Millettia grandis (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Medicinal
Timber
Fuel
Ornamental
Forage / feed

Millettia grandis (E.Mey.) Skeels

Protologue: U.S. Dept. Agric. Bur. Pl. Ind. Bull. 248: 55 (1912).

Family: Papilionaceae (Leguminosae - Papilionoideae, Fabaceae)

Synonyms

• Millettia caffra Meisn. (1843).

Vernacular names

• Umzimbeet, Kaffir ironwood (En).
• Songa (Po).

Origin and geographic distribution

Millettia grandis occurs from southern Mozambique to eastern South Africa. It has been planted occasionally outside this region, e.g. in Mauritius.

Uses

The wood is locally important for building poles, durable furniture, carving and implements such as walking sticks. It is suitable for heavy construction, heavy flooring, joinery, mine props, shipbuilding, vehicle bodies, furniture, cabinet work, implements, sporting goods, musical instruments, toys, novelties and turnery. It is valued as firewood. Millettia grandis is planted as an ornamental shade and wayside tree. It can also be used as a windbreak along pastures. Powdered seed is taken as an anthelmintic. Ground roots serve as a tranquilizer and to induce sleep. The roots have also been used as fish and arrow poison.

Properties

The heartwood is dark brown and distinctly demarcated from the yellowish sapwood. The grain is straight, texture fine. The wood has an oily surface.

The wood is very heavy and hard. The density is about 1140 kg/m³ at 12% moisture content. The wood should be dried slowly and with care to avoid serious checking. At 12% moisture content, the modulus of rupture is about 182 N/mm², modulus of elasticity 19,200 N/mm², compression parallel to grain 68 N/mm², shear 16 N/mm², Janka side hardness 15,350 N and Janka end hardness 14,100 N.

Considerable power is required in sawing and planing, but a good polish can be obtained. The wood is easy to split. It holds nails and screws well, but pre-boring is needed. It is very durable and resistant to insect attack. The heartwood does not absorb preservatives.

Description

• Evergreen or deciduous shrub or small tree up to 13(–25) m tall; bark surface smooth to flaky, grey to pale brown; twigs slightly hairy or glabrous.
• Leaves alternate, imparipinnately compound with 4–7 pairs of leaflets; stipules absent; petiole and rachis together 10–20 cm long; stipels needle-shaped, 4–6 mm long; petiolules c. 4 mm long; leaflets opposite, oblong to lanceolate, 4–8 cm × 1–3.5 cm, acuminate at apex, glabrous above, short-hairy below.
• Inflorescence a terminal, spike-like panicle up to 25 cm long, with short branches, dark brown velvety hairy.
• Flowers bisexual, papilionaceous; pedicel 2–6 mm long, with 2 small bracteoles near apex; calyx campanulate, c. 7 mm long, tube about as long as lobes; corolla pale purple, standard orbicular, c. 15 mm in diameter, with claw at base, wings and keel slightly shorter; stamens 10, 9 fused, 1 almost free; ovary superior, hairy, style slender, curved, hairy at base.
• Fruit an oblong to lanceolate, flat pod up to 15 cm × 3.5 cm, with stiff wall, densely brownish hairy, dehiscent with spiralling valves, often 2-seeded.
• Seeds oblong, flattened, smooth, reddish brown.

Other botanical information

Young trees grow fairly fast: 80–100 cm/year under favourable conditions. New foliage of Millettia grandis is dark reddish brown or coppery red. Trees flower in December–January. The fruits ripen 6–8 months later. Millettia grandis nodulates with rhizobial bacteria.

Millettia comprises about 150 species, most of them (about 90) in mainland Africa, 8 endemic to Madagascar, and about 50 in tropical Asia. It is in need of revision and should be split into several genera based on molecular evidence.

Ecology

Millettia grandis occurs in coastal forest and open lowland forest up to 600 m altitude. It can be found as a pioneer along forest margins. It tolerates light frost. It often occurs on sandy soils, but also on shale, where trees are often gnarled. It grows best in deep soils where ample water is available. It is locally common.

Management

Fresh seed is used for propagation; soaking in hot water for one night improves germination. Young trees transplant well. Larvae of the butterfly Deudorix diocles are commonly found in the pods. Baboons strip off and eat the bark.

Genetic resources

Millettia grandis has a rather small area of distribution. Therefore, it may easily become liable to genetic erosion, although it is still locally common. In many regions it is already under pressure because it is a favoured tree for building poles and wood carving and because many forests in its area of distribution are being cleared for agricultural land. However, it seems that Millettia grandis could sustain current levels of exploitation in some forests in South Africa.

Prospects

To meet expected demands and relieve the pressure on natural populations of Millettia grandis, starting planting programmes is recommended. These seem to have good prospects because the trees can be easily propagated by seed and grow fairly fast, so that harvesting of poles for construction and wood for the carving industry can be expected within a reasonable period. Millettia grandis also has prospects as an ornamental tree for gardens and streets and for windbreaks in agroforestry systems.

Major references

• Baloyi, K.J. & Reynolds, Y., 2004. Millettia grandis. [Internet] South African National Biodiversity Institute, Cape Town, South Africa. http://www.plantzafrica.com/ plantklm/ milletgrand.htm May 2007.

• 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.

• Coates Palgrave, K., 1983. Trees of southern Africa. 2nd Edition. Struik Publishers, Cape Town, South Africa. 959 pp.

• Palmer, E. & Pitman, N., 1972–1974. Trees of southern Africa, covering all known indigenous species in the Republic of South Africa, South-West Africa, Botswana, Lesotho and Swaziland. 3 volumes. Balkema, Cape Town, South Africa. 2235 pp.

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

Other references

• Corby, H.D.L., 1988. Types of rhizobial nodules and their distribution among the Leguminosae. Kirkia 13(1): 53–123.

• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.

• Obiri, J., Lawes, M. & Mukolwe, M., 2002. The dynamics and sustainable use of high-value tree species of the coastal Pondoland forests of Eastern Cape Province, South Africa. Forest Ecology and Management 166(1/3): 131–148.

• van Wyk, B.E. & Gericke, N., 2000. People’s plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria, South Africa. 351 pp.

• van Wyk, B. & van Wyk, P., 1997. Field guide to trees of southern Africa. Struik Publishers, Cape Town, South Africa. 536 pp.

Author(s)

• R.H.M.J. Lemmens, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Lemmens, R.H.M.J., 2008. Millettia grandis (E.Mey.) Skeels. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 18 December 2024.

• See the Prota4U database.