Prota 7(1): Timbers/Bois d’œuvre 1
Bull. Misc. Inform. Kew 1925: 258 (1925).
Cassipourea elliottii (Engl.) Alston (1925), Cassipourea congoensis auct. non DC.
Pillarwood, common onionwood, bastard onionwood (En).
Origin and geographic distribution
Cassipourea malosana occurs from eastern DR Congo and Ethiopia south to South Africa.
The wood of Cassipourea malosana is traded as pillarwood. It is suitable for construction, flooring (especially heavy duty or industrial flooring), vehicle bodies, furniture and cabinet work, tool handles, ladders, sporting goods, agricultural implements, joinery, sleepers, poles and piles, toys and novelties, beehives, turnery, and for veneer and plywood. Its low durability, however, limits its applicability outdoors. Nevertheless, Cassipourea malosana is an important timber tree in East Africa. The wood is also used as firewood.
The Loita Maasai people in Kenya eat the outer bark boiled with soup to gain strength. Tea is made from the scraped inner bark; it is drunk by women to help to remove the placenta. In South Africa the bark is used as a skin lightener, and to treat skin ailments and sunburn. The flowers are a good source of nectar for bees. Cassipourea malosana is also used as a shade tree.
The heartwood varies in colour, from whitish to brown, often with purple streaks associated with fungal attack; it is indistinctly demarcated from the sapwood. The grain is usually straight, but with a slight to marked tendency to spiralling; texture fine and even. Freshly cut wood smells like onion. The wood has a density of 600–840 kg/m³ at 12% moisture content. Shrinkage rates are 3.5% radial and 8.0% tangential from green to 12% moisture content. The wood is refractory in seasoning due to high shrinkage and the presence of spiral grain. It dries slowly and is subject to severe distortion, particularly twist; checking is slight. At 12% moisture content, the modulus of rupture is 93–123 N/mm², modulus of elasticity 11,500–12,500 N/mm², compression parallel to grain 61–76 N/mm², shear 9.8–18.5 N/mm², cleavage 16–79 N/mm radial and 30–114 N/mm tangential, and Janka side hardness 5960–7345 N.
The green timber may be difficult to saw as it has a strong tendency to spring. Dry wood is easier to work than green wood. The wood is resistant to wear and abrasion. It is moderately easy to work using hand tools and has excellent machining properties, especially in moulding, but it may have an appreciable blunting effect on tool edges. A good finish can be obtained. The wood tends to split on nailing, and pre-boring is necessary. The wood may be somewhat troublesome to glue and is not suitable for steam bending.
The durability is low. The wood is susceptible to attacks by termites and Lyctus borers. The heartwood is resistant to impregnation, the sapwood moderately resistant.
Evergreen shrub or small to large tree up to 45 m tall; bole up to 21 m long, straight, cylindrical, up to 60 cm in diameter, without buttresses; bark grey, greyish yellow or brown, smooth, inner layer of outer bark bright red on exposure, inner bark orange with white striations, exudate watery; crown small, rounded; young branches hairy, later glabrous. Leaves opposite, simple; stipules between the petioles, 2–5 mm long; petiole 2–8 mm long; blade oblanceolate, lanceolate, elliptical, oblong, ovate or obovate, 2.5–10 cm × 1–6 cm, base cuneate or obtuse, apex obtuse to acute or acuminate, margin toothed or rarely entire, shiny and glabrous above, dull and sparsely pubescent to glabrous below. Inflorescence an axillary fascicle, lax to congested, 1–5(–8)-flowered. Flowers bisexual, regular, 4–5(–6)-merous; pedicel 2–6(–9) mm long, jointed near apex; calyx with tube 0.5–2 mm long, lobes narrowly oblong-triangular, 3–6 mm long, hairy outside; petals spatulate, 4–8 mm long, deeply fringed, white, yellowish or greenish; stamens 15–20(–22); ovary superior, glabrous to apically hairy, 3–4-celled, style 3–5 mm long and persistent. Fruit an ellipsoid to ovoid capsule 6–10 mm × 4–6 mm, black when dry, hairy but becoming almost glabrous, dehiscent, few-seeded. Seeds with aril, testa leathery.
Other botanical information
Cassipourea comprises about 70 species, widely distributed in the tropics. The wood of Cassipourea ndando J.Léonard ex Floret, occurring in DR Congo, Rwanda, Burundi and Zambia in forest at 1650–2500 m altitude, is also used for carpentry.
The boles of many large Cassipourea malosana trees are rotten inside.
Wood-anatomical description (IAWA hardwood codes):
Growth rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; (9: vessels exclusively solitary (90% or more)); 13: simple perforation plates; (14: scalariform perforation plates); (15: scalariform perforation plates with ≤ 10 bars); 21: intervessel pits opposite; 22: intervessel pits alternate; 25: intervessel pits small (4–7 μm); 26: intervessel pits medium (7–10 μm); 31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular; 32: vessel-ray pits with much reduced borders to apparently simple: pits horizontal (scalariform, gash-like) to vertical (palisade); 41: mean tangential diameter of vessel lumina 50–100 μm; 49: 40–100 vessels per square millimetre; 58: gums and other deposits in heartwood vessels. 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); (98: larger rays commonly 4- to 10-seriate); (102: ray height > 1 mm); (103: rays of two distinct sizes); 108: body ray cells procumbent with over 4 rows of upright and/or square marginal cells; 109: rays with procumbent, square and upright cells mixed throughout the ray; 115: 4–12 rays per mm; 116: ≥ 12 rays per mm. Mineral inclusions: 136: prismatic crystals present; 137: prismatic crystals in upright and/or square ray cells.
(L.N. Banak, H. Beeckman & P.E. Gasson)
Cassipourea malosana mostly occurs in dry or humid forest at 1000–3100 m altitude. It is locally common, and in montane forests in Kenya and Tanzania it is sometimes the dominant species or co-dominant with Podocarpus latifolius (Thunb.) Mirb.
Propagation and planting
Cassipourea malosana is sometimes propagated by wildlings collected from the forest.
In view of its wide distribution Cassipourea malosana is not liable to genetic erosion.
Although the wood is not durable, not easy to work and prone to deformation during drying, Cassipourea malosana is an important local source of timber in East Africa and will probably remain so.
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Sources of illustration
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Correct citation of this article:
Brink, M., 2006. Cassipourea malosana (Baker) Alston. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, flowering twig; 2, flower; 3, part of fruiting twig; 4, fruit.
Redrawn and adapted by Iskak Syamsudin
wood in transverse section
wood in radial section
detail wood in radial section
wood in tangential section