Book 16, Question 71
Why Do Big Cacti Have Pleated Sides?
Big cacti have pleated sides because the pleats work like an accordion! They let the cactus swell up when it drinks and shrink when the water is used. The pleats are called ribs, and they can fold and unfold again and again.
More fun facts
- The saguaro is the largest cactus in the United States.
- The pleats on the outside match the number of woody ribs inside.
- When the desert is dry, the saguaro uses its stored water and its pleats shrink.
- As a saguaro grows, its ribs sometimes fork, and the pleat outside forks in the same place.
- Saguaros grow arms as they age, and they rarely grow perfectly even.
Sources: National Park Service, National Park Service
Questions kids ask
What happens to a saguaro's pleats when it is dry?
The saguaro uses its stored water and its pleats shrink.