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Strophanthus speciosus (N.B.Ward & Harv.) Reber

Protologue
Fortschr. (Genf) 3: 299 (1887).
Family
Apocynaceae
Chromosome number
2n = 18
Vernacular names
Common poison rope, forest poison rope (En).
Origin and geographic distribution
Strophanthus speciosus occurs in Zimbabwe, South Africa and Swaziland.
Uses
Strophanthus speciosus is used to treat snakebites in humans and cattle. For humans the powdered root is sniffed or the root is chewed and the sap is swallowed, while spoonfuls of roasted pulverized root are given to cattle. It is possibly also used as an arrow poison and for criminal purposes.
Properties
From seeds of Strophanthus speciosus the cardiac glycosides (cardenolides) strospeside and christyoside have been isolated. Strospeside also occurs in Adenium spp.
Botany
Shrub up to 4 m tall or liana up to 16 m long, with clear or white exudate; stem up to 3 cm in diameter, branching trichotomously; branches with rather many lenticels, branchlets glabrous. Leaves in whorls of 3, simple and entire; stipules absent; petiole 2–12 mm long; blade narrowly elliptical to slightly obovate, 2–11.5 cm Χ 1–3.5 cm, base decurrent into the petiole, apex acute or acuminate, margin often slightly revolute, papery, glabrous. Inflorescence a congested terminal dichasial cyme, on long branches or in the trichotomous forks, usually glabrous, few- to many-flowered; peduncle 3–16(–23) mm long; bracts narrowly ovate, 1.5–10.5 mm long, deciduous. Flowers bisexual, regular, 5-merous; pedicel 6–21 mm long; sepals slightly unequal, narrowly ovate, 3–14.5 mm long, acute, with some hairs near the apex or hairy all over; corolla tube 9–14 mm long, widening at 30–50% of its length into a cup-shaped upper part, at the mouth 5.5–11 mm wide, yellow turning orange, outside white near the base, inside red streaked, corona lobes subulate, 2–5 mm Χ 1–2 mm, acute or obtuse, fleshy, white, corolla lobes ovate, gradually narrowing into the 1–1.5 mm wide spreading tails, lobes including the tail 19–50 mm long, yellow on both sides, with a red spot near the base, tails yellow; stamens inserted at 4–6.5 mm from the base of the corolla tube, included; ovary half-inferior, 2-celled, hairy, style 4–5.5 mm long, ending in a ringlike pistil head surrounding the minute stigma. Fruit consisting of 2 ellipsoid follicles (7–)10–22 cm Χ 1–1.5 cm, tapering into a narrow apex, 2-valved, divergent at (60–)100–230°, wall thick and hard, glabrous or densely short-hairy, many-seeded. Seeds almost spindle-shaped, slightly flattened, 13–22 mm Χ 2–4.5 mm, densely hairy, at apex with a beak up to 1.5 cm long, glabrous for 0–2 mm in basal part, in upper part with long hairs up to 4.5 cm long.
Strophanthus speciosus flowers towards the end of the dry and the beginning of the rainy season. Mature fruits occur throughout the year, with a peak in the dry season.
Strophanthus comprises 38 species, of which 30 occur in continental Africa, 1 in Madagascar and 7 in Asia, from India to South-East Asia. Some other species are used in southern Africa for similar purposes as Strophanthus speciosus. The latex of Strophanthus gerrardii Stapf from southern Mozambique, north-eastern South Africa and Swaziland is used as a spear poison, whereas a fruit in decoction is taken to treat hysteria. Strophanthus luteolus Codd from southern Mozambique and north-eastern South Africa has the same uses.
Ecology
Strophanthus speciosus occurs in forest, often at margins, at (300–)900–1500 (–1800) m altitude.
Genetic resources and breeding
Like most Strophanthus species from the forest, Strophanthus speciosus is not common in its distribution area, although not in danger of genetic erosion.
Prospects
In traditional medicine Strophanthus speciosus is only used to treat snakebites. It will remain of minor importance, unless the effectivity against snake poison is confirmed by research.
Major references
• Beentje, H.J., 1982. A monograph on Strophanthus DC. (Apocynaceae). Mededelingen Landbouwhogeschool Wageningen 82–4. Wageningen, Netherlands. 191 pp.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• van Wyk, B.E., van Heerden, F. & van Oudtshoorn, B., 2002. Poisonous plants of South Africa. Briza Publications, Pretoria, South Africa. 288 pp.
• 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.
Other references
• Arnold, T.H., Prentice, C.A., Hawker, L.C., Snyman, E.E., Tomalin, M., Crouch, N.R. & Pottas-Bircher, C., 2002. Medicinal and magical plants of southern Africa: an annotated checklist. Strelitzia 13. National Botanical Institute, Pretoria, South Africa. 302 pp.
• Schindler, O. & Reichstein, T., 1952. Identifizierung von Substanz Nr. 763 aus Strophanthus speciosus und S. boivinii als Strospesid (Desgluco-digitalinum-verum). Glykoside und Aglykone, 93. Mitteilung. Helvetica Chimica Acta 35(2): 442–446.
Author(s)
• A. de Ruijter
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, Rιduit, 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

Correct citation of this article:
de Ruijter, A., 2006. Strophanthus speciosus (N.B.Ward & Harv.) Reber. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes mιdicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.