Sesamum eriocarpum (Decne.) Byng & Christenh. (= Dicerocaryum eriocarpum (Decne.) Abels
Common names: devil’s thorn (Eng.); beesdubbeltjie, duiwelsdoring, seepbos (Afr.); intekelane (Ndebele); makanagwe (Tswana)
Sesamum eriocarpum is a perennial herb which creeps along the ground in the Kalahari, with beautiful, bright mauve flowers that magnificently compliment the dull desert soils. This plant was used by the Khoi and San people in traditional spa treatments. It is also known as devil’s thorn because of its circular fruit having two central sharp projections.
Sesamum eriocarpum is a prostrate herb, with creeping, densely hairy stems.
Leaves are opposite, egg-shaped in outline and attached at the broad end; they are 22 mm long, with rounded teeth along the margins.
Flowers are bright mauve, usually with dark spots in the throat and lower lip. These trumpet-shaped flowers are solitary, 22–24 mm long, supported by pedicels that are 14–25 mm long. It flowers in summer, mainly from December to April.
Fruits are circular in shape, hairy, 12–22 mm long and 11–19 mm wide, with two central spines that are 4–5 mm long. The fruit bears seeds that are oblanceolate, ± 5.5 mm long and 2.2 mm wide.
Sesamum eriocarpum is not threatened, and is assessed on the Red List of South African Plants as Least Concern (LC).
Distribution and habitat
Devil’s thorn occurs in the Democratic Republic of Congo, Zambia, Zimbabwe, Namibia, Botswana and South Africa. In South Africa it grows in the Limpopo, Northern Cape and North West Provinces. It occurs mainly in desert areas, but it also grows on sandy soils in grasslands, riverbanks and on dunes slopes at altitudes of 900–1 200 mm.
Derivation of name and historical aspects
This species was previously placed in the genus Dicerocaryum. The species that were previously classified in Dicerocaryum are now considered to be genetically and morphologically indistinct from plants in the genus Sesamum and all species have thus been transferred.
The genus name Dicerocaryum is derived from two Greek words, dikeros, meaning ‘two-thorned’, and karyon, meaning ‘walnut’, which describes the circular fruit with two spines. The genus name Sesamum is the Greek and Latin name for sesame, Sesamum indicum. The species name eriocarpum is also derived from two Greek words, erion meaning ‘wool’ and karpos meaning ‘fruit’, which refers to the hairy fruit of the plant.
The thorny fruits stick into the feet and hooves of animals and are carried off and dispersed in this way.
Sesamum eriocarpum was a popular plant among the Khoi and San people of southern Africa. It contains saponins, which are glycosides with a unique foaming characteristic. When the flowers are soaked in water, they produce a mucilaginous substance that was used as soap and shampoo. It was also used by Khoi and San women for tradition foot spas. They would soak the flowers in calabashes, immersing their feet in them for some time. Intekelane was also used for hunting. The dried roots were crushed together with the roasted seed pods of Snake Bean, Bobgunnia madagascariensis (= Swartzia madagascariensis), to make a poisonous substance that was applied to arrows before a hunting trip.
Sesamum eriocarpum is also known for its antibacterial and anti-inflammatory properties. In Botswana, the roots are boiled and taken orally to heal sexually transmitted diseases. During childbirth, an infusion of the whole plant is taken orally and inserted into the vagina to dilate the birth canal. An infusion of the whole plant can be taken orally to cause an abortion. Powdered roots can be mixed with porridge to ease abdominal pains. An infusion of the leaves is also used as body wash to treat measles in children.
In Namibia, the roots are dried, powdered and prepared into a decoction for the treatment of malaria. Plants should be taken in small quantities, as large doses often cause toxicity in patients.
In South Africa, the Venda people of Limpopo Province consume the leaves as a vegetable. Indigenous farmers also use the plant for treating wounds and retained placentas in livestock.
Growing Sesamum eriocarpum
Sesamum eriocarpum is best propagated by seeds. However, it is a challenge to extract the individual seeds from the fruit without crushing them. One can use a nut cracker to break the pod open or the entire pod can be sown into the soil. When the pod breaks open, the seed will sprout.
Individual seeds or entire pods can be sown 5 cm deep into a medium consisting of ¼ potting mix and ¾ sand. The pots should be placed in direct sunlight and watered once a week. Once the seeds have germinated, pest control might be needed as white flies and spider mites are fond of this plant. Propagation should be done preferably in summer, as the seeds are dormant in winter. Seedlings should be kept in doors and away from frost in winter.
- Christenhusz, M.J.M., Fay, M.F.F. & Byng, J.W. 2018. The Global Flora. A practical flora to vascular plant species of the world. Special edition. GLOVAP Nomenclature Part 1. Plant Gateway, Bradford.
- Du Preez, I. et al. 2016. Indigenous use of plants to treat malaria and associated symptoms. In K.C. Chinsembu & Ahmad Cheikhyoussef (eds), Indigenous knowledge of Namibia (pp. 41–57), University of Namibia Press, Windhoek.
- Foden, W. & Potter, L. 2005. Dicerocaryum eriocarpum (Decne.) Abels. National Assessment: Red List of South African plants version 2015.1. Retrieved 21 October 2016.
- Grimshaw, J. 2009. A not so simple garden: African Pedaliaceae. http://geraniosgarden.blogspot.co.za/2009/12/african-pedaliaceae.html, retrieved 21 October 2016.
- Hyde, M.A., Wursten, B.T., Ballings, P. & Coates Palgrave, M. 2016. Flora of Zimbabwe: Species information: Dicerocaryum eriocarpum. http://www.zimbabweflora.co.zw/speciesdata/species.php?species_id=152600, retrieved 21 Oct 2016.
- Ihlenfeldt, H.D. 1988. Dicerocaryum eriocarpum Decne. Flora zambesiaca 8 (3): 86.
- iSpot southern Africa http://www.ispotnature.org/species-dictionaries/sanbi/Dicerocaryum%20eriocarpum?nav=search accessed 24/01/17
- Luseba, D. et al. 2007. Antibacterial, anti-inflammatory and mutagenic effects of some medicinal plants used in South Africa for the treatment of wounds and retained placenta in livestock. South African Journal of Botany 73 (3): 378–383.
- Moreki, J C., Tshireletso, K. & Okoli, I.C. 2012. Potential use of ethnoveterinary medicine for retained placenta in cattle in Mogonono, Botswana. Journal Animal Production Advance 2 (6): 303–309.
- Mukanganyama, S. et al. 2011. Screening for anti-infective properties of selected medicinal plants from Botswana. African Journal of Plant Science and Biotechnology 5 (1): 1–7.
National Herbarium, Pretoria
updated September 2023
Plant Type: Ground Cover, Perennial
SA Distribution: Limpopo, North West, Northern Cape
Soil type: Sandy
Flowering season: Early Summer, Late Summer, Autumn
PH: Acid, Neutral
Flower colour: Mauve/Lilac
Aspect: Full Sun
Gardening skill: Challenging