Cacti have a thick, hard-walled, succulent stem – when it rains, water is stored in the stem. ... The inside of the stem is either spongy or hollow (depending on the cactus). A thick, waxy coating keeps the water inside the cactus from evaporating.

How does a cactus store water?

Primarily, cactuses store water in collapsible-water storage cells found in the stem. However, some cactuses also store water in their roots that are modified to perform this function. The collapsible water-storage cells appear as holes or spaces in the stem and retain water for a fairly long time.

Can cactuses store water?

The spines on a cactus help to protect it from humans and animals. Its roots are spread out to collect water when it does rain and it stores water in its body for future use.