Spurges resemble cacti but are easily distinguished by there white or yellow sap (translucent in cacti) and there paired spines (in cacti, in clusters of several spines). The spines of spurges have evolved from the stipules, while the spines of cacti have evolved from the leaves. 

Like many other spurges, the Canary Island spurge uses CAM photosynthesis, an adaptation to drought. In CAM photosynthesis, the plant keeps its stomata closed during the day to prevent evaporation. Instead, the stomata open at night, when the plant stores carbon dioxide in the cell vacuole. During the day, the plant releases the stored carbon dioxide to be used in photosynthesis. 

The sap of the spurge is toxic. It irritates the skin and can cause severe pain to mucous membranes and even blindness if it gets into the eyes. According to some reports, the milky sap of the spurges was used as a “bioweapon” in ancient times by spraying it on cavalry troops. Many spurges, such as this Canary Island spurge, are used as ornamental or houseplants, so you have to be careful when caring for spurges!