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Huernia keniensis R.E.Fr.

Protologue
Acta Horti Berg. 9: 79 (1927).
Family
Asclepiadaceae (APG: Apocynaceae)
Chromosome number
2n = 22, 44
Vernacular names
Kenyan dragon flower (En).
Origin and geographic distribution
Huernia keniensis occurs in Kenya and Tanzania.
Uses
In Kenya the sap from the stem is applied to wounds to dry them.
Huernia keniensis is grown as an ornamental in rock gardens and containers.
Botany
Small clump-forming shrub with succulent, 5-angular stems, up to 12 cm long and c. 1 cm in diameter, prostrate to erect, irregularly branching, grey-green with small brownish spots or reddish apex; tubercles small to large, acute; sap from stems clear. Leaves rudimentary or absent. Flowers 1–2 together, axillary, from the base or middle of the stems, bisexual, 5-merous, regular, drooping; pedicel c. 5 mm long; sepals triangular, c. 6 mm long; corolla 2–3(–5) cm in diameter, deeply campanulate or cup-shaped to globose, outside reddish to purplish, rarely cream-coloured, with pale venation, inside dark purple, densely papillose or sometimes glabrous, corolla lobes broadly triangular, with apex curved backwards, sometimes with 5 smaller lobes in the angle between the main lobes, more or less papillose on both sides, outer corona blackish purple, inner corona lobes fused into a disc. Fruit consists of a pair of follicles. Seeds with coma at apex.
Huernia comprises about 70 species; about 60 species occur in East and southern Africa, 1 species occurs in Nigeria, 6 in Yemen and 3 in Saudi Arabia. Many species can be grown as an ornamental in rock gardens or containers. Several intergeneric and intrageneric hybrids created in cultivation are known. Huernia differs from the morphologically very closely associated Duvalia by having glabrous stems without stipules.
In Huernia keniensis 5 varieties have been recognized, mainly based on differences in corolla size and shape. Flowers occur from June to October and do not have a carrion-like smell.
Other Huernia species with medicinal uses are known in East and southern Africa. The crushed leaves of Huernia concinna N.E.Br. from Ethiopia and Somalia are used in Ethiopia as a dressing to reduce swellings. Huernia hystrix (Hook.f.) N.E.Br. occurs in Zimbabwe, Mozambique, South Africa and Swaziland. In Swaziland a stem infusion is taken as a sexual stimulant. It is drought-tolerant and can be grown in rock gardens. Stem and root extract showed anti-inflammatory activity in vitro. It has become rare in South Africa due to overharvesting and in-vitro propagation techniques have been developed.
Ecology
Huernia keniensis occurs in stony to rocky localities, usually in bright shade, at 1500–2000 m altitude.
Management
Huernia keniensis, like other Huernia spp., is easy to propagate by stem cuttings. It is self-sterile and flowers from different clones are needed to produce viable seeds.
The plant should be kept relatively dry in the cold season at temperatures not lower than 10°C. It prefers a gritty, fast draining soil, which needs to get quite dry before watering. Huernia keniensis should not be exposed to direct sun that make them turn brown, and stops growth. It is sensitive to mealy bugs.
Genetic resources and breeding
It is not known whether Huernia keniensis is common in its natural environment, but it is morphologically variable and quite commonly cultivated as an ornamental. Therefore, it seems unlikely to be threatened by genetic erosion.
Prospects
Huernia keniensis will remain of limited importance as a medicinal plant. However, as an ornamental it is of interest to plant collectors.
Major references
• Albers, F. & Meve, U. (Editors), 2002. Illustrated handbook of succulent plants. Asclepiadaceae. Springer, Berlin, Heidelberg, Germany. 318 pp.
• Kokwaro, J.O., 1993. Medicinal plants of East Africa. 2nd Edition. Kenya Literature Bureau, Nairobi, Kenya. 401 pp.
• Leach, L.C., 1988. A revision of Huernia R.Br. (Asclepiadaceae). Excelsa 4: 1–197.
Other references
• Amoo, S.O., Finnie, J.F. & Van Staden, J., 2009. In vitro propagation of Huernia hystrix: an endangered medicinal and ornamental succulent. Plant Cell, Tissue and Organ Culture 96: 273–278.
• Ndawonde, B.G., Zobolo, A.M., Dlamini, E.T. & Siebert, S.J., 2007. A survey of plants sold by traders at Zululand muthi markets, with a view to selecting popular plant species for propagation in communal gardens. African Journal of Range and Forage Science 24(2): 103–107.
• Teklehaymanot, T. & Giday, M., 2007. Ethnobotanical study of medicinal plants used by people in Zegie Peninsula, Northwestern Ethiopia. Journal of Ethnobiology and Ethnomedicine 3: 12.
Author(s)
G.H. Schmelzer
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
G.H. Schmelzer
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
A. Gurib-Fakim
Faculty of Science, University of Mauritius, Réduit, Mauritius
Associate editors
R. Arroo
Leicester School of Pharmacy, Natural Products Research, De Montfort University, The Gateway, Leicester LE1 9BH, United Kingdom
Photo editor
G.H. Schmelzer
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Schmelzer, G.H., 2010. Huernia keniensis R.E.Fr. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(2): Medicinal plants/Plantes médicinales 2. [CD-Rom]. PROTA, Wageningen, Netherlands.

obtained from Asclepidarium




obtained from Stapeliads




obtained from Asclepidarium




obtained from The Asclepiad Exhibition




obtained from The Asclepiad Exhibition