In some regions, Hindus perform ritualistic marriage of peepal tree and neem tree. This form of worship is associated with fertility and there is a symbolism associated with it. It is a kind of prayer and ritual to the almighty.
Peepal tree is considered as male principle (ashwatta narayana) having multiple seeds for maximum propagation. The neem tree is always associated with Mother Goddess Shakti or female principle. This is because it has a single large egg like seed.
The ritual and prayer thus unites male principle with female principle. Thus it is a fertility rite performed for healthy children.