Prota 7(1): Timbers/Bois d’œuvre 1
Journ. de Bot., sér. 2, 2: 99 (1909).
Morus lactea (Sim) Mildbr. (1922).
East African mulberry, African mulberry, Uganda mulberry (En). Difou, mûrier du Sénégal (Fr). Chocobondo (Po).
Origin and geographic distribution
Morus mesozygia has a wide distribution in tropical Africa, from Senegal eastward to Ethiopia and southward to Zambia, Angola, Mozambique and South Africa.
The wood (trade name: difou) is especially suitable for sliced veneer, high-class furniture, flooring, staircases, joinery and turnery, but also for interior trim, sporting goods, agricultural implements, toys, novelties, carvings, boxes, crates, vats, posts, poles, piles, mine props and shingles. In Ghana the wood is used for construction, furniture, joinery, mortars and pestles. In DR Congo it is traditionally used for dug-out canoes. Stems from coppiced trees are used as walking sticks, ramrods for guns and palisades. The wood is used as fuelwood and for charcoal making.
The infructescense is edible and tastes like white grapes. The fibrous bark has been made into cloth and sandals. The latex is used for making birdlime and has been used as a rubber adulterant. The leaves are fodder for livestock and the flowers provide forage for honey bees.
In African traditional medicine all plant parts are used in decoctions, baths, massages and enemas against rheumatism, lumbago, intercostal pain, neuralgia, colic, stiffness, debility, diarrhoea and dysentery. The root is used as an aphrodisiac. Sap from young shoots is dropped into the nose for treatment of syphilis.
Morus mesozygia is widely planted as a wayside tree, shade and palaver tree, and along farm and field boundaries. In Uganda it is a shade tree in coffee and banana plantations, in Côte d’Ivoire in coffee and cocoa plantations. Morus mesozygia is often credited with magical properties.
The heartwood is yellow when freshly cut, darkening to brown on exposure, and distinctly demarcated from the 5–10 cm wide, grey to white sapwood. The grain is straight to interlocked, texture fine to medium. The wood is moderately lustrous and has a mottled or ribbon-like figure.
The wood is medium-weight to heavy, with a density of 660–920(–1050) kg/m³ at 12% moisture content. The air drying characteristics are satisfactory. The rates of shrinkage from green to oven dry are moderate: 3.2–4.3(–5.0)% radial and 5.6–6.6 (–8.3)% tangential. Once dry, the wood is stable in service.
The wood is strong and hard but somewhat brittle. At 12% moisture content, the modulus of rupture is 143–213 N/mm², modulus of elasticity 14,500–18,500 N/mm², compression parallel to grain 83–92 N/mm², shear 8–9 N/mm², cleavage 16–20 N/mm and Chalais-Meudon side hardness 6.0–15.4.
The wood works moderately easily with most hand and machine tools, but with some blunting of cutting edges. It saws well, but stellite-tipped sawteeth are recommended. In planing interlocked grain may cause trouble, and quartersawn surfaces should be planed at a reduced angle (15°) to avoid picking up. Pre-boring is recommended for nailing; the nail and screw holding properties are good. Slicing properties are good, but peeling properties poor. The wood glues well and takes a good finish. Sawdust may cause dermatitis and irritation to the nose and throat.
Although the wood is sometimes said to be durable, it has also been recorded to be vulnerable to attacks by fungi, pinhole borers, marine borers, longhorn borers and termites. The sapwood is susceptible to Lyctus borer attack. The heartwood is extremely resistant to impregnation with preservatives, the sapwood moderately resistant.
The heartwood contains the flavonoids morin, dihydromorin and pinobanksin, the leaves a glycoside of morin. Resistance of the wood to the wood rot fungi Coriolus versicolor, Lentinus squarrosulus and Poria spp. is related to the presence of dihydromorin.
The chemical composition of the oven-dry wood is: cellulose 28–33%, pentosans 16–18%, lignin 26–28%, furfurals 2–10% and ash 2–3%. The solubility in hot water is 3–4%, in alcohol-benzene 13–14% and in 1% NaOH 15–20%. Sulphate pulping of the wood resulted in pulp of acceptable strength.
Adulterations and substitutes
The wood resembles that of iroko (Milicia excelsa (Welw.) C.C.Berg) and it has sometimes been exploited as such, but it has a finer texture. In Ghana it is considered a substitute of iroko.
Dioecious small to fairly large tree up to 40 m tall, with white latex; bole branchless for up to 18 m, up to 90 cm in diameter, straight, usually cylindrical, with ridges at base, sometimes with buttresses; outer bark grey to brown, with paler blotches, smooth, later longitudinally fissured, with vertical rows of large lenticels, inner bark cream-yellow, exuding latex when cut; branchlets whitish hairy or glabrous. Leaves distichously alternate, simple; stipules linear-lanceolate, 4–10 mm long, membranous, caducous; petiole 0.5–2.5 cm long, glabrescent; blade elliptical to oblong, ovate or obovate, more or less asymmetrical, 2.5–15 cm × 2–8(–10) cm, base cordate to obtuse, apex acuminate to acute, margin toothed, papery to thinly leathery, upper surface hairy on the main veins, lower surface hairy in the axils of the lateral veins, 3-veined from the base and with few lateral veins. Inflorescence an axillary spike; male inflorescence 1–3 cm long, c. 8 mm in diameter, creamy white, peduncle 0.5–3 cm long, many-flowered; female inflorescences head-like, globose, c. 0.5 cm in diameter, 3–10(–15)-flowered, peduncle 0.5–2.5 cm long. Flowers unisexual, regular, 4-merous; male flowers with tepals 2–3 mm long, fused at base, pubescent, stamens free, inflexed in bud, at anthesis bending outward elastically, ovary rudimentary; female flowers with tepals 2–3 mm long, fused at base, short-hairy, longer-hairy at margins, ovary superior, free, style with 2 stigmatic branches. Fruit an ellipsoid to globose drupe c. 5 mm × 3.5 mm, more or less compressed, enclosed in the persistent fleshy perianth, 1-seeded, several fruits together in a nearly globose infructescence c. 1 cm in diameter. Seed c. 4.5 mm × 2.5–4.5 mm, more or less compressed.
Other botanical information
Morus comprises 10–15 species, mainly distributed in the warm temperate and subtropical regions of the northern hemisphere, with only 1 species (Morus mesozygia) native to tropical Africa. Morus alba L. and Morus nigra L. have been introduced into Africa, mainly for their edible fruits and as food plants for silk worms.
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); 27: intervessel pits large (≥ 10 μm); 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular; 43: mean tangential diameter of vessel lumina ≥ 200 μm; 46: ≤ 5 vessels per square millimetre; (47: 5–20 vessels per square millimetre); 56: tyloses common. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 69: fibres thin- to thick-walled; 70: fibres very thick-walled. Axial parenchyma: 85: axial parenchyma bands more than three cells wide; (89: axial parenchyma in marginal or in seemingly marginal bands); 91: two cells per parenchyma strand; 92: four (3–4) cells per parenchyma strand. Rays: 97: ray width 1–3 cells; (98: larger rays commonly 4- to 10-seriate); 106: body ray cells procumbent with one row of upright and/or square marginal cells; 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; (154: more than one crystal of about the same size per cell or chamber).
(D. Louppe, P. Détienne & E.A. Wheeler)
Growth and development
Growth is usually fast: a height increment of almost 2 m in the first year has been recorded in unshaded nursery beds. In Côte d’Ivoire and Ghana flowering is in January, when the tree is leafless, and fruiting in February–May, at the end of the dry season. In southern Africa flowering is in September–November, and fruiting in October–December. The seeds are dispersed by birds and other animals.
Morus mesozygia occurs up to 1700 m altitude in drier evergreen forest and semi-deciduous forest, also in secondary forest, thickets and along watercourses. It does not grow in locations liable to waterlogging. Morus mesozygia is a pioneer species.
Propagation and planting
Morus mesozygia is propagated using seed, wildlings or cuttings. The 1000-seed weight is about 2 g. It is recommended to sow freshly collected seed. Seed treatment is not necessary, but germination is accelerated by soaking the seeds in water for 12 hours. Germination starts 5–12 days after sowing. Under natural conditions, seedlings are most common in very exposed sites, such as large forest gaps with substantial soil erosion.
In Senegal Morus mesozygia is sometimes planted in cultivated fields, and in Ethiopia it is left standing when forest is cleared for agriculture. Lopping and pollarding is possible. Trees used as shade tree are sometimes topped and the branches weighted down with stones to create an umbrella-shaped crown.
In view of its wide distribution in tropical Africa and its wide range of habitats, Morus mesozygia does not seem to be threatened with genetic erosion. In South Africa it is protected.
Morus mesozygia is valued as a multipurpose tree, providing wood, edible fruits, fuel and traditional medicine, and as a shade and ornamental tree. The wood is not commercially important at present, but its quality is considered high, and it has potential for further domestic and export use, especially for indoor utilisation. More investigations are needed to understand the variability in the natural durability of the wood.
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Correct citation of this article:
Toirambe Bamoninga, B. & Ouattara, B., 2008. Morus mesozygia Stapf. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, twig with male inflorescences; 2, twig with female inflorescences; 3, twig with infructescences.
Redrawn and adapted by Iskak Syamsudin
bark and slash
leaves and infructescences
wood in transverse section
wood in tangential section
wood in radial section