The Green Planet

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Narrator

No matter how old a desert plant is, water is always precious, whether gathered from melting snow... (thunder rumbling) Or a shower of rain. (upbeat dramatic music) (storm brewing) (rain pelting) (upbeat dramatic music) So cacti have developed extraordinary adaptations that enable them to not only collect water, but to retain it. (upbeat dramatic music) Instead of leaves, which would lose precious moisture through evaporation, they have spines. Each spine has a tiny pad at its base where the water is absorbed. And then stored in the great swollen trunk. A large Saguaro can hold over 1,000 gallons of water, and is able to do so because it has another special adaptation. (cactus stretching) The ridges on its surface are like the pleats on an accordion. They allow the Saguaro to change its shape. After rain has fallen, the pleats expands and the Saguaro fills up its water tank. (upbeat dramatic music) In the dry times, it uses its water to grow, produce flowers and, eventually, seeds. (birds singing) Fully loaded with water, this Saguaro won't need to drink a single drop for another year.