Merremia kentrocaulos (PROTA)
Merremia kentrocaulos (C.B.Clarke) Hallier f.
- Protologue: Oliv., Fl. Trop. Afr. 4(2): 103 (1905).
- Family: Convolvulaceae
- Rough-stemmed morning-glory (En).
Origin and geographic distribution
Merremia kentrocaulos occurs from Senegal eastward to Somalia and southwards to South Africa. It is also found in tropical Asia, Australia and the Pacific.
In Senegal a decoction of the whole plant, together with Pericopsis laxiflora (Benth.) Meeuwen, is drunk to treat ailments of the liver and gall bladder. In Tanzania a decoction of the roots is drunk against fever.
Merremia kentrocaulos contains numerous aromatic 3α -acyloxytropanes, such as convolamine (3α-veratroyloxytropane) and phyllalbine (3α -vanilloyloxytropane). Four ipomeamarone-like furano-sesquiterpenes, merrekentrones A, B, C and D have been isolated from the roots. Some of these compounds are interesting because of their structural closeness to compounds with fungicidal activity.
- Large, almost glabrous, twining perennial with tuberous rootstock.
- Older stems woody, younger stems herbaceous, terete, with reddish papillae.
- Leaves alternate or spirally arranged, simple; petiole 3–7 cm long; blade pentagonal in outline, 4–13 cm long and wide, palmately dissected nearly to the base, base cordate; lobes 5–7, elliptical, lanceolate or oblong-lanceolate, up to 6.5 cm × 2 cm, acute.
- Inflorescence an axillary, 1–few-flowered cyme; peduncle almost erect, 3–8 cm long; bracteoles ovate, early deciduous.
- Flowers bisexual, regular, 5-merous; pedicel up to 3 cm long, at first deflexed, almost erect when the flowers open and nodding in fruit; sepals ovate-oblong, up to 3 cm long, apex obtuse, glabrous, concave, somewhat unequal, enlarging in fruit; corolla funnel-shaped, 3.5–5.5 cm long, yellow or white with dark purple centre, glabrous, limb faintly pentagonal, plicate, lobes bluntly triangular; stamens included; ovary superior, 2–4-celled, style simple, filiform, stigma biglobular.
- Fruit a narrowly ellipsoid capsule, 1.2–1.6 cm long, at first enclosed in the accrescent, brown and coriaceous calyx, exposed just before dehiscence when sepals spread out, pale brown.
- Seeds 6–8 mm long, brown to black, minutely hairy.
Other botanical information
Merremia comprises about 80 species throughout the tropics. It is closely related to Ipomoea differing essentially by having smooth pollen. Some authors recognize 2 varieties in Merremia kentrocaulos: the typical variety with entire or minutely crenulate leaf lobes, and var. pinnatifida N.E.Br. with deeply pinnatifid leaf lobes. Merremia kentrocaulos is sometimes confused with Merremia tuberosa (L.) Rendle, a native of the Americas, occurring and often naturalized in tropical Asia, and southern and eastern Africa and Madagascar.
Several other Merremia species are used medicinally in tropical Africa.
Merremia dissecta (Jacq.) Hallier f. is a perennial, slender twiner, with white flowers with a rosy purple throat, originally from the Americas, but now widely distributed in the warmer parts of the world. The plant has numerous medicinal uses in various parts of the world. In Nigeria an infusion of the leaves is a major ingredient of snake-bite medicines internally taken or externally applied. An infusion of the leaves is taken as a sedative for chest complaints. It is sometimes planted as an ornamental. In Nigeria, the plant is reported to keep snakes away from houses where it is grown. Because of their smell the leaves of Merremia dissecta are used to flavour liqueurs in India.
Merremia gorinii Chiov. is a perennial creeper or twiner with yellowish to orange-red flowers with darker centre. It occurs in the Horn of Africa and Kenya. In Somalia the root is used as suppository against haemorrhoids.
Merremia hederacea (Burm.f.) Hallier f. is a twining or creeping herb with yellow or white flowers, occurring in tropical Asia, Australia and some Pacific islands. In Africa it occurs dispersed from Senegal to Somalia and southward to Mozambique, Madagascar and the Mascarene islands. In Burkina Faso the plant is used along with Sclerocarya birrea Hochst. in fortune-telling. In India it is commonly used to treat colds, fever, sunstroke, laryngitis and leucorrhoea. The seeds are used to treat fevers, colds, sore throats, haematuria, conjunctivitis and boils. Leaves are made into a poultice with turmeric and broken rice to apply to chapped hands and feet. In Kordofan (Sudan) the long slender stems are used to tie loads to saddles of pack animals. Stock will graze it. It is worthy of cultivation because of its beautiful flowers.
Merremia peltata (L.) Merr. is a large liana with white or yellow flowers, with a pantropical distribution, especially the Old World tropics. In Africa it occurs in the Indian Ocean islands. In Madagascar the plant sap is given to small children to ease breathing. It is also taken against diarrhoea and intestinal worms. It is planted as an ornamental because of its flowers and unusual leaves. The tuber can be cooked and eaten but it is considered purgative as well.
Merremia tuberosa (L.) Rendle is a robust twiner, native of the tropical Americas and cultivated for its ornamental flowers in West Africa and other tropical countries. The woody fruits can be used in dry flower arrangements. The tuber is a drastic purgative and has been used as an adulterant for ‘jalap resin’ obtained from Ipomoea dumosa (Benth.) L.O.Williams in Central America.
Merremia umbellata (L.) Hallier f., called ‘hogvine’ in English, is a perennial ornamental twiner with bright yellow or white flowers occurring throughout the tropics. There are 2 subspecies: subsp. umbellata occurs in West Africa and the Americas, and subsp. orientalis (Hallier f.) Oostr. occurs in eastern Africa and Asia. In Asia the leaves made into poultices are applied to festering wounds and burns and the root is used as laxative. Also in Asia the young leaves are eaten as a vegetable. In Ghana the plant acts as sand-binder on beaches.
Merremia xanthophylla Hallier f. is a polymorphic herb with prostrate or trailing stems and pale yellow to whitish flowers. Its distribution is incompletely known but includes Sudan, Ethiopia, Zambia and Zimbabwe. In Sudan a root extract is drunk against convulsions.
Merremia kentrocaulos grows in open forest, e.g. in dry mopane- Acacia scrub or woodland, and in savanna on sandy or rocky soils from sea-level up to 1300 m altitude. It is sometimes a weed in rice fields.
Propagation and planting
Merremia kentrocaulos is propagated by seed.
Merremia kentrocaulos is widespread and not in danger of genetic erosion.
A comprehensive review of Merremia and related genera is wanted. Merremia kentrocaulos is likely to remain locally of some medicinal value. More research is needed to evaluate the phytochemical compounds isolated from the plant.
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- Gryparis, C., Lykakis, I.N., Efe, C., Zaravinos, I.-P., Vidali, T., Kladou, E. & Stratakis, M., 2011. Functionalized 3(2H)-furanones via photooxygenation of (ß-keto)-2- substituted furans: application to the biomimetic synthesis of merrekentrone C. Organic and Biomolecular Chemistry 9(16): 5655–5658.
- Jenett-Siems, K., Siems, K., Witte, L. & Eich, E., 2001. Merrekentrones A-D, ipomeamarone-like furanosesquiterpenes from Merremia kentrocaulos. Journal of Natural Products 64(11): 1471–1473.
- Jennet-Siems, J.K., Weigl, R., Böhm, A., Mann, P., Tofern-Reblin, B., Ott, S.C., Ghomian, A., Kaloga, M., Siems, K., Witte, L., Hilker, M., Müller, F. & Eich, E., 2005. Chemotaxonomy of the pantropical genus Merremia (Convolvulaceae) based on the distribution of tropane alkaloids. Phytochemistry 66: 1448–1464.
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- L.P.A. Oyen, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Correct citation of this article
Oyen, L.P.A., 2013. Merremia kentrocaulos (C.B.Clarke) Rendle. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(2): Medicinal plants/Plantes médicinales 2. PROTA, Wageningen, Netherlands. Accessed 14 June 2021.
- See this page on the Prota4U database.