The fact that most carnivorous plants eat insects and other animals is only part of the reason why they offer such a fascination. The real reason, the same exact reason why orchids and cycads and bamboos offer similar pleasure, is that they have such diverse survival strategies and adaptations. Flowers, leaves, root systems: one of the reasons why Venus flytraps come off as quaint or even a little vulgar to serious carnivorous plant enthusiasts is because they’re actually a little dull compared to the subtleties and spectacles among others in the general category.
Three years back, I had dinner with Rick Wyatt, a very old friend I hadn’t seen in close to a decade, and he wondered about the ethics of keeping carnivores by vegetarians and vegans. He was gradually weaning himself from animal-based foods after a serious reevaluation of his life, and I had nothing but respect for his reasons as to doing so. Thanks to popular media portrayals of carnivores, he had an impression of my plants eating huge hunks of vertebrate, and while he had no problem with my new passion, as we’d both met when I was still writing and knew how miserable I was back then, he had concerns.
It turns out that he’s not the only one. Several friends of mine have cut out all but vegetative-based foods from their diets, either for ethical or medical concerns, and they also have concerns with feeding live or dead animals to any plants they might purchase in the future. Others have worries about prey animals getting loose in the house. Still others just don’t want to have to feed their plants if the plants aren’t able to catch prey on their own. All of these are perfectly valid and reasonable objections, and absolutely none of them prevent dedicated vegans from keeping carnivorous plants. It’s just a matter of selection.
The first aspect to consider when picking such a plant is that many absolutely require animal prey for their survival. All carnivores gather and process their prey because they otherwise won’t survive without the nutrients, or if they do, they’ll only survive instead of thrive. Almost all live in marginal environments where they face little to no competition from other plants, and their option to getting the few extra nitrogen and potassium atoms they need is to imitate animals. They aren’t doing this to be perverse; they’re doing this so they can live in areas that won’t be overrun with trees and grasses.
After that, the options are wide open. The first, and most obvious, is that carnivores don’t have to catch animals if they have other sources of nitrogen and potassium. An old trick with show plants is to fertilize them with orchid fertilizer, diluted to one-quarter the normal strength used for most orchids, and sprayed on the leaves as a foliar feed. Some dedicated Venus flytrap owners apply liquid fertilizer to each leaf with a Q-Tip, but this trick generally doesn’t work well with sundews. It honestly depends upon the plants in question, and fertilizing options should be researched before doing so.
Now, if you have issues with using chemical fertilizers, and I’m one of those, we still have options other than using standard organic fertilizers. We can choose carnivores that are only carnivorous in one phase of their life cycle. Australian triggerplants are an excellent choice in this regard: they live in the same conditions as sundews and other carnivores, but only become carnivorous themselves when they bloom. The rest of the time, they’re as carnivorous as a jade plant.
Another option? Terrestrial bladderworts feed upon nematodes and other microscopic soil organisms, and produce fascinating or spectacular flowers (such as with the Utricularia sandersoni shown above). The bladders themselves are invisible to the human eye without uprooting the plant, and they’re taking advantage of one of the most common life forms on the planet. They’re still carnivores, but they’re not openly eating animals.
Utricularia sandersonii
If one’s aversion to animal byproducts is ethical, we still have plenty of possibilities. For instance, the butterworts (including the Pinguicula vulgaris shown here) normally catch fungus gnats and the occasional mosquito on their adhesive-covered leaves. However, recent research suggests that they get a significant amount of their nitrogen through the year from capturing and digesting pollen from other plants. (By way of example, the P. vulgaris below was photographed in the Canadian Rockies just outside of Canmore, Alberta, where pollen from pine trees is a major source of nitrogen for both plants and insects.) We at the Triffid Ranch are just starting experiments with longterm care of butterworts solely with pollen, but occasional very gentle sprinklings of pollen, whether previously gathered by bees or by hand-gathering straight from the plant, are confirmed to be beneficial.
Pinguicula vulgaris
The last option, and one of the most intriguing, involves the purple pitcher plant, Sarracenia purpurea. As with this one coming out of winter dormancy, the old traps and new both have large populations of rotifers and other microscopic organisms living within, and studies at Florida State University suggest that the habitats created by the pitcher plants work so well for the rotifers that they produce more nitrogen than what the plant needs. Considering that this notes that purple pitchers don’t actually require animal prey, instead subsisting on dead rotifers and bacteria, this may help explain why the purple pitcher has a range from Texas up the Eastern US into Newfoundland and Labrador. (In fact, the purple pitcher is the provincial flower of Newfoundland and Labrador for just that reason.) At this point, carnivory turns into symbiosis, as the pitchers become homes for many other life forms, and their shed skins and waste become food for the rotifers and for the plant.
Sarracenia purpurea
With these options, those with objections to consuming or processing animals can still keep carnivorous plants, and keep them healthy as well. It’s all a matter of options, and offering them the conditions under which they best survive. Everything else is negotiable.