South Africa is rich in a variety of succulents totalling half of the succulents found worldwide. Aloes are probably most commonly known, but Euphorbias are fascinating in their own right.
SUCCULENTS FORM A VERY important part of our flora. Due to the extreme variation in habitat as a result of variable climatic conditions, topography, soil types and large and extensive arid areas, South Africa is rich in succulent plants. There are more than 4 600 species, which make up almost 20% of the recorded plant species in South Africa and represent nearly 50% of the total number of succulent plants worldwide. Succulents have developed special mechanisms for the storage of moisture to ensure their survival in arid areas and through dry seasons. Euphorbias are stem succulents with the stem in most cases being the moisture storage organ. Most have only rudimentary leaves or thorns and the stem largely takes over the photosynthetic process.
The Euphorbia genus is one of a large number of genera belonging to the worldwide family Euphorbiaceae, characterised by a milky latex and small specialised flowers. The latex is often poisonous and can sometimes cause severe skin irritation. Euphorbias are a very large and variable group of plants ranging from widespread dwarf to medium-size succulents with bizarre shapes to spiny giants in the thicket and savannah vegetation of the eastern regions. Nearly 300 species of Euphorbia have been recorded in South Africa (Plants of Southern Africa: An Annotated Checklist, published by the National Botanical Institute, 2003). The name of the genus originated in Roman times when King Juba ll of Mauritania, who married the daughter of Antony and Cleopatra, named a medicinal plant from the Atlas mountains after his physician Euphorbus (now probably Euphorbia resinifera).
The medicinal properties of the milky and sticky latex, which is tapped and dried when it coagulates into a gum, was well-known even then, being described as an excellent remedy for the “stings of serpents”. It is recorded that caution had to be exercised when harvesting the latex because of the irritation it caused when it was handled. The latex of Euphorbias was known and used by the San people as arrow poison. When rubber was scarce after World War ll, it was attempted in the Eastern Cape to tap the latex to manufacture rubber. While small amounts of rubber can certainly be produced from Euphorbia latex, the commercial propagation of these plants was unsuccessful and the inhospitable terrain where they occur resulted in the demise of the enterprise.
This information comes from a fascinating account of the classical origins of the name and a summary of the family Euphorbiaceae by Estelle Brink, which was published in December 1992 in The Phoenix by the Albany Museum in Grahamstown. Probably the best-known Euphorbia is Euphorbia ingens, the naboom, after which Naboomspruit was named and where it is very common. While not the tallest, it is the largest Euphorbia. It does not shed its branches, but rebranches each year forming a dense dark green crown. The naboom is widespread throughout the northern provinces, Zimbabwe and Mozambique. Another well-known Euphorbia in the Eastern Cape is the Sweet Noors (Euphorbia coerulescens) after which the Noorsveld is named. Noorsveld is restricted to a small area of the arid interior of the Eastern Cape, south of Graaff Reinet, dominated by dense stands of this erect spiny plant averaging about a metre in height. Sweet Noors is so named because it is palatable and is used as valuable drought fodder for sheep and Angora goats.
The cushion Euphorbias are another well-known group. These form dense mats, sometimes metres in diameter, in various parts of the eastern region. Euphorbia pulvinata is confined to the southern and more arid parts of the Karoo and extends into the grasslands of the Eastern Cape. While inviting as a cushion from a distance, beware of sitting or tramping on it – the thorns can inflict severe injuries. I have noticed, however, that in times of feed scarcity, sheep and goats are not averse to eating this plant. A more benign cushion Euphorbia is Euphorbia clavarioides, which does not have thorns and occurs in the highland areas of the Eastern Cape, extending into Lesotho and the Drakensberg. There are various types of low-growing dwarf Euphorbias collectively known as “vingerpolle”, which occur throughout the country and are fairly common in grasslands. These are attractive plants that make good rockery subjects, such as the aptly named Medusa’s Head, Euphorbia caput-medusae.
The most well-known and popular Euphorbias among collectors are the sub-globose Euphorbias. These are dwarf Euphorbias hemispherical in shape and often with attractive markings. They are popular because they are attractive and make fascinating pot plants. Confined to a few specialised habitats in the Eastern Cape, the wild populations have suffered extensive poaching and are regarded as highly vulnerable. The rare Euphorbia obesa from the Graaff Reinet area is very restricted, but hopefully has a small measure of protection from the landowners on whose properties they occur. Euphorbia meloformis is a similar species with a ribbed hemispherical shape. According to Gerhard Marx, (The Phoenix magazine of the Albany Museum, December 1998), the population in the Motherwell and Coega region near Port Elizabeth is doomed to extinction because of industrial expansion in this area. However, there are larger populations north of Grahamstown, extending to the Alice and Peddie areas where some larger plants occur. Euphorbia valida is a slightly larger and taller member of this group, occurring along the Fish River in the Carlisle Bridge area and extending from Steytlerville right through the southern Somerset East and Bedford districts.
The best-known locality of Euphorbia valida is on the Dikkop Flats where a reserve has been created to protect it. It remains a sobering thought that entire natural populations of these rare and localised species are in the hands of a few farmers upon whom their survival depends. Cameron McMaster ([email protected])
