80s movie ID, fantasy or sci fi with mute girl?

Ok I think it was a fantasy movie, but it could have been a light on the science scifi movie.

The characters have discovered a new area or planet, and they go out an explore and one of them is a mute young woman who has a scene of her standing under a tree or something shedding white flowers or leaves that she plays in.

Later in the movie she is the first one to realize there is something off about the place, but can’t communicate it.

Reminded me very much of the River Tam character in Firefly.

I was going to say Firefly but you already thought of that. You know there was a movie too, right. Serenity.

Yea, can’t be that as I saw this on TV as a kid a decade or two before Serenity got made.