Sloanea rhodantha (PROTA)

The wood, known as ‘voanana’, is traditionally used for construction and planks in house construction, for joinery and furniture. Kitchen utensils such as plates, boles and spoons are produced from the buttresses, whereas the bole is used to make dug-out canoes. The wood is suitable for panelling, ceiling, lathing, poles, piles, interior trim, agricultural implements, containers, matches, turnery, veneer, plywood and particle board. Wood pulp is used for paper making and the wood for charcoal production. The fruits are used in ritual ceremonies.

Production and international trade

The wood is only used locally and not traded on the international timber market.

Properties

The heartwood is purplish red to purplish brown and distinctly demarcated from the 5–10 cm wide, yellowish white sapwood. The grain is variable but often wavy to interlocked, texture medium to coarse. The wood is medium-weight, with a density of 520–690 kg/m³ at 12% moisture content. The rates of shrinkage are rather high, from green to oven dry 2.8–4.0% radial and 7.0–10.2% tangential. Partial air drying before kiln drying is recommended. At 12% moisture content, the modulus of rupture is 108–137 N/mm², modulus of elasticity 8600–10,980 N/mm², compression parallel to grain (37–)46–54 N/mm², shear 4–6 N/mm², cleavage 13–17 N/mm and Chalais-Meudon side hardness 1.9–3.4.

The wood saws and works easily with both hand and machine tools, but in planing the presence of interlocked grain may be problematic. The bending properties are good. The wood is not durable, being susceptible to fungal and insect attacks. The sapwood is liable to blue stain attack and to Lyctus borers.

Root bark extracts showed weak inhibitory activity against strains of Plasmodium falciparum. Several phenolic compounds have been isolated as active compounds.

Description

Medium-sized to large tree up to 40 m tall; bole branchless for up to 20 m, up to 120(–200) cm in diameter, with rather thin and spreading buttresses up to 2 m high; twigs glabrous to short-hairy.
Leaves arranged spirally, more or less clustered near apex of twigs, simple; stipules minute, peg-like to linear, caducous; petiole 0.5–3.5(–6) cm long, usually jointed at apex; blade obovate, 3.5–15(–18) cm × 1.5–9.5(–11) cm, cuneate to rounded at base, obtuse to rounded or short-acuminate at apex, margins entire to slightly toothed, papery to leathery, glabrous to slightly hairy, pinnately veined with 3–7 pairs of lateral veins.
Flowers solitary in leaf axils of twigs, pendant, bisexual, regular, 4–6(–8)-merous, large and showy; pedicel 2–4.5 cm long; sepals free, triangular, 0.5–1 cm long, hairy; petals free or variably fused, 1.5–3 cm long, irregularly lobed or toothed at apex, dark pink to red; stamens numerous, 0.5–1 cm long, yellow; disk c. 1 cm in diameter, flat, hairy; ovary superior, conical, c. 0.5 cm long, hairy, (3–)4–5-celled, with a narrowly conical style up to 1 cm long.
Fruit an ovoid-oblong capsule 6–11 cm × 3–7 cm, smooth but with numerous small whitish lenticels, brown, with cushion-shaped persistent disk at base, dehiscent with (3–)4–5 woody valves, each cell with 1–10 seeds.
Seeds oblong, c. 1 cm long, black, with fleshy, irregularly lobed, orange-red aril.

Other botanical information

Sloanea comprises about 100 species and occurs in all tropical and subtropical regions except mainland Africa. Only Sloanea rhodantha is found in Madagascar.

Sloanea rhodantha is variable, particularly in leaf size and shape, in hairiness of the leaves, in shape of petals and in number of stamens. Two varieties have been distinguished; var. rhodantha has glabrous leaves below, var. dalechampioides (Baker) Capuron short-hairy.

Anatomy

Wood-anatomical description (IAWA hardwood codes):

Growth rings: 1: growth ring boundaries distinct.
Vessels: 5: wood diffuse-porous; 13: simple perforation plates; 21: intervessel pits opposite; 22: intervessel pits alternate; (23: shape of alternate pits polygonal); 27: intervessel pits large (≥ 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); 42: mean tangential diameter of vessel lumina 100–200 μm; 47: 5–20 vessels per square millimetre.
Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 69: fibres thin- to thick-walled.
Axial parenchyma: 75: axial parenchyma absent or extremely rare; 89: axial parenchyma in marginal or in seemingly marginal bands; 92: four (3–4) cells per parenchyma strand.
Rays: 98: larger rays commonly 4- to 10-seriate; 102: ray height > 1 mm; 103: rays of two distinct sizes; 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: 131: intercellular canals of traumatic origin.
Mineral inclusions: 136: prismatic crystals present; 137: prismatic crystals in upright and/or square ray cells; 154: more than one crystal of about the same size per cell or chamber.

(E.A. Obeng, P.E. Gasson & E.A. Wheeler)

Growth and development

Trees flower from October to March.

Ecology

Sloanea rhodantha occurs in dense, humid primary forest at (300–)400–2000 m altitude. It is most common in mid-elevation forest at 800–1200 m altitude.

Management

Sloanea rhodantha is locally common; up to 650 trees with a bole diameter of more than 10 cm have been recorded per ha. However, in general natural regeneration is rated as quite poor.

Genetic resources

Sloanea rhodantha is quite widespread in Madagascar and locally common. However, the on-going fragmentation of forest may make it liable to genetic erosion in the future because it is characteristic for undisturbed forest.

Prospects

Research on propagation and silviculture is recommended to ensure sustainable management in the future for this locally important but relatively poorly known species.

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.

Cao, S., Ranarivelo, L., Ratsimbason, M., Randrianasolo, S., Ratovoson, F., Andrianjafy, M. & Kingston, D.G., 2006. Antiplasmodial activity of compounds from Sloanea rhodantha (Baker) Capuron var. rhodantha form the Madagascar rain forest. Planta Medica 72(15): 1438–1440.

Guéneau, P., Bedel, J. & Thiel, J., 1970–1975. Bois et essences malgaches. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 150 pp.

Guéneau, P. & Guéneau, D., 1969. Propriétés physiques et mécaniques des bois malgaches. Cahiers scientifiques No 2, Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 51 pp.

Sallenave, P., 1971. Propriétés physiques et mécaniques des bois tropicaux. Deuxième supplément. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 128 pp.

Schatz, G.E., 2001. Generic tree flora of Madagascar. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 477 pp.

Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.

Tirel, C., 1985. Elaeocarpaceae. Flore de Madagascar et des Comores, famille 125. Muséum National d’Histoire Naturelle, Paris, France. 53 pp.

Wiselius, S.I. & Sosef, M.S.M., 1998. Sloanea L. 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. 527–529.

Other references

Boiteau, P., Boiteau, M. & Allorge-Boiteau, L., 1999. Dictionnaire des noms malgaches de végétaux. 4 Volumes + Index des noms scientifiques avec leurs équivalents malgaches. Editions Alzieu, Grenoble, France.

Brown, K.A., Ingram, J.C., Flynn, D.F.B., Razafindrazaka, R. & Jeannoda, V., 2009. Protected area safeguard tree and shrub communities from degradation and invasion: a case study in eastern Madagascar. Environmental Management 44: 136–148

Capuron, R., 1966. Etudes sur les essences forestières de Madagascar: Sloanea rhodantha (Baker) Capuron, Elaecarpaceae, voanana. Centre Technique Forestier Tropical, Antananarivo, Madagascar. 7 pp.

Coode, M.J.E., 1983. A conspectus of Sloanea (Elaeocarpaceae) in the Old World. Kew Bulletin 38(3): 347–427.

Decary, R., 1946. Plantes et animaux utiles de Madagascar. Annales du Musée Colonial de Marseille, 54e année, 6e série, 4e volume, 1er et dernier fascicule. 234 pp.

Guéneau, P., 1971. Bois de Madagascar. Possibilités d’emploi. Centre Technique Forestier Tropical, Antananarivo, Madagascar. 75 pp.

Guéneau, P., 1971. Bois et essences malgaches. Bulletin de Madagascar 305–306: 777–819.

Guéneau, P., 1972. Bois et essences malgaches. Bulletin de Madagascar 310: 235–277.

Miandrimanana, C., 2008. Description, distribution, écologie et risque d’extinction de quelques espèces endémiques de Madagascar dans la famille des Elaeocarpaceae. Mémoire de D.E.A., Faculté des Sciences, Université d’Antananarivo, Madagascar. 98 pp.

Sources of illustration

Tirel, C., 1985. Elaeocarpaceae. Flore de Madagascar et des Comores, famille 125. Muséum National d’Histoire Naturelle, Paris, France. 53 pp.

Author(s)

S. Rakotonandrasana, Centre National d’Application des Recherches Pharmaceutiques, B.P. 702, 101 Antananarivo, Madagascar

Correct citation of this article

Rakotonandrasana, S., 2012. Sloanea rhodantha (Baker) Capuron. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 17 September 2026.

See the Prota4U database.