Prota 3: Dyes and tannins/Colorants et tanins
Trans. Linn. Soc., ser. 2, Bot. 1: 264 (1878).
Zebra leaf aloe, spotted aloe (En). Aloès zébré, aloès tacheté (Fr).
Origin and geographic distribution
Aloe zebrina is widespread in southern Africa, from Angola, through Namibia, Botswana and Zimbabwe to Mozambique.
Particularly in north-western Botswana (Ngamiland), but also elsewhere in its distribution area, the roots of Aloe zebrina are among the main dyes for the Hyphaene palm fibres used in basketry weaving to which they give a golden-yellow colour. They have been adopted for wool dyeing by European settlers who introduced the use of metallic mordants such as alum to obtain more intense, fast colours. Other uses include the making of cakes with the boiled and pressed flowers among the people along the Kunene river in Angola. Medicinally, a decoction of the powdered stem and leaf bases is taken orally twice a day by women after delivery to cleanse the system. The (bitter) juice of many Aloe species is used as a powerful purgative and worm expellant, as disinfectant for wounds, and to treat skin problems including conjunctivitis. Like many Aloe species Aloe zebrina has ornamental value and potential for cultivation in arid to semi-arid, frost-free locations. Seed is readily available from specialist suppliers.
The yellow leaf sap of most Aloe species contains anthrone C-glycosides such as aloin and homonataloin, and the yellow root sap anthranoid aglycones such as chrysophanol (a fast orange-brown colorant) and asphodeline. The roots of Aloe zebrina (and Aloe parvibracteata Schönl.) further contain aloesaponarin, aloesaponol and related compounds of the 1-methyl-8-hydroxyanthraquinone pathway. Moreover, isoleutherol is a unique chemical compound found in the roots of spotted aloes.
Succulent herb up to 160 cm tall, without stem or with a short stem up to 30 cm long, freely suckering and forming dense groups, with yellowish leaf sap. Leaves 15–25, densely clustered into a rosette, without petiole, linear-lanceolate, 15–30 cm × 6–7 cm, fleshy, upper surface rather flat, powdery-glaucous, striate and marked with large oblong whitish spots more or less arranged in a series of irregular transverse bands, lower surface convex, very powdery-glaucous, margins armed with stout, horny, deltoid, brown-tipped teeth 6–7 mm long, 10–16 mm distant. Inflorescence with stalk copiously branched above the middle, the branches terminating in lax racemes 30–40 cm long; bracts linear-lanceolate, c. 1 cm long. Flowers bisexual, regular; pedicel 6–7 mm long; perianth tubular, 3–3.5 cm long, 6-lobed, dull red, much inflated around the ovary, 3 outer lobes acute, many-veined, 3 inner lobes more obtuse and wider; stamens 6, included; ovary superior, 6-grooved, 3-celled, style filiform, stigma headlike. Fruit a capsule, dehiscing loculicidally, many-seeded. Seeds c. 7 mm long, broadly winged, dark coloured, punctate.
Aloe comprises about 330 species, of which about 275 occur in mainland Africa, 40 in Madagascar and 15 in Arabia. Aloe zebrina is variable. In its natural distribution area it flowers mostly between February and April, some types in June–July.
The group of aloes to which Aloe zebrina belongs (called spotted or maculate aloes) is characterized by relatively small, usually stemless rosettes, spotted leaves and swollen flower bases. Since the species within this group are very similar it seems likely that the roots of almost all of them are suitable as a source of dye. Examples are Aloe cryptopoda Baker, found in Malawi, Botswana, Zimbabwe, Mozambique and South Africa, the roots of which dye wool red-brown to purplish-red, depending on the mordant; Aloe marlothii A.Berger, found in Botswana, Mozambique, South Africa and Swaziland, the roots of which dye yellow; and Aloe parvibracteata Schönl., found in Mozambique, South Africa and Swaziland, the roots of which dye yellow. The leaves of several less closely related Aloe species can also be used for dyeing, e.g. those of the South African species Aloe speciosa Baker give a beautiful delicate pink colour to wool, even without mordants, and those of Aloe succotrina All. shades of reddish-purple. Several species growing in Ethiopia (e.g. Aloe steudneri Schweinf., Aloe percrassa Tod.) give red dyes.
Aloe zebrina is found in dry thickets and marshy meadows on river banks.
Aloe zebrina suckers freely and can form dense groups, although differences exist between populations. Its roots can easily be collected on a sustainable basis because the plants easily form new roots, provided they are left to grow again. For dyeing Hyphaene palm fibres, the roots are collected from the wild, preferably on a small scale, and boiled with the weaving material until a golden-yellow colour is obtained. In Ethiopia, the leaves of Aloe sp. (‘sete ret’) are chopped and boiled in water with white cloth until it is dyed red.
Genetic resources and breeding
Aloe zebrina is quite widespread in southern Africa, but is, like all Aloe species, protected against collection and trade from the wild by CITES regulations. In South Africa several germplasm collections are available in botanical gardens.
Aloe zebrina will remain only locally important as a dye plant. The ornamental value of all aloes will remain of major economic importance.
• Reynolds, G.W., 1982. The Aloes of South Africa. 4th edition. A.A. Balkema, Rotterdam, Netherlands. 538 pp.
• Tournerie, P.J.M., 1986. Colour and dye recipes of Ethiopia. Published by the author, Exeter, United Kingdom. 152 pp.
• Schweppe, H., 1993. Handbuch der Naturfarbstoffe, Vorkommen, Verwendung, Nachweis. Ecomed, Landsberg/Lecj, Germany. 800 pp.
• van Wyk, B.E. & Gericke, N., 2000. People’s plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria, South Africa. 351 pp.
• Watt, J.M. & Breyer-Brandwijk, M.G., 1962. The medicinal and poisonous plants of southern and eastern Africa. 2nd Edition. E. and S. Livingstone, London, United Kingdom. 1457 pp.
Correct citation of this article:
Jansen, P.C.M., 2005. Aloe zebrina Baker In: Jansen, P.C.M. & Cardon, D. (Editors). PROTA 3: Dyes and tannins/Colorants et tanins. [CD-Rom]. PROTA, Wageningen, Netherlands.