Shami Tree is worshipped in Hinduism and it is believed that Agni, the god of fire, stayed in the tree after the curse by Sage Bhrigu. The sacredness of Shami Tree is due to Agni hiding in the tree.
Legend has is that Agni was cursed by Sage Bhrigu for providing wrong information regarding his marriage with Puloma.
Agni then hid underground to escape from the curse.
During this period, Devas lost heaven to demons. Only a son born from Shiva could defeat the demons. For this Devas need the help of Agni.
But they could not locate Agni has he was missing. Finally Devas found Agni hiding in the Shami Tree. He helped Devas in the birth of Lord Kartikeya.