In the early stage of infection green spirals appears on their skin, similar to spot pattern at Stage 1, and they can absorb other peoples just by touching them. However high level evolved can resist the absorption with their resistance to the virus.
Infected humans gain strength the more they consume, similarly to an Evolver, but relying on the pollen instead of gathering viral energy only reinforce it and accelerate their taking over. Infected humans seems to be used only as transportation and incubation of new plants, as well as to disrupt and infect cities, survivor bases and safe zones. Zombies target them due to the viral energy present in their bodies and ends up infected as well.
Once the plants sprout, they use the body of their host to eat more humans and release new spores while slowly draining it. Sometimes those who get infected by the plant only lose control of their body and keep a clear state of mind. Finally the body dies or becomes bait in the Infected Plant Corridor. If the host is killed while the plant is too little, she will die with her host.
If they eat a granule of Flower Resin before being completely infected by the pollen, or if they reach Stage 3, they can revert the mutation. If they get bitten by a common zombie, they turn into an Infected Zombie.