Onstage, you notice the silhouettes of...human faces in the branches? This could either be an instance of pareidolia (a normal and perfectly healthy neuro-perceptual phenomenon) or could it be...

Dryads! Also known as nymphs or tree spirits. These were minor Greek goddesses, usually tied to a specific place.

Hamadryad is the Greek specification for Dryads who live in trees. Hamadryads are born bonded to a certain tree and are the tree itself, whereas a normal dryad is simply the indwelling entity, or spirit, of the tree. Nonetheless, these spirits are fused with the trees themselves and have the capability to take humanoid form, if you're lucky enough to meet one.

Dryads are believed to have beneficial, supernatural powers of nature; they bring a sense of awe and wonder to mortals, but also terror and fear at times. They are not to be taken lightly but deserve the respect granted to any divine being.

LINK Article Mythology Source "Dryads, Greek Nyphs"