Uncaria gambir (PROSEA)
Uncaria gambir (Hunter) Roxb.
- Protologue: Hort. Beng.: 86 (1814).
- Family: Rubiaceae
- Chromosome number: 2n= unknown
- Gambier, white cutch, pale catechu (En)
- Indonesia: gambir (general)
- Malaysia: gambir, gambier, kancu.
Origin and geographic distribution
The origin of gambier is uncertain. Rumphius reported its cultivation in the Moluccas in the middle of the 18th Century. It is cultivated in Peninsular Malaysia and Indonesia (Sumatra, Java, Bali, Kalimantan, Moluccas). Plants which are probably truly wild have been collected in Sumatra and Borneo.
The resinous substance extracted from the leaves and young branches of gambier is crystallized and traded in small cubes or blocks. It has three major uses: for tanning leather; as a stimulant chewed with betel nut ( Areca catechu L.), lime and the leaf of Piper betle L.; and as a medicine. Minor uses are as a dye in the traditional batik industry and for dyeing silk black; as a clearing agent for beer, and as a remover of scale from boilers. The leaves are also used fresh for medicinal purposes. As a medicinal plant, gambier is used as an astringent. An infusion of fresh leaves is given against diarrhoea, dysentery, and as a gargle for sore throats. Gambier is also used as a styptic, and against inflamed gums. It is applied externally in lotions for burns and in a paste for scurf. External application against sciatica and lumbago is reported from Borneo.
Production and international trade
In the period 1920-1940 the total production of gambier in Indonesia was approximately 15 000 t/year, of which one-third was exported primarily to Britain and the United States, with smaller markets in Germany, the Netherlands and Singapore. Peninsular Malaysia was producing less during this period, exporting about 3000 t/year, half of which went to India. The market price of the finished product, i.e. small cubes or blocks, fluctuated between US$ 100-400/t during this period. In Indonesia, about 8 large estates with a total area of 1750-2000 ha accounted for most of the exports, and many smallholdings produced gambier for local consumption; some 6000-10 000 ha were probably involved.
After the Second World War gambier lost most of its importance as an export product. In tanneries in Europe and the United States, it was largely replaced by other vegetable tanning materials and syntans. In South-East Asia gambier has never been used on a large scale as a tannin. However, gambier has continued to have some local importance as a masticatory, medicinal and dye plant. No recent production data are available, but production must be considerable as block gambier is still available in fairly large quantities on Indonesian markets, for instance in central Java and Kalimantan. In 1985, about 1200 t of gambier worth approximately US$ 1 million was exported from Indonesia. The main exporting areas are Sumatra and Riau, with average exports in 1985 and 1986 of 340 and 620 t/year, respectively.
The tannins in the leaves of gambier belong to the proanthocyanidin type. The leaves contain catechin, poorly soluble in cold water but readily soluble in hot water, and catechu-tannic acid which is soluble in cold water. Catechu-tannic acid is not desirable in gambier used for chewing and is removed. Consequently gambier is manufactured in different ways; the final product is either suitable for tanning purposes or for betel chewing. Block gambier used for tanning in Europe contained 35-40% tannin. With modern methods of extraction, much higher tannin percentages have been obtained. Now block gambier containing up to 65% catechin and lacking catechu-tannic acid (thus suitable for chewing) can be produced. The maximum yield of crude gambier is 6.5% of the leaf weight.
When used alone in tanning, gambier produces a rather spongy leather. However, it is very suitable for both light and heavy leathers if mixed or blended with other tanning materials such as wattle ( Acacia spp.) extract or myrobalans ( Terminalia spp.). Gambier is also suitable for preserving fishing nets.
The tannin has algicidal properties, as well as antibacterial and antifungal activity. Antiherpetic activity has also been reported. Several indole alkaloids, some unidentified, have been extracted from leaf materials. These may have a narcotic effect.
Gambier is used for "soga batik" dyeing, but the brownish colour only develops if a diazonium salt is added.
The seeds are very light; 1 kg contains about 25 000 000 seeds.
- A liana often cultivated as a straggling shrub, with square young stems and erect main stems bearing horizontal branches with recurved hooks (modified peduncles of inflorescences).
- Leaves opposite, subcoriaceous, and entire, ovate to (broadly) elliptic, (6-)9-12(-15) cm × (3.5-)5-7(-8) cm, rounded to subcordate at base, acute at apex, glabrous, with 5-6 pairs of lateral nerves, raised below and with hairy domatia.
- Flowers in heads on horizontal plagiotropic branches; heads (3.5-)4-5 cm in diameter (across corollas), receptacle densely hairy, interfloral bracteoles absent; pedicel up to 3 mm long, hypanthium 1-2 mm in diameter, densely yellow-brown hairy; calyx 3-4.5 mm long, with 5 trigonal, 1-2 mm long lobes, finely pubescent, persistent; corolla hypocrateriform with 8-10(-12) mm long tube, exterior sparsely to densely pubescent, and 5 oblong, 2-3 mm long lobes, exterior densely yellow-brown sericeous, quickly falling off from the heads; stamens 5, adnate to the corolla; ovary inferior, style exserted 5-7 mm, stigma obovoid to clavate, ca. 2 mm.
- Fruiting head (50-)60-80 mm in diameter, fruitlets (capsules) 14-18 mm long, sparsely pubescent and crowned by the calyx, many seeded; fruit stalks up to 20 mm long.
- Seeds very tiny, silvery-grey.
Growth and development
Seeds take about 2 weeks to germinate. After about 10 weeks, seedlings are 3-4 cm tall. The first harvest is usually obtained when plants are 12 to 18 months old. During harvesting the orthotropic shoots are topped at about 2 m, resulting in reiteration of shoots developing from dormant buds below the plagiotropic shoots. The climbing plant can thus be induced to make a shrub-like form. Plantations are usually maintained for (8-)12-15(-20) years. Gambier plants have been recorded to reach an age of 60 years.
Other botanical information
Uncaria gambir is frequently confused with other related species, particularly Uncaria callophylla Blume ex Korth., Uncaria acida (Hunter) Roxb. and Uncaria elliptica R. Br. ex G. Don (synonym: Uncaria dasyoneura Korth.). These species have been reported to have been incidentally used in gambier production.
Recently a plant from Sumatra with denser foliage, called "Uncaria payakumbuh", has been mentioned as a gambier source. The catechin content of this plant is somewhat less than that of "true" gambier.
Gambier can be cultivated in areas with high rainfall throughout the year. Usually it grows well at altitudes of 0-200 m, but cultivation up to 1000 m is possible. The plant does not tolerate waterlogging. Gambier has no special soil requirements, but it is usually cultivated on soils with a rich humus layer, or containing much clay. Wild gambier is most commonly found in secondary forest. It does not occur in dry regions or at higher altitudes.
Propagation and planting
Propagation is usually by seeds. The very small and light seeds rapidly lose their viability. Seeds are usually sown in seed-beds. To achieve a uniform dispersal, the seeds are often blown into the seed-beds. On slopes, the vertical walls of terraces are sometimes used as seed-beds and the seeds are blown to the walls. Horizontal seed-beds need protection from sun and rain. Usually seedlings are transplanted into the field 2-7 months after sowing, depending on the region. Planting distance is 2 m × 3 m or 3 m × 3 m. The seedlings are usually planted in the edge of a hole, and the hole is not filled with soil.
Gambier may be propagated vegetatively by cuttings, by layering, or by grafting. Vegetative methods of propagation usually result in an advanced first harvest. However, these plants are recorded to contain less tannin at harvest.
Gambier can be intercropped as a cash crop in rubber and oil palm plantations.
No special practices are necessary except weeding during the first year. Fertilizers are usually not applied. Although gambier is a natural climber, no support is needed for cultivated plants when the crop is managed properly.
Diseases and pests
In smallholdings, gambier is usually free from serious diseases and pests. However, in large monocultures plagues of caterpillars and beetles have been reported. A mite causes monstrous inflorescences and also attacks the leaves.
The orthotropic main shoots are cut back to 1.3-1.5 m from the ground, and the shoots are dried, usually in the shade, and are bundled and transported to the factory. The first harvest takes place after about 1.5 years with plants grown from seed. Improved cultivation methods allow harvesting to take place 9 months after sowing, even when plants have been grown from cuttings. When grown in pure stands, harvesting is usually twice per year. However, when the plant is grown as a cash crop between rubber or other crops, it can be harvested up to 4 times a year.
There is a great variation in yield, depending on the harvesting frequencies. Generally, smallholdings obtain a yield of block gambier of 180-200(-700) kg/ha per year, whereas larger plantations have achieved 1000-3000 kg/ha per year.
Handling after harvest
The most widespread method of fabrication of gambier is the so-called Chinese method. Crushed leaves and twigs are boiled in water for about 1 hour, after which the plant fragments are removed from the decoction. The decoction is further concentrated by boiling and evaporation for about 3 hours. The concentrate is transferred to smaller containers, seeded with catechin crystals and allowed to solidify into a treacle-like mass. To make "cake" gambier, this mass is poured into simple moulds and after about 12 hours it solidifies into a solid cake which is cut into blocks and sun-dried to form sticky red-brown blocks. Cube gambier for chewing is made by pouring the decoction into bottomless wooden frames placed on an absorbant cloth which removes the water. By simple manipulation of strings the mass is further divided into cubes. Further drying at low temperatures takes about 10 days.
Local production still occurs as an unsophisticated modification of the above process using bamboo as a mould. The bamboo is removed and the mass is cut into disks, often with a fabricant stamp. Such products, however, have not been seen on local markets recently. Larger plantations use a modification of the Chinese method with more efficient ovens and equipment. Modern methods of extraction have been developed in Indonesia. Leaves of gambier are extracted by steaming or boiling, and then pressed with a hydraulic press at a pressure of 18 000 kg/cm2, after which they are dried for 3-4 days. The best quality of gambier is obtained by steaming for 5 minutes. The catechin content of the product is higher when steaming is used rather than boiling (up to 65% as compared with up to 55%).
As a tanning material, gambier is now far less important than it was at the beginning of the 20th Century. Gambier has never been used on a large scale in local tanneries in South-East Asia. However, it has good prospects as a source of tanning material. Gambier produces leather of good quality, especially when mixed with other vegetable tanning materials. The plant is easy and fast to grow and the leaves contain tannin which ensures a regular harvest without destroying the crop.
It maintains importance as a masticatory in South-East Asia, especially for older people; however, younger people are less addicted to betel chewing.
Research priorities should focus on selection and breeding of good quality plants. Cultivated plants are very similar to wild plants and there do not seem to be any different cultivars. Gambier may also be useful in agroforestry systems.
- Backer, C.A. & Bakhuizen van den Brink, R.C., 1965. Flora of Java. Vol. 2. Noordhoff, Groningen, the Netherlands. p. 301.
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- Sastrapradja (Editor), 1978. Tanaman industri [Industrial crops]. National Biological Institute, Bogor, Indonesia. 132 pp.
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