bo tree or pipal (pēˈpəl) [key], fig tree ( Ficus religiosa ) of India held sacred by the Buddhists, who believe that Gautama received enlightenment under a bo tree at Bodh Gaya. A slip of this tree was planted at Anuradhapura to become one of the oldest known trees. The bo tree attains great size and age; the leaves, which hang from long, flexible petioles, rustle in the slightest breeze. Pipal is also spelled peepul or pipul. The bo tree is classified in the division Magnoliophyta, class Magnoliopsida, order Urticales, family Moraceae.