Prota 2: Vegetables/L้gumes
Kew Bull. 15(3): 346 (1962).
n = 11
Cucumis naudinianus Sond. (1862), Citrullus naudinianus (Sond.) Hook.f. (1871), Colocynthis naudianus (Sond.) Kuntze (1891).
Herero cucumber, gemsbok cucumber, wild melon (En).
Origin and geographic distribution
Acanthosicyos naudinianus is native to Zambia, Angola, Namibia, Botswana, Zimbabwe, Mozambique and South Africa.
The mature fruits of Acanthosicyos naudinianus are eaten raw or roasted; unripe fruits cause a burning sensation of the tongue and lips when eaten raw. The fruit also provides an important source of water. The fruit skin and the seeds are roasted and pounded to make a meal. The tuberous roots are considered inedible or even poisonous and in Zambia they have been reportedly used for homicidal purposes. The preparation and use of arrow poison made from the roots of Acanthosicyos naudinianus is widespread among bushmen tribes in Angola, Namibia and Botswana.
Some Acanthosicyos naudinianus plants produce bitter fruits. The bitter taste is attributed to cucurbitacin B (c. 0.001%). Fruits contain per 100 g:: water 90.6 g, energy 111 kJ (27 kcal), protein 1.3 g, fat 0.2 g, carbohydrate 4.8 g, fibre 2.1 g, Ca 21 mg, Mg 23 mg, P 25 mg, Fe 0.5 mg, thiamin 0.09 mg, riboflavin 0.03 mg, niacin 0.98 mg and ascorbic acid 35 mg (Arnold, T.H., Wells, M.J. & Wehmeyer, A.S., 1985). The seed kernel yields c. 15% thin, yellow non-drying oil, and the residue contains c. 20% protein. In the older roots the total content of cucurbitacins amounts to 1.4%. Cucurbitacins, which are also known from other Cucurbitaceae and various other plant species, exhibit cytotoxicity (including antitumour activity) and anti-inflammatory and analgesic activities.
Perennial, dioecious, scandent herb with solitary, spiniform tendrils; root tuberous, up to 1 m long; stem annual, up to 6 m long, rooting at the nodes, glabrescent. Leaves alternate, simple; stipules absent; petiole 0.77.5 cm long; blade ovate to broadly ovate in outline, usually deeply palmately 5-lobed, 318 cm ื 2.514 cm. Flowers solitary, unisexual, 5-merous; petals yellow to white, 1.42.5 cm ื 0.91.3 cm; male flowers with pedicel up to 2 cm long, receptacle campanulate, up to 6 mm long, pale green, sepals up to 6 mm ื 1.5 mm, stamens 3 or 5; female flowers with pedicel up to 8 cm long, receptacle cylindrical, 3 mm long, sepals 34 mm long, 3 small staminodes, ovary inferior, spiny. Fruit an ellipsoid or subglobose berry 612 cm ื 48 cm, weight c. 250 g, fleshy, covered with seta-tipped fleshy spines, many-seeded. Seeds ellipsoid, slightly compressed, 7.510 mm ื 46 mm.
Acanthosicyos comprises 2 species and is placed in the tribe Benincaseae together with important genera such as Benincasa, Coccinia, Citrullus, Lagenaria and Praecitrullus. The better known nara melon (Acanthosicyos horridus) differs notably from Acanthosicyos naudinianus by its shrubby habit and leafless, spiny stems, and is restricted to Angola, Namibia and South Africa.
Elephants feed on the fruits and may play an important role in the dispersal of seeds.
Acanthosicyos naudinianus is a typical Kalahari species which prefers deep sandy soils. It occurs in woodland, wooded grassland and grassland at altitudes of 9001350 m. It is not frost tolerant but tolerates a saline subsoil.
The fruits of Acanthosicyos naudinianus are exclusively collected from the wild.
Genetic resources and breeding
There is no indication that Acanthosicyos naudinianus is threatened. As in many other cucurbits there is considerable variation in the bitterness of the fruits. This will allow for selection and breeding of more palatable lines. There are 4 documented accessions held in the United States and 2 at the Royal Botanic Gardens Kew (United Kingdom).
In view of increasing demands for edible oil and protein in arid lands, Acanthosicyos naudinianus is a candidate for development as a high-yielding, dry country crop. It yields a crop quickly, harvesting the fruits is easy, it has a wide ecological adaptation, it is easily propagated and handled, and fruits store well. As such, it compares favourably with Acanthosicyos horridus as a candidate for domestication.
Arnold, T.H., Wells, M.J. & Wehmeyer, A.S., 1985. Khoisan food plants: taxa with potential for future economic exploitation. In: Wickens, G.E., Goodin, J.R. & Field, D.V. (Editors). Plants for arid lands. Proceedings of the Kew International Conference on Economic Plants for Arid Lands. Allen & Unwin, London, United Kingdom. pp. 6986.
Jeffrey, C., 1978. Cucurbitaceae. In: Launert, E. (Editor). Flora Zambesiaca. Volume 4. Flora Zambesiaca Managing Committee, London, United Kingdom. pp. 414499.
Jeffrey, C., 1980. A review of the Cucurbitaceae. Botanical Journal of the Linnean Society 81: 233247.
Neuwinger, H.D., 1996. African ethnobotany: poisons and drugs. Chapman & Hall, London, United Kingdom. 941 pp.
SEPASAL, 2003. Acanthosicyos naudinianus. [Internet] Survey of Economic Plants for Arid and Semi-Arid Lands (SEPASAL) database. Royal Botanic Gardens, Kew, United Kingdom. http://www.rbgkew.org.uk/ceb/sepasal/acantho.htm. Accessed 24 February 2003.
Dudley, J.P., 2000. Seed dispersal by elephants in semiarid woodland habitats of Hwange National Park, Zimbabwe. Biotropica 32(3): 556561.
Jeffrey, C., 1962. Notes on Cucurbitaceae, including a proposed new classification of the family. Kew Bulletin 15(3): 337371.
Jeffrey, C., 1979. The economic potential of some Cucurbitaceae and Compositae of tropical Africa. In: Kunkel, G. (Editor). Taxonomic aspects of African economic botany. Proceedings of the 9th plenary meeting of AETFAT. Las Palmas, Gran Canaria, Spain. pp. 3538.
Meeuse, A.D.J., 1962. The Cucurbitaceae of southern Africa. Bothalia 8(1): 1112.
Schrire, B.D., 1987. Cucurbitaceae, orthographic ambiguity clarified. Bothalia 17(2): 181.
van Wyk, B.E. & Gericke, N., 2000. Peoples plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria, South Africa. 351 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:
Bosch, C.H., 2004. Acanthosicyos naudinianus (Sond.) C.Jeffrey In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/L้gumes. [CD-Rom]. PROTA, Wageningen, Netherlands.