Cacti are usually found in deserts. Cactus spines are modified leaves. They protect the plant from predators. These spines also provide shade to the surface of the cacti by protecting them from the harsh sun. The shade created by the spines also helps to lower the temperature of the surface of cacti, which reduces the amount of water lost through the cactus to the atmosphere. Spines also help some kinds of cacti to take the roots into the soil and spread. Some spines, like that of ‘cholla’ that is a shrubby cactus found in North American deserts, detach and cling to animals or people who come close to them. Prickly pear cactus is used as fodder and food. Certain varieties of Cacti are used as decorative plants.