Prota 2: Vegetables/Légumes
DC., Prodr. 8: 665 (1844).
Asclepiadaceae (APG: Apocynaceae)
2n = 22
Hoodia lugardii N.E.Br. (1903), Hoodia macrantha Dinter (1914), Hoodia gibbosa Nel (1937), Hoodia montana Nel (1937).
Ghaap, hoodia cactus (En).
Origin and geographic distribution
Hoodia currorii is found in Namibia and Angola (subsp. currorii), and in Botswana and southern Zimbabwe (subsp. lugardii (N.E.Br.) Bruyns).
Stems are broken or cut off, rubbed on a stone to remove the spines, cut into strips and these strips are eaten. They have a peculiar pervasively spreading sweet taste which is remarkably persistent and is said to quench thirst and hunger for extended periods. They also make a tasty preserve. Young pods are much sought after for their sweetness. Stems that have swelled after recent rains are preferred. Sometimes they are taken home to be soaked in water before being eaten. It is also said that after eating, an interesting liquorice-like aftertaste remains which gives tobacco smoke a particularly pleasant taste.
For thousands of years, African tribesmen in South Africa, Botswana, Namibia and Angola have eaten Hoodia to stave off hunger and thirst on long hunting trips. Hoodia has recently attracted the interest of the Western drug industry. The Council for Scientific and Industrial Research in South Africa has identified the active principle of Hoodia and patented it. In 2001 they passed on their findings to a British firm, which patented the appetite-suppressing ingredient in Hoodia, on the basis of its potential as a slimming drug. This firm sold the rights to license the drug to a United States pharmaceutical company, which hoped to have the treatment ready in pill form within 3 years. The San, an African tribe, considered this situation to be bio-piracy because the knowledge has been taken from them without paying proper compensation. The International Intellectual Property Institute, Washington, United States was the intermediary in this matter. In 2003 an agreement was reached between the San and the pharmaceutical company: the San will receive 1.5 million US$ per year for a period of 4 years while the drug is being developed and as soon as the medicine is marketed they will receive 6% of the royalties.
Other traditional medicinal applications mentioned are to treat indigestion, hypertension, diabetes, haemorrhoids and stomachache. Most Hoodia species are attractive and unusual ornamentals for desert gardens.
Spiny succulent shrub up to 1 m tall, with many erect to spreading, branching stems; stem cylindrical, 4–8 cm in diameter, grey-brown-green, with 11–24 vertical ribs consisting of prominent obtuse tubercles each one tipped with a sharp spine 6–10 mm long. Flowers arising in groups of 1–4 near the apex of the stem, opening successively, bisexual, regular, 5-merous; pedicel 1–6 cm long; sepals ovate-lanceolate, 4–8 mm × 3 mm; corolla saucer-shaped, consisting of a short pentagonal tube 3–6 mm × 6–9 mm, and a subcircular to clearly lobed limb 4–18 cm in diameter, outside pale red and glabrous, inside deep red or yellowish-pink and covered with pink to purple hairs 3–4 mm long, lobes broadly ovate, ending in a narrow point up to 2 cm long; corona deep red-purple or red-brown, outer corona forming a cup with bifid lobes, inner corona with linear lobes, incumbent on the backs of the anthers and mostly exceeding them to meet in the centre. Fruit a pair of fusiform, horn-like follicles, each follicle 15–22 cm long, glabrous, pink to green, 100–250-seeded. Seeds with a tuft of straight, simple hairs (coma) 15–25 mm long.
Hoodia currorii is very variable and has been divided into 2 subspecies: subsp. currorii (corolla 5–17 cm in diameter, pedicel longer than 12 mm, occurring in Angola and Namibia) and subsp. lugardii (N.E.Br.) Bruyns (corolla 4–7.5 cm in diameter, pedicel shorter than 7 mm, occurring in Botswana and Zimbabwe).
Hoodia comprises 13 species, and the related Lavrania comprises 5 species. Lavrania differs from Hoodia by the tubercles on the stems: in Hoodia they are tipped with a spine 3–12 mm long which is initially green, drying out to grey-brown and base not depressed into apex of tubercle; in Lavrania the tubercles are tipped with a small conical persistent leaf less than 1 mm long, remaining grey-green, not drying out, usually sunken into the apex of the tubercle.
The stems of many other Hoodia species are eaten, although there are differences in flavour (more or less bitter). They form a convenient emergency food and moisture source in harsh arid environments. Other recorded edible species are: Hoodia alstonii (N.E.Br.) Plowes (Namibia, South Africa), Hoodia flava (N.E.Br.) Plowes (Namibia, South Africa), Hoodia gordonii (Masson) Sweet ex Decne. (Namibia, South Africa), Hoodia officinalis (N.E.Br.) Plowes (Namibia, South Africa) and Hoodia pilifera (L.f.) Plowes (South Africa). They are all commonly known as ‘ghaap’. The young pods of all species are liked for their sweetness. Lavrania species are never eaten; they have an extremely strong, bitter taste and are widely (probably falsely) considered poisonous.
The primary stem of seedlings of Hoodia currorii grows vertically up from between the cotyledons and after it has reached some size, axillary buds near the base give rise to secondary shoots. After a few years, when the plant is about 20 cm tall, flowering starts near the apex of the main stem and branches. After flowering, vegetative growth continues and in subsequent years new flushes of flowers appear in the higher portion of the stem. Most Hoodia flowers have a foetid, excrement-like odour; they produce nectar and pollination is mostly effected by flies.
In Angola Hoodia currorii subsp. currorii is restricted to the very arid parts of the coastal Namib Desert; in Namibia it also occurs in this arid zone and also eastward (up to 250 km from the coast), e.g. in dry, short forest and in dry Acacia scrub vegetation. Subsp. lugardii is found further east than any other Hoodia species, growing on calcareous soil, often forming a shrub around the base of Acacia tortilis (Forssk.) Hayne or Colophospermum mopane (Benth.) J.Léonard.
Almost all Hoodia species can be propagated by seed and by cuttings taken from the base of a branch. Cultivation is not easy because of the need for hot and dry conditions. Cultivated plants usually die because of a too moist growing medium and a lack of fresh air. A recommended medium is 1 part clay, 3 parts humus-rich soil and 4 parts rough sand or gravel.
Genetic resources and breeding
As a consequence of the general degradation of vast parts of southern Africa through overgrazing by sheep and goats, Hoodia species have practically disappeared in some areas where they were formerly abundant. All species are now protected by CITES regulations and some species are in danger of extinction.
Hoodia currorii and other Hoodia species cannot be recommended as a vegetable from the wild because of the danger of extinction. The nutritive value should be investigated further and commercial cultivation possibilities need more research. Possibly, the ornamental and medicinal values far exceed other commercial prospects, making large-scale commercial cultivation an interesting option. As a suppressant of appetite and thirst, the active principle of Hoodia seems to have a bright future.
• Bruyns, P.V., 1993. A revision of Hoodia and Lavrania (Asclepiadaceae – Stapelieae). Botanische Jahrbücher 115: 145–270.
• Plowes, D.C.H., 1992. A preliminary reassessment of the genera Hoodia and Trichocaulon (Stapelieae: Asclepiadaceae). Asklepios 56: 5–15.
• White, A. & Sloane, B.L., 1937. The Stapelieae. 3 volumes. 2nd Edition. Pasadena, California, United States. 1186 pp.
• Albers, F. & Austmann, M., 1987. Asclepiadaceae. In: Löwe, A. (Editor). IOPB Chromosome reports. Taxon 36: 494–496.
• Noltee, F. & de Graaf, A., 1983. Hoodia currorii (Hooker) Decaisne. Succulenta 62(2): 26–29.
• van Wyk, B.E., van Oudtshoorn, B. & Gericke, N., 1997. Medicinal plants of South Africa. Briza Publications, Pretoria, South Africa. 304 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.
Correct citation of this article:
Jansen, P.C.M., 2004. Hoodia currorii (Hook.) Decne. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.