Sesamum radiatum (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Vegetable
Vegetable oil
Medicinal
Food security

Sesamum radiatum Schumach. & Thonn.

Protologue: Enum. pl. hort. hafn., suppl. 2: 12 (1806).

Family: Pedaliaceae

Chromosome number: 2n = 64

Vernacular names

Black benniseed (En).

Origin and geographic distribution

Sesamum radiatum is of African origin and was taken into cultivation in Africa at an early date. It occurs wild in West and Central Africa and is cultivated there on a small scale. It does not occur in East and southern Africa (except northern Angola), but is sometimes cultivated and found naturalized in tropical Asia.

Uses

Fresh leaves of Sesamum radiatum are a popular leafy vegetable. Young shoots are finely cut for use in soups or sauces eaten with porridge. Cooked leaves have a slimy texture. Sesamum radiatum is sometimes grown for its seeds. These are consumed whole, toasted or after grinding as paste. An edible oil can be extracted from the seed, but this is rarely done, although the seed may be an adulterant of sesame seed (Sesamum indicum L.).

Sesamum radiatum has several medicinal and cosmetic uses. A cold leaf infusion is drunk to ease childbirth. A leaf infusion is used as a shampoo and to kill head lice. A mixture of paste from pounded seeds and shea butter and other ingredients is applied as a treatment for rectal prolapse. Filtrate of crushed leaves is drunk to treat metrorrhagia and a leaf maceration is used for bathing for the same purpose. Macerated fresh leafy stems are drunk as an antidote for scorpion stings; they are applied externally to treat sprains.

Production and international trade

Sesamum radiatum is only grown on a small scale, mainly for home consumption.

Properties

There is no information on the nutritional composition of Sesamum radiatum leaves, but it is probably comparable to that of Sesamum indicum leaves, which is per 100 g edible portion: water 85.5 g, energy 188 kJ (45 kcal), protein 3.4 g, fat 0.7 g, carbohydrate 8.6 g, fibre 2.4 g, Ca 77 mg, P 203 mg, riboflavin 0.3 mg (Leung, W.-T.W., Busson, F. & Jardin, C., 1968).

The seed contains 32.3% oil. The oil is similar in composition to sesame oil; its fatty acid composition is oleic acid 40%, linoleic acid 40%, palmitic acid 10% and stearic acid 7%. The oil contains the phenylpropanoid lignan sesamin (2.4%). This compound showed antioxidant, anti-inflammatory, antihypertensive, cytotoxic (including antitumour) and insecticidal activities.

Adulterations and substitutes

Several other Sesamum species and Ceratotheca sesamoides Endl. are used in similar ways as a potherb and for their edible oily seeds.

Description

Erect annual herb up to 120(–150) cm tall; stem simple or branched, glandular pubescent. Leaves opposite or alternate in upper part of plant, simple; stipules absent; petiole up to 2.5 cm long in lower leaves, short in upper leaves; blade lanceolate to ovate or elliptical, 3–10(–12) cm × 1.5–5(–7) cm, cuneate to obtuse at base, acute at apex, coarsely serrate in lower leaves, usually entire in upper leaves, pubescent and densely mealy glandular below. Flowers solitary in leaf axils, bisexual, zygomorphic, 5-merous, with 2 bracts at base, each bract with an axillary, sessile gland; pedicel (2–)3–4(–5) mm long; calyx with narrowly triangular lobes up to 7 mm long, connate at base; corolla obliquely campanulate, 2.5–5 cm long, pubescent, pink to purplish, sometimes white, lower lobe slightly longer than other lobes; stamens 4, inserted near base of corolla tube and included; ovary superior, 2-celled but each cell divided by a false septum almost to apex, style long and slender, with 2-lobed stigma. Fruit an oblong-quadrangular capsule 2–3.5 cm long, slightly compressed laterally, pubescent, with a very short beak at apex, often with 2 lateral short protuberances, loculicidally dehiscent, many-seeded. Seeds obovate in outline, compressed laterally, 2.5–3.5 mm × 1.5–2 mm, testa with radial sculptures, black or brown. Seedling with epigeal germination; hypocotyl 1–2 cm long; cotyledons broadly elliptical, up to 1 cm long, entire, leafy.

Other botanical information

Sesamum comprises about 20 species, most of which are indigenous to tropical Africa. Sometimes small horns can be present on fruits of Sesamum radiatum, and in that case confusion is possible with Ceratotheca sesamoides. In habit Sesamum radiatum resembles Sesamum indicum, but it can be distinguished by the testa structure (smooth in the latter species).

Sesamum radiatum and other Pedaliaceae are covered with mucilage glands. The mature secreting glandular hair consists of a head of 4 cap cells, which are attached to a stalk of 1–3 cells. The glands may enable the plant to withstand severe desiccation without tissue death. After contact with water, the outer cell walls of the head cells dissolve, producing an enormous amount of mucilage.

Growth and development

Sesamum radiatum shows indeterminate growth, so that flowering continues as long as environmental conditions permit, longer than is usual for sesame. In a germplasm evaluation trial in Kadugli, Sudan an accession identified as Sesamum radiatum continued growth for 2 months after all other accessions of sesame had senesced and were harvested.

Sesamum radiatum is primarily self-pollinated; the flowers open at dawn, after pollination has occurred. However, under extreme conditions some outcrossing may occur. It takes about 6 weeks from anthesis to fruit maturity. The fruits do not open fully; an angular pocket at the base of the fruit retains some seeds

Ecology

Sesamum radiatum is adapted to a wide range of habitats, but is most common in savanna. It occupies open localities where few other herbaceous plants grow. It occurs on nutritionally poor sites, growing in gravelly, sandy and rocky localities. It is also a weed and occurs in formerly cultivated fields. It tolerates heat and drought well and continues growth and flowering during the dry season.

Propagation and planting

The weight of 1000 seeds is about 2.5 g. Seed may be sown into seedbeds, in seed boxes or directly 2–3 seeds per hole. Germination takes 6–10 days. Seedlings are transplanted at a spacing of approximately 15 cm.

Management

Sesamum radiatum responds well to fertilizer. For leaf production plants are topped to promote the growth of new basal shoots from which larger leaves can be harvested. Plants in their second year may be pruned to a height of 2–5 cm to encourage new shoot production.

Diseases and pests

Phyllody (a mycoplasma disease) and stem fasciation appear in wild Sesamum species as well as sesame cultivars. Cercospora sesami may cause small black spots with diffuse edges on the leaves and also on the stems and fruits. Caterpillars of hawk moths (Sphingidae) may defoliate a plant in a few days. The caterpillars are parasitized by nematodes and flies that kill them before pupation. Larvae of another moth, Antigastra catalaunalis, damage the tops of plants. The green vegetable bug Nezara viridula feeds on the leaves, causing small brown spots.

Resistance to Antigastra catalaunalis (shoot webber), the root-knot nematode Meloidogyne incognita, Phytophthora blight, Fusarium wilt, leaf blight and seedling blight in Sesamum radiatum has been reported.

Harvesting

The first leaves can be harvested 8–10 weeks after sowing. Harvesting at 7–10-day intervals can continue for a period of about 14 weeks. Harvesting for seed is after about 4 months.

Yield

In Nigeria a leaf yield of 5–6 t/ha (5–6 kg per 10 m² bed) can be expected.

Handling after harvest

Leaves harvested in the rainy season may be dried and stored for use during the dry season. They are brought from the field, cleaned and spread out in the sun without prior blanching. After drying they are crushed to powder and stored in bags or plastic containers.

Genetic resources

Sesamum radiatum is widespread and occurs in various habitats, and is consequently not in danger of genetic erosion. No germplasm collections or breeding programmes are known to exist.

Prospects

Sesamum radiatum will probably remain of some importance in West Africa as it produces fresh leaves during the dry season.

Major references

• Bedigian, D., 2004. Slimy leaves and oily seeds: distribution and use of wild relatives of sesame in Africa. Economic Botany 58 (Suppl. S): S3-S33

• Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Volume 4, Families M–R. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 969 pp.

• Busson, F., 1965. Plantes alimentaires de l’ouest Africain: étude botanique, biologique et chimique. Leconte, Marseille, France. 568 pp.

• Dokosi, O.B., 1969. Some herbs used in the traditional systems of healing disease in Ghana-1. Ghana Journal of Science 9: 119–130.

• Gautier-Béguin, D., 1992. Plantes de cueillette à utilisation alimentaire en Côte d’Ivoire Centrale. Boissiera 46. 341 pp.

• Ihlenfeldt, H.-D., 1988. Pedaliaceae. In: Launert, E. (Editor). Flora Zambesiaca. Volume 8, part 3. Flora Zambesiaca Managing Committee, London, United Kingdom. pp. 86–113.

• Irvine, F.R., 1969. West African agriculture, 3rd Edition. Volume 2: West African Crops. Oxford University Press, London, United Kingdom. 272 pp.

• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.

• Stevels, J.M.C., 1990. Légumes traditionnels du Cameroun: une étude agrobotanique. Wageningen Agricultural University Papers 90–1. Wageningen Agricultural University, Wageningen, Netherlands. 262 pp.

Other references

• Bedigian, D., 1988. Sesamum indicum L. (Pedaliaceae): Ethnobotany in Sudan, crop diversity, lignans, origin, and related taxa. In: Goldblatt, P. & Lowry, P.P. (Editors). Modern systematic studies in African botany. AETFAT Monographs in Systematic Botany 25. Missouri Botanical Garden, St. Louis, United States. pp. 315–321.

• Bedigian, D., 2003. Evolution of sesame revisited: domestication, diversity and prospects. Genetic Resources and Crop Evolution 50(7): 773–778.

• Bedigian, D., 2003. Sesame in Africa: origin and dispersals. In: Neumann, K., Butler, A. and Kahlheber, S. (Editors). Food, fuel and fields: Progress in African archaeobotany. Africa Praehis-torica. Heinrich-Barth-Institute, Köln, Germany. pp. 17–36.

• Bedigian, D., Seigler, D.S., & Harlan, J.R., 1985. Sesamin, sesamolin and the origin of sesame. Biochemical Systematics and Ecology 13: 133–139.

• Hakki, M.I., 1984. Pedaliaceae. In: Brunel, J.F., Hiepko, P. & Scholz, H. (Editors). Flore Analytique du Togo. Deutsche Gesellschaft für Technische Zusammenarbeit, Eschborn, Germany. p. 383.

• Heine, H., 1963. Pedaliaceae. In: Hepper, F.N. (Editor). Flora of West Tropical Africa. Volume 2. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 388–391.

• Katende, A.B., Ssegawa, P. & Birnie, A., 1999. Wild food plants and mushrooms of Uganda. Technical Handbook No 19. Regional Land Management Unit/SIDA, Nairobi, Kenya. 490 pp.

• Lee, J.I., Lee, B.H., Seong, N.S. & Kang, C.W., 1991. Studies on interspecific hybridization in sesame. 1. Characteristics and cross affinity of wild sesame. Korean Journal of Breeding 22: 356–360.

• Leung, W.-T.W., Busson, F. & Jardin, C., 1968. Food composition table for use in Africa. FAO, Rome, Italy. 306 pp.

• Ogle, B.A., Malombo, L., Mingochi, D.S., Nkomesh, A. & Malasha, I., 1990. Traditional vegetables in Zambia, a study of procurement, marketing and consumption of traditional vegetables of selected urban and rural areas of Zambia. Rural Development Studies No 28. Swedish University of Agricultural Sciences, Uppsala, Sweden. 77 pp.

• Portères, R., 1951. Pousses et feuilles alimentaires employées par les peuplades de la zone montagneuse forestière de l'ouest Africain. Comptes Rendus. Première Conférence Internationale des Africanistes de l'Ouest. I.F.A.N. 2: 71–80.

• Thangavelu, S., 1994. Diversity in wild and cultivated species of sesame and its uses. In: Arora, A.K. & Riley, K.W. (Editors). Sesame biodiversity in Asia: conservation, evaluation and improvement. IPGRI, New Delhi, India. pp. 13–23.

• Watt, J.M. & Breyer-Brandwijk, M.G., 1962. The medicinal and poisonous plants of southern and eastern Africa. 2nd Edition. E. and S. Livingstone, London, United Kingdom. 1457 pp.

Sources of illustration

• Stevels, J.M.C., 1990. Légumes traditionnels du Cameroun: une étude agrobotanique. Wageningen Agricultural University Papers 90–1. Wageningen Agricultural University, Wageningen, Netherlands. 262 pp.

Author(s)

• D. Bedigian

Missouri Botanical Garden and Washington University, St. Louis, MO, United States

Correct citation of this article

Bedigian, D., 2004. Sesamum radiatum Thonn. ex Hornem. [Internet] Record from PROTA4U. Grubben, G.J.H. & Denton, O.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>.

Accessed 6 March 2025.

• See the Prota4U database.