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Schwenckia americana L.

Protologue
Gen. pl. ed. 6: 577 (1764).
Family
Solanaceae
Origin and geographic distribution
Schwenckia americana is native to Central and South America, but it has spread to tropical Africa and India as a weed. In tropical Africa it was restricted to West and Central Africa, but in recent decades it has also reached East and southern Africa.
Uses
The aerial parts are widely valued in West Africa to treat diseases of babies and small children. A leaf decoction is given to pregnant women when the foetus develops too slowly and is taken by breast-feeding women to prevent diarrhoea of the baby. The roots are chewed to cure respiratory diseases in children. A root decoction is given to babies as a purgative.
An infusion of the aerial parts is used as a mouth wash to cure infections such as aphthae. The plant sap or a decoction of the whole plant is applied as eye drops and nose drops to treat headache, sinusitis and conjunctivitis. In different preparations the crushed whole plant, alone or combined with other plants, is externally applied to relieve intercostal pain or pain caused by swellings, rheumatism, arthritis, stomach problems, hernia and gonorrhoea; it is also applied as an anthelmintic. The crushed leafy stems are applied to the skin against measles and chickenpox. A poultice made of the leaves is applied to whitlow and athlete’s foot. Powder from leafy twigs is inhaled to cure convulsions with fever. A decoction of the whole plant is drunk to cure cough, asthma and weak lungs, and as a purgative in cases of poisoning. A leaf decoction is drunk and applied externally to bring fever down and to cure oedema. In Ghana and DR Congo a leaf infusion is taken to treat female sterility. A root decoction is taken as a laxative. In India both fresh and dried leaves are used as an anthelmintic. The whole plant is pounded to pulp for use as an effective fish poison. Roots and stems are used as chewing sticks for cleaning the teeth.
Properties
Preliminary research in the 1960s resulted in the detection of a glycoside, schwenckioside, traces of alkaloids and sapogenins, the latter with cardiotonic activity. A water extract of the leaves showed low antimicrobial activity against Proteus mirabilis and Staphylococcus aureus, but no inhibition of Pseudomonas aeruginosa and Escherichia coli.
Botany
Annual or short-living perennial herb, erect or ascending and spreading, up to 70(–100) cm tall; stem grooved, glabrous but young parts sometimes with curved hairs. Leaves arranged spirally, simple and entire; stipules absent; petiole up to 8 mm long; blade ovate to obovate, up to 4 cm × 2 cm, base cuneate to rounded, apex acute to rounded, almost glabrous to densely short-hairy. Inflorescence a lax, terminal panicle, many-flowered; peduncle 2–12 cm long, slightly longer in fruit. Flowers bisexual, slightly zygomorphic; pedicel 2–4 mm long, erect or curved; calyx tubular, 2–4 mm long, 4–5-lobed, lobes acute to acuminate; corolla narrowly tubular, 6–8 mm long, white, greenish yellow, pale blue to purplish, lobes unequal, up to 0.5 mm long; stamens 2, attached to corolla tube, filaments 0.5–3 mm long, staminodes 3, resembling filaments; ovary superior, ellipsoid, 1–2 mm long, style 3–6 mm long, stigma small, exserted. Fruit a globose or ovoid capsule 3.5–4.5 mm × 2.5–4.5 mm, pale brown, dehiscent, many-seeded. Seeds prismatic, 0.5–1 mm long, black or reddish. Seedling with epigeal germination.
Schwenckia comprises about 22 species, all native to tropical America. Schwenckia americana is the only species that has spread to other continents. The orthographic variation ‘ Schwenkia’ is very common in the literature.
Ecology
Schwenckia americana is a weed in fields, woodland and disturbed localities, up to 1100 m altitude.
Management
Schwenckia americana can by propagated by seed or cuttings; it is only harvested from the wild.
Genetic resources and breeding
Schwenckia americana is widespread and common in anthropogenic habitats and not in danger of genetic erosion. There are a few samples in gene banks.
Prospects
Better knowledge of the pharmacological properties of Schwenckia americana is needed for a proper assessment of its medicinal value in the future.
Major references
• Aké-Assi, L., Guinko, S. & Aya-Lazare, A., 1991. Plantes utilisées dans la médecine traditionnelle en Afrique de l’Ouest. Edition Roche, Basel, Switzerland. 151 pp.
• Burkill, H.M., 2000. The useful plants of West Tropical Africa. 2nd Edition. Volume 5, Families S–Z, Addenda. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 686 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.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Nkounkou-Loumpangou, C., Binimbi-Massengo, A., Nzonzi, J., Ouamba, J.M., Abena, A.A. & Diatewa, M., 2005. Inventaire des plantes médicinales utilisées dans le traitement de l’infertilité féminine à Brazzaville. Phytothérapie 6: 252–259.
Other references
• Adamu, H.M., Abayeh, O.J., Agho, M.O., Abdullahi, A.L., Uba, A., Dukku, H.U. & Wufem, B.M., 2005. An ethnobotanical survey of Bauchi State herbal plants and their antimicrobial activity. Journal of Ethnopharmacology 99(1): 1–4.
• Adjanohoun, E.J., Adjakidjè, V., Ahyi, M.R.A., Aké Assi, L., Akoègninou, A., d’Almeida, J., Apovo, F., Boukef, K., Chadare, M., Cusset, G., Dramane, K., Eyme, J., Gassita, J.N., Gbaguidi, N., Goudote, E., Guinko, S., Houngnon, P., Lo, I., Keita, A., Kiniffo, H.V., Kone-Bamba, D., Musampa Nseyya, A., Saadou, M., Sodogandji, T., De Souza, S., Tchabi, A., Zinsou Dossa, C. & Zohoun, T., 1989. Contribution aux études ethnobotaniques et floristiques en République Populaire du Bénin. Agence de Coopération Culturelle et Technique, Paris, France. 895 pp.
• Adjanohoun, E.J., Ahyi, M.R.A., Aké Assi, L., Dan Dicko, L., Daouda, H., Delmas, M., de Souza, S., Garba, M., Guinko, S., Kayonga, A., N'Golo, D., Raynal, J. & Saadou, M., 1985. Médecine traditionnelle et pharmacopée - Contribution aux études ethnobotaniques et floristiques au Niger. Agence de Coopération Culturelle et Technique, Paris, France. 250 pp.
• Audu, J., 1995. Studies on the effectiveness of medicinal herbs used as anthelmintics by traditional medical practitioners in south of Bauchi State. Journal of Economic and Taxonomic Botany 19(3): 653–661.
• CAB International, 2004. Prevention and management of alien invasive species: forging cooperation throughout West Africa. Proceedings of a Workshop held in Accra, Ghana, 9–11 March 2004. CAB International, Nairobi, Kenya. 109 pp.
• Hermans, M., Akoègninou, A. & van der Maesen, J., 2004. Medicinal plants used to treat malaria in southern Benin. Economic Botany 58 (supplement): S239–S252.
• Hodouto, K.-K., 1990. Etude chimique des plantes à flavonoïdes du Togo. Bulletin de Médecine Traditionnelle et Pharmacopée 4(1): 31–48.
• Iwu, M.M., 1993. Handbook of African medicinal plants. CRC Press, Boca Raton, Florida, United States. 464 pp.
• Kibungu Kembelo, A.O., 2004. Quelques plantes medicinales du Bas-Congo et leurs usages. DFID, London, United Kingdom. 197 pp.
• Latham, P., 2004. Useful plants of Bas-Congo province, Democratic Republic of the Congo. DFID, London, United Kingdom. 320 pp.
Sources of illustration
• Akoègninou, A., van der Burg, W.J. & van der Maesen, L.J.G. (Editors), 2006. Flore analytique du Bénin. Backhuys Publishers, Leiden, Netherlands. 1034 pp.
Author(s)
C.H. Bosch
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
G.H. Schmelzer
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
A. Gurib-Fakim
Faculty of Science, University of Mauritius, Réduit, Mauritius
Associate editors
C.H. Bosch
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
M.S.J. Simmonds
Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, United Kingdom
R. Arroo
Leicester School of Pharmacy, Natural Products Research, De Montfort University, The Gateway, Leicester LE1 9BH, United Kingdom
A. de Ruijter
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Photo editor
A. de Ruijter
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Bosch, C.H., 2008. Schwenckia americana L. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, plant habit; 2, flower; 3, fruit; 4, dehisced fruit.
Source: Flore analytique du Bénin



flowering plant