👉 Megacalanus is a type of plant in the family Lamiaceae, commonly known as the "giant" or "world's largest" cacti. These plants are characterized by their large size and can grow up to 30 feet (9 meters) tall, with a trunk diameter of over 15 inches (40 cm), making them some of the largest cacti in the world. They are often used as ornamental plants for homes or gardens due