Euphorbia atrispina is a spiny succulent with small yellow flowers that bloom at the tips of new spines on the stem top in Spring. Young plants may look like little trees or spreading shrubs. The mature plant has a mounded cushion shape with a large number of stem tips visible on the dome-like surface. The fruits are spherical and purple. A milky substance will ooze out if the plant is injured in any way and is harmful to skin and should not come in contact with one's eyes. The plant grows in the Little Karoo between Ladismith and Oudtshoorn, as well as on rocky slopes towards the coast.