Cacti are succulent plants. This means that they have thick tissues that take up and hold large amounts of water. The stored water keeps them alive during dry periods. Unlike many plants, cacti do not have deep roots. Instead, they have roots that spread out near the surface of the soil. This is important to their survival. These roots absorb water from a wide area when it rains.

There are about 1,650 species, or types, of cacti. These plants grow mainly in the dry areas of the United States, Mexico, Central America, and South America. Mexico has the most significant number and variety of cacti.

Cactuses, or cacti, are desert plants. They grow in dry places where other plants have trouble living. Their ability to store water keeps them alive. Sharp spines, or needles also protect cacti.