Prota 11(1): Medicinal plants/Plantes médicinales 1
Journ. Linn. Soc., Bot. 38: 238 (1908).
Origin and geographic distribution
Aloe wollastonii is distributed from north-eastern DR Congo to western Kenya and Tanzania.
In DR Congo and Burundi exudate, crushed leaves and dried leaves are applied topically to cure haemorrhoids. In Uganda itchy skin rash is treated by bathing in an infusion of Aloe wollastonii leaves or by using the crushed leaves as a sponge. Uterine inflammation is treated by drinking an infusion of the leaves. A decoction of roots and leaves is drunk to cure jaundice. Veterinary applications of the leaves are multiple in DR Congo, Rwanda and Burundi. Anthrax, piles, burns, parasites and retention of the afterbirth are ailments that are treated with fresh leaves or dried leaf powder, as is East Coast fever in cattle.
Aloe species contain a variety of phenolic compounds, including chromone, anthraquinone or anthrone derivatives. The leaf exudate of Aloe wollastonii contains about 15% aloin.
Succulent perennial herb up to 1.5 m tall, without stem, usually solitary. Leaves 12–15 in a dense rosette, erect to spreading; stipules absent; petiole absent; blade lanceolate, up to 50 cm × 10 cm, apex long-acuminate, margin with sharp white-horny to red-brown teeth 4–6 mm long, 1–2 cm apart, blade dull green with elongated white blotches in transverse bands; exudate drying yellow. Inflorescence consisting of cylindrical-conical racemes 10–25(–30) cm long, laxly flowered; peduncle up to 1.2 m long, with 4–6 branches, lower branches sometimes rebranched; bracts linear–lanceolate, (10–)15–20 mm long. Flowers bisexual, regular, 3-merous; pedicel 1.5–2 cm long; perianth tubular, 3–3.5 cm long, c. 9 mm in diameter at base, lobes 6, c. 11 mm long, pinkish to orange-red, rarely yellow; stamens 6, exserted; ovary superior, 3-celled, style filiform, stigma head-shaped, exserted. Fruit an ovoid capsule c. 20 mm × 12 mm, dehiscing loculicidally, many-seeded. Seeds c. 3 mm × 5 mm, blackish brown with broad, speckled wings.
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 wollastonii has been confused in the literature with Aloe lateritia Engl., a species with a more eastern distribution and more densely flowered racemes. Aloe wollastonii belongs to a group of Aloe species with solitary rosettes or forming small groups, with leaves wider than 2 cm and inflorescences with at least 2 branches. Several other species in this group have medicinal uses. The exudate of Aloe citrina S.Carter & Brandham is used in Somalia to cure ophthalmia. The leaf juice of Aloe cryptopoda Baker is used in Zimbabwe to treat constipation, venereal diseases and as abortifacient, although the abortifacient activity of the infusion could not be demonstrated in tests with rats. The sap from roasted leaves of Aloe kilifiensis Christian from coastal Kenya is applied to the skin to reduce swelling. A decoction of the leaves is taken to cure an enlarged spleen. The exudate is used externally to treat headache. Aloe rivae Baker from Ethiopia and Kenya is threatened because of overexploitation for undocumented medicinal uses. In Sudan both the leaves and leaf exudate of Aloe sinkatana Reynolds are valued for treating a variety of ailments, including skin diseases, constipation, fever, tonsillitis, haemorrhoids and inflamed colon. Aloe sinkatana is valued as an ornamental. It is depleted in the wild and propagation and conservation measures are urgently needed.
Aloe wollastonii is found in grassland and woodland at 1100–2300 m altitude.
Genetic resources and breeding
Aloe wollastonii is widespread and probably not under direct threat of genetic erosion or extinction, although it is included in CITES lists like all Aloe spp. except Aloe vera (L.) Burm.f.
As Aloe wollastonii produces few or no suckers it is not an obvious choice for commercial cultivation. Confusion with Aloe lateritia warrants review of the literature on chemistry and ethnobotany of both species.
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Correct citation of this article:
Bosch, C.H., 2006. Aloe wollastonii Rendle. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.