Euphorbias contain a toxin that is known to be carcinogenic. The milky sap can cause inflammation of the skin and mucous membranes of the eyes, nose and mouth. The chemical resinferatoxin has an irritating effect which is stronger than capsaicin, the substance that makes chillies hot. So never feed to tortoises and wear protective clothing when handling this plant.
Some of the commoner cultivated Euphorbias are:
E. robbiae, E. characias, E. griffithii, E. myrsinites, E. cyparissias, E. atropurpurea
Although most garden Euphorbia are hardy in the UK, the Euphorbia atropurpurea is not frost hardy.