5655

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

Ixora L.

Sp. pl. 1: 110 (1753); Gen. pl., ed. 5: 48 (1754).

RUBIACEAE

x = 11; for most species: 2n = 22

Indonesia: areng-arengan (Javanese), ki soka (Sundanese). Malaysia: jarum-jarum, pechah periuk, todong periok (Peninsular). Burma (Myanmar): pan, ponna. Cambodia: chann tanea, tè prey. Thailand: kheme (general).

Ixora comprises about 400 species and is distributed throughout the tropics. The Indo-Malesian region is richest in species. In Malesia about 160 species occur; the highest number of species is found in Borneo, about 65, most of them endemic. Only a few species reach timber size.

The wood of Ixora is occasionally used, often for implements and comparatively small objects such as walking sticks, sometimes also for beams in house building.
Some Ixora species are well-known as an ornamental (e.g. I. chinensis Lamk, I. coccinea L., I. javanica (Blume) DC.), commonly planted in gardens, parks and roadsides. Several species are used in traditional medicine, e.g. as an astringent and to treat dysentery and tuberculosis. Some species (e.g. I. coccinea) have shown anti-tumour and anti-mutagenic activity. The fruits of I. philippinensis Merr. are edible.

Utilization of the wood of Ixora is limited and on a local scale only.

Ixora yields a heavy hardwood with a density of 940-1010 kg/m³ at 15% moisture content. Heartwood pale brown with a pinkish tinge, not clearly differentiated from the sapwood; grain straight; texture very fine and even. Growth rings visible to the naked eye, defined by a layer of parenchyma; vessels moderately small, almost exclusively solitary with very occasional radial pairs, open; parenchyma moderately abundant, apotracheal diffuse and diffuse-in-aggregates, or in narrow or marginal bands, very occasionally scanty paratracheal; rays extremely fine or very fine; ripple marks absent.
The wood is very strong and durable. As the vessels are very small, the sapwood is probably non-susceptible to Lyctus.
See also the table on microscopic wood anatomy.

Generally evergreen (in Malesia) shrubs or small to sometimes medium-sized trees up to 25 m tall; bark surface smooth, lenticellate, fissured or scaly, greyish-brown; twigs terete, often with series of rather close, leafless nodes especially at branching points. Leaves opposite or sometimes in whorls of 3, simple, entire; stipules connate at base, distinctly cuspidate or with a long, stiff, needle-like extension at the tip. Flowers in a terminal corymb or corymbose panicle, 4-merous, often 3 together; calyx often divided to the base; corolla with a cylindrical tube, lobes contorted in bud, often white but sometimes pink, yellow or red; stamens inserted at corolla throat, with short filaments, anthers sagittate and reflexed out of the open flower; disk annular; ovary inferior, 2(-3)-locular with 1 ovule per cell, style slightly exserted from the corolla tube, with 2-lobed stigma. Fruit a globose to 2-lobed drupe, ripening red to black, 1-2-seeded. Seedling with epigeal germination; cotyledons leafy, green.
Flowering is seasonal but cultivated varieties bloom throughout the year. The flowers are mainly pollinated by moths and butterflies probing for the nectar at the corolla base, but honey-suckers may also visit the flowers, particularly the reddish ones. The fruits are probably dispersed by fruit-eating birds.
Pavetta closely resembles Ixora, but can be distinguished by its long-exserted style with coherent stigmas.

Ixora species are usually confined to lowland and lower montane forest up to 1700 m altitude. Some species are also found in swampy locations in the vicinity of rivers or occasionally in rice fields (e.g. I. grandifolia).

Ixora may be propagated by seed, although ornamental species are usually propagated by cuttings. Both seed and sown fruits of I. lobbii Loudon had about 25% germination in 1-3 months.

Ixora trees are not much sought after for their wood, since they are small in size. Therefore, logging for timber does not seem to affect the size of its population, except when an area is clear cut.

Ixora timber is seldom used, mainly because of its small dimensions. Its utilization is unlikely to increase.

[70]Backer, C.A. & Bakhuizen van den Brink Jr., R.C., 1963-1968. Flora of Java. 3 volumes. Wolters-Noordhoff, Groningen.
[137]Bremekamp, C.E.B., 1937. The Malaysian species of the genus Ixora (Rub.). Contributions à l'étude de la flore des Indes Néerlandaises XXXIV. Bulletin du Jardin Botanique, Buitenzorg, Série III, 14: 197-367.
[163]Burkill, I.H., 1966. A dictionary of the economic products of the Malay Peninsula. 2nd edition. Ministry of Agriculture and Co-operatives, Kuala Lumpur. Vol. 1 (A-H) pp. 1-1240. Vol. 2 (I-Z) pp. 1241-2444.
[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.
[436]Heyne, K., 1927. De nuttige planten van Nederlands-Indië [The useful plants of the Dutch East Indies]. 2nd edition, 3 volumes. Departement van Landbouw, Nijverheid en Handel in Nederlandsch-Indië. 1953 pp. (3rd edition, 1950. van Hoeve, 's-Gravenhage/Bandung. 1660 pp.).
[790]Metcalfe, C.R. & Chalk, L., 1957. Anatomy of the dicotyledons. 2 volumes. Corrected edition. Clarendon Press, Oxford. 1506 pp.
[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.
[861]Oey Djoen Seng, 1951. De soortelijke gewichten van Indonesische houtsoorten en hun betekenis voor de praktijk [Specific gravity of Indonesian woods and its significance for practical use]. Rapport No 46. Bosbouwproefstation, Bogor. 183 pp.
[1164]Verheij, E.W.M. & Coronel, R.E. (Editors), 1991. Plant resources of South-East Asia No 2. Edible fruits and nuts. Pudoc, Wageningen. 446 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.

B. Ibnu Utomo W.

Ixora amplexifolia
Ixora concinna
Ixora glomeruliflora
Ixora grandifolia
Ixora simalurensis
Ixora trichandra

Ibnu Utomo, B.W., 1998. Ixora L.. 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:
Ixora amplexifolia
Ixora concinna
Ixora glomeruliflora
Ixora grandifolia
Ixora simalurensis
Ixora trichandra