Acacia catechu (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Acacia catechu (L.f.) Willd.

Protologue: Sp. Pl. 4th ed., Vol. 4(2): 1079 (1806).

Family: Leguminosae

Chromosome number: 2n= 26

Synonyms

• Acacia chundra Willd. (1806).

Vernacular names

• Cutch tree, catechu tree (En)
• Acacie au cachou (Fr)
• Burma: sha
• Thailand: sisiat nua (central), sa-che (Shan, Mae Hong Son), sisiat (northern).

Origin and geographic distribution

Cutch tree is distributed in the southern Himalayas of Pakistan, northern India and Nepal, south to Andhra Pradesh in India, and east to Burma and Thailand. It is sometimes planted in Indonesia (Java), Thailand, Burma and India.

Uses

A substance called cutch, which is marketed as a solid extract, can be isolated from the heartwood. Depending on the way of processing, several products for different purposes can be obtained from crude cutch. In India and Burma the dark "catechu" or "Pegu cutch" is used to tan heavy hides into sole leather, often in a mixture of tan-stuffs. Catechu extract is also used for preserving fishing nets and ropes, and for dyeing cotton, silk, canvas, paper and leather a dark-brownish colour, and also as viscosity modifier in on-shore oil wells. The crystalline portion of a concentrated decoction of the wood, called "katha" or "kath", is much used in betel chewing together with the leaf of Piper betle L., and as an astringent for medicinal purposes. A third form of cutch is the crystalline deposit sometimes found in cavities of the wood, known in India as "khersal". It is used for medicinal purposes, especially for the treatment of cough and sore throat. The bark is said to be effective against dysentery, diarrhoea and in healing wounds. The seeds have been reported to have an antibacterial action.

The wood is a useful timber, used for house posts, agricultural implements, wheels, etc. It is very strong, hard, durable and not attacked by white ants or teredos. The wood is an excellent firewood and one of the best woods for charcoal. Spent chips left over after the extraction of katha and cutch can be used for the manufacture of hardboards. The tree is a host for lac insects. Fresh leaves and small lower branches are eaten by cattle.

Production and international trade

A trade in cutch between India and China existed from the earliest days of seaborne trade. As "terra japonica", a product thought to be a mineral, cutch was imported in the 17th Century in Europe for medicinal purposes.

In India and Burma, the cutch tree is considered as a valuable tree; there is a great demand for cutch and katha. Statistics on the production of katha and cutch are not easily obtained, and vary greatly from 7000-9000 t/year in 1976, to as much as 40 000 t/year in 1974 in India. Exports from India were estimated as 215-430 t per year in the 1970s. In Thailand crude cutch is produced on a small scale for local uses and for export. In Indonesia (Java) about 24 000 ha of land was made available for cutch tree plantations in 1959, but there is no information on how much was really planted with this species. In Thailand plantations cover about 3300 ha.

The name "cutch" is also used for mangrove extract, and figures on production and international trade of cutch sometimes also refer to this product.

Properties

The average yield of katha is 3-4.5% of the weight of the heartwood, and the average yield of cutch is 6-8%. The tannin content of cutch is usually 55-60%. When used alone the tannin yields a harsh leather apt to contain yellow stains. Cutch contains 25-35% catechutannic acid, 2-10% catechin (C₁₅H₁₄O₆), and small proportions of catechu red, quercetin and gum. Katha predominantly consists of a mixture of catechin isomers; the catechin content averages 55% in katha of good quality. Catechin is also found in gambier from Uncaria gambir Roxb., which provides a similar product used in betel chewing in South-East Asia.

The tannin has shown algicidal activity when tested in ponds. Cutch has been found to be effective against liver diseases; this property has been attributed to the presence of the d-form of catechin called (+)cyanidanol-3.

The sapwood is sharply distinct from the heartwood, and is yellowish-white or yellow. The heartwood is light red to reddish-brown, darkening on exposure and is very strong and hard. The wood is comparatively heavy with a density of 880-1000 kg/m³ at 15% moisture content. The timber is characterized by brown tracts of paratracheal parenchyma, distinct narrow lines of terminal parenchyma and by the presence of white specks of a crystalline deposit. The timber needs long seasoning, and is fairly difficult to saw.

Seed weight is about 65 g/1000 seeds.

Description

• A small or medium-sized thorny tree, up to 15 m tall. Bark dark grey or greyish-brown, peeling off in long strips, or sometimes in narrow rectangular plates, brown or red inside. Branches slender, puberulous when young but glabrescent, with 2 curved, ca. 8 mm long prickles at the base of each petiole.
• Leaves bipinnately compound with 9-30 pairs of pinnae, and a glandular rachis; leaflets 16-50 pairs, oblong-linear, 2-6 mm long, glabrous or pubescent.
• Flowers in 5-10 cm long axillary spikes, 5-merous, white to pale yellow, with a campanulate 1-1.5 mm long calyx, and a 2.5-3 mm long corolla; stamens numerous, far exserted from the corolla with white or yellowish-white filaments.
• Fruit a strap-shaped pod, 5-8.5 cm × 1-1.5 cm, flat, tapering at both ends, shining brown, dehiscent, 3-10-seeded.
• Seeds broadly ovoid.

Growth and development

Germination starts 5-7 days after sowing. The tree starts flowering and producing pods when 5-7 years old. In Burma and Thailand it usually flowers in August and September, and the pods become mature in January and February.

Investigation on growth in Nakhon Ratjasima Province in Thailand showed a mean annual increment in girth of the bole of 2.5-4 cm. In India a mean annual increment of 3.2 cm has been reported in Himalayan trees and 4.3 cm in trees from Darjeeling Tarai.

Other botanical information

Acacia chundra is sometimes considered as a separate species, sometimes as a variety of A. catechu, differing from the typical A. catechu in having glabrous leaves, calyces and rachises and in having heavier wood. Sometimes var. catechuoides Prain is distinguished, having glabrous calyces but puberulous rachises and also heavy wood.

Ecology

Cutch tree occurs naturally in mixed deciduous forests and savannas of lower mountains and hills, up to 1500 m altitude. It is especially common in the drier regions on sandy soils of river banks and watersheds. It can be grown in the more humid climates of South-East Asia at altitudes from sea-level to about 300 m, as cultivation in Java shows, but it is intolerant of clay soils.

Propagation and planting

Plants can easily be propagated by seed and by cuttings. Before sowing it is recommended to put the seeds in boiling water and to leave them to cool in the water for 24 hours. In India seeds may be sown in early summer, in a 0.5 cm deep seed-bed. The beds should be watered thoroughly. Usually the seedlings are transferred to plastic bags, and planted in the field when they are 3-6 months old or 30-50 cm high. Plant spacing is 4 m × 6 m or 2 m × 4 m. In wet regions the seed may be sown directly in the field.

Husbandry

Weeding is essential, especially when plants are still young. Protection against fire is necessary, especially in the drier parts of India, Burma and Thailand. The plants should also be protected against grazing animals.

Diseases and pests

In India, parasitic plants of the genus Cuscuta L. may kill plants, and hemiparasitic plants of the genus Loranthus Jacq. may damage trees. Root rot can be caused by the fungus Ganoderma lucidum. Other fungi may cause rot, too. Insects reported to attack cutch tree in Thailand include Bothogonia spp., seed-boring beetles such as Bruchidius terranus and Bruchus billineatopygus, and the leaf-eating insect Dasychira mendosa. Rodents are also reported to damage trees.

Harvesting

Trees with a girth of 60-120 cm are generally preferred for cutch production. The wood can be harvested when the trees are 30 years old in good sites, 50 years old in moderate sites, and 60 years old in poor sites. The trees are felled and transported to factories.

Yield

For maximum heartwood production there should be about 560 trees/ha at 10 years of age. In 60-year-old plantations in India the yield of heartwood in good sites is 75 m³/ha, in moderate sites 63 m³/ha, and in poor sites 50 m³/ha. In these plantations the yield of cutch can be estimated at 6 t/ha, 5 t/ha and 4 t/ha, respectively.

Handling after harvest

The wood of freshly felled trees yields more cutch than dried wood. After felling, the bark and sapwood are removed, and the heartwood is converted into chips. In India the chips are extracted with water in extractors made of copper or wood, but vessels of aluminium and stainless steel are also suitable. After heating for about 2 hours, the chips are removed and extracted in a new bath of water. Then the extract is evaporated and cooled for crystallization of katha, which is separated by filtering. To obtain cutch the aqueous liquor is further concentrated in evaporators to a consistency at which it solidifies on cooling. In this way advantage is taken of the fact that cutch is soluble both in cold and hot water, whereas katha is only sparingly soluble in cold water. Cutch and katha are marketed in the form of tablets.

In Thailand the chips are extracted by boiling in vessels 7 times; this takes about 9 hours. Concentrated extract of correct consistency is rolled into balls and dried.

In dyeing cotton, the material is steeped for about one hour in a boiling solution of cutch, to which copper sulphate has been added. Afterwards it is transferred to a bath containing sodium bichromate. The dye is very fast to light, acids and alkalies.

Prospects

In India, the number of katha factories has been increasing rapidly in the period 1980-1990. Sustained supply of the raw material is a problem. In Thailand, the demand of tanning agent is very high, and although cutch does not hold a high position as a tan-stuff, cutch tree is easy to grow and might be promising. As a multipurpose tree, it deserves more study to verify the possibilities for cultivation in the wetter climates of South-East Asia.

Literature

• Anonymous, 1990. Report on chemical processing and utilization of Acacia catechu Willd. Minor Forest Products Sub-division. Royal Forest Department, Thailand.
• Bhatnagar, S.S. (Editor), 1948. The wealth of India. Raw materials. Vol. 1. Delhi. pp. 9-13.
• Jain, P.P., 1980. A note on the production of katha and cutch in India. Indian Forester 106: 569-573.
• Singh, S.P. & Jain, R.C., 1987. Yield of heartwood in Acacia catechu, khair, for use in katha manufacture. Indian Forester 113: 404-408.

78, 115, 162, 234, 300, 369, 649. (timbers)

Authors

W. Subansenee