What is the prepositional phrase in this sentence tree swayed gently wind?

The prepositional phrase in the sentence "The tree swayed gently in the wind" is "in the wind".

Here's why:

* Preposition: The word "in" is a preposition.

* Object of the Preposition: The phrase "the wind" is the object of the preposition "in".

* Function: The entire phrase "in the wind" acts as an adverbial phrase, modifying the verb "swayed" by telling us where the tree swayed.