Prota 11(1): Medicinal plants/Plantes médicinales 1
A.DC., Prodr. 15(2.2): 1219 (1866).
Excoecaria sylvestris S.Moore (1911).
Milky mangrove, red ears (En).
Origin and geographic distribution
Excoecaria madagascariensis occurs from Somalia south to Tanzania, and also in Zimbabwe, northern South Africa, Swaziland and Madagascar.
In Kenya the Giriama and Teita people use the plant sap in the preparation of hunting arrow poison, often in combination with the latex of Acokanthera schimperi (A.DC.) Schweinf. and the tuber of Dioscorea quartiniana A.Rich. The sap causes painful blisters when it touches the skin. The plants are very toxic to cattle and camels.
The wood is used as firewood and for charcoal production and also to make tool handles.
No chemical or pharmacological analyses have been carried out for Excoecaria madagascariensis, but several highly toxic alkaloids (excoecarins) and phorbol esters have been reported in other Excoecaria species.
Monoecious glabrous shrub or small tree up to 4(–7) m tall; bark rough or smooth, with colourless or milky latex. Leaves opposite, simple and entire; stipules triangular-ovate, c. 2.5 mm long, soon falling; petiole up to 1 cm long, channeled above; blade elliptical, elliptical-oblong to elliptical-oblanceolate, 4–17 cm × 2–6 cm, base cuneate, apex obtuse to emarginate, glossy and dark green above, reddish brown when young. Inflorescence an axillary spike in the upper leaf axils, 2–3 cm long, with only male flowers or with some female flowers at base. Flowers unisexual, regular, sessile, petals absent, disk absent; male flowers with 3 lanceolate sepals c. 0.5 mm long, acute, toothed, pale yellow-green or whitish, stamens 3, c. 1 mm long; female flowers with 3 rounded to ovate sepals c. 0.5 mm long, obtuse, toothed, ovary superior, 3-lobed, smooth, 3-celled, styles 3, fused at base, recurved. Fruit a 3-lobed capsule c. 1 cm in diameter, smooth, green, turning red or yellowish, 3-seeded. Seeds globose, c. 4 mm in diameter, smooth, greyish brown, mottled.
Excoecaria occurs in the Old World tropics and Pacific islands and comprises 35 species; about 6 species occur in continental Africa and about 5 in Madagascar. Formerly, many Excoecaria species were included in Sapium, which is now considered to be native only to the New World. Excoecaria bussei (Pax) Pax occurs in southern Africa. A root decoction is taken as an emetic. The plant sap is considered poisonous, and cattle do not browse the plant. Sometimes the seeds are chewed; they are tasteless at first but later produce a peppery, burning sensation, which lasts a long time. Most people consider them poisonous. The latex of Excoecaria benthamiana Hemsl. (‘bois charlot’, ‘bois jasmin rouge’), a rare endemic of the Seychelles, is a powerful vesicant and is applied externally to warts.
Excoecaria madagascariensis occurs in thickets and evergreen forest, often on sandy soils along rivers, from sea-level up to 1850 m altitude.
Excoecaria madagascariensis can be propagated through wildlings and cuttings. It is moderately fast growing and can be pruned and pollarded.
Genetic resources and breeding
Excoecaria madagascariensis is locally common in East Africa and Madagascar, but in Swaziland there are indications that it is at risk of genetic erosion because of forest clearing and invasion of alien plants, such as Chromolaena odorata (L.) R.King & H.Rob. and Melia azedarach L.
The latex of Excoecaria madagascariensis is very poisonous, but nothing is known about its chemical properties. As other Excoecaria species yield chemical compounds with interesting pharmacological activities, more research is warranted. Excoecaria madagascariensis is also considered a useful indicator of underground water and could be applied for soil erosion control in riparian areas.
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Correct citation of this article:
Bethwell, O.O., 2008. Excoecaria madagascariensis (Baill.) Müll.Arg. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.