Water Storage: Up to 90% of a cactus’s mass can be water. Their thick, often ribbed stems act as reservoirs, expanding to soak up large amounts of water during rare rainfall and contracting as they use it during droughts.

Areoles: These are small, fuzzy bumps unique to cacti from which spines, flowers, and branches grow. They are the primary feature that distinguishes cacti from other succulents.

Spines (Modified Leaves): Instead of standard leaves, most cacti have spines that serve triple duty: they protect the plant from herbivores, provide shade to lower stem temperature, and help condense moisture from the air to drip down to the roots.

Nighttime Breathing (CAM Photosynthesis): To prevent water loss, cacti open their pores (stomata) only at night to take in carbon dioxide, which they store to use for photosynthesis during the day while keeping pores closed against the hot sun.

Shallow Root Systems: Most cacti have wide, shallow roots that spread like a net near the surface to quickly absorb even light showers or morning dew.