Prota 3: Dyes and tannins/Colorants et tanins
Prodr. 3: 21 (1828).
2n = 26
Combretum passargei Engl. & Diels (1899), Combretum relictum (Aubrév.) Hutch. & Dalziel (1927).
Bois d’éléphant, chigommier (Fr).
Origin and geographic distribution
Combretum glutinosum is widespread all over West Africa and extends to Sudan.
In West Africa, particularly from Senegal to Côte d’Ivoire, the leaves, stems and root bark of Combretum glutinosum, collected from the wild, are important sources of yellow to brownish yellow dyes for cotton textiles. In Burkina Faso, Benin and Nigeria, these dyes are also used to dye leather and mats made of various vegetable fibres. The main importance of Combretum glutinosum (called ‘càngàra bilen’ in Bamanankan, Mali) however, is in the preparation of the internationally renowned ‘bogolanfini’ or ‘bogolan’ textiles (‘mudcloth’) of Mali, where other tannin-rich plants are also used, depending on the local resources and traditions. Combretum glutinosum is much used in the Bélédougou region, north of Bamako. The black designs of bogolan are obtained by the reaction of plant tannins with iron salts contained in local fermented mud. While the basic process of making black dyes with tannin-plants and mordanting with iron-rich mud has been known all over the world and is still very much used in other parts of Africa for barkcloth and vegetable fibres, the special art of bogolan originally belongs to the women of several peoples of the Mande group: Bamanan, Dogon, Malinke, Minianka, Bobo and Senoufo. Formerly it was used to decorate garments for special groups of people and special occasions, imparting them symbolic protective and curative powers, but recently these cloths have attracted the attention of the international fashion world. Malian artists and fashion designers have adapted techniques and designs, generating an increasing worldwide demand.
Combretum glutinosum is also used in indigo dyeing; from Senegal to Nigeria, the wood ash is particularly appreciated to maintain the indigo vat at the optimum alkaline pH.
The fresh young leaves, though bitter-tasting, are occasionally eaten as a vegetable, in Senegal together with taro (Colocasia esculenta (L.) Schott), and furnish a useful forage relished by all stock in the Sahel zone. The wood is yellowish, hard and very durable and is used in house construction, for tool handles and as firewood. In Nigeria smoke of the wood is used for fumigation and as an incense. In traditional medicine Combretum glutinosum is highly valued. A decoction or infusion of the leaves, bark or fruits is very popular, mainly to treat urinary, liver and kidney complaints, but also all kinds of respiratory problems, fevers, intestinal complaints and to clean wounds and sores. Crushed or dry powdered leaves or bark are used as a dressing on wounds. The Maninka people take a leaf decoction in baths and by draught against general fatigue. In Senegal the gum of the bark is used to fill the cavity of a carious tooth. Young shoots and roots are believed to have aphrodisiac properties.
Production and international trade
The increased interest and demand has made bogolan production an important economic activity with centres spreading from Mali to neighbouring countries, and with international markets, mostly in Europe and the United States. Wood ash from Combretum glutinosum, widely used in indigo dyeing, is traded for this use both at regional and international scale but statistics are not available.
Gallic acid, ellagic acid, flavonoid glycosides and 4 tannins have been isolated from the leaves of Combretum glutinosum. The tannins are 2,3-(S)-hexahydroxydiphenoyl- D-glucose, punicalin, punicalagin and combreglutinin. The bogolan process is based on the reaction of the tannins with the soluble iron compounds present in the fermented mud, resulting in a black colour. In traditional bogolan, mud is applied everywhere, leaving only the fine lines of the designs mud-free resulting in a yellowish design on a black ground. The yellow colour imparted to the cotton cloth by the mixture of flavonoids and tannins present in the dye bath is later bleached, which was achieved formerly by an application of home-made soap using ash-lye, and is mostly done now with commercial bleaching agents.
Gum, present in the bark, consists of uronic acid compounds which hydrolyze to a number of sugars. Combreglutinin has interesting medicinal properties, particularly for the treatment of hepatitis B. Other proven medicinal effects of Combretum glutinosum are promoting discharge of urine, reduction of hypertension, discharge of bladder stone and antitussive and disinfectant properties of the leaves.
Adulterations and substitutes
In the bogolan process, the leaves of Combretum glutinosum can be replaced by those of the more often used Anogeissus leiocarpa (DC.) Guill. & Perr. which have similar effects, giving yellow dyes that can be bleached easily to leave white designs on a black ground. The barks of Lannea microcarpa Engl. & K.Krause and Terminalia macroptera Guill. & Perr. are also used to dye bogolan textiles, but the ochre to reddish colours obtained are preserved, not bleached, giving textiles with reddish designs on a black ground or a reddish ground with black designs, the black colour being due in all cases to the reaction of the various tannins present in the plants with the iron compounds of the mud.
Shrub or small tree up to 12 m tall; bole up to 60 cm in diameter, often crooked or branched from the base; bark rough and grooved, grey; crown rounded and open; branches densely and shortly greyish hairy. Leaves opposite to slightly alternate or sometimes in whorls of 3–4, simple; stipules absent; petiole 0.5–1.5(–3.5) cm long; blade elliptical, ovate or obovate, 9–18(–35) cm × 4–8(–20) cm, base rounded to attenuate, apex rounded to acute, margin entire, sometimes wavy, when young usually sticky above and densely grey pubescent below, lateral veins prominent, in 7–15 pairs. Inflorescence an axillary spike, up to 6 cm long. Flowers bisexual, regular, 4-merous, yellowish green, fragrant, sessile; receptacle cup-shaped, up to 4 mm wide; calyx lobes triangular; petals free, obovate to circular, 1–2.5 mm long; stamens 8; ovary inferior, style exserted. Fruit an ellipsoid, 4-winged samara 2.5–4 cm × 1.5–3 cm, glabrous or pubescent, often sticky near the centre, red to yellow-brown.
Other botanical information
Combretum is a very large genus, comprising about 250 species and distributed worldwide in the tropics and subtropics. About 140 species occur in tropical Africa. Combretum schweinfurthii Engl. & Diels, known from DR Congo, Sudan and Uganda, is possibly synonymous with Combretum glutinosum.
Several other Combretum species are used for dyeing in Africa. The major ones are: Combretum erythrophyllum (Burch.) Sond. from southern Africa of which the roots are used to dye textiles and baskets into rich dark brown colours, but its major use is as timber; Combretum micranthum G.Don from the western Sahel, used to dye red colours but more important as a medicinal plant; Combretum nigricans Lepr. ex Guill. & Perr. occurring from Senegal to Sudan and used to dye orange-red colours, but more important for its gum; Combretum paniculatum Vent., which is widespread all over tropical Africa and yields a yellow dye used in Kenya to dye green in combination with blue dyes, but more important as a medicinal plant.
Growth and development
In the savanna zone Combretum glutinosum is evergreen, in the Sahel it loses its leaves for a few months during the dry season. Flowering is in the dry season after bush fires to which it is very resistant. Once established in an area, it easily forms dense stands.
Combretum glutinosum is found in savanna and open woodland with an annual rainfall of 200–900 mm. It is particularly resistant to arid conditions, surviving where grasses will not, and it recovers quickly from burning. It often grows gregariously on sandy and degraded soils.
Combretum glutinosum is not cultivated but often conserved when land is cleared. The tree coppices well. It is often infected by Loranthaceae plant parasites.
The parts used for dyeing (leaves, bark, wood) are collected from shrubs and trees growing in the wild. In the Bélédougou region, fresh leaves collected just after the rainy season (in October) are considered best. Boys climb the trees and cut the ends of the young branches which are then tied together in bundles. These can be used fresh or are dried and stored for later use.
Handling after harvest
According to traditional Mandé recipes, the fresh or dried leaves are boiled for about one hour in water to obtain a yellow liquid. The cloth is immersed in the bath when the liquid has cooled down. Then the cloth is dried in the sun and immersed in the bath again and this process is repeated several times until the desired basic yellow colour is obtained. While drying, the same side of the cloth is always exposed to the sun and turns a deeper yellow as a result of oxidation. When the cloth has been dyed and dried, it is stretched tautly and the parts that are planned to be dyed black are covered with liquid mud using a wooden stick (‘kala’) for straight lines and a special metal spatula (‘binyèni’) for drawing curves and filling spaces. When the mud is dry, it is shaken off and the cloth is washed well in water. The whole process of dyeing and applying mud is repeated up to 3 times to obtain a deep black ground. Finally the light-coloured designs are carefully covered with a bleaching paste. Sometimes the dye bath is prepared not by boiling, but by soaking fresh, previously pounded leaves for one or two days. This process takes longer, but saves fuel. The stem and root barks can also be pounded and steeped in water without heating to obtain orange shades for other types of textiles, in which case wood ash is usually added to the bath as a mordant.
Combretum glutinosum is widespread and not in danger of genetic erosion although the growing demand for bogolan textiles in recent years, plus other uses, are locally making the tree less common. Already in the 1990s women were complaining they had to walk ever further to gather the branches.
Combretum glutinosum will remain very important as a dye source in bogolan production. Growing interest in bogolan textiles will result in demand for greater and regular supplies of all the dye plants traditionally used. Taking also into account the demand due to the important medicinal properties of Combretum glutinosum, cultivation is recommended in the regions where it is used in big quantities, to prevent overexploitation and exhaustion of wild populations.
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Correct citation of this article:
Marquet, M. & Jansen, P.C.M., 2005. Combretum glutinosum Perr. ex DC. In: Jansen, P.C.M. & Cardon, D. (Editors). PROTA 3: Dyes and tannins/Colorants et tanins. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, flowering twig; 2, flower; 3, fruiting twig
Redrawn and adapted by Achmad Satiri Nurhaman
fruiting tree habit