Cacti are plants that have various shapes and sizes. The term cactus comes from the Greek word kaktos, meaning thorny plant. Cacti grew about 100 million years ago, with tall shapes. After the volcanic event on the American continent, cacti reappeared. It's just that now cacti grow in small shapes, as a result of evolution. To date, around 2,000 species of cactus have spread throughout the world. Cacti originate from barren plains such as Mexico and South America.