Vernonia (PROSEA Timbers)

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Plant Resources of South-East Asia
Introduction

List of species

Vernonia Schreber

Protologue: Gen. pl. 2: 541 (1791).

Family: Compositae

Chromosome number: x= 9; V. arborea: 2n= c. 30

Vernacular names

Indonesia: merambung (general)
Philippines: malasambong (general).

Origin and geographic distribution

Vernonia is a very large genus of about 1000 species occurring in tropical, subtropical and temperate regions of America, Africa and Asia with its main centre of diversity in the Neotropics. In the Malesian region about 35 species occur, most of which are herbs, shrubs or climbers; only 2 species are trees.

Uses

The wood of Vernonia is used for wood-based panels, temporary construction, household appliances and matches. It may be used for carvings and wooden clogs.

V. arborea may be useful in reforestation and erosion control. A decoction of the bark together with other ingredients or an infusion of the root, may be given against fever. In southern Sumatra the bark was chewed at the first signs of sprue.

Production and international trade

Vernonia wood is used only locally, but the timber is regarded as commercial in Indonesia, probably because of the fairly large local supplies.

Properties

Vernonia yields a lightweight hardwood with a density of 240-620 kg/m³ at 15% moisture content. Heartwood pale brown to pale grey, not clearly differentiated from the sapwood; grain straight or slightly interlocked; texture rather coarse but even; wood with conspicuous silver grain. Growth rings indistinct, occasionally visible; vessels medium-sized, solitary and in radial multiples of 2-3, sometimes in clusters, with occasional white deposits; parenchyma rather sparse, paratracheal vasicentric, sometimes tending to aliform, especially near growth ring boundaries; rays medium-sized, visible to the naked eye and conspicuous on tangential surface; ripple marks absent.

The wood seasons well. It is soft, weak to moderately strong and can be worked easily. It is non-durable and very susceptible to dry-wood termites and fungi.

The energy value of oven-dry sapwood is about 19 750 kJ/kg.

See also the tables on microscopic wood anatomy and wood properties.

Botany

Evergreen herbs, shrubs, climbers or rarely small to medium-sized trees up to 30(-40) m tall; bole up to 60(-100) cm in diameter, with short buttresses; bark surface becoming closely narrowly fissured or scaly, dark grey to brown, inner bark fibrous, pale brown to orange-brown turning darker or purplish upon exposure.
Leaves arranged spirally, simple, entire, glandular below; exstipulate.
Inflorescence terminal or in the upper leaf axils, consisting of widely branched panicles of heads.
Head with 5-6 white flowers which are much longer than the involucre; involucre campanulate; receptacle naked; corolla tubular with a campanulate to funnel-shaped limb; anthers with sagittate base.
Fruit a ribbed, 3-angled achene which is flattened on two sides and rounded on the third; pappus hairs usually 2- or rarely 1-seriate, scabrous.

In general, flowering is during the dry season. In Peninsular Malaysia trees flower from June to August and sometimes also in January and February.

V. arborea is very polymorphic and formerly many varieties were distinguished. The occurrence of an array of intermediate forms, however, makes their separation unrealistic. The tree habit is very rare within the Compositae, and V. arborea possibly represents a highly derived form or a primitive trait within the genus Vernonia.

Ecology

V. arborea is locally common in secondary forest, along roadsides and also in fields with alang-alang (Imperata cylindrica (L.) Raeuschel). It is found from lowland to lower montane habitats up to 2200(-3000) m altitude. In the Philippines it occurs in dipterocarp forest. In mountains in East Java V. arborea is conspicuous in the succession to mixed oak-laurel forest. V. vidalii is found scattered, chiefly in secondary forest and old clearings, up to 1300 m altitude.

Silviculture

V. arborea shows a high seed sterility (nearly 100%) but is, paradoxically, a common pioneer of forest edges. Germination starts after 10-14 days after sowing and young seedlings need shelter. They can be pricked out when 10 cm tall. Growth is reportedly fairly rapid. Plants are capable of resprouting after dying back due to drought.

Genetic resources and breeding

Being common in secondary vegetation, there seems to be little risk of genetic erosion of V. arborea.

Prospects

As the wood quality is very poor, increased use of V. arborea for sawn timber is unlikely. Increased use for the manufacture of wood-based panels is a possibility.

Literature

[70]Backer, C.A. & Bakhuizen van den Brink Jr., R.C., 1963-1968. Flora of Java. 3 volumes. Wolters-Noordhoff, Groningen.
[101]Beekman, H., 1920. 78 Preanger houtsoorten. Beschrijving, afbeelding en determinatietabel [78 Priangan wood species. Description, pictures and identification key]. Mededeelingen No 5. Proefstation voor het Boschwezen, Buitenzorg. 186 pp.
[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.
[198]Cockburn, P.F., 1976-1980. Trees of Sabah. 2 volumes. Sabah Forest Records No 10. Forest Department Sabah, Sandakan.
[209]Corner, E.J.H., 1988. Wayside trees of Malaya. 3rd edition. 2 volumes. The Malayan Nature Society, Kuala Lumpur. 774 pp.
[239]de Voogd, C.N.A., 1938. Eenige aanteekeningen betreffende de boschculturen op Bali gedurende de periode 1933-1936 [Some notes on the forest plantations in Bali in the period 1933-1936]. Tectona 31: 232-247.
[260]den Berger, L.G., 1926. Houtsoorten der cultuurgebieden van Java en Sumatra's oostkust [Tree species of the cultivated areas of Java and the east coast of Sumatra]. Mededeelingen No 13. Proefstation voor het Boschwezen, Buitenzorg. 186 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.).
[464]Ilic, J., 1990. The CSIRO macro key for hardwood identification. CSIRO, Highett. 125 pp.
[526]Kartasujana, I. & Martawijaya, A., 1979. Kayu perdagangan Indonesia - sifat dan kegunaannya [Commercial woods of Indonesia - their properties and uses]. Lembaga Penelitian Hasil Hutan, Bogor. 28 pp.
[597]Koster, J.T., 1935. The Compositae of the Malay Archipelago. I. Vernonieae and Eupatorieae. Blumea 1: 351-536.
[827]Ng, F.S.P., 1983. Ecological principles of tropical lowland rain forest conservation. In: Sutton, S.L., Whitmore, T.C. & Chadwick, A.C. (Editors): Tropical rain forest: ecology and management. Special Publication number 2 of the British Ecological Society. Blackwell Scientific Publications, Oxford, London, Edinburgh, Boston, Melbourne. pp. 359-375.
[933]Research Institute of Wood Industry, 1988. Identification, properties and uses of some Southeast Asian woods. Chinese Academy of Forestry, Wan Shou Shan, Beijing & International Tropical Timber Organization, Yokohama. 201 pp.
[934]Reyes, L.J., 1938. Philippine woods. Technical Bulletin No 7. Commonwealth of the Philippines, Department of Agriculture and Commerce. Bureau of Printing, Manila. 536 pp. + 88 plates.
[947]Rierink, A., 1938. Over de caloriemetrische verbrandingswaarde van een zestigtal Ned. Indische houtsoorten [The calorific value of about 60 woods from the Dutch East Indies]. Tectona 31: 400-418.
[974]Salvosa, F.M., 1963. Lexicon of Philippine trees. Bulletin No 1. Forest Products Research Institute, College, Laguna. 136 pp.
[1038]Smitinand, T., 1980. Thai plant names. Royal Forest Department, Bangkok. 379 pp.
[1218]Whitmore, T.C., 1984. Tropical rainforest of the Far East. 2nd edition. Clarendon Press, Oxford. xvi + 352 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.
[1242]Wong, T.M., 1982. A dictionary of Malaysian timbers. Malayan Forest Records No 30. Forest Research Institute Malaysia, Kepong. 259 pp.

Selection of species

Authors

B. Ibnu Utomo