Part of the story is going to revolve around a group of plant characters who are scavengers. They prey on other plants and use their body parts as armor and weapons.
Most of the architecture is made out of metal, plastic and glass but is organically shaped. Some of it is shaped like trees. They don't use a lot of paper or wood since some of their friens are trees.
Hazel riding a plant creature. Like in Narnian trees some plants speak and can think and some can't.