[The mun's guess is that it's some kind of psychometry and Apollo is confusing the auras of the plants with the plants having intelligence, but that's just headcanon. The concept is just thrown at the viewer and then never mentioned again, so I have to try and justify this mess somehow.]

They don't have the same kind of consciousness as animals, but they know what goes on near them. Their stories are a bunch of ideas and feelings and pictures all clumped together and you have to put them all in order to see what's happening. Animals think more like humans do.