The Plant Creatures were biogenetically creatures created by Poison Ivy.
History[]
After she "reformed" and "married" her doctor, Steven Carlyle, Poison Ivy secretly created plant-based human-plant hybrids of the real Carlyle and "sons" named, Chris and Kelly, who were really girls and sedated the real Carlyle in a tank.
The creatures look like kids during the first stage, in the second stage they are adults looking like Steven and in the third stage, they transform into green monsters with long thin sharp cactus-like claws. Their lifespan is similar to a rare flower which results in them burning themselves out, and they melt into a puddle of goo.
Ivy sent a green monster to attack and poison the wealthy men of Gotham City and steal their money for her experiments. At first, Batman and Commissioner Gordon thought Ivy was the culprit, but she feigns innocence. One night, the monster kidnaps Dick Grayson for ransom, and orders Bruce to bring the money to the pier. After Bruce brought the ransom money in exchange for Dick, the monster throws him into the sea, but changing into Batman, he defeats the monster by cutting his claws with a Batarang, sending the monster into retreating.
After freeing Dick, Batman learns that Steve Carlyle never had sons, Chris and Kelly are in fact girls, and Carlyle's ex-wife gained custody of their daughters. Arriving at Ivy's house, Batman and Robin find Ivy's secret lab, freed the real Carlyle and discovered Ivy's experiments. When Ivy appears and captures them in vines, she explained her plan to her captives, and sends her creatures to kill them. However, Batman frees himself, Robin and Carlyle from the vines, but as they made their escape, they were confronted by the fake Carlyle, Chris and Kelly.
As Robin keeps them at bay with hedge clippers, Batman activates the greenhouse's watering system, dousing the creatures with weedkiller, which dissolved them into blobs of goo. When Ivy confronts Batman, she coughs and starts melting. As she collapses, Batman catches her in his arms, and he watches as "Ivy" melts into a puddle of green glob, revealing herself to be another plant copy, while the real Ivy escaped Gotham City by airplane. Luckily, the police found an antidote and cured Ivy's victims.