Dr. Pamela Isley began to create Animal-Plant Hybrids in a South American jungle laboratory that was funded by Wayne Enterprises. Her success in trying to complete and perfect the hybrid was interrupted constantly by the ambitious, but treacherous, Dr. Jason Woodrue. The toxic chemical, labelled "Venom" by those two doctors, was stolen from Isley's lab and was used in Woodrue's experiments to create the chemically altered human being known as "Bane". After she discovered Woodrue's experiment during an auction to world terrorist leaders, Isley refused to join Woodrue in his financial endeavors. Woodrue attempted to dispose of Isley by pushing her into a table of various poisons, toxins, and chemicals, but instead, caused her transformation into "Poison Ivy".
Ivy moved from the jungles of South America to Gotham City and took her dangerous Animal-Plant Hybrids with her, that were contained within tiny seeds. After she took over the Turkish Bath House from the Golums in Gotham, Ivy used the seeds and created a lair of freakishly overgrown plants, called "Paradise" by Ivy herself. Ivy continued to experiment with her hybrids, and showed a half-snake half-plant hybrid to Mr. Freeze when she introduced him to her lair. Her plan was to overrun the entire world with her Animal-Plant Hybrids after Freeze had frozen all life with the Gotham Observatory Telescope.
The hybrids were later used against Batman and Robin when Ivy was able to seduce Robin to her lair. After Robin revealed his treachery, Ivy pushed him into a pool of lily pond vines which attempted to drown him. Batman was then attacked by ceiling vines after he tried to stop Ivy's escape. Yet, after Ivy's defeat by Batgirl, Robin was let out of their grasp and Batman cut his way out of the vines that held him. With Ivy incarcerated at Arkham Asylum, it was assumed that the hybrids were removed and destroyed, or else died without their mother.
Powers and Abilities
The Animal-Plant Hybrids were incredibly strong and were incredibly self-aware plants: they were a chemical combination of both plant life and animal instinct. Isley said that she had created them to "fight back" and used them to attack the Dynamic Duo. Though they seemed to be under Ivy's control, it was ambiguous to whether she had entire control over them. They certainly seemed to respond to Ivy however, such as the incased snake-plant hybrid and the plants in her lair. They created the seductive atmosphere when Robin entered the lair (at Ivy's whim, lowered the curtains of vines behind him and opened the leaves of her throne and revealed her) and yet, attacked Robin and Batman aggressively when Ivy was riled at Robin's betrayal. However, they seemed to react violently against Ivy when she was finally beaten by Batgirl; Ivy's "flower-bed" crushed her when she was kicked back into it, the reasons for which were unknown.
They seem to be incredibly strong, and were able to lift Batman and crush Robin, and yet, their poisonous abilities remained unknown despite the implications of lethal toxins and chemicals. Several variants of the hybrids were seen, and the clearest distinction was the snake-plant hybrid that was shown to Freeze and the largest was the 'flower-bed' that Ivy lain on in her lair. The 'flower-bed' itself had unknown weapons, which appeared to crush Ivy after she was defeated, but also implied that it could drain its victims (Ivy appeared significantly weakened in her final scene at Arkham Asylum, which implied that the attack may have had something to do with it). As the only hybrid that exhibited any form of violent behavior to Ivy, it was ambiguous to why it did attack; it was possibly a defensive mechanism to being landed on, drain the seduced Robin in a deadlier trap, or that the hybrids rebelled against Ivy.