In the pre-Batman television series, Gotham, we were treated to a small but amusing scene between teenager Salina Kyle (Catwoman) and street urchin Pamela (Poison Ivy). Despite Pam’s starvation, she will only eat vegan food even when she and Salina are raiding Barbara’s bountiful pantry brimming with food of all kinds.
I found the scenario quite funny but as Mary pointed out to me, why is Pam eating just vegan food if she’s a plant lover?
At first I was able to justify the situation but the more I think about it the more it was bothering me. Shouldn’t Pam, and in general Poison Ivy, eat meat if she’s a lover of plants? This question is harder to answer than you may think because we rarely see Pam eat, if she does at all, so trying to find direct evidence of her diet is pretty difficult.
Asking this question did not prove very useful…and was probably a bad idea
This question can easily be answered if we are in a more fantastical version of Batman’s world such as the DC Animated Universe or the Arkham video games. In those magically inclined worlds, Poison Ivy’s relationship with plants is so extreme that she becomes part plant herself. Her green tinted skin and her love for sunlight propagates the idea that she may be photosynthesizing energy from the sun.
But Pam’s diet in a real world setting like Gotham or Nolan’s Dark Knight is bit trickier to discern. How can a bioterrorist, who goes stark raving mad when she sees someone pluck petals off of a flower, justify eating a salad? She could go all meat but I couldn’t imagine her justify a carnivore lifestyle since it would support domesticated crops for livestock use.
From “Harley and Ivy” in the Batman: The Animated Series
Thankfully, we witness Pam’s diet in the original Batman: The Animated Series. In the episode “Harley and Ivy,” we see Pam eating a bowl of salad with beet juice. She serves a plate filled with carrots, tomatoes, cucumbers, lettuce, and what looks like the top of some peppers to Harley.
Okay, she eats vegetables, but why? Again, I say, doesn’t she hate the destruction of anything plant related?
Let’s take a step back. What I want you guys to do is separate all sense of logic from reason. Let’s think like a Batman villain. Let’s think like Poison Ivy.
Poison Ivy believes she can communicate to plants. Whether or not this is true is hard to say but one thing for sure is that she believes it. I believe she has found plants, by communicating to them, who were willing to be eaten by her. Her goal in saving plants from humanity can only be sustained if she eats other organisms. I think she has convinced herself that her diet is for the greater good. She can fuel herself by sacrificing a small amount of plants in order to save the greater biosphere. I think in this case, when she eats plants she knows they don’t mind being eaten by her because they have accepted it. A rose with its petals being pulled out, on the other hand, is unnatural and has no overall purpose. It’s similar if you were to slaughter a cow for the hell of it and not for the nutrients it can provide you.
Does she feel bad? Very likely. It’s probably the main reason why she’s trying to become a fully photosynthetic organism. She wants to eliminate that final connection to her humanity and embrace that final step to plant hood. In doing so, she will no longer have to sacrifice plants, by eating delicious salads, to complete her quest of plant domination. And when she does, she and us will no longer have to ponder and worry about her unusual diet.
The Unapologetic Nerd 
I love this topic so much and have talked about it many times in depth: https://thatvegancosplayer.wordpress.com/2016/02/03/poison-ivy-a-vegan-comic-idol/
In the real world, I believe Ivy would be a fruitarian who could also photosynthesize in some forms. A plant based diet does way less overall damage to the environment than incorporating any animal products, and at the end of the day, Pam is a studied scientist who understands the real culprits behind environmental damage: big ag and animal ag.
There are also plants that flourish from others eating their fruit, and picking ripe fruit off such a plant doesn’t cause it harm. Ivy is a big proponent as well as Mother Nature and the natural world, so I feel her goal would be to simply protect it from unnatural sources like mass human invasion.
It makes no sense for her consume any animal products due to the mass about of energy and plants (and water) it takes to make those products. Even a small, “old McDonald” farm would have to use more land and energy to make meat or dairy versus just gardening.
While I can see her get irrationally mad at a cow eating grass, logically she understands the circle of life. Also, how is attacking a cow gonna help? She wants to go after businesses actually causing climate change and clear cutting rain forests, not individuals or animals who she knows has no control or power.
Eating plant food vs meat actually saves way more plants overall. I recently read a Harley Quinn and Batman where Ivy only ate meat and I thought it was silly because effectively eating cows and other animals that eat plants their whole lives kills way more plants and is terrible for the environment
I think the best diet for Poison Ivy would be Fruit, Berries and Wild Game. She harms fewer plants by consuming Wild game, and doesn’t support the cattle industry, and many fruit are created with the intent of feeding animals so their seeds get fertilized. I think this is the best way for her to harm as few plants as possible, and I see no reason for her to avoid consuming Wild Game.
in the most recent incarnation of DC Super Hero Girls (2019), their version of Pamela Isley does in fact eat only meat and is horrified at the thought of people eating plants.