Zanha africana

Family

Sapindaceae

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Synonyms

Dialiopsis africana Radlk. (1907).

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Vernacular names

Velvet-fruited zanha (En). Mkalya, mkwanga (Sw).

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Origin and geographic distribution

Zanha africana is distributed from eastern DR Congo east to Kenya and south to southern Angola, Zimbabwe and Mozambique.

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Uses

The wood is locally used for construction, door frames, tool handles, implements and household articles and is of some value as firewood. It is suitable for flooring, mine props, ship building, vehicle bodies, furniture, toys, novelties, agricultural implements, railway sleepers and turnery.
It has been reported that fruits are eaten by humans, having a pleasant taste comparable to the taste of apricots (Prunus armeniaca L.), but seeds should not be swallowed as they are reputed to be poisonous and fruits are reported to cause severe diarrhoea if eaten in larger quantities. Various parts of Zanha africana contain saponins, especially the root bark, stem bark and fruits, and are used as a substitute for soap. They also act as a purgative, but can be dangerous if given to children. In Tanzania a root decoction is used to facilitate child birth, to treat constipation, prostate problems and fits. In Zimbabwe root infusions are taken as a cure for dysentery, but fatalities have been recorded. Powdered roots are rubbed on legs or are taken as an infusion to stop aching. Root preparations are prescribed to treat tooth-ache, rheumatic pains, pneumonia and vertigo. Half a teaspoon of dry powdered roots is put in cold water and drunk to prevent miscarriage, and to treat typhoid and fever. Root decoctions are drunk or sniffed to treat headache, convulsions and abdominal pain. Powdered root bark is added to tea or porridge to cure constipation, impotency and helminthiasis. Root bark extracts are used to treat fungal infections including ringworm of the head (Tinea capitis). The bark is used in the treatment of sexually transmitted diseases, hernia, convulsion, abdominal pain, headache, colds and fever. Pounded leaves added to water are taken or applied to the whole body to cure convulsion. Leaves are browsed by cattle, goats and sheep. In Tanzania Zanha africana is planted as a shade tree and is valued as nectar plant for honey bees.

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Production and international trade

Properties

The heartwood is pinkish to red-brown when freshly cut, turning pale brown to pinkish brown upon drying, and fairly distinctly demarcated from the yellowish white, 1–2 cm wide sapwood. Grain wavy to interlocked, texture fine.
The wood is fairly heavy with a density of 705–900 kg/m³ at 12% moisture content. It air dries moderately rapidly with slight distortion and no splitting. Boards of 2.5 cm thick dry to 12% moisture content in about 3 months, boards of 5 cm thick in 6 months. The rates of shrinkage are low, from green to 12% moisture content 2.7% radial and 4.5% tangential. At 12% moisture content, the modulus of rupture is 77 N/mm², modulus of elasticity 9310 N/mm², compression parallel to grain 46 N/mm², shear 14 N/mm² and Janka side hardness 6660 N.
The wood is difficult to saw because it is hard and has a tendency to gum saw teeth. Planing is also difficult because of the presence of interlocked grain causing picking up on quarter-sawn surfaces; a cutting angle of 15° is recommended. The wood shows satisfactory mortising, drilling, moulding and turning characteristics. Pre-boring is needed in nailing; the nail-holding power is good. The wood is durable, being quite resistant to termite, borer and Lyctus attacks. It is resistant to treatment with preservatives. The sawdust is irritant to mucous membranes and respiratory tracts.
The fresh fruit contains about 70% water. 100 g of dry matter of the fruit contains: energy 1265 kJ (303 kcal), protein 2 g, fat 1.5 g, fibre 15 g, Ca 90 mg, P 120 mg and Fe 20 mg. The fruits contain 10.5% acid saponin.
The presence of anthocyanins, coumarins, saponins, steroids, tannins and volatile oils has been established in the root bark. Zanhasaponin A, B and C were isolated from the roots, and these compounds showed topical anti-inflammatory activity. Antifungal activity of the root bark has been confirmed, but tests for antibacterial activity gave contradicting results. A dichloromethane extract of the roots showed trypanocidal activity with an IC₅₀ value of 12.6 μg/ml.

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Description

Deciduous, dioecious shrub or small tree up to 12(–17) m tall; bole branchless for up to 6 m, cylindrical, sometimes crooked, up to 100 cm in diameter; bark surface reddish to dark brown, scaling off in large flakes revealing an orange lower layer, inner bark reddish; crown open, with erect branches; twigs hairy when young. Leaves alternate, paripinnately compound with 3–6(–8) pairs of leaflets; stipules absent; petiole 1–5 cm long, rachis 4–34 cm long, reddish brown short-hairy; petiolules 1–3 mm long; leaflets opposite, ovate to elliptical or almost round, 8–15 cm × 4–8 cm, rounded to cordate at base, obtuse at apex, margin entire to slightly toothed towards the apex, reddish brown short-hairy below, pinnately veined with up to 14 pairs of lateral veins. Inflorescence a terminal or axillary panicle with flowers in dense clusters. Flowers unisexual, regular, small, greenish, sweet-scented; pedicel c. 2.5 mm long, hairy; sepals 4–6, c. 4 mm long, fused at base, hairy outside; petals absent; stamens 4–6, up to 10 mm long; disk cup-shaped; ovary superior, hairy, 2-celled, style c. 2 mm long; male flowers without ovary, female flowers with rudimentary stamens. Fruit an ellipsoid fleshy drupe up to 3 cm × 2 cm, velvety hairy, yellow to bright orange, 1-seeded. Seed ellipsoid, c. 1.5 cm × 1 cm.

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Other botanical information

Zanha comprises 3 species. The distribution of Zanha golungensis Hiern, another timber tree, overlaps with that of Zanha africana, but it has a wider distribution, westwards as far as Senegal.
Zanha suaveolens Capuron, endemic to Madagascar, is a small tree up to 15 m tall with a bole diameter of up to 60 cm. Its wood is used in boat building. The bark is used as a soap substitute; it is used especially for delicate textiles such as silk.

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Anatomy

Wood-anatomical description (IAWA hardwood codes):
Growth rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; 13: simple perforation plates; 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 25: intervessel pits small (4–7 μm); 26: intervessel pits medium (7–10 μm); 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 41: mean tangential diameter of vessel lumina 50–100 μm; 48: 20–40 vessels per square millimetre; 58: gums and other deposits in heartwood vessels. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 70: fibres very thick-walled. Axial parenchyma: 80: axial parenchyma aliform; 82: axial parenchyma winged-aliform; 83: axial parenchyma confluent; (85: axial parenchyma bands more than three cells wide); (86: axial parenchyma in narrow bands or lines up to three cells wide); 91: two cells per parenchyma strand; 92: four (3–4) cells per parenchyma strand. Rays: 96: rays exclusively uniseriate; (97: ray width 1–3 cells); 104: all ray cells procumbent; 115: 4–12 rays per mm. Mineral inclusions: 136: prismatic crystals present; 142: prismatic crystals in chambered axial parenchyma cells.
(S. N’Danikou, P.E. Gasson & H. Beeckman)

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Growth and development

In southern Africa the tree sheds most of its leaves during the dry season. The flowers appear before the new leaves between October and December. Fruits mature between November and February. They are eaten by birds, chimpanzees and monkeys, which probably disperse the seeds.

Ecology

Zanha africana is found in open woodland, often on granite ridges or kopjes, and occasionally in riverine forest, at 600–1550 m altitude.

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Propagation and planting

Zanha africana is easiest propagated with fresh seeds. Propagation with cuttings is also practised.

Management

Although Zanha africana is the second most important medicinal tree in the Shinyanga Region in Tanzania, only few people grow the tree at their homesteads. It is more common to grow the species in farmland, but most people still harvest plant parts when needed from the natural forest.

Genetic resources and breeding

There are no indications that Zanha africana is threatened or vulnerable. Its timber is not widely used and it does not produce good firewood. Moreover, the presence of poisonous saponins may discourage people from using it. Zanha africana is not a protected species in Africa.

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Prospects

Zanha africana produces timber of little commercial value because it is often only available in small dimensions due to the small size of the bole and because the sawing and working characteristics of the wood are poor. However, it will remain an important source of wood for local uses where durability is important, especially in construction. There is very little or no information on its propagation and management. Therefore, research is needed to explore methods of propagation, planting and managing this multipurpose species.

Major references

• Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
• Bryce, J.M., 1967. The commercial timbers of Tanzania. Tanzania Forest Division, Utilisation Section, Moshi, Tanzania. 139 pp.
• Coates Palgrave, K., 2002. Trees of southern Africa. 3rd Edition. Struik Publishers, Cape Town, South Africa. 1212 pp.
• Davies, F.G. & Verdcourt, B., 1998. Sapindaceae. In: Beentje, H.J. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 108 pp.
• Dery, B.B., Otsyina, R. & Ng'atigwa, C. (Editors), 1999. Indigenous knowledge of medicinal trees and setting priorities for their domestication in Shinyanga Region, Tanzania. ICRAF, Nairobi, Kenya. 98 pp.
• Exell, A.W., 1966. Sapindaceae. In: Exell, A.W., Fernandes, A. & Wild, H. (Editors). Flora Zambesiaca. Volume 2, part 2. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 494–543.
• Storrs, A.E.G., 1979. Know your trees: some of the common trees found in Zambia. Forest Department, Ndola, Zambia. 380 pp.
• van Wyk, B. & van Wyk, P., 1997. Field guide to trees of southern Africa. Struik Publishers, Cape Town, South Africa. 536 pp.

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Other references

• Abbot, P.G. & Lowore, J.D., 1995. Livestock grazing in Chimaliro Forest Reserve: preliminary results and implications for the management of browse. Forestry Research Institute, Zomba, Malawi. 25 pp.
• Arbonnier, M., 2000. Arbres, arbustes et lianes des zones sèches d’Afrique de l’Ouest. CIRAD, MNHN, UICN. 541 pp.
• Boiteau, P., Boiteau, M. & Allorge-Boiteau, L., 1999. Dictionnaire des noms malgaches de végétaux. 4 Volumes + Index des noms scientifiques avec leurs équivalents malgaches. Editions Alzieu, Grenoble, France.
• Chhabra, S.C., Mahunnah, R.L.A. & Mshiu, E.N., 1991. Plants used in traditional medicine in eastern Tanzania. 5. Angiosperms (Passifloraceae to Sapindaceae). Journal of Ethnopharmacology 33: 143–157.
• Cuéllar, M.J., Giner, R.M., Recio, M.C., Just, M.J., Máñez, S., Cerdá, M., Hostettmann, K. & Ríos, J.L., 1997. Zanhasaponins A and B, antiphospholipase A2 saponins from an antiinflammatory extract of Zanha africana root bark. Journal of Natural Products 60(11): 1158–1160.
• Cuéllar, M.J., Giner, R.M., Recio, M.C., Just, M.J., Máñez, S., Ríos, J.L., Bilia, A.R., Msonthi, J. & Hostettmann, K., 1997. Three new oleanane saponins from Zanha africana. Journal of Natural Products 60(2): 191–194.
• Fabry, W., Okemo, P. & Ansorg, R., 1996. Fungistatic and fungicidal activity of east African medicinal plants. Mycoses 39(1-2): 67–70.
• Gelfand, M., Mavi, S., Drummond, R.B. & Ndemera, B., 1985. The traditional medical practitioner in Zimbabwe: his principles of practice and pharmacopoeia. Mambo Press, Gweru, Zimbabwe. 411 pp.
• Kambizi, L. & Afolayan, A.J., 2001. An ethnobotanical study of plants used for the treatment of sexually transmitted diseases (njovhera) in Guruve District, Zimbabwe. Journal of Ethnopharmacology 77: 5–9.
• Kareru, P.G., Kenji, G.M., Gachanja, A.N, Keriko, J.M. & Mungai, G., 2007. Traditional medicines among the Embu and Mbeere peoples of Kenya. African Journal of Traditional, Complementary and Alternative Medicines 4(1): 75–86.
• Malaisse, F., 1997. Se nourir en fôret claire africaine. Approche écologique et nutritionelle. Les presses agronomiques de Gembloux, Gembloux, Belgium & CTA, Wageningen, Netherlands. 384 pp.
• Musila, W., Kisangau, D. & Muema, J., 2004. Conservation status and use of medicinal plants by traditional medical practitioners in Machakos District, Kenya. [Internet] http://www.ed.psu.edu/ icik/ 2004Proceedings/section3-musila-kisangau-muema-withpics.pdf Accessed May 2010.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Nibret, E., Ashour, M.L., Rubanza, C.D. & Wink, M., 2010. Screening of some Tanzanian medicinal plants for their trypanocidal and cytotoxic activities. Phytotherapy Research 24(6): 945–947.
• Ruffo, C.K., Birnie, A. & Tengnäs, B., 2002. Edible wild plants of Tanzania. Technical Handbook No 27. Regional Land Management Unit/ SIDA, Nairobi, Kenya. 766 pp.
• Schatz, G.E., 2001. Generic tree flora of Madagascar. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 477 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.

Afriref references

Sources of illustration

• Coates Palgrave, K., 2002. Trees of southern Africa. 3rd Edition. Struik Publishers, Cape Town, South Africa. 1212 pp.
• Exell, A.W., 1966. Sapindaceae. In: Exell, A.W., Fernandes, A. & Wild, H. (Editors). Flora Zambesiaca. Volume 2, part 2. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 494–543.

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Author(s)

•	W. Mojeremane Department of Crop Science and Production, Botswana College of Agriculture, Private Bag 0027, Gaborone, Botswana

Editors

•	R.H.M.J. Lemmens PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
•	D. Louppe CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
•	A.A. Oteng-Amoako Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Associate editors

•	E.A. Obeng Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Photo editor

•	G.H. Schmelzer PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Mojeremane, W., 2011. Zanha africana (Radlk.) Exell. [Internet] Record from PROTA4U. Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>. Accessed .

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