Euphorbia ferox is one of the small euphorbias of the Karoo that grow thick columns or stems from a central branching base. Eventually the mature plant is a clump of erect stems armed by vertical rows of hefty spines or thorns along the vertical ridges of each stem. While young on new growth the spines are red or purple, the old ones are pale grey lower down.
E. ferox produces yellow flowers in spring. It is a popular garden plant having found its way to many parts of the world. The plant copes with drought and temperature extremes, although some summer watering and semi-shade make it look better.