1395

3: Dye and tannin-producing plants

Caesalpinia sappan L.

Sp. Pl. 1: 381 (1753).

LEGUMINOSAE

2n = 24

Biancaea sappan (L.) Todaro (1876).

Sappanwood, Indian redwood (En). Sappan (Fr). Indonesia: kayu secang, soga jawa (Javanese), secang (Sundanese). Malaysia: sepang (general). Philippines: sibukao (Tagalog, Bisaya), sapang (Tagalog, Bisaya, Ilokano). Burma: teing-nyet. Cambodia: sbaèng. Laos: faang dèèng. Thailand: faang (general), faang som (Kanchanaburi), ngaai (Karen, Kanchanaburi). Vietnam: vang nhuôm, tô môc.

The origin of sappanwood is not certain, but it is thought to be in the region from central and southern India through Burma, Thailand, Indo-China and southern China to Peninsular Malaysia. It is cultivated and naturalized in many parts of Malesia (Indonesia, the Philippines, Papua New Guinea) and also in India, Sri Lanka, Taiwan, Solomon Islands, and Hawaii.

The wood of sappanwood was a major source of a red dye up to the end of the 19th Century. It is still used for dyeing but only on a small scale. Cotton, silk, wool and matting can be dyed with it. In Indonesia, the wood is also used for colouring drinks pink. The fruits contain tannin and were used in the past to prepare a black dye together with iron. Sappanwood is also used as medicine in India, Indonesia and the Philippines. A decoction of the bark and wood is used as a cure for tuberculosis, diarrhoea, and dysentery, as an astringent and as a vulnerary. The seeds serve as a sedative. In the Philippines, the wood is a primary source of firewood. It is also made into small handicrafts, violin bows, and wooden nails. The species is often planted as living fences. Owing to the ease with which it grows and its dense growth habit, it is used for defining the boundaries of land and for protecting timber plantations against grazing animals. The leaves are used to hasten ripening of fruits such as bananas and mangoes.

Not much attention has been given to sappanwood since its use as a dyewood declined at the end of the 19th Century. In Indonesia 3.06 t of wood were used for medicinal purposes in 1983 and 3.37 t in 1984, and a very small amount (ca. 60 kg) was exported in 1983. In the Philippines, it is planted by smallholders for use as firewood but statistics are not available. This species is no longer traded internationally.

A red dye, called sappanin, is extracted from the heartwood. The wood also contains brazilin, an important compound of the red dye from brazilwood (Caesalpinia echinata Lamk). The name brazilwood, referring to the bright red colour like glowing coals, was originally used for sappanwood until the discovery of Caesalpinia echinata in about 1500 in the region now called Brazil. The dye from brazilwood is considered superior. The wood is rasped to a coarse powder, moistened with water and allowed to ferment for a few weeks to increase the colouring power of the dye. The fermented wood is boiled in water. The dye is also extractable with alcohol and other organic solvents. The extractable dye amounts to 20% of the oven-dry weight of the heartwood.
A group of phenolic compounds called homoisoflavonoids appear to be responsible for the medicinal activity of bark and wood. The stem and leaves contain alkaloids and tannins, abundant saponin and phytosterol. The fruits contain ca. 40% tannin, which is suitable for the production of light leather goods.
Freshly cut sappanwood is light orange in colour. The colour deepens to dark red upon prolonged exposure to sunlight and/or air. Prolonged boiling intensifies the colour of the dye.
The sapwood ring is very narrow and light coloured, the heartwood makes up to 90% of the total volume. The pith is distinct and yellowish. The growth rings are distinct. The wood is straight grained with a fine to moderately fine texture, fairly heavy (600—780 kg/m³), hard and lustrous. It is difficult to dry and susceptible to warping and collapse, but moderately easy to work; it takes a high finish, and is tough and resistant to termite attack. The energy value is about 25 000 kJ/kg.

A small shrubby tree, 4—8(—10) m tall; roots fibrous and wiry, lacking nodules, dark coloured; trunk up to 14 cm in diameter; bark with distinct ridges and many prickles, greyish-brown; young twigs and buds hairy, brownish. Leaves stipulate, bipinnate, up to 50 cm long, with 8—16 pairs of up to 20 cm long pinnae; pinnae with prickles at the base and with 10—20 pairs of oblong, 10—20 mm x 6—10 mm long, subsessile leaflets, very oblique at base, rounded to emarginate at apex. Flowers in terminal panicles, 2—2.5 cm wide, yellow, 5—merous; sepals glabrous, petals pubescent, the superior one smaller; stamens 10, filaments woolly-hairy in the lower half; ovary superior, pubescent. Fruit a dehiscent pod, oblong—obovate, 7—9 cm x 3—4 cm, strongly flattened, shiny and glabrous with curved beak at apex, yellowish-green when young maturing to reddish-brown, 2—5—seeded. Seeds ellipsoid, flattened, 18—20 mm x 10—12 mm, brown.

Usually mature pods burst open in the dry season and scatter the seeds, which remain dormant until the start of the rainy season. Seeds germinate immediately if enough moisture is available. Flowering can occur after one year of growth, and in Indonesia pods are produced 13 months after planting. Initially sappanwood grows straight but after having attained about 2.5 m height, the branches start to droop and entwine with the branches of nearby trees to form thickets, generally free from undergrowth. After the tree is felled the stump sprouts profusely within two weeks. Flowering is usually in the rainy season, fruiting about 6 months later.

Under natural conditions sappanwood grows mostly in hilly areas with clayey soil and calcareous rocks at low and medium altitudes. In Peninsular Malaysia it grows best on sandy riverbanks. It does not tolerate too wet soil conditions. Sappanwood is reported to tolerate an annual precipitation of 700—4300 mm, an annual mean temperature of 24—27.5°C, and a soil pH of 5—7.5.

Sappanwood can be propagated by seeds and renewed by coppicing. Germination occurs readily, but is enhanced by dipping the seeds wrapped in cotton cloth into boiling water for 5 seconds. Germination rate is then about 90%. Usually the plants are cultivated in the shade of trees in the forest or in the forest border.

No serious diseases and pests have been reported, although fungi such as Auricularia auricula—judae and Meliola caesalpiniae can attack the trees.

For use as a dyewood the tree must be harvested every 6—8 years, to allow the heartwood to become fully developed, for firewood it may be harvested every 3—4 years when the trunk has attained a diameter of 5—6 cm. The tree is cut about one metre above the ground to allow sprouts to grow from the stump. Harvesting is done manually with a machete; prickles are easily removed by brushing with the blunt edge of the machete.

The dye liquor may be used immediately after the wood has fermented or is evaporated to powder, which can be stored for future use. The mordants used (aluminium acetate, stannic salts, oxalic acid, etc.) determine the final colour of the cloth, which can vary from shades of red to pink, violet and brown. Sometimes the dye is used in mixtures, for instance with indigo for purple colours and with turmeric and iron sulphate to produce a rich maroon.

A revival of the use of sappanwood as a dye source will not happen in the immediate future since synthetic dyes are cheaper to produce, brighter, more lustrous and more permanent. However, people may once again turn to natural dyes in the far future, for instance because of environmental problems with synthetic dyes, and sappanwood would then provide a renewable resource.
Sappanwood may have better prospects as a medicinal plant, and as a producer of fuelwood with high energy value. The prospects for the beautiful wood are good.

Duke, J.A., 1981. Handbook of legumes of world economic importance. Plenum Press, New York. pp. 30—32.
Fuke, C., Yamahara, J., Shimokawa, T., Kinjo, J.E. & Tomimatsu, T., 1985. Two aromatic compounds related to brazilin from Caesalpinia sappan. Phytochemistry (Oxford) 24(10): 2403—2406.
Serrano, R.C., 1984. Sibukao, excellent fuelwood. The PCARRD Monitor, Los Baños, Laguna, the Philippines, 12(6 & 7): 9—10.
Zerrudo, J.V., 1985. Sibukao (Caesalpinia sappan L.) a multipurpose tree. Diamond Jubilee Professorial Lecture. University of the Philippines at Los Baños, College Laguna, the Philippines. 23 pp.

J.V. Zerrudo

Zerrudo, J.V., 1991. Caesalpinia sappan L.. In: Lemmens, R.H.M.J. and Wulijarni-Soetjipto, N. (Editors): Plant Resources of South-East Asia No 3: Dye and tannin-producing plants. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea