Ivy

The Ivies were BOWs created by the Umbrella Corporation. They resembled enormous, vaguely humanoid plants that were capable of locomotion. They were apparently created in the hidden laboratories beneath Raccoon City and spawned from a massive plant that grew in the facility's main stairwell. Normally, the Ivies would spit a corrosive yellow acid from their four-flapped "mouths," but when exposed to anti-BOW gases, they tended to mutate, and their spit became poisonous.