Cacti are unique plants that thrive in dry, desert environments. They are known for their thick, fleshy stems that store water, allowing them to survive long periods without rain. Most cacti have spines instead of leaves, which help reduce water loss and protect them from animals that might want to eat them. These fascinating plants come in many shapes and sizes, from small, round varieties to tall, tree-like forms. Some popular types of cacti include the saguaro, which can grow to be quite large, and the barrel cactus, known for its rounded shape. Cacti are not only beautiful but also play an important role in their ecosystems.