Hook., Niger Fl.: 463 (1849).
n = 20, 21, 2n = 40
Kigelia aethiopica Decne. (1845), Kigelia pinnata (Jacq.) DC. (1845).
Sausage tree, cucumber tree (En). Saucissonnier, faux baobab (Fr). Mvungunya, mwegea, mwicha, mranaa (Sw).
Origin and geographic distribution
Kigelia africana occurs throughout tropical Africa, particularly in the drier regions. It is also found in South Africa (Northern Provinces, Kwazulu-Natal) and Swaziland, but does not occur in Mauritania, Sγo Tomι and Principe, or the Indian Ocean islands. It has been introduced as an ornamental to Cape Verde and Madagascar, as well as to Iraq, Pakistan, India, China, South-East Asia, Australia, Hawaii and Central and South America.
Kigelia africana is widely used throughout Africa for a variety of purposes, particularly in local medicine, and more recently in commercial applications to treat various skin complaints.
The diversity of complaints against which the plant is used includes fainting, anaemia, sickle-cell anaemia, epilepsy, respiratory ailments, hepatic and cardiac disorders, and nutritional illnesses such as kwashiorkor, rickets, wasting and weakness. The leaves are sometimes used to prepare a general tonic for improved health and growth. Aqueous fruit preparations are applied as a wash or rub to promote weight gain in infants.
The roots, bark, leaves, stems, twigs and fruits are used to treat digestive disorders. Administration is typically by oral ingestion or as an enema. The roots, bark and ripe or unripe fruits are taken as a laxative or emetic, to treat chronic and acute digestive disorders and against gastric infections. Remedies containing the fruits of Kigelia africana and Capsicum or Anthocleista are taken internally to relieve constipation or haemorrhoids.
Infections of the genito-urinary tract, particularly venereal diseases, are treated both internally and externally with preparations of the roots, bark, leaves, stems and twigs. In West and Central Africa, palm wine, in which dried and ground bark is macerated, is taken against syphilis. Venereal diseases in children are treated simultaneously with a drink and wash prepared from decocted bark. A commercial product containing Kigelia africana stem bark is used to treat Candida albicans infections. In Cτte d'Ivoire, renal and bladder ailments are treated with medicaments containing the bark and leaves of Kigelia africana and several other medicinal plants.
Kigelia africana is widely used to treat gynaecological disorders. Aqueous preparations of the roots, fruits and flowers are administered orally or as a vaginal pessary. The fruits and bark are used to promote breast development in young women, or in contrast to reduce swelling and mastitis of the breasts. The fruits are further employed as a galactogogue. The bark and leaves are decocted and administered as an abortifacient.
Sexual complaints such as infertility, poor libido, sexual asthenia and impotence are treated with medicines containing the fruits, roots or leaves. A small amount of unripe fruit is chewed, or an aqueous preparation is taken orally as a sexual stimulant, and the intoxicating traditional beer to which they are added is drunk as an aphrodisiac. Excessive use of Kigelia africana to treat male sexual complaints is said to induce scrotal elephantiasis, although in some regions the fruits are used to remedy this condition.
Powders and infusions of the bark, leaves, stems, twigs or fruits are used to clean and dress flesh wounds and open sores. Many dressings, topical treatments and infusions containing Kigelia africana are also used for their analgesic and anti-inflammatory properties. The bark, stems, twigs, leaves and fruits are infused and taken orally, or applied locally, to relieve rheumatism, sprains, haematoma and bruising; a decoction of the fruit and bark is used to relieve toothache and headache. Snake bite antidotes are made with an infusion of the fruits, stems, leaves, twigs or bark, taken orally or rubbed onto the bite. A fruit decoction is used to treat oedema of the legs.
Kigelia africana is used to treat infectious diseases including leprosy, impetigo, and worm infestations in the blood. Dermal complaints and infections, such as whitlows, cysts, acne and boils, are treated with traditional medicines containing the fruits, and less frequently, the bark. Sore eyes are treated with drops made from flower sap mixed with water. Commercially manufactured products are used for symptomatic relief or cure of skin conditions including, among others, sunburn, chafing, psoriasis, itchy scalp and nappy rash. A broad-spectrum antimicrobial cream, reputedly effective against a number of common microbial infections, is produced from the stem bark. Fungal infestations such as ringworm, mycosia and athlete's foot are washed with the water in which bark has been macerated, and preparations containing the leaves and fruits applied locally. A root decoction is administered against internal parasitic infestations, notably tapeworm.
Kigelia africana is used in both traditional and orthodox medicines to treat malignant neoplasms such as skin melanoma, tumours and breast cancer. Traditional preparations include extracts, poultices and powders of the bark or fruits; topical creams containing extracts of the fruits are produced commercially.
The fruits, and sometimes other plant parts, are also much used in ethnoveterinary medicine to treat digestive system disorders, leg oedemas, dermal irritations and infections, mastitis and retained placenta. Brucellosis and Newcastle disease are also treated with Kigelia africana.
Kigelia africana provides a nutritious food source during times of famine: the hard seeds are roasted and eaten. The fruit pulp, however, is said to be inedible and toxic, may have intoxicant or purgative effects, and may cause blistering of the tongue and skin. However, fallen fruits along with leaves and flowers are browsed or foraged by livestock and game. Fruits and bark are in the brewing process to aid fermentation and enhance the flavour of traditional beers, often mixed in variable proportions with roots of Aloe spp.
The wood is considered excellent for dugout canoes, planks and fence-posts. It is also used for making boxes, drums, stools, yokes, tool handles, mortars and large bowls for watering cattle. Weapon bows are made from branches, and smaller branches are hollowed to administer enemas to children. Wood and fruits are carved into mousetraps, dolls, and various items of crockery and cutlery. The wood is used as fuel. A black dye is obtained from the tannin-rich fruit pulp.
Due to the unusual fruits and large flowers, Kigelia africana is considered a striking ornamental plant, and the fruits are used as florists' material. The thick stem is an attractive feature for bonsai. The tree is sometimes planted as a boundary marker, but usually at roadsides and for shade. Due to its occurrence along watercourses, it is suitable for erosion control and riverbank stabilisation.
Kigelia africana is regarded as sacred in many regions; religious meetings are held underneath the tree, and the flowers and fruits are regarded as fetish. Fruits are commonly sold in markets as charms to promote wealth and prosperity, to impart strength and courage on warriors prior to, to increase crop yields, and as a fetish for fecundity, or to avert whirlwinds.
Production and international trade
Kigelia africana is of subsistence value in most parts of Africa; the fruits and bark are collected and traded locally in market places. Commercial value is attributable to industrially produced pharmaceutical products, for which fruits are harvested from naturally occurring trees, and stem bark from young cultivated trees in Zimbabwe.
The use of Kigelia africana in traditional African medicines is in some cases verified by corresponding pharmacological properties. Of the phytochemicals elucidated in extracts of Kigelia africana, the compound groups to which activity is most frequently attributed are naphthoquinones and iridoids.
Extracts of the bark, wood, roots and fruits possess antibacterial and antifungal properties. These extracts exhibit significant inhibitory effects in vitro against common Gram-negative and Gram-positive bacteria, and the yeast Candida albicans. Of the naphthoquinones isolated in fruit and root extracts, kigelinone has shown notable antimicrobial activity. Iridoids and dihydroisocoumarins in extracts of the bark, fruits and roots may enhance the antimicrobial activity of naphthoquinones. Other active antimicrobial compounds present in the bark and are the phenylpropanoids caffeic acid, p-coumaric acid and ferulic acid. The naphthoquinones are responsible for the antiprotozoal activity of root bark against.
Kigelia africana is renowned for anti-cancer properties, and laboratory screening has confirmed in-vitro anti-cancer activity. Fruit extracts exhibited significant effects against induced tumours in mice. Fruit and bark extracts have shown moderate efficacy against melanotic cell lines. of dried fruit elicited lower cytotoxic responses than those of fresh fruit, indicating that the active principles may be thermolabile. The naphthoquinones lapachol and isopinnatal, in some extracts of bark, wood, fruits and roots, exhibit antineoplastic activity against melanoma cell lines. Sterols and iridoids are ubiquitous in the plant and may be a factor in the activity against melanoma. Naphthoquinones and sterols isolated in root extracts suggest anti-cancer potential, although in-vitro activity is not confirmed. The reported cytotoxicity of the root in the brine shrimp assay was attributed to the presence of γ-sitosterol.
The use of fruits for anti-inflammatory purposes is supported by effects against inflammation induced in rat paws. Cinnamic acid derivatives are thought to be responsible for anticonvulsant properties for which Kigelia africana is used to prevent epileptic fits.
The leaves and fruits contain flavonoids. A high concentration of flavonoids may be responsible for antidiarrhoeal properties, increased by antimicrobial constituents. In contrast to the use of Kigelia africana as a laxative, preliminary studies have shown a preventive effect of leaf extracts against diarrhoea in laboratory rats.
The bark and leaves are bitter tasting, and the bark is reported to contain a bitter principle. Acute toxicity tests of the fruits indicate they are non-toxic, although they are said to be very. Tannins present in the bark and fruit impart a dark, astringent dye. Sap from the fruits may temporarily stain the hands brown.
The wood is whitish or yellowish with pale brown to reddish-yellow heart, moderately heavy (about 720 kg/m³ at 15% moisture content), easy to work and takes a good polish. However, it is not of commercial value. Its energy value is 1517 MJ/kg.
Small to medium-sized, semi-deciduous tree, up to 25(35) m tall; trunk up to 60 cm in diameter, widely and low branching; bark grey, smooth or flaking; crown rounded. Leaves opposite or whorled, usually in whorls of 3, usually crowded towards the apex of branches, imparipinnate, up to 60 cm long; stipules absent; petiole up to 15 cm long, rachis up to 25(29) cm long; leaflets 513, lateral ones subopposite, subsessile except rounded to cuneate, more or less asymmetrical, apex rounded or retuse to broadly tapering, margin entire, serrate, toothed or wavy, papery to leathery, glabrous to more or less hairy at both surfaces, with (4)613 pairs of lateral veins. Inflorescence a terminal, pendulous, very lax panicle, up to 100(150) cm long, with long peduncle. Flowers bisexual, very large; pedicel up to 11(13.5) cm long, upcurved at tip; calyx shortly tubular to campanulate, 24.5 cm long, suddenly widening and incurving upwards, limb 2-lipped, the superior lip 2-lobed, the lower one 3-lobed and recurved, lobes rounded, at first yellowish, later becoming reddish to purplish with darker streaks; stamens 4, didynamous, adnate to the corolla tube, 47.5 cm long, staminode 1; disk annular, thick; ovary superior, 1-celled, up to 1.5 cm long, with 2 parietal placentas, style filiform, up to 7 cm long. Fruit a large, sausage-like, pendulous berry up to 100 cm Χ 18 cm and up to 12 kg in weight, with peduncle up to 100 cm long, indehiscent, wall woody, surface heavily marked by lenticels, grey-brown when mature, many-seeded. Seeds obovoid, ca. 10 mm Χ 7 mm, testa leathery, embedded in a fibrous pulp.
Other botanical information
Kigelia africana is extremely variable in habit and leaf morphology. This has led to the distinction of up to 10 separate species. Nowadays, it is generally accepted that Kigelia comprises a single polymorphous species. Despite the present recognition of only one species, synonyms are continually used in the literature. Specimens growing in the forest tend to have larger leaflets with more acute apices, entire margins and dense indumentum compared with specimens from the savanna. Recent studies maintain at least two sub-generic taxa in East Africa, occupying overlapping savanna- and forest vegetation types.
- Macroscopic characters:
Heartwood pale brown to reddish-yellow.
- Microscopic characters:
Growth rings usually indistinct. Vessels diffuse, ca. 11/mm², mostly solitary but also in irregular multiples of 23, with an average tangential diameter of 150 µm; perforation plates simple; intervessel pits with an average diameter of 8 µm; vessel-ray pits simple; tyloses sometimes present. Fibres sparse, thin- to thick-walled, non-septate, on average ca. 980 µm long, with distinctly bordered pits. Parenchyma exceptionally abundant, both as paratracheal and as banded parenchyma. Rays ca. 7/mm, but 4/mm also recorded, (2)34 cells wide, all ray cells procumbent although the marginal cells are somewhat shorter and slightly higher than the body ray cells; storied structure absent.
Growth and development
In warmer regions, the growth rate of young plants can exceed 1 m/year, and the tree will reach good shade proportions within 5 years. In colder climates, germination and vegetative growth are relatively slow.
The flowering period for a single tree continues for several months. Flowers open in the evening, and remain open for one night only. The corolla falls off within 2 days, leaving the persistent calyx, ovary and style. Pollination studies suggest that the most important pollination vectors are bats. However, unlike most bat-pollinated flowers which are characteristically white or cream, the flowers of Kigelia africana are reddish to purplish; the strong unpleasant odour is likely to be the primary attractant.
Fruits may remain on the tree for up to 6 months. Seed is released only on decay of the fallen woody fruits, or dispersed when eaten by game and livestock. Elephant and rhinoceros are reported as seed distributors.
Kigelia africana occurs along watercourses, in riverine fringes, alluvial and open woodland, high-rainfall savanna, shrubland, and in rain forest. It occurs on loamy red clay soils, sometimes rocky, damp or peaty, from sea level up to 3000 m altitude.
Propagation and planting
Kigelia africana is readily propagated by seed; vegetative propagation using cuttings is possible but success rates are generally low. It is best grown in warm areas, due to cold intolerance. It is not frost resistant, but young plants will survive if protected for the first three years. In southern Africa it is reputedly quick-growing from seed. In other areas germination rate is poor. It is also propagated by wildings, and hardwood cuttings have been used successfully in experiments. It may be competitive to crops in arid areas where water is limiting.
Kigelia africana is not a prolific seeder; number of viable seeds per kg fibrous fruit pulp is between 3400 and 9700. Although it is sometimes advised that seed should not be stored, dry seeds store well under cool conditions. Seed storage behaviour is orthodox; viability is maintained for more than 3 years in airtight storage at ambient temperature with 1115% humidity. Although pre-treatment is not essential, seeds may be soaked in hot or boiling water for 1 minute prior to sowing. Seeds are pressed into seedling trays filled with pure river sand, covered with a shallow layer of sand or compost, and kept moist. Germination commences within 1025 days.
Diseases and pests
A rust disease caused by Newinia kigeliae has been reported.
Kigelia africana is not threatened. It is widely distributed and common in many regions. It is considered occasional in Kenya. In Malawi, its value as a wood source for dugout canoes is such that the tree is protected. Studies on the genetic variability are needed to elucidate the wide morphological variation.
Considering the many medicinal purposes for which it is used, there is enormous scope for future research of Kigelia africana, and further pharmacological investigation is warranted. Studies focusing on sustainable harvesting and management are necessary, in order to prevent mismanagement of the tree as it becomes increasingly popular commercially. Its potential for erosion control should be investigated.
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Sources of illustration
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Correct citation of this article:
Grace, O.M. & Davis, S.D., 2002. Kigelia africana (Lam.) Benth.. Record from Protabase. Oyen, L.P.A. & Lemmens, R.H.M.J. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources vιgιtales de lAfrique tropicale), Wageningen, the Netherlands.
Kigelia africana wild
1, leaf; 2, part of inflorescence; 3, fruit; 4, seed
Redrawn and adapted by W. Wessel-Brand
opening flower bud
fruiting tree habit