels medium to small, not readily discernible to the naked eye, with white or pinkish chalk-like deposits.
  • Parenchyma abundant, paratracheal, wide bands visible to the naked eye often forming attractive zig-zag patterns on backsawn surfaces.
  • Rays fine, individual rays barely discernible to the naked eye.
  • Ripple marks absent.

Microscopic characters

  • Growth rings inconspicuous.
  • Vessels diffuse, 2-5(-10)/mm2, solitary and in radial multiples of 2-3(-4), clusters rare, mostly circular to oval, average tangential diameter 120-140(-220)μm; perforations simple; intervessel pits loosely alternate, rounded, 3-4(-5)μm, vestured; vessel-ray and vessel-parenchyma pits similar but half-bordered; helical thickenings absent; tyloses absent.
  • Fibres 1.5-2.5 mm long, non-septate, moderately thick- to thick-walled, with simple pits mainly in radial walls.
  • Parenchyma abundant, aliform to confluent, forming more or less continuous or wavy, regularly spaced bands, 6-7 cells wide; occasionally in marginal bands 1-2 cells wide; in 2-4, mostly 4-celled strands.
  • Rays 8-10/mm, narrow, (1-)2-3(-4)-seriate, c. 0.6 mm high, highest rays up to 1.5 mm, weakly heterocellular (Kribs type heterogeneous III and II).
  • Prismatic crystals in chambered vertical parenchyma cells and mainly in procumbent ray cells, occasionally in chambered upright cells; extraneous brownish coloured materials abundant in parenchyma and ray cells.

Superficially Dialium and Koompassia resemble Cynometra but differ by having ripple marks (storied structure). Anatomically, Maniltoa wood is almost identical to Cynometra but differs by being paler in colour, usually more dense, having chambered crystals confined to upright ray cells, somewhat more heterocellular rays, and having some radial multiples with up to 6 vessels.

Species studied: C. cauliflora, C. inaequifolia, C. malaccensis, C. ramiflora.

Growth and development

Kekatong grows in distinct flushes. The trees are slow growers; the maximum diameter for trees of C. malaccensis is reported to be only 37.5 cm at an age of 40 years.

Other botanical information

The genus Cynometra belongs to the tribe Cynometreae together with five other closely related genera. It differs from the other genera by floral characters only. It is doubtful whether Cynometra is truly distinct from Maniltoa, because Maniltoa polyandra (Roxb.) Harms occupies an intermediate position. The delimitation of Cynometra from the other genera within the tribe is less controversial.

Ecology

Cynometra species occur in lowland forest and some are associated with waterlogged conditions or grow along rivers. Several species characteristically occur in mangrove forest. Kekatong generally occurs in primary forest but sometimes also in secondary forest, usually up to 900 m, though in New Guinea it is found up to 1300 m.

Silviculture and management

Kekatong is never planted; trees are felled in natural forest, and to date there has been no replanting or enrichment planting.

Harvesting

The logs cannot be transported by river because they sink in water; they must be transported over land.

Genetic resources

Some species are considered locally endangered and should be protected there, e.g. C. ramiflora in the Philippines.

Prospects

The prospects for exploitation of kekatong are limited because the wood has restricted utility. The trees grow slowly and the boles are often of poor form and small dimension.

Literature

  • Browne, F.G., 1955. Forest trees of Sarawak and Brunei and their products. Government Printing Office, Kuching. pp. 223-224.
  • Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department Sabah, Sandakan. pp. 347-350.
  • Cockburn, P.F., 1976. Trees of Sabah. Vol. 1. Sabah Forest Records No 10. Forest Department Sabah, Kuching. pp. 160-164.
  • de Guzman, E.D., Umali, R.M. & Sotalbo, E.D., 1986. Guide to Philippine flora and fauna. Vol. 3: Dipterocarps, non-dipterocarps. Natural Resources Management Center and University of the Philippines, Quezon City. pp. 200-201.
  • Desch, H.E., 1954. Manual of Malayan timbers. Vol. 1. Malayan Forest Records No 15. Malaya Publishing House Ltd., Singapore. pp. 268-270.
  • 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. p. 106.
  • Knaap-van Meeuwen, M.S., 1970. A revision of 4 genera of the tribe Leguminosae-Caesalpinioideae-Cynometreae in Indo-Malesia and the Pacific. Blumea 18: 1-52.
  • Larsen, K., Larsen, S.S. & Vidal, J.E., 1984. Leguminosae - Caesalpinioideae. In: Smitinand, T. & Larsen, K. (Editors): Flora of Thailand. Vol. 4(1). The Forest Herbarium, Royal Forest Department, Bangkok. pp. 1-129a.
  • Mohd. Shukari, M., 1983. Malaysian timbers - kekatong. Malaysian Forest Service Trade Leaflet No 79. Malaysian Timber Industry Board, Kuala Lumpur. 7 pp.
  • Whitmore, T.C., 1983. Leguminosae, Cynometra. In: Whitmore, T.C. (Editor): Tree flora of Malaya. 2nd edition. Vol. 1. Malaysian Forest Records No 26. Longman Malaysia SDN Berhad, Kuala Lumpur. pp. 253-255.

Selection of species

Authors

  • I. Soerianegara (general part),
  • A. Martawijaya (properties),
  • J. Ilic (wood anatomy),
  • M.H.A. Hoffman (selection of species)