African Oil Bean. Oil Bean Tree, Owala Oil
Pentaclethra macrophylla

Family: Fabaceae

What it is like

Pentaclethra macrophylla is an evergreen Tree growing to 30 m (98ft) by 30 m (98ft) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 10. The flowers are pollinated by Bees. It can fix Nitrogen. Suitable for: medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid and neutral soils and can grow in very acid soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.

Height (m): 30

Where it is found

Mainly in lowland rainforest, but also sometimes in the high forest zone. Often occurs near streams and on the edges of damp depressions, and is frequently seen as a small tree of untidy habit and large crown on roadsides and farms.

West tropical Africa - Senegal to Central African Republic, south to Angola and the Congo.

Conservation Status: This taxon has not yet been assessed

Countries/locations it is found in

Africa, Angola, Benin, Cameroon, Central Africa, Central African Republic, CAR, Congo DR, Congo R, Côte d'Ivoire, Equatorial-Guinea, Gabon, Gambia, Ghana, Guinea, Guinée, Guinea-Bissau, Ivory Coast, Liberia, Niger, Nigeria, Sao Tome and Principe, Senegal, Sierra Leone, Sudan, Togo, West Africa

How it is used

Food

Rating: 3

Seeds - boiled or roasted. They can be ground into a flour and used in making bread. The pods are 40 - 50cm long and 5 - 10cm wide, containing 6 - 10 flat, glossy brown seeds up to 7cm long. The seeds are fermented to produce 'ugba'. They are boiled for 3 - 12 hours; then the seedcoat is removed. When the cotyledons are cooled to room temperature they are sliced into small pieces of 4 - 5 cm × 1 - 2 mm and washed with water. The slices are boiled for 1 - 2 hours, cooled and soaked in water for 10 hours. Then the slices are drained in a basket lined with banana leaves. The drained slices are wrapped in blanched leaves of banana or Mallotus oppositifolius and incubated at ambient temperature for 4 - 6 days when prepared for use as a snack or sidedish, or for 7 - 10 days when prepared as a condiment for soups. The fermentation is proteolytic and proceeds under alkaline conditions. It is caused mainly by Bacillus subtilis, but other Bacillus spp. are also involved, while other bacteria may be present as contaminants. The seeds contain 30 - 36% of an edible oil. They are used for the production of 'owala-oil', or 'owala-butter' which is used in food. The ash of the seedpods is used as a salt substitute.

Oil: Oil

Seed: includes nuts, cereals, peas and beans.

Seedpod: things such as Okra, French and Runner beans.

Salt: plants that provide a substitute for salt.

Medicine

Rating: 2

Extracts of the leaf, stembark, seed and fruit pulp have anti-inflammatory and anthelmintic activity, and are used to treat gonorrhoea and convulsions, and also used as analgesic. The crushed seeds are taken to acquire an abortion. Leaf and stem decoctions are taken against diarrhoea. A lotion made from the bark is used as a wash on sores. The ripe fruits are applied externally to heal wounds. The root bark is used as a laxative, as an enema against dysentery and as a liniment against itch. An infusion of the bark is used as an abortifacient.

Abortifacient: Causes an abortion.

Analgesic: Relieves pain.

Anthelmintic: Expels parasites from the gut.

Antidiarrhoeal: Provides symptomatic relief for diarrhoea. Also see Astringent.

Antiinflammatory: Reduces inflammation of joints, injuries etc.

Dysentery: Used in treating dysentery - an infection of the intestines that causes diarrhoea containing blood or mucus.

Laxative: Stimulates bowel movements in a fairly gentle manner.

Skin: Plants used in miscellaneous treatments for the skin.

Other

Rating: 3

Agroforestry Uses: Farmers protect this species on farms because of its open crown form that allows substantial light and does not inhibit crop plants grown under its canopy. This accounts for the trees use in combination with food crops on farms and particularly in home gardens in south east Nigeria. The tree produces a heavy leaf fall and these are used as a mulch. Other Uses: The seeds contain 30 - 36% oil. They are used for the production of 'owala-oil', or 'owala-butter' which is used in soap and candle production. The dried pods are used as fuel. The ashes of burnt pods are used as a mordant. The seeds are decorative and are used as beads in necklaces and rosaries. The heartwood is reddish brown and not always distinctly demarcated from the whitish or grey sapwood. The wood is hard, the grain interlocked and difficult to work. Wood of suitable size can be difficult to find but, when available, it is used for turnery, wheelwright's work, fencing, railway sleepers and general carpentry. Traditionally, it is used to make pestles and mortars. The wood is used as firewood and charcoal. Pentaclethra macrophylla nodulates and fixes atmospheric nitrogen.

Beads: Used as necklaces etc.

Charcoal: Used for fuel, drawing, deodorant, filter, fertilizer etc.

Fencing: Plants that can be used for fencing.

Fuel: Usually wood, plant materials that have been mentioned as being a good fuel.

Lighting: Plants that can be used as torches etc. See also Oil and Wax.

Mordant: Used for making a dye more permanent, it also affects the colour of the dye.

Mulch: Used for covering the ground to conserve the nutrients in the soil.

Oil: Vegetable oils have many uses, as lubricants, lighting, soap and paint making, waterproofing etc. This does not include the edible oils unless they are also mentioned as having other uses.

Soap making: Plants used as an ingredient in making soaps. Does not include the essential oils, dyes and oils that are also used in making soap.

Soil conditioner: Plants grown to improve the structure of the soil. See also Green manures.

Wood: A list of the trees and shrubs that are noted for having useful wood.

Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.

Staple Crop: Protein-oil: (16+ percent protein, 16+ percent oil). Annuals include soybeans, peanuts, sunflower seeds. Perennials include seeds, beans, nuts, and fruits such as almond, Brazil nut, pistachio, walnut, hazel, and safou.

Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.

Staple Crop: Protein-oil: (16+ percent protein, 16+ percent oil). Annuals include soybeans, peanuts, sunflower seeds. Perennials include seeds, beans, nuts, and fruits such as almond, Brazil nut, pistachio, walnut, hazel, and safou.

Carbon Farming: Plants that can be a critical part of the solution to climate problems. The Carbon Farming Solution - Eric Toensmeier.

Coppice: A traditional method of woodland management which exploits the capacity of many species of trees to put out new shoots from their stump or roots if cut down.

Food Forest: Plants for Edible Forest Gardens and Food Forests.

Nitrogen Fixer: Plants that fix nitrogen in the soil

How it is grown

A plant of the humid and subhumid tropics. It grows best in areas where the mean annual temperature is within the range 24 - 30°c, but can tolerate 18 - 34°c. It prefers a mean annual rainfall in the range 1,800 - 2,200mm, tolerating 1,000 - 2,700mm. Succeeds in full sun and in light shade. Prefers a deep, moderately fertile medium soil. Tolerant of some water-logging. Prefers a pH in the range 4.5 - 5.5, but tolerates 4 - 6.5. Seedling trees can reach a height of 1.5 metres by the end of their first year. The trees start to produce beans from their tenth year and will continue to bear regularly. After about 2-years growth in the forest, the trees become relatively fire resistant and resprout readily when lopped. Trees coppice well and often produce watershoots around their base. There are conflicting reports on whether or not this tree has a symbiotic relationship with certain soil bacteria, so it is unclear as to whether this tree fixes atmospheric nitrogen.

Propagating it: Seed - best sown as soon as it is ripe because it has a short viability. Storage at 15°c can extend longevity for about three months. Scarifying the seed and then soaking for 24 hours in warm water prior to sowing increases the germination rate and reduces the time taken to germinate. About 87% of treated seed germinates within 14 - 16 days. Adult trees can be air layered. Cuttings of juvenile plants can be rooted, but usually require rooting hormone.

Best place to grow:

Habit: Tree

Hardiness: 10-12

Growth: Fast

Soil: Medium, heavy (clay)

Shade: Semi-shade, no shade

Moisture: Moist

Things to keep in mind

The seeds contain a toxic alkaloid. They are pulverized and used as a component of an arrow poison, they are also used as fish poison and as mild drug (snuff).

Its other names

Local names

African oil bean, An-fal, Apara, Arvore-das-mares, Ataa, Atawa, Atta Bean, Bemba, Benguele, Bgangban, Biague, Bobala, Bowala, Cheboe, Cherbou, Congo acacia, Coquenguer, Ebaye, Ebe, Essiri, Fa-wuli, Faa, Fakha, Fawei, Gbau, Kombolo, Marrone, Mbalaka, Mubala, N'tantass, Nganzi, Okpagha, Opachalo, Otshakula, Ovala, Owala oil tree, Pao-di-godre, Sindjam-djane, Sucupira, Uaua, Ugba, Ukana, Ukelede, arbre à semelles, acacia du Congo (Fr).

Synonyms

No synonyms are recorded for this name.