Solanum nigrum (PROTA)

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Plant Resources of Tropical Africa
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Solanum nigrum L.


Protologue: Sp. pl. 1: 186 (1753).
Family: Solanaceae
Chromosome number: 2n = 72

Vernacular names

  • Black nightshade, common nightshade, garden nightshade (En).
  • Morelle noire, brède martin, herbe à calalou (Fr).
  • Erva moura (Po).
  • Suga, mnavu (Sw).

Origin and geographic distribution

The exact origin of Solanum nigrum is unknown, but it is generally considered to be native to Europe and Asia and possibly also Africa. Solanum nigrum (hexaploid) is thought to have been derived from the tetraploid Solanum villosum Mill. and the diploid Solanum americanum Mill., but possibly more taxa have been involved. It is very well adapted to the Mediterranean climate and possibly originated there. It has certainly been introduced in North America, New Zealand and Australia and has not yet been found in South and Central America or on the islands of the Pacific Ocean. In Africa it is probably widely distributed, but accurate taxonomic work has yet to be carried out in many countries.

Uses

Solanum nigrum has many uses, but determination of the true identity of the plants called Solanum nigrum in the literature is mostly impossible and some of the uses listed here may apply to closely related species.

The medicinal use of Solanum nigrum probably goes back more than 2000 years. The plants are used as an emollient and analgesic to treat itch, burns and neuralgic pains, and are also considered to be expectorant and laxative. The leaves are said to have sedative and healing properties and are applied to cuts, ulcers, wounds, inflammations and skin diseases. A decoction of the leaves is used to treat yaws. The fruit is considered to be a cure for diabetes. Diuretic properties are also attributed to the plant. An extract of the leaves and stem is used for treating dropsy, heart diseases, piles, gonorrhoea, fevers, eye diseases and chronic enlargement of liver and spleen. In Tanzania the roots are eaten to treat stomach-ache.

The leaves and young shoots of Solanum nigrum are probably collected from the wild like other Solanum spp. and eaten boiled as a vegetable. It is recommended that the cooking water is refreshed a number of times. However, it has been recorded, e.g. in Ethiopia, that the leaves taste bitter and are only eaten when more tasty vegetables are not available. Fruits are said to be poisonous, but there are records of fruits being eaten when ripe. Most reports state that unripe fruits are particularly poisonous.

Properties

When the leaves of Solanum nigrum are eaten regularly (several times a week) they are said to cause stomach-ache because of the presence of toxic glyco-alkaloids such as solanine (with aglycon solasodine). Total alkaloid content of air-dried leaves is 0.1%. Solanine poisoning can cause vomiting, dizziness, mental confusion, loss of speech and sometimes blindness. Solanum nigrum also contains the sapogenins diosgenin and tigogenin. Unripe berries contain 0.7% solasodine, 0.2% diosgenin and 0.15% tigogenin; leaves contain 1.3% tigogenin.

The powdered aerial parts of Solanum nigrum and their methanolic extract significantly reduced gastric ulcer formation in rats, and an alcoholic fruit extract showed significant inhibition of carrageenin-induced oedema. An alcoholic leaf extract was active against Staphylococcus aureus and Escherichia coli. Some other pharmacological activities include antispasmodic, hypotensive, hypocholesterolaemic and anti-HIV-1 activities, as well as insecticidal and molluscicidal activities.

Description

Annual herb up to 70 cm tall, with decumbent or erect stem, glabrous to long-hairy with simple multicellular hairs, glandular or not. Leaves arranged spirally, simple; stipules absent; petiole 0.5–6.5 cm long, slightly winged towards apex; blade ovate to lanceolate-rhombic, 2.5–10 cm × 2–7 cm, base cuneate, apex obtuse, margin entire to wavy-toothed. Inflorescence an extra-axillary raceme-like cyme, 3–12-flowered; peduncle 1–3 cm long. Flowers bisexual, regular, 5-merous; pedicel recurved in fruit; calyx campanulate, up to 2.5 mm long with ovate lobes, deflexed or adhering to the base of the mature fruit; corolla stellate, 0.5–1 cm in diameter, white with yellow-green basal star, lobes 1.5–4 mm long; stamens inserted on corolla throat, filaments up to 1.5 mm long, anthers up to 2.5 mm long; ovary superior, globose to ellipsoid, c. 1 mm in diameter. Fruit a globose to ovoid berry 6–10 mm in diameter, dull purple to blackish or sometimes yellow-green, many-seeded. Seeds flattened, obovoid, c. 2 mm long, creamy, minutely pitted.

Other botanical information

Solanum nigrum belongs to the subgenus Solanum and section Solanum, together with species such as Solanum americanum Mill., Solanum florulentum Bitter, Solanum grossedentatum A.Rich., Solanum scabrum Mill., Solanum tarderemotum Bitter and Solanum villosum Mill. Many of the species in section Solanum have been named Solanum nigrum in the past and thus references to Solanum nigrum in the literature must be interpreted with great caution. Research is still needed to better understand the species within section Solanum and their diversity.

Solanum nigrum can be divided into 2 subspecies: subsp. nigrum (glabrous to slightly hairy with appressed, non-glandular hairs) and subsp. schultesii (Opiz) Wessely (densely hairy with patent, glandular hairs). However, the distinction is not everywhere clear.

Ecology

Solanum nigrum often occurs as a weed in fields, but also in wasteland, roadsides and disturbed localities, in full sunshine or in slight shade, from sea-level up to 3000 m altitude.

Genetic resources

Solanum nigrum is variable and widespread and not in danger of genetic erosion. A germplasm collection is available at the Botanical and Experimental Garden of Nijmegen University, Netherlands.

Prospects

Solanum nigrum will remain a minor leafy vegetable, particularly of importance in times of food scarcity. Its toxic components do not allow large-scale consumption and may make use as a medicinal plant hazardous.

Major references

  • Blomqvist, M.M. & Nguyen Tien Ban, 1999. Solanum L. In: de Padua, L.S., Bunyapraphatsara, N. & Lemmens, R.H.M.J. (Editors). Plant Resources of South-East Asia No 12(1). Medicinal and poisonous plants 1. Backhuys Publishers, Leiden, Netherlands. pp. 453–460.
  • Bukenya-Ziraba, R. & Carasco, J.F., 1995. Solanum (Solanaceae) in Uganda. Bothalia 25(1): 43–59.
  • Edmonds, J.M. & Chweya, J.A., 1997. Black nightshades. Solanum nigrum L. and related species. Promoting the conservation and use of underutilized and neglected crops 15. Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany/International Plant Genetic Resources Institute, Rome, Italy. 113 pp.
  • Gonçalves, A.E., 2005. Solanaceae. In: Pope, G.V., Polhill, R.M. & Martins, E.S. (Editors). Flora Zambesiaca. Volume 8, part 4. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 124 pp.
  • Katambo, M.L.M., 2007. A systematic study of African Solanum L. Section Solanum (Solanaceae). PhD thesis, Radboud University, Nijmegen, Netherlands. 154 pp.

Other references

  • Bukenya-Ziraba, R., 1996. Uses, chromosome number and distribution of Solanum species in Uganda. In: van der Maesen, L.J.G., van der Burgt, X.M. & van Medenbach-de Rooy, J.M. (Editors). Proceedings 14th AETFAT congress, 22–27 August 1994, Wageningen, Netherlands. Kluwer Academic Publishers, Dordrecht, Netherlands. pp. 33–37.
  • Bukenya-Ziraba, R. & Carasco, J.F., 1999. Ethnobotanical aspects of Solanum L. (Solanaceae) in Uganda. In: Nee, M., Symon, D.E., Lester, R.N. & Jessop, J.P. (Editors). Solanaceae 4: Advances in biology and utilization. Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 345–360.
  • Bukenya-Ziraba, R. & Hall, J.B., 1988. Solanum (Solanaceae) in Ghana. Bothalia 18(1): 79–88.
  • Debray, M., Jacquemin, H. & Razafindrambao, R., 1971. Contribution à l’inventaire des plantes médicinales de Madagascar. Travaux et Documents No 8. ORSTOM, Paris, France. 150 pp.
  • Decary, R., 1946. Plantes et animaux utiles de Madagascar. Annales du Musée Colonial de Marseille, 54e année, 6e série, 4e volume, 1er et dernier fascicule. 234 pp.
  • Edmonds, J.M., 1977. Taxonomic studies on Solanum section Solanum (Maurella). Botanical Journal of the Linnean Society 75: 141–178.
  • Edmonds, J.M., 1979. Biosystematics of Solanum L. section Solanum (Maurella). Botanical Journal of the Linnean Society 76: 27–51.
  • Gurib-Fakim, A., Guého, J. & Bissoondoyal, M.D., 1997. Plantes médicinales de Maurice, tome 3. Editions de l’Océan Indien, Rose-Hill, Mauritius. 471 pp.
  • Nacro, M. & Millogo-Rasolodimbi, J., 1993. Plantes tinctoriales et plantes à tanins du Burkina Faso. Editions ScientifikA, Amiens, France. 152 pp.
  • van Wyk, B.E. & Gericke, N., 2000. People’s plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria, South Africa. 351 pp.

Sources of illustration

  • Blomqvist, M.M. & Nguyen Tien Ban, 1999. Solanum L. In: de Padua, L.S., Bunyapraphatsara, N. & Lemmens, R.H.M.J. (Editors). Plant Resources of South-East Asia No 12(1). Medicinal and poisonous plants 1. Backhuys Publishers, Leiden, Netherlands. pp. 453–460.

Author(s)

  • P.C.M. Jansen, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Jansen, P.C.M., 2008. Solanum nigrum L. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 8 July 2021.