Dipteryx odorata (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Dipteryx odorata (Aublet) Willd.

Family: Leguminosae

Synonyms

• Baryosma tonga Gaertner,
• Coumarouna odorata Aublet,
• Dipteryx tetraphylla Spruce ex Benth.

Vernacular names

• Tonka bean (En).

• Coumarou (Fr)

Distribution

Indigenous to South America, especially along the tributaries of the Orinoco in Brazil, Colombia, the Guianas and Venezuela. Occasionally introduced and sometimes cultivated elsewhere.

Uses

After the seeds (beans) have been soaked for several days in strong rum or alcohol (45-65%) and then dried they become pliable, show a heavy crystalline coumarin deposit on the testa and have an odour of new-mown hay. The cured beans contain about 8% water, 2-3% coumarin and 25% of tonka butter. The bean or its extract is used to perfume and flavour food, tobacco, soap and liqueurs. It is also used as a substitute for vanilla and as a fixing agent for dyes and perfumes. Medicinally the seeds are used as a tonic or narcotic and to cure diarrhoea, cough and schistosomiasis. The brown, close-grained timber is very hard, tough and durable and resistant to marine borers but difficult to work. It is a very suitable wood where resistance to pressure is required. The trees are also used for shade in cocoa. The bark of the tree yields a kino very similar to eucalyptus kino and containing about 40% of tannin.

Observations

• Tree, up to 40 m tall and trunk up to 1 m in diameter. Root system with a vigorous taproot to only 1 m depth, deeper-growing anchor roots and a dense surface mass of feeding roots.
• Leaves alternate, pinnately compound, leathery, glossy green; rachis flattened and winged; leaflets 3-6, opposite or alternate, elliptical but unequal-sided, up to 15 cm × 8 cm.
• Inflorescence a panicle with rose-violet flowers; calyx tube 4 mm long, 2 posterior sepals petaloid; corolla 10-12 mm long.
• Fruit drupaceous, ellipsoidal, 7-10 cm × 3-6 cm, indehiscent, pale yellow-brown; mesocarp pulpy; endocarp hard, enclosing a single seed.
• Seed usually wrinkled, 3-5 cm × 1-2 cm, dull mahogany, weighing about 3 g.

In the wild D. odorata occurs in tropical forest, often along river banks. It requires an annual rainfall of 1500-2750 mm and is grown up to 350 m altitude. It prefers humus-rich soils poor in calcium. Propagation is usually by seed, but is possible by cuttings as well. Initial spacing is 3 m × 3 m, thinning after 10 years. When about 2 m tall the trees are topped to induce branching. Normally flowering and fruiting starts 7-10 years after planting, but good crops are only obtained every 2-3 years. Pollination is by insects. Diseases and pests are never serious; only bats pick the fruits to eat the pulpy flesh. Yield of dried beans per tree is normally 0.5-1 kg annually, but up to 25 kg can be obtained. Two commercial types are recognized: the Angostura-Venezuelan type and the Brazilian or Para type. The main producer of tonka beans from wild trees is Venezuela, followed by Brazil and Colombia. Production has decreased because of competition from synthetic coumarin and vanillin. To a lesser extent, seeds of other Dipteryx species are used similarly as D. odorata. As a source of natural flavour, D. odorata is possibly of interest for South-East Asia. Experiments in the early 1900s in Indonesia and Singapore were promising.

Selected sources

• Burkill, I.H., 1935. A dictionary of the economic products of the Malay Peninsula. 2 volumes. Crown Agents for the Colonies, London, United Kingdom. 2402 pp. (slightly revised reprint, 1966. 2 volumes. Ministry of Agriculture and Cooperatives, Kuala Lumpur, Malaysia. 2444 pp.).

• Duke, J.A., 1981. Handbook of legumes of world economic importance. Plenum Press, New York, United States. 345 pp.

• Heyne, K., 1927. De nuttige planten van Nederlandsch 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, the Netherlands/Indonesia. 1660 pp.).

• Mansfeld, R., 1986. Verzeichnis landwirtschaftlicher und gärtnerischer Kulturpflanzen (ohne Zierpflanzen) [Register of agricultural and horticultural plants in cultivation (without ornamentals)]. Schultze‑Motel, J. et al., editors 2nd edition, 4 volumes. Springer Verlag, Berlin, Germany. 1998 pp.

• Purseglove, J.W., 1968-1972. Tropical crops. Longman, London, United Kingdom. Dicotyledons, 2 volumes (1968), 719 pp. Monocotyledons, 2 volumes (1972), 607 pp.

Authors

P.C.M. Jansen