Viridian: Quicksilver, Book 1 (Unabridged‪)‬

A virus has swept the world, turning polluting, wasteful humans into peaceful human/plant hybrids called Verdans. More and more people choose the Verdan way, till only a few humans are left. But then the Cultivars rise - terrifying, cruel Verdans, genetically modified to become brutal warriors, who are determined to wipe out what remains of humanity. They turn the Verdan dream into a nightmare. And at their head is the lethal Viridian....