Terminalia chebula (PROSEA)

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Plant Resources of South-East Asia Introduction

List of species

Terminalia chebula Retz.

Protologue: Obs. Bot. 5: 31 (1788).

Family: Combretaceae

Chromosome number: 2n= variously recorded as 14, 24, 26, 36, 48, 72

Synonyms

• Terminalia parviflora Thwaites (1854),
• Terminalia zeylanica van Heurck & Müll.-Arg. (1870),
• Terminalia tomentella Kurz (1873).

Vernacular names

• Chebulic myrobalan, chebulic myrabolan, black myrobalan (En)
• Myrobalan noir, myrobolan noir (Fr)
• Malaysia: manja lawai, manja puteri (unripe fruits), manja patut (ripe fruits)
• Cambodia: srâmââ, srâmâr, sa mao tchet
• Laos: som, 'som²moⁱkhôk
• Thailand: maa-nae (Karen, Chiang Mai), samo thai (central), maak-nae (Karen, Mae Hong Son)
• Vietnam: cà lich, chiêu liêu xanh.

Origin and geographic distribution

Chebulic myrobalan occurs naturally from the sub-Himalayan region of Nepal and northern India, through India to Sri Lanka, Burma, Thailand, Indo-China and southern China. It has been introduced to Singapore, where it failed, but it was planted successfully in the botanical garden in Bogor, Java.

Uses

The fruits are rich in tannin, and are used on a large scale in India in the leather industry, usually combined with syntans and with other vegetable tanning materials such as black wattle (Acacia mearnsii De Wild.), avaram (Cassia auriculata L.) and Ceriops tagal (Perr.) C.B. Robinson. Chebulic myrobalan is used in the production of sole leather, and also in a last tannage after chrome tanning to give the leather weight and a fast colour. An extract is suitable for pretannage of cattle hides. A yellow dye can be prepared from the fruits plus alum; a black dye and ink can be prepared from the fruits plus iron. Myrobalans are also used as a mordant for the basic aniline dyes.

The fruits are edible and have numerous medicinal properties: laxative, stomachic, tonic, and alterative. They are often used in combination with emblic myrobalan (Phyllanthus emblica L.) and beleric myrobalan (Terminalia bellirica (Gaertner) Roxb.). They show antibacterial and antifungal activity, and are used to cure inflamed gums and as a relief in asthma.

The wood is used as construction timber and for furniture, carts and implements, but is not of much value.

Production and international trade

India is by far the main producing country. The production of dried fruits in 1981 was estimated at more than 100 000 t. Only a fraction (about 20%) of this was exported, as dried fruits, complete or crushed, or as extract, not only to countries in the region, but also to Europe and the United States. In trade, fruits are usually known by place of origin, those from Salem (India) considered the best.

Usually the tree is felled only when no longer important for fruit production. No data are available on the amounts of timber produced.

Properties

The dried fruit-pulp has an average tannin content of 30-32%, but the content varies considerably with the place of origin. Poor samples may register less than 20% tannin, good ones over 40%. Other parts of the plant such as roots, bark, wood and leaves, also contain tannin, but less than the fruits. The tannin is specified as an ellagitannin and is quite complex in nature. The major constituents are chebulagic acid, chebulinic acid and corilagin. Various proportions of products of hydrolysis are present, such as chebulic acid, ellagic acid and gallic acid. Myrobalans contain more sugar-like components than most other tanning materials, ca. 3-5%, which causes ready fermentation and satisfactory plumping of the hide in the early stages of tanning. They produce a brownish deposit on the leather, called bloom. The tannin is of a "mild" type and penetrates hides slowly. Used alone in tanning, myrobalans produce a soft, spongy, light yellow leather of poor wearing quality. They are usually mixed with tannins of the proanthocyanidin group, such as extracts of wattle and mangrove bark or quebracho wood, to give the leather more weight. Solid extracts as well as spray-dried myrobalan extracts are prepared, containing 58-60% tannin.

In the timber, the sapwood is sharply differentiated from the heartwood; it is yellowish-grey to grey, sometimes with a greenish tinge, whereas the heartwood is small, dark brown to reddish-brown, very hard and heavy to very heavy, with a density of about 880 kg/m³ at 12% moisture content. The timber is strong and tough, diffuse-porous, with interlocked grain; texture medium fine to fine, sometimes with curly grain, not durable in contact with the ground, but durable under cover; very difficult to season, and refractory to work.

Description

• A medium-sized, up to 25 m tall, deciduous tree of variable appearance, with a usually short cylindric bole of 5-10 m length, 60-80 cm in diameter at breast height; crown rounded, with spreading branches; bark dark brown, usually longitudinally cracked with woody scales; branchlets rusty-villous or glabrescent.
• Leaves alternate or opposite, thin-coriaceous, ovate or elliptic-obovate, 7-12 cm × 4-6.5 cm, rounded at base, obtuse to subacute at apex, entire, pubescent beneath; petiole up to 2 cm long, provided with 2 glands at the base of the leaf blade.
• Flowers in axillary 5-7 cm long spikes, simple or sometimes branched, about 4 mm across, yellowish-white and unpleasantly scented; calyx 5-lobed, corolla absent; stamens 10, exserted; ovary inferior, 1-celled.
• Fruit an obovoid or oblong-ellipsoid drupe, 2.5-5 cm long, faintly 5-angular, yellow to orange-brown when ripe, glabrous.
• Germination is epigeal, seedling with a long, fairly thin primary root, a short and thick hypocotyl, and glabrous cotyledons with 3 prominent and 2 less conspicuous veins.

T. chebula is divided into 2 varieties: var. chebula is a tree whereas var. nana Gagnep. is only a small shrub.

Growth and development

The germinative power of the seed is poor. Viability of the seed is retained for about 1 year. Seedling growth is comparatively slow, with 10-20 cm height attained by the end of the first season, and 25-50 cm by the end of the second season. Rate of growth is slow in later stages too. The flowers appear together with the new leaves after the tree has been leafless for several months. Fruits ripen some 8 months later, and fall soon after ripening.

Ecology

T. chebula occurs in mixed deciduous forest, extending into forests of comparatively dry types. It ascends to considerable elevations, up to 1500 m or even 2000 m. In Thailand and Burma, it is found together with teak. The species is found on a variety of soils, clayey as well as sandy. The tree is a light-demander, but withstands some shade in youth, and may benefit then from protection from the sun. It is fairly tolerant of frost and drought, and withstands fire, recovering well from burning and also from coppicing. Regeneration is usually poor, maybe because people harvest the fruit but also because of predation by animals.

Propagation and planting

The fallen fruits are collected and dried thoroughly first. Later the hardened flesh is removed. Fermentation of the stones gives the best germinative results, but clipping the broad end of the stone without damaging the embryo, followed by soaking in cold water for 36 hours gives good results too. Direct sowing is not advisable, because of the risk of predation and because the seeds germinate poorly. In India, seeds are usually sown in boxes or nursery beds before the rainy season, covered with soil, and watered regularly. A mere 20% success is reported. Transplanting from the nursery into the field can be done in the first or second rainy season. Shading is desirable in early stages in the nursery and after transplanting. Propagation by cuttings is possible, but less successful than transplanting nursery-raised seedlings into the field. In the forest, regeneration is facilitated by creating small gaps in the canopy, and this is supplemented by sowing seeds in the clearings.

Husbandry

The tree coppices well. The resulting shoots are 2-3 m long after 5 years.

Diseases and pests

The tree itself does not suffer from any serious disease or pest, although some defoliators have been reported. Fallen fruits are heavily predated by rodents and insects. The timber is attacked by borers.

Handling after harvest

Fruits are collected from the time they begin to turn yellow until they are quite yellow and ripe. They are sun-dried, avoiding wetting by rain, and they shrivel considerably during drying. Myrobalans are transported as whole fruits, or crushed without the stones, or as extracts.

For the extraction of tannin and the preparation of extracts the crushed fruits are infused for 8-10 hours with hot water in a series of vats. The tan-liquor is left to settle in a tank at a temperature of 60°C. To prevent fermentation, bleaching agents such as sodium hydrosulphite, alum and oxalic acid are often added; sometimes sodium acetate or formate are also added. The tan-liquor is concentrated in evaporators. The concentrated solution is fed into vacuum pans for preparing solid extracts, or through an atomizer for preparing spray-dried extracts. Various methods of reducing sludge formation in the tan-liquor and of utilizing the tannin more efficiently have been suggested. They include solvent-extraction of the fruits with chloroform or acetone, heating the extract at ca. 120°C, ultraviolet irradiation of the powdery extract, passing chlorine through the tan-liquor, and reducing the acidity of the liquor by treating it with salts and acetate buffers. The control of the pH of the tan-liquor seems to be the most promising method.

Whenever possible, the timber should be sawn when the wood is still green. Slow seasoning in protected and close-stacked piles is best to avoid cracking and splitting.

Prospects

T.chebula might be an interesting source of tanning material for South-East Asia. Because it is the fruit that yields the tannin, harvesting is not injurious to the trees, as is the case for many bark-yielding species. This species from mainland Asia is probably not suited to the climate of many parts of South-East Asia, unlike T. bellirica. However, as it has been grown for many years in the botanical garden in Bogor (Java), and as it has better tanning properties than the latter species, it might be worthwhile trying in cultivation.

Literature

• Chadha, Y.R. (Editor), 1976. The wealth of India. Raw materials. Vol. 10. Publications & Information Directorate, Council of Scientific and Industrial Research, New Delhi. pp. 171-177, fig. 54-56.
• Howes, F.N., 1962. Tanning materials. In: von Wiesner, J. (Editor): Die Rohstoffe des Pflanzenreichs. 5th ed. J. Cramer, Weinheim, Germany. pp. 210-215.
• Kochhar, S.L., 1981. Economic botany in the tropics. MacMillan Ltd., Delhi. pp. 374-375.
• Lecompte, O., 1969. Combretaceae. In: Tardieu-Blot, M.L. (Editor): Flore du Cambodge, du Laos et du Vietnam. Vol. 10. pp. 89-91.

163, 178, 392, 449, 468, 666. timbers

Authors

• J.M. Fundter, N.R. de Graaf & J.W. Hildebrand