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Antiaris toxicaria Lesch.

Protologue
Ann. Mus. Natl. Hist. Nat. 16: 478, pl. 22 (1810).
Family
Moraceae
Chromosome number
2n = 24, 28
Vernacular names
Antiaris, bark cloth tree, false iroko (En). Ako (Fr). Pó de bitcho, pó de leite (Po). Mkunde (Sw).
Origin and geographic distribution
Antiaris toxicaria is extremely widespread, being found throughout the Old World tropics. In Africa it occurs from Senegal east to southern Ethiopia, and south to Zambia and Angola; it is also found in Madagascar. It occurs in tropical Asia, islands of the Pacific Ocean (east to Fiji and Tonga) and northern Australia.
Uses
The wood is used for interior joinery, panelling, moulding, shuttering, furniture, strip flooring, boxes and crates, tool handles, toys, carvings, peeled and sliced veneer for interior and exterior parts of plywood, fibre and particle board, and blockboard. It is fairly commonly used domestically for light construction and canoes. It is locally popular for drum making, e.g. in Uganda. The wood from the roots is sometimes used as a cork substitute.
The bark yields a latex which is one of the principle components of most dart and arrow poisons in South-East Asia. In Africa the latex is applied to cuts, wounds and skin complaints such as eczema and leprosy, and is taken internally as a purgative. It is also reported to be used as a fish poison and birdlime. Seeds, leaves and bark are used as a febrifuge and the seeds also as an antidysenteric. The bark is used as an anodyne and vermifuge, and to treat hepatitis. It has also been used for dyeing. The inner bark is used to make rough clothing, hammocks, sandals, hut walls, cordage, sacks, mats and paper. The fruit is edible. The leaves are used as fodder. Antiaris toxicaria is sometimes planted as a roadside tree.
Production and international trade
The export of Antiaris toxicaria timber from West Africa started in 1959, when 1600 m³ of logs were exported. It increased to 40,000 m³ in 1963; in 1973 66,000 m³ was exported from Côte d’Ivoire and in 1983 165,000 m³. After 1983, the export decreased rapidly. At present, Antiaris toxicaria is most important on the international market for its veneer and plywood. In 2001 Ghana exported 4000 m³ of veneer at an average price of US$ 524/m³, and in 2002 it exported 2000 m³ at an average price of US$ 463/m³; the export of plywood from Ghana was 13,000 m³ in 2001 and 9000 m³ in 2002 at an average price of US$ 268/m³. The wood of Antiaris toxicaria is often traded in mixed consignments of lightweight hardwood.
Properties
Heartwood whitish to pale yellow or pale yellow-brown, indistinctly demarcated from the sapwood, which is up to 8 cm thick. The grain is interlocked, texture moderately coarse. The wood has a ribbon-like aspect on quarter-sawn faces, and is lustrous. Fresh wood has woolly surfaces.
The wood of Antiaris toxicaria is a lightweight hardwood. The density is 370–480(–660) kg/m³ at 12% moisture content. The shrinkage rates are moderate, from green to 12% moisture content 2.2% radial and 4.3% tangential, and from green to oven dry 3.3–4.6% radial and 5.8–8.2% tangential. The timber dries moderately easily and rapidly, with rather high risk of distortion for flat-sawn boards and slight risk of checking. Once dry, the wood is moderately stable in service.
At 12% moisture content, the modulus of rupture is 42–98 N/mm², modulus of elasticity 5700–10,000 N/mm², compression parallel to grain 28–53 N/mm², shear 3–9 N/mm², cleavage 10–17 N/mm, Janka side hardness 1690–5610 N and Janka end hardness 2270–6630 N.
The wood works easily with hand and machine tools; ordinary saw teeth and cutting tools can be used, but these should be kept sharp to prevent crumbling, particularly along the edges. A smooth finish can be obtained, but with some tearing due to interlocked grain. The peeling and slicing properties are good, but rotary-peeled veneer is somewhat brittle. The wood stains and polishes well. Filling is recommended to obtain a good finish. The nailing and screwing properties are satisfactory. Gluing does not cause problems.
The wood is not durable. It is liable to fungal attack (e.g. blue stain), and susceptible to termites and dry-wood borers; the sapwood is liable to powder-post beetle attack. The wood should not be used in contact with the ground or exposed to the weather. It is easy to treat with preservatives using either open tank or pressure systems; a retention of 455 kg/m³ has been determined for heartwood and 540 kg/m³ for sapwood. The sawdust may cause skin irritation and occupational asthma.
The latex is reported to be a mild circulatory and cardiac stimulant when used in very small amounts, but in large amounts it is a myocardial poison. The active principles are cardiac glycosides (cardenolides), e.g. α-antiarin, β-antiarin and γ-antiarin, which have digitalis-like effects on the heart. In larger amounts they lead to cardiac arrest and secondary effects such as vomiting and convulsions. Reports on lethal dosage, administered intravenously, specify 0.3 mg as lethal within 12 minutes for a rabbit, and 1 mg within 3–9 minutes in dogs. Tests with animals suggest that the cardiac glycosides affect Na+K+ATPase activity of the heart muscle-cells. The poison must enter the bloodstream to be effective; the latex can be ingested without any effects. Reports claim that the latex from African trees is less poisonous or even innocuous. It is possible that these reports refer to the latex being used differently, not as a dart or arrow poison as in South-East Asia, and thus not entering the bloodstream. An aqueous ethanol extract of the bark exhibited cytotoxic activity against tumour cell lines.
Adulterations and substitutes
The wood of Antiaris toxicaria resembles that of Triplochiton scleroxylon K.Schum. and can be used as a substitute for the latter. It can also be used as a substitute for Terminalia superba Engl. & Diels and Pterygota macrocarpa K.Schum. wood.
Description
Deciduous, monoecious, small to large tree up to 45(–60) m tall; bole straight, branchless for up to 25(–33) m, up to 180 cm in diameter, sometimes with steep buttresses up to 3 m high; bark surface smooth becoming slightly fissured, greyish white to greyish green, with numerous lenticels, inner bark soft and fibrous, exuding a creamy latex soon darkening to dirty brown; crown fairly small, dome-shaped; twigs hairy. Leaves alternate, more or less distichous, simple; stipules free, up to 1(–1.5) cm long, caducous; petiole up to 1 cm long, hairy; blade elliptical to oblong or obovate, (4–)6–20(–30) cm × 3–12 cm, obtuse to slightly cordate and slightly unequal at base, obtuse to shortly acuminate at apex, entire to slightly toothed, thinly leathery to leathery, hairy, pinnately veined with lateral veins in (5–)7–14 pairs. Inflorescence on a short shoot in or below the leaf axils, 1–8 together, male ones 0.5–1(–2) cm in diameter, many-flowered, female ones 3–4 mm in diameter, 1-flowered, subtended by involucral bracts. Flowers unisexual; male flowers with (2–)3–5(–7) free tepals and 2–4 stamens; female flowers with 4-lobed perianth and 1-celled ovary adnate to the perianth, styles 2, long. Fruit forming a drupe-like, ellipsoid to ovoid or globose entity together with the enlarged, fleshy orange to scarlet receptacle, 1–1.5(–2) cm long, 1-seeded. Seed globose to ellipsoid, 7–9 mm long, with thin seed coat, veined near hilum. Seedling with hypogeal germination; cotyledons thick, fleshy; epicotyl with a few scale leaves, followed by spirally arranged, toothed leaves.
Other botanical information
Antiaris comprises a single variable species, which is subdivided into 5 subspecies. Two of these occur in tropical Asia and islands of the Pacific, two in Madagascar: subsp. madagascariensis (H.Perrier) C.C.Berg (synonym: Antiaris madagascariensis H.Perrier) and subsp. humbertii (Leandri) C.C.Berg (synonym: Antiaris humbertii Leandri), and one in mainland Africa: subsp. welwitschii (Engl.) C.C.Berg (synonym: Antiaris welwitschii Engl.). Within the latter subspecies 3 varieties are distinguished based on differences of texture, indumentum and venation of the leaves: var. welwitschii (Engl.) Corner widely distributed in rainforest, var. africana A.Chev. (synonym: Antiaris africana Engl.) widely distributed in drier habitats, and var. usambarensis (Engl.) C.C.Berg (synonym: Antiaris usambarensis Engl.) from eastern DR Congo, Kenya, Uganda and Tanzania. However, intermediates are rather common.
Anatomy
Wood-anatomical description (IAWA hardwood codes):
Growth rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; 22: intervessel pits alternate; (23: shape of alternate pits polygonal); 26: intervessel pits medium (7–10 μm); 27: intervessel pits large ( 10 μm); 31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular; 42: mean tangential diameter of vessel lumina 100–200 μm; 43: mean tangential diameter of vessel lumina 200 μm; 46: 5 vessels per square millimetre; 47: 5–20 vessels per square millimetre. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 65: septate fibres present; 69: fibres thin- to thick-walled. Axial parenchyma: 79: axial parenchyma vasicentric; 80: axial parenchyma aliform; 81: axial parenchyma lozenge-aliform; 83: axial parenchyma confluent; 92: four (3–4) cells per parenchyma strand; 93: eight (5–8) cells per parenchyma strand. Rays: 98: larger rays commonly 4- to 10-seriate; (102: ray height > 1 mm); 106: body ray cells procumbent with one row of upright and/or square marginal cells; (107: body ray cells procumbent with mostly 2–4 rows of upright and/or square marginal cells); (110: sheath cells present); 115: 4–12 rays per mm. Secretory elements and cambial variants: 132: laticifers or tanniferous tubes. Mineral inclusions: (136: prismatic crystals present); (137: prismatic crystals in upright and/or square ray cells); (141: prismatic crystals in non-chambered axial parenchyma cells).
(M. Thiam, P. Détienne & E.A. Wheeler)
Growth and development
Antiaris toxicaria is a non-pioneer light demander. Seedlings are usually abundant near the mother tree, but experience high mortality in the first year. In the shade of the forest, seedlings up to 40 cm tall are common, but exposure to full light is required for further growth. Under exposed conditions, the tree can grow rapidly; growth rates of 50 cm/year in height are common in abandoned farmland. Mean annual diameter growth can reach 1 cm. Antiaris toxicaria has a good self-pruning ability. In West Africa trees lose their leaves between November and February, and in this period flowering occurs. However, in wetter types of forest, trees can be more or less evergreen. Fruits are ripe in February–March. Trees usually do not fruit until at least 40 cm in bole diameter. The seeds are dispersed by animals such as birds, monkeys and antelopes, which relish the fruits.
Ecology
Antiaris toxicaria is found from the wettest to dry forest types, from wet evergreen forest to dry deciduous forest, and even in wooded grassland. It is often common in secondary forest, and is an emergent tree of the high forest. In the wetter types of forest, it seems to prefer well-drained sites. Antiaris toxicaria can be found from sea-level to 1800 m altitude. It has no special soil requirements. In the driest forest types (e.g. in southern Mali and Burkina Faso) it is frequently associated with Milicia excelsa (Welw.) C.C.Berg and Ceiba pentandra (L.) Gaertn.
Propagation and planting
Fresh seed has a high germination rate, up to 94% in 2.5–13 weeks. Under natural conditions, the seeds lose viability rapidly, but when stored in wet sand at low temperatures they still may have a germination rate of 82% after 5 months. In an experimental plantation in northern Côte d’Ivoire, the survival rate of seedlings after 3.5 years was only 49% and the average height only 60 cm because of high grazing pressure of cattle and wild animals; planting of 2 m-tall seedlings was recommended.
Management
Stands of Antiaris toxicaria are managed under selective logging systems, and removal of trees is based on prescribed silvicultural parameters such as minimum felling diameter, cutting cycle and felling intensity, which depend on stocking in the various countries.
Diseases and pests
The psyllid Triozamia lamborni is the most important pest of Antiaris toxicaria. All stages of the insect can attack the plant, but the greatest damage is done by the nymphs, which kill the apical points of suckers or seedlings, causing dieback, shedding of leaves, and sometimes death.
Harvesting
Trees are harvested by power chain saw and the logs are subsequently cross cut. The log parts are skidded to log yards, from where they are transported to processing mills or to the port for export.
In tropical Asia the latex is tapped by making scores in the bark with a knife. It is usually collected when required as arrow poison or for medicinal purposes, as it is generally used fresh and only occasionally dried for later use. The bark is harvested by stripping from the tree.
Yield
The total stock volume above 30 cm diameter at breast height was estimated in 2001 in Ghana at 825 m³/km², and that above the minimum felling diameter of 70 cm at 166 m³/km². The latex yield of a scarred tree may be 100–500 g in 2 days.
Handling after harvest
Rapid conversion and the application of anti-stain chemicals upon felling and immediately after sawing are essential, as the wood is liable to sap-stain; it can become stained up to 15 cm deep. The wood may also be seriously damaged by various insects if it is not quickly converted or treated with preservatives.
In tropical Asia the latex from the bark is mixed with other ingredients such as bark or roots of Strychnos and Derris spp. The mixture is boiled over a fire to obtain a thick paste in which the dart and arrow points are dipped. Bark cloth is obtained by shaving off the outer part from bark stripped from the tree, and beating and washing the inner fibrous part. Careful preparation is required because traces of latex may irritate the skin.
Genetic resources
Antiaris toxicaria is extremely widespread and consequently not easily liable to genetic erosion. However, in tropical Asia it is not common, with usually only low densities in the forest. In Africa it is generally much more common, but local exploitation has severely reduced populations. The great variability of the species should be studied in more detail, also in relation to its wood and chemical properties and ecology.
Prospects
Antiaris toxicaria is still a poorly known timber tree; in Ghana it is on the list of lesser-used species which are currently being promoted. Studies of its technological and investment profile may pave the way for increased utilization as a commercial timber. Its fast growth and ease of propagation make it a potential plantation species.
Major references
• Agyeman, V.K., Ayarkwa, J., Owusu, F.W., Boachie-Dapaah, A.S.K., Addae-Mensah, A., Appiah, S.K., Oteng Amoako, A., Adam, A.R. & Pattie, D., 2003. Technological and investment profiles of some lesser used timber species in Ghana. Publication of International Tropical Timber Organization and Forestry Research Institute of Ghana, Accra, Ghana. 85 pp.
• Boer, E., Brink, M. & Sosef, M.S.M., 1999. Antiaris toxicaria Lesch. In: de Padua, L.S., Bunyapraphatsara, N. & Lemmens, R.H.M.J. (Editors). Plant Resources of South-East Asia No 12(1). Medicinal and poisonous plants 1. Backhuys Publishers, Leiden, Netherlands. pp. 126–129.
• Boer, E. & Sosef, M.S.M., 1998. Antiaris Lesch. In: Sosef, M.S.M., Hong, L.T. & Prawirohatmodjo, S. (Editors). Plant Resources of South-East Asia No 5(3). Timber trees: Lesser-known timbers. Backhuys Publishers, Leiden, Netherlands. pp. 73–75.
• 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.
• Chudnoff, M., 1980. Tropical timbers of the world. USDA Forest Service, Agricultural Handbook No 607, Washington D.C., United States. 826 pp.
• CIRAD Forestry Department, 2003. Ako. [Internet] Tropix 5.0. http://tropix.cirad.fr/ afr/ako.pdf. Accessed June 2005.
• 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.
• Richter, H.G. & Dallwitz, M.J., 2000. Commercial timbers: descriptions, illustrations, identification, and information retrieval. [Internet]. Version 18th October 2002. http://delta-intkey.com/wood/index.htm. Accessed June 2005.
• Siepel, A., Poorter, L. & Hawthorne, W.D., 2004. Ecological profiles of large timber species. In: Poorter, L., Bongers, F., Kouamé, F.N. & Hawthorne, W.D. (Editors). Biodiversity of West African forests. An ecological atlas of woody plant species. CABI Publishing, CAB International, Wallingford, United Kingdom. pp. 391–445.
• 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.
Other references
• Akanbi, M.O., 1980. Preliminary notes on Triozamia lamborni (Newstead) (Hem., Psyllidae), a potentially dangerous pest of Antiaris africana. Entomologist’s Monthly Magazine 116: 1392–1395.
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome premier. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 369 pp.
• Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
• Berg, C.C., 1977. Revisions of African Moraceae (excluding Dorstenia, Ficus, Musanga and Myrianthus). Bulletin du Jardin Botanique National de Belgique 47(3–4): 267–407.
• Berg, C.C., 1991. Moraceae. In: Launert, E. & Pope, G.V. (Editors). Flora Zambesiaca. Volume 9, part 6. Flora Zambesiaca Managing Committee, London, United Kingdom. pp. 13–76.
• Berg, C.C. & Hijman, M.E.E., 1989. Moraceae. In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 95 pp.
• Berg, C.C., Hijman, M.E.E. & Weerdenburg, J.C.A., 1984. Moraceae. Flore du Gabon. Volume 26. Muséum National d’Histoire Naturelle, Paris, France. 276 pp.
• Berg, C.C., Hijman, M.E.E. & Weerdenburg, J.C.A., 1985. Moraceae (incl. Cecropiaceae). Flore du Cameroun. Volume 28. Muséum National d’Histoire Naturelle, Paris, France. 298 pp.
• InsideWood, undated. [Internet] http://insidewood.lib.ncsu.edu/search/. Accessed May 2007.
• Irvine, F.R., 1961. Woody plants of Ghana, with special reference to their uses. Oxford University Press, London, United Kingdom. 868 pp.
• Kerharo, J. & Adam, J.G., 1974. La pharmacopée sénégalaise traditionnelle. Plantes médicinales et toxiques. Vigot & Frères, Paris, France. 1011 pp.
• Raponda-Walker, A. & Sillans, R., 1961. Les plantes utiles du Gabon. Paul Lechevalier, Paris, France. 614 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
• Wagenfuhr, R., 1979. A structural peculiarity of Antiaris africana Engl. IAWA Bulletin 4: 86.
• Wilks, C. & Issembé, Y., 2000. Les arbres de la Guinée Equatoriale: Guide pratique d’identification: région continentale. Projet CUREF, Bata, Guinée Equatoriale. 546 pp.
• World Agroforestry Centre, undated. Agroforestree Database. [Internet] World Agroforestry Centre (ICRAF), Nairobi, Kenya. http://www.worldagroforestry.org/ resources/databases/ agroforestree. Accessed June 2005.
Sources of illustration
• Berg, C.C., 1977. Revisions of African Moraceae (excluding Dorstenia, Ficus, Musanga and Myrianthus). Bulletin du Jardin Botanique National de Belgique 47(3–4): 267–407.
• Wilks, C. & Issembé, Y., 2000. Les arbres de la Guinée Equatoriale: Guide pratique d’identification: région continentale. Projet CUREF, Bata, Guinée Equatoriale. 546 pp.
Author(s)
P.P. Bosu
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
E. Krampah
Kumasi, Ghana


Editors
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
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
J.R. Cobbinah
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
Photo editor
E. Boer
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Bosu, P.P. & Krampah, E., 2005. Antiaris toxicaria Lesch. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
Distribution Map wild


1, base of bole; 2, twig with male inflorescences; 3, twig with female inflorescences; 4, part of fruiting twig.
Redrawn and adapted by Iskak Syamsudin



tree habit


bark
obtained from Botanypictures



leafy branch
obtained from Botanypictures



leaf scar


harvesting latex
obtained from Coconutstudio



various parts of the tree
obtained from W.D. Hawthorne



fruit
obtained from Tropicos



wood in transverse section


wood in tangential section


wood in radial section


transverse surface of wood