What is a Cactus?

What is a Cactus?

All cacti belong to the plant family Cactaceae. They store large quantities of water in their leaves, stems or roots, giving them a fleshy character. Cacti grow in drought-prone, nearly arid climates or physiologically dry soil.

The spines (thorns) can absorb moisture in the air to some extent. It hardly loses the absorbed water. The spines perform another important function. They trap moisture and create a moisture layer near the surface of the cactus stem. This helps the plant to reduce transpiration and thus conserve some water. Spines can also protect the plant from herbivores.

Most of the time cacti have a waxy layer on the stems, and possess a very thick cuticle, which is impervious to water. When considering the body shape of the cactus plant it is cylindrical.