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Mitragyna stipulosa (DC.) Kuntze

Protologue
Revis. gen. pl. 1: 289 (1891).
Family
Rubiaceae
Synonyms
Hallea stipulosa (DC.) J.-F.Leroy (1975), Fleroya stipulosa (DC.) Y.F.Deng (2007).
Vernacular names
African linden (En). Tilleul d’Afrique (Fr).
Origin and geographic distribution
Mitragyna stipulosa is widespread, from Senegal east to Uganda, and south to Zambia and Angola.
Uses
The wood, often traded as ‘abura’ or ‘bahia’, is used for light construction, flooring, interior joinery, interior trim, furniture, vehicle bodies, sporting goods, toys, novelties, transmission poles, canoes, drums, oars, tool handles, mortars, pestles, matches, carving, turnery, draining boards and particle board. It is also suitable for battery separators, veneer and plywood. The wood is recommended for paper making. It is also used as firewood and for charcoal production.
The bark has several uses in traditional medicine. Bark decoctions and macerations are taken to treat fever, vomiting, general weakness, hypertension, dysentery, gonorrhoea, amenorrhoea, leprosy, ulcers, colds, chest pain, stomach-ache, convulsions, food poisoning and sterility, to ease childbirth, and as anthelmintic and diuretic. Bark decoctions are added to a bath to treat rheumatism and haemorrhoids, and bark powder is applied to skin complaints. Leaves are applied to wounds and used to treat fever; they are also used to treat poisoning in cattle. Boiled roots are taken to treat colic. The leaves are used for thatching and for wrapping kola nuts.
Production and international trade
The wood of Mitragyna stipulosa is considered a first class wood of general utility. In trade it is not distinguished from Mitragyna ledermannii (K.Krause) Ridsdale wood and together they are sold under the name ‘abura’ or ‘bahia’. In Gabon the volume of Mitragyna logs exported increased from 10,000 m³ in 1982 to 25,000 m³ in 1991, and to 45,000 m³ in 1999. In 1999 ‘bahia’ ranked as fifth most important timber in Gabon, but probably the major part consists of Mitragyna ledermannii. In 2004 the export of ‘bahia’ sawn wood from Congo was 3000 m³ at an average price of US$ 165/m³; small amounts of veneer were also exported at an average price of US$ 177/m³. In 2005 Côte d’Ivoire exported 14,000 m³ of sawn wood at an average price of US$ 439/m³.
Properties
The heartwood is pale brown to pinkish brown or yellowish brown, slightly darkening upon exposure, and indistinctly demarcated from the wide sapwood. The grain is straight to interlocked, texture fine and even. The wood is slightly glossy on quarter-sawn surfaces, and has an unpleasant odour when freshly cut.
The wood is medium-weight with a density of 480–610 kg/m³ at 12% moisture content. It air and kiln dries rapidly, with slight risk of distortion and checking. The rates of shrinkage are moderately high, from green to oven dry 4.1–5.0% radial and 8.4–10.5% tangential. Once dry, the wood is moderately stable in service.
At 12% moisture content, the modulus of rupture is 65–117 N/mm², modulus of elasticity 9600–12,350 N/mm², compression parallel to grain 33–51 N/mm², shear 8–9 N/mm², cleavage 14–19 N/mm, Janka side hardness 3200–3430 N, Janka end hardness 4700–5200 N and Chalais-Meudon side hardness 1.9–2.6.
The wood works easily with hand and machine tools, but occasionally it has a rather high blunting effect on saw teeth and cutting edges because of the presence of silica; the use of stellite-tipped saw teeth and tungsten-carbide cutting edges is then recommended. The wood surface takes a high polish and finishes well. The nailing and screwing properties are good. Gluing is not problematic, but steam bending properties are poor. After steaming for 72 hours at 75°C, veneer of all thicknesses can be produced by peeling with satisfactory results, although the surface shows a tendency to become slightly fibrous. The veneer can be dried with only little splitting. The wood is resistant to acids and corrosion. It is not durable, being susceptible to termite, dry-wood borer and pinhole borer attacks. Fresh wood is susceptible to blue stain attack. The sapwood is easy to treat with preservatives, the heartwood moderately easy. Sawdust may be irritant and cases of nausea, eye irritation and dizziness have been recorded. The wood has a cellulose content of about 52% and an average fibre length of 1.6 mm, and makes a pale brown paper of satisfactory strength and quality.
Several alkaloids have been isolated from Mitragyna stipulosa. Some of these showed hypotensive, anaesthetic and intestinal and uterine contractive properties. Leaf and bark extracts of Mitragyna stipulosa showed antibacterial activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa, supporting the use in traditional medicine as antiseptic to treat wounds.
Triterpenoids have been isolated from the bark, including quinovic acid and associated glycoside derivatives. These compounds showed significant inhibitory activity against snake venom phosphodiesterase I.
Description
Evergreen medium-sized to fairly large tree up to 35(–40) m tall; bole straight and cylindrical or crooked, up to 95 cm in diameter, with low rounded buttresses or without buttresses; bark surface smooth to irregularly thin-scaly or longitudinally fissured, greyish brown to dark brown, inner bark finely fibrous, pale brown to pinkish brown, rapidly turning brownish upon exposure; crown rounded, with few, heavy branches; twigs angular, glabrous or slightly hairy. Leaves opposite, simple; stipules obovate to nearly round, up to 8 cm × 5 cm, hairy in lower part, with many parallel veins; petiole up to 3.5(–5) cm long, grooved above; blade oblong-elliptical to obovate, 10–45 cm × (5–)9–27 cm, cuneate to rounded at base, rounded at apex, margins sometimes slightly wavy, thin-leathery, usually hairy on veins, pinnately veined with 7–11 pairs of lateral veins. Inflorescence a head 1.5–2.5 cm in diameter, many-flowered, with numerous bracts between the flowers, heads arranged in terminal cymes; peduncle up to 20 cm long, short-hairy. Flowers bisexual, regular, 5(–7)-merous, sessile, scented; calyx c. 3 mm long, tube entire to slightly wavy at apex, glabrous; corolla white to yellowish, tube 1–3 mm long, lobes ovate-triangular, 2–2.5 mm long, hairy outside; stamens inserted on corolla tube and alternating with lobes; ovary inferior, c. 2 mm long, 2-celled, style 6.5–7.5 mm long, stigma mitre-shaped. Fruit an ellipsoid to spindle-shaped capsule 8–9 mm long, many together in globose infructescences 2–3 cm in diameter, many-seeded. Seeds angular, c. 2 mm long, slightly winged.
Other botanical information
Mitragyna comprises about 10 species, of which 6 in tropical Asia and 4 in tropical Africa. Three of the African species have been placed in a separate genus Hallea (later called Fleroya because Hallea was considered an illegitimate name), but molecular and morphological data support the inclusion in Mitragyna. Mitragyna stipulosa closely resembles Mitragyna ledermannii (K.Krause) Ridsdale, of which the distribution area partly overlaps. In the field, these two species are often indistinguishable, differing mainly in calyx characters. However, there are ecological differences, Mitragyna ledermannii occurring in more wet forest zones.
Mitragyna rubrostipulata (K.Schum.) Havil. (synonyms: Fleroya rubrostipulata (K.Schum.) Y.F.Deng, Hallea rubrostipulata (K.Schum.) J.-F.Leroy) is a small to medium-sized tree up to 20(–35) m tall, occurring in swamp forest and wet upland forest up to 2200 m altitude from eastern DR Congo east to southern Ethiopia, Kenya and Tanzania, and south to Malawi, Zambia and northern Mozambique. The pinkish brown wood is locally used for construction, flooring, moulding and canoes, and also as firewood and for charcoal production. Mitragyna rubrostipulata is considered useful for planting in degraded vegetation along upland rivers. Bark and leaf decoctions and macerations are used in traditional medicine to treat fever (including malaria), stomach-ache, colic, diarrhoea, dysmenorrhoea, menorrhagia and liver complaints, and as purgative, emetic and oxytocic. Leaf powder is applied in cases of skin diseases, and fruit extracts are taken to treat asthma.
The wood of Mitragyna inermis (Willd.) Kuntze, a small tree occurring from Mauritania east to Sudan, is mainly used for smaller artefacts, but this species is much more important as medicinal plant.
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; 25: intervessel pits small (4–7 μm); (26: intervessel pits medium (7–10 μm)); 29: vestured pits; 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; 42: mean tangential diameter of vessel lumina 100–200 μm; 47: 5–20 vessels per square millimetre; (48: 20–40 vessels per square millimetre). Tracheids and fibres: 62: fibres with distinctly bordered pits; 63: fibre pits common in both radial and tangential walls; 66: non-septate fibres present; 69: fibres thin- to thick-walled; 70: fibres very thick-walled. Axial parenchyma: 76: axial parenchyma diffuse; 77: axial parenchyma diffuse-in-aggregates; (78: axial parenchyma scanty paratracheal); 93: eight (5–8) cells per parenchyma strand; (94: over eight cells per parenchyma strand). Rays: 97: ray width 1–3 cells; 102: ray height > 1 mm; 108: body ray cells procumbent with over 4 rows of upright and/or square marginal cells; 112: perforated ray cells present; 115: 4–12 rays per mm. Mineral inclusions: 159: silica bodies present; 160: silica bodies in ray cells.
(F.D. Kamala, A.A. Oteng-Amoako & H. Beeckman)
Growth and development
In the first 3 years after germination, the annual height growth of seedlings is up to 45 cm, but young trees of 4 years old may reach 2.7 m tall, with an average bole diameter of 4 cm. In natural stands in Uganda, the mean annual bole diameter growth of older trees has been estimated at only 3 mm.
Trees produce knee roots that may reach 45 cm above soil level, later branching to form compound structures in the mud. Flowering of trees has been recorded in Nigeria in December–February; fruits ripen about 3 months later. In Uganda fruits are ripe in July–October. Trees start producing seed when about 10 years old and approximately 10 m tall. They disperse large amounts of seed by wind, giving rise to dense beds of seedlings on exposed mud.
Ecology
Mitragyna stipulosa occurs in swamps and marshy localities, occasionally in evergreen forest on drier localities, in Uganda up to 1200 m altitude. It needs subsoil moisture during the whole year, but does not grow in swamps that are deeply flooded throughout the year. It is strongly light demanding, and dependent on open swamp sites for regeneration. In Uganda it occurs in areas with an annual rainfall of about 1200 mm and temperatures of 10–33°.
Propagation and planting
The very light seeds of Mitragyna stipulosa are often difficult to collect because they are often already dispersed by wind before the fruits fall. The 1000-seed weight is about 1 g. Nearly ripe infructescences should be collected from trees and dried in the sun on polyethylene, from where seed can be collected after the fruits have opened. Seed can be stored for some time in sealed containers in a cool place, but after 10 months the germination rate was less than 1%. Seed is very susceptible to fungal attack. Seeds germinate rapidly, under wet and sunny conditions in 1–2 weeks. Under natural conditions, seedling mortality is often high due to competition from other plants and insect attacks.
Root suckers can also be used for propagation. Wildlings may be abundant around mother trees and can be collected for propagation. They are mainly found on exposed soil mounds rising above the water level. Young plantations need good care during the first years to counteract too much competition by other fast-growing plant species. Cuttings appeared to be very susceptible to fungal infection.
Management
Locally Mitragyna stipulosa occurs in high densities. In swamp forest in Uganda it may be found in nearly pure stands and is locally dominant in the upper canopy. It is particularly gregarious in the narrow belt of swamp forest fringing the papyrus swamps at the north-western shores of Lake Victoria.
Trees coppice freely at all growth stages when light conditions are suitable. They can be pollarded. Based on measurements in Uganda, very long rotation cycles would be needed to harvest boles of 80 cm in diameter, varying from 100 years to 250 years. A clear-felling system would be needed to obtain good regeneration.
Harvesting
The swamp forest, which is the usual habitat for Mitragyna stipulosa, requires special equipment for harvesting. Boles may have spongy heart and therefore some caution is needed at felling. The minimum bole diameter for harvesting is 60 cm in Cameroon, 70 cm in Ghana and 80 cm in Liberia.
Handling after harvest
Freshly harvested logs float in water and can be transported by river. Logs have a tendency to end splitting and should be sealed if not converted immediately.
Genetic resources
Mitragyna stipulosa is in general locally common in its specific habitat, but it has been heavily overexploited in many areas within its range. It is therefore classified as vulnerable in the IUCN Red List of threatened species. In Uganda it is considered threatened.
Prospects
Apart from its usefulness as a source of commercially important timber and of traditional medicine, Mitragyna stipulosa has potential for reforestation in swampy areas, where it can play an important role in water management and erosion control. More information is needed on its silvicultural management to draw up regulations for sustainable management, taking into consideration that it often grows in fragile aquatic ecosystems. Several pharmacological properties deserve more research attention for potential drug development, especially the antihypertensive and antibacterial activities.
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.
• Bridson, D. & Verdcourt, B., 1988. Rubiaceae (part 2). In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. pp. 415–747.
• Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Volume 4, Families M–R. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 969 pp.
• Hawthorne, W.D., 1995. Ecological profiles of Ghanaian forest trees. Tropical Forestry Papers 29. Oxford Forestry Institute, Department of Plant Sciences, University of Oxford, United Kingdom. 345 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.
• McCarthy, J., 1961. Growth conditions and regeneration of abura (Mitragyna stipulosa). Empire Forestry Review 40: 124–133.
• Oteng-Amoako, A.A. (Editor), 2006. 100 tropical African timber trees from Ghana: tree description and wood identification with notes on distribution, ecology, silviculture, ethnobotany and wood uses. 304 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
• Taylor, C.J., 1960. Synecology and silviculture in Ghana. Thomas Nelson and Sons, Edinburgh, United Kingdom. 418 pp.
• Zigah, F., 2000. Investigation of antimicrobial activity of the leaves, the stem bark and the root bark of Hallea stipulosa. B. Pharm. Degree thesis, faculty of Pharmacy, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. 50 pp.
Other references
• ATIBT (Association Technique Internationale des Bois Tropicaux), 1986. Tropical timber atlas: Part 1 – Africa. ATIBT, Paris, France. 208 pp.
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome troisième. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 334 pp.
• 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.
• Chilufya, H. & Tengnäs, B., 1996. Agroforestry extension manual for northern Zambia. Regional Soil Conservation Unit, Nairobi, Kenya. 120 + 124 pp.
• CIRAD Forestry Department, 2009. Abura. [Internet] Tropix 6.0. http://tropix.cirad.fr/ africa/abura.pdf. Accessed June 2010.
• Fatima, N., Tapondjou, L.A., Lontsi, D., Sondengam, B.L., Atta-Ur-Rahman & Choudhary, M.I., 2002. Quinovic acid glycosides from Mitragyna stipulosa - first examples of natural inhibitors of snake venom phosphodiesterase I. Natural Products Letters 16(6): 389–393.
• Hallé, N., 1966. Rubiacées (1re partie). Flore du Gabon. Volume 12. Muséum National d’Histoire Naturelle, Paris, France. 278 pp.
• Hawthorne, W., 1990. Field guide to the forest trees of Ghana. Natural Resources Institute, for the Overseas Development Administration, London, United Kingdom. 275 pp.
• Hawthorne, W. & Jongkind, C., 2006. Woody plants of western African forests: a guide to the forest trees, shrubs and lianes from Senegal to Ghana. Kew Publishing, Royal Botanic Gardens, Kew, United Kingdom. 1023 pp.
• Irvine, F.R., 1961. Woody plants of Ghana, with special reference to their uses. Oxford University Press, London, United Kingdom. 868 pp.
• Iwu, M.M., 1993. Handbook of African medicinal plants. CRC Press, Boca Raton, Florida, United States. 464 pp.
• Keay, R.W.J., 1989. Trees of Nigeria. A revised version of Nigerian trees (1960, 1964) by Keay, R.W.J., Onochie, C.F.A. & Stanfield, D.P. Clarendon Press, Oxford, United Kingdom. 476 pp.
• Latham, P., 2004. Useful plants of Bas-Congo province, Democratic Republic of the Congo. DFID, London, United Kingdom. 320 pp.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Omagor, N., 1999. Swamp forest plant resources in Uganda: their uses and conservation challenges. International Tree Crops Journal 10(2): 107–120.
• Razafimandimbison, S.G. & Bremer, B., 2002. Phylogeny and classification of Naucleeae s.l. (Rubiaceae) inferred from molecular (ITS, rBCL, and tRNT-F) and morphological data. American Journal of Botany 89: 1027–1041.
• Savill, P.S. & Fox, J.E.D., 1967. Trees of Sierra Leone. Forest Department, Freetown, Sierra Leone. 316 pp.
• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.
• Voorhoeve, A.G., 1979. Liberian high forest trees. A systematic botanical study of the 75 most important or frequent high forest trees, with reference to numerous related species. Agricultural Research Reports 652, 2nd Impression. Centre for Agricultural Publishing and Documentation, Wageningen, Netherlands. 416 pp.
• World Conservation Monitoring Centre, 1998. Hallea stipulosa. In: IUCN. Red list of threatened species. Version 2010.1. [Internet] http://www.iucnredlist.org. Accessed July 2010.
Sources of illustration
• Hawthorne, W. & Jongkind, C., 2006. Woody plants of western African forests: a guide to the forest trees, shrubs and lianes from Senegal to Ghana. Kew Publishing, Royal Botanic Gardens, Kew, United Kingdom. 1023 pp.
• Keay, R.W.J., 1989. Trees of Nigeria. A revised version of Nigerian trees (1960, 1964) by Keay, R.W.J., Onochie, C.F.A. & Stanfield, D.P. Clarendon Press, Oxford, United Kingdom. 476 pp.
Author(s)
Nyunaï Nyemb
Institut de Recherches Médicales et d’Etudes des Plantes Médicinales, B.P. 3805, Yaoundé, Cameroon


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:
Nyemb, Nyunaï, 2011. Mitragyna stipulosa (DC.) Kuntze. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). Prota 7(2): Timbers/Bois d’œuvre 2. [CD-Rom]. PROTA, Wageningen, Netherlands.
Distribution Map wild


1, flowering twig; 2, flower; 3, fruits.
Redrawn and adapted by Iskak Syamsudin



Mitragyna stipulosa


Mitragyna stipulosa


Mitragyna stipulosa


Mitragyna stipulosa


wood in transverse section


wood in tangential section


wood in radial section


transverse surface of wood