The tree has only just started to cover her face, however her mouth is seconds away from being covered by a porous, spongy layer that she will still be able to breathe through, although her speech from here on will be a bit muffled.
All the symbiote-plants (the trees are just one kind) seem to be sensitive to CO2, so they cover the mouth and nose only after some delay. See my answer below...
Really looking forward to seeing where this goes!