Neoboutonia macrocalyx (PROTA)

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Plant Resources of Tropical Africa
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Neoboutonia macrocalyx Pax


Protologue: Bot. Jahrb. Syst. 30: 339 (1901).
Family: Euphorbiaceae

Origin and geographic distribution

Neoboutonia macrocalyx is distributed from eastern DR Congo eastward to Kenya and southward to Zimbabwe and Mozambique.

Uses

In East Africa the wood of Neoboutonia macrocalyx is used in house construction and for carving and inner parts of plywood. In Tanzania it is further used for boxes, crates, stools, water pots and beehives. The wood is a good substitute for balsa wood (from Ochroma pyramidale (Cav. ex Lam.) Urb.). It is widely used as firewood.

In Uganda Neoboutonia macrocalyx has been planted for soil conservation. In East Africa root infusions and root scrapings are taken as purgative, root decoctions to treat diabetes, leaf infusions as emetic and leaf decoctions against dizziness, whereas a decoction of leaves and twig bark is drunk and used as a wash to cure fever.

Properties

The heartwood is white to grey-white, often with irregular dark brown streaks, and not distinctly demarcated from the sapwood. The grain is straight, texture coarse.

The wood is lightweight, with a density of 350–390 kg/m³ at 12% moisture content. It air and kiln dries rapidly. The wood is easy to saw and work with sharp hand and machine tools. It usually planes to a woolly or stringy finish, with lustrous surfaces. The nailing, screwing, gluing, varnishing, painting and jointing properties are all satisfactory. The wood has good steam bending properties. It has a low durability, being liable to fungal attacks including blue stain, termite, pinhole borer and marine borer attacks. The heartwood is moderately permeable to preservatives, the sapwood permeable. The wood is said to be suitable for paper pulp.

Bark extracts of Neoboutonia macrocalyx have shown antiplasmodial activity, and 4 different tigliane-type diterpenoids have been isolated from these extracts. These compounds are known to have biological properties such as irritant, cytotoxic, carcinogenic and antitumor activity, and may be responsible for the antiplasmodial activity of the extracts.

Description

Dioecious, small to medium-sized tree up to 20(–40) m tall; bole straight and cylindrical, up to 60 cm in diameter; bark surface smooth, pale white to grey; crown spreading; twigs densely stellate hairy. Leaves alternate, simple and usually entire; stipules ovate, up to 1 cm long; petiole 5–15 cm long, densely stellate hairy; blade broadly ovate to nearly orbicular, 10–30 cm × 10–15 cm, deeply cordate at base, short-acuminate at apex, stellate hairy on the veins and minutely gland-dotted below, with 7–9 veins from the base and 5–7 pairs of lateral veins. Inflorescence a terminal panicle up to 30 cm long, often leafy at base. Flowers unisexual, regular, without petals; male flowers with 2–3 mm long pedicel, calyx cream-coloured, with 2–3 broadly ovate lobes 2.5–3 mm long, disk glands 10, stamens 30–40, free, up to 3 mm long; female flowers with pedicel up to 8 mm long, calyx with 4–6 lobes c. 3 mm long but accrescent in fruit, disk shallowly 5-lobed, ovary superior, 3-lobed, c. 2 mm in diameter, densely stellate hairy, styles c. 2 mm long. Fruit a 3-lobed capsule c. 1 cm in diameter, stellate hairy, 3-seeded. Seeds ellipsoid, c. 7 mm × 5 mm, dark brown-mottled.

Other botanical information

Neoboutonia comprises only 3 species and is restricted to mainland tropical Africa. The 2 other species, Neoboutonia mannii Benth. (synonyms: Neoboutonia diaguissensis Beille, Neoboutonia glabrescens Prain) and Neoboutonia melleri (Müll.Arg.) Prain have a wider distribution than Neoboutonia macrocalyx. They are doubtfully distinct as differences are minor. Both are usually multi-stemmed small trees up to 12(–20) m tall, with a combined distribution area from Guinea eastward to southern Sudan and Uganda, and southward to Zambia, Angola and Mozambique. In West Africa the wood is sawn into planks, and in DR Congo it is used for construction and as firewood. In Tanzania the wood is used in the same way as that of Neoboutonia macrocalyx. In Congo and DR Congo root and bark decoctions are taken as purgative and anthelmintic. They have abortifacient properties and therefore are not given to pregnant women. In eastern DR Congo roots are chewed as a cure for gonnorhoea. In Cameroon the baked pulverized bark is eaten once a week to prevent epileptic fits. This treatment causes diarrhoea and vomiting, and high doses can be fatal. The bark has skin-irritant properties and is used in Cameroon against worms, abdominal pains, stomach-ache and malaria.

Ecology

Neoboutonia macrocalyx is found mainly in lower montane forest in high rainfall areas at 600–2500 m altitude, as a pioneer in clearings and along streams. Secondary forests can consist of almost pure stands.

Management

Propagation of Neoboutonia macrocalyx is easily done with seedlings or wildlings. Fruits should be collected just before they open. After they have opened and the seeds are dry, these can be stored in a sealed container in a cool place. For good results seeds should be used within 2 months after harvesting. The growth is fast and trees can be pollarded or coppiced. Usually Neoboutonia macrocalyx is grown in pure stands for production of firewood or in lines or strips for soil conservation.

Genetic resources

There are no serious threats because Neoboutonia macrocalyx is a widespread pioneer which is abundant in secondary forest.

Prospects

Neoboutonia macrocalyx may not be a first-choice timber tree, but may have potential for paper production, soil conservation and firewood production.

Major references

  • Chikamai, B.N., Githiomi, J.K., Gachathi, F.N. & Njenga, M.G., undated. Commercial timber resources of Kenya. Kenya Forestry Research Institute (KEFRI), Nairobi, Kenya. 164 pp.
  • Katende, A.B., Birnie, A. & Tengnäs, B., 1995. Useful trees and shrubs for Uganda: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 10. Regional Soil Conservation Unit, Nairobi, Kenya. 710 pp.
  • Kirira, P.G., Rukunga, G.M., Wanyonyi, A.W., Muthaura, C.N., Mungai, G.M., Machocho, A.K. & Ndiege, I.O., 2007. Tigliane diterpenoids from the stem bark of Neoboutonia macrocalyx. Journal of Natural Products 70(5): 842–845.
  • Lovett, J.C., Ruffo, C.K., Gereau, R.E. & Taplin, J.R.D., 2007. Field Guide to the moist forest trees of Tanzania. Frontier Publishing, United Kingdom. 303 pp.
  • Radcliffe-Smith, A., 1996. Euphorbiaceae, subfamilies Phyllantoideae, Oldfieldioideae, Acalyphoideae, Crotonoideae and Euphorbioideae, tribe Hippomaneae. In: Pope, G.V. (Editor). Flora Zambesiaca. Volume 9, part 4. Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 1–337.

Other references

  • Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
  • 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.
  • Burkill, H.M., 1994. The useful plants of West Tropical Africa. 2nd Edition. Volume 2, Families E–I. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 636 pp.
  • Chifundera, K., 2001. Contribution to the inventory of medicinal plants from the Bushi area, South Kivu Province, Democratic Republic of Congo. Fitoterapia 72: 351–368.
  • Dale, I.R. & Greenway, P.J., 1961. Kenya trees and shrubs. Buchanan’s Kenya Estates Limited, Nairobi, Kenya. 654 pp.
  • Kirira, P.G., Rukunga, G.M., Wanyonyi, A.W., Muregi, F.M., Gathirwa, J.W., Muthaura, C.N., Omar, S.A., Tolo, F., Mungai, G.M. & Ndiege, I.O., 2006. Anti-plasmodial activity and toxicity of extracts of plants used in traditional malaria therapy in Meru and Kilifi districts of Kenya. Journal of Ethnopharmacology 106: 403–407.
  • Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
  • Tene, M., Tane, P., Tamokou, J., Kuiate, J.-R., Connolly, J.D., 2008. Degraded diterpenoids from the stem bark of Neoboutonia mannii. Phytochemistry Letters 1(2): 120–124.
  • Yamada, T., 1999. A report of the ethnobotany of the Nyindu in the eastern part of the former Zaire. African Study Monographs 20(1): 1–72.
  • Zhao, W., Wolfender, J.-L., Mavi, S. & Hostettmann, K., 1998. Diterpenes and sterols from Neoboutonia melleri. Phytochemistry 48(7): 1173–1177.

Author(s)

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

Correct citation of this article

Bosch, C.H., 2012. Neoboutonia macrocalyx Pax. In: 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. Accessed 7 March 2020.