Kigelia is a genus of flowering plants in the family Bignoniaceae. The genus consists of only one species, Kigelia africana, which occurs throughout tropical Africa. The so-called sausage tree grows a poisonous fruit that is up to 60 cm (2 feet) long, weighs about 7 kg (15 pounds), and resembles a sausage in a casing. The genus name comes from the Mozambican Bantu name, kigeli-keia, while the common names sausage tree and cucumber tree refer to the long, sausage-like fruit. Its name in Afrikaans worsboom also means sausage tree, and its Arabic name means "the father of kit-bags". It is a tree growing up to 20 m (66 feet) tall and it typically has spreading branches. The bark is grey and smooth at first, peeling on older trees. It can be as thick as 6 mm (1⁄4 inch) on a 15-centimetre (5.9 in) diameter branch. The wood is pale brown or yellowish, undifferentiated and not prone to cracking.
The tree is evergreen where rainfall occurs throughout the year, but deciduous where there is a long dry season. The leaves are opposite or in whorls of three, 30 to 51 cm (12 to 20 inches) long, pinnate, with six to ten oval leaflets up to 20 cm (8 inches) long and 5.7 cm (2+1⁄4 inches) broad,the terminal leaflet can be either present or absent.
The flowers (and later the fruit) hang down from branches on long flexible stems (2–6 m or 7–20 ft long). According to author/nature photographer Winston Williams, these stems, or peduncles can be up to 7.5 m (25 ft) in length. Flowers are produced in panicles; they are bell-shaped (similar to those of the African tulip tree but broader and much darker and more waxy), orange to maroon or purplish green, and about 10 cm (4 inches) wide. Individual flowers do not hang down but are oriented horizontally.
The fruit is a woody berry from 30 to 99 cm (12 to 39 inches) long and up to 18 cm (7 inches) broad, but 20 cm (8 inches) has been reported. Typically it weighs between 5 and 10 kg (11 and 22 pounds) but occasionally up to 12 kg (26 pounds), and hangs down on long, rope-like peduncles. The fruit pulp is fibrous, containing many seeds.
Some birds are attracted to the flowers and the strong stems of each flower make ideal footholds. Their scent is most notable at night indicating that they are adapted to pollination by bats, which visit them for pollen and nectar. The flowers also remain open by day however, and are freely visited by many insect pollinators, particularly large species such as carpenter bees. The fruit are eaten by several species of mammals, including baboons, bushpigs, savannah elephants, giraffes, hippopotamuses, monkeys, and porcupines. The seeds are dispersed in their dung. The seeds are also eaten by brown parrots and brown-headed parrots, and the tree's foliage by elephants and greater kudu (Joffe 2003; del Hoyo et al. 1997). Introduced specimens in Australian parks are very popular with cockatoos.
Cultivation and uses
The fresh fruit is poisonous and strongly purgative; fruit are prepared for consumption by drying, roasting or fermentation (Joffe 2003; McBurney 2004). In Botswana, the timber is used for makoros, yokes and oars.
Extracts of the bark, flower and fruit of Kigelia Africana have been increasingly used in skincare products due to the high level of anti oxidant and anti inflammatory constituents. It has high skin firming efficacy due to its properties as a Phyto hormone.
The hard shell (skin) of the fruit can be hollowed out, cleaned, and made into useful, durable containers of varying sizes.
The tree is widely grown as an ornamental tree in tropical regions for its decorative flowers and unusual fruit. Planting sites should be selected carefully, as the falling fruit can cause serious injury to people and damage vehicles parked under the trees.
In Central Kenya, especially among the Agikuyu and the Akamba, the dried fruits are used to make an alcoholic beverage (muratina in Kikuyu, kaluvu in Kamba), which is a core component in cultural events in Central Kenya. The fruit is harvested then split into two along the grain, then dried in the sun. The dried fruit is then treated with bee pollen and honey. The treated fruit (miatine) is then used in fermentation process in making of sweet beer. There are many anecdotal uses of the sausage tree. The powdered mature fruit is applied as a dressing in the treatment of wounds, abscesses, and ulcers. The green fruit is used as a poultice for syphilis and rheumatism, and a poultice made from leaves is used as a treatment for backache. Pharmacological investigations conducted confirm the anti-inflammatory, analgesic, antioxidant and anticancer activity of the extract of different parts of the plant. Bioactive constituents are found to be present in all parts of the plant. So far, approximately 150 compounds have been characterized from different part of the plant. Iridoids, naphthoquinones, flavonoids, terpenes and phenylethanoglycosides are the major class of compounds isolated. Novel compounds with potent antioxidant, antimicrobial and anticancer effect such as verbascoside, verminoside and pinnatal among others, have been identified. Commercial trade of K. africana has boosted in the las few decades. Its effect in the maintenance of skin has been recognized resulting in a handful of skin formulations in the market. The pharmaceutical potentials of K. africana has been recognized and have witness a surge in research interest. However, till date, many of its traditional medicinal uses has not been investigated scientifically. Further probing of the existential researches on its pharmacological activity is recommended with the end-goal of unravelling the pharmacodynamics, pharmacokinetics, clinical relevance and possible toxicity and side effects of both the extract and the active ingredients isolated.