Who is Rangers from Uglies and what is their importance?

Tally meets a group of Rangers on her trip to the Smoke. These Rangers are pretties whose job it is to control the growth of a certain species of orchids that have been genetically engineered to live anywhere. The Rangers burn these flowers in an attempt to keep them from crowding out other indigenous plant life. The Rangers fly helicopters taken from ruins of Rusties' cities and repaired with replicated parts.