The shiny red and black seeds of Abrus precatorius subsp. africanus make it a sought after climber in the tropical and subtropical areas. In South Africa, it is distributed in KwaZulu-Natal, Gauteng and some parts of the Limpopo Provinces. There are some species similar to it and this may cause confusion. The bead vine is economically and medicinally important. Its leaves are consumed as a vegetable in central and east Africa. However, its seeds are very poisonous and can be dangerous to humans and animals if consumed.
Description of the plant
Abrus precatorius subsp. africanus is a slender, perennial climber that twines around trees, shrubs, and hedges. It has no special organs of attachment. It has slender branches and a cylindrical wrinkled stem with a smooth-textured brown bark. Leaves are glabrous with long internodes and are alternate compound paripinnate with stipules. Each leaf is 50-100 mm long. It bears from 20 to 24 or more leaflets, each of which is about 12-18 mm long, oblong and obtuse. It is blunt at both ends, glabrous on top and slightly hairy below. Flowers are small and pale violet with a short stalk, arranged in clusters. The ovary has a marginal placentation. The fruit, which is a pod, is f lat, oblong and truncate-shaped with a sharp, deflexed beak, 30-45 x 12 mm, and silky-textured. The pod curls back when opened to reveal pendulous seeds and contains from 3 to 5 oval-shaped seeds, about 6 mm long. They are usually bright scarlet with a smooth, glossy texture, and a black patch on top.
Abrus precatorius subsp. africanus is not listed on the Red Data List as a threatened species. Therefore, its conservation status is not well known or documented.
Habitat and distribution
Abrus precatorius subsp. africanus is a common plant in Kwazulu-Natal and Limpopo Province and native to many tropical areas of the world. A common weed of roadsides, old gardens, disturbed sites, waste areas and waterways (i.e. riparian areas) in the higher rainfall regions of subtropical areas. It has also been reported from open woodlands, rainforest margins and coastal dunes.
Derivation of name and historical aspects
Abrus precatorius L. is derived from the Greek word abrus which means delicate and refers to the leaflets; precatorius refers to petitioning and was chosen because of the use in rosaries. Abrus precatorius was described by Linnaeus in 1753 as Glycine abrus (the genus of Soya beans). In 1767, Adanson described the genus 'Abrus'. Much later, in 1970 Verdicourt used two subspecies for the African and Asian plants as they differed in their fruit. Abrus is a genus of 13-18 species in the family Fabaceae.
Abrus precatorius subsp. africanus reproduces mainly by seed. These seeds are thought to be mostly bird-dispersed, but it is likely that they are also spread along waterways during floods and in dumped garden waste.
Uses and cultural aspects
The plant secretes the toxin called abrin which is closely related to ricin. The symptoms of these toxins are severe stomach pains diarrhoea, nausea, cold sweat, drowsiness, colic and weak and fast pulse.
The seeds of Abrus precatorius are valued in making necklaces for their bright coloration. They are sold in stores and distributed throughout the world by travelers. They are favourite playing toys for children.
Growing Abrus precatorius L. subsp. africanus
Abrus precatorius is propogated by seed, which germinates faster if soaked in water. You can also place cuttings of strong shoots in sand and keep damp with plastic cones.
References and further reading
- Bailey, L.H. & Bailey, E.Z. 1976. Hortus third, edn 1: 3. Macmillan, New York.
- Bruneton, J. 1999. Toxic plants: dangerous to human and animals, edn 1: 287, Lavoisier Publishing, France.
- Dreisbach, R.H., 1971. Handbook of poisoning, Edn 7: 422, Lange Medical publications, Canada.
- Hardin, J.W. and Arena J.M., 1974. Human poisoning from native and cultivated plants, edn 2: 82. Duke University Press, Durham, North Carolina.
- Moll E&G, Strebel R.C., 1989. Poisonous Plants, edn 1: 19. Struik, Cape Town.
- Watt, J.M. and Breyer-Brandwijk M.G., 1932. Medicinal and poisonous plants of southern Africa : 77. Livingstone, Edinburgh & London.
- Watt, J.M. & Breyer-Brandwijk M.G. 1962. Medicinal and poisonous plants of southern Africa : 535. Livingstone, Edinburgh & London.
Thabo Thomas Masupa
Pretoria National Botanical Garden
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