Hypoxis hemerocallidea
Fisch., C.A.Mey. & Avé-Lall.

Family : Hypoxidaceae (Star lily family)
Common names : star flower, yellow star (Eng.); sterblom, gifbol (Afr.); moli kharatsa, lotsane (S Sotho); iNkomfe (Zulu). Wrongly referred to as African potato.

Hailed as‘miracle muti' and ‘wonder potato', Hypoxis hemerocallidea has been very much in the limelight during the past two decades and is today surrounded by controversy. It is a beautiful tuberous perennial, synonymous with the grasslands, where its yellow star-like flowers herald the arrival of spring and summer rains.

Description
Tuberous perennial with straplike leaves and yellow star-shaped flowers. The leaves are up to 400 mm long, neatly arranged one above the other in 3 ranks, broad, stiff and arching outwards with prominent ribs and tapering towards the tips. The lower surface of the leaves is densely hairy with white hairs. Leaves appear above ground in spring before the flowers.

Hypoxis hemerocallidea plant

The flowers are carried on 5 or 6 slender erect inflorescences, each carrying 5–13 bright yellow, star-shaped flowers with 6 tepals. Six free stamens arise from the base of the tepals with prominent anthers. The style is short and fat, carrying the robust stigma.

The flowers are short-lived and close at midday. Flowers open sequentially from the base to the apex. Usually 1–3 flowers are open at the same time, thus encouraging cross-pollination.

Hypoxis hemerocallidea flower and buds

The large dark brown tuber is covered with bristly hairs, and is bright yellow when freshly cut. It has an unpleasant bitter taste.

Seeds are hard, black, smooth and glossy.

Conservation status
H. hemerocallidea is not listed as a threatened plant in the Red Data plant list. However the natural grasslands in the urban metropolitan areas are under extreme pressure because of urban sprawl. Many plants, including related species, are also dug up due to their popularity as a medicinal remedy. Since the plants do not re-seed easily, the demand for the tubers may cause the plants in the wild to decline.

Distribution and habitat
H. hemerocallidea occurs in open grassland and woodland and is widespread in South Africa in the eastern summer rainfall provinces (Eastern Cape, Free State, KwaZulu-Natal, Mpumalanga, Gauteng and Limpopo). It also occurs in Botswana, Lesotho and Swaziland.

Derivation of name and historical aspects
The name Hypoxis was given by Linnaeus in 1759and was derived from the Greek words hypo (below) and oxy (meaning sharp), in reference to the ovary which is pointed at the base.

The specific epithet is derived from the Greek hemera (a day) and kallos (beauty), presumably referring to the flowers which are short-lived and resemble the day lily Hemerocallis.

It is suggested that the incorrectly used name ‘African Potato' was introduced by the media in early 1997, when the hype around the plant arose, possibly after the Afrikaans 'Afrika-patat', since the tuber could possibly remind one of a patat or sweet potato. However, this is a most inappropriate name, since it is a corm (compressed underground stem, developing vertically) and not a tuber (swollen stem, like the potato, developing horizontally). Furthermore there is no reference in the scientific literature to this name.

The genus Hypoxis is large, with 76 species in Africa, 40 of which occur in South Africa. 16 species are endemic to SA.

Ecology
Hypoxis hemerocallidea is fire-tolerant, and occurs widely in grassland where fire is part of the ecological regime. It is dormant during the fire season and resprouts after fire. The fibres protect the corm against fire damage. Fire promotes the growth of new leaves. Seeds are also stimulated to germinate by fire.

The flowers are visited by bees and other pollinators. It is not known to be favoured as food by browsing herbivores.

Uses and cultural aspects
African potato (in the misapplied sense) has been used as a traditional medicine for centuries. It is a household name in South Africa and probably the best known muti plant in the country. The African potato has even been recommended by a former Minister of Health for inclusion in the daily diet of HIV patients.

Today it is an alleged component of numerous over-the-counter medicinal preparations. In a study on the plants sold at muti markets in the Eastern Cape, Hypoxis hemerocallidea was the most-traded plant.

The tuberous rootstock is traditionally used to treat a wide variety of ailments. Weak infusions and decoctions of the corm are used as a strengthening tonic and during convalescence, and against tuberculosis and cancer. It is also used for prostate hypertrophy, urinary tract infections, testicular tumors, as a laxative and to expel intestinal worms. Anxiety, palpitations, depression and rheumatoid arthritis are further ailments treated with the plant.

Hypoxis hemerocallidea is used to build up the immune system of patients suffering from cancer and HIV. A phytochemical derived from Hypoxis is hypoxoside. This is an inactive compound which is converted to rooperol, which has potent pharmacological properties relevant to cancer, inflammations and HIV. Extracts from H. hemerocallidea are also effective in the treatment of the urinary system.

Another compound isolated in Hypoxis is sitosterol or phytosterol, which is an immuno-enhancer. Sitosterols are found in many green plants, and this is the main component of the commercial product ‘Moducare'. However, the plant is no longer used to manufacture Moducare capsules. Pine oil and soya oil extracts are now used instead.

The plant and its derivatives are sold in many muti markets, and commercial products are widely available. However Hypoxis also contains toxic substances in the raw form, and has not been registered with the Medical Control Council for that reason. Warning: The raw products can be toxic and must be used with caution. It is recommended to use a shelf product as a safe alternative.

Other species in the genus are also toxic to humans (H. colchicifolia, H. villosa).

The leaves are used to make rope. The leaves and tuber are used as a dye and give a black colour, which is used to blacken floors.

Hypoxis hemerocallidea showing geometric triangular arrangement

Growing Hypoxis hemerocallidea 

The star flower is a very attractive, hardy garden plant. It is drought-tolerant, frost-resistant, very easy to grow and an asset to any garden. It grows well in full sun in well-drained soil.

Hypoxis hemerocallidea flowers freely throughout summer. The yellow star-like flowers are eye-catching in any setting. It is excellent for a rockery or as a border to flower beds, but is also suitable for container planting. When not in flower, the leaves are attractive and striking with their geometric triangular arrangement.

The bulbs are dormant in winter and need to be kept dry. The leaves die down after the summer, but appear in later winter, often before the summer rains.

The star flower is not easily propagated from seed, since the seeds remain dormant for about one year after flowering. During germination studies it was found that complete mechanical removal of the hard seed coat only led to partial germination. The dormancy would be the main reason why few seedlings are found in the field. Corm division is a more rapid and successful method of propagating the plants.

 

References and further reading

  • Albrecht, C.F.1966. Hypoxoside: a putative non toxic prodrug for the possible treatment of certain malignancies, HIV-infection and inflammatory conditions. In K. Hostettmann, F. Chinyanganya, M, Maillard & J.-L. Wolfender (eds), Chemistry, biological and pharmacological properties of African medicinal plants. Proceedings of the First International IOCD-Symposium Victoria Falls, Zimbabwe, Feb. 25–28. University of Zimbabwe Publications.
  • Dold, A.P. & M.L. Cocks. 2002. The trade in medicinal plants in the Eastern Cape Province, South Africa. South African Journal of Science 100: 425–430.
  • Drewes, S.E. & Kahn, F. 2004. The African potato (Hypoxis hemerocallidea): a chemical-historical perspective. South African Journal of Science 98: 589–597.
  • Germishuizen, G. & Meyer, N.L. (eds). 2003. Plants of southern Africa: an annotated checklist. Strelitzia 14. National Botanical Institute, Pretoria.
  • Hammerton, R.D., & J. Van Staden. 1988. Seed germination of Hypoxis hemerocallidea. South African Journal of Botany 54(3): 277–280.
  • Is this a cure or con? Sowetan. 21 May 1999.
  • Joffe, P. 2001. Creative gardening with indigenous plants. Briza Publications, Pretoria.
  • Klopper, R.R. et al. 2006. Checklist of the flowering plants of Sub-Saharan Africa. An index of accepted names and synonyms. Southern African Botanical Diversity Network Report No. 42. SABONET, Pretoria.
  • Louw. E. 1997. SA's Miracle Muthi. You magazine. 10 July 1997. 12–14.
  • Philips, E.P. 1925. Hypoxis rooperi. The Flowering Plants of South Africa 5: t. 172.
  • Pooley, E. 1998. A field guide to wild flowers of KwaZulu-Natal and the Eastern Region. Natal Flora Publications Trust, Durban.
  • Singh, Y. Hypoxis. Yellow stars of horticulture, folk remedies and conventional medicine. Veld & Flora. September 1999: 123–125.
  • Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
  • Van Wyk, B. & Malan, S. 1998. Field Guide to the Wild flowers of the Highveld. Struik.
  • Van Wyk, B-E. & Gericke, N. 2000. People's plants. A guide to useful plants of southern Africa. Briza Publications, Pretoria.
  • Van Wyk, B-E. et al. 1997. Medicinal plants of South Africa. Briza Publications, Pretoria.
  • Watt, J.M. & Breyer-Brandwijk, M.G. 1962. Medicinal and poisonous plants of southern and eastern Africa. Livingstone, Edinburgh and London.

 

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Reader's comment:

In October: 2012 Phillip Potgieter wrote to us to say:
Thank you for the very informative article on Hypoxis hemerocallidea. I noted that you list the most effective way of propagation of the star grass as via division, as these plants do not really form large clumps in a short time span I believe there is a better method. I live on a plot outside Pretoria close to Hartebeespoortdam and these plants are plentiful on the property. While cultivating a piece of earth a few years ago for the vegetable patch I accidently damaged one of these corms as it has not yet made leaves and I could not see the plant. It basically cut the bottom piece of the corm off just above the roots. To my surprise a few weeks later numerous little corms had formed on this bottom piece of the corm complete with little leaves and roots. I carefully removed and planted them in pots and have since replanted them in the garden and veld. Do try this as I got at least 10 plants from the one original corm. The piece of corm should be kept just below soil level and moist but not wet. I do not know whether this method of propagation works for other species of Hypoxis.

 


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