The San Pedro Cactus (Echinopsis pachanoi) is a tall, columnar cactus native to the Andes Mountains in South America. It can grow up to 20 feet tall and is characterized by its green, ribbed stems. This cactus thrives in dry, sunny environments and is often found in Peru, Ecuador, and Bolivia. Traditionally, the San Pedro Cactus has been used in indigenous cultures for its psychoactive properties, primarily due to the presence of the compound mescaline. It is commonly used in spiritual ceremonies and healing practices. In recent years, it has gained popularity in alternative medicine and among those interested in entheogenic substances.