Vernicia montana (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Vegetable oil
Medicinal
Timber
Fuel
Ornamental
Forage / feed
Auxiliary plant
Fibre

Vernicia montana Lour.

Protologue: Fl. cochinch. 2: 586 (1790).

Family: Euphorbiaceae

Chromosome number: 2n = 22

Synonyms

• Aleurites montana (Lour.) E.H.Wilson (1913).

Vernacular names

• Wood-oil tree, mu-tree, Cantonese wood-oil tree, abrasin-oil tree (En).
• Abrasin, arbre à huile de bois (Fr).
• Falso castanheiro (Po).

Origin and geographic distribution

Vernicia montana is native to Myanmar, Thailand, Indo-China and southern China. It has been introduced into many tropical and subtropical areas. In tropical Africa it has been introduced and has sometimes naturalized, e.g. in Kenya, Tanzania, Malawi, Zambia, Zimbabwe, Mozambique and Madagascar. On a commercial scale it has been grown in Malawi and Madagascar.

Uses

The seeds of Vernicia montana yield a quick-drying oil called ‘abrasin oil’ or ‘Chinese wood oil’. Because of its similarity to ‘tung oil’ from Vernicia fordii (Hemsl.) Airy Shaw, the oils are often treated together as tung oil. In China the oil is used traditionally in the manufacture of paints and Chinese black ink, for waterproofing cloth and paper, caulking and painting ships and as a lamp oil. It was also formerly used for insulating electric wires. Currently, its main use is in the production of paints and inks, while low-quality oil is processed into soap or linoleum. Teak oil which is sold for maintaining fine furniture is usually refined tung oil. Developments in environmental and health regulations have led to an increasing use of tung oil to line containers for food, beverages and medicines with an insulating coating. The press cake, after extraction of the oil, is a good fertilizer, but it is poisonous and cannot be used as animal feed.

In medicine, tung oil is used to treat parasitic and other skin diseases and is a strong purgative. It is a component of nearly all Chinese plasters.

The wood is only suitable for simple construction, corestock for plywood, paper pulp and firewood. Vernicia montana is sometimes planted as an ornamental and shade tree.

Production and international trade

The oils from Vernicia montana and Vernicia fordii are traded together as tung oil. Annual world production of Vernicia fruits in the late 1990s was about 500,000 t from 170,000 ha, yielding 90,000 t oil. China produced 85% of the world production of which about 25% was exported. Since then the share of China has further increased. In 2004 it exported 19,000 t of oil, Paraguay 3600 t and Argentina 1300 t. Tung oil production in Malawi started in the 1930s. Exports grew to 1800 t in 1965, but then gradually declined to less than 400 t in the period 1975–1985 and to almost nil in the 1990s. Exports from Madagascar reached a peak of 1200 t in the late 1960s, but then also collapsed rapidly. Prices have fluctuated from over US$ 3000 per t at the end of 1993 to US$ 1200 two years later, they now average about US$ 1350.

Properties

The fruit of Vernicia montana contains per 100 g 14–20 g of a drying oil. The oil is contained in the seed which makes up about 33% of the fruit. The main fatty acid of the oil is α-eleostearic acid or cis-trans-trans 9,11,13-octadecenoic acid, a trienoic fatty acid, isomeric with linolenic acid. In eleostearic acid, the 3 double bonds are conjugated making them highly reactive. Under the influence of light or catalysts such as sulphur and iodine, α -eleostearic acid converts to β-eleostearic acid, which is even more reactive and spontaneously polymerizes into a solid mass. The eleostearic acid makes tung oil a virulent purgative when taken internally. The fatty acid composition of the oil is: α-eleostearic acid 75–80%, palmitic acid 4%, stearic acid about 1% and oleic acid 15%. In the triglycerides, most eleostearic acid is bound in the 1 and 3 positions.

Other components of the fruits of both species include tannins, phytosterols and a poisonous saponin. Animals, including cattle, horses and chicken that have eaten the leaves or seed cake show haemorrhagic diarrhoea accompanied by anorexia. In severe cases, they become emaciated and may die in 1–3 weeks. The fruits of Vernicia are attractive in appearance and taste, but ingestion by humans of even a single seed causes severe abdominal cramps, vomiting, diarrhoea and general exhaustion after 3–5 hours.

The wood is white, soft and perishable.

Description

• Dioecious or sometimes monoecious, deciduous or evergreen shrub or small tree up to 15 m tall; young shoots, leaves and young fruits reddish brown hairy.
• Leaves alternate, simple; stipules lanceolate, 2–4 mm long, early caducous, leaving fairly prominent scars; petiole up to 25 cm long, grooved, with 2 stalked glands at junction with blade; blade ovate to broadly ovate or 3–5-palmately lobed, up to 20 cm × 18 cm, acuminate at apex, margins entire.
• Inflorescence a terminal, usually unisexual panicle composed of cymes; male inflorescence 15 cm × 15–20 cm, female inflorescence resembling the male one but often smaller.
• Flowers unisexual, showy; calyx covering bud and rupturing into 2(–3), often unequal lobes; petals 5(–6), free, oblanceolate to spatulate, 1.5–2.5 cm long, white, clawed; disk of 5–6(–7) erect glands up to 4 mm long; male flower with (7–)8–12(–14) stamens in 2 whorls, united into a c. 2 cm long column; female flowers with superior ovary, densely hairy, 3(–5)-celled, styles c. 8 mm long, united at base, 2-lobed.
• Fruit an ovoid to globose capsule c. 3.5 cm × 4 cm, apex pointed, with 3(–5) distinct longitudinal ridges and few transverse ribs, tardily dehiscent, glabrescent.
• Seeds obovoid to globose, 2–2.5 cm × 2–2.5 cm, pointed, brown with longitudinal beige variegations, smooth, hilum large. Seedling with epigeal germination; cotyledons broad, flat.

Other botanical information

The genera Aleurites, Reutealis and Vernicia are closely related and have long been combined in Aleurites. Vernicia comprises 3 species originating from Asia.

Vernicia cordata

Vernicia cordata (Thunb.) Airy Shaw from Japan has been introduced into Senegal. It yields ‘Japanese wood oil’.

Vernicia fordii

Vernicia fordii originates from central and western China and has been cultivated for its oil in many subtropical areas. It has been tested at higher altitudes in the tropics (e.g. Malawi and Madagascar), but there Vernicia montana performs better.

Growth and development

Two branching patterns occur in Vernicia montana, recognized in Malawi as types A and B. Similar types are also recognized in Indonesia as the Indo-China type and the China type. Type A is a fast-growing tree with a tall, straight trunk forming tiers of 5 spreading branches at regular intervals. Secondary branches form at relatively long intervals. Trees take 3–5 years to come into bearing. Type B is more shrub-like. When the main stem has produced 1 or 2 tiers of branches, it looses its dominance. Secondary branches are formed at short intervals. The trees come into bearing after 3 years. From the B type, several high-yielding vigorously growing clones have been selected.

Flowers open in the morning. In female flowers, the stigma is already receptive 1 day earlier, while in male flowers pollen is released at anthesis. Pollen is sticky and pollination is performed by insects such as butterflies and bees. Some honey-bee species, however, are common visitors of male flowers, but are rarely seen on female flowers and contribute little to pollination. The number of fruits set is generally high, but about 80% may abort during development.

Where Vernicia fordii and Vernicia montana grow together and flower simultaneously, hybridization is common, but the hybrids have no agronomic advantages.

Ecology

Vernicia montana is planted in areas with annual rainfall of 850–2000 mm and average annual temperatures of 15–27°C. In tropical areas it is planted at altitudes of 800–2000 m. Its requirement of low temperatures for flower initiation is less than that of Vernicia fordii and it is sensitive to frost. Vernicia montana is often grown on slopes, but grows well on flat land provided it is well-drained. It prefers slightly acid soils and is susceptible to accumulations of ash; it occurs on soils of pH 5.5–8.0. Adequate soil fertility is needed for good production.

Propagation and planting

Commercial plantings of Vernicia consist mostly of selected clones budded onto seedling rootstock. Fresh seed germinates quickly, but germination of older seed may take 2–3 months unless it is scarified. The weight of 100 seeds is about 325 g. When de loop of the hypocotyl becomes visible above the ground, seedlings are transferred from the germination bed to the nursery. Seedlings are transplanted into the field when they are 1 year old. In Malawi budding is done in the nursery. The simple shield method of budding at a height of 5–7.5 cm above the ground is commonly applied. In China planting density is about 600 trees/ha; in Malawi early plantations were established at about 7.5 m × 7.5 m, but in later plantings the plant density was increased. Plantations with a close planting system reach maximum production at an earlier age but the maximum yields are the same as those from trees that are more widely spaced. Hedgerow systems have been developed.

Management

Young trees of Vernicia montana are often intercropped with food crops such as maize, groundnut or soya bean in China. In Malawi intercropping with annuals or planting of cover crops was common. Prolonged intercropping with annual crops may cause damage to the shallow root system of Vernicia montana, but in China even mature trees are sometimes intercropped with winter crops. Regular weeding around the plants is needed also for ease of harvesting. In hedgerow systems, pruning and training are recommended to obtain a frame of a few main branches and open crown. Little is known about the fertilizer requirements. In Malawi application of 50 kg N/ha as sulphate of ammonium gave yield increases of 400–1000 kg dry seed/ha. Application of the press cake as fertilizer has also given good results.

Seedling trees that do not produce well can be cut back and scions from high-yielding material can be grafted into the stump.

Diseases and pests

In China anthracnose caused by Glomerella cingulata (synonym: Colletotrichum gloeosporioides) sometimes causes severe losses. Other important diseases include root rot caused by Fusarium solani and brown leaf spot caused by Mycosphaerella aleuritides. In Malawi the main diseases of Vernicia montana are die-back caused by Botryosphaeria ribis and root rot caused by Armillaria mellea. Selection of adapted plant material is the best way to avoid these diseases.

Insect pests are rarely a problem as the leaves and seeds are toxic to most animals. Vernicia montana is resistant to the thrips Selenothrips rubrocinctus, which causes damage in Vernicia fordii in China.

Harvesting

Harvesting by manual collection of fallen fruits is most common, but in China green fruits are also picked from the trees. Careful selection of clones can extend the harvesting season. During the rainy season, fruits should be collected every 10 days, and during the dry season about once a month.

Yield

Average yields of Aleurites montana are 3.5 t/ha in China and 1.8 t/ha in Malawi. In Malawi annual yields of air-dry seed of the best clonal material gradually increase from 280 kg/ha in 3–6-year-old plantations to 2200 kg/ha in 11–14-year-old plantations and 3000 kg/ha in 20-years-old plantations; yields of plantations of unselected seedling material are about half these amounts.

Handling after harvest

In China the fruit is traditionally collected when still green, placed in heaps and covered with straw or grass. The fruit pulp is allowed to rot until the seeds can be easily removed. The seeds are then crushed in a mill and roasted for a short time in shallow iron pans. The crushed mass is then thoroughly steamed and subsequently the fluid is pressed out of the cake yielding commercial wood oil. In modern processing, hulling of fruits is done by hand or mechanically. The seeds are then dried and shelled mechanically, after which the kernels are ground with some shell added to facilitate oil extraction. Cold-expression is done in screw presses yielding a clear, light-coloured oil. The cake may subsequently be warm-pressed or solvent-extracted to increase the yield, but the product is of lower quality.

Genetic resources

Vernicia montana is very variable and there are only few true breeding lines. No germplasm collections are known to exist. In the United States, the National Plant Germplasm System no longer maintains its former collection of Vernicia.

Breeding

Selection work has been done in Malawi, but was discontinued. Breeding and selection programmes have been implemented in China and Taiwan.

Prospects

In spite of the excellent quality of tung oil as a wood oil or a raw material for paint production, the decline of the tung oil production in all countries except China indicates that prospects to revive former plantations or establish new ones are bleak.

Major references

• Aguilar, N.O. & Ong, H.C., 2001. Vernicia Lour. In: van der Vossen, H.A.M. & Umali, B.E. (Editors). Plant Resources of South-East Asia No 14. Vegetable oils and fats. Backhuys Publishers, Leiden, Netherlands. pp. 142–146.

• Hill, J., 1965. Aleurites montana: the relative value of some Malawi selections. Tropical Agriculture 42: 311–321.

• Hill, J., 1966. Close planting in montana tung. Tropical Agriculture 42: 11–18.

• Hill, J. & Spurling, A.T., 1966. A note on the classification of montana tung (Aleurites montana). Tropical Agriculture 42: 19–24.

• Phiri, I.M.G., 1985. Effects of nitrogen and hedge row systems on the yield and quality of tung nuts. Acta Horticulturae 158: 265–271.

• Radcliffe-Smith, A., 1987. Euphorbiaceae (part 1). In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 407 pp.

• Radcliffe-Smith, A., 1996. Euphorbiaceae, subfamilies Phyllantoideae, Oldfieldioideae, Acalyphoideae, Crotonoideae and Euphorbioideae, tribe Hippomaneae. In: Pope, G.V. (Editor). Flora Zambesiaca. Volume 9, part 4. Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 1–337.

• Stuppy, W., van Welzen, P.C., Klinratana, P. & Posa, M.C.T., 1999. Revision of the genera Aleurites, Reutealis and Vernicia (Euphorbiaceae). Blumea 44: 73–98.

• Webster, C.C., Wiehe, P.O. & Smee, C., 1950. The cultivation of the tung-oil tree (Aleurites montana) in Nyasaland (A practical guide for growers). The Government Printer, Zomba, Malawi. 48 pp.

Other references

• Airy Shaw, H.K., 1967. Generic segregation in the affinity of Aleurites J.R. & G. Forster. Kew Bulletin 26: 393–395.

• Chen-Fei, 1998. Study on the selection of 69 asexual tung tree families by canonical correlation analysis. Forest Research 11: 518–522.

• Duke, J.A., 1983. Aleurites montana (Lour.) Wils. In: Duke, J.A. (Editor). Handbook of energy crops. [Internet] http://www.hort.purdue.edu/ newcrop/duke_energy/ Aleurites_montana.html. January 2007.

• Foster, L.J., 1962. Recent technical advances in the cultivation of the tung oil tree, Aleurites montana, in Nyasaland. Tropical Agriculture 39: 169–187.

• National Early Warning Unit, 1997. Malawi Agricultural Extension Bulletin 1996/1997. Planning division, Ministry of Agriculture and Irrigation, Lilongwe, Malawi. 58 pp.

• Purseglove, J.W., 1968. Tropical Crops. Dicotyledons. Longman, London, United Kingdom. 719 pp.

• Radunz, A., He, P. & Schmid, G.H., 1998. Analysis of the seed lipids of Aleurites montana. Zeitschrift für Naturforschung 53: 305–310.

• Sengers, H.H.W.J.M. & Koster, A.C., 1998. Tungolie [Tung oil]. Landbouw Economisch Instituut (LEI/DLO), the Hague, Netherlands. 115 pp.

• Spurling, A.T. & Spurling, D., 1974. Effect of various organic and inorganic fertilizers on the yield of Montana tung (Aleurites mintana) in Malawi. Tropical Agriculture 51: 8–11.

• Wit, F., 1950. Chinese houtolie [Chinese wood oil]. In: van Hall, C.J.J. & van den Koppel, C. (Editors): De landbouw in de Indische Archipel [Agriculture in the Indonesian Archipelago]. Vol. 3. van Hoeve, the Hague, Netherlands. pp. 621–653.

Sources of illustration

• Aguilar, N.O. & Ong, H.C., 2001. Vernicia Lour. In: van der Vossen, H.A.M. & Umali, B.E. (Editors). Plant Resources of South-East Asia No 14. Vegetable oils and fats. Backhuys Publishers, Leiden, Netherlands. pp. 142–146.

Author(s)

• L.P.A. Oyen, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Oyen, L.P.A., 2007. Vernicia montana Lour. In: van der Vossen, H.A.M. & Mkamilo, G.S. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands.

Accessed 18 December 2024.

• See the Prota4U database.