INTRODUCTION What follows is the collection of PowerPoint slides that illustrated Gus Le Breton's talk to…
Euphorbia is the largest and most complex genera of flowering plants containing some 2000 species. Botanists have tried unsuccessfully to subdivide the genus into several smaller genera.
Euphorbias range from tiny annual plants to large and long-lived trees. They are “succulents” i.e. plants that store water in thickened stems or leaves in order to better cope with arid conditions. All have a milky, white, latex sap. Some euphorbias are very familiar, such as Poinsettia, associated in North America and Europe with Christmas.
Euphorbias from the deserts of southern Africa and Madagascar appear similar to the cacti (which are also succulents) of North and South America, so they are often incorrectly referred to as cacti.
Some differences are:
- Cacti do not secrete a sticky, milky white fluid, which has evolved in euphorbia to discourage herbivores;
- Many cacti have very showy flowers, often opening at night to attract pollinators in the cool hours. Euphorbia flowers are tiny;
- Individual flowers are either male or female. These flowers have no petals or other parts that are typical of flowers in other kinds of plants. Parts of the flower have evolved to attract pollinators with nectar, and with shapes and colours that function like petals and other plant parts.
- Euphorbia has been extensively hybridized for garden use around the world, and also is used for a range of medical treatments. Care must be taken especially with the latex, which can produce extremely painful inflammation especially around the eyes
- Euphorbias from desert habitats have thorns, usually in pairs, which are modified stems, while cacti have spines. Spines, which are modified leaves, come from areoles (fuzzy dots from which spines, stems and flowers grow), which are structures that all cacti have. Euphorbias do not have areoles.
contributed by Robin Wild
Click below to read about the Convergent Evolution of Cacti and Euphorbias
Scientific name: Euphorbia ingens
English name: Candelabra Tree
Afrikaans name: Naboom (meaning “almost tree”)
Shona names: Mugonde, Muhonde, Mukonde
Ndebele name: Umhlonho
Euphorbia ingens is a massive tree-size succulent up to 10 metres tall.
The ridges of the branches are set with short thorns. (See picture above)
The flowering parts are set at the top of the vertical branches and the flowers are small and yellow.
The flowers give rise to fruit about the size of a small plum.