Solanum anguivi (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

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

Solanum anguivi Lam.

Protologue: Tabl. encycl. 2: 23 (1794).

Family: Solanaceae

Chromosome number: 2n = 24

Synonyms

Solanum distichum Schumach. & Thonn. (1827), Solanum indicum auct. non L., Solanum anomalum auct. non Thonn.

Origin and geographic distribution

Solanum anguivi is native to Africa, widely distributed on the African continent and its neighbouring islands and Arabia. It has been recorded from West Africa, as well as Central Africa, East Africa, southern Africa and Madagascar, but it probably occurs in all non-arid regions throughout tropical Africa. It grows mostly in the wild, but sometimes, e.g. in Uganda and Côte d’Ivoire, it is a semi-cultivated vegetable.

Uses

The green fruits of Solanum anguivi are collected and consumed as a vegetable. In Ghana they are used as an appetizer. In Cameroon, the small bitter fruits are an important ingredient of a dish, called ‘nkwi’. Fruits are used fresh or dried and ground as medicine against high blood pressure. In compounds the plants with their masses of red berries are appreciated for their ornamental value.

Production and international trade

Solanum anguivi fruits are sold in local markets. As they are gathered from the wild or semi-cultivated in compounds, data on production and trade are not available.

Properties

The nutritional value of Solanum anguivi fruits is not reported, but is probably comparable to fruits of the related Solanum aethiopicum L. Solamargine and two steroid alkaloid glycosides, named anguivine and isoanguivine, have been isolated from the roots and three steroidal glycosides (anguiviosides A–C) from the fruits.

Adulterations and substitutes

As medicine against high blood pressure it can be replaced by dried scarlet eggplant fruits (Solanum aethiopicum Shum Group).

Description

Shrub up to 3 m tall with spreading branches; stem often prickly, bearing small, sessile stellate hairs with 4–8 arms. Leaves alternate, simple; stipules absent; petiole 2–6 cm long, densely stellate-hairy; blade elliptical-ovate, 10–20 cm × 5–10 cm, sinuate to distinctly lobed, with 2–4 pairs of lobes 2–3 cm long, base oblique, cuneate or occasionally truncate or subcordate, apex acute to obtuse, on both surfaces with more or less sessile stellate hairs having 6–10 more or less equal arms. Inflorescence a raceme-like cyme, extra-axillary, 5–15-flowered, occasionally flowers solitary. Flowers usually bisexual, occasionally the distal flowers with short styles and functionally male, regular, usually 5-merous; pedicel 4–15 mm long; calyx densely hairy, lobes c. 3 mm long; corolla stellate, 6–12 mm in diameter, white, occasionally with pale purple veins on the outer surface, stellate hairy outside, more or less glabrous inside; stamens alternate with corolla lobes, filaments short and thick, anthers connivent, yellow, opening by terminal pores; ovary superior, 2–6-celled, style about as long as stamens, stigma small. Fruit a subglobose berry 7–18 mm in diameter, smooth, green or white when young, red when ripe, in clusters of up to 20 fruits; stalk 8–15 mm long, usually erect, occasionally decurved. Seeds subreniform, 2–3 mm long. Seedling with epigeal germination; cotyledons thin, leafy.

Other botanical information

Solanum anguivi is a variable species. It exhibits tremendous variation in prickliness and pubescence, and in its inflorescence. This variation is possibly partly due to domestication and selection. There has been a shift from prickly, many-flowered and small-fruited types to prickleless, few-flowered and large-fruited types. Fully wild or weedy plants can have very prickly leaves and stems; such plants are usually weeded out and are thus not encountered in gardens. Solanum anguivi is often found in a semi-cultivated state. It is dispersed by birds, which drop the seeds after feeding on the berries.

Several subspecies and varieties of Solanum anguivi have been recognized. Solanum anguivi is most likely the wild progenitor of the scarlet eggplant (Solanum aethiopicum L.), commonly cultivated in tropical Africa, possibly via the semi-domesticated Solanum distichum Schumach. & Thonn., which is here considered as an element of Solanum anguivi, and which may well be treated as a cultivar-group. Solanum anguivi crosses with all groups within the Solanum aethiopicum complex, and the whole group might be considered as a single biological species. The F₁ plants, however, are less fertile, and the morphological differences are considerable; therefore they are considered here as two separate species. Occasionally Solanum anguivi is confused with Solanum torvum Sw., which has larger clusters of fruits.

Growth and development

Flowering starts 2–3 months after germination. Flowers open early in the morning when it is still dark. Solanum anguivi is mainly self-pollinated, but out-crossing by bees may take place. The stigma is receptive some hours before the flowers are open and remains receptive for about two days. Most plants survive for one rainy season and die in the dry season, but occasionally large plants of about two years old may be found.

Ecology

Solanum anguivi prefers relatively humid localities, being rare in arid ones. Usually it is found as a weed in gardens or disturbed areas. Primitive very prickly and hairy types can be found in forest habitats, ranging from primary to slightly disturbed forest.

Propagation and planting

The seeds are often dispersed by birds in farmers’ fields where the plants grow as a weed, but are often not removed by the farmers since the fruits are picked and eaten. Emergence of the seedling starts about a week after sowing. In gardens, plants are spaced 100–150 cm apart to allow for vigorous horizontal branching. Spacing may be wider if a few plants are left to grow in a garden among other crops.

Management

Since a few plants are normally found scattered in fields of other crops, there are no special management techniques for Solanum anguivi. Occasionally some branches may be pruned to stop the plant from becoming too bushy. Cultivation is rarely practised, but the same cultivation techniques as for Solanum aethiopicum may be used.

Diseases and pests

Solanum anguivi is susceptible to the rust Puccinia substriata var. indica, but in general it is very resilient and resistant to diseases and pests that affect many other Solanum species, e.g. bacterial wilt.

Harvesting

The harvest of the fruits starts 2.5–3 months after plant establishment. Fruits are ready for picking 2–3 weeks after fruit set, i.e. when they have reached a reasonable size but are still immature and green. Only the quantity needed for immediate consumption is picked. The crop keeps producing for up to a year or more. When seeds are required, fruits are allowed to reach full maturity turning orange-red in colour, i.e. about 4–6 weeks after fruit set.

Yield

A plant yields some handfuls of pea-sized fruits per month.

Handling after harvest

Fresh fruits of Solanum anguivi are easily transported and can be kept in good condition for some time, especially in shade or in a cool place. Sun-drying of fruits after cooking is practised to preserve them. The dried fruits are ground into powder and added to soup when required.

Genetic resources

Being mainly a weedy species and widely distributed in Africa, Solanum anguivi is not threatened. Farmers maintain the species by sparing the wanted types from being weeded from their fields. Over 50 samples of Solanum anguivi collected in the 1980s were kept at the University of Birmingham (United Kingdom), but most of the material has been taken over by the University of Nijmegen (Netherlands).

Breeding

Genetic improvement of Solanum anguivi has not been reported. However, it has been used in the breeding of other species. In Uganda, Solanum anguivi was crossed with Solanum aethiopicum to raise F₁, F₂, BC₁ and BC₂ generations to be evaluated for 15 quantitative and qualitative traits. Highly significant levels of hybrid vigour were detected in harvest date, number of fruits per plant, fruit size and weight, and leaf index. Fleshy and strongly attached versus thin and easily removed peduncle, green versus white colour of unripe fruits, and prickly versus non-prickly condition showed monogenic inheritance.

Prospects

Solanum anguivi is a valuable semi-domesticated indigenous vegetable in many areas, with potential to become a cultivated market vegetable. Breeding for plant habit, earliness, fruit quality and yield merits attention.

Solanum anguivi is of potential use as genitor in breeding programmes aimed at improvement of Solanum aethiopicum for disease resistance, e.g. to bacterial wilt (Ralstonia solanacearum), and to increase the number of fruits per infructescence.

Major references

• Bukenya-Ziraba, R., 1980. Studies in the taxonomy of Solanum L. in southern Ghana. MSc thesis. University of Ghana, Ghana. 194 pp.

• Bukenya-Ziraba, R., 1993. Studies in the taxonomy of genus Solanum in Uganda. PhD thesis. Makerere University, Kampala, Uganda. 456 pp.

• Schippers, R.R., 2000. African indigenous vegetables. An overview of the cultivated species. Natural Resources Institute/ACP-EU Technical Centre for Agricultural and Rural Cooperation, Chatham, United Kingdom. 214 pp.

• Schmelzer, G.H., 1990. Aubergines (Solanum spp.) des environs de Tai (Cote d'Ivoire). Bulletin du Muséum National d'Histoire Naturelle. Section B, Adansonia 12: 281–292.

Other references

• Anaso, H.U., 1991. Comparative cytological study of Solanum aethiopicum Gilo group, S. aethiopicum Shum group and S. anguivi. Euphytica 53(2): 81–86.

• Anaso, H.U., Okerere, G.U. & Uzo, J.O., 1990. Breeding for high yield of berries and improved yield attributes in Solanum aethiopicum L. Tropical Agriculture 67(4): 371–375.

• Bitter, G., 1923. Solana Africana 4. Feddes Repertorium, Beihefte, 16: 1–320.

• 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.

• Jaeger, P.M.L., 1985. Systematic studies in the genus Solanum in Africa. PhD thesis. University of Birmingham, United Kingdom.

• Lester, R.N. & Niakan, L., 1986. Origin and domestication of the Scarlet Eggplant, Solanum aethiopicum L., from S. anguivi Lam. In: D’Arcy, W.G. (Editor). Solanaceae: biology and systematics. Columbia University Press, New York, United States. pp. 433–456.

• Lester, R.N., Jaeger, P.M.L., Bleijendaal-Spierings, B.H.M., Bleijendaal, H.P.O. & Holloway, H.L.O., 1990. African eggplants - a review of collecting in West Africa. Plant Genetic Resources Newsletter 81/82: 17–26.

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

• Ripperger, H. & Himmelreich, U., 1994. Anguivine and isoanguivine, steroid alkaloid glycosides from Solanum anguivi. Phytochemistry 37(6): 1725–1727.

• USDA, ARS & National Genetic Resources Program, 2001. Germplasm Resources Information Network - (GRIN). [Internet] National Germplasm Resources Laboratory, Beltsville, Maryland, United States. http://www.ars-grin.gov/. June 2003.

• Wilson, J.P, Phatak, S.C. & Lovell, G., 1996. Aecial host range of Puccinia substriata var. indica. Plant Disease 80(7): 806–808.

• Zhu, X.H., Ikeda, T. & Nohara, T., 2000. Studies on the constituents of solanaceous plants. 46. Steroidal glycosides from the fruits of Solanum anguivi. Chemical and Pharmaceutical Bulletin 48(4): 568–570.

Sources of illustration

• Nabakooza, J., 2003. Illustration Solanum anguivi. Unpublished.

Author(s)

• R. Bukenya-Ziraba

Department of Botany, Makerere University, P.O. Box 7062, Kampala, Uganda

Correct citation of this article

Bukenya-Ziraba, R., 2004. Solanum anguivi Lam. [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 18 December 2024.

• See the Prota4U database.