A cactus is a succulent that has spongy roots and leaves because of that they can hold the water they get and save it for later. They have to be able to do this because most cacti live in hot, dry areas that don’t get much rain. The tap root of a cactus is longer and stronger than the tap root of most plants. The tap root soaks up the water and holds on to it; sending little drinks at a time to the rest of the plant. A cactus also has number of small roots that run close to the surface of the ground. This lets the roots soak up any rain that falls quickly.