Most of us think of venus fly traps when we talk about carnivorous plants. Experienced gardeners and house plant owners might consider pitcher plants or a few other well-known examples of plant carnivores.
But what about the humble tomato?
You might be surprised to learn that, by some standards, tomato plants are passive carnivores, along with many other vegetable plants we used to think were traditional rather than carnivores.
Of course, we’ve only just discovered that tomato plants don’t have hidden insect-digesting parts. Instead, this is more a case of looking at the plant’s traits differently and seeing the hidden carnivory in plain sight.
Let’s talk about how tomato plants ‘eat’ insects, what that means for caring for them, and what makes a plant carnivorous in the first place.
Tomatoes Are Carnivorous… Kinda
So, this might change the way you look at the tomatoes in your next Caprese salad, but those tomatoes probably benefited from nutrients from insects, just like venus flytrap plants benefit from the flies and other insects it eats.
How does that work?
Well, the trichomes or tiny hairs on tomato plant stems routinely trap small insects, especially aphids. Eventually, as the insects die and dry out, they drop onto the soil around the tomato plant. Over time, those tiny insects decompose and add a lot of nitrogen, carbon, and other essential nutrients to the soil.
But wait, that’s not the same as a venus fly trap or a pitcher plant trapping and digesting an insect, right?
Well, it depends on how you think about plants being carnivorous.
The trichomes on your tomato plants are similar to the trichomes venus fly traps and other carnivorous use to decide whether an insect is trapped or worth digesting. They’re the same structure, and it’s at least plausible that the benefit of trapping insects is part of why tomato plants grow trichomes.
Whether this counts depends on what you think counts as carnivorous plant behavior and whether that behavior can be passive.
What Makes A Plant Carnivorous?
Some carnivorous plants are obvious. Sundews and venus fly traps actively trap their prey. Pitcher plants attract and then slowly digest theirs – or encourage other animals to leave their excrement in the pitcher for essentially the same reasons they would trap insects.
Those obvious acts of predation have evolved about six times in nature and tend to occur most often in plants that live in nutrient-poor regions like wetlands and swamps.
So, do tomatoes count?
Well, yes and no. No one is arguing that a tomato plant is carnivorous like a sundew. Instead, the primary argument is that tomatoes are passive carnivores and that they aren’t scavengers since the plant is the one killing the insects it benefits from.
More details are in the next section.
What Do Tomatoes Do That Could Be Called Carnivorous?
Tomatoes are covered in tiny hairs called trichomes. Those trichomes do several things, including protecting the plant from temperature extremes and UV radiation from the sun.
However, they also serve another critical purpose, trapping and killing small insects.
Chances are this defense evolved partly because aphids, spider mites, and other small insects can cause a LOT of damage when they are allowed to infest a tomato plant, so trapping them in areas they can’t cause harm is a good way to protect the plant.
However, trapped and killed insects usually fall off the plant over time. Once they fall off the plant, they mix with the soil and contribute the same nutrients that more traditionally carnivorous plants get from their kills.
So they’re a trap-and-decompose carnivore. They don’t do the digesting themselves, but they benefit from the result of dead insects.
Are Tomatoes Eating Insects Or Just Benefiting From An Evolutionary Trick?
Many people might think this is just a passive benefit of having trichomes, mainly since tomato trichomes serve so many other purposes.
However, that’s potentially a mode of thought that ignores some of the complex interactions plants have with insects in the natural world.
To clarify, the same people who think that tomatoes might count as a passively carnivorous plant also think that potatoes, cabbages, and many other vegetables might have some of the same passive carnivore.
Whether a tomato plant is truly carnivorous might seem like a silly thing to quibble over, but it’s crucial for understanding all of the interactions in the natural world.
For instance, if tomato plants benefit from dead aphids… should gardeners try to make sure there are some aphids without letting the pests get out of control?
Understanding these evolutionary tricks can help us learn more about the plants we rely on for food and may lead to additional discoveries about how food webs work on our planet.
After all, if plants eat insects more often than we thought, that changes some of our assumptions about how nutrients and energy move through the ecosystem. Plants might be even more powerful than we thought they were.
Does This Change How You Should Care For Your Tomato Plants?
Not really, at least not yet. There aren’t any benefits to adding more insects to the soil, and your garden will naturally attract plenty of insects for your tomatoes. You can still plan your garden the way you used to, including companion planting and treating pests.
After all, the pests you eliminate still end up in the soil the same way those killed by your tomato plants would.
However, it does mean that you might want to ensure your indoor tomatoes are getting a little extra fertilizer since they’re less likely to have this natural source of nutrition.
NOTE: I wanted to be more fun with this one while still getting into the science. Let me know what you think of the tone and pacing, and I’m happy to revise if needed; I know this is a little different from my other writing on this topic.
Hi there, my name is Allie and welcome to my blog; GareningWithAllie!
Much of what you see written here is just our personal experiences with gardening. Along with the content I write here, there is also a unique collection of gardening topics covered by some of our close friends. I hope you find everything you read here to be helpful, informative, and something that can make your gardening journey the most lovely experience ever! With that said, Happy Gardening!