Though banana is not a tree but it is considered a tree because of its structure and size. It is a very sacred tree and all parts of the tree are used for some purpose or the other. For example, the trunk of banana is used to erect welcoming gates. The leaves are used to make the ceremonial pavilion. In some pooja, the leaves are used to serve "prashad".
Just as leaves of bel tree are customarily offered to Lord Siva, it is believed that offering of the leaves of banana pleases Lord Ganesa. Banana as a fruit is offered to Lord Vishnu and Laksmi. In fact, the eleventh day of the bright half of Pausa (December-January) is considered to be very auspicious to offer banana to Lord Vishnu and Goddess Laxmi and sixth day of the bright fortnight of Kartika (October-November) is considered auspicious to offer banana to the Sun god.
In some regions, banana tree is worshipped while performing Kadali Vrata or fast. According to tradition, during Vaisakha, Magha or Kartika sukla caturdasi, a banana tree is planted and nurtured till it bears fruit. It is said that worshiping the tree with flowers, fruit, etc. will help in the welfare of one's family.