How does a cactus live with little water?

A cactus plant needs water just like any other plant. They have several methods for conserving the little water they get from the occasional rains.

1. They have roots which spread out near the surface to quickly catch as much water as possible before it drains away or evaporates. Large, column-like cacti also have a long taproot which goes down deep, primarily for support, but also to access groundwater and minerals.

2. They have thick, waterproof exteriors to preserve internal moisture.

3. They have spines, which not only protect the cactus from animals, but also shade part of the plant to reduce the small amount of remaining evaporation.

Cactus are so well adapted to dry conditions they will rot and die if they remain moist too long. They must be dry most of the time, especially their roots. That is why they grow in sandy, well drained soil that dries quickly after a rain.