Euphorbia clivicola This is a critically endangered, low-growing succulent perennial endemic to the Limpopo Province. It has short, spiny, 4-angled branches arising from an underground system of rhizomes and roots. It can be propagated by means of shoots or seed.
Euphorbia clivicola is a short, spiny perennial succulent with a subterranean root system and a root tuber which is about 150 mm long and 20-30 mm thick and tapers towards the base.
The flowers are very small and unisexual and are arranged in cup-like structures with yellow, nectar-bearing glands around the rim. These structures are called cyathia (singular: cyathium). They are arranged in groups of three at flowering eyes towards the end of the branches. In each group of three cyathia the central one contains only male flowers and the outer two contain both male and female flowers. Seeds are produced from mid-May to mid-July in a three-chambered fruit capsule with 1 ovule in each locule. Plants produce toxic, milky latex (Smart 1999).
Euphorbia clivicola is listed on the Red List of South African Plants as Critically Endangered (CR) (Pfab et al. 2008).
Population size: The numbers of E. clivicola plants have decreased drastically in the past two decades. In 1986 there were 1,500 individuals in the Percy Fyfe Nature Reserve and 3,000 individuals in the urban area (Fourie 1986). In 1996, the numbers decreased to 165 and 382 in the respective areas (Hilton-Taylor 1996). In 2005, there were 58 plants left in the nature reserve while the plants in the urban area had increased to 651 (D. Engelbrecht, pers. comm.). Last year a survey was done and only ten plants were found in the nature reserve (E.T. Moeng, pers. comm.).
Threats: The plants in the Percy Fyfe Nature Reserve are decreasing due to continuous trampling by antelopes, herbivory by insects such as Protostrophus beetle and poor fire management (Pfab & Witkowski 1998).
The plants in Polokwane occur on the fringes of a growing human settlement. The dumping of building rubble on the plants has lead to a number of losses. Recreational activities such as quad biking also led to the disruption of the growth habit and death of some plants. Illegal waste dumping in the area has resulted in the introduction of rodents that feed on the branches and fruits of the plant (D. Engelbrecht, pers. comm.).
Distribution and habitat
Euphorbia clivicola occurs in two populations which are about 38 km apart. The one population is situated in the Percy Fyfe Nature Reserve southwest of Polokwane while the other population occurs in an urban area on the outskirts of Polokwane (Pfab & Witkowski 1998). Euphorbia clivicola grows on gentle slopes with northern and north-eastern aspects. The veld type around the plants is classified as sour bushveld derived from white quartzite stones (Dyer 1951).