Euphorbia heptagona grows in the Eastern and Western Cape on rocky Karoo-like slopes. In Afrikaans it has the common names of donkienoorsdoring and klipnoors. It branches much and reaches a height of 1 m. The species is dioecious; male and female flowers occurring on separate plants. The grey-green stems have six to ten ridges, the name heptagona suggesting a modus of seven. The long spines on the ridges are light brown or yellow to reddish brown when they are young on the stem tops.
This specimen was photographed at Kirstenbosch. It was marked as Euphorbia heptagona var. heptagona. There are also four other variations: var. dentata, probably more confined to the Eastern Cape, as well as var. ramosa, var. subsessilis and var. viridis. Details regarding the differences among the variations could not be accessed in the freely available literature. Flowering occurs from June to September. The cyathia are green, yellow-green or reddish. The plant population is currently stable, but sales are controlled to protect the species (Vlok and Schutte Vlok, 2010; Bond and Goldblatt, 1984; Wikipedia).