This tree is also known as Shami tree and is very sacred to Hindus. This tree comes into prominence during Dasara festival. The botanical name of this tree is Prosopis spicigera. Every Hindu warrior before going for war would offer prayers to Banni tree and then proceed. They believed that they would emerge victorious in the war. The legend behind is rooted in the great epic Mahabharatha. When Pandavas were in exile for 14 years, they had to spend one-year incognito. During this period they had to hide their precious weapons lest they give away their identity. They chose the Shami tree to hide their weapons. After a year, they came back to the tree and found their weapons intact. They worshiped the tree and asked for power and victory in the ensuing battle between the Pandavas and Kauravas. Pandavas won the battle and hence it is believed that the Banni tree gives power and victory to those who pray to it.
Thus on Vijayadashami day people exchange the Banni/Shami leaves and greet and wish each other. This custom is followed in North Karnataka and Maharashtra.
In Mysore, the Dasara procession would reach Bannimantap, and the Maharaja would perform pooja/prayer to Banni tree and carry a branch of this tree back to his palace.