A cactus is a type of plant specially adapted to survive in hot, dry places where most other plants would wither and die. Instead of broad, thin leaves that lose water quickly, cacti have thick, waxy skin that holds moisture inside like a natural water bottle. Many cacti are covered in sharp spines that protect them from thirsty animals looking for a drink.

Cacti come in remarkable shapes and sizes. The towering saguaro cactus of Arizona can grow fifty feet tall with arms that reach toward the sky, living for over 150 years. The small, round barrel cactus stores water in its thick stem. Some cacti bloom with stunning flowers in brilliant reds, yellows, and pinks.

These plants grow naturally in the Americas, from Canadian deserts to South American mountains. Their ability to thrive where water is scarce makes them symbols of toughness and adaptation. When someone calls you a cactus, though, they probably mean you're acting a bit prickly!