Prota 7(2): Timbers/Bois d’œuvre 2
Bull. Mens. Soc. Linn. Paris 1: 561 (1886).
Rhodoclada rhopaloides Baker (1884).
Manoka jaune (Fr).
Origin and geographic distribution
Asteropeia rhopaloides occurs in northern and eastern Madagascar, as far south as the surroundings of Andasibe.
The wood is known as ‘manoka’, and used for house and bridge construction, especially as poles, and for joinery, railway sleepers and carvings. It is suitable for heavy flooring, interior trim, mine props, ship building, vehicle bodies, sporting goods, agricultural implements and turning.
The heartwood is pale yellowish brown and usually distinctly demarcated from the paler sapwood. The grain is straight or interlocked, texture fine and even. The wood is heavy, with a density of 900–1020 kg/m³ at 12% moisture content. Air drying is slow but usually with little degrade, although the rates of shrinkage are rather high, from green to oven dry about 6% radial and 11.5% tangential.
At 12% moisture content, the modulus of rupture is 169–226 N/mm², modulus of elasticity 15,800–18,000 N/mm², compression parallel to grain 85–89 N/mm², shear about 8.5 N/mm², cleavage 7.5–18 N/mm and Chalais-Meudon side hardness 7. 8–12.4.
The wood is fairly easy to saw when stellite-tipped saw teeth are used. It takes an excellent polish, but picking up of grain may occur in planing when interlocked grain is present. Pre-boring is needed for nailing; the wood is liable to splitting. The wood glues with some difficulty, but varnishes and waxes well. It is very durable, being resistant to fungal and termite attacks. The heartwood is resistant to impregnation by preservatives, but the sapwood is only moderately resistant.
Evergreen small to medium-sized tree up to 25(–30) m tall; bole up to 75 cm in diameter; bark surface dark grey to blackish, inner bark granular; young twigs rusty brown short-hairy. Leaves arranged spirally, simple and entire; stipules absent; petiole 5–7 mm long, thick; blade obovate to oblong, 4.5–9 cm × 2.5–5 cm, cuneate at base, rounded or notched, sometimes slightly acuminate at apex, leathery, glabrous, pinnately veined. Inflorescence a terminal, deltoid panicle up to 9 cm long, rusty brown short-hairy. Flowers bisexual, regular, 5-merous; pedicel 1–3 mm long, jointed; sepals free, ovate-oblong, 2–2.5 mm long but enlarging up to 6 mm in fruit; petals free, oblong, c. 4 mm long, caducous; stamens 10, free, up to 4 mm long; ovary superior, incompletely 3-celled, style cylindrical, with 3 stigmas. Fruit a globose capsule c. 4 mm long, finely warty, glabrous, irregularly dehiscent, 1-seeded.
Asteropeia rhopaloides flowers from October to December. The flowers are probably pollinated by insects.
Asteropeia comprises 8 species and is endemic to Madagascar. The wood of some other species reaching the size of a medium-sized tree, such as Asteropeia mcphersonii G.E.Schatz, Lowry & A.-E.Wolf and Asteropeia multiflora Thouars, is known as ‘andrampotsy’ or ‘manoka fotsy’ and used for similar purposes as that of Asteropeia rhopaloides, and it seems to be easier to work. The bark of Asteropeia mcphersonii is additionally used in traditional medicine as a tonic.
Asteropeia rhopaloides is found in evergreen humid forest at 800–1400 m altitude.
The boles are often submerged in water for considerable time before they are used in construction; this reportedly makes the wood more durable.
Genetic resources and breeding
Asteropeia rhopaloides is classified in the IUCN Red List as endangered because of habitat loss by shifting cultivation and because of selective felling for timber. The number of individual trees in populations are decreasing and populations become more and more scattered and isolated. Asteropeia mcphersonii and Asteropeia multiflora are also included in the IUCN Red List, but are considered to be less immediately threatened, being classified as ‘vulnerable’ and ‘of least concern’, respectively.
Asteropeia rhopaloides and some other Asteropeia spp. yield valuable timber that is in high demand for local applications and certainly also on the international market. However, being species restricted to vulnerable forest types in Madagascar and with a long history of exploitation, it seems unwise to promote them for increased utilization. Protection should be the primary consideration, and research should focus on propagation and planting methods as well as growth and development before the possibilities for future use in timber plantations can be judged.
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Correct citation of this article:
Lemmens, R.H.M.J., 2009. Asteropeia rhopaloides (Baker) Baill. 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.