Prota 7(1): Timbers/Bois d’œuvre 1
Bull. Mens. Soc. Linn. Paris 1: 436 (1884).
Papilionaceae (Leguminosae - Papilionoideae, Fabaceae)
Origin and geographic distribution
Dalbergia purpurascens is endemic to Madagascar, where it occurs widespread though scattered in the northern, western and south-central parts.
The wood is used for cabinet making and carpentry. It is one of the so-called rosewoods (‘Madagascar rosewood’, ‘palisander’). It is locally used for carving and has been used for railway sleepers. Fresh wood chips are used in dyeing baths.
Production and international trade
The wood is traded in small amounts in local and international markets, often mixed with the wood of other Dalbergia spp.
The heartwood is dark-coloured, attractive and of high quality. In a screening test for insecticidal leginsulin-like peptides, Dalbergia purpurascens tested negatively.
Deciduous small to medium-sized tree up to 25 m tall; young branches glabrous or short-hairy. Leaves arranged spirally, imparipinnately compound with (11–)13–25(–33) leaflets; stipules small, caducous; petiole and rachis sparsely hairy or glabrous; petiolules 2–3 mm long; leaflets alternate, elliptical to oblong, (1.5–)2–5 cm × (0.5–)1–2.5 cm, papery, glabrous or sparsely hairy. Inflorescence a terminal panicle 6–15 cm long, with short and slightly coiled final divisions, short-hairy. Flowers bisexual, papilionaceous, 4–5.5 mm long; pedicel 0.5–1 mm long; calyx campanulate, 2.5–3 mm long, lobes shorter than tube, upper lobes fused; corolla whitish, with broadly obovate to violin-shaped standard and clawed wings and keel; stamens 10, fused into a tube, but free in upper part; ovary superior, densely short-hairy, with distinct stipe at base, style c. 0.5 mm long. Fruit a flat, elliptical to obovate or oblong pod 3–9 cm × 1–3 cm, with stipe 2–4 mm long, glabrous, blackish, indistinctly reticulately veined, indehiscent, 1–2(–3)-seeded. Seeds kidney-shaped, 7–8 mm × 4–5 mm, reddish brown.
The growth of Dalbergia purpurascens trees is slow, with 7-year-old trees being 1–5 m tall. Flowering is from January to March. The roots have nodules containing nitrogen-fixing bacteria; Bradyrhizobium and Mesorhizobium strains have been isolated from the root nodules.
Dalbergia is a large pantropical genus comprising about 250 species. Tropical Asia and tropical America have about 70 species each, continental Africa about 50 and Madagascar slightly over 40. In Madagascar many Dalbergia species produce high-quality wood. Dalbergia lemurica Bosser & R.Rabev. from western Madagascar resembles Dalbergia purpurascens, but differs in its shorter leaves and smaller leaflets (up to 1.5 cm long). The reddish wood of Dalbergia lemurica is used for cabinet making and joinery. The species has been included in the IUCN Red list as vulnerable.
Dalbergia purpurascens occurs in deciduous, seasonally dry forest and woodland, up to 1000 m altitude, on sandy, limestone-derived and rocky soils.
Dalbergia purpurascens can be propagated by seed. To obtain seed, the fruits are harvested as they turn dark brown and they are dried in the sun. The seeds are extracted manually and dried in the sun for 2 days, after which they are sown. The germination rate is 40–80%. Pre-sowing treatment of the seeds may be necessary for homogenous germination. The seedlings are pricked out into pots and stay in the nursery for about one year until they are about 50 cm tall.
Genetic resources and breeding
Although Dalbergia purpurascens is widespread in Madagascar and some protected areas are located within its area of distribution, it is selectively felled for its valued timber and populations have been reduced seriously. It has been included in the IUCN Red list as vulnerable.
Very little information is available on Dalbergia purpurascens, and much research is still needed to judge its prospects as a timber tree of future importance. In view of its superior wood qualities, planting experiments seem worthwhile. Its declining numbers warrant protection of the remaining stands.
• 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.
• du Puy, D.J., Labat, J.N., Rabevohitra, R., Villiers, J.-F., Bosser, J. & Moat, J., 2002. The Leguminosae of Madagascar. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 750 pp.
• Randrianasolo, J., Rakotovao, P., Deleporte, P., Rarivoson, C., Sorg, J.-P. & Rohner, U., 1996. Local tree species in the tree nursery. In: Ganzhorn, J.U. & Sorg, J.P. (Editors). Ecology and economy of a tropical dry forest in Madagascar. Primate Report 46–1. German Primate Center, Göttingen, Germany. pp. 117–132.
• du Puy, D., 1998. Dalbergia purpurascens. In: IUCN. 2006 Red list of threatened species. [Internet] http://www.iucnredlist.org. Accessed December 2006.
• Louis, S., Delobel, B., Gressent, F., Duport, G., Diol, O., Rahioui, I., Charles, H., & Rahbe, Y., 2007. Broad screening of the legume family for variability in seed insecticidal activities and for the occurrence of the A1b-like knottin peptide entomotoxins. Phytochemistry 68(4): 521–535.
• Rasolomampianina, R., Bailly, X., Fetiarison, R., Rabevohitra, R., Béna, G., Ramaroson, L., Raherimandimby, M., Moulin, L., de Lajudie, P., Dreyfus, B. & Avarre, J .-C., 2005. Nitrogen fixing nodules from rose wood legume trees (Dalbergia spp.) endemic to Madagascar host seven different genera belonging to α- and β-proteobacteria. Molecular Ecology 14(13): 4135–4146.
Correct citation of this article:
Lemmens, R.H.M.J., 2008. Dalbergia purpurascens Baill. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.