Common name: African blackwood

African Blackwood originates in dry parts of tropical and subtropical Africa, with a natural range extending from Senegal to South Sudan and from Ethiopia through Kenya to southern Africa. 

It is either a multi-trunked shrub or a single-trunked tree 5 to 10 m (16 to 33 ft) tall, occasionally reaching up to 12 m (40 ft) under optimal conditions and develops an irregular or rounded crown of short, twisted branches armed with sharp spines. The bark is pale grey to yellow-brown, smooth on young trees, and becomes flaky with age. 

The leaves are feathery, comprised of up to twelve dull green, blunt oval leaflets arranged in near opposite pairs along the length. These fall to the ground in the dry season, leaving the branches bare until new growth returns in the rainy season.

The flowers are small, white, sweetly fragrant and held in branched clusters arising at nodules along the branches. They come into bloom at the start of the rainy season, coinciding with new leaf growth. They are soon followed by thin, papery seedpods up to 7 cm (2.8 in) long, turning grey at maturity, about six to eight months after flowering.

Material uses

African Blackwood produces a dense timber highly prized for its rich colour, though it can be highly variable in form and is very slow-growing, needing seventy years or more to reach timber-harvesting size.

Timber and lumber - It is a heavy wood, averaging around 1,200 kg per cubic metre (75 lb per cubic ft), which makes it durable and suitable for all types of construction. The heartwood is dark purple-brown with black streaks, contrasting strongly with the creamy-yellow sapwood.

Decay- and rot-resistant wood - The wood also has high natural resistance to rot, decay, and wood-boring insects. However, the logs are small in diameter, yielding only a limited amount of small planks. 

Carved craft - The almost black heartwood is highly prized in carving.

Wood craft - Also prized for general woodcraft.

​Musical instruments - Particularly for making musical instruments, including piano keys and woodwind instruments such as clarinets and flutes.​

Wood turning - Also valued for turnery.

Environmental uses

Species conservation - Threatened by over-harvesting for its wood, African Blackwood needs conservation and has been recorded as a near-threatened species by the International Union for Conservation of Nature (IUCN). Cultivating it in home gardens and on farms can help ease pressure on dwindling wild populations.​

Bust carved from African Blackwood

Climate

Grows naturally in sub-humid subtropical and tropical lowland to mid-elevation climates, generally grassland or savanna areas with annual lows of 17 to 24°C, annual highs of 28 to 37°C, annual rainfall of 700 to 1200 mm, and a dry season of 4 to 8 months.

Growing

New plants are usually grown from suckers, cuttings, or seed, which germinate readily but remain viable for only a few months. 

Performs best on free-draining clay, loam, sand, or stony soil of a moderately acid to neutral nature, generally with a pH of 5.5 to 7.5, and in full sun.

The roots are far-reaching and can fix nitrogen from the air in the soil, allowing it to thrive on nutrient-poor soils and withstand long periods of drought.

Problem features

Natural regeneration is by root suckers and seed, which are designed for wind dispersal and germinate readily. It is introduced in Australia, India, and other countries, and the Hawaii Pacific Weed Risk Assessment (HPWRA) project assesses it as a high weed-risk species for Hawaii.

Exposure to sawdust can cause allergic dermatitis in some people.

Books

• C.A.B. International 2013, The CABI encyclopedia of forest trees, CABI Publishing, Wallingford, Oxfordshire

• Chudnoff, M. 1984, Tropical timbers of the world, Forest Service, U.S. Department of Agriculture (USDA), Washington, D.C.

• Dharani, N. 2011, Field guide to common trees & shrubs of East Africa, 2nd ed., Struik Nature Publishing, Cape Town

• Hines, D. A., & Eckman, K. 1993, Indigenous multipurpose trees of Tanzania: uses and economic benefits for people, Cultural Survival Canada

• Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (eds). PROTA, Plant Resources of Tropical Africa, Volume 7(1) : Timbers 1, PROTA Foundation, Backhuys Publishers, Leiden

• National Research Council (Board on Science and Technology for International Development) 1979, Tropical legumes : resources for the future, The National Academies Press, Washington D. C.

• Porter, T. 2012, Wood : identification & use, Compact edition, Guild of Master Craftsman Publications, Lewes, East Sussex

• Randall, R. P. 2002, A global compendium of weeds, R.G. and F.J. Richardson Press, Melbourne

• Scheffer, T. C & Morrell, J. J. 1998, Natural durability of wood : a worldwide checklist of species, Forest Research Laboratory, Oregon State University, Corvallis, Oregon

• Tatken, R. L., & C. A. Browning 1987, Health effects of exposure to wood dust: A summary of the literature. No. PB-87-218251/XAB, National Institute for Occupational Safety and Health, Cincinnati, Ohio