Common Name: African Locust Bean

General Information

African locust bean is a deciduous tree with a dense, wide, spreading and umbrella-shaped crown consisting of heavy branches; it can grow from 7 - 20 metres, with exceptional specimens to 30 metres[]. The usually straight and cylindrical bole is often short, with branches produced low down; it can be up to 130cm in diameter. A taproot is often present, with lateral roots spreading up to 10 metres, occasionally 20 metres, from the bole[, ].
African locust bean is a very important, multi-purpose tree, it is commonly gathered from the wild for local use as food, medicine and to provide a wide range of commodities. The tree is often planted in and around villages for its many uses, whilst it has also become widely planted in Agroforestry systems throughout the tropics, where it provides shade and shelter for the other crops[].

Known Hazards

The bark and pods contain substances toxic to fish - the alkaloid parkine that occurs in the pods and bark may be responsible[].

Botanical References

Range

Western central and northeastern tropical Africa.

Habitat

Particularly found on areas such as farm woodland which are subject to semi-permanent cultivation, also open woodlands on savannahs, rocky slopes, stony ridges etc[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	15.00 m
Growth Rate	Medium
Pollinators	Bats, Bees, Insects
Cultivation Status	Cultivated, Semi-cultivated, Wild

Cultivation Details

Adapted to a wide ecological range, African locust bean is found naturally in the drier lowland tropics at elevations below 600 metres[]. It grows best in areas where annual daytime temperatures are within the range 28 - 40°c, but can tolerate 8 - 44°c[]. It prefers a mean annual rainfall in the range mm, but tolerates mm[]. It prefers a strongly seasonal climate with a dry season of 4 - 8 months[, ].
Grows best in a sunny position[]. Prefers well-drained, deep, sandy to loamy cultivated soils, but it is also found on shallow, skeletal soils and thick laterites[, ]. Prefers a pH in the range 4.5 - 5.5, tolerating 4 - 6[]. The plant has a deep taproot system and an ability to restrict transpiration, this gives it the capacity to withstand drought conditions once it is established[].
Young trees have a slow rate of growth[]. Growth is comparatively fast: seedlings may reach a height of 1 metre within the first year, and young trees of superior provenances can reach 7 metres tall in 6-year-old plantations[].
Trees start flowering at 5 - 7 years while still comparatively small. They reach their maximum height after 30 - 50 years, and can reach an age of 100 years[].
Trees in some areas have two flowering periods each year[].
The tree produces root suckers[].
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[].

Edible Uses

The pods contain a sweet, yellow, farinaceous pulp surrounding the seeds[, ]. This pulp can be eaten fresh or made into sweetmeats and drinks[, , ]. It contains up to 29% crude protein and up to 60% saccharose, is rich in vitamin C and high in oil content[, ]. The pulp also yields a flour that is much used in parts of Africa[, ]. The pink brown to dark brown pods are about 45cm long and 2cm wide[].

Seeds are fermented to make dawadawa, a black, strong-smelling, tasty food high in protein. Dried fermented seeds keep for more than a year in traditional earthenware pots without refrigeration, and small amounts are crumbled during cooking into traditional soups and stews that are usually eaten with sorghum- or millet-based dumplings and porridges. Because of the savoury taste and the high protein and fat values of the seed, it is sometimes described as a meat or cheese substitute, but it is not usually eaten in large amounts. Dawadawa is rich in protein, lipids and vitamin B2. Parinari curatellifolia is deficient in the amino acids methionine, cystine and tryptophan, but fermented beans are rich in lysine. The fat in the beans is nutritionally useful (approximately 60% is unsaturated)[, ].
The seeds contain antinutritional factors and have to be processed before use as food. Boiled and fermented seeds contain 35% proteins, 29% lipids, 16% carbohydrates and have good organoleptic properties and a positive effect on intestinal flora[].
A coffee substitute is prepared from the parched seeds[, , ]. The seeds are roasted and ground into a powder for use as a coffee substitute[].

Young pods are sometimes roasted on embers and eaten[].

Leaves are edible but not commonly eaten[]. They are sometimes eaten as a vegetable, usually after boiling and then mixed with other foods such as cereal flour[].

Young flower buds are added to mixed salads[].

Medicinal

The bark is used as a mouthwash, vapour inhalant for toothache, or for ear complaints. It is macerated in baths for leprosy and used for bronchitis, pneumonia, skin infections, sores, ulcers, bilharzia, washes for fever, malaria, diarrhoea, violent colic and vomiting, sterility, venereal diseases, guinea worm, oedema and rickets, and as a poison antidote[].

Leaves are used in lotions for sore eyes, burns, haemorrhoids and toothache[].

Seed is taken for tension, and pulp for fevers, as a diuretic and as a mild purgative[].

Roots are used in a lotion for sore eyes[].

An alcoholic extract of crude seeds showed anti-hypertensive activity and contractile effect on smooth muscles of the intestine, and increased the tonus and mobility of the uterus[].
Ichthyotoxic and molluscicidal activities have been recorded for the seeds due to the presence of saponins[].
The bark, leaves and pod husks are rich in tannins, which in general have anti-diarrhoeal activities[].
Analgesic and anti-inflammatory activities have been demonstrated for the bark extracts[].
The aglycone flavonoids in the leaves have spasmolytic activity on smooth muscles, and also vasodilatory and antiseptic effects[].
Coumarin derivatives in leaf extracts have anticoagulant activity[].

Agroforestry Uses:

A useful windbreak and shade tree[]. Soils under the tree are improved by its leaf fall[, ].
It is common practice to grow several crops such as maize, cassava, yams, sorghum and millet under the canopy[].

Other Uses

Pods and roots contain fibres and are used as sponges and as strings for musical instruments[, ].

Twigs are used to clean the teeth. The bark stains the mouth red and also contains saponins that clean the teeth[].

A mucilage obtained from part of the fruit is made into a fluid and used for hardening earth floors and to give a black glaze in pottery[].

The fruit pods are used to produce an insecticide powder, which is added to water and sprayed on crops[].

The husks of pods, mixed with indigo, improve the lustre of dye products[].
The boiled pods are used to dye pottery black[]. The ash is applied as a mordant[].

The seeds and bark are a source of tannins[, ].

The wood ashes are used as a source of potash in making soap and indigo dye[].

Wood is whitish, moderately heavy, 580-640 kg/cubic m when air seasoned, relatively hard and solid; it smells unpleasant when newly felled, but seasoning does not take long and only occasionally causes shape distortion; easily worked by hand or power tools; nails, glues, varnishes and paints well; mainly useful as a light structural timber, for example, for vehicle bodies, agricultural implements, boxes, crates and barrels, furniture, mortars and pestles, bowls, planks and carvings[, ].
The branches are sometimes lopped for firewood[, ].

Propagation

Seed - it has a hard seedcoat and benefits from scarification before sowing in order to speed up and improve germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing. The plant forms two different types of seed in each pod, reddish-dark ones and black ones[]. The reddish dark have thinner seed coats and germinate more easily and quickly, even without scarification[]. Young plants quickly form a deep taproot so it is best to sow the seed in individual, deep containers. Usually about 75% of all the seeds will germinate[]. Seedlings can be ready to plant in their permanent positions when they are 10 - 14 weeks old[].
Cuttings of mature wood[].
Grafting.

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