Euphorbia sekukuniensis R.A.Dyer
Common names: Sekhukhune candelabra-tree, Sekhukhune euphorbia (Eng.); sekhukhunenaboom (Afr.)
SA Tree No: 353
A rare, small, succulent tree that is endemic in Sekhukhuneland, in Mpumalanga and Limpopo, where it occurs in a specialized habitat.
Euphorbia sekukuniensis is a small, spiny, succulent tree that grows up to 7 m tall, with a single main stem marked with 7 to 10 vertical lines and scars from old spines.
It has a candelabra-like crown of branchlets that spreads up to 2.0 to 2.5 m.
The branchlets are about 1 m long, slender, up to 20 mm in diameter, 4-angled, constricted at intervals of 200 mm and re-branched above the constrictions. Spines are in pairs, 5 to 8 mm long, and stout spine shields unite to form a horny margin. It has an inflorescence that is a cyme. Flowers form a yellowish green, cuplike structure on a short pedicel, in late winter to early spring (August). The fruit is a 3-lobed capsule, 8–9 mm in diameter.
Euphorbia sekukuniensis is closely related to E. grandidens, E. evansii and E. tetragona, but can be differentiated by the deeply 3-angled capsules and united spines that form a margin on the branches.
Euphorbia sekukuniensis is assessed as Rare in the Red List of South African plants. It has a restricted distribution and occurs as small, isolated populations scattered over a wide area because of its specialized habitat on shallow norite soils. Mining is a potential threat to this species.
Distribution and habitat
Euphorbia sekukuniensis is endemic in South Africa, only known in the Limpopo and Mpumalanga Provinces. It occurs in the Lydenburg District, Sekhukhuneland, the Steelpoort River Valley and to the Olifants River.
The Sekhukhune euphorbia occurs in the Savanna Biome, Central Bushveld Bioregion and Grassland Biome, Mesic Highveld Grassland Bioregion. The vegetation types where this species is found, is Lydenburg Montane Grassland, Sekhukhune Montane Grassland, Sekhukhune Mountain Bushveld and Ohrigstad Mountain Bushveld. It is found in closed woodland and thicket, in shallow norite soils, on rocky outcrops, among large boulders, 900–1 300 m altitude.The summers are hot with cold dry winters, with an average daily minimum temperature of 2.8ºC in winter and average maximum of 24.9ºC in summer. Rainfall occurs mainly in summer and ranges between 500–700 mm. There are a number of other associated species that occur in the same habitat, such as Blepharis subvolubilis, Olea capensis subsp. enervis, Searsia batophylla, S. wilmsii and S. sekhukhuniensis, Dioscorea dregeana, Aloe fosteri, Grewia vernicosa and G. flavescens, Vachellia nilotica subsp. kraussiana, Barleria senensis, Euphorbia barnardii and Rhoicissus sekhukhuniensis.
Derivation of name and historical aspects
The genus Euphorbia was named after Euphorbus, who was a medical doctor to King Juba of Mauritania, in the first century. The name Euphorbia is from a Greek word, euphorbe, that means ‘good pasture’, eu means ‘well’ and phorbe means ‘pasture’ The specific epithet sekukuneniensis refers to Sekhukhuneland where this species naturally occurs. This name originates from King Sekhukhune who was a king in the1870s in the region that is now known as Sekhukhuneland.
Euphorbia sekukuniensis was first collected in 1930 by P. Ross-Frames and in 1940, it was described by R.A Dyer from plant material that was collected by W.G. Barnard and Dr F.Z. van der Merwe.
The family Euphorbiaceae has over 200 genera, such as Croton, Dalechampia, Erythrococca, Clutia, Acalypha, to name a few and over 6 000 species. Euphorbia is found in all continents and countries, except Antartica. In South Africa we have 32 genera and about approximately 188 known species.
Flowers of Euphorbia sekukuniensis attract butterflies, bees and other insects Fertilized flowers form capsules. When the fruits are ripe, the capsules dry, and split open to release the seeds. Seeds are dispersed by wind in late summer to autumn and are banked in the soil during the dry winter season. The seeds germinate during the summer rainfall season. This species has succulent stems and branchlets to store the water for the dry winter season and its shallow root system makes it more adaptable for growing in rocky areas and shallow soil.
Euphorbia sekukuniensis is a commonly used ornamental plant in landscaping. Although many euphorbias are known to be used, such as E. decussata, which is traditionally used as yeast, E. ingens, which is used for building material, and E. virosa, E. subsala and E. cooperi, which are used for hunting and fishing, there are no records of Euphorbia sekukuniensis being used for medicinal or cultural purposes.
Growing Euphorbia sekukuniensis
Euphorbia sekukuniensis grows slowly and thrives in hot climates and is also resistant to light frost. Plants can easily be propagated sexually (by seeds) and asexually (by cuttings). Coarse river sand is an ideal medium for sowing the seeds and rooting cuttings.
Propagation from seeds is done in autumn (from February to April) and cuttings are taken in late summer and in spring. Keep in a warm, moist area. When propagating from cuttings it is important to leave the cuttings for about 3 to 4 days for the milky latex to dry, before putting the cuttings into the medium. Keep the soil moist, not wet to avoid rotting. Use coarse bark at the bottom of the seedling tray or pot to improve water drainage.
This species grows very well in full-sun positions, in rocky areas such as rock gardens. Water the plants in summer and keep them dry in winter. Other Euphorbia species that best complement E. sekukuniensis include, E. ingens, E. cooperi, E. triangularis, E. grandicornis, E. tetragona and E. grandidens, and small succulent plants such as species of Aloe, Crassula, Cotyledon, Tylecodon, Cyphostemma, Gasteria, Cheriodopsis, Kalanchoe, Cyphostemma, Adromischus, etc.
- Coates Palgrave, K. 1983. Trees of southern Africa. Struik, Cape Town.
- Muchina, L. & Rutherford, M.C. (eds). 2006. The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria.
- Van Wyk, B.E. & Gericke, N. 2000. People's plants. Briza Publications, Pretoria.
- White, A., Dyer, R.A. & Sloane, B.L. 1941. The succulent Euphorbieae (southern Africa). Volume 1 & 2. Abbey Garden Press, California.
- Winter, P.J.D., Victor, J.E. & Von Staden, L. 2008. Euphorbia sekukuniensis R.A.Dyer. National Assessment: Red List of South African plants version 2017.1. Accessed on 2017/05/11.
Pretoria National Botanical Garden
Plant Type: Tree
SA Distribution: Limpopo, Mpumalanga
Soil type: Clay
Flowering season: Spring
Flower colour: Yellow
Aspect: Full Sun
Gardening skill: Easy