Prota 11(1): Medicinal plants/Plantes médicinales 1
Pflanzenw. Ost-Afrikas: 141 (1895).
2n = 14
Origin and geographic distribution
Aloe volkensii occurs in Rwanda, southern and coastal Kenya, southern Uganda, and northern and coastal Tanzania, including Zanzibar.
In eastern Africa the leaf sap of Aloe volkensii is applied to burns, wounds and sores and as a lotion to eyes. The bitter exudate is applied to nipples to wean children and is rubbed on the forehead to treat headache. In Rwanda it is taken as a purgative. The leaf sap is taken to expel a retained placenta. The leaves are used to deworm livestock. Small amounts of leaf sap are added to butter to increase its shelf life. Aloe volkensii is planted as a live fence. Roots are used to accelerate the fermentation of honey beer and to impart a slightly bitter taste.
Exudate of Aloe volkensii contains a mixture of the stereoisomers aloin A (barbaloin) and aloin B (isobarbaloin), which are responsible for the laxative properties.
Succulent shrub or small tree up to 3(–9) m tall; stem solitary or clustered, up to 30 cm in diameter, simple or branching from above the base, with persistent dead leaves. Leaves in a rosette, erect, later spreading and recurved; stipules absent; petiole absent; blade narrowly lanceolate, up to 1 m × 10 cm, margin with forward pointing, brown-tipped teeth 2–4 mm long, 1–2.5 cm mm apart, blade dull olive-green; exudate yellow, drying red. Inflorescence consisting of head-like racemes c. 8 cm long, becoming cylindrical-conical; peduncle 50–60(–85) cm long, with 8 or more spreading branches, lowest with secondary branches; bracts broadly ovate, 2–5 mm long. Flowers bisexual, regular, 3-merous; pedicel 1–1.5 cm long; perianth tubular, 2.5–3.5 cm long, 6–8 mm in diameter, lobes 6, 12–17 mm long, red with yellow tips; stamens 6, exserted; ovary superior, 3-celled, style filiform, stigma head-shaped, exserted. Fruit an ovoid capsule c. 3 cm × 1.5 cm, dehiscing loculicidally, many-seeded. Seeds c. 9 mm long, broadly winged.
Aloe comprises about 450 species in Africa and Arabia, of which c. 315 occur in mainland Africa, c. 100 are endemic to Madagascar or the Indian Ocean islands (including the former Lomatophyllum) and c. 50 occur in Arabia. Aloe volkensii belongs to a group of species, which are often small trees with usually unbranched trunks (sometimes branching at base) or suckering shrubs. Several other species in this group have medicinal uses. Aloe ballyi Reynolds is a rare species from Kenya and Tanzania. Leaf sap is taken as a purgative but this is dangerous as it contains poisonous alkaloids. It is planted as an ornamental in the streets of Nairobi, Kenya. Aloe christianii Reynolds occurs in DR Congo, Tanzania and a large part of southern Africa. A leaf infusion is taken to induce abortion, but is considered too poisonous in Zimbabwe. Aloe excelsa A.Berger occurs in a large part of southern Africa. An infusion made of the leaves is taken as a malaria prophylactic and to cure stomach-ache, asthma and jaundice and is put in drinking water of chickens to prevent diseases. The leaves contain aloesin, anthraquinones and a C-glucoside. In Namibia the leaf sap of Aloe littoralis Baker is applied to cure eye problems and to arrest progress of venereal disease. Powdered leaves are an effective anti-inflammatory. Daily use of leaf extract is said to be effective as a malaria prophylaxis. Chopped leaves, boiled in water are purgative both for humans and livestock. Chopped leaves added to drinking water protect cattle against ticks and ear lice and chickens against lice. Aloe marlothii A.Berger occurs in Botswana, Mozambique, Swaziland and northern South Africa. A leaf decoction is taken with porridge to treat stomach-ache and intestinal worms. The leaf pulp is rubbed on nipples to wean children. The burned dried leaves are mixed with snuff. Aloe marlothii is planted as a live fence. The leaves show strong in-vitro anthelminthic activity. Ash from the leaves, mixed with maize, effectively protects the latter from storage pests. The dried exudate was formerly traded under the name ‘Natal aloe’. Aloe marlothii is an important bee plant.
Aloe volkensii occurs in dry, riverine forest and bush on rocky localities from sea-level to 2100 m altitude.
Cuttings are used to establish live fences of Aloe volkensii. For medicinal use leaves are primarily harvested from wild plants in a non-destructive way.
Genetic resources and breeding
There is no indication of over-utilisation of Aloe volkensii in its natural range.
Aloe volkensii has not drawn much interest so far. It is likely to remain important only for local use. Its habit does not make it a likely candidate for domestication.
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Correct citation of this article:
Bosch, C.H., 2006. Aloe volkensii Engl. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.