Plant 43 are bipedal green plants with arm-like extensions. Some "Ivies" have green heads while others have pink heads. Sentient, or close to sentience, their main method of attack is to whip their target with their vines. They can also attack at range by spitting acid. If the prey gets too close, the plant is able to grab them with their vines and spit acid over their bodies. In some cases, the monster pretends to be dead, but would still whip its target if they walk too close by it.
The experimental anti-B.O.W. gas "P-ε" cannot defeat P-43 and will instead cause it to mutate. This mutated form is physically tougher than its original counterpart, and its acid has become poisonous to humans.