06 April 2010

Carnivorous Plant May be Vegetarian (but not vegan). Eating them, not so much.

A cultivated Nepenthes rajah
Note:  You also may be interested in another post:  A Partial List of Edible Carnivorous Plants and Fungi.

I read recently about a new study: Trap geometry in three giant montane pitcher plant species from Borneo is a function of tree shrew body size. The study describes how one of the largest carnivorous plants in the world, Nepenthes rajah, may have evolved not to eat animals, but to eat poo. And you thought that it was just a coincidence that it looks like a toilet. Though I guess in Borneo they use squat toilets, but whatever. The study shows that the distance between the 'seat' and a gland that extrudes a nectar-like substance on the 'lid' is the exact height of a local tree shrew, Tupaia montana. Now before you think they just were measuring animals at random, these critters poop where they eat (despite any advice to the contrary), to mark their territory and keep away any competitors. However, when feeding from this pitcher plant, the feces fall in the 'bowl' of the plant, and the plant becomes a coprophage.  And if anything needs a picture it's a tree shrew pooping in a toilet plant, so if anyone has one, please send it my way.

I'm sure that N. rajah is not picky about what ends up in it's bowl for it to 'eat,' so it's not really 100% vegetarian (some treeshrews and mice do fall in and die).  It does make the whole diet nomenclature seem kind of silly.  'Vegetarian plant' sounds weird to me (though admittedly 'vegetarian' is not a very specific term to say the least).  Especially for eating feces.  And especially since I put manure on my vegetables in my garden, and they 'eat' that.  Sure a special organ made to trap animals and/or animal byproducts is a little more advanced than just sucking up whatever from the roots, but many plants excrete enzymes from their roots to digest organic material before it is absorbed by the roots.  But again, that is even less specificity than just having a bowl for stuff to fall in, and definitely less than having one set up to be a treeshrew rest stop. 

Capsella bursa-pastoris
Would you eat a carnivorous plant?  How about a vegetarian plant?  Or a hypothetical vegan plant?  The only example of the former that I've seen for sale as food is the possibly protocarnivorous plant Capsella bursa-pastoris, commonly known as shepherd's purse.  I have eaten this before I knew what it was, in frozen steam buns I got at an East Asian grocery store.  I now avoid it, because it's just as easy to do so, and then my conscience is clear.

Another edible protocarnivorous plant is Proboscidea spp., or devil's claw.  Here is a blurb on it from Southwestern Endangered Aridlands Resource Clearing House:

Proboscidea parviflora seed pods
Cultivated by many Southwest tribes, the seed is rich in oil and protein.[...] Dried seeds can be peeled and eaten[...]. The young fruits, when still tender, can be cooked as an okra-like vegetable.
Drosera rotundifolia
Proboscidea are also used to make baskets, which you may or may not consider vegan.  I read some chatter that that Sarracenia purpurea (purple pitcher plant) and Drosera rotundifolia (common sundew) are used in traditional medicines, and the latter possibly in some modern ones.  Would it be ethical/vegan to use these medicines?

I'm not sure if N. rajah is edible, or even if anyone has tried eating it, though I can't see how the treeshrews are being particularly exploited.  Undoubtedly if the toilet plants were commercially cultivated I can imagine some horrible fate for the treeshrews akin to foie gras ducks.

So as always, let me know what you think.  Where do you draw the line?



  1. Interesting! Obviously you can control what you use to fertilize your plants at home, but how do you deal with commercially farmed produce? I get the impression that a lot of farms use fish "by-products" or bone meal to fertilize. Here at the farmers' market I've seen farms that advertise that they use only vegetable-based fertilizers, but I don't see how one would know for supermarket produce.

  2. NaRose, I think that's one of those things that gets a blind eye typically, since it would be nigh-impossible to distinguish in many circumstances. Eventually I'd hope there could be some kind of labeling, but that may not be until after they start listing things like wax on cucumbers and dyes in beef.

  3. Well, at least during the summer here I can get my produce local & my veggies wax-free :-)

  4. I should qualify this with I'm not vegan, but I am vegetarian.

    I would eat anything that doesn't fall under the animal kingdom (mushrooms/yeast are fine). I would guess that for a vegan, anything that doesn't fall under the animal kingdom and that isn't produced directly by any organism in the animal kingdom.

  5. Ankit:
    So the transitive property does not apply for you? I.e. for you if an animal is eaten by a plant and then eaten by you, that doesn't count as you eating the animal?

  6. I would definitely had no qualms about eating a plant that eats animals.

    It may tap our "contamination" inference system (the one that says "avoid pollution at al costs; it can be invisible, beware!"), as when people refuse to eat a sterilized cockroach or feel disgusted even thinking about eating from a brand-new toilet seat (hasn't been used). This pollution-avoiding module may be active when you speak of "transitive properties", in case some hypothetical vegan really does feel bad about eating the plant in question. But isn't this logic an infinite regression? Where do you stop avoiding the dead animal "essence"? If it just dies in the woods it is decomposed by bacteria and other micro-organisms, which in turns sets up a food chain that inevitably ends up with some nutrients that "lived through" some animal's life cycle.

    Great post, by the way. Very beautiful looking plant.



  7. Diego, I take it that if you are veg*n, you are for health reasons rather than ethical ones?

    If you are not vegetarian, would you eat doctor fish or chin chin yu that had eaten human skin? Or how about fish that had possibly fed on human corpses? The latter issue having some prominence in 2004:


  8. Not at all. Why do you think I'm vegan for health concerns? I'm first and foremost an ethical vegan.

    So, I can't answer the latter question because I won't eat fish under any circumstance.

    I would eat a plant that eats humans. Of course. What's the problem? I fail to see the connection with ethics. The only relation I see is the one I exposed on my previous post, regarding the "intuitive" notion of contamination common to humans everywhere (and applied to vegans in this case).

    Best regards

    BTW, this is me, Diego. Just borrowing an already opened account on this pc.

  9. I don't understand what that has to do with your conscience. You think that eating meat increases one's sentience and ability to feel, and therefore that eating a carnivorous plant would be harder on your conscience than eating a vegetarian plant? Very confusing. I suspect you are joking, but nevertheless...

  10. Hello, Veg Lab Rat. :) I'm really glad I found your blog, as we appear to be kindred spirits.

    I'm a vegan paleontology student, and actually have a practical question for you. I'm facing a battery of university biology classes coming up, and suspect that my objection to most animal testing will present me with some hurdles. I'm more than willing to fight for my right of conscientious objection, but I'm wondering if you went through a similar experience, and if so, what advice you could offer in dealing with deans, administrators and professors.

    Or did you veganism come after you made it through school?

  11. If you eat a carnivorous plant, aren't you saving future animals from being killed by it? Unless you're talking about something that is commercially farmed and deliberately fed animals (which doesn't sound too efficient to me), I fail to see an ethical quandary.

  12. Sorry for the slow replies.

    Luella: If the goal is to harm less animals, then buying (and spending money to propagate) plants, animals, etc. that kill animals, then shouldn't your conscience be responsible for those animals dying?

    Anna: I think more animals would be killed if shepherd's purse or oyster mushrooms were farmed than if they were gathered from the wild. With a farm, the carnivores wouldn't be there otherwise, so you have more deaths. If you gather from the wild, then I suppose you're saving animals.

    Robert: I did raise a stink, and had small victories, but i still couldn't avoid it all. And once I was known as a conscientious objector, my reputation suffered in the academic circles. check your university guidelines, especially religious exemptions. Also, contact your school's animal rights group and see if they know the loopholes. good luck.


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