1406

3: Dye and tannin-producing plants

Haematoxylum campechianum L.

Sp. Pl. 1: 384 (1753).

LEGUMINOSAE

2n = 24

Logwood, campeachy wood, blackwood (En). Bois de campèche, bois bleu, bois de sang (Fr).

Logwood is indigenous to Central America and the adjoining parts of South America. The plant was discovered by the Spanish on the shores of Campeche Bay in the Gulf of Mexico before 1525. It was introduced into the Caribbean where it widely naturalized, and into most parts of the Old World tropics, e.g. South-East Asia. It was introduced in Singapore in 1876. Logwood is cultivated on a very limited scale in Malaysia (Penang), Indonesia (Java), and the Philippines.

The main product of the tree is the heartwood; it is the logwood of commerce. This wood yields a series of dyes in darker tints of grey, brown, violet, blue and black. The dyes give a fairly permanent colour to several natural fabrics such as silk, wool, and sometimes cotton, but also to synthetics such as nylon and rayon. They may be used to dye leather as well as fur, feathers, paper and bone, and also in the manufacture of inks. Haematoxylin, the colouring agent of logwood, is a histological stain used for staining cell nuclei; alcoholic solutions serve as indicator for alkaloid titration.
Logwood may be grown in gardens as a hedge, or for its delicate foliage and fragrant flowers. These flowers are the source of a very good honey.
As timber, its use is largely limited by the irregularity of the trunk. The wood is strong but brittle; it is durable for use outdoors and in contact with the ground. It is sometimes used for furniture and fancy articles because it may be finished to a very smooth surface and takes a high polish. The wood burns readily. Medicinally it is a mild astringent; its value is attributed to the presence of tannin and haematoxylin. As an astringent and tonic it is prescribed in the form of a decoction and liquid extract. It is also useful against diarrhoea, dysentery, atonic dyspepsia and leucorrhoea. An ointment prepared from the wood is said to be useful against cancer and hospital gangrene. Haematoxylin has been shown to possess anti-inflammatory properties.
In South-East Asia, and also in India, logwood is only occasionally cultivated as hedge plant or ornamental, not for production of dyewood.

With annual exports of 100 000 t of wood, the logwood industry reached its peak during the latter half of the 19th Century. Logwood cutting is now a minor industry. To cheapen the cost of transport, logwood is mainly traded in the form of powdered extracts today.
The total logwood trade in 1990 is unlikely to be more than 500 t/year and might be much less. The main commercially producing countries are in the Caribbean area. France and Switzerland are the major importers. They are the main suppliers to the consuming countries in Europe, North America and Japan. In recent decades the price has fluctuated considerably.

Immediately after the tree has been felled, its heartwood is yellowish. On exposure to air it gradually acquires a bright reddish colour. Later it becomes dark purple with darker stripes, frequently tinged orange. Old wood may be coloured red. These different colours of the wood are caused by different substances. Fresh young wood contains about 10% colourless haematoxylin. This oxidizes to haematoxein, in pure form a dark violet crystalline substance with a green metallic lustre. In dyeing, the dyer produces haematoxein from haematoxylin. Haematoxylin is soluble in water, and is extracted from chips of the wood. Haematoxein is far less soluble in water and during the dyeing process it may be converted into iso-haematin, which is even less soluble.
Besides haematoxylin, heartwood contains tannin, resin, quercetin, traces of volatile oil, oxalic acid, and acetic acid. The wood is very hard and heavy, with an air-dry weight of 950—1085 kg/m³. The wood is compact, the grain interlocked, the texture is coarse but fairly even. It has an agreeable odour resembling violets, and a sweet astringent taste. The sapwood ring is thin, white or yellowish, and does not contain haematoxylin.

A small, bushy tree up to 15 m tall, but usually smaller, often thorny and gnarled; trunk irregularly fluted and contorted, attaining a length of 2—3 m and a diameter of 60 cm, although usually much less, prolonged into large, rather long and straight branches; bark grey to brown, rather smooth, peeling in flakes. Leaves alternate, paripinnate, distichous or fascicled on very short branches; stipules partly small and caducous, partly spine-like; leaflets in 2—4 pairs, obcordate or obovate, 10—35 mm x 5—25 mm, acute at base, emarginate at apex, closely veined and glabrous. Flowers in 5—20 cm long racemes in the axils of present or fallen leaves, 5-merous, sweet-scented; calyx 4—5 mm long, deeply lobed; petals 5—7 mm long, bright yellow; stamens 10, free; ovary superior, shortly stalked, glabrous; style filiform. Fruit a lanceolate, extremely flattened pod, 3—5 cm long, pointed at both ends, dehiscent not along the sutures but along the median of the sides, usually 2-seeded.

Logwood grows slowly, but cultivation is easy. With favourable growing conditions, the trees attain harvestable size in about 12 years. However, trees planted in the botanical garden at Bogor (Indonesia) in 1886 were only 2 m tall in 1918.

Haematoxylum L. ('bloodwood') is a small genus with about 4 species. It is indigenous to Central America and southern Africa. In Central America 2 species are usually distinguished, both producing a dye in the wood. Only Haematoxylum campechianum has spread over most of the tropics.
In Central America logwood trees which do not produce haematoxylin have been found. They are referred to as 'bastard logwood'.

Logwood is a lowland species which may grow under very different conditions. In Central America it grows best in flat marshy areas often inundated by rivers. In the West Indies, the best wood is produced in interior valleys and moist coves in the lower slopes of hills. In Jamaica, logwood is common on exposed limestone hillsides in dry secondary thickets. Logwood prefers light soils with some humus.

Logwood is propagated by seed or cuttings.

In Central America logwood is mostly collected from the wild where it occasionally forms almost pure stands.
The older the tree, the richer the colour of the wood because of oxidation of haematoxylin. In trade, however, wood with non-oxidized haematoxylin, thus young wood, is preferred. At harvest, the wood is cut into pieces 1—2.5 m long, and the sapwood is removed.

The pieces of wood are transported to the factory where they are mechanically reduced to small chips. The dye is extracted in boiling water, the resulting orange-red solution turns yellow and later black when cooled. After evaporation a powder remains.

No specific data are available on the genetic variability, but the wide variation in habitats and the existence of plants lacking haematoxylin suggest considerable variation within the species.

A more or less constant group of consumers appreciate logwood for its specific properties. The inadequacy of the alternatives has helped to maintain a reasonably good market outlook for the product. In fact, logwood is one of the few vegetable dyes with current importance on the world market. Although world demand is not expected to increase substantially, experiments on the cultivation of logwood in South-East Asia might be worthwhile.

Anand, N., 1983. The market for anatto and other natural colouring materials, with special reference to the United Kingdom. Tropical Development and Research Institute, Overseas Development Administration, London. pp. 17—19.
Echenique-Manrique, R. & del Amo, R.S., 1977. Palo de campeche (Haematoxylon campechianum L.). Inireb Informa. Communicado 17. Mexico. 3 pp.
Kochhar, S.L., 1981. Economic botany in the tropics. MacMillan India Ltd, Delhi, Bombay, Calcutta, Madras. pp. 380—381.
Sastri, B.N. (Editor), 1959. The wealth of India. Raw materials. Vol. 5. Council of Scientific and Industrial Research, New Delhi. pp. 2—3.

C.J.P. Seegeler

Seegeler, C.J.P., 1991. Haematoxylum campechianum 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