Euphorbia cooperi is a succulent tree up to 7 m tall, with conspicuous candelabra-like branches. This plant has milky latex highly poisonous to humans and animals. This spiny, succulent tree has a grey naked trunk up to 3 m high. Round holes on the trunk indicate where old branches have fallen off. Branches (succulent leaves) are conspicuously 4- to 6-winged and resemble a chunky string of beads. The triangular segments are 50-150 x 120 mm. The spines form a spiky margin along each ridge on the branches. Spines are found in pairs and are usually 5 to 7 mm long.