[HN Gopher] After millions of years, why are carnivorous plants ...
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After millions of years, why are carnivorous plants still so small?
Author : gmays
Score : 189 points
Date : 2025-06-13 20:04 UTC (5 days ago)
(HTM) web link (www.smithsonianmag.com)
(TXT) w3m dump (www.smithsonianmag.com)
| leoedin wrote:
| Larger animals tend to more intelligent - presumably there's a
| natural limit to the size of prey a carnivorous plant can
| reliably catch from a static location.
| IAmBroom wrote:
| Counterpoint: mice and at least one monkey baby have died in
| pitcher plants in the wild.
| jonplackett wrote:
| Isn't this still just the original point though, mice ain't
| that big!
| IAmBroom wrote:
| We're using different criteria for "big".
| imtringued wrote:
| A lot of pitcher plants evolved to be a toilet for shrews.
| HelloNurse wrote:
| Larger animals are highly undesirable prey because they tend to
| be able to free themselves from a carnivorous plant (low
| value), with a high probability of severe damage to the plant
| in the attempt (high cost): they can just walk or climb away,
| but also involuntarily break a stalk with their weight, tear
| open a sac with talons, rip away slowly regenerated adhesive
| parts, eat something that should be dangerous, and so on.
| almosthere wrote:
| We haven't had an unscheduled total eclipse of the sun with
| people singing in the background yet.
| colecut wrote:
| have they tried feeding them alllll niiight loooong
| IAmBroom wrote:
| OK, I wrote my theory, and then read the article: same.
|
| But I will add that a commercial grower of venus flytraps once
| got curious, and took a few thousand cloned plantings, growing
| them in a variety of conditions. _As soon as the soil became
| nourishing_ , the plants would die. Post mortem seemed to
| indicate their roots were fungally attacked.
|
| So: plant adapts to living in a food desert (not an actual one,
| of course; it has to be wet for the carnivory to work, as the
| article points out). Plant gains weirdo digestion abilities, but
| at the same time, it no longer needs expensive anti-fungal
| defences - because the ground isn't rich enough to support
| parasitic fungi.
|
| Then: human adds the nutrients back in. Boom! The ordinary fungus
| in the air, which has a tough time invading grass or tree or
| tobacco or pepper roots (because they have extensive defences,
| like capsaicin), lands in the rich soil of pretty-much helpless
| flytrap roots, and has a buffet.
| NegativeLatency wrote:
| Sorta similar with a lot of plants I imagine, we planted a
| Madrone tree and it's very tempting to want to water a small &
| new tree but they can also get root issues if the ground is too
| wet or doesn't drain well enough. They're highly adapted to
| living on the sides of cliffs.
| ge96 wrote:
| I've been trying to grow a mango from a seed for so long. The
| roots always get hit by black fungus and it dies off. Tallest
| I got one to grow was about 10"
| thatcat wrote:
| Try adding some natto innoculant to the seed
| tmoertel wrote:
| For the _Bacillus subtilis_?
| pantalaimon wrote:
| Same with Lychee, after a bit the leaves all start getting
| brown from the tip and die off.
|
| Avocado on the other hand grows like a charm.
| kakapo5672 wrote:
| Weird. We just planted a madrone too.
|
| Labor of love (beautiful trees), but they are very iffy trees
| to get going. I did attempt to help things along by putting
| lots of madrone duff with it, so as to try to get the right
| biota.
| tetha wrote:
| We recently had this discussion about house plants as well.
| The unexpected part is: Too much watering hurts more than too
| little watering. Especially with bad drainage.
|
| If the watering is on the too-little side for the evaporation
| and plant size going on, well, the plant will look a little
| sad for a bit. Then you water it, and it goes back up and
| looks happy again. This is a situation plants regularly deal
| with in the wild - drought - and they have adapted to it.
|
| If you water too much, especially with bad drainage, there
| will be stagnant water in the pot, roots rot and the plant
| dies with little recourse.
|
| So now I make sure my pots can drain, take my plants outside
| once or twice a week, absolutely drown their soil and let
| that drain for an hour or two. This way, the soil becomes
| saturated without stagnant water and... some of these plants
| are reproducing and growing at unreasonable rates for the
| amount of effort placed into them.
| khafra wrote:
| I hope there's a mad scientist somewhere, making a cross-
| genetic venus flytrap that also produces capsaicin and
| nicotine.
| IAmBroom wrote:
| Genius!
| Terr_ wrote:
| So it draws people in with the promise of a nicotine fix,
| and then sprays them with mace to stop them from struggling
| free...
| dyauspitr wrote:
| And is also selecting for size. If other plants are anything
| to go by we can probably increase the size three fold.
| dylan604 wrote:
| Wait, I've seen this movie. I'd suggest not trying this if
| your name is Seymour
| konfusinomicon wrote:
| throw thc in and that will make one hell of a hot tamale
| flir wrote:
| Hm. What about hydroponics? Lower risk of fungal infections
| there.
| belval wrote:
| In a clean room maybe, but honestly hydroponics usually makes
| things like that worse, not better and I say that as someone
| who's had a set up for over ~5 years at this point.
|
| At the end of the day it's a pit of water with nutrient that
| is usually somewhat warm. You can control algae with hydrogen
| peroxide but there is always some water that will stagnate
| somewhere and lead to some mold level. It's really best to
| grow plants with a clear growth => harvest cycle so that you
| can periodically re-sanitize everything.
| blacksmith_tb wrote:
| I think that's a double whammy, not only are the fungi ready
| and willing to use those extra nutrients in the soil, the
| carnivorous plants have in many cases lost most of their
| unneeded-in-poor-soils ability to absorb the nutrients. That's
| why you can feed your flytrap tiny bits of hamburger (or maybe
| tofu, not sure if the amino balance matters unless that's all
| they're getting?)
| kragen wrote:
| 98% of grass or tree or tobacco or pepper roots are invaded by
| fungus, and cannot survive in soil if they are not invaded by
| fungus. Rice is one of the rare exceptions. Having their roots
| invaded by fungus is probably what enabled plants to colonize
| land in the first place.
|
| https://en.wikipedia.org/wiki/Mycorrhiza
| nyeah wrote:
| tl;dr Basically a lot of sorry excuses.
|
| If you're a plant, don't buy into the negativity. Work your way
| up the food chain. If you eat it, then it's your food.
| bell-cot wrote:
| As soon as a carnivorous plant gets big enough to be eating young
| mammals, it hits the Mama Bear barrier. With motivation, even a
| tiny mammal can do an enormous amount of damage to a plant.
| hirvi74 wrote:
| Some carnivorous plants do eat mammals. Though not primarily,
| some pitcher plant species have been known to eat mice, for
| example.
| _tom_ wrote:
| You are assuming that they haven't.
|
| Brambles can trap sheep, benefiting from the sheep as fertilizer:
| https://www.youtube.com/watch?v=mrGobnZq83g
|
| Falling coconuts can not only kill people, but probably kill far
| more small animals, again benefiting from them as fertilizer,
| ethbr1 wrote:
| Came to HN for tech news, left with a disturbing realization
| that coconut trees might be low-key carnivorous.
| username135 wrote:
| Right?!
| __MatrixMan__ wrote:
| If it's a fun kind of disturbing, and you like SciFi, you
| might enjoy Semiosis.
| Affric wrote:
| If plants moved faster we would be absolutely terrified of
| them.
| athenot wrote:
| Let's not be too hasty...
| signalToNose wrote:
| The Day of the Triffids
| rcarmo wrote:
| Came here for this comment.
| loa_in_ wrote:
| Attack of the killer Tomatoes!
| bregma wrote:
| He means fruits.
| doesnt_know wrote:
| Going down that line of thought... Cocunuts naturally selected
| for harder shells because those killed, creating more
| fertilizer ...
| kragen wrote:
| Coconut husks are fairly soft. About like a pumpkin. They're
| only dangerous because they're so large and heavy.
| trgn wrote:
| Dont they clank!
| hinkley wrote:
| Maybe poisonous plants aren't always protecting themselves.
|
| "None of you seem to understand. I'm not locked in here with
| you. You're locked in here with me!"
| pauldraper wrote:
| The kill rate of coconuts cannot be high.
| zimpenfish wrote:
| [0] lists 28 documented cases - if we ignore the 5 before
| 1943 (probably not reliable records), that gives 23 in just
| over 80 years or roughly one every 3.5 years (although you'd
| expect that to have increased over time as more people live
| or tourist near the trees)
|
| Of those 23, 5 were infants (<3y), 1 was killed by 4
| coconuts, 1 was killed by a bunch of 57 coconuts(!), and 2
| were accidentally killed by their harvesting monkeys.
|
| [0] https://en.wikipedia.org/wiki/Death_by_coconut
| nottorp wrote:
| > 1 was killed by a bunch of 57 coconuts(!)
|
| I'll raise you this:
|
| https://www.bbc.com/news/world-europe-66429342
| dyauspitr wrote:
| I was in south India for about a month and I heard of 1
| person dying from a coconut during that time period and heard
| it wasn't unheard of. Not a lot of people die but plenty of
| folks get injured.
| gbraad wrote:
| The size of insects has decreased over time, correlating with a
| drop in atmospheric oxygen levels. Maybe this has also happened
| to carnivorous plants?
| moate wrote:
| As the article points out: If conditions exist for "high-
| quality plant growth" (correct light, soil, moisture, etc)
| then plants don't make weird adaptations like eating
| things/water-conservation methods.
|
| However, if those conditions DON'T exist, then it's hard for
| plants to get very big.
|
| There's also this: the larger a moving creature you're trying
| to capture, the more resources you need to invest in the
| trap. Bladderwort exists everywhere because it's easy to trap
| small/microscopic things. Giant bear-eating plants exist
| nowhere because consistently trapping a bear with just
| leaves, sap, and stems is really fucking hard.
|
| At a certain point, the plants reach an equilibrium where the
| effort is worth the end result, but diminishing returns if
| they got larger.
| lambdasquirrel wrote:
| If you want to speculate about that, then how about the bamboo
| die-off cycle? Imagine if you lived in the PNW or Appalachia,
| and every 120 years the entire side of a mountain launched an
| army of hungry rats at you. Starves all those cute smug "panda"
| gluttons too.
| imoreno wrote:
| Wouldn't animal scavengers pick the carcass clean long before
| it rots?
| kragen wrote:
| That still counts if the scavengers poop nearby.
| imoreno wrote:
| Usually, animals move around while digesting. They don't
| just eat the food, immediately digest it, and poop on the
| spot like a cartoon.
| yesbabyyes wrote:
| I've visited Lady Musgrave Island in the Great Barrier Reef. It
| is covered with trees called "the grand devil's-claws", the
| seeds of which are barbed and sticky. The seeds stick to the
| wings of birds eating seeds, and so they can spread across
| islands.
|
| However, a visitor to the island will soon notice lots of dead
| birds on the ground. There are no predators or scavengers, so
| the birds lay there decomposing.
|
| Thus, the trees use the birds not only for reproduction, but
| also for food. It's a carnivorous forest out there on the reef.
| knowitnone wrote:
| this is a secondary mechanism. Falling branches kill and
| therefor get fertilizer.
| Sevii wrote:
| Plants not being able to chew or tear their prey is a big
| disadvantage.
| mlinhares wrote:
| Not if you're prey. i'd rather not have more stuff trying to
| eat me :P
| IAmBroom wrote:
| Baleen whales seem to do just fine without it.
| bilsbie wrote:
| A related question is why plants in general can thrive on such
| tiny amounts of protein. (Nitrogen)
| IAmBroom wrote:
| Simple. They don't need that much nitrogen.
|
| I'd be surprised if your tomato plant "ate" a whole teaspoon of
| fertilizer in its entire growing season.
| chrisco255 wrote:
| > Some large carnivorous plants are alive out there, but none is
| big enough to make a meal out of you.
|
| Clearly these researchers have never been to the Mushroom
| Kingdom.
| signalToNose wrote:
| Mushrooms technically are not plants
| jijijijij wrote:
| ,,Technically"... talking kingdoms :D
|
| Like, an orca is more fish, you are more fish (or fungus for
| that matter), than a mushroom is a plant.
| hinkley wrote:
| We are more mushroom than plant as well.
| 01HNNWZ0MV43FF wrote:
| Plants technically are not mushrooms
| https://en.wikipedia.org/wiki/Piranha_Plant
| Nevermark wrote:
| I would have thought that plants which ate neighboring plants,
| for their easily accessed nutrients and to protect their own
| access to sunlight, water and forest nutrients, would be
| pervasive.
|
| I have heard of chemical/strangling/parasitical type competition.
| The banyan tree is territorial, for instance.
|
| But we would need another name, other than territorial,
| carnivorous or vegetarian, to describe plant predators which
| overtly, actively fed on the physical structure or leaves of
| fellow plants.
| olau wrote:
| I think the problem is that then you need two energy harvesting
| systems, and there's not just that much to eat nearby.
|
| I guess to effectively live a long life by eating other stuff,
| you need to be able to move, or what you eat need to be able to
| move to you.
| IAmBroom wrote:
| Nah. Eating and reproducing lots, fast, is a viable means.
| See: much of the fungi kingdom.
|
| I suppose you could view the passive offspring dispersal
| system (wind, current, animal digestive tract, raindrops,
| etc.) as a form of intergenerational movement.
| adrian_b wrote:
| There are many parasitic plants, like the well-known mistletoe,
| which eat other plants. Unlike mistletoe, some of the other
| parasitic plants have given up completely on phototrophy,
| depending only on the nutrients sucked from the host plant.
|
| It is likely that there are much more parasitic plants than
| carnivorous plants.
|
| Plants that feed on other plants must do it similarly to a
| fungus, by penetrating them and growing into them a root-like
| organ, for sucking their fluids.
|
| A plant could not bite and chew another plant, because, like
| the fungal cells, the plant cells have abandoned their
| ancestral animal-like mobility, by covering their cells with
| walls made of cellulose, which prevent cell mobility. While
| there are a few plants capable of infrequent fast movements,
| like the Venus flytrap, they use special tricks for creating
| tension in an elastic structure, like when drawing a bow, which
| would not be suitable for sustaining a sequence of movements.
| Nevermark wrote:
| > A plant could not bite and chew another plant, because,
| like the fungal cells, the plant cells have abandoned their
| ancestral animal-like mobility
|
| I would think capabilities like that would be recoverable, if
| the biological economics worked.
|
| But your point that parasitical plants continuously live off
| other plants, i.e. they essentially farm them, resolves that.
| Given victim plants can't run away, their metabolisms are
| worth far more than any one-time resource extraction.
| BartjeD wrote:
| Rent seeking economy = parasitism
| musicale wrote:
| I guess there are still some things that we can be grateful for.
| cyberax wrote:
| OK, let's see. You're a plant, so you have photosynthesis. It
| allows you to tap around 5W (averaged out) per square meter of
| foliage by just AFK-ing. Your major need: water, you have to
| evaporate it for the photosynthesis to work. But it's not a
| problem in your habitat, there's plenty of water available.
|
| You also need nitrogen, phosphorus, and other nutrients, but
| comparatively little of them. Nitrogen is the toughest one. This
| is the one that you can easily get from animals, though. So you
| can evolve a complicated mechanism to trap small animals and
| digest them for nutrients. It also provides you with a bit of
| energy, but it's completely immaterial compared to
| photosynthesis, so you don't even bother evolving all the
| complicated protein-to-glucose pathways.
|
| Now, you want to grow bigger. How would you do it? Energy is not
| an issue, the photosynthesis provides plenty of it. But you need
| to trap more or bigger animals, and that's an issue. There just
| aren't that many of them, and you can't just get away with simple
| traps anymore.
| jijijijij wrote:
| Is nitrogen really the bounty, not phosphor? I imagine nitrogen
| fixation is basically the same problem everywhere, equally
| distributed through air, but phosphor depends on geological
| processes, depends on the mineral make of the soil. If phosphor
| gets depleted, you have two options: Wait for mountains to grow
| and shed some, or indulge in someone else's DNA and ATP. Maybe
| the acidic soil makes uptake harder, or aids wind and water
| erosion?
|
| Looking at my spotted windowsill, if I was a plant on an
| evolutionary adventure, I'd befriend some spiders and turn my
| crown into a cotton candy guano cloud. I'd rather have the
| animal predators do the work and then have them shit in my yard
| for the nitrogen and phosphor. You only need twigs and then
| some bioluminescence or stink to help those spiders fill their
| nets.
|
| Have a fungus rot my legacy core wood so an owl can defecate a
| hectare of mice and squirrels right into my tummy. Or you look
| all mighty and judgmental so these funny naked apes drench your
| soil in the blood of goats and their youths. Is that still a
| thing?! What about instagramable forest cemeteries? Heard about
| the tree toilet TikTok challenge? So fun! Super healthy and
| natural too.
|
| Now thinking of it, I wonder how many plants encourage animals
| shitting and dying in their yards. Maybe it's not deterrent,
| but enterotoxic payment options?
|
| I guess, unless your objective is to grow impractically large
| fruits, because your human creator couldn't keep it in their
| pants, for most plants in most places, neither phosphor nor
| nitrogen side hustles are really worth the effort.
| cyberax wrote:
| Yep, nitrogen is the limiting nutrient in swamps. It can be
| fixated only through biological means, while phosphorus is
| produced by weathering rocks. Nitrogen fixation is suppressed
| in swamps, while phosphorus is typically still available from
| the inflowing streams.
| IAmBroom wrote:
| Thank you. TIL.
| IAmBroom wrote:
| > Now thinking of it, I wonder how many plants encourage
| animals shitting and dying in their yards.
|
| All it takes is to make your forest more attractive to bears
| than the Vatican City is.
|
| Bears are notoriously suspicious of ritualized worship, so...
| low-entropy solution achieved.
| hinkley wrote:
| They don't fit into the pews. Humans design them to be
| inaccessible to bears. It's discriminatory. The cats stay
| away because they get bored easily by people talking about
| themselves or other people instead of about cats.
| zimpenfish wrote:
| > then have them shit in my yard for the nitrogen and
| phosphor.
|
| Nepenthes Lowii says hi.
|
| "However, pitchers produced by mature N. lowii plants lack
| the features associated with carnivory and are instead
| visited by tree shrews, which defaecate into them after
| feeding on exudates that accumulate on the pitcher lid."
|
| [0] https://royalsocietypublishing.org/doi/abs/10.1098/rsbl.2
| 009...
| TheOtherHobbes wrote:
| I bought a tiny Venus Fly Trap once, left it in the kitchen, and
| went away for a weekend.
|
| When I came back the kitchen was buzzing with flies, and the
| plant had literally gorged itself to death.
|
| This was extra impressive because none of the windows were open.
| It had somehow leaked attractant scent through gaps I didn't know
| existed and the flies - not exactly numerous where I was - must
| have been aware of it from hundreds of yards away.
|
| Point being the plants may be small, but they can be very good at
| what they do.
| jcalx wrote:
| Reminds me of a semi-plausible mechanism for carnivorous flora
| from this [0] Worldbuilding Stack Exchange answer by ckersch:
|
| > Bonegrass is a white fungus which grows in wheat fields. Most
| of the time, the bonegrass fields are normal wheat fields,
| indistinguishable from other wheat fields except for their
| exceptionally high yields and relatively low numbers of animal
| inhabitants. Of course, this entices lots of animals, large and
| small, to move into the area. Populations boom, fueled by the
| seemingly unnatural abundance of the wheat.
|
| > And then the bonegrass blooms. Overnight, huge mycelial mats
| below the wheat fields become active, with white fungal growths
| growing up the stalks of the wheat plants, using their stalks for
| support. Then, simultaneously across hundreds of square miles,
| the bonegrass releases its paralytic spores. Within 12 hours, the
| wheat fields become pale, white places of death. The fungus then
| begins to grow over the paralyzed creatures, flooding their body
| with neurotoxins that keep them immobilized until they die from
| dehydration over the next few days.
|
| > The dead animals quickly break down, broken apart by the
| fungus. As suddenly as the bonegrass grew, it will then die back,
| shrinking back beneath the earth, where it will slumber as the
| land above it slowly repopulates, drawn by the seeming gaia above
| the soil, and unaware of the horrors slumbering beneath...
|
| Scary stuff. Symbiotic plant-fungi or plant-bacteria
| relationships seem like plausible mechanisms for "carnivorous"
| plants, even if it's not "plants directly eating people" a la
| Little Shop of Horrors. There are more good answers with a
| similar premise under the same SE question.
|
| [0]
| https://worldbuilding.stackexchange.com/questions/38354/how-...
| halflife wrote:
| If you liked this you should watch the animated series
| Scavengers Reign.
|
| It's about astronauts crash landing in an alien planet, where
| the flora and fauna have a symbiotic relationship, and what
| happens when humans appear.
|
| Fantastic show.
| darkhorn wrote:
| https://www.youtube.com/watch?v=RuzLXxbGc4c
| imoreno wrote:
| >Most of this carnivorous botany is small, but the diversity of
| different trapping mechanisms raises an evolutionary question.
|
| Isn't the obvious conclusion that: 1. There are many peaks in the
| fitness hypersurface for plants that correspond to meat eating 2.
| The peaks have smooth gradients at the outskirts 3. All peaks are
| minor local maxima
|
| 1 is because low nitrogen alone is not enough to make carnivory a
| net positive contributor to fitness. You need additional factors
| to make the gradient positive to begin with. That means the peaks
| (niches) are random and narrow.
|
| 3 is because carnivory implies an arms race against prey
| defenses, competing scavengers, and competing predators.
| Specialist animals are at a large advantage against plants,
| especially if meat is still a side dish to sunlight.
|
| To me the interesting question is 2 - most plants don't digest
| animals at all, so how does this begin to evolve?
| phkahler wrote:
| How about: larger animals can learn from seeing others eaten, so
| they won't fall for the trap.
| moate wrote:
| I mean, that's a weak evolutionary argument against all forms
| of predation/prey. It assumes a level of cultural/shared
| knowledge that doesn't typically exist. Also, size =\=
| intelligence/problem solving. Chimps and humans are both
| smarter than gorillas.
|
| Yes, troop 1 of monkeys have learned about the monkey-eating
| plants that have evolved overnight, but troops 2-10 haven't.
| Eventually troop 1 leaves the deadly forest, and troop 2 comes
| in. After a few seasons, they notice these fucking plants keep
| eating their babies (again, most predators go after babies for
| the reason you mentioned, they haven't learned how to avoid
| death yet) and then they move on. Repeat for several centuries.
| Behold nature in all its splendor.
|
| I like the article's ideas: If you can grow large enough to eat
| a person, you're getting enough nutrition that you don't need
| to eat a person.
| MisterBastahrd wrote:
| Because a fly can spit on your food, but a mouse can eat a hole
| in your baseboards.
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